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

PMID: 37543952
Journal: Journal of the International Society of Sports Nutrition
Published: 2023
Authors: 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.

## Population

- Male trained swimmers.
- Sample size: 20
- Age: 23.1 +/- 2.7 years
- Sex: Male
- Fitness level: Trained swimmers, 9 +/- 5 years experience
- Health status: Apparently healthy after screening

## Methodology

- Double-blind randomized controlled trial
- 2 weeks
- Swimming training and controlled nutrition environment
- Randomized and controlled study design.

## Protocol

- Swimming SIT plus pre-sleep whey protein.
- Modality: Swimming.
- Work intervals: 50 m all-out swim.
- Recovery: 1:1 passive recovery, plus 3 minutes between sets.
- Sets or repetitions: 2 sets of 12 sprints.
- Intensity: All-out.
- Session duration: Variable; included 20 minutes combined warmup/cooldown plus sprint and rest time.
- Frequency: 6 sessions/week.
- Program length: 2 weeks.
- Progression: None reported.
- Swimming SIT plus pre-sleep carbohydrate.
- Modality: Swimming.
- Work intervals: 50 m all-out swim.
- Recovery: 1:1 passive recovery, plus 3 minutes between sets.
- Sets or repetitions: 2 sets of 12 sprints.
- Intensity: All-out.
- Session duration: Same as intervention.
- Frequency: 6 sessions/week.
- Program length: 2 weeks.
- Progression: None reported.

## Outcomes

### Supplement
Status: no clear change
Protein did not improve damage or inflammation markers versus carbohydrate.

No meaningful between-group advantage reported

### Fitness
Status: improved
VO2peak and power measures improved in both groups.

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

### Inflammation
Status: mixed
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

## Practical 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 And Adherence

- 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.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/37543952/) (pubmed)
- [DOI](https://doi.org/10.1080/15502783.2023.2244478) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10405750/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.