A moderate acute increase in physical activity enhances nutritive flow and the muscle protein anabolic response to mixed nutrient intake in older adults.
Level 2 - randomized trial
Randomized crossover trial
PubMed 22572647 · doi:10.3945/ajcn.111.020800
What was done
Six older adults (aged 70 ± 3 years, BMI 25 ± 1 kg/m²) completed a randomized crossover trial comparing the acute effects of an aerobic exercise bout versus a normal sedentary lifestyle condition. Following each condition, responses to essential amino acid (EAA) plus sucrose ingestion were assessed, including blood flow, microvascular perfusion, insulin signaling, and muscle protein kinetics (phenylalanine delivery, net balance, and muscle protein synthesis).
What was found
No differences between conditions were present in the basal state. The change from baseline during EAA+sucrose consumption in blood flow, muscle perfusion, phenylalanine delivery, net balance, and muscle protein synthesis was significantly higher after exercise than after the control condition (P < 0.05). Insulin signaling increased during EAA+sucrose ingestion in both groups (P < 0.05). Numerical values and effect sizes were not provided in the abstract.
Why it matters
This study indicates that prior acute aerobic exercise enhances the anabolic response to nutrient ingestion in older adults, likely by improving vasodilation and nutrient delivery rather than modulating insulin signaling.
Limits
The sample size is extremely small (n = 6). The abstract omits exact numerical values, effect sizes, variance, and participant sex breakdown, and it only examines acute metabolic responses rather than chronic functional or muscle mass outcomes.
Cited by
- supports Performing an exercise session prior to food intake restores the postprandial muscle protein synthesis response in older adults to an almost completely normal level.