Always interesting to hear comments of “upper body muscles will weigh a player down”. This neglects the role of the upper body in running, which has been researched and found to contribute in a high degree. Neglecting upper body development may even make your player slower!

Removal of arm swing when running has been found to impact metabolic demand by as much as 13%. Arellano & Kram (2014) indicate the need for arm swing for metabolic economy and to minimise torso rotation.

In sprinting, although labelled a “contentious” area, the arms may contribute up to as much as 10% vertical propulsive forces (Macadam et al., 2018), as well as for balance. They are also believed to help thrust the athlete forward in sprints.

Therefore, neglecting the development of the upper body can potentially negatively impact the performance of running, regardless of the sport.

muscle = weight
weight (via muscle) ≠ Slower

Be great to hear opinions / thoughts

Would love to hear thoughts from the wizards of this area (and anyone else for that matter)! @Jonnie_Mechanic @rich_blagrove @RICH_AgilityLab @stevemagness @griffperftrain @FransBoschBook