Neither myonuclear accretion nor a myonuclear domain size ceiling is a feature of the attenuated hypertrophic potential of aged human skeletal muscle

• DOI: 10.1007/s11357-022-00651-y
• Publication Date: 2022-09-09T12:37:36Z
• Authors: Matthew S. Brook; Daniel J. Wilkinson; Janelle Tarum; Kyle W. Mitchell; Jonathan L. Lund; Bethan E. Phillips; Nathaniel J. Szew...; Fawzi Kadi; Paul L. Greenhaff; Ken Smith; Philip J. Atherton
• Keywords: Male; 0301 basic medicine; Aging; 0303 health sciences; 03 medical and health sciences; Humans; Resistance Training; Hypertrophy; DNA; 10. No inequality; Muscle, Skeletal; Article; Aged

Abstract Ageing limits growth capacity of skeletal muscle (e.g. in response to resistance exercise), but the role satellite cell (SC) function driving this phenomenon is poorly defined. Younger (Y) (~ 23 years) and older (O) men 69 (normal-weight BMI) underwent 6 weeks unilateral exercise training (RET). Muscle biopsies were taken at baseline after 3-/6-week training. We determined size by fibre CSA (and type), SC number, myonuclei counts DNA synthesis (via D 2 O ingestion). At baseline, there no significant differences areas between Y O. RET increased type I area from both 3 (baseline: 4509 ± 534 µm , weeks; 5497 510 P < 0.05, 5402 352 0.05), whilst only (baseline 5120 403 5606 620 6017 482 0.05). However, II 4949 459 6145 484 ( 0.01), 5992 491 showed change 5210 410 5356 535 = 0.9), 5857 478 0.1). number with (younger: 2.47 0.16, 3.19 0.16 0.001), 3.70 0.29 0.0001); older: 2.29 0.09, 3.01 0.09 3.65 0.18 0.0001)). Similarly, 2.49 0.14, 3.31 0.21 3.86 2.43 0.12, 3.37 0.12 3.81 0.15 rates %.d −1 exhibited a main effect age discrimination. Declines addition do not underlie impaired humans, supporting ribosomal proteostasis impairments as we have previously reported.