Post-Exercise Whey Protein Supplementation: Effects on IGF-1, Strength, and Body Composition in Pre-Menopausal Women,...

Area of Science:

• Exercise Physiology
• Sports Nutrition
• Human Performance

Background:

• Untrained pre-menopausal women often seek effective training and nutritional strategies to enhance body composition and strength.
• The role of post-exercise protein supplementation in conjunction with combined training modalities requires further investigation.

Purpose of the Study:

• To assess the impact of post-exercise protein supplementation on insulin-like growth factor-1 (IGF-1), strength, and body composition.
• To evaluate the effects of a 12-week combined resistance and interval training program with varying protein intake.

Main Methods:

• Twenty-seven untrained pre-menopausal women were randomized into control or moderate protein groups.
• Participants completed 12 weeks of combined resistance and high-intensity interval cycle training.
• Measurements included IGF-1 concentration, 3-repetition maximum (3RM) strength, and dual-energy X-ray absorptiometry (DXA) for body composition.

Main Results:

• Both groups showed significant increases in strength (19-113%) and total lean mass (p=0.009).
• Post-exercise protein supplementation did not significantly alter IGF-1 levels or enhance strength and lean mass gains compared to the control group.
• The protein group had a significantly higher daily protein intake (~20 g/day).

Conclusions:

• Combined resistance and interval training effectively improves strength and lean mass in untrained women.
• Post-exercise protein supplementation appears to have a limited effect on these adaptations when added to a combined training program.
• IGF-1 was not found to be associated with strength or body composition changes in this cohort.