Abstract
Purpose: Warfighters must be able to move and react quickly
to ever changing threats and hostile situations in all types of
environments. In cold environments, deterioration of physical performance
occurs due to reduced muscle contractility and efficiency
resulting from cold muscles. Shivering thermogenesis also fatigues
muscles and uses valuable energy stores, further limiting physical
performance. Cold acclimation, however, improves insulation
and reduces shivering, leading to greater heat retention while
minimizing energy expenditure. Therefore, it is possible that cold
acclimation could improve physical performance by keeping muscles
warmer and energetically ready to perform. The purpose of
this study is to determine the impact that cold acclimation has on
physical performance.
Methods: Twelve healthy subjects (age: 25.6 ± 5.2 y, height:
174.0 ± 8.9 cm, weight: 75.6 ± 13.1 kg) first performed a 20-minute
baseline cycling test in 22 ◦C, 40% humidity without prior cold
exposure. Twenty-four hours later they began a 7-day cold acclimation
protocol, consisting of 90-minute, once daily, cold water
immersions (10 ◦C, immersed to mid-sternum). Following each
immersion, subjects exited the water, dried off, and remained
seated for 60 minutes. On days one, four, and seven of the cold acclimation
protocol, subjects completed the same 20-minute cycling
test in 22 ◦C, 40% humidity, after sitting for 60 minutes following
the immersion. Measurements of mechanical work completed, core
and skin temperatures, heart rate, skin blood flow, perceived exertion,
and thermal sensation were measured during each cycling
test.
Results: Subjects experienced a reduction in shivering and an
enhanced vasoconstriction response, supporting a successful acclimation
to cold. Although perceived exertion was similar between
all four cycling tests, the amount of mechanical work produced during
the baseline cycling test (220 ± 70 kJ) was greater (p < 0.001)
than all three cycling tests that were performed following immersions
(195 ± 58, 197 ± 60, and 194 ± 62 kJ), suggesting that cold
exposure deteriorated cycling performance. However, this impairment
was not attenuated over the cold acclimation period.
Conclusions: Findings from this study show that cycling performance
is impaired following cold water immersion. Results
also suggest that a 7-day cold acclimation protocol does not
improve cycling performance. Therefore, warfighters and military
commands looking to enhance physical performance in cold
environments should seek other techniques to attenuate physical
performance impairments that are observed following severe cold
stress.
Original language | English |
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Article number | 126 |
Pages (from-to) | S74-S74 |
Number of pages | 1 |
Journal | Journal of Science and Medicine in Sport |
Volume | 20 |
Issue number | suppl 2 |
Publication status | Published - Nov 2017 |
Event | 4th Internaitonal Soldiers' Congress on Physical Performance - Melbourne, Australia Duration: 28 Nov 2017 → 1 Dec 2017 |