Effects of carrying backpacks on the foot

NewsBot · Sep 12, 2013

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Effects of carrying a backpack in a symmetrical manner on the shape of the feet.
Drzał-Grabiec J, Snela S, Rachwał M, Rykała J, Podgórska J.
Ergonomics. 2013 Sep 10.

The aim of this study was to assess changes in the shape of the feet while carrying a backpack constituting 10% of a child's weight. It was an observational, cross-sectional study involving 118 primary school children aged 11-13 years. Selected parameters of foot shape were assessed in both a normal position and with a backpack using podoscopy and a CQ-ST examination device. The study revealed significant differences in the length and width of the right and left feet between assessments. Moreover, the longitudinal arch of the foot was significantly lowered and deformity of the great toe was reported. Carrying a backpack constituting 10% of a child's weight results in lowering of the longitudinal and traverse arches of the feet and advanced toe deformities. Practitioner Summary: We performed an observational, cross-sectional study examining the effect of carrying a backpack constituting 10% of a child's weight on parameters of foot shape and observed significant lowering of the longitudinal and traverse arches of the feet and advanced toe deformities.
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Admin2 · Sep 13, 2013

Related Threads:
Other threads tagged with military or obesity
Risk Factors for Musculoskeletal Injuries for Soldiers Deployed to Afghanistan
The effect ofload carriage during walking on lower limb
Obesity 'damages children's feet'
Obesity and Foot Posture

HansMassage · Sep 16, 2013

It would be interesting to compare a shoulder back pack with a hip bearing back pack to see if the forward leaning posture is part of the component of the foot adaptations.

NewsBot · Oct 30, 2013

Kinetic changes in gait during low magnitude military load carriage.
Majumdar D, Pal MS, Pramanik A, Majumdar D.
Ergonomics. 2013 Oct 29.

Indian infantry soldiers carry smaller magnitudes of loads for operational requirements. The ground reaction forces (GRFs) and impulse responses of 10 healthy male Indian infantry soldiers were collected while they walked carrying operational loads between 4.2 and 17.5 kg (6.5-27.2% of mean body weight (BW)) and a control condition of no external load (NL). The GRF and impulse components were normalised for BW, and data for each load condition were compared with NL in each side applying one-way analysis of variance followed by Dunnett's post hoc test. Right foot data were compared with corresponding left foot GRF data for all load conditions and NL. There were significant increases in vertical and anteroposterior GRFs with increase in load. Left and right feet GRF data in corresponding load conditions were significantly different in anteroposterior plane. No significant change was observed in the temporal components of support phase of gait. Changes in impulse parameter were observed in the anteroposterior and vertical planes while carrying load greater than 23 and 16.6% of BW for the right foot and left foot, respectively. Result indicates that smaller magnitudes of loads produced kinetic changes proportional to system weight, similar to heavier loads with the possibility of increased injury risk. Observed smaller asymmetric changes in gait may be considered as postural adjustment due to load. Unique physical characteristics of Indian soldiers and the probable design shortcomings of the existing backpack might have caused significant changes in GRF and peak impulse during smaller load carriage.

Practitioner Summary: This study evaluates stress on foot by recording GRF and impulse changes due to small increments of comparatively lighter military loads. Such data should be considered in evaluating the injury risk of feet during the process of optimisation of safer military load carriage and overall improvement in combat performances.
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NewsBot · Jan 8, 2014

The effect of backpack load on muscle activities of the trunk and lower extremities and plantar foot pressure in flatfoot.
Son H.
J Phys Ther Sci. 2013 Nov;25(11):1383-6.

[Purpose] The purpose of this study was to investigate the changes in muscle activation of the trunk and lower extremities and plantar foot pressure due to backpack loads of 0, 10, 15, and 20% of body weight during level walking in individuals with flatfoot.

[Methods] Fourteen young flatfoot subjects and 12 normal foot subjects participated in this study. In each session, the subjects were assigned to carry a backpack load, and there were four level walking modes: (1) unloaded walking (0%), (2) 10% body weight (BW) load, (3) 15% BW load, and (4) 20% BW load. Trunk and lower extremity muscle activities were recorded by surface EMG, and contact area and plantar foot pressure were determined using a RS scan system.

[Results] The erector spinae, vastus medialis, tibialis anterior and gastrocnemius muscle activities, but not the rectus femoris and rectus abdominis muscle activities of flatfoot subjects significantly and progressively increased as load increased in flatfoot subjects. Contact area and pressure of the lateral and medial heel zones were significantly increased too.

[Conclusion] Based on this data, the weight of a backpack could influence muscle activation and plantar foot pressure in flatfoot.
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HansMassage · Jan 9, 2014

I interpret that to be that individuals with flat feet tend to compensate by flexing more at the hips to carry the weight further forward on the foot.

NewsBot · Nov 1, 2014

Study on plantaer pressure distribution of people walking with different backpack load
Chen H, Liu H, Zhang J, Qiao G.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2013 Jun;30(3):525-9.

The purpose of this study was to investigate the effect of different backpack load on the plantar pressure of people during walking. By using three-dimensional force platform system, we collected the ground reaction force data from 20 college students, who were carrying different loads on their backs, and then we transformed the data into a characteristic two-peak curve. Seven characteristic parameters on the curve were selected and analyzed by using statistical methods. The results indicated that the peak ground reaction forces increased as the loads increased. Furthermore, in consideration of different genders, the amount increased was different. For the male subjects, when backpack load reached 17% body weight, changes in ground reaction force began to take place until the backloads reached 20% body weight changes in ground reaction force induced a significant difference. Por the female subjects, changes in ground reaction force began to take place with loads up to 14% body weight and while it reached 15% body weight it induced a significant difference.
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NewsBot · Nov 8, 2014

EFFECT OF MODE OF LOAD CARRIAGE ON POSTURAL SWAY
Melissa A. Mache, Alexa J. Janicki, Natasha P. Holland
International Conference of Biomechanics in Sports (2014)

People commonly carry external loads for sport and recreational purposes; recently the safety of such practice has come into question. The purpose of this study was to evaluate balance under different load carriage conditions. Fifteen college-age individuals completed three blocks of quiet standing trials: unloaded, wearing a backpack, and wearing a shoulder bag. A-P sway amplitude was greater under the backpack condition than the unloaded condition (P = 0.013); however, A-P sway amplitude did not differ between the backpack and shoulder bag condition, nor did it differ between the unloaded and shoulder bag condition. M-L sway amplitude, sway area, peak sway velocity, and stance width were not dependent on load condition. This evidence suggests a backpack and shoulder bag are equally safe means of load carriage in college-age individuals.
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NewsBot · Nov 19, 2014

Lower extremity mechanics during marching at three different cadences for 60 minutes.
Seay JF, Frykman PN, Sauer SG, Gutekunst DJ.
J Appl Biomech. 2014 Feb;30(1):21-30.

During group marches, soldiers must walk in step with one another at the same imposed cadence. The literature suggests that shorter trainees may be more susceptible to injury due to overstriding that can occur when taller recruits dictate marching cadence. This study assessed the effects of fixed cadence simulated marching at cadences above and below preferred step rate (PSR) on lower extremity joint mechanics in individuals who were unaccustomed to marching. During three separate visits, 13 volunteers walked with a 20 kg load on a force-sensing treadmill at self-selected PSR, PSR+15% (shorter strides), and PSR-15% (longer strides) at 1.3 m/s for 60 min. Two-way RM ANOVAs (cadence by time) were performed during the stance phase. Ranges of motion and anteroposterior ground reaction force increased significantly as cadence decreased (P < .03). Knee extension moment increased slightly when step rate decreased from PSR+15% (shortest strides, 0.85 ± 0.2 N m/kg) to PSR (0.87 ± 0.3 N m/kg, 3% increase); however, this increase was substantially greater (20% increase) when cadence was decreased from PSR to PSR-15% (longest strides, 1.09 ± 0.3 N m/kg). Our results indicate that overstriding during fixed-cadence marching is a factor that can substantially increase mechanical stress on lower extremity joints.
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NewsBot · Jan 30, 2015

Load Carriage-Related Injury Mechanisms, Risk Factors, and Prevention
Joseph J. Knapik, Katy Reynolds
Studies in Mechanobiology, Tissue Engineering and Biomaterials 2015

Since the beginning of recorded history, soldiers have been required to carry arms and equipment on their bodies. Recently, the weight of these loads has substantially increased due to improvements in weapons and personal protection. As soldier loads increase there are increases in energy cost, altered gait mechanics, increased stress on the musculoskeletal system, and more rapid fatigue, factors that may increase the risk of injury. Passive surveillance of injuries experienced by soldiers on load carriage missions and surveys of hikers and backpackers indicate that foot blisters, stress fractures, compression-related paresthesias (brachial plexus palsy, meralgia paresthetica, digitalgia paresthetica), metatarsalgia, knee problems, and back problems are among the most common load carriage-related maladies. This article discussed these injuries providing incidences, rates, symptoms, mechanisms, and risk factors, and provides evidence-based preventative measures to reduce injury risk. In general, lighter loads, improving load distribution, using appropriate physical training, selecting proper equipment, and using specific techniques directed at injury prevention will facilitate load carriage. An understanding of injury mechanisms and implementation of appropriate prevention strategies will provide service members a higher probability of mission success.
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NewsBot · Feb 18, 2015

Effect of firefighters' personal protective equipment on gait.
Park H, Kim S, Morris K, Moukperian M, Moon Y, Stull J
Appl Ergon. 2015 May;48:42-8.

The biomechanical experiment with eight male and four female firefighters demonstrates that the effect of adding essential equipment: turnout ensemble, self-contained breathing apparatus, and boots (leather and rubber boots), significantly restricts foot pronation. This finding is supported by a decrease in anterior-posterior and medial-lateral excursion of center of plantar pressure (COP) trajectory during walking. The accumulation of this equipment decreases COP velocity and increases foot-ground contact time and stride time, indicating increased gait instability. An increase in the flexing resistance of the boots is the major contributor to restricted foot pronation and gait instability as evidenced by the greater decrease in excursion of COP in leather boots (greater flexing resistance) than in rubber boots (lower resistance). The leather boots also shows the greatest increase in foot contact time and stride time. These negative impacts can increase musculoskeletal injuries in unfavorable fire ground environments
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NewsBot · Mar 5, 2015

Human Footprint Variation while Performing Load Bearing Tasks.
Wall-Scheffler CM, Wagnild J, Wagler E.
PLoS One. 2015 Mar 4;10(3):e0118619. doi: 10.1371/journal.pone.0118619.

Human footprint fossils have provided essential evidence about the evolution of human bipedalism as well as the social dynamics of the footprint makers, including estimates of speed, sex and group composition. Generally such estimates are made by comparing footprint evidence with modern controls; however, previous studies have not accounted for the variation in footprint dimensions coming from load bearing activities. It is likely that a portion of the hominins who created these fossil footprints were carrying a significant load, such as offspring or foraging loads, which caused variation in the footprint which could extend to variation in any estimations concerning the footprint's maker. To identify significant variation in footprints due to load-bearing tasks, we had participants (N = 30, 15 males and 15 females) walk at a series of speeds carrying a 20kg pack on their back, side and front. Paint was applied to the bare feet of each participant to create footprints that were compared in terms of foot length, foot width and foot area. Female foot length and width increased during multiple loaded conditions. An appreciation of footprint variability associated with carrying loads adds an additional layer to our understanding of the behavior and morphology of extinct hominin populations.
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NewsBot · May 2, 2015

Effect of backpack position on foot weight distribution of school-aged children.
Kim K, Kim CJ, Oh DW
J Phys Ther Sci. 2015 Mar;27(3):747-9

[Purpose] In the present study, we aimed to determine the effects of backpack position on foot weight distribution of standing school-aged children.
[Subjects] Thirty school-aged children volunteered to participate in this study. [Methods] The subjects randomly performed four types of carrying a backpack: no backpack (condition-1), carrying a backpack at C7 (condition-2), carrying a backpack at 10 cm below C7 (condition-3), and carrying a backpack at 20 cm below C7 (condition-4).
[Results] Statistically significant differences were noted in the anterior and posterior pressure values, and in the anterior-to-posterior ratio, among the four conditions (p < 0.05). Post-hoc analysis indicated that the pressure value of condition-4 was significantly lower in the anterior foot region and higher in the posterior foot region than in condition-2 and condition-3. In addition, the anterior-to-posterior ratio was lower in condition-4 than in condition-2 and condition-3.
[Conclusion] These findings suggest that carrying a backpack in a higher position, with fastening of the shoulder strap, may be more favorable for normalizing the foot weight distribution.
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NewsBot · May 6, 2015

Effects of Load Carriage and Footwear on Spatiotemporal Parameters, Kinematics, and Metabolic Cost of Walking
Kevin D. Dames, Jeremy D. Smith
Gait and Posture; Article in Press

Highlights
•We compare the effects of loading and footwear on walking gait.
•Loading increases cost of walking.
•Loading does not influence spatiotemporal parameters.
•Spatiotemporal changes while barefoot are not influenced by loading.
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Gait patterns are commonly altered when walking or running barefoot compared to shod conditions. Although controversy exists as to whether barefoot conditions result in lower metabolic costs, it is clear that adding load to the body results in increased metabolic costs. The effects of footwear and backpack loading have been investigated separately, but it is unclear whether manipulating both simultaneously would cause similar outcomes. Twelve healthy individuals (7 female, 5 male) with no obvious gait abnormalities participated in this study (age = 24 ± 2 years, height = 1.73 ± 0.13 m, and mass = 71.1 ± 16.9 kg). Steady state metabolic data and 3D motion capture were collected during treadmill walking at 1.5 m·s−1 in four conditions: Barefoot Unloaded, Shod Unloaded, Barefoot Loaded, and Shod Loaded. Barefoot walking elicited shorter stride lengths, stance and double support times, as well as a slight (≈1%), but not significant, decrease in metabolic cost. Loading increased metabolic costs of walking but did not elicit spatiotemporal changes in either footwear condition. Lower limb kinematic differences were noted in response to both loading and footwear. Changes in spatiotemporal parameters observed when walking barefoot were not exacerbated by the addition of a backpack load. This suggests that the increased metabolic demand associated with the load is met with a similar spatiotemporal pattern whether a person wears a supportive shoe or not. Thus, the discomfort associated with foot strike while barefoot that promotes spatiotemporal changes seems to be independent of load.
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NewsBot · Aug 1, 2015

School-Based Screening of Plantar Pressures During Level Walking with a Backpack among Overweight and Obese Schoolchildren.
Pau M, Leban B, Corona F, Gioi S, Nussbaum MA.
Ergonomics. 2015 Jul 30:1-26

Among children, postural modifications due to backpack carriage have direct consequences on how forces are exchanged between body and ground and thus on plantar pressure distribution. However, it is unknown whether such alterations are influenced by the foot structure and functionality typical of obesity. In this study, we tested 65 overweight/obese primary schoolchildren using a pressure platform while walking with and without the backpack. Contact areas, arch index, peak and mean plantar pressures in the forefoot, midfoot and rearfoot were compared with those from an additional 65 age- and gender-matched group of normal-weight children. Backpack carriage modified pressure distribution similarly in both groups, with the exception of mean midfoot pressure, which increased significantly among normal-weight children but not in the overweight/obese group. Notably, the pressures values associated with mass excess and backpack carriage still raise some concerns regarding potential long-term adverse consequences on foot structure and functionality of overweight/obese children. Practitioner summary Backpack carriage by overweight/obese schoolchildren altered plantar pressures similar to what was observed in their normal-weight peers. Yet, high pressures were found among the overweight/obese children. This raises concerns regarding potential long-term adverse consequences on foot structure and functionality, and supports establishing more specific limits for the carried load
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NewsBot · Aug 28, 2015

The effects of backpack loads and spinal stabilization exercises on the dynamic foot pressure of elementary school children with idiopathic scoliosis.
Lee S, Shim J.
J Phys Ther Sci. 2015 Jul;27(7):2257-2260

[Purpose] The purpose of this study was to measure and observe the changes in dynamic plantar pressures when school children carried specific bag loads, and to determine whether improved physical balance after an eight-week spinal stabilization exercise program can influences plantar pressures.
[Subjects] The subjects were 10 school students with Cobb angles of 10? or greater.
[Methods] Gait View Pro 1.0 (Alfoots, Korea) was were based on to measure the pressure of the participants' feet. Spinal stabilization exercises used TOGU Multi-roll Functional (TOGU, Germany) training. Dynamic plantar pressures were measured with bag loads of 0% no bag and 15% of subjects' body weight. The independent t test was performed to analyze changes in plantar pressures.
[Results] The plantar pressure measurements of bag load of 0% of subjects' body weight before and after the spinal stabilization exercise program were not significantly different, but those of two foot areas with a 15% load were statistically significant (mt5, 67.32?24.25 and 51.77?25.52 kPa; lat heel, 126.00?20.46 and 102.08?23.87 kPa).
[Conclusion] After performance of the spinal stabilization exercises subjects' overall plantar pressures were reduced, which may suggest that physical balance improved.
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NewsBot · Nov 4, 2015

Kinematic and ground reaction force accommodation during weighted walking
C. Roger James et al
Human Movement Science; Volume 44, December 2015, Pages 327–337

Highlights
•Subjects walked while carrying weights in two hands in front of the body.
•COM motion and peak GRF increased, stride length decreased, posture became more upright.
•Changes in peak GRF were predicted by changes at the hip, thigh and foot.
•Subject classification revealed different accommodation strategies, which could affect loading and stability.
•Greater and lesser increases in peak GRF were related to general and foot/trunk-specific kinematic changes, respectively.
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Weighted walking is a functional activity common in daily life and can influence risks for musculoskeletal loading, injury and falling. Much information exists about weighted walking during military, occupational and recreational tasks, but less is known about strategies used to accommodate to weight carriage typical in daily life. The purposes of the study were to examine the effects of weight carriage on kinematics and peak ground reaction force (GRF) during walking, and explore relationships between these variables. Twenty subjects walked on a treadmill while carrying 0, 44.5 and 89 N weights in front of the body. Peak GRF, sagittal plane joint/segment angular kinematics, stride length and center of mass (COM) vertical displacement were measured. Changes in peak GRF and displacement variables between weight conditions represented accommodation. Effects of weight carriage were tested using analysis of variance. Relationships between peak GRF and kinematic accommodation variables were examined using correlation and regression. Subjects were classified into sub-groups based on peak GRF responses and the correlation analysis was repeated. Weight carriage increased peak GRF by an amount greater than the weight carried, decreased stride length, increased vertical COM displacement, and resulted in a more extended and upright posture, with less hip and trunk displacement during weight acceptance. A GRF increase was associated with decreases in hip extension (|r| = .53, p = .020) and thigh anterior rotation (|r| = .57, p = .009) displacements, and an increase in foot anterior rotation displacement (|r| = .58, p = .008). Sub-group analysis revealed that greater GRF increases were associated with changes at multiple sites, while lesser GRF increases were associated with changes in foot and trunk displacement. Weight carriage affected walking kinematics and revealed different accommodation strategies that could have implications for loading and stability.
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NewsBot · Jan 23, 2016

Load Distribution and Postural Changes in Young Adults When Wearing a Traditional Backpack Versus the BackTpack
Kimberly D. Dahl, He Wang, Jennifer K. Popp, D. Clark Dickin
Gait and Posture; Article in Press

Highlights
•Examines backpack load distribution effects on posture and gait.
•Traditional backpack results in more forward trunk flexion and neck hyperextension.
•Nontraditional backpack more similar to unloaded posture than traditional backpack.
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Backpacks lead to poor posture due to the posterior placement of the load, which overtime may contribute to low back pain and musculoskeletal complications. This study examined postural and load distribution differences between a traditional backpack (BP) and a nontraditional backpack (BTP) in a young adult population. Using a 3D motion analysis system, 24 healthy young adults (22.5 ? 2.5 years, 12 male) completed both static stance and walking trials on a treadmill with no load and with 15% and 25% of their body weight using the two different backpacks. There was a significant difference in trunk angle, head angle, and lower extremity joint mechanics between the backpack and load conditions during walking (p<.05). Notably, relative to the No Load condition, trunk angle decreased approximately 14? while head angle increased approximately 13? for the BP 25% state on average. In contrast, average trunk and head angle differences for the BTP 25% state were approximately 7.5? and 7?, respectively. There was also a significant difference in head angle from pre- to post-walk (p<.05) across backpacks, loads, and time. Taken together, the results indicate that the BTP more closely resembled the participants’ natural stance and gait patterns as determined by the No Load condition. The more upright posture supported by the BTP may help reduce characteristics of poor posture and, ideally, help to reduce low back pain while carrying loads.
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David Smith · Jan 25, 2016

"Effects of wearing backpacks on the foot" surely you should wear your backpack on your back, not on your foot?

NewsBot · Apr 19, 2016

Use of a backpack alters gait initiation of high school students.
Vieira MF et al
J Electromyogr Kinesiol. 2016 Apr 8;28:82-89

We assessed how backpack carriage influences the gait initiation (GI) process in high school students, who extensively use backpacks. GI involves different dynamics from gait itself, while the excessive use of backpacks can result in adverse effects. 117 high school students were evaluated in three experimental conditions: no backpack (NB), bilateral backpack (BB), and unilateral backpack (UB). Two force plates were used to acquire ground reaction forces (GRFs) and moments for each foot separately. Center of pressure (COP) scalar variables were extracted, and statistical parametric mapping analysis was performed over the entire COP/GRFs time series. GI anticipatory postural adjustments (APAs) were reduced and were faster in backpack conditions; medial-lateral COP excursion was smaller in this phase. The uneven distribution of the extra load in the UB condition led to a larger medial-lateral COP shift in the support-foot unloading phase, with a corresponding vertical GRF change that suggests a more pronounced unloading swing foot/loading support foot mechanism. The anterior-posterior GRFs were altered, but the COP was not. A possible explanation for these results may be the forward trunk lean and the center of mass proximity of the base of support boundary, which induced smaller and faster APA, increased swing foot/support foot weight transfer, and increased load transfer to the first step.
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NewsBot · Apr 22, 2016

Joint power and kinematics coordination in load carriage running: Implications for performance and injury
Bernard X.W. Liew, Susan Morris, Kevin Netto
Gait and Posture; Article in Press

Highlights
?Load carriage altered inter-joint power coordination during running.
?Load carriage altered three-dimensional kinematics in running.
?The effect of load magnitude on running mechanics depended on velocity.
?Mechanical responses to load carriage may be used to guide future interventions.
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Investigating the impact of incremental load magnitude on running joint power and kinematics is important for understanding the energy cost burden and potential injury-causative mechanisms associated with load carriage. It was hypothesized that incremental load magnitude would result in phase-specific, joint power and kinematic changes within the stance phase of running, and that these relationships would vary at different running velocities. Thirty-one participants performed running while carrying three load magnitudes (0%, 10%, 20% body weight), at three velocities (3, 4, 5 m/s). Lower limb trajectories and ground reaction forces were captured, and global optimization was used to derive the variables. The relationships between load magnitude and joint power and angle vectors, at each running velocity, were analysed using Statistical Parametric Mapping Canonical Correlation Analysis. Incremental load magnitude was positively correlated to joint power in the second half of stance. Increasing load magnitude was also positively correlated with alterations in three dimensional ankle angles during mid-stance (4.0 and 5.0 m/s), knee angles at mid-stance (at 5.0 m/s), and hip angles during toe-off (at all velocities). Post-hoc analyses indicated that at faster running velocities (4.0 and 5.0 m/s), increasing load magnitude appeared to alter power contribution in a distal-to-proximal (ankle → hip) joint sequence from mid-stance to toe-off. In addition, kinematic changes due to increasing load influenced both sagittal and non-sagittal plane lower limb joint angles. This study provides a list of plausible factors that may influence running energy cost and injury risk during load carriage running.
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NewsBot · Apr 26, 2016

Moving in extreme environments: extreme loading; carriage versus distance
Samuel J. E. Lucas, Jorn W. Helge, Uwe H. W. Schutz, Ralph F. Goldman and James D. Cotter
Extreme Physiology & Medicine 20165:6 (full text)

This review addresses human capacity for movement in the context of extreme loading and with it the combined effects of metabolic, biomechanical and gravitational stress on the human body. This topic encompasses extreme duration, as occurs in ultra-endurance competitions (e.g. adventure racing and transcontinental races) and expeditions (e.g. polar crossings), to the more gravitationally limited load carriage (e.g. in the military context). Juxtaposed to these circumstances is the extreme metabolic and mechanical unloading associated with space travel, prolonged bedrest and sedentary lifestyle, which may be at least as problematic, and are therefore included as a reference, e.g. when considering exposure, dangers and (mal)adaptations. As per the other reviews in this series, we describe the nature of the stress and the associated consequences; illustrate relevant regulations, including why and how they are set; present the pros and cons for self versus prescribed acute and chronic exposure; describe humans’ (mal)adaptations; and finally suggest future directions for practice and research. In summary, we describe adaptation patterns that are often U or J shaped and that over time minimal or no load carriage decreases the global load carrying capacity and eventually leads to severe adverse effects and manifest disease under minimal absolute but high relative loads. We advocate that further understanding of load carrying capacity and the inherent mechanisms leading to adverse effects may advantageously be studied in this perspective. With improved access to insightful and portable technologies, there are some exciting possibilities to explore these questions in this contex
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NewsBot · Aug 13, 2016

The effects of load carriage on joint work at different running velocities
Bernard X.W. Liew, Susan Morris, Kevin Netto
Jnl Biomech; Article in Press

Running with load carriage has become increasingly prevalent in sport, as well as many field-based occupations. However, the 'sources' of mechanical work during load carriage running are not yet completely understood. The purpose of this study was to determine the influence of load magnitudes on the mechanical joint work during running, across different velocities. Thirty-one participants performed overground running at three load magnitudes (0%, 10%, 20% body weight), and at three velocities (3, 4, 5 m/s). Three dimensional motion capture was performed, with synchronised force plate data captured. Inverse dynamics was used to quantify joint work in the stance phase of running. Joint work was normalized to a unit proportion of body weight and leg length (one dimensionless work unit=532.45 J). Load significantly increased total joint work and total positive work and this effect was greater at faster velocities. Load carriage increased ankle positive work (β coefficient=rate of 6.95?10−4 unit work per 1% BW carried), and knee positive (β=1.12?10−3 unit) and negative work (β=−2.47?10−4 unit), and hip negative work (β=−7.79?10−4 unit). Load carriage reduced hip positive work and this effect was smaller at faster velocities. Inter-joint redistribution did not contribute significantly to increased total work within the spectrum of load and velocity investigated. Hence, the ankle joint contributed to the greatest extent in work production, whilst that of the knee contributed to the greatest extent to work absorption when running with load.
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NewsBot · Oct 23, 2016

Effect of backpack strap patterns on gait parameters in young adults at self-selected normal and fast walking speeds
Ukachukwu Okoroafor Abaraogu, et al
PM & R; Article in Press

Background
The effects of backpack load on young adults' gait parameters have received little attention. This author group previously reported that with a backpack load within 15% body weight, young adults maintain their gait parameters at the expense of increased exertion during a 6-minute walk at self-selected normal walking speed. However, the effect of backpack strap pattern on gait parameters during faster walking or longer stride length has not been evaluated.

Objective
To determine the effect of different backpack strap patterns on gait parameters during 12 minute duration walk test in young adults at self-selected normal and fast walking speeds.

Design
A cross-over, self-controlled experimental study with repeated measure.

Setting
Department of Medical Rehabilitation University of Nigeria.

Participants
A convenience sample of 24 healthy young adults (21.29±1.20 years)who voluntarily signed an informed consent, were able to wear a backpack on one and on both shoulders, were able to walk independently and passed the physical activity readiness screening participated in this study.

Methods
Using a validated method of an observational gait analysis, each participant carried out a 12-minute walk test at self-determined normal and fast walking speeds respectively. The effect of the following test conditions on the selected gait parameters was evaluated: normal and fast walking without load, and normal and fast walking with 10% and 20% BW backpack carried each on one and both shoulders.

Main outcome measurement
Stride length, stride time, velocity, cadence and base of support were assessed by the equation definitions method of the velocity field diagram.

Results
At self-selected fast walking speed with 10%BW backpack load, stride time (p=.004) and cadence (p=.006) were significantly decreased when participants wore double strap backpack. At self-selected normal walking speed with 20%BW backpack load, cadence was significantly decreased with double strap backpack carriage (p=.008).Cadence (p<.001), velocity (p<.001) and stride time (p<.001)were also significantly decreased at both conditions of single and double strap backpack carriage of 20% BW respectively at fast walking speed.

Conclusion
Backpack strap patterns do not affect the gait parameters of young adults in a 12 minute bout of normal walking speed provided the load is less than 20%BW. However, a load up to 10%BW carried on a double strap causes a decrease in stride time and cadence when they walk fast.
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NewsBot · Nov 5, 2016

The effects of body-borne loads and cadence manipulation on patellofemoral and tibiofemoral joint kinetics during running
Richard W. Willy et al
Journal of Biomechanics; in press

Understanding how body-borne mass influences knee loads during running and how to modulate these knee loads may assist efforts to reduce the high rate of knee injuries in military populations. We tested a) the extent a 15-kg body-borne load affects peak and cumulative patellofemoral (PFJ) and tibiofemoral (TFJ) contact forces during running and b) if a 7.5% increase in running cadence modulates these contact forces. Compared with unloaded running, the body-borne load increased peak PFJ contact force (+0.2 body weights (BW); p=0.001) and PFJ impulse (+32 body weights per km; p<0.001). Additionally, greater total TFJ peak contact force (+0.5 body weights; p<0.001) and greater peak medial TFJ contact force (+0.4 body weights; p=0.002) resulted with the added load. Similarly, 85 additional body weights of total TFJ impulse per km (p<0.001) and 65 additional body weights of medial TFJ impulse per km (p<0.001) were noted with the added load. The higher cadence condition reduced peak PFJ force (-0.5 body weights, p<0.001) and PFJ impulse per km (-15 body weights per km, p<0.016). Reduced peak total and peak medial TFJ contact force (-0.8 body weights, p<0.001; -0.5 body weights, p<0.001, respectively) were also found with higher cadence, while reduced total TFJ and medial TFJ impulse per km (-18.5 body weights per km, p<0.001; -12.2 body weights per km, p<0.001, respectively) were observed. Thus, running with increased cadence eliminated increases in knee loads per step but only partially reduced the greater cumulative knee loads that resulted with an added 15-kg body-borne load.
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NewsBot · Nov 26, 2016

Gender differences in load carriage injuries of Australian army soldiers.
Orr RM, Pope R
BMC Musculoskelet Disord. 2016 Nov 25;17(1):488.

BACKGROUND:
With the removal of gender restrictions and the changing nature of warfare potentially increasing female soldier exposure to heavy military load carriage, the aim of this research was to determine relative risks and patterns of load carriage related injuries in female compared to male soldiers.
METHODS:
The Australian Defence Force Occupational Health, Safety and Compensation Analysis and Reporting workplace injury database was searched to identify all reported load carriage injuries. Using key search terms, the narrative description fields were used as the search medium to identify records of interest. Population estimates of the female: male incident rate ratio (IRR) were calculated with ninety-five percent confidence interval (95% CI) around the population estimate of each IRR determined.
RESULTS:
Female soldiers sustained 10% (n = 40) of the 401 reported injuries, with a female to male IRR of 1.02 (95% CI 0.74 to 1.41). The most common site of injury for both genders was the back (F: n = 11, 27%; M: n = 80, 22%), followed by the foot in female soldiers (n = 8, 20%) and the ankle (n = 60, 17%) in male soldiers. Fifteen percent (n = 6) of injuries in female soldiers and 6% (n = 23) of injuries in males were classified as Serious Personal Injuries (SPI) with the lower back the leading site for both genders (F: n = 3, 43%: M: n = 8, 29%). The injury risk ratio of SPI for female compared to male soldiers was 2.40 (95% CI 0.98 to 5.88).
CONCLUSIONS:
While both genders similarly have the lower back as the leading site of injury while carrying load, female soldiers have more injuries to the foot as the second leading site of injury, as opposed to ankle injuries in males. The typically smaller statures of female soldiers may have predisposed them to their observed higher risk of suffering SPI while carrying loads.
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NewsBot · Nov 29, 2016

CHILDREN REQUIRE LESS GAIT KINEMATIC ADAPTATIONS TO PULL A TROLLEY THAN TO CARRY A BACKPACK
Eva Orantes-Gonzalez et al
Gait and Posture; Article in Press

Highlights
•The gait kinematics were compared carrying a backpack and pulling a trolley.
•Pulling a trolley did not alter the spatiotemporal variables from control gait.
•Carrying a backpack produced larger kinematics and gait changes.
•Trolley use produced a close kinematic pattern to control but different from backpack.
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To transport school materials, trolleys have been proposed for children as an alternative to carrying a backpack. However, there is limited evidence comparing the adaptations associated with carrying school trolley versus backpack. This study compared the effects of carrying a backpack and pulling a trolley on gait kinematics in children. Fifty-three students were evaluated. Children walked at self-selected speeds across a walkway with no bag (control), carrying a backpack with the 15% of child́s body weight (%BW) and pulling a trolley with the same load. Spatiotemporal gait parameters and 3D kinematics of lower extremities and thorax were computed. No significant differences were obtained in spatiotemporal parameters between pulling a trolley and control. Carrying a backpack resulted in larger kinematics gait alterations than pulling the trolley compared to control. In conclusion, pulling a school trolley (15%BW) was more similar to not carrying a bag than carrying a backpack of the same load during level walking.
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NewsBot · Mar 9, 2017

Carrying asymmetric loads during different walking conditions
Wang, Junsig.
Iowa State University, ProQuest Dissertations Publishing, 2016

The purpose of this dissertation was to investigate how asymmetric load carriage affects
joint kinetics and postural control during walking and stair negotiation.
In the first two studies, frontal plane joint moments were analyzed when carrying
unilateral versus bilateral loads during stair negotiation. Peak L5/S1 contralateral bending
moments were significantly higher when carrying a 20% body weight (BW) unilateral load for
both stair ascent and descent. In addition, peak external knee varus and hip abduction moments
were significantly higher in unloaded limb stance as compared to loaded limb stance. Based on
our findings, we suggest that the low back and lower extremity play different roles in adjusting
to asymmetric loads and recommend splitting loads bilaterally in order to decrease the frontal
plane joint moments.
In the last dissertation study, we assessed postural control when carrying unilateral versus
bilateral loads during walking on even and uneven surfaces. Carrying 20% BW bilateral or
unilateral loads resulted in a significantly higher double stance ratio than unloaded walking.
Carrying a 20% BW unilateral load or walking on an uneven surface resulted in a significantly
increased coefficient of variation (CV) of double stance ratio. Unloaded limb stance had a
significantly higher double stance ratio and mean medial-lateral (ML) center of pressure (COP)
velocity, although the loaded limb had a significantly higher CV of ML COP velocity. We
suggest that load carriage and unloaded limb stance require more conservative postural control,
while asymmetric loads and uneven surfaces require more step-by-step postural adjustments.
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NewsBot · Mar 28, 2017

A cross-sectional study of the effects of load carriage on running characteristics and tibial mechanical stress: implications for stress-fracture injuries in women
Chun Xu, Amy Silder, Ju Zhang, Jaques ReifmanEmail author and Ginu Unnikrishnan
BMC Musculoskeletal Disorders 23 March 2017

Background
Load carriage is associated with musculoskeletal injuries, such as stress fractures, during military basic combat training. By investigating the influence of load carriage during exercises on the kinematics and kinetics of the body and on the biomechanical responses of bones, such as the tibia, we can quantify the role of load carriage on bone health.

Methods
We conducted a cross-sectional study using an integrated musculoskeletal-finite-element model to analyze how the amount of load carriage in women affected the kinematics and kinetics of the body, as well as the tibial mechanical stress during running. We also compared the biomechanics of walking (studied previously) and running under various load-carriage conditions.

Results
We observed substantial changes in both hip kinematics and kinetics during running when subjects carried a load. Relative to those observed during running without load, the joint reaction forces at the hip increased by an average of 49.1% body weight when subjects carried a load that was 30% of their body weight (ankle, 4.8%; knee, 20.6%). These results indicate that the hip extensor muscles in women are the main power generators when running with load carriage. When comparing running with walking, finite element analysis revealed that the peak tibial stress during running (tension, 90.6 MPa; compression, 136.2 MPa) was more than three times as great as that during walking (tension, 24.1 MPa; compression, 40.3 MPa), whereas the cumulative stress within one stride did not differ substantially between running (15.2 MPa · s) and walking (13.6 MPa · s).

Conclusions
Our findings highlight the critical role of hip extensor muscles and their potential injury in women when running with load carriage. More importantly, our results underscore the need to incorporate the cumulative effect of mechanical stress when evaluating injury risk under various exercise conditions. The results from our study help to elucidate the mechanisms of stress fracture in women.
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NewsBot · Mar 28, 2017

Pattern of Alteration in Foot Mechanics When Carrying Loads Unilaterally in Hand
Harithasan D, Omar B, Paungmali A.
The Internet Journal of Allied Health Sciences and Practice. 2017 Mar 23;15(2), Article 7
PURPOSE: Carrying weight in one hand is a common functional activity. This study investigated the effects
of incremental loads carried in one hand unilaterally and its influence on the foot mechanics [plantar pressure,
maximum force and contact area].
METHOD: Twenty healthy individuals were tested, in standing and
walking, while carrying different weights (no load, 5 kg, 7.5 kg and 10 kg) using their right hand. ANCOVA
was conducted separately for the right and left leg to address the effect of incremental loads on the foot
mechanics within each leg with navicular drop index and Q angle as covariates. Paired t-test was conducted
to address the effect of different loads on the foot mechanics between the legs.
RESULTS: Results showed a
significant increase in plantar pressure
CONCLUSION: The fundamental changes in foot mechanics under
the influence of different loads may be used to interpret the changesseen in the foot mechanics among different
pathological condition.

NewsBot · May 23, 2017

Increase in Leg Stiffness Reduces Joint Work During Backpack Carriage Running at Slow Velocities
Bernard Liew, Kevin Netto, Susan Morris
Journal of Applied Biomechanics May 15, 2017

Optimal tuning of leg stiffness has been associated with better running economy. Running with load is energetically expensive, which could have a significant impact on athletic performance where backpack carriage is involved. The purpose of this study was to investigate the impact of load magnitude and velocity on leg stiffness. We also explored the relationship between leg stiffness and running joint work. Thirty-one healthy participants ran overground at three velocities (3.0, 4.0, 5.0 m.s-1), whilst carrying three load magnitude (0%, 10%, 20% weight). Leg stiffness was derived using the direct kinetic-kinematic method. Joint work data was previously reported in a separate study. Linear models were used to establish relationships between leg stiffness and load magnitude, velocity, and joint work. Our results found that leg stiffness did not increase with load magnitude. Increased leg stiffness was associated with reduced total joint work at 3.0 m.s-1, but not at faster velocities. The association between leg stiffness and joint work at slower velocities could be due to an optimal co-variation between skeletal and muscular components of leg stiffness, and limb attack angle. When running at a relatively comfortable velocity, greater leg stiffness may reflect a more energy efficient running pattern.
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NewsBot · Feb 21, 2018

Assessing gait changes in firefighters after firefighting activities and while carrying asymmetric loads
Kiwon Park et al
Applied Ergonomics Volume 70, July 2018, Pages 44–50

Highlights
•After firefighting activities, firefighters' gait performance declined.
•Carrying medial-lateral asymmetric load affected firefighters' gait parameters.
•Gait performance after live-fire or laboratory-simulated activities was similar.
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One of the most common causes of injuries among firefighters is slips, trips, and falls on the fireground. Acute fatigue from firefighting activities and/or carrying asymmetric loads might impact gait characteristics increasing slip, trip, and fall risk. The purpose of this study was to examine the effects of fatigue from simulated firefighting activities and carrying asymmetric loads (fire hose over one shoulder) on firefighters’ gait behavior. Both firefighting activities and asymmetric hoseload carriage led to shorter step lengths, stride lengths, single leg support time, and longer double leg support time, suggesting firefighters adopted cautious gait strategies. Simulated firefighting activities performed in either a live-fire training tower or laboratory-based environmental chamber using a firefighting activity simulator resulted in nearly identical effects on gait kinematics. This result suggests that gait assessment in a laboratory-based environmental chamber can be used as effective simulations in place of specialized burn facilities.
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NewsBot · Dec 16, 2018

INFLUENCE OF SCHOOLBAG CARRIAGE ON PATTERN
CHANGES IN PLANTAR PRESSURE DURING WALKING
AMONG FIRST-GRADE SCHOOLCHILDREN
Mario Kasović et al
Kinesiology 50(2018)2:xxx-xxx

The aim of this study was to determine the influence of schoolbag carriage on pattern changes in plantar
pressure during walking among schoolchildren of first grade. The sample consisted of 127 schoolchildren,
48.8% male (n = 62) and 51.2% female (n = 65), aged 6.7 (±0.5) years. The mean schoolbag weight was
4.2 kg (±0.7), which represented 16.9% (±3.9) of children’s body weight, thus exceeding the upper limit of
the recommended 15% of the body weight and generally affecting their posture. The study has shown the
statistically significant influence of the schoolbag on changes in plantar pressure pattern when walking
in relation to walking without the schoolbag. Using a t-test for large dependent samples and by setting
statistical significance at p≤.05, the significant increase was noticed in peak pressure for the forefoot (p=.000;
17.1%), midfoot (p=.000; 5.7%) and hindfoot (p=.004; 3.9%) as well as in average pressure for the midfoot
(p=.005; 6.2%). Also, due to the compensatory mechanisms activated while the bag was being carried, the
statistically significant increase in the contact surface at the forefoot (p=.000; 3.6%) and midfoot (p=.000,
8.8%) occurred. Changes in the distribution of pressure between different parts of the foot are a source of
potential foot problems which is why the results of this study have a high applicability in the prevention of
foot pathology in the futu
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NewsBot · Mar 7, 2019

The effects of backpack carriage on gait kinematics and kinetics of schoolchildren.
Ahmad HN, Barbosa TM
Sci Rep. 2019 Mar 4;9(1):3364

There has been a growing concern among clinical and educational practitioners, as well as, policy makers on the use of backpacks by schoolchildren. On a daily basis, pupils spend a significant amount of time carrying stuffed and heavy backpacks. The aim of this study was to investigate the effects of backpack carriage with different loads on spatiotemporal parameters of gait, plantar pressure and force distribution under different foot regions in schoolchildren. We have assessed fifty-seven primary school students (7-9 years-old) performing four walks of 10 m (carrying 0%, 10%, 15% of body mass in the backpack and the load they brought to school). A floor-based photocell system was used to collect the gait kinematics and insoles capacitive pressure sensors the kinetics. Children walked slower and at lower cadence with the load brought to school than in the other three conditions. There was no significant main effect on stride length. Backpack carriage with different loads did have a significant effect on plantar pressure and force distribution. We noted that heavier the load, higher the pressure and force under different foot regions. Our findings highlight that gait biomechanics of children (such as stride kinematics and pressure under the feet) is affected by carrying loads in the backpacks.
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NewsBot · Sep 15, 2019

Altered forefoot function following a military training activity
H.Rice et al
Gait & Posture; 10 September 2019

Highlights
•Completion of a military load carriage training activity alters plantar loading.
•Decreased forefoot loading and increased rearfoot loading after load carriage.
•Increased peak dorsiflexion and range of motion after load carriage.
•Later peak metatarsal pressure after load carriage – may relate to stress fracture.
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Background
Injury rates are high in populations that regularly undertake weight-bearing physical activity, particularly military populations. Military training activities, that often include load carriage, have been associated with lower limb injury occurrence, specifically stress fractures.

Research question
Recent work identified plantar loading variables as risk factors for lower limb stress fractures in Royal Marines recruits that were assessed during barefoot running. This study aimed to quantify how those plantar loading variables changed in Royal Marines recruits following a prolonged military load carriage activity, to further understand potential mechanisms for lower limb stress fractures.

Methods
Bilateral, synchronised plantar pressure and lower limb kinematic data were recorded during barefoot running at 3.6 m s-1 (±5%) pre- and post- a 12.8-km training activity (∼150 min). The training activity was completed with an average speed typical of walking (1.4 m.s-1), and 35.5 kg of additional load was carried throughout. Data were collected from 32 male Royal Marines recruits who completed the training activity in week-21 of the 32-week training programme. Plantar pressure variables and ankle dorsiflexion were compared between pre- and post-activity.

Results
Post-activity there was reduced loading under the forefoot and increased loading under the rearfoot and midfoot. There was no change in dorsiflexion touchdown angle, but an increase in peak dorsiflexion and range of motion post-activity.

Significance
The increased rearfoot loading, reduced forefoot loading and increased ankle dorsiflexion following a prolonged military load carriage activity suggest a reduced transfer of loading from the rearfoot to the forefoot during stance, which may have implications for the development of stress fractures, particularly of the metatarsals.
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NewsBot · Dec 12, 2019

Effects of heel height with backpack loading in young people.
Alsancak S et al
J Sports Med Phys Fitness. 2019 Dec 5

BACKGROUND:
There are many intrinsic and extrinsic factors that could affect posture. Two of them are backpack and heel height. The aim of this study is to investigate the immediate static effects on cervical and lumbosacral postural changes to determine the effects of heel and forefoot heights with backpack loading on both vertebral curves and posture.

METHODS:
Craniovertebral (CVA), pelvic tilt (APT), and ankle joint motion angles were measured from sagittal photographs of 20 university students in a static posture while carrying backpacks. The same measurements were taken and recorded conventional shoes with heel and forefoot heights. Postural analysis software (PAS/SAPO) was used to conduct angle assessments of the photos.

RESULTS:
Postural angles of the vertebral column on the cervical and lumbosacral regions are changed immediately up to the posterior thoracic load with backpacks in young people. CVA was an average of 52̊ only shoes and no load condition, while the angle was reduced to 49̊ with loading. In contrast, an increasing angle with additional heel height and zero heel height in conventional shoes were reported. CVA increased with heights to 53̊ for the heel and 55̊ at the forefoot. The average APT angle was 14̊ only shoes and no load condition, and this angle increased to 18.9̊ with the 20% BW load. Accordingly for the no load and load conditions, the significant increase in the APT angle was 21̊ with the 20% BW load with heel height and 23̊ for the 20% BW load along with forefoot height. The heights provided negative effects on the vertebral posture and ankle angle.

CONCLUSIONS:
The results of the study indicate that it may not be advisable for young people to wear shoes with high heels and negative heel height by taking into account the risk factors in the body and ankle postural compensation while carrying a backpack.
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NewsBot · Apr 1, 2020

Effects of heel height with backpack loading in young people
Serap ALSANCAK et al
The Journal of Sports Medicine and Physical Fitness 2020 March;60(3):388-94

BACKGROUND: There are many intrinsic and extrinsic factors that could affect posture. Two of them are backpack and heel height. The aim of this study is to investigate the immediate static effects on cervical and lumbosacral postural changes to determine the effects of heel and forefoot heights with backpack loading on both vertebral curves and posture.
METHODS: Craniovertebral (CVA), pelvic tilt (APT), and ankle joint motion angles were measured from sagittal photographs of 20 university students in a static posture while carrying backpacks. The same measurements were taken and recorded conventional shoes with heel and forefoot heights. Postural analysis software (PAS/SAPO) was used to conduct angle assessments of the photos.
RESULTS: Postural angles of the vertebral column on the cervical and lumbosacral regions are changed immediately up to the posterior thoracic load with backpacks in young people. CVA was an average of 52° only shoes and no load condition, while the angle was reduced to 49° with loading. In contrast, an increasing angle with additional heel height and zero heel height in conventional shoes were reported. CVA increased with heights to 53° for the heel and 55° at the forefoot. The average APT angle was 14° only shoes and no load condition, and this angle increased to 18.9° with the 20% BW load. Accordingly for the no load and load conditions, the significant increase in the APT angle was 21° with the 20% BW load with heel height and 23° for the 20% BW load along with forefoot height. The heights provided negative effects on the vertebral posture and ankle angle.
CONCLUSIONS: The results of the study indicate that it may not be advisable for young people to wear shoes with high heels and negative heel height by taking into account the risk factors in the body and ankle postural compensation while carrying a backpack.
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NewsBot · Aug 18, 2020

Center of Pressure, Vertical Ground Reaction Forces, and Neuromuscular Responses of Special-Forces Soldiers to 43-km Load Carriage in the Field
James Scales et al
J Appl Biomech. 2020 Aug 14;1-6

The primary purpose of this study was to examine lateral deviations in center of pressure as a result of an extreme-duration load carriage task, with particular focus on heel contact. A total of 20 (n = 17 males and n = 3 females) soldiers from a special operation forces unit (body mass 80.72 [21.49] kg, stature 178.25 [8.75] cm, age 26 [9] y) underwent gait plantar pressure assessment and vertical jump testing before and after a 43-km load carriage event (duration 817.02 [32.66] min) carrying a total external load of 29.80 (1.05) kg. Vertical jump height decreased by 18.62% (16.85%) from 0.30 (0.08) to 0.24 (0.07) m, P < .001. Loading peak and midstance force minimum were significantly increased after load carriage (2.59 [0.51] vs 2.81 [0.61] body weight, P = .035, Glass delta = 0.44 and 1.28 [0.40] vs 1.46 [0.41] body weight, P = .015, Glass delta = 0.45, respectively) and increases in lateral center of pressure displacement were observed as a result of the load carriage task 14.64 (3.62) to 16.97 (3.94) mm, P < .029. In conclusion, load carriage instigated a decrease in neuromuscular function alongside increases in ground reaction forces associated with injury risk and center of pressure changes associated with ankle sprain risk. Practitioners should consider that possible reductions in ankle stability remain once load carriage has been completed, suggesting soldiers are still at increased risk of injury even once the load has been removed.
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NewsBot · Aug 18, 2020

Effects of Carrying Police Equipment on Spatiotemporal and Kinetic Gait Parameters in First Year Police Officers
Mario Kasović et al
Int J Environ Res Public Health. 2020 Aug 9;17(16)

The main purpose of the study was to explore the effects of carrying police equipment on spatiotemporal and kinetic gait parameters. Two-hundred and seventy-five healthy men and women attending police academy (32% women) were randomly recruited. Gait analysis without and with a police equipment load (≈3.5 kg) was analyzed using the Zebris pressure platform. Differences and effect sizes were calculated using a Student t-test and Wilcoxon test for dependent samples and Cohen's D statistics. In both men and women, carrying police equipment significantly increased the foot rotation (effect size 0.13-0.25), step width (0.13-0.33), step time (0.25), stride time (0.13-0.25) and peak plantar pressure beneath the forefoot (0.16-0.30), midfoot (0.15-0.32) and hindfoot (0.13-0.25) region of the foot. Significant reductions in the step length (0.12-0.25), stride length (0.14-0.23), cadence (0.15-0.28) and walking speed (0.20-0.22) were observed in both sexes. Although significant, the effect sizes were mostly trivial in men and small in women. Our study shows significant changes in the spatiotemporal and kinetic gait parameters when carrying police equipment for both men and women. Although the effect sizes are trivial to small, carrying police equipment of ≈3.5 kg may have a negative impact on gait characteristics in first-year police officers.
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NewsBot · Sep 4, 2020

Effects of Three Modest Levels of Proximal Loading on Marathon Pace Running
Economy
JACKSON W. GADDIE et al
International Journal of Exercise Science 13(7): 1120-1131, 2020.

This study examined the effect of
modest increases in proximal body mass on running economy expressed as metabolic cost (MC). External loads of
1.6 (L), 2.4 (M), and 3.2 kg (H) were added to the anterior and posterior torso region of male (n = 18) and female (n
= 18) runners using a double-layered compression garment with gel inserts. MC was evaluated using stoichiometry
equations of data collected via indirect calorimetry. Data was collected during four, 5-min running bouts at
marathon pace for the 3 load levels and an unloaded state (CON). When data from both sexes were combined, MC
for CON (13.2 ± 2.7) was lower (p < 0.05) versus L (13.5 ± 2.6), M (13.6 ± 2.6), and H (13.7 ± 2.6 kcal/min), but L did
not differ from CON when data was analyzed for each sex. Male runners exhibited stepped increases in MC across
loads and a weak-moderate relationship (r = 0.37; p < 0.01) between percentage change in absolute MC and
increased percent body mass. A prediction model for MC (∆% kcal/min = 0.98(∆% body mass) – 0.91; SEE = ± 2.5%)
was developed. For female runners, L increased MC by ~3.5% above CON, but no differentiation was found among
L, M, and H, limiting the development of a prediction equation for females. Modest increases in body mass can
produce detectable and potentially important levels of running economy impairment, but the relationship between
changes in body mass and RE are complex, particularly in regards to sex.
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