EAA supplementation modestly reduced soreness and was associated with faster recovery of muscle swelling but did not influence tendon morphology within 72 hours following eccentric plantar flexor exercise.
The eccentric plantar flexor protocol successfully induced exercise-induced muscle damage across all groups.
EAA supplementation attenuated perceived muscle soreness at 24 hours post-exercise compared with placebo.
Calf muscle swelling returned to baseline by 72 hours in the EAA group but remained elevated in the placebo group.
Achilles tendon thickness decreased immediately post-exercise but was not influenced by EAA supplementation.
The study enrolled 36 recreationally active males randomized to three conditions: EAA, placebo, or control.
Pain pressure threshold was reduced following the eccentric exercise protocol but was not reported to be significantly influenced by EAA supplementation.
This research suggests that taking essential amino acid (EAA) supplements around an intense bout of eccentric calf exercise — the kind that causes significant muscle soreness and damage — may offer modest recovery benefits compared to a placebo. In this randomized controlled trial of 36 young active men, those who took 10 grams of EAAs before, after, and during the 72-hour recovery period reported less muscle soreness at the 24-hour mark and showed faster resolution of calf muscle swelling, with swelling returning to normal by 72 hours in the EAA group while still remaining elevated in those who took a placebo (maltodextrin). However, EAA supplementation did not appear to affect the Achilles tendon, which showed a slight decrease in thickness immediately after exercise that was the same across all groups. The eccentric exercise protocol was effective at producing classic signs of muscle damage — increased soreness, swelling, and tenderness to pressure — confirming the protocol worked as intended. The control group (no supplement) was also included to help distinguish true supplement effects from those of simply consuming any substance. This research suggests that EAAs may help reduce soreness and speed up the resolution of muscle swelling after damaging exercise, but the benefits appear modest and may not extend to tendon recovery within a 72-hour window. These findings could be relevant for athletes or active individuals seeking nutritional strategies to support recovery after intense lower-leg exercise, though the effects were described as modest and limited to specific markers of recovery.
Upload your bloodwork. We'll cross-reference your results against this study and 4,700 others.
Upload Your LabsVasenina E, Adams J, Williams F, H O'Connell T, Knuppel A, Moriarty K, et al.. (2026). Effects of essential amino acid supplementation on musculotendinous recovery following eccentric plantar flexor exercise: a randomized controlled trial.. Journal of the International Society of Sports Nutrition. https://doi.org/10.1080/15502783.2026.2726619