Postexercise Cooling Lowers Skeletal Muscle Microvascular Perfusion and Blunts Amino Acid Incorporation into Muscle Tissue in Active Young Adults.
Level 2 - randomized trial
Individual within-subject randomized controlled trial with contralateral limb control
PubMed 40249909 · doi:10.1249/MSS.0000000000003723
What was done
Twelve active young males (mean age 24 ± 4 years) completed a single resistance exercise session followed by 20 minutes of leg water immersion, with one leg immersed in cold water (8°C) and the contralateral leg in thermoneutral water (30°C). Participants then ingested a recovery beverage containing 20 g free amino acids, 45 g carbohydrates, and 0.25 g L-[ring-13C6]-phenylalanine tracer. Microvascular perfusion of the vastus lateralis muscle was measured using contrast-enhanced ultrasound at rest, immediately after immersion, and at 60 and 180 minutes post-ingestion. Bilateral vastus lateralis muscle biopsies were taken at 240 minutes post-ingestion to assess amino acid tracer incorporation.
What was found
Microvascular blood volume was significantly lower in the cold versus control leg immediately after immersion (1.24 ± 0.82 vs 3.13 ± 1.64 video intensity, P < 0.001) and remained lower at 60 minutes (0.90 ± 0.84 vs 1.53 ± 0.98, P < 0.05) and 180 minutes (2.10 ± 2.53 vs 2.77 ± 2.81 video intensity, P < 0.05). Exogenous amino acid incorporation into muscle protein was lower in the cold versus control leg (0.011 ± 0.004 vs 0.016 ± 0.005 mole percent excess, P < 0.001). The between-leg difference in amino acid incorporation was positively correlated with the between-leg difference in microvascular blood volume during recovery (r = 0.65, P < 0.05).
Why it matters
These findings identify impaired microvascular perfusion as a key physiological mechanism explaining why postexercise cold-water immersion attenuates amino acid incorporation into muscle protein.
Limits
The study was small (n = 12) and included only young adult males. It examined an acute single-session response, so long-term effects on muscle hypertrophy, strength, and chronic training adaptations were not assessed.
Cited by
- supports Deliberate cold exposure immediately after resistance strength training blunts muscle hypertrophy and anabolic signaling, as shown by Luc van Loon's group.