Effect of Permissive Dehydration on Induction and Decay of Heat Acclimation, and Temperate Exercise Performance.
Authors: Neal, R.A., Massey, H.C., Tipton, M.J., Young, J.S., Corbett, J.
Journal: Front Physiol
Publication Date: 2016
Volume: 7
Pages: 564
ISSN: 1664-042X
DOI: 10.3389/fphys.2016.00564
Abstract:Purpose: It has been suggested that dehydration is an independent stimulus for heat acclimation (HA), possibly through influencing fluid-regulation mechanisms and increasing plasma volume (PV) expansion. There is also some evidence that HA may be ergogenic in temperate conditions and that this may be linked to PV expansion. We investigated: (i) the influence of dehydration on the time-course of acquisition and decay of HA; (ii) whether dehydration augmented any ergogenic benefits in temperate conditions, particularly those related to PV expansion. Methods: Eight males [VO2max: 56.9(7.2) mL·kg-1·min-1] undertook two HA programmes (balanced cross-over design), once drinking to maintain euhydration (HAEu) and once with restricted fluid-intake (HADe). Days 1, 6, 11, and 18 were 60 min exercise-heat stress tests [HST (40°C; 50% RH)], days 2-5 and 7-10 were 90 min, isothermal-strain (Tre ~ 38.5°C), exercise-heat sessions. Performance parameters [VO2max, lactate threshold, efficiency, peak power output (PPO)] were determined pre and post HA by graded exercise test (22°C; 55%RH). Results: During isothermal-strain sessions hypohydration was achieved in HADe and euhydration maintained in HAEu [average body mass loss -2.71(0.82)% vs. -0.56(0.73)%, P < 0.001], but aldosterone concentration, power output, and cardiovascular strain were unaffected by dehydration. HA was evident on day 6 {reduced end-exercise Tre [-0.30(0.27)°C] and exercise heart rate [-12(15) beats.min-1], increased PV [+7.2(6.4)%] and sweat-loss [+0.25(0.22) L.h-1], P < 0.05} with some further adaptations on day 11 {further reduced end-exercise Tre [-0.25(0.19)°C] and exercise heart rate [-3(9) beats.min-1], P < 0.05}. These adaptations were not notably affected by dehydration and were generally maintained 7-days post HA. Performance parameters were unchanged, apart from increased PPO (+16(20) W, irrespective of condition). Conclusions: When thermal-strain is matched, permissive dehydration which induces a mild, transient, hypohydration does not affect the acquisition and decay of HA, or endurance performance parameters. Irrespective of hydration, trained individuals require >5 days to optimize HA.
https://eprints.bournemouth.ac.uk/29701/
Source: PubMed
Effect of Permissive Dehydration on Induction and Decay of Heat Acclimation, and Temperate Exercise Performance
Authors: Neal, R.A., Massey, H.C., Tipton, M.J., Young, J.S., Corbett, J.
Journal: FRONTIERS IN PHYSIOLOGY
Publication Date: 23/11/2016
Volume: 7
ISSN: 1664-042X
DOI: 10.3389/fphys.2016.00564
https://eprints.bournemouth.ac.uk/29701/
Source: Web of Science
Effect of permissive dehydration on induction and decay of heat acclimation, and temperate exercise performance
Authors: Rendell, R., Massey, H., Tipton, M., Young, J., Corbett, J.
Journal: Frontiers in Physiology
Publication Date: 23/11/2016
Publisher: Frontiers Media
ISSN: 1664-042X
https://eprints.bournemouth.ac.uk/29701/
Source: Manual
Effect of Permissive Dehydration on Induction and Decay of Heat Acclimation, and Temperate Exercise Performance.
Authors: Neal, R.A., Massey, H.C., Tipton, M.J., Young, J.S., Corbett, J.
Journal: Frontiers in physiology
Publication Date: 01/2016
Volume: 7
Pages: 564
eISSN: 1664-042X
ISSN: 1664-042X
DOI: 10.3389/fphys.2016.00564
Abstract:Purpose: It has been suggested that dehydration is an independent stimulus for heat acclimation (HA), possibly through influencing fluid-regulation mechanisms and increasing plasma volume (PV) expansion. There is also some evidence that HA may be ergogenic in temperate conditions and that this may be linked to PV expansion. We investigated: (i) the influence of dehydration on the time-course of acquisition and decay of HA; (ii) whether dehydration augmented any ergogenic benefits in temperate conditions, particularly those related to PV expansion. Methods: Eight males [VO2max: 56.9(7.2) mL·kg-1·min-1] undertook two HA programmes (balanced cross-over design), once drinking to maintain euhydration (HAEu) and once with restricted fluid-intake (HADe). Days 1, 6, 11, and 18 were 60 min exercise-heat stress tests [HST (40°C; 50% RH)], days 2-5 and 7-10 were 90 min, isothermal-strain (Tre ~ 38.5°C), exercise-heat sessions. Performance parameters [VO2max, lactate threshold, efficiency, peak power output (PPO)] were determined pre and post HA by graded exercise test (22°C; 55%RH). Results: During isothermal-strain sessions hypohydration was achieved in HADe and euhydration maintained in HAEu [average body mass loss -2.71(0.82)% vs. -0.56(0.73)%, P < 0.001], but aldosterone concentration, power output, and cardiovascular strain were unaffected by dehydration. HA was evident on day 6 {reduced end-exercise Tre [-0.30(0.27)°C] and exercise heart rate [-12(15) beats.min-1], increased PV [+7.2(6.4)%] and sweat-loss [+0.25(0.22) L.h-1], P < 0.05} with some further adaptations on day 11 {further reduced end-exercise Tre [-0.25(0.19)°C] and exercise heart rate [-3(9) beats.min-1], P < 0.05}. These adaptations were not notably affected by dehydration and were generally maintained 7-days post HA. Performance parameters were unchanged, apart from increased PPO (+16(20) W, irrespective of condition). Conclusions: When thermal-strain is matched, permissive dehydration which induces a mild, transient, hypohydration does not affect the acquisition and decay of HA, or endurance performance parameters. Irrespective of hydration, trained individuals require >5 days to optimize HA.
https://eprints.bournemouth.ac.uk/29701/
Source: Europe PubMed Central