Exercise heat acclimation and post-exercise hot water immersion improve resting and exercise responses to heat stress in the elderly.

OBJECTIVES

To investigate the efficacy of heat acclimation (HA) in the young (Y) and elderly (E) following exercise-HA, and the elderly utilising post-exercise hot water immersion HA (E).

DESIGN

Cross-sectional study.

METHOD

Twenty-six participants (Y: n = 11 aged 22 ± 2 years, En = 8 aged 68 ± 3 years, E: n = 7 aged 73 ± 3 years) completed two pre-/post-tests, separated by five intervention days. Y and E exercised in hot conditions to raise rectal temperature (T) ≥38.5 °C within 60 min, with this increase maintained for a further 60 min. E completed 30 min of cycling in temperate conditions, then 30 min of HWI (40 °C), followed by 30 min seated blanket wrap. Pre- and post-testing comprised 30 min rest, followed by 30 min of cycling exercise (3.5 W·kg Ḣ and a six-minute walk test (6MWT), all in 35 °C, 50% RH.

RESULTS

The HA protocols did not elicit different mean heart rate (HR), T, and duration T ≥ 38.5 °C (p > 0.05) between Y, E, and E groups. Resting T, peak skin temperature, systolic and mean arterial pressure, perceived exertion and thermal sensation decreased, and 6MWT distance increased pre- to post-HA (p < 0.05), with no difference between groups. Y also demonstrated a reduction in resting HR (p < 0.05). No change was observed in peak T or HR, vascular conductance, sweat rate, or thermal comfort in any group (p > 0.05).

CONCLUSIONS

Irrespective of age or intervention, HA induced thermoregulatory, perceptual and exercise performance improvements. Both exercise-HA (E), and post-exercise HWI (E) are considered viable interventions to prepare the elderly for heat stress.