Collagen Protein Ingestion during Recovery from Exercise Does Not Increase Muscle Connective Protein Synthesis Rates.
Level 2 - randomized trial
Randomized, double-blind, parallel-group controlled trial
PubMed 37202878 · doi:10.1249/MSS.0000000000003214
What was done
In a randomized, double-blind, parallel-group trial, 45 young male (n = 30) and female (n = 15) recreational athletes (age 25 ± 4 yr, BMI 24.1 ± 2.0 kg·m⁻²) received primed continuous intravenous infusions of L-[ring-¹³C₆]-phenylalanine and L-[3,5-²H₂]-tyrosine. Following a single resistance exercise session, participants were randomized to ingest 30 g whey protein (n = 15), 30 g collagen protein (n = 15), or a noncaloric placebo (n = 15). Blood and muscle biopsies were sampled over a 5-h recovery period to evaluate myofibrillar and muscle connective protein synthesis rates.
What was found
Protein ingestion increased circulating plasma amino acid concentrations (P < 0.05). Plasma leucine and essential amino acid rises were greater in whey compared with collagen, while plasma glycine and proline rose more in collagen compared with whey (P < 0.05). Myofibrillar protein synthesis rates were 0.041 ± 0.010%·h⁻¹ (whey), 0.036 ± 0.010%·h⁻¹ (collagen), and 0.032 ± 0.007%·h⁻¹ (placebo), with only whey significantly higher than placebo (P < 0.05). Muscle connective protein synthesis rates were 0.072 ± 0.019%·h⁻¹ (whey), 0.068 ± 0.017%·h⁻¹ (collagen), and 0.058 ± 0.018%·h⁻¹ (placebo), with no significant differences between groups (P = 0.09).
Why it matters
This study shows that postexercise collagen ingestion does not enhance muscle connective tissue synthesis or myofibrillar protein synthesis during early recovery, challenging claims that collagen supplementation selectively benefits intramuscular connective tissue remodeling.
Limits
The sample size was small (15 participants per arm), and the study assessed only acute 5-hour recovery following a single exercise bout. It measured intramuscular connective tissue synthesis rather than tendon or ligament synthesis, and long-term training adaptations were not evaluated.