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1.
Artigo em Inglês | MEDLINE | ID: mdl-32497436

RESUMO

This proof-of-concept study used a web application to predict runner sweat losses using only energy expenditure and air temperature. A field study (FS) of n = 37 runners was completed with n = 40 sweat loss observations measured over one hour (sweat rate, SR). Predictions were also compared to 10 open literature (OL) studies where individual runner SR was reported (n = 82; 109 observations). Three prediction accuracy metrics were used; for FS, the mean absolute error (MAE) and concordance correlation coefficient (CCC) were calculated to include a 95% confidence interval [CI]; for OL, the percentage concordance (PC) was examined against calculation of accumulated under- and overdrinking potential. The MAE for FS runners was 0.141 kg [0.105, 0.177], which was less than estimated scale weighing error on 85% of occasions. The CCC was 0.88 [0.82, 0.93]. The PC for OL was 96% for avoidance of both under- and overdrinking and 93% overall. All accuracy metrics and their CI's were below acceptable error tolerance. Input errors of ±10% and ± 1°C for energy expenditure and air temperature dropped the PC to between 84 and 90%. This study demonstrates the feasibility of accurately predicting SR from energy expenditure and air temperature alone. NOVELTY • Results demonstrate that accurate runner SR prediction is possible with knowledge of only energy expenditure and air temperature. • SR prediction error was smaller than body weighing error in 85% of observations. • Accurate runner SR prediction could help mitigate the common risks of over- and under-drinking.

2.
Nutrients ; 12(5)2020 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-32365848

RESUMO

We investigated the impact of nutrient intake on hydration biomarkers in cyclists before and after a 161 km ride, including one hour after a 650 mL water bolus consumed post-ride. To control for multicollinearity, we chose a clustering-based, machine learning statistical approach. Five hydration biomarkers (urine color, urine specific gravity, plasma osmolality, plasma copeptin, and body mass change) were configured as raw- and percent change. Linear regressions were used to test for associations between hydration markers and eight predictor terms derived from 19 nutrients merged into a reduced-dimensionality dataset through serial k-means clustering. Most predictor groups showed significant association with at least one hydration biomarker: 1) Glycemic Load + Carbohydrates + Sodium, 2) Protein + Fat + Zinc, 3) Magnesium + Calcium, 4) Pinitol, 5) Caffeine, 6) Fiber + Betaine, and 7) Water; potassium + three polyols, and mannitol + sorbitol showed no significant associations with any hydration biomarker. All five hydration biomarkers were associated with at least one nutrient predictor in at least one configuration. We conclude that in a real-life scenario, some nutrients may serve as mediators of body water, and urine-specific hydration biomarkers may be more responsive to nutrient intake than measures derived from plasma or body mass.

3.
Sports Med ; 50(3): 449-459, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32020542

RESUMO

The primary means of disseminating sport and exercise science research is currently through journal articles. However, not all studies, especially those with null findings, make it to formal publication. This publication bias towards positive findings may contribute to questionable research practices. Preregistration is a solution to prevent the publication of distorted evidence resulting from this system. This process asks authors to register their hypotheses and methods before data collection on a publicly available repository or by submitting a Registered Report. In the Registered Report format, authors submit a stage 1 manuscript to a participating journal that includes an introduction, methods, and any pilot data indicating the exploratory or confirmatory nature of the study. After a stage 1 peer review, the manuscript can then be offered in-principle acceptance, rejected, or sent back for revisions to improve the quality of the study. If accepted, the project is guaranteed publication, assuming the authors follow the data collection and analysis protocol. After data collection, authors re-submit a stage 2 manuscript that includes the results and discussion, and the study is evaluated on clarity and conformity with the planned analysis. In its final form, Registered Reports appear almost identical to a typical publication, but give readers confidence that the hypotheses and main analyses are less susceptible to bias from questionable research practices. From this perspective, we argue that inclusion of Registered Reports by researchers and journals will improve the transparency, replicability, and trust in sport and exercise science research. The preprint version of this work is available on SportR[Formula: see text]iv: https://osf.io/preprints/sportrxiv/fxe7a/.

4.
Eur J Nutr ; 59(3): 991-1000, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30945033

RESUMO

PURPOSE: This study aimed to examine the psychological factors (knowledge, barriers and facilitators) that can contribute to hydration-related behaviors (i.e., fluid intake) in the general population and how these relate to physical health. METHODS: A structured survey was developed to examine the links between hydration knowledge (29 items), attitudes about hydration (80 items), and fluid intake behavior (8 items) among US adults. Survey data from Phase 1 (n =301, US adults) psychometrically evaluated the items via item analysis (knowledge and fluid behavior) and factor analysis (attitudes). Phase 2 survey data (n =389, US adults and college students) refined and validated the new 16-item hydration knowledge measure, 4-item fluid intake behavior index, and 18-item attitude measure (barriers and facilitators of hydration-related behaviors) alongside indices of physical health (BMI and exercise behaviors). RESULTS: Participants had a moderate level of hydration knowledge (Phase 1: 10.91 ± 3.10; Phase 2: 10.87 ± 2.47). A five-factor measure of attitudes which assessed both facilitators (social pressure and attention to monitoring) and barriers (lack of effort, physical barriers and lack of a fluid container) to hydration demonstrated strong internal consistency (αs from 0.75 to 0.90). Attitudes about hydration-most notably barriers to hydration-were associated with indicators of health and with fluid intake behaviors, whereas hydration knowledge was not. CONCLUSIONS: Increasing hydration knowledge may be necessary for people who hold inaccurate information about hydration, but attitudes about hydration are likely to have a larger impact on fluid intake behaviors and health-related outcomes.

5.
Appl Physiol Nutr Metab ; 45(5): 500-512, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31618604

RESUMO

Cancer-associated bodyweight loss (cachexia) is a hallmark of many cancers and is associated with decreased quality of life and increased mortality. Hepatic function can dramatically influence whole-body energy expenditure and may therefore significantly influence whole-body health during cancer progression. The purpose of this study was to examine alterations in markers of hepatic metabolism and physiology during cachexia progression. Male C57BL/6J mice were injected with 1 × 106 Lewis Lung Carcinoma cells dissolved in 100 µL PBS and cancer was allowed to develop for 1, 2, 3, or 4 weeks. Control animals were injected with an equal volume of phosphate-buffered saline. Livers were analyzed for measures of metabolism, collagen deposition, protein turnover, and mitochondrial quality. Animals at 4 weeks had ∼30% larger livers compared with all other groups. Cancer progression was associated with altered regulators of fat metabolism. Additionally, longer duration of cancer development was associated with ∼3-fold increased regulators of collagen deposition as well as phenotypic collagen content, suggesting increased liver fibrosis. Mitochondrial quality control regulators appeared to be altered before any phenotypic alterations to collagen deposition. While induction of Akt was noted, downstream markers of protein synthesis were not altered. In conclusions, cancer cachexia progression is associated with hepatic pathologies, specifically liver fibrosis. Alterations to mitochondrial quality control mechanisms appear to precede this fibrotic phenotype, potentially suggesting mitochondrial mechanisms for the development of hepatic pathologies during the development and progression of cancer cachexia. Novelty Cachexia progression results in liver collagen deposition and fibrosis. Alterations in mitochondrial quality control may precede liver pathologies during cachexia.

6.
J Am Coll Nutr ; 39(3): 235-242, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31347984

RESUMO

Objective: Achieving and maintaining an optimal level of hydration has significant implications for both acute and chronic health, yet many hydration assessments are not feasible for the general public. Urinary frequency (UF) is a reliable method to self-assess hydration status in healthy individuals, and thirst can provide additional sensory information on adequacy of daily fluid intake volume (DFI). However, threshold values for these indices to detect optimal hydration have not been determined. In this study, we sought to determine threshold values for 24-hour UF and perceived thirst that could accurately distinguish between optimal and suboptimal hydration states.Methods: Thirty-two healthy adults (age 22 ± 3 years, body mass index 24.9 ± 4.1 kg/m2) collected urine over 24 hours on four separate occasions, where UF was recorded as well as thirst at each void using a numbered perceptual scale. Using urine osmolality as the criterion standard, all samples were either classified as representing an optimal (≤500 mOsm·kg-1) or suboptimal hydration status (>500 mOsm·kg-1).Results: A 24-hour UF ≤6 was able to detect suboptimal hydration with good accuracy (area under the curve [AUC] 0.815) and a 24-hour average perceived thirst rating > 3 ("a little thirsty") could detect it with reasonable accuracy (AUC 0.725). In addition, a UF ≤4 had a considerably higher positive likelihood ratio to detect suboptimal hydration versus a UF ≤6 (9.03 versus 2.18, respectively).Conclusions: These analyses suggest that individuals with a 24-hour UF ≤6 or perceiving themselves to be, on average, "a little thirsty" throughout the day are likely to be suboptimally hydrated and thus underconsuming an adequate DFI.

8.
Temperature (Austin) ; 6(3): 181-210, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31608303

RESUMO

The average environmental and occupational physiologist may find statistics are difficult to interpret and use since their formal training in statistics is limited. Unfortunately, poor statistical practices can generate erroneous or at least misleading results and distorts the evidence in the scientific literature. These problems are exacerbated when statistics are used as thoughtless ritual that is performed after the data are collected. The situation is worsened when statistics are then treated as strict judgements about the data (i.e., significant versus non-significant) without a thought given to how these statistics were calculated or their practical meaning. We propose that researchers should consider statistics at every step of the research process whether that be the designing of experiments, collecting data, analysing the data or disseminating the results. When statistics are considered as an integral part of the research process, from start to finish, several problematic practices can be mitigated. Further, proper practices in disseminating the results of a study can greatly improve the quality of the literature. Within this review, we have included a number of reminders and statistical questions researchers should answer throughout the scientific process. Rather than treat statistics as a strict rule following procedure we hope that readers will use this review to stimulate a discussion around their current practices and attempt to improve them. The code to reproduce all analyses and figures within the manuscript can be found at https://doi.org/10.17605/OSF.IO/BQGDH.

9.
Hum Mov Sci ; 66: 31-37, 2019 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-30913414

RESUMO

Standing is commonly recommended to reduce sedentary behavior in the workplace; however, constrained prolonged standing has also been linked to musculoskeletal symptoms, such as low back pain (LBP). Light physical activity breaks, such as walking, may change lumbar spine posture enough to reduce LBP during standing. This study assessed the effectiveness of inserting 5-minute walking breaks every 25 min for reducing prolonged standing-induced LBP development. Nineteen participants completed two bouts of standing lasting 2 h - one with a 5-minute walking break every 25 min and one with no breaks. Pain measures were completed throughout the trial to categorize participants as pain developers (PDs) or non-pain developers (non-PDs). Lumbar region kinematics angle and range of motion were measured continuously. In standing, 58% (11/19) of participants were PDs, compared to just 26% when walking breaks were inserted. Seventy-three percent (8/11) were categorized as non-PDs with walking breaks. Median lumbar flexion increased during walking compared to standing. Lumbar region range of motion in the coronal and transverse planes also increased during walking. The intermittent lumbar flexion may help decrease LBP during prolonged standing. These results demonstrate that walking breaks may help promote lumbar movement and reduce prolonged standing-induced LBP.

10.
PeerJ ; 6: e5868, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30397554

RESUMO

Background: Eating disorders are serious psychological disorders with long term health impacts. Athletic populations, tend to have higher incidences of eating disorders compared to the general population. Yet there is little known about athletes' eating disorder knowledge and how it relates to their confidence in their knowledge. Therefore, the purpose of our study was to evaluate collegiate female athletes' eating disorder (ED) knowledge and confidence in their knowledge. 51 participants were recruited from a National Association of Intercollegiate Athletics (NAIA) university in the mid-west and asked to complete a 30-question exam assessing one's knowledge of five different categories related to eating disorders. Confidence in the correctness of answers was assessed with a 5-point Likert-scale (1 = very unconfident, 5 = very confident). A one-way ANOVA was used to determine differences between scores on different categories and overall scores. A simple regression analysis was used to determine if confidence or age was predictive in knowledge scores. Results: The average score of participants was 69.1%, SD = 10.8% with an average confidence of 3.69/5, SD = 0.33. Athletes scored lowest with regards to Identifying Signs and Symptoms of EDs compared to other sub-scores (p < 0.05). There was no relationship between knowledge and confidence scores. Discussion: There is limited ED knowledge among collegiate female athletes. This may be problematic as many athletes appear confident in the correctness of their answers despite these low scores. Coaches should be aware of this lack of knowledge and work with clinical practitioners, such as dieticians, team physicians and athletic trainers to educate and monitor their athletes on eating disorders, specifically signs and symptoms.

11.
PeerJ ; 6: e5394, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30128190

RESUMO

Background: The independent effects of hypohydration and hyperthermia on cognition and mood is unclear since the two stresses often confound each other. Further, it is unknown if obese individuals have the same impairments during hyperthermia and hypohydration that is often observed in non-obese individuals. Methods: The current study was designed to assess the independent and combined effects of mild hypohydration and hyperthermia on cognition, mood, and mental task load in obese and non-obese females. Twenty-one healthy females participated in two passive heating trials, wherein they were either euhydrated or hypohydrated prior to and throughout passive heating. Cognition (ImPACT), mental task load (NASA-TLX), and mood (Brunel Mood Scale; BRUMS) were measured before and after a 1.0 °C increase in core temperature (TC). Results: After a 1.0 °C TC elevation, hypohydration resulted in greater (p < 0.05) body mass loss (-1.14 ± 0.48 vs -0.58 ± 0.48 kg; hypohydrated and euhydrated, respectively) and elevation in serum osmolality (292 ± 4 vs 282 ± 3 mOsm; p < 0.05) versus euhydration. Hypohydration, independent of hyperthermia, did not affect mental task load or mood (p > 0.05). Hyperthermia, regardless of hydration status, impaired (∼5 A.U) measures of memory-based cognition (verbal and visual memory), and increased mental task load, while worsening mood (p < 0.05). Interestingly, obese individuals had increased mental task load while hyperthermic compared to the non-obese individuals (p < 0.05) even while euhydrated. Hypohydration did not exacerbate any heat-related effects on cognition between obese and non-obese females (p > 0.05). Conclusion: These data indicate that hyperthermia independently impairs memory-based aspects of cognitive performance, mental task load, and leads to a negative mood state. Mild hypohydration did not exacerbate the effects of hyperthermia. However, obese individuals had increased mental task load during hyperthermia.

12.
Eur J Appl Physiol ; 118(10): 2249-2258, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30076480

RESUMO

PURPOSE: Standing workstations have recently been promoted as a healthy alternative to sitting. However, it is unknown how prolonged standing affects arterial stiffness, a prognostic indicator of cardiovascular health. The purpose of this study was twofold: to observe changes in arterial stiffness, as assessed by pulse wave velocity (PWV), with a 2-h bout of standing, and to determine if short, intermittent walking bouts provide a comparative advantage to standing alone. METHODS: Nineteen adults had arterial stiffness assessed by pulse wave velocity. Central (CPWV), upper peripheral (UPWV), and lower peripheral (LPWV) PWV were assessed before (supine), during standing (min 10, 60, and 120), and after (supine) the 2-h standing bout. In one trial, the participants stood at a standing desk immobile for 2 h. In the other trial, participants performed 5-min walking breaks after every 25 min of standing. RESULTS: After 2-h of standing, supine (85.8 ± 90.1 cm/s) and standing (303.4 ± 390.2 cm/s), LPWV increased independent of trial (i.e., main effect of time; p < 0.001). Walking breaks during 2 h of standing did not significantly attenuate these changes. In addition, standing CPWV decreased over time (- 38.5 ± 61.5 cm/s; p = 0.04). Yet, UPWV, standing or supine, did not change over the course of standing (p > 0.05). CONCLUSIONS: These findings indicate that prolonged standing increases the measures of arterial stiffness and there is no evidence that walk breaks attenuate this response.


Assuntos
Posição Ortostática , Rigidez Vascular , Adulto , Feminino , Humanos , Perna (Membro)/irrigação sanguínea , Masculino , Adulto Jovem
13.
Eur J Appl Physiol ; 118(8): 1703-1713, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29855792

RESUMO

INTRODUCTION: Obesity and hypohydration independently affect postsynaptic endothelial function, but it is unknown if hypohydration affects lean and obese individuals differently. PURPOSE: To examine the effect of hypohydration on postsynaptic cutaneous vasodilation and sweating in men with high and low adiposity (HI- and LO-BF, respectively). METHODS: Ten males with LO-BF and ten with HI-BF were instrumented for forearm microdialysis when euhydrated and hypohydrated. Changes in cutaneous vascular conductance (CVC) with intradermal infusion of sodium nitroprusside (SNP) and methacholine chloride (MCh) were assessed. Local sweat rate (LSR) was simultaneously assessed at the MCh site. At the end of the last dose, maximal CVC was elicited by delivering a maximal dose of SNP for 30 min to both sites with simultaneous local heating at the SNP site. The concentration of drug needed to elicit 50% of the maximal response (EC50) was compared between groups and hydration conditions. RESULTS: When euhydrated, EC50 of MCh-induced CVC was not different between LO- vs. HI-BF [- 3.04 ± 0.12 vs. - 2.98 ± 0.19 log (MCh) M, P = 0.841]. EC50 of SNP-induced CVC was higher in euhydrated HI- vs. LO-BF (- 1.74 ± 0.17 vs. - 2.13 ± 0.06 log (SNP) M, P = 0.034). Within each group, hydration status did not change MCh- or SNP-induced CVC (P > 0.05). LSR was not different between groups or hydration condition (P > 0.05). CONCLUSIONS: These data suggest reduced sensitivity of endothelium-independent vasodilation in individuals with high adiposity when euhydrated. However, hypohydration does not affect cutaneous vasodilation or local sweat rate differently between individuals with low or high adiposity.


Assuntos
Adiposidade , Desidratação/fisiopatologia , Sobrepeso/fisiopatologia , Pele/irrigação sanguínea , Sudorese , Vasodilatação , Adulto , Humanos , Masculino , Microvasos/inervação , Microvasos/fisiologia , Distribuição Aleatória
14.
J Sci Med Sport ; 21(12): 1180-1184, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29784554

RESUMO

Exercise, especially in the heat, can contribute to acute kidney injury, which can expedite chronic kidney disease onset. The additional stress of ibuprofen use is hypothesized to increase renal stress. OBJECTIVES: To observe the effects of endurance cycling in the heat on renal function. Secondarily, we investigated the effect of ibuprofen ingestion on kidney stress. DESIGN: Randomized, placebo controlled and observational methods were utilized. METHODS: Forty cyclists (52±9y, 21.7±6.5% body fat) volunteered and completed an endurance cycling event (5.7±1.2h) in the heat (33.2±5.0°C, 38.4±10.7% RH). Thirty-five participants were randomized to ingest a placebo (n=17) or 600mg ibuprofen (n=18) pre-event. A blood sample was drawn before and following the event. Serum creatinine was assessed by colorimetric assay. An ELISA was used to measure serum neutrophil gelatinase-associated lipocalin. Fractional excretion of sodium was calculated after urinary and serum electrolyte analyses. RESULTS: Placebo versus ibuprofen groups contributed no significant difference in any variable (p>0.05). Serum creatinine significantly increased from pre- (0.52±0.14mg/dL) to post-event (0.88±0.21mg/dL; p<0.001). Serum neutrophil gelatinase-associated lipocalin significantly increased (pre: 68.51±17.54ng/mL; post: 139.12±36.52ng/mL; p<0.001) and fractional excretion of sodium was significantly reduced from pre- (0.52±0.24%) to post-event (0.27±0.18%; p<0.001). CONCLUSIONS: Changes in renal biomarkers suggest mild acute kidney injury and reduced kidney function during a single bout of endurance cycling in the heat, without influence from moderate ibuprofen ingestion.


Assuntos
Lesão Renal Aguda/fisiopatologia , Ciclismo/fisiologia , Temperatura Alta/efeitos adversos , Ibuprofeno/uso terapêutico , Rim/fisiopatologia , Adulto , Biomarcadores/sangue , Creatinina/sangue , Método Duplo-Cego , Feminino , Humanos , Rim/efeitos dos fármacos , Lipocalina-2/sangue , Masculino , Pessoa de Meia-Idade , Resistência Física
15.
Clin Physiol Funct Imaging ; 38(3): 447-454, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-28444935

RESUMO

Consensus guidelines have attempted to standardize the measurement and interpretation of pulse wave velocity (PWV); however, guidelines have not addressed whether hydration status affects PWV. Moreover, multiple studies have utilized heat stress to reduce arterial stiffness which may lead to dehydration. This study utilized two experiments to investigate the effects of dehydration on PWV at rest and during passive heat stress. In experiment 1, subjects (n = 19) completed two trials, one in which they arrived euhydrated and one dehydrated (1·2[1·0]% body mass loss). In experiment 2, subjects (n = 11) began two trials euhydrated and in one trial did not receive water during heat stress, thus becoming dehydrated (1·6[0·6]% body mass loss); the other trial subjects remained euhydrated. Using Doppler ultrasound, carotid-to-femoral (central) and carotid-to-radial (peripheral) PWVs were measured. PWV was obtained at a normothermic baseline, and at a 0·5°C and 1°C elevation in rectal temperature (via passive heating). In experiment 1, baseline central PWV was significantly higher when euhydrated compared to dehydrated (628[95] versus 572[91] cm s-1 , respectively; P<0·05), but peripheral PWV was unaffected (861[117] versus 825[149] cm s-1 ; P>0·05). However, starting euhydrated and becoming dehydrated during heating in experiment 2 did not affect PWV measures (P>0·05), and independent of hydration status peripheral PWV was reduced when rectal temperature was elevated 0·5°C (-74[45] cm s-1 ; P<0·05) and 1·0°C (-70[48] cm s-1 ; P<0·05). Overall, these data suggest that hydration status affects measurements of central PWV in normothermic, resting conditions. Therefore, future guidelines should suggest that investigators ensure adequate hydration status prior to measures of PWV.


Assuntos
Desidratação/fisiopatologia , Transtornos de Estresse por Calor/fisiopatologia , Estado de Hidratação do Organismo , Análise de Onda de Pulso , Rigidez Vascular , Adulto , Regulação da Temperatura Corporal , Desidratação/diagnóstico , Ingestão de Líquidos , Feminino , Transtornos de Estresse por Calor/diagnóstico , Humanos , Masculino , Valor Preditivo dos Testes , Distribuição Aleatória , Reprodutibilidade dos Testes , Ultrassonografia Doppler , Equilíbrio Hidroeletrolítico , Adulto Jovem
16.
Mil Med ; 182(9): e1951-e1957, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28885961

RESUMO

BACKGROUND: The procedure of wrapping a heat casualty in ice-water soaked bed sheets to reduce core temperature has received little investigation, despite the practice and recommendation for its use in some military settings. Thus, the purpose of this study was to investigate the cooling efficacy of ice-sheet cooling (ISC) following exertional hyperthermia. METHODS: 13 (11 males, 2 females) participants (age = 23 ± 3 years, height = 176.5 ± 10.3 cm, mass = 78.6 ± 15.3 kg, body fat = 19.6 ± 8.6%, and body surface area = 1.95 ± 0.22 m2) volunteered to complete 2 randomized, crossover design trials on an outdoor recreation field (34.4 ± 1.4°C, 54.4 ± 4.1% relative humidity). Each trial consisted of exercise (self-paced 400-m warm-up, 1,609-m run, and 100-m sprints) followed by 15 minutes of either lying supine in the shade with no treatment (control [CON]) or being treated with ice-water soaked sheets wrapped around their body (ISC). Physiological (rectal temperature [Tre], heart rate, mean-weighted skin temperature) and perceptual measures (thermal sensation, rating of perceived exertion) were assessed after each exercise protocol, every 3 minutes during treatment, and every 5 minutes during recovery. FINDINGS: By design, there were no differences during exercise between ISC and CON for Tre (p = 0.16), skin temperature (p = 0.52), heart rate (p = 0.62), thermal sensation (p = 0.89), or rating of perceived exertion (p = 0.99). There were greater decreases in Tre at 3 (ISC 0.33 ± 0.26°C vs. CON 0.03 ± 0.30°C, p = 0.01) and 6 minutes (ISC 0.47 ± 0.27°C vs. CON 0.30 ± 0.19°C, p = 0.05) of treatment; however, the overall rate of cooling was not different between trials (CON 0.05 ± 0.02°C/min vs. ISC 0.06 ± 0.02°C/min, p = 0.72). Skin temperature (Tsk) was significantly reduced from 3 minutes (ISC 34.4 ± 1.7°C vs. CON 36.6 ± 0.5°C, p = 0.007) through 15 minutes (ISC 32.4 ± 1.5 vs. CON 36.1 ± 0.4°C, p < 0.001) of treatment. There was a trend for lower heart rate with ISC (p = 0.051). Thermal sensation was reduced from 3 minutes of treatment (ISC 3.5 ± 0.9 vs. CON 4.5 ± 0.6, p = 0.002) through 15 minutes (ISC 2.8 ± 1.0 vs. CON 3.9 ± 0.4, p = 0.005). DISCUSSION: ISC does not provide effective reduction in Tre following exertional hyperthermia compared to no treatment. However, perceptual benefits may warrant the use of ISC in settings where rapid reductions in core temperature are not a concern (i.e., recovery from exercise). Thus, clinicians should continue to utilize validated techniques (i.e., cold-water immersion) for the treatment of exertional heat illnesses.


Assuntos
Febre/terapia , Hipertermia Induzida/métodos , Hipertermia Induzida/normas , Esforço Físico , Adulto , Temperatura Corporal/fisiologia , Regulação da Temperatura Corporal/fisiologia , Feminino , Humanos , Hipertermia Induzida/efeitos adversos , Camada de Gelo , Masculino , Monitorização Fisiológica/instrumentação , Monitorização Fisiológica/métodos , Gravidade Específica
17.
Eur J Appl Physiol ; 117(8): 1679-1687, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28612122

RESUMO

PURPOSE: Prior evidence indicates that acute heat stress and aerobic exercise independently reduce arterial stiffness. The combined effects of exercise and heat stress on PWV are unknown. The purpose of this study was to determine the effects of heat stress with passive heating and exercise in the heat on arterial stiffness. METHODS: Nine participants (n = 3 females, 47 ± 11 years old; 24.1 ± 2.8 kg/m2) completed four trials. In a control trial, participants rested supine (CON). In a passive heating trial (PH), participants were heated with a water-perfusion suit. In two other trials, participants cycled at ~50% of [Formula: see text] in a hot (~40 °C; HC trial) or cool (~15 °C; CC trial) environment. Arterial stiffness, measured by PWV, was obtained at baseline and after each intervention (immediately, 15, 30, 45, and 60 min post). Central PWV (C PWV) was assessed between the carotid/femoral artery sites. Upper and lower peripheral PWV was assessed using the radial/carotid (U PWV) and dorsalis pedis/femoral (L PWV) artery sites. The mean body temperature (T B) was calculated from the skin and rectal temperatures. RESULTS: No significant changes in T B were observed during the CON and CC trials. As expected, the PH and HC trials elevated T B 2.69 ± 0.23 °C and 1.67 ± 0.27 °C, respectively (p < 0.01). PWV did not change in CON, CC, or HC (p > 0.05). However, in the PH trial, U PWV was reduced immediately (-107 ± 81 cm/s) and 15 min (-93 ± 82 cm/s) post-heating (p < 0.05). CONCLUSIONS: Heat stress via exercise in the heat does not acutely change arterial stiffness. However, passive heating reduces U PWV, indicating that heat stress has an independent effect on PWV.


Assuntos
Exercício Físico/fisiologia , Transtornos de Estresse por Calor/fisiopatologia , Temperatura Alta , Rigidez Vascular/fisiologia , Adulto , Velocidade do Fluxo Sanguíneo/fisiologia , Temperatura Corporal/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
18.
J Strength Cond Res ; 31(3): 638-643, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27552210

RESUMO

Caldwell, AR, Tucker, MA, Butts, CL, McDermott, BP, Vingren, JL, Kunces, LJ, Lee, EC, Munoz, CX, Williamson, KH, Armstrong, LE, and Ganio, MS. Effect of caffeine on perceived soreness and functionality following an endurance cycling event. J Strength Cond Res 31(3): 638-643, 2017-Caffeine can reduce muscle pain during exercise; however, the efficacy of caffeine in improving muscle soreness and recovery from a demanding long-duration exercise bout has not been established. The purpose of this study was to investigate the effects of caffeine intake on ratings of perceived muscle soreness (RPMS) and perceived lower extremity functionality (LEF) following the completion of a 164-km endurance cycling event. Before and after cycling RPMS (1-to-6; 6 = severe soreness) and LEF (0-to-80; 80 = full functionality) were assessed by questionnaires. Subjects ingested 3 mg/kg body mass of caffeine or placebo pills in a randomized, double-blind fashion immediately after the ride and for the next 4 mornings (i.e., ∼800 hours) and 3 afternoons (i.e., ∼1200 hours). Before each ingestion, RPMS and LEF were assessed. Afternoon ratings of LEF were greater with caffeine ingestion the first day postride (65.0 ± 6.1 vs. 72.3 ± 6.7; for placebo and caffeine, respectively; p = 0.04), but at no other time points (p > 0.05). The caffeine group tended to have lower overall RPMS in the afternoon versus placebo (i.e., main effect of group; 1.1 ± 0.2 vs. 0.5 ± 0.2; p = 0.09). Afternoon RPMS for the legs was significantly lower in the caffeine group (main effect of caffeine; 1.3 ± 0.2 vs. 0.5 ± 0.3; p = 0.05). In conclusion, ingesting caffeine improved RPMS for the legs, but not LEF in the days following an endurance cycling event. Athletes may benefit from ingesting caffeine in the days following an arduous exercise bout to relieve feelings of soreness and reduced functionality.


Assuntos
Atletas , Ciclismo/fisiologia , Cafeína/uso terapêutico , Mialgia/tratamento farmacológico , Resistência Física/fisiologia , Adulto , Cafeína/administração & dosagem , Método Duplo-Cego , Teste de Esforço , Feminino , Humanos , Extremidade Inferior/fisiologia , Masculino , Pessoa de Meia-Idade , Percepção/efeitos dos fármacos
19.
J Appl Physiol (1985) ; 122(1): 142-152, 2017 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-27789773

RESUMO

It is unclear whether men with low body fat (LO-BF) have impaired thermoregulation during exercise heat stress compared with those with high body fat (HI-BF) when euhydration (EU) is maintained. Furthermore, in LO-BF individuals, hypohydration (HY) impairs thermoregulatory responses during exercise heat stress, but it is unknown whether this occurs in HI-BF counterparts. The purpose of this study was to test the hypotheses that men with HI-BF have impaired thermoregulatory responses to exercise heat stress and that HY further exacerbates these impairments vs. LO-BF. Men with LO-BF [n = 11, body mass (BM) 73.9 ± 8.5 kg, BF% 13.6 ± 3.8] and HI-BF (n = 9, BM 89.6 ± 6.9 kg, BF% 30.2 ± 4.1), in a randomized crossover design, performed 60 min of upright cycling in a hot environment (40.3 ± 0.4°C, relative humidity 32.5 ± 1.9%) at a metabolic heat production rate of 6 W/kg BM and finished exercise either euhydrated (EU; 0.3 ± 1.2 vs. 0.3 ± 0.9% BM loss) or HY (-2.5 ± 1.1 vs. -1.7 ± 1.5% BM loss). Changes in rectal temperature (ΔTrec), local sweat rate (ΔLSR), and cutaneous vascular conductance (ΔCVC; %max) were measured throughout. When EU, LO-BF and HI-BF had similar CVC and LSR responses (P > 0.05); however, LO-BF had a lower ΔTrec vs. HI-BF (0.92 ± 0.35 vs. 1.31 ± 0.32°C, P = 0.021). Compared with EU, HY increased end-exercise ΔTrec in LO-BF (0.47 ± 0.37°C, P < 0.01) but not in HI-BF (-0.06 ± 0.29°C, P > 0.05). HY, compared with EU, did not affect ΔLSR and ΔCVC in either group (P > 0.05). We conclude that, when euhydrated, men with HI-BF have a greater increase in Trec vs. LO-BF but similar CVC and LSR. HY exacerbates increases in Trec in LO-BF but not HI-BF. NEW & NOTEWORTHY: This is the first known investigation to compare thermoregulatory responses to exercise heat stress between men with high and low body fat (BF) in a physiologically uncompensable environment while simultaneously examining the confounding influence of hydration status. Both groups demonstrated similar sweating and cutaneous vasodilatory responses when euhydrated, despite vast differences in rectal temperature. Furthermore, in contrast to low BF, individuals with high BF demonstrated similar increases in core body temperature when either euhydrated or hypohydrated.


Assuntos
Tecido Adiposo/fisiologia , Regulação da Temperatura Corporal/fisiologia , Desidratação/fisiopatologia , Exercício Físico/fisiologia , Adulto , Temperatura Corporal/fisiologia , Transtornos de Estresse por Calor/fisiopatologia , Temperatura Alta , Humanos , Masculino , Sudorese/fisiologia , Termogênese/fisiologia , Adulto Jovem
20.
J Nutr Metab ; 2016: 1089653, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27630772

RESUMO

Curcumin, a turmeric extract, may protect against cardiovascular diseases by enhancing endothelial function. In this randomized controlled double-blind parallel prospective study, fifty-nine healthy adults were assigned to placebo, 50 mg (50 mg), or 200 mg (200 mg) curcumin, for 8 weeks. The higher curcumin (200 mg) supplementation produced a dose-mediated improvement in endothelial function measured by flow-mediated dilation (FMD). The outcome was a clinically substantial 3.0% increase (90% CI 0.7 to 5.3%, p = 0.032; benefit : harm odds ratio 546 : 1) with the 200 mg dose, relative to placebo. The 50 mg dose also increased FMD relative to placebo by 1.7% (-0.6 to 4.0%, p = 0.23; 25 : 1), but the outcome was not clinically decisive. In apparently healthy adults, 8 weeks of 200 mg oral curcumin supplementation resulted in a clinically meaningful improvement in endothelial function as measured by FMD. Oral curcumin supplementation may present a simple lifestyle strategy for decreasing the risk of cardiovascular diseases. This trial was registered at ISRCTN registry (ISRCTN90184217).

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