STRENGTH TRAINING ALTERS CONTRACTILE PROPERTIES OF THE TRICEPS BRACHII IN MEN AGED 65-78 YEARS

Voluntary and electrically evoked contractile properties were studied in the triceps brachii following a 24-week dynamic stength training program in ten men aged 65-78 years. Eight men of a similar age were control subjects. A resistance overload program was undertaken three times per week with subjects performing four sets of six to eight repetitions at 80% of their one repetition maximum (IRM). Maximum voluntary contraction (MVC) and contractile properties were measured at 0, 12, and 24 weeks in the exercise group and at 0 and 24 weeks in the controls. The IRM was used to assess dynamic strength at 0 and 24 weeks in the exercise group. Contractile measures consisted of supramaximal isometric twitch and post-activation twitch parameters. Muscle size was estimated from anthropometric measurements. Compared with the control group, the exercise group MVC increased by about 20% and time to peak tension was slowed by about 11%. Also in the exercise group the peak rate of torque development of the potentiated twitch was reduced by about 10%. Twitch potentiation was substantial in both groups (about 140%) and unaffected by training. The 1 RM increased by about 30%, and there was a non-singificant positive change of 8.6% in the muscle plus bone cross-sectional area in the exercise group. The results show that the force generating capacity of the triceps brachii in these men can be significantly improved for up to 24 weeks using concentric overload training. Furthermore, the finding of slowed twitch properties and no change in peak twitch amplitude substantiate and extend the limited data currently available on intrinsic contractile changes in the elderly. Mechanisms responsible for slowed twitch properties and their functional significance following strength training in aged men remain uncertain.