The optimal protein dosing for increased rates of myofibrillar protein synthesis (MPS) and gains in fat-free mass (FFM) and strength in response to resistance training is regularly debated but the leucine content appears to be a strong determinant, as well as the frequency and timing of ingestion. Isotopic tracer studies indicate that leucine-rich whey protein is rapidly digested, promoting a protein anabolic response when ingestion takes place post-exercise and before sleep.
However, there is no clear consensus that protein supplementation before, during, and following eccentric resistance exercise reduces muscle damage and accelerates performance recovery.
A team of researchers from the US, France and China, conducted a randomised trial to compare pea protein, whey protein, and water-only supplementation on muscle damage, DOMS, inflammation (CRP), and exercise performance during a five-day period after a 90-minute whole-body eccentric exercise bout in non-athletic non-obese males (n = 92, ages 18–55 years).
The three daily acute pea and whey protein doses (0.3 g/kg) differed in leucine content but both provided amounts within the recommended leucine intake range of 700–3000 mg. Thus, they hypothesised that large daily doses (0.9 g/kg) of pea and whey proteins compared to water spread throughout each day of the 5-day period would counter exercise-induced muscle damage, DOMS, and performance decrements.
Their report, published in Nutrients, concludes: "High intake of whey protein for five days after intensive eccentric exercise mitigated the efflux of muscle damage biomarkers, with the intake of pea protein having an intermediate effect.
"The major amino acid for MPS is leucine, and the 35% lower level of leucine in pea compared to whey protein was likely a key factor explaining our results, especially within the context of the extensive muscle damage experienced in our untrained participants."
However, the authors also point out that muscle damage may be similar between whey and pea protein supplement groups when leucine and BCAA intake levels are comparable
"In general, future studies should consider using leucine-fortified pea protein isolate supplements or greater dose volumes to match the leucine and BCAA profile of whey protein isolate. Post-exercise mitigation of serum muscle damage biomarkers may be similar between whey and pea protein supplement groups in comparison to water when leucine and BCAA intake levels are comparable."
The team utilised a randomised parallel group design, and emphasised high amounts of supplemental whey and pea protein split into three doses per day for several days post-exercise.
The two protein sources (0.9 g protein/kg divided into three doses/day) were administered under double blind procedures. The eccentric exercise protocol induced significant muscle damage and soreness, and reduced bench press and 30-s Wingate performance.
Whey protein supplementation significantly attenuated post-exercise blood levels for biomarkers of muscle damage compared to water-only, with large effect sizes for creatine kinase and myoglobin during the fourth and fifth days of recovery; pea protein versus water supplementation had an intermediate non-significant effect; and no significant differences between whey and pea protein were found.
The authors note: "These data support the strategy of using three 0.3 g/kg doses per day of whey protein isolate during several days of recovery from intensive eccentric-based exercise to reduce serum levels of muscle damage biomarkers in untrained males.
"Supplementation with pea protein compared to water had an intermediate but non-significant effect, with no differences found between pea and whey proteins. The whey protein supplement had no influence on DOMS or exercise performance despite the lowering effect on serum muscle damage biomarkers, a finding that has been reported in other similar investigations. Thus exercise-induced leakage of muscle proteins, such as creatine kinase, myoglobin, and LDH, has not been strongly or consistently correlated with muscle performance and soreness."
Prior research on plant protein
Intake of plant protein has increased during the past two decades in part due to environmental advantages and the linkage to improved health and decreased all-cause mortality. One study showed that 50 g/day doses of pea or whey protein during a 12-week resistance training period resulted in similar increases in muscle thickness relative to the placebo.Few studies have evaluated the effect of plant protein ingestion on exercise-induced muscle damage. Supplementation with oat protein (25 g/day, 18 days) in one study was linked to a decrease in delayed onset of muscle soreness (DOMS), serum creatine kinase and myoglobin, and serum C-reactive protein (CRP) after an intense downhill treadmill run.
Nieman. D. C., et al
"Effects of Whey and Pea Protein Supplementation on Post-Eccentric Exercise Muscle Damage: A Randomised Trial"