Heat Exposure and Hypohydration Exacerbate Physiological Strain During Load Carrying
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Elizabeth L. Adams [1] ; Douglas J. Casa ; Robert A. Huggins ; Julie K. DeMartini ; Rebecca L. Stearns ; Rachel M. Kennedy [2] ; Megan M. Bosworth [3] ; Lindsay J. DiStefano ; Lawrence E. Armstrong ; Carl M. Maresh
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[1] University of Connecticut
University of Connecticut
Town of Mansfield, Estados Unidos
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[2] Lehigh University
Lehigh University
City of Bethlehem, Estados Unidos
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[3] University of Hartford
University of Hartford
Town of West Hartford, Estados Unidos
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- Localización: Journal of strength and conditioning research: the research journal of the NSCA, ISSN 1064-8011, Vol. 33, Nº. 3, 2019, págs. 727-735
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
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Resumen
Heat exposure and hypohydration induce physiological and psychological strain during exercise; however, it is unknown if the separate effects of heat exposure and hypohydration are synergistic when co-occurring during loaded exercise. This study compared separate and combined effects of heat exposure and hypohydration on physiological strain, mood state, and visual vigilance during loaded exercise. Twelve men (mean +/- SD; age, 20 +/- 2 years; body mass, 74.0 +/- 8.2 kg; maximal oxygen uptake, 57.0 +/- 6.0 ml[middle dot]kg-1[middle dot]min-1) completed 4 trials under the following conditions: euhydrated temperate (EUT), hypohydrated temperate (HYT), euhydrated hot (EUH), and hypohydrated hot (HYH). Exercise was 90 minutes of treadmill walking (~50% V[Combining Dot Above]O2max, 5% grade) while carrying a 45-lb rucksack. Profile of Mood States and the Scanning Visual Vigilance Test were completed before and after exercise. The separate effects of heat exposure (EUH) and hypohydration (HYT) on post-exercise rectal temperature (Tre) were similar (38.25 +/- 0.63[degrees]C vs. 38.22 +/- 0.29[degrees]C, respectively, p > 0.05), whereas in combination (HYH), post-exercise Tre was far greater (39.32 +/- 0.43[degrees]C). Increase in Tre per 1% body mass loss (BML) for HYH (vs. EUH) was greater than HYT (vs. EUT) (0.32 vs. 0.04[degrees]C, respectively, p = 0.02); heart rate increase per 1% BML for HYH (vs. EUH) was 7 b[middle dot]min-1 compared with HYT (vs. EUT) at 3 b[middle dot]min-1 (p = 0.30). Hypohydrated hot induced greater mood disturbance (post-exercise - pre-exercise) (35 +/- 21 units) compared with other conditions (EUT = 3 +/- 9 units; HYT = 3 +/- 16 units; EUH = 16 +/- 26 units; p < 0.001). No differences occurred in visual vigilance (p > 0.05). Independently, heat exposure and hypohydration induced similar physiological strain during loaded exercise; when combined, heat exposure with hypohydration, synergistically exacerbated physiological strain and mood disturbance.
