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Human muscle protein synthesis and breakdown during and after exercise
Vinod Kumar1, Philip Atherton, Kenneth Smith
1University of Nottingham, School of Graduate Entry Medicine and Health, Derby, UK.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|January 24, 2009
Summary
Exercise affects muscle protein turnover, with synthesis decreasing during exercise but increasing post-exercise with nutrient availability. Age and sex can influence these muscle adaptations.
Area of Science:
- Exercise physiology
- Muscle protein metabolism
Background:
- Skeletal muscle protein turnover is highly adaptable to exercise stimuli.
- Understanding acute and chronic responses to various exercise types is crucial.
Purpose of the Study:
- To synthesize current knowledge on muscle protein synthesis and breakdown alterations due to exercise.
- To examine the impact of nutrition, age, and sex on these responses.
- To review signaling protein activity related to muscle protein turnover control.
Main Methods:
- Literature review and synthesis of existing research on exercise and muscle protein metabolism.
- Analysis of factors influencing muscle protein synthesis (MPS) and muscle protein breakdown (MPB).
- Examination of signaling pathways involved in regulating protein turnover.
Main Results:
- Exercise, both resistance and non-resistance, generally decreases MPS during the activity.
- Post-exercise, both MPS and MPB increase in a fasted state, leading to negative net balance.
- Positive net muscle protein balance requires increased amino acid availability, significantly boosting MPS.
- Insulin, stimulated by glucose, is more critical for inhibiting MPB than amino acids are for stimulating MPS.
- Exercise training can elevate basal muscle protein turnover, with specific fractions responding differently to acute exercise.
- Aging diminishes myofibrillar protein and anabolic signaling responses to resistance exercise.
- Young men and women show similar acute exercise responses, but older women may experience blunted responses compared to older men.
Conclusions:
- Muscle protein synthesis and breakdown are dynamically regulated by exercise, nutrition, age, and sex.
- Nutrient availability, particularly amino acids and glucose, plays a key role in achieving positive muscle protein balance post-exercise.
- Age-related declines and potential sex differences in older adults warrant further investigation regarding muscle adaptation to exercise.
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