# Hand and forearm immersion in hot water at half-time enhances subsequent leg muscle strength

## TL;DR

Immersing hands and forearms in hot water during a break improves leg muscle strength and body temperature in cold conditions.

## Contribution

Hot-water immersion of hands and forearms during half-time improves knee extensor muscle strength in cold environments.

## Key findings

- MVC force after hot-water immersion was significantly higher than after seated rest.
- Rectal temperature was significantly higher following hot-water immersion compared to seated rest.
- Cycling sprint peak power output did not differ significantly between the two interventions.

## Abstract

We aimed to investigate the effects of hot-water immersion of the hand and
forearm during half-time (HT) on the physiological responses, leg muscle
strength, and cycling sprint performance in the cold. Ten recreationally active
men performed the experimental trials that consisted of 40 min intermittent
cycling, followed by a 15-min HT, and then an intermittent cycling sprint test
in a cold (5°C and 50% relative humidity). During HT, the participants underwent
two different interventions: seated rest (CON) or hand and forearm heating
(HEAT). The intermittent cycling sprint test comprised 10 sets of 5 s of maximal
pedaling and 25 s of recovery. In addition, the participants performed maximal
voluntary contraction (MVC) in knee extension before and after HT. Although the
peak power output in the intermittent cycling sprint test did not significantly
differ between trials (p>0.05), the rectal temperature (T
re
)
following HT in HEAT was significantly higher than in CON (p=0.026). In
addition, the MVC force after HT was significantly higher in HEAT than in CON
(p<0.001). This suggests hot-water immersion of hand and forearm during HT
improves knee extensor muscle strength and attenuates the T
re
decrease in a cold environment.