Low and moderate exercise intensity produced similar rewarming after cold-water immersion in soldiers

A randomized matched-pairs trial tested whether exercise intensity after outdoor cold-water immersion affected how quickly 28 military personnel rewarmed. Core, hand, and foot temperatures recovered at comparable rates regardless of whether participants exercised at a low or moderate effort level.

What the study found

The two exercise intensities produced essentially equivalent rewarming outcomes — a null finding that is itself informative. After 10 minutes of immersion in near-freezing outdoor water, participants were assigned to either a lower-effort or a moderately higher-effort exercise protocol lasting 40 minutes, and neither group warmed the core, hands, or feet meaningfully faster than the other.

Heart rate was measurably higher in the moderate-intensity group after 20 minutes of exercise, confirming that the two protocols did differ physiologically — yet that cardiovascular difference did not translate into a detectable difference in tissue temperature recovery across any of the body sites measured.

Importantly, the moderate-intensity protocol did not worsen the afterdrop effect — the continued decline in core temperature that can occur even after a person leaves cold water. This was a specific safety-relevant question the researchers set out to answer, and the data offered reassurance on that point.

The authors suggest that individuals recovering from cold-water immersion may be able to choose whichever exercise effort level feels manageable or suits their circumstances, without sacrificing rewarming speed — though they frame this conclusion cautiously given the study's scope.

Limits worth knowing

The sample was small (28 participants, 27 of them male) and drawn exclusively from military personnel, limiting how broadly the results apply. The immersion and rewarming took place in a specific outdoor environment at a fixed water and air temperature, so different environmental conditions could yield different results. The study measured only 40 minutes of rewarming; longer recovery windows were not assessed. No funding disclosures were identified in the available information. Individual factors such as body composition, fitness level, and cold acclimatization varied among participants and could have influenced outcomes in ways the design could not fully control.

About this entry. The Heartwood Review summarizes published, peer-reviewed research in its own words and links to the original source. It is not medical advice; consult a physician before beginning or changing any thermal or recovery practice. Findings summarized here describe the study cited, not any product sold by Teak & Marble Atelier. Corrections.