PMID 37543952

Research
All papers

Effects of pre-sleep protein supplementation on plasma markers of muscle damage and inflammatory cytokines resulting from sprint interval training in trained swimmers

Wu C, Deng J, Gao C

Question

Does pre-sleep whey protein supplementation reduce muscle damage and inflammatory cytokine responses during a two-week swimming sprint interval training program?

Summary

In 20 male trained swimmers, two weeks of very frequent swimming sprint interval training improved aerobic and power measures but not 200 m performance. Taking whey protein before sleep did not reduce creatine kinase or inflammatory cytokine responses compared with carbohydrate.

Methodology

  • Male trained swimmers.
  • 20 participants.
  • Swimming.
  • Work intervals: 50 m all-out swim.
  • Recovery: 1:1 passive recovery, plus 3 minutes between sets.
  • Intensity: All-out.
  • Variable; included 20 minutes combined warmup/cooldown plus sprint and rest time.
  • 6 sessions/week.
  • 2 weeks.
  • Double-blind randomized controlled trial
  • Muscle damage, Inflammation, and Performance were tracked.

Outcomes

Supplement

Protein did not improve damage or inflammation markers versus carbohydrate.

No meaningful between-group advantage reported

No clear change

Fitness

VO2peak and power measures improved in both groups.

VO2peak PRO +3.7% p=.002; CHO +2.7% p=.007

Improved

Inflammation

Cytokines rose acutely after sessions; IL-6/IL-10 ratio was lower after training.

48 h post-final IL-6/IL-10 ratio p<0.04

Mixed

Insights

  • A short high-frequency SIT block can improve physiology in trained swimmers.
  • Pre-sleep protein should not be claimed to reduce SIT muscle damage based on this study.
  • All-out sprint blocks require recovery planning.

Limitations

  • Small sample.
  • Male trained swimmers only.
  • Short two-week duration.
  • Sleep was not closely monitored.
  • Outcomes relied on plasma markers and swimming-specific performance.

Safety

  • Adverse events were not directly reported.
  • The SIT program caused acute rises in creatine kinase and inflammatory cytokines, indicating muscle-damage and inflammatory stress.
  • Participants were trained swimmers, screened for disease, diet-controlled, and restricted from additional training.