Peak power output and the velocity at which peak power occurs (V_opt) during sprint cycling has been shown to be lower in older people (Davies et al. 1983). The lower power output can be explained in part by reduced muscle mass; however, this should not explain the lower V_opt. It was the aim of the present study to determine if the lower V_opt in older people is related to a lower proportion of fast myosin isoforms in their quadriceps muscle.

We examined the powerÐvelocity characteristics of 14 healthy men (7 young, 29 ± 2 years; 7 old, 74 ± 2 years) using a recently developed inertial cycle system (Pearson et al. 2002). Prior to testing, a standardised 5 min warm-up was undertaken, two maximal sprints were then performed at five inertial loads, ranging from 0.16 to 0.54 kg m². The best performance was used for analysis. V_opt was determined by a third-order polynomial fitting technique. Following local anaesthesia (1 % Lignocaine), muscle biopsy samples were obtained from the vastus lateralis muscle using the needle technique and were subsequently analysed for relative MHC isoform composition using gel electrophoresis (SDS-PAGE).

The mean (± S.E.M.) peak power, V_opt and % MHC-II (MHC-IIA + MHC-IIX) were 847 ± 47 vs. 406 ± 53 Watts, 120 ± 4 vs. 89 ± 6 r.p.m. and 52 ± 7 vs. 25 ± 7 % for the young and older groups, respectively. All measures were shown to be significantly lower in the elderly group when compared with the young (P < 0.05, Student’s unpaired t test). V_opt was found to correlate significantly with the % MHC-II (Fig. 1).

The results show that the lower V_opt in older men relates closely to a lower proportion of the fast contracting MHC-II isoforms in their quadriceps muscle.

S.D.R.H. is a Wellcome Trust Research Fellow.

All procedures accord with current local guidelines and the Declaration of Helsinki.