Abstract
Background: To investigate how anatomical cross-sectional area and volume of quadriceps and triceps surae muscles were affected by ageing, and by resistance training in older and younger men, in vivo. Methods: The old participants were randomly assigned to moderate (O55, n=13) or high-load (O80, n=14) training intervention (12 weeks; 3 times/week) corresponding to 55% or 80% of one repetition maximum, respectively. Young men (Y55, n=11) were assigned to the moderate-load training program. Each groups received the exact same training volume on triceps surae and quadriceps group (Reps x Sets x Intensity). The fitting polynomial regression equations for each of anatomical cross-sectional area-muscle length curves were used to calculate muscle volume (contractile content) before and after 12 weeks using magnetic resonance imaging scans.Results: Only Rectus femoris and medial gastrocnemius muscle showed a higher relative anatomical cross-sectional area in the young than the elderly on the proximal end. The old group displayed a higher absolute volume of non-contractile material than young men in triceps surae (+96%). After training, Y55, O55 and O80 showed an increase in total quadriceps (+4.3%; +6.7%; 4.2% respectively) and triceps surae (+2.8%; +7.5%; 4.3% respectively) volume. O55 demonstrated a greater increase on average gains compared to Y55, while no difference between O55 and O80 was observed.Conclusions: Muscle loss with aging is region-specific for some muscles and uniform for others. Equivalent training volume at moderate or high intensities induced no additional muscle volume gains for old men. These data suggest that physical exercise at moderate intensity (55 to 60% of one repetition maximum) can retain the aging related loss of muscle mass.Trial registration: CPP-2016/52 (France) and on Clinical Trials.gov (2016-A00534-47)
A 3D ultrasound platform to assess medial gastrocnemius lengthening during slow passive stretch in typically developing children and children with cerebral palsy
