Postabsorptive and postprandial myofibrillar protein synthesis rates at rest and after resistance exercise in women with postmenopause.
Level 2 - randomized trial
Controlled acute physiological human trial with unilateral within-subject exercise control
PubMed 38385186 · doi:10.1152/japplphysiol.00886.2023
What was done
Sixteen postmenopausal females (age 60 ± 7 years, BMI 26 ± 12 kg·m⁻²) completed an acute bout of unilateral resistance exercise followed by ingestion of either a fortified whey protein supplement (WHEY) or water. Participants received primed continuous infusions of L-[ring-¹³C₆]phenylalanine with bilateral muscle biopsies taken before and at 2 h and 4 h post-ingestion from both exercised and non-exercised legs. The authors measured myofibrillar protein synthesis (MPS) rates, anabolic signaling phosphorylation (p70S6K, AMPKα, YAP Ser127), and baseline postabsorptive MPS compared against young/premenopausal females.
What was found
Resistance exercise alone (water condition) transiently elevated MPS above baseline during the 0–2 h window (P = 0.007). Whey protein ingestion following exercise led to an MPS increase during the 2–4 h window (P = 0.005). Neither condition showed an enhancement in cumulative 0–4 h MPS following resistance exercise. The non-exercised leg showed no significant MPS differences at 0–2 h, 2–4 h, or 0–4 h (all P > 0.05). Signaling markers (p70S6K, AMPKα, total/phosphorylated YAP) did not change. Baseline postabsorptive MPS was significantly lower in premenopausal compared with postmenopausal females (P = 0.023).
Why it matters
Much of the literature on anabolic resistance and muscle protein synthesis has centered on male cohorts. These data characterize female-specific anabolic responses, showing temporal shifts without cumulative 4-hour MPS enhancement after resistance exercise in postmenopausal women.
Limits
Small sample size (n = 16 postmenopausal females); sample details for the young premenopausal comparison group are not specified in the abstract; measurements were restricted to an acute 4-hour postprandial/post-exercise window, which cannot establish chronic hypertrophy or functional strength changes.
Cited by
- supports After menopause, women's muscles become resistant to building and begin to atrophy.
- supports Postmenopausal women experience anabolic resistance, where muscle tissue resists signals for growth and synthesis.