Blog by Dr. John Cronin
Note the wearable resistance (WR) on the arms. Do you think just putting it on can make you faster? What about longitudinal training adaptations? Is it better for acceleration or max velocity adaptation?
Whoa, we are getting ahead of ourselves and first it might be smart to establish how important the arms are during sprint running.
This is a contentious topic among sprint coaches and in the published literature, with general agreement that the arms do counterbalance the rotary momentum of the legs during sprint running, however, after that the debate begins due to the purported cancelling effects of simultaneous forward-backward action of the contralateral arms whilst sprinting upright.
However, the relative momentum of the horizontal component of both arms may not be cancelled during the start and early acceleration phase, and moreover, the arms may contribute up to 10% of the total vertical propulsive forces an athlete is capable of applying to the ground highlighting the importance of an efficient arm action.
So back to the start. Is arm loaded WR of any utility for speed development?
Forearm loading for sprinting 🏃♀️🏃
To follow up on the arm swing and bringing a little wearable resistance (WR) into the movement now. I have been involved in three peer reviewed articles looking at the effects of forearm loading in sprinting.
Let’s look at one study that involved loading the forearms of 14 track sprinters with 2% body mass (BM) and quantifying the changes over 30 m with force plates and 3D motion capture.
Some of the statistically significant findings were:
· No change in 0-30 m sprint times
· Increases in relative propulsive impulse (5.48%) over most phases and step length (4.01%) over 1st acceleration phase
· Over last acceleration phase, stride frequency was lower (-4.86%) and flight time (7.70%) and vertical impulse increased (4.12%)
We concluded, sprinting with forearm loads may be used to develop longer stride lengths by generating greater horizontal propulsion during early acceleration and promote alterations to step frequency and flight time imposed through greater vertical loading demands over the later phases of accelerated sprinting.
A training study is really needed to see where this goes.
Study: Uthoff, A. M., Nagahara, R., Macadam, P., Neville, J., Tinwala, F., Graham, S. P., & Cronin, J. B. (2020). Effects of forearm wearable resistance on acceleration mechanics in collegiate track sprinters. European journal of sport science, 20(10), 1346-1354.