Divergent serum metabolomic, skeletal muscle signaling, transcriptomic, and performance adaptations to fasted versus whey protein-fed sprint interval training.
Level 2 - randomized trial
Individual randomized controlled trial in humans
PubMed 34747202 · doi:10.1152/ajpendo.00265.2021
What was done
Healthy males underwent acute and short-term (3 weeks) sprint interval training (SIT) under three pre-exercise nutritional conditions: fasted, hydrolyzed whey protein (WPH), or whey protein concentrate (WPC). The investigators assessed serum metabolomics, skeletal muscle transcriptomics (including PGC-1α, PDK4, SIRT1, PPAR-δ, and CD36 mRNA), muscle intracellular signaling (pan-acetylation and PARP1 protein content), mitochondrial enzymatic activity, and exercise performance.
What was found
The abstract does not provide exact numerical data or statistical metrics. Pre-exercise protein intake did not alter acute post-exercise increases in PGC-1α, PDK4, SIRT1, or PPAR-δ mRNA compared with fasting, though WPH altered CD36 mRNA expression. Pre-exercise protein attenuated acute exercise-induced increases in muscle pan-acetylation and PARP1 protein content. After 3 weeks of SIT, mitochondrial enzymatic activity and performance improvements were similar across all nutritional groups, while resting muscle acetylation status decreased in the WPH condition.
Why it matters
The findings indicate that consuming whey protein prior to sprint intervals alters specific acute metabolic and signaling pathways without blunting the chronic mitochondrial or performance adaptations typically observed with fasted training.
Limits
The abstract omits sample size, participant training status, protein dosage, and all exact numbers or confidence intervals. The trial included only males and had a short duration of 3 weeks, leaving longer-term adaptations and applicability to females uncharacterized.
Cited by
- contradicts Exercising in a fasted state increases mitochondrial adaptations compared to exercising fed.