Foot strengthening in trained athletes

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Effects of a forefoot strengthening protocol on explosive tasks performance and propulsion kinetics in athletes: a single-blind randomized controlled trial

• November 2024

DOI:10.1101/2024.11.06.24316826

Recently, Roman Tourillon has done some fascinating work on the foot/ankle complex, making a valuable overall contribution in this area. However, his forefoot strengthening methods seem to be only about half as effective as merely walking around in minimal shoes for 6 months and no more effective than the "gentle" exercises he seems to advocate against when training athletes ( 30% strength gains ). In short, the exercises used by Tourillon et al where not very effective at all.

Ironically, a method for producing really big foot strength gains ( up to 90% with 30 mins effort a week) may have been right in front of Tourillon all the time, his toe flexor measurement dynamometer.

The dynamometer is very similar in set up to the measurement/ strengthening system used by Goldmann et al, 2013, to produce rapid strength gains in toe flexor strength ( up to 90%), in sports students at Cologne University. Goldmann and his colleagues used an voluntary isometric contraction at 90% of maximum and found that the toe flexors where highly responsive to the strengthening method they employed.

The keys to the Goldmann set up, also present in the Tourillon measurement method, are to have the toes working in a dorsiflexed position and very importantly, in my opinion, to have some sort of restraint across the top of the foot to resists lifting of the arch as the toes develop torque. Goldmann and Tourillon used inelastic straps.

So, if Tourillon and his colleagues had worked out the maximum force each athlete could develop in their measuring device, then had them hold isometric contractions at 90% of that effort, and followed a similar protocol to Goldmann et al, then they would presumably have gotten far greater toe flexor gains than they did, and with much less effort.

Any thoughts ?

Link to article with Tourillon et al measurement set up

Training the foot to improve performance in sprinting, jumping and change of direction - Sportsmithsportsmith.co

 

In a recent article (1) Romain Tourillon wrote the following,

"We misunderstand the energetic and biomechanical roles of the different foot muscles during locomotion. Looking at all the foot strengthening protocols, we are in the era of “it’s all about intrinsic foot muscles” when it comes to foot strength and foot stiffness, as if they regulate the entire function of the foot complex. They don’t. "

I don't believe we have ever lived in an era when it was "all about the intrinsic foot muscles", we are really just coming out of an area when the intrinsic foot muscles were viewed being almost vestigial by some clinicians. There is a lot of interest in the IFM now, but this is probably because they have been largely ignored before and there is a lot of ground to make up.

I don't believe that anyone sees the main source of power in the foot as the intrinsic foot muscles, they are too small for that, but their actions are very necessary for the extrinsic foot muscles to do their jobs properly. This is particularly true of the muscles that keep the toes straight at the PIP joints namely the lumbricals and interossei.

Tourillon also wrote;

"By contrast, performance oriented studies showed the greatest effects from a high training volume (24-36 sessions of 30-40 min) [9–13] with either small or no effects on improving MTPj kinetics and force production during locomotion in competitive athletes [9,14,15]."

Reference 12 relates to a digit exerciser from Brigham Young University . Using the "exerciser" produced significantly faster acceleration and 20-40 yard speed than in a control group . The "exerciser" method was very different to those used by Tourillon et al .


(1)https://www.sportsmith.co/articles/...rce-production-transmission-and-distribution/

 

One problem that Tourillon et al seemed to run into during their research was exploring how exercise affects not just force production of the toe flexors but rate of force production, or toe flexor power.

I believe that an accurate measure of rate of force production will be difficult to record in an isometric set up such as the one used by Tourillon et al, because peoples instinct , when confronted by with an object they know to be immovable, is to ramp up force in a controlled manner to avoid injury.

When measuring lower limb power in a standing jump, for example, a person may be asked to stand on a force plate and jump upwards as far as they can . This they will do with no inhibition because they know they are going to move upwards. Place the same person in a framework that will prevent them moving upwards during a jumping task and they will likely produce less initial power since injury is a real possibility.

The set up used by Goldmann et al would be more suitable for measuring toe flexor power than that used by Tourillon because the platform on which the toes rest moves when force is applied.

Rate of production of toe flexor force is likely very important for maintaining balance when rapid responses are required.

Toe flexor strengthening studies tend to be centered around isometric exercises like the short foot exercise. When improvements in toe flexor power are targeted then systems which allow strengthening of "the moving toe", such as the Digit Exerciser from Brigham Young University, are likely better and can improve acceleration and reduce sprint times.