Lifelong strength training mitigates the age-related decline in efferent drive

Recently we documented age-related attenuation of efferent drive to contracting skeletal muscle. It remains elusive if this indication of reduced muscle strength is present with lifelong strength training. For this purpose, we examined evoked potentials in the calf muscles of 11 (71±4years) strength trained master athletes (MA) contrasted to 10 (71±4years) sedentary (SO) and 11 (73±6years) recreationally active (AO) old subjects, as well as 9 (22±2years) young controls. As expected, MA had higher leg press maximal strength (MA: 185±32kg; AO: 128±15kg; SO: 106±11kg; young: 147±22kg, p<0.01) and rate of force development (MA: 5588±2488N•s^-1; AO: 2156±1100N•s^-1; SO: 2011±825N•s^-1; young: 3663±1140N•s^-1, p<0.05) than the other groups. MA also exhibited higher m.soleus normalized V-waves during MVC (V_sup/M_sup: 0.28±0.15) than AO (0.13±0.06, p<0.01) and SO (0.11±0.05, p<0.01), yet lower than young (0.45±0.12, p<0.01). No differences were apparent between the old groups in H-reflex recorded at rest or during MVC (H_max/M_max; H_sup/M_sup), and all were lower (p<0.01) than young. MA (34.4±2.1ms) had shorter (p<0.05) H-reflex latency compared to AO (36.4±3.7ms) and SO (37.3±3.2ms), but longer (p<0.01) than young (30.7±2.0ms). Using interpolated twitch analysis MA (89±7%) had similar plantar flexion voluntary activation as young (90±6%), and this was higher (p<0.05), or tended to be higher (p=0.06-0.09) than SO (83±10%) and AO (84±5%). These observations suggest that lifelong strength training has a protective effect against age-related attenuation of efferent drive. In contrast, no beneficial effect seems to derive from habitual recreational activity, indicating that strength training may be particularly beneficial for counteracting age-related loss of neuromuscular function.

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