Similar Muscle Recovery but Greater Soreness in Active Vegans on Low‐Protein Diets Compared to High‐Protein Omnivores Following Exercise‐Induced Damage

ABSTRACT

To assess whether a low‐protein vegan diet is associated with differences in recovery from exercise‐induced muscle damage (EIMD) in physically active individuals. Physically active vegans ( n  = 7) and omnivores ( n  = 7) underwent a lower‐body muscle damage protocol consisting of five sets of repetitions to failure using the Smith machine squat and leg press at 85% of one‐repetition maximum (1RM). Muscle damage and recovery were assessed at baseline, immediately post‐exercise, and at 24, 48, and 72 h post‐EIMD. Outcomes included serum concentrations of creatine kinase (CK) and lactate dehydrogenase (LDH), delayed‐onset muscle soreness (DOMS), countermovement jump (CMJ) performance, and range of motion (ROM). Habitual dietary intake was assessed using four 24‐h dietary recalls analysed via the Multiple Source Method (MSM) software. Participants demonstrated similar training volume across exercises and comparable hydration status. Protein intake was significantly lower in vegans (0.98 g/kg) compared to omnivores (2.14 g/kg), along with reduced intake of essential amino acids and, specifically, branched‐chain amino acids ( p  ≤ 0.05). CK levels increased immediately after EIMD and peaked at 24 h, remaining elevated relative to baseline in both groups ( p  ≤ 0.05). LDH levels rose immediately post‐exercise in both groups and were still elevated at 24 h ( p  ≤ 0.05). DOMS was markedly greater in vegans (+2.7 at 24 h; +2.6 at 72 h on VAS) than in omnivores at 24 and 72 h post‐exercise ( p  ≤ 0.05). While habitually active vegans and omnivores exhibited similar overall responses in muscle damage and recovery following intense resistance exercise, vegans experienced clinically meaningful increases in DOMS. These findings suggest that a low‐protein vegan diet may be associated with increased perceived muscle damage, without impairing acute functional recovery. For individuals following a vegan diet, these results highlight the importance of ensuring adequate protein intake and protein quality, including sufficient essential amino acids and branched‐chain amino acids, to potentially mitigate exercise‐induced muscle soreness and optimise recovery comfort.