Graded running

NewsBot · May 13, 2020

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Fatigue associated with prolonged graded running.
Giandolini M et al
Eur J Appl Physiol. 2016 Oct;116(10):1859-73

Scientific experiments on running mainly consider level running. However, the magnitude and etiology of fatigue depend on the exercise under consideration, particularly the predominant type of contraction, which differs between level, uphill, and downhill running. The purpose of this review is to comprehensively summarize the neurophysiological and biomechanical changes due to fatigue in graded running. When comparing prolonged hilly running (i.e., a combination of uphill and downhill running) to level running, it is found that (1) the general shape of the neuromuscular fatigue-exercise duration curve as well as the etiology of fatigue in knee extensor and plantar flexor muscles are similar and (2) the biomechanical consequences are also relatively comparable, suggesting that duration rather than elevation changes affects neuromuscular function and running patterns. However, 'pure' uphill or downhill running has several fatigue-related intrinsic features compared with the level running. Downhill running induces severe lower limb tissue damage, indirectly evidenced by massive increases in plasma creatine kinase/myoglobin concentration or inflammatory markers. In addition, low-frequency fatigue (i.e., excitation-contraction coupling failure) is systematically observed after downhill running, although it has also been found in high-intensity uphill running for different reasons. Indeed, low-frequency fatigue in downhill running is attributed to mechanical stress at the interface sarcoplasmic reticulum/T-tubule, while the inorganic phosphate accumulation probably plays a central role in intense uphill running. Other fatigue-related specificities of graded running such as strategies to minimize the deleterious effects of downhill running on muscle function, the difference of energy cost versus heat storage or muscle activity changes in downhill, level, and uphill running are also discussed.
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NewsBot · May 13, 2020

Biomechanics of Graded Running: Part I ‐ Stride Parameters, External Forces, Muscle Activations
Gianluca Vernillo Aaron Martinez Michael Baggaley Arash Khassetarash Marlene Giandolini Nicolas Horvais W. Brent Edwards Guillaume Y. Millet
First published: 12 May 2020

Biomechanical alterations with graded running have only been partially quantified, and the potential interactions with running speed remain unclear. We measured spatiotemporal parameters, ground reaction forces and leg muscle activations (EMG) in nineteen adults (10F/9M) running on an instrumented treadmills at 2.50, 3.33 and 4.17 m·s‐1 and 0, ±5º, and ±10º. Step frequency illustrated a significant speed × grade interaction (P < 0.001) and was highest (+3%) at the steepest grade (+10º) and fastest speed (4.17 m·s‐1) when compared to level running (LR) at the same speed. Significant interaction was also observed for ground reaction forces (all P ≤ 0.047). Peak ground reaction forces in the normal direction increased with running speed during downhill running (DR) only (+9% at ‐10º and 4.17 m·s‐1). Impulse in the normal direction decreased at fastest speed and steepest DR (‐9%) and uphill running (UR) (‐17%) grades. Average normal loading rate increased and decreased at fastest speed and steepest DR (+52%) and UR (‐28%) grades, respectively. Negative parallel impulse increased and decreased at fastest speed and steepest DR (+166%) and UR (‐90%), respectively. Positive parallel impulse decreased and increased at fastest speed and steepest DR (‐75%) and UR (+111%), respectively. EMG showed comparable u‐shaped curves across the grades investigated, although only a change in vastus lateralis and tibilias anterior activity was detectable at the steepest grades and fastest speed. Overall, running grade and speed significantly influences spatiotemporal parameters, ground reaction forces, and muscle activations.
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NewsBot · Jun 4, 2020

Biomechanics of Graded Running: Part II ‐ Joint Kinematics and Kinetics
Arash Khassetarash Gianluca Vernillo Aaron Martinez Michael Baggaley Marlene Giandolini Nicolas Horvais Guillaume Y. Millet W. Brent Edwards
02 June 2020

Compared to level running (LR), different strategies might be implemented by runners to cope with specific challenges of graded running at different speeds. The changes in joint kinetics and kinematics associated with graded running have been investigated but their interactions with speed are unknown. Nineteen participants ran on an instrumented treadmill at five grades (0°, ±5° and ±10°) and three speeds (2.50, 3.33 and 4.17 m·s‐1) while 3D motion and forces were recorded. Three speed × five grade repeated measures ANOVA was used to analyze kinetic and kinematic variables. A speed × grade interaction was observed for hip range of motion (ROM). Downhill running (DR) at fastest speed did not reduce ROM at the hip, compared to LR. Compared to LR, it was observed that the hip joint was responsible for a greater contribution of energy generation while running at the fastest speed at +10°. Speed × grade interactions were also observed for the energy absorption, peak moment, and peak power at the knee. Contrary to LR, running faster during UR did not require higher peak power at the knee. Finally, DR at the fastest speed did not increase peak negative power at the knee compared to LR. This study demonstrates that ankle, knee, and hip joint kinetics depend on speed and grade of running while the effect of grade on joint kinematics was not substantially modulated by speed.
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NewsBot · Jun 24, 2020

Physiological factors determining downhill vs uphill running endurance performance
Marcel Lemire et al
JASMS: June 20, 2020

Objectives
Recent studies investigated the determinants of trail running performance (i.e., combining uphill (UR) and downhill running sections (DR)), while the possible specific physiological factors specifically determining UR vs DR performances (i.e., isolating UR and DR) remain presently unknown. This study aims to determine the cardiorespiratory responses to outdoor DR vs UR time-trial and explore the determinants of DR and UR performance in highly trained runners.
Design
Randomized controlled trial.
Method
Ten male highly-trained endurance athletes completed 5-km DR and UR time-trials (average grade: ±8%) and were tested for maximal oxygen uptake, lower limb extensor maximal strength, local muscle endurance, leg musculotendinous stiffness, vertical jump ability, explosivity/agility and sprint velocity. Predictors of DR and UR performance were investigated using correlation and commonality regression analyses.
Results
Running velocity was higher in DR vs UR time-trial (20.4 ± 1.0 vs 12.0 ± 0.5 km h −1, p < 0.05) with similar average heart rate (95 ± 2% vs 94 ± 2% maximal heart rate; p > 0.05) despite lower average V̇O 2 (85 ± 8% vs 89 ± 7% V̇O 2max; p < 0.05). Velocity at V̇O 2max (vV̇O 2max) body mass index (BMI) and maximal extensor strength were significant predictors of UR performance ( r 2 = 0.94) whereas vV̇O 2max, leg musculotendinous stiffness and maximal extensor strength were significant predictors of DR performance ( r 2 = 0.84).
Conclusions
Five-km UR and DR running performances are both well explained by three independent predictors. If two predictors are shared between UR and DR performances (vV̇O 2max and maximal strength), their relative contribution is different and, importantly, the third predictor appears very specific to the exercise modality (BMI for UR vs leg musculotendinous stiffness for DR).
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NewsBot · Jul 28, 2020

Steep (30°) uphill walking vs. running: COM movements, stride kinematics, and leg muscle excitations
Clarissa S Whiting et al
Eur J Appl Physiol. 2020 Jul 23

Purpose: We sought to biomechanically distinguish steep uphill running from steep uphill walking and explore why athletes alternate between walking and running on steep inclines.

Methods: We quantified vertical center of mass (COM) accelerations and basic stride parameters for both walking and running at a treadmill speed of 1.0 m/s on the level and up a 30° incline. We also investigated how electromyography (EMG) of the gluteus maximus (GMAX), vastus medialis (VM), medial gastrocnemius (MG), and soleus (SOL) muscles differ between gaits when ascending steep hills.

Results: The vertical COM accelerations for steep uphill walking exhibited two peaks per step of magnitude 1.47 ± 0.23 g and 0.79 ± 0.10 g. In contrast, steep running exhibited a single peak per step pattern with a magnitude of 1.81 ± 0.15 g. Steep uphill running exhibited no aerial phase, 40% faster stride frequency, and 40% shorter foot-ground contact time compared to steep uphill walking but similar leg swing times. SOL showed 36% less iEMG per stride during steep uphill running versus steep uphill walking, but all other EMG comparisons between steep running and walking were not significantly different.

Conclusions: Multiple biomechanical variables clearly indicate that steep uphill running is a distinctly different gait from steep uphill walking and is more similar to level running. The competing desires to minimize the energetic cost of locomotion and to avoid exhaustion of the SOL may be a possible explanation for gait alternation on steep inclines.
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NewsBot · Oct 6, 2020

Kinematic and mechanical changes during a long half-marathon race: males and females at uphill/downhill slopes
Francesca NARDELLO et al
The Journal of Sports Medicine and Physical Fitness 2020 Sep 16

BACKGROUND: The aim of this study was to compare the running kinematics and the spring mass model mechanics over an entire half-marathon race in male and female athletes on different slopes (- 7%, 0% and +7%).
METHODS: 59 recreational runners (39 males and 20 females) participated in this study. Their running steps at own best self-selected speed were video recorded during a half-marathon (i.e. in ecological conditions): the kinematic variables (i.e. running speed, stride length and frequency, contact and flight time) were calculated, as well as the spring-mass characteristics (i.e. leg and vertical stiffness) of their running steps.
RESULTS: Males were able to run with greater speeds and lengths compared to females (P < 0.001) but with lower flight times (P < 0.05), and they reached higher values of both leg and vertical stiffness (P < 0.001). During downhill running, step lengths were larger compared to the level and the uphill (+6%) whereas frequencies slightly decreased (-2%), and aerial times were the greatest ones (+17%). During uphill running, contact times were slightly higher compared to other conditions (+3%), and leg stiffness reached the lowest values (-8%).
CONCLUSIONS: This study confirmed that there are important alterations in running steps in function of sex and surface slope. Importantly, the response to fatigue (i.e. alterations with the covered distance) does not alter these sex differences and is therefore independent of the sloped conditions.
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NewsBot · Oct 14, 2020

Downhill Running: What Are The Effects and How Can We Adapt? A Narrative Review
Bastien Bontemps, Fabrice Vercruyssen, Mathieu Gruet & Julien Louis
Sports Medicine (2020)

Downhill running (DR) is a whole-body exercise model that is used to investigate the physiological consequences of eccentric muscle actions and/or exercise-induced muscle damage (EIMD). In a sporting context, DR sections can be part of running disciplines (off-road and road running) and can accentuate EIMD, leading to a reduction in performance. The purpose of this narrative review is to: (1) better inform on the acute and delayed physiological effects of DR; (2) identify and discuss, using a comprehensive approach, the DR characteristics that affect the physiological responses to DR and their potential interactions; (3) provide the current state of evidence on preventive and in-situ strategies to better adapt to DR. Key findings of this review show that DR may have an impact on exercise performance by altering muscle structure and function due to EIMD. In the majority of studies, EIMD are assessed through isometric maximal voluntary contraction, blood creatine kinase and delayed onset muscle soreness, with DR characteristics (slope, exercise duration, and running speed) acting as the main influencing factors. In previous studies, the median (25th percentile, Q1; 75th percentile, Q3) slope, exercise duration, and running speed were − 12% (− 15%; − 10%), 40 min (30 min; 45 min) and 11.3 km h−1 (9.8 km h−1; 12.9 km h−1), respectively. Regardless of DR characteristics, people the least accustomed to DR generally experienced the most EIMD. There is growing evidence to suggest that preventive strategies that consist of prior exposure to DR are the most effective to better tolerate DR. The effectiveness of in-situ strategies such as lower limb compression garments and specific footwear remains to be confirmed. Our review finally highlights important discrepancies between studies in the assessment of EIMD, DR protocols and populations, which prevent drawing firm conclusions on factors that most influence the response to DR, and adaptive strategies to DR.
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NewsBot · Feb 15, 2022

Elite Road vs. Trail Runners
Comparing Economy, Biomechanics, Strength, and Power
Sabater Pastor, Frederic; Besson, Thibault; Berthet, Marilyne; Varesco, Giorgio; Kennouche, Djahid; Dandrieux, Pierre-Eddy; Rossi, Jeremy; Millet, Guillaume Y.
Journal of Strength and Conditioning Research: February 10, 2022 - Volume - Issue -

The purpose of this study was to determine the differences between road (ROAD) vs. trail (TRAIL) elite runners in terms of force-velocity profile (FVP), running biomechanics, lower-limb maximal isometric strength, cost of running (Cr), and training. Seventeen male elite athletes (10 TRAIL and 7 ROAD) participated in this study. Force-velocity profile was measured using a 2-sprint test on a cycle ergometer. Strength was assessed with a dynamometer measuring isometric maximum voluntary torque of the knee extensors and knee flexors. Biomechanics parameters (running kinematics and stiffness) were measured, and Cr was calculated at 10 and 14 km·h−1 at 0% slope and at 10 km·h−1 on a 10% slope on a treadmill. Athletes also reported their training duration during the previous year. Theoretical maximal torque (F0) and maximal power (Pmax) in the FVP were higher for TRAIL vs. ROAD (122 ± 13 vs. 99 ± 7 N·m, p = 0.001; and 726 ± 89 vs. 626 ± 44 W; p = 0.016). Cost of running was higher for TRAIL compared with ROAD on flat at 14 km·h−1 (4.32 ± 0.22 vs. 4.06 ± 0.29 J·kg−1·m−1; p = 0.047) but similar at 10 km·h−1 and uphill. No differences were found in maximal isometric strength or running biomechanics. ROAD spent 81% more time training than TRAIL (p = 0.0003). The specific training (i.e., “natural” resistance training) performed during graded running in trail runners and training on level surface at high speed may explain our results. Alternatively, it is possible that trail running selects stronger athletes because of the greater strength requirements of graded running.
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NewsBot · Feb 21, 2022

EFFECT OF FATIGUE AND GRADED RUNNING ON KINEMATICS AND KINETICS PARAMETERS IN TRIATHLETES
Greyce Any Sousa Mateus et al
Int J Sports Med. 2022 Feb 17

This study aimed to evaluate the effect of cycling-induced fatigue on subsequent running with different ground inclinations on triathletes. Twenty male triathletes ran on a treadmill at individual speeds, on three inclines: level (0%), 7% uphill (7%), and 7% downhill (-7%). Subsequently, the athletes performed an incremental ramp-to-exhaustion (RTE) protocol on an ergometric bicycle until task failure and repeated the running protocol (POST-RTE). During running and cycling was monitored perceived exertion (RPE) and heart rate (HR). Plantar pressure distribution, peak plantar pressure, total foot area, and ground contact time were measured by an in-shoe sensor. Analysis of variance showed that HR (p=0.001; η2=0.63) and RPE (p=0.001; η2=0.82 large effect) were higher in POST-RTE, without interactions between slopes and fatigue. The heel load showed difference between 0% and 7% and 7% and -7% (p=0.001; η2=0.44 large effect) with higher value in -7%. The midfoot showed differences between 0% and -7% with higher value in 0% (p=0.03; η2=0.15 small effect). The contact time showed interactions between fatigue and slopes with a higher value in POST-RTE. Coaches should be aware that training on the uphill and downhill surfaces can alter the plantar load on different foot parts.
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