Human skeletal sarcoplasmic reticulum Ca21 uptake and muscle function with aging and strength training

Hunter, Sandra K., Martin W. Thompson, Patricia A. Ruell, Alison R. Harmer, Jeanette M. Thom, Tom H. Gwinn, and Roger D. Adams. Human skeletal sarcoplasmic reticulum Ca21 uptake and muscle function with aging and strength training. J. Appl. Physiol. 86(6): 1858–1865, 1999.—This study investigated the adaptations of skeletal muscle sarcoplasmic reticulum (SR) Ca21 uptake, relaxation, and fiber types in young (YW) and elderly women (EW) to high-resistance training. Seventeen YW (18–32 yr) and 11 EW (64–79 yr) were assessed for 1) electrically evoked relaxation time and rate of the quadriceps femoris; and 2) maximal rates of SR Ca21 uptake and Ca21-ATPase activity and relative fiber-type areas, analyzed from muscle biopsies of the vastus lateralis. EW had significantly slower relaxation rates and times, decreased SR Ca21 uptake and Ca21-ATPase activity, and a larger relative type I fiber area than did YW. A subgroup of 9 young (YWT) and 10 elderly women (EWT) performed 12 wk of high-resistance training (8 repetition maximum) of the quadriceps and underwent identical testing procedures preand posttraining. EWT significantly increased their SR Ca21 uptake and Ca21-ATPase activity in response to training but showed no alterations in speed of relaxation or relative fiber-type areas. In YWT none of the variables was altered after resistance training. These findings suggest that 1) a reduced SR Ca21 uptake in skeletal muscle of elderly women was partially reversed with resistance training and 2) SR Ca21 uptake in the vastus lateralis was not the rate-limiting mechanism for the slowing of relaxation measured from electrically evoked quadriceps muscle of elderly women.