Comparison of power and EMG during 6-s all-out cycling between young and older women

Abstract

To investigate the effects of ageing on the neural control strategies governing sprint cycling on a friction-loaded cycle-ergometer, 10 older (aged 70–83yr) and 8 young (aged 19–35yr) healthy women completed seven 6-s all-out cycling trials against varying loads. Root mean square (RMS), median frequency and muscle fibre conduction velocity were determined from the vastus lateralis of the dominant limb during each pedal stroke. Peak power was 43% lower in the older group compared to the younger (p < 0.001) and was accompanied by a significantly lower RMS (p < 0.05). No differences were observed in the other electromyography (EMG) parameters between the groups (p > 0.05). ΔRMS from the first to the sixth second during each trial was found to increase significantly with the development of power output in both groups (p < 0.05). For the first time during an all-out 6-s cycle trial, it has been demonstrated that older women's lower mechanical power output was accompanied by a significantly lower RMS, which indicates a decline in either the number of active of motor units or a reduced discharge rate. Hence, changes in motor units can be regarded as a contributory factor to the decline of muscle power with advancing age. Overall, though, similar neural strategies are adopted in both younger and older populations.

Keywords:

• Muscle power
• ageing
• torque-velocity relationship
• surface electromyography
• conduction velocity
• vastus lateralis

Acknowledgements

The study was financially supported by the Royal Society of Edinburgh/Lloyds TSB Foundation for Scotland.