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Diet-Controlled Whey Protein Supplementation: Mitigating Serum Creatine Kinase Levels After Continuous Resistance Exercise.

  • 2025-08-25
  • Journal of the American Nutrition Association 45(2)
    • Chae-Been Kim
    • Dohyun Ahn
    • Ji-Been Kim
    • Hyoung-Su Park
    • Hye-Jin Kim
    • Jung-Jun Park

Study Design

Type
Randomized Controlled Trial (RCT)
Population
Thirty-six men
Methods
Cross-sectional study with repeated measures intervention; randomly assigned to a protein supplement group (PSG) or a placebo group (CON); consumed three packed meals with protein supplement or placebo daily; resistance exercise (60% 1-RM intensity) for 60 min over 6 consecutive days
Blinding
Double-blind
Duration
1 week
Funding
Unclear

Objective

As awareness of the health benefits of resistance exercise grows, an increasing number of people are participating, but eccentric movements in such exercises can cause muscle damage. This study aimed to investigate the effects of whey protein supplementation on resistance exercise-induced serum creatine kinase (CK) increase.

Design

Cross-sectional study with repeated measures intervention lasting 1 week.

Methods

Thirty-six men were randomly assigned to a protein supplement group (PSG) or a placebo group (CON). Participants consumed three packed meals with protein supplement or placebo daily. Resistance exercise (60% 1-RM intensity) occurred for 60 min over 6 consecutive days. Blood was collected at baseline, within 1-h post-exercise for 6 days, and 24 h after the final session.

Results

There was a significant group-by-time interaction (p = 0.049). In PSG, there were no significant changes in serum CK levels at any consecutive time points. However, a significant increase in serum CK levels was observed exclusively in CON from 0 to 24 h after exercise (from 551.4 ± 323.4 to 1244.8 ± 1203.6, p = 0.036), and also from 24 to 48 h after exercise (from 1244.8 ± 1203.6 to 7480.2 ± 9173.0, p = 0.044). Additionally, a significant decrease was noted only in CON from 96 to 120 h after exercise (from 12696.3 ± 10438.4 to 9957.8 ± 9176.6, p = 0.023). Serum CK levels on the last day were lower in PSG than in CON (p = 0.023).

Conclusion

In conclusion, whey protein supplementation may have a positive effect in mitigating the serum CK increase induced by six consecutive days of resistance exercise.

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