Effects of aerobic fitness on hypohydration‐induced physiological strain and exercise impairment

Merry, Troy L.; Ainslie, Philip N.; Cotter, James D.

doi:10.1111/j.1748-1716.2009.02051.x

Cited by 66 publications

(56 citation statements)

References 49 publications

(92 reference statements)

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“…Mild hypohydration exacerbates cardiovascular and thermoregulatory strain and tends to impair endurance performance, but greater aerobic fitness attenuates these physiological effects. However, in a study by Merry et al [28], performance power was reduced by 13% in untrained subjects and by 7% in trained subjects without an effect of fitness (p = 0.38). The effects of hyperthermia on VO 2 max and physical performance in men and women are almost identical [29].…”

Section: Discussionmentioning

confidence: 94%

Deep mineral water accelerates recovery after dehydrating aerobic exercise: a randomized, double-blind, placebo-controlled crossover study

Stasiule

Čapkauskienė

Vizbaraitė

et al. 2014

Journal of the International Society of Sports Nutrition

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BackgroundThe effect of deep mineral water (DMW) with moderate mineralization on the recovery of physical performance after prolonged dehydrating aerobic exercise in the heat was studied in nine healthy, physically active (VO2max = 45.8 ± 8.4 mL kg−1 min−1) women aged 24.0 ± 3.7 years.MethodsWe conducted a randomized, double-blind, placebo-controlled crossover human study to evaluate the effect of ingestion of natural mineral water extracted from a depth of 689 m on recovery from prolonged fatiguing aerobic running conducted at 30°C.ResultsMean body weight decreased by 2.6–2.8% following dehydrating exercise. VO2max was 9% higher after 4 h of recovery after rehydrating with DMW compared with plain water. Leg muscle power recovered better during the slow phase of recovery and was significantly higher after 48 h of recovery after rehydrating with DMW compared with plain water.ConclusionsDMW with moderate mineralization was more effective in inducing recovery of aerobic capacity and leg muscle power compared with plain water following prolonged dehydrating aerobic running exercise.

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Section: Discussionmentioning

confidence: 94%

Deep mineral water accelerates recovery after dehydrating aerobic exercise: a randomized, double-blind, placebo-controlled crossover study

Stasiule

Čapkauskienė

Vizbaraitė

et al. 2014

Journal of the International Society of Sports Nutrition

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“…The data from the short-term phase are somewhat at odds with recent work indicating that dehydrating during 90 min daily exercise-heat stress within a 5-day isothermal HA programme facilitated some aspects of HA (Garrett et al, 2014), but the reason for these discrepant findings is unclear. Aerobic fitness reduces the strain induced by mild hypohydration (Merry et al, 2010) and aerobically fit individuals require a greater stimulus to challenge the fluid-regulatory processes than less fit individuals (Merry et al, 2008). However, the fitness of our participants [VO 2max 57(7) mL·kg −1 ·min −1 ; PPO 338(49) W)] was comparable to Garrett et al (2014) [VO 2max 60(7) mL·kg −1 ·min −1 ; PPO 340(30) W] and greater hypohydration lacks ecological validity, could impair some training adaptations (Judelson et al, 2008) and in rodents at least, might impair aspects of the genomic (Schwimmer et al, 2006) and phenotypic (Horowitz et al, 1999) adaptation to heat.…”

Section: Discussionmentioning

confidence: 99%

Effect of Permissive Dehydration on Induction and Decay of Heat Acclimation, and Temperate Exercise Performance

et al. 2016

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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.

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“…The strain of the physiological mechanisms during exercise is influenced by many factors such as morphological including body mass (Anderson, 1999; Cheung et al, 2000; Havenith et al, 1998; Havenith, 2001) and body composition (Jay and Kenney, 2007), age (Moran et al, 2002; Pandolf, 1997), gender (Moran et al, 1999), body hydration (Merry et al, 2010; Moran et al, 1998b; Maughan and Shireffs, 2010), aerobic capacity (Merry et al, 2010; Mora-Rodrigez et al, 2010; Tikuisis et al, 2002), heat acclimation (Aoyagi et al, 1997; Kondo et al, 2009; Nadel et al, 1974; Periard et al, 2015), a type of exercise, environmental conditions and protective clothing (Borg et al, 2015; Epstein and Moran, 2006; Gonzalez-Alonso, 2012; Pilch et al, 2014; Pokora et al, 2014). …”

Section: Introductionmentioning

confidence: 99%

Application of A Physiological Strain Index in Evaluating Responses to Exercise Stress – A Comparison Between Endurance and High Intensity Intermittent Trained Athletes

Pokora

Żebrowska

2016

Journal of Human Kinetics

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The study evaluated differences in response to exercise stress between endurance and high-intensity intermittent trained athletes in a thermoneutral environment using a physiological strain index (PSI). Thirty-two subjects participated in a running exercise under normal (23°C, 50% RH) conditions. The group included nine endurance trained athletes (middle-distance runners - MD), twelve high-intensity intermittent trained athletes (soccer players - HIIT) and eleven students who constituted a control group. The exercise started at a speed of 4 km·h–1 which was increased every 3 min by 2 km·h–1 to volitional exhaustion. The heart rate was recorded with a heart rate monitor and aural canal temperature was measured using an aural canal temperature probe. The physiological strain index (PSI) and the contribution of the circulatory and thermal components to the overall physiological strain were calculated from the heart rate and aural canal temperature. The physiological strain index differed between the study and control participants, but not between the MD and HIIT groups. The physiological strain in response to exercise stress in a thermoneutral environment was mainly determined based on the circulatory strain (MD group - 73%, HIIT group – 70%). The contribution of the circulatory and thermal components to the physiological strain did not differ significantly between the trained groups (MD and HIIT) despite important differences in morphological characteristics and training-induced systemic cardiovascular and thermoregulatory adaptations.

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Effects of aerobic fitness on hypohydration‐induced physiological strain and exercise impairment

Abstract: Mild hypohydration exacerbated cardiovascular and thermoregulatory strain and tended to impair endurance performance, but aerobic fitness attenuated the physiological effects.

Cited by 66 publications

References 49 publications

Deep mineral water accelerates recovery after dehydrating aerobic exercise: a randomized, double-blind, placebo-controlled crossover study

Deep mineral water accelerates recovery after dehydrating aerobic exercise: a randomized, double-blind, placebo-controlled crossover study

Effect of Permissive Dehydration on Induction and Decay of Heat Acclimation, and Temperate Exercise Performance

Application of A Physiological Strain Index in Evaluating Responses to Exercise Stress – A Comparison Between Endurance and High Intensity Intermittent Trained Athletes

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