The Effects of a High-Protein Diet on Markers of Muscle Damage Following Exercise in Active Older Adults: A Randomized, Controlled Trial.
Study Goal
The researchers aimed to determine if a higher protein diet (2.50 g·kg⁻¹·day⁻¹) was more effective than a moderate protein diet (1.25 g·kg⁻¹·day⁻¹) in reducing markers of muscle damage and inflammation after strenuous exercise in older adults.
Results Summary
The study found no significant differences between the higher and moderate protein diets in attenuating muscle damage or inflammation markers post-exercise, except for a delayed peak in muscle soreness with the higher protein diet. Most inflammatory markers and muscle damage indicators remained unchanged by the intervention.
Population
Older adults (10 males and 8 females, age 57 ± 4 years).
Effective Dosage
2.50 g·kg⁻¹·day⁻¹ (higher protein) and 1.25 g·kg⁻¹·day⁻¹ (moderate protein).
Duration
48 hours.
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
higher protein diet (2.50 g·kg-1·day-1) | no change | indirect markers of muscle damage and inflammation | older adults | - | is not more effective than 1.25 g·kg-1·day-1 for attenuating | #1 |
strenuous exercise (140 squats) | decrease | maximal isometric voluntary contractions | older adults | - | decreased | #2 |
higher protein diet (2.50 g·kg-1·day-1) vs moderate protein diet (1.25 g·kg-1·day-1) | no change | maximal isometric voluntary contractions | older adults | - | did not differ between groups | #3 |
moderate protein diet (1.25 g·kg-1·day-1) | increase | muscle soreness | older adults | 44 ± 30 mm | peaked at 24 hr post | #4 |
higher protein diet (2.50 g·kg-1·day-1) | increase | muscle soreness | older adults | 70 ± 46 mm | peaked at 48 hr post | #5 |
higher protein diet (2.50 g·kg-1·day-1) vs moderate protein diet (1.25 g·kg-1·day-1) | no change | muscle soreness | older adults | - | no group differences were found | #6 |
strenuous exercise (140 squats) | decrease | monocytes | older adults | - | significantly decreased postexercise | #7 |
strenuous exercise (140 squats) | decrease | lymphocytes | older adults | - | significantly decreased postexercise | #8 |
strenuous exercise (140 squats) | increase | eosinophils | older adults | - | increased 24 hr postexercise | #9 |
strenuous exercise (140 squats) or higher protein diet intervention | no change | neutrophils | older adults | - | were unchanged | #10 |
strenuous exercise (140 squats) or higher protein diet intervention | no change | creatine kinase | older adults | - | were unchanged | #11 |
strenuous exercise (140 squats) or higher protein diet intervention | no change | interleukin-6 | older adults | - | were unchanged | #12 |
strenuous exercise (140 squats) or higher protein diet intervention | no change | C-reactive protein | older adults | - | were unchanged | #13 |
strenuous exercise (140 squats) or higher protein diet intervention | no change | monocyte chemotactic protein-1 | older adults | - | were unchanged | #14 |
strenuous exercise (140 squats) or higher protein diet intervention | no change | Brief Assessment of Mood Adapted | older adults | - | were unchanged | #15 |
PURPOSE: This study examined whether a higher protein diet following strenuous exercise can alter markers of muscle damage and inflammation in older adults. METHODS: Using a double-blind, independent group design, 10 males and eight females (age 57 ± 4 years; mass 72.3 ± 5.6 kg; height 1.7 ± 6.5 m) were supplied with a higher protein (2.50 g·kg-1·day-1) or moderate protein (1.25 g·kg-1·day-1) diet for 48 hr after 140 squats with 25% of their body mass. Maximal isometric voluntary contractions, muscle soreness, creatine kinase, Brief Assessment of Mood Adapted, and inflammatory markers were measured preexercise, and 24 hr and 48 hr postexercise. RESULTS: The maximal isometric voluntary contractions decreased postexercise (p = .001, ηp2=.421), but did not differ between groups (p = .822, ηp2=.012). Muscle soreness peaked at 24 hr post in moderate protein (44 ± 30 mm) and 48 hr post in higher protein (70 ± 46 mm; p = .005; ηp2=.282); however, no group differences were found (p = .585; ηp2=.083). Monocytes and lymphocytes significantly decreased postexercise, and eosinophils increased 24 hr postexercise (p < 0.05), but neutrophils, creatine kinase, interleukin-6, C-reactive protein, monocyte chemotactic protein-1, and Brief Assessment of Mood Adapted were unchanged by exercise or the intervention (p > .05). CONCLUSION: In conclusion, 2.50 g·kg-1·day-1 of protein is not more effective than 1.25 g·kg-1·day-1 for attenuating indirect markers of muscle damage and inflammation following strenuous exercise in older adults.