Motor performance is preserved in healthy aged adults following severe whole-body hyperthermia

Abstract

Healthy aging is associated with a progressive decline in motor performance and thermoregulatory efficiency. Functional consequences of severe whole-body hyperthermia on neurophysiological functions in healthy aged men have not been investigated. To determine whether severe whole-body hyperthermia (increase in rectal temperature of about 2.5 °C) induced by lower-body heating in older men (64–80 years, n = 9) would suppress excitability of reflexes, voluntarily and electrically induced ankle plantar flexor contractile properties were compared with those in young men (19–21 years, n = 11). Though no aging effect on hyperthermia-induced reflex amplitudes was observed, a decrease in maximal H-reflex and V-wave latencies was found to be greater in older than in young men. In older men, lower-body heating was accompanied by a significant increase in twitch and tetani test torque in parallel with a greater decrease in muscle contraction time. There was no temperature-depended aging effect on the voluntary activation and maximal voluntary torque production. Despite delayed and weakened thermoregulation and age-related decline in neuromuscular function, motor performance in whole-body severe hyperthermia is apparently preserved in healthy aging.

Keywords:

• Heat stress
• reflexes
• aging muscle
• electromyography (EMG)

Acknowledgements

The authors are grateful to the study participants.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Research Council of Lithuania (Grant No. S-MIP-17–29).