ORIGINAL ARTICLE   

Gazzetta Medica Italiana Archivio per le Scienze Mediche 2018 June;177(6):284-92

DOI: 10.23736/S0393-3660.17.03578-1

Copyright © 2017 EDIZIONI MINERVA MEDICA

language: English

The impact of water temperature on fatigue and cardiovascular responses during exhaustive aquatic exercise

Ioanna G. KITTA, Helen N. SOULTANAKIS ✉

School of Physical Education and Sports Science, National and Kapodistrian University of Athens, Athens, Greece

BACKGROUND: Hot environmental conditions in conjunction with increased humidity, decreased wind speed, dehydration, high intensity exercise, and body fat, can lead to thermal stress and consequently to fatigue and reduced performance. What is surprising, in the area of aquatic thermoregulation is the fact that the heat induced cardiovascular strain has been lately observed to occur at much lower temperatures in water in humans. The purpose of this study was to investigate whether an incremental deep water running (DWR) test to exhaustion, in 31 °C, would accelerate fatigue and cardiovascular responses, when compared to a cooler temperature of 24 °C.
METHODS: Nine healthy male athletes (22.2±3.1 years; 72.9±5.3 kg; 178±5.1 cm; 7±1.7% fat) participated in this study. A progressive, deep water running test to exhaustion took place at two different temperatures, at 31 °C and 24 °C. The exercise load increased in 3-minute stages, either by increasing the stride frequency or adding weight on the participants, or both, in a cross-over design.
RESULTS: The length of time to exhaustion was significantly lower in warm versus cool water (16.61±1.51 vs. 19.16±1.83 min), and peak-HR occurred at an earlier 3-min stage, in warm water (5.77±0.46 vs. 6.55±0.62 stage). Systolic and mean arterial pressure, increased significantly only after DWR in warm water (P<0.05). RPE changed similarly between temperatures and did not reflect the accelerated fatigue noticed in warm water. Blood lactate showed similar trends with similar rises post exercise (9.31±1.34 in cold vs. 10.87±0.95 mmol/L in hot water), and blood glucose did not change.
CONCLUSIONS: A water temperature of 31 °C generally perceived to be thermoneutral in the water, leads to cardiovascular strain and a reduction in performance during exercise. The underlying mechanisms causing an acceleration of fatigue and an ANS mediated cardiovascular strain in response to DWR in 31 °C water, integrate many physiological systems. The determining factor appears to be the limited ability of man to dissipate heat via evaporation in response to exercise in the water.

KEY WORDS: Water - Exercise - Cardiovascular system