Introduction

Advancing age is typically associated with a decline in muscle strength and power (1).  However, for many individuals getting older this is also accompanied by insufficient levels of physical activity which can also contribute to a decline in function. The present study thus compared a number of measures of muscle function in older males and females who were either i) regular exercisers (recreational road cyclists) or ii) healthy non-exercisers.  

Methods

A total of 120 healthy, older individuals aged 64-86 years were recruited. Seventy of those were amateur road cyclists (44M: M-C; 72±6 years; height 1.74±0.06m; weight 74.2±9.6kg, 26F: F-C 71±6 years; height 1.62±0.05m; weight 58.8±6.1kg). Fifty healthy, but non-exercising participants were also studied (22M: M-ONE (71±5 years; height 1.75±0.07m; weight 80.6±8.5kg, 28F: F-ONE 71±6 years; height 1.60±0.06m).Each participant underwent testing of i) maximum voluntary isometric knee extensor strength (MVIKES) with twitch interpolation to determine levels of voluntary activation; ii) maximal explosive cycle power and iii) handgrip strength. DXA scanning determined lower limb fat free mass (LLFFM) and an incremental exercise test was used to determine aerobic power (VO_2peak). The data (mean±SD) were analysed using a two-factor ANOVA.

Results

The difference in exercise status between the cyclists and non-exercisers was confirmed by the lower VO_2peak in the non-exercisers (35.7±7.5 vs 22.5±6.0 ml.kg^-1.min^-1; p<0.001).  MVIKES showed a significant effect of exercise (cyclists stronger; p<0.001) and sex (males stronger, p<0.001) (M-C 164.8±36.0; M-ONE 146.5±39.2; F-C 114.3±19.0 and F-ONE 101.2±26.3 Nm). When normalised to LLFFM there was no difference between males and females, but the cyclists were still stronger (p<0.05) compared to the non-exercisers (M-C 8.9±2.2; M-ONE 8.3±2.1; F-C 10.0±4.6; F-ONE 7.4±2.0 Nm.kg.LLFFM^-1). This may partly be explained by higher levels of voluntary activation (p<0.001) in the cyclists and in this measure the females exhibited higher levels (p<0.05) than the males (M-C 88.3±6.1; M-ONE 79.6±14.1; F-C 89.5±6.4; F-ONE 85.8±12.1 %). Explosive power during sprint cycling was greater in cyclists compared to non-exercisers and in males compared to females (M-C 1004.1±176.8; M-ONE 874.5±241.7; F-C 740.6±114.1 and F-ONE 617.0±133.5 W). The difference in power between the sexes was removed when normalised to LLFFM but the cyclists could generate more normalised peak power (p<0.001) compared to the non-exercisers (M-C 56.0±9.0; M-ONE 49.5±12.2; F-C 63.3±21.6 and F-ONE 52.2±11.7 W.kg.FFM^-1). Handgrip strength was greater in the cyclists (p<0.001) compared to non-exercisers and the males stronger (p<0.001) than females (M-C 415.9±85.6; M-ONE 371.3±72.7; F-C 276.7±93.2 and F-ONE 198.9±49.1 N). These differences remained when data were normalised to total FFM (M-C 7.7±1.6; M-ONE 6.8±1.2; F-C 7.1±2.5 and F-ONE 5.2±1.2 N.kg^-1).

 

Conclusion

The results show superior levels of neuromuscular function in older cyclists compared to non-exercisers and older males compared to females. The differences between males and females in lower limb strength and power could be accounted for by a smaller LLFFM mass in females. However, normalisation to LLFFM did not reduce the differences between cyclists and non-exercisers. This suggests that exercise during old age results in more optimal neuromuscular function compared with not undertaking exercise.