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Pałka T, Rydzik Ł, Koteja PM, Piotrowska A, Bagińska M, Ambroży T, Angelova-Igova B, Javdaneh N, Wiecha S, Filip-Stachnik A, Tota Ł. Effect of Various Hydration Strategies on Work Intensity and Selected Physiological Indices in Young Male Athletes during Prolonged Physical Exercise at High Ambient Temperatures. J Clin Med 2024; 13:982. [PMID: 38398295 PMCID: PMC10888716 DOI: 10.3390/jcm13040982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 01/26/2024] [Accepted: 02/06/2024] [Indexed: 02/25/2024] Open
Abstract
Background: In high temperatures, adequate hydration is vital for sustained physical exercise. This study explores the effect of three hydration strategies on physiological indices and work intensity. Methods: The research involved 12 healthy males who engaged in three test series, each separated by a one-week interval. During the trials, participants underwent a 120 min cycling session in a thermal climate chamber (temperature: 31 ± 2 °C, humidity: 60 ± 3%, air movement: <1 m/s). Measurements of rectal temperature (Tre) and heart rate (HR), and assessment of subjective workload perception, and thermal comfort were made both before and during the exercise. The computation of the physical strain index (PSI) relied on Tre and HR values. Three hydration strategies (isotonic drink, water, and no hydration) were administered before, during, and after the exercise. Results: Regardless of the hydration strategy, the participants' mean body mass decreased as a result of the exercise. Statistically significant differences in HR were observed between the no-hydration and water groups (p < 0.036). The mean PSI values significantly varied between hydration strategies, with the no hydration group exhibiting a higher PSI compared to the isotonic drink or water groups (p < 0.001). Conclusions: All hydration strategies contribute to thermoregulatory processes and mitigate the rise in internal body temperature during sustained physical exercise in elevated ambient temperatures.
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Affiliation(s)
- Tomasz Pałka
- Department of Physiology and Biochemistry, Faculty of Physical Education and Sport, University of Physical Education, 31-571 Kraków, Poland; (T.P.); (Ł.T.)
| | - Łukasz Rydzik
- Institute of Sports Sciences, University of Physical Education, 31-571 Kraków, Poland; (P.M.K.); (T.A.)
| | - Piotr Michał Koteja
- Institute of Sports Sciences, University of Physical Education, 31-571 Kraków, Poland; (P.M.K.); (T.A.)
| | - Anna Piotrowska
- Department of Chemistry and Biochemistry, Faculty of Physiotherapy, University of Physical Education, 31-571 Kraków, Poland;
| | - Małgorzata Bagińska
- Institute of Biomedical Sciences, Department of Physiology and Biochemistry, University of Physical Education, 31-571 Kraków, Poland;
| | - Tadeusz Ambroży
- Institute of Sports Sciences, University of Physical Education, 31-571 Kraków, Poland; (P.M.K.); (T.A.)
| | - Boryana Angelova-Igova
- National Sports Academy Vassil Levski, Philosophy and Sociology of Sport, 1700 Sophia, Bulgaria;
| | - Norollah Javdaneh
- Department of Biomechanics and Sports Injuries, Kharazmi University of Tehran, Tehran 14911-15719, Iran;
| | - Szczepan Wiecha
- Department of Physical Education and Health in Biala Podlaska, Faculty in Biala Podlaska, Jozef Pilsudski University of Physical Education, 00-968 Warsaw, Poland
| | - Aleksandra Filip-Stachnik
- Department of Sports Medicine and Human Nutrition, Institute of Biomedical Sciences, University of Physical Education, 31-571 Kraków, Poland;
| | - Łukasz Tota
- Department of Physiology and Biochemistry, Faculty of Physical Education and Sport, University of Physical Education, 31-571 Kraków, Poland; (T.P.); (Ł.T.)
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Wardenaar FC, Whitenack L, Vento KA, Seltzer RGN, Siegler J, Kavouras SA. Validity of combined hydration self-assessment measurements to estimate a low vs. high urine concentration in a small sample of (tactical) athletes. Eur J Nutr 2024; 63:185-193. [PMID: 37794214 DOI: 10.1007/s00394-023-03254-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 09/08/2023] [Indexed: 10/06/2023]
Abstract
PURPOSE Relationships between body weight, urine color (Uc), and thirst level (WUT) have been proposed as a simple and inexpensive self-assessment method to predict dehydration. This study aimed to determine if this method also allowed us to accurately identify a low vs. high urine concentration in (tactical) athletes. METHODS A total of n = 19 Army Reserve Officer Training Corps cadets and club sports athletes (22.7 ± 3.8 years old, of which 13 male) were included in the analysis, providing morning body weight, thirst sensation, and Uc for five consecutive days. Each item received a score 0 or 1, resulting in a WUT score ranging from 0 (likely hydrated) to 3 (very likely dehydrated). WUT model and individual item outcomes were then compared with a ≥ 1.020 urine specific gravity (USG) cut-off indicating a high urine concentration, using descriptive comparisons, generalized linear mixed models, and logistic regression (to calculate the area under the curve (AUC)). RESULTS WUT score was not significantly predictive of urine concentration, z = 1.59, p = 0.11. The AUC ranged from 0.54 to 0.77 for test days, suggesting a fair AUC on most days. Only Uc was significantly related to urine concentration, z = 2.49, p = 0.01. The accuracy of the WUT model for correctly classifying urine samples with a high concentration was 68% vs. 51% of samples with a low concentration, resulting in an average accuracy of 61%. CONCLUSION This study shows that WUT scores were not predictive of urine concentration, and the method did not substantially outperform the accuracy of Uc scoring alone.
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Affiliation(s)
- Floris C Wardenaar
- College of Health Solutions, Arizona State University, Phoenix, AZ, USA.
| | - Lauren Whitenack
- College of Health Solutions, Arizona State University, Phoenix, AZ, USA
| | - Kaila A Vento
- College of Health Solutions, Arizona State University, Phoenix, AZ, USA
| | - Ryan G N Seltzer
- College of Health Solutions, Arizona State University, Phoenix, AZ, USA
| | - Jason Siegler
- College of Health Solutions, Arizona State University, Phoenix, AZ, USA
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Takada S, Otsuka J, Okamoto Y, Watanabe D, Aoki M, Fujii N, Kenny GP, Enoki Y, Maejima D, Amano T. Effects of ingestion of isomaltulose beverage on plasma volume and thermoregulatory responses during exercise in the heat. Eur J Appl Physiol 2022; 122:2615-2626. [DOI: 10.1007/s00421-022-05044-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 09/07/2022] [Indexed: 11/28/2022]
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Schroeder N. Evidence-Based Nutritional Strategies to Enhance Athletic Performance. Strength Cond J 2022. [DOI: 10.1519/ssc.0000000000000642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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5
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Campbell EH, Irving R, McFarlane S, Dilworth L, Poudevigne M, Bailey J. Evidence that variations in pre-training hydration status are related to the frequency of endurance training in elite adolescent sprinters. J Sports Med Phys Fitness 2021; 61:1620-1628. [PMID: 33586933 DOI: 10.23736/s0022-4707.21.12025-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Although the effect of dehydration on performance is widely studied, limited data concerning the levels of risk training types pose to hydration status exists. This study sought to determine: (a) pre-training hydration status in adolescent sprinters relative to non-athletes, (b) changes in hydration markers across a season of adolescent sprinters relative to non-athletes, and (c) if frequency of training type explains unique variance in hydration. METHODS Hydration [via pre-training urine osmolality (UOsm) and thirst perception (TP)], daily water intake (TWI) [via 24-h food/fluid diaries] and frequencies of resistance, endurance and sprint training types (via training regime questionnaires) were assessed in 26 sprinters (age: 15.6±1.9 years) and 26 non-athletes (age: 16.0±1.6 years), during 4 mesocycles [general (T1) and specific (T2) preparation; pre-competitive (T3) and peaking (T4) phases], over 26 weeks. RESULTS Most athletes (62%-81%) and non-athletes (73%-92%) were underhydrated (UOsm>700 mOsmol/kg) pre-training across the season, despite a low TP. There were significant time (p =.042) and group (p =.006) effects, and a main group by time interaction for UOsm (p =.006) but not TP across the season, after controlling for TWI. Greater UOsm (in mOsmol/kg) were observed during T1 (906.3±250.1) and T2 (934.5±257.0) compared to T3 (852.1±268.8) and T4 (854.2±218.8). There was no significant change across the season for non-athletes. Frequencies of endurance training were positively associated with UOsm and explained unique variances across the season (R2 range from 7%-16%). CONCLUSIONS Underhydration is high in the adolescent population. Training type may be related to the variations in hydration throughout a season, which may help to inform hydration practices of sprint athletes.
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Affiliation(s)
- Eon H Campbell
- Biochemistry Section, Department of Basic Medical Sciences, The University of the West Indies, Mona, Jamaica -
| | - Rachael Irving
- Biochemistry Section, Department of Basic Medical Sciences, The University of the West Indies, Mona, Jamaica
| | - Shelly McFarlane
- Caribbean Institute for Health Research, The University of the West Indies at Mona, Mona, Jamaica
| | - Lowell Dilworth
- Department of Pathology, The University of the West Indies at Mona, Mona, Jamaica
| | - Melanie Poudevigne
- Health and Fitness Management, Clayton State University, Morrow, GA, USA
| | - Janel Bailey
- Biochemistry Section, Department of Basic Medical Sciences, The University of the West Indies, Mona, Jamaica
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Morris NB, Levi M, Morabito M, Messeri A, Ioannou LG, Flouris AD, Samoutis G, Pogačar T, Bogataj LK, Piil JF, Nybo L. Health vs. wealth: Employer, employee and policy-maker perspectives on occupational heat stress across multiple European industries. Temperature (Austin) 2020; 8:284-301. [PMID: 34485621 PMCID: PMC8409781 DOI: 10.1080/23328940.2020.1852049] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 01/16/2023] Open
Abstract
Successful implementation of cooling strategies obviously depends on identifying effective interventions, but in industrial settings, it is equally important to consider feasibility and economic viability. Many cooling interventions are available, but the decision processes affecting adoption by end-users are not well elucidated. We therefore arranged two series of meetings with stakeholders to identify knowledge gaps, receive feedback on proposed cooling interventions, and discuss factors affecting implementation of heat-health interventions. This included four meetings attended by employers, employees, and health and safety officers (n = 41), and three meetings attended primarily by policy makers (n = 74), with feedback obtained via qualitative and quantitative questionnaires and focus group discussions. On a 10-point scale, both employers and employees valued worker safety (9.1 ± 1.8; mean±SD) and health (8.5 ± 1.9) as more important than protecting company profits (6.3 ± 2.3). Of the respondents, 41% were unaware of any cooling strategies at their company and of those who were aware, only 30% thought the interventions were effective. Following presentation of proposed interventions, the respondents rated "facilitated hydration", "optimization of clothing/protective equipment", and "rescheduling of work tasks" as the top-three preferred solutions. The main barriers for adopting cooling interventions were cost, feasibility, employer perceptions, and legislation. In conclusion, preventing negative health and safety effects was deemed to be more important than preventing productivity loss. Regardless of work sector or occupation, both health and wealth were emphasized as important parameters and considered as somewhat interrelated. However, a large fraction of the European worker force lacks information on effective measures to mitigate occupational heat stress. List of abbreviations: OH-Stress: Occupational heat stress; WBGT: Wet Bulb Globe Temperature.
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Affiliation(s)
- Nathan B. Morris
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
- Centre for Technology Research and Innovation (CETRI), Lemesos, Cyprus
| | - Miriam Levi
- Epidemiology Unit, Department of Prevention, Local Health Authority Tuscany Center, Florence, Italy
| | - Marco Morabito
- Institute of Bioeconomy (IBE), National Research Council, Florence, Italy
- Center of Bioclimatology (CIBIC), University of Florence, Florence, Italy
| | - Alessandro Messeri
- Institute of Bioeconomy (IBE), National Research Council, Florence, Italy
- Center of Bioclimatology (CIBIC), University of Florence, Florence, Italy
| | - Leonidas G. Ioannou
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Andreas D. Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | | | - Tjaša Pogačar
- Department of Agronomy, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Lučka Kajfež Bogataj
- Department of Agronomy, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Jacob F. Piil
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Lars Nybo
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
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Mendes J, Padrão P, Moreira P, Santos A, Borges N, Afonso C, Negrão R, Amaral TF. Handgrip Strength and Its Association With Hydration Status and Urinary Sodium-to-Potassium Ratio in Older Adults. J Am Coll Nutr 2019; 39:192-199. [PMID: 31381481 DOI: 10.1080/07315724.2019.1633439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Objective: Older adults present higher risk of functional disability detected by handgrip strength and an increased risk of poor health conditions, such as dehydration and low values of the sodium-to-potassium (Na/K) ratio. This study aimed to quantify the association of hydration status and Na/K ratio with handgrip strength, based on the urinary excretion of older adults.Methods: A cross-sectional study was conducted in 735 older adults ≥ 65 years old. Handgrip strength was measured with a Jamar Dynamometer and low values were defined according to body mass index and to sex-specific cutoff points. The hydration status was evaluated based on free water reserve. Sodium and potassium intake were evaluated after converting 24-hour urinary sodium and potassium excretion, respectively. A logistic regression model was used to estimate the probability of presenting low handgrip strength, according to risk of hypohydration and to quartiles of Na/K, stratified by sex and adjusted for potential confounders.Results: The adjusted odds ratio (OR) for presenting low handgrip strength was higher in women at risk of hypohydration, but this association was not found in men. Both women and men with the highest values of Na/K ratio presented higher adjusted OR for low handgrip strength (OR in women was 2.03; 95% confidence interval [CI]: 1.12-3.68, and in men was 2.19; 95% CI: 1.11-4.29).Conclusions: The risk of hypohydration was directly associated with low handgrip strength in older women. In older adults, higher values of urinary Na/K ratio were also directly associated with low handgrip strength.
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Affiliation(s)
- Joana Mendes
- Department of Biomedicine, Biochemistry Unit, Faculty of Medicine, University of Porto, Porto, Portugal.,I3S-Institute for Research and Innovation in Health, University of Porto, Porto, Portugal
| | - Patrícia Padrão
- Faculty of Nutrition and Food Science, University of Porto, Porto, Portugal.,EPI Unit, Institute of Public Health, University of Porto, Porto, Portugal
| | - Pedro Moreira
- Faculty of Nutrition and Food Science, University of Porto, Porto, Portugal.,EPI Unit, Institute of Public Health, University of Porto, Porto, Portugal.,The Research Centre in Physical Activity, Health and Leisure, University of Porto, Porto, Portugal
| | - Alejandro Santos
- I3S-Institute for Research and Innovation in Health, University of Porto, Porto, Portugal.,Faculty of Nutrition and Food Science, University of Porto, Porto, Portugal
| | - Nuno Borges
- Faculty of Nutrition and Food Science, University of Porto, Porto, Portugal.,CINTESIS-Centre for Health Technology and Services Research, Porto, Portugal
| | - Cláudia Afonso
- Faculty of Nutrition and Food Science, University of Porto, Porto, Portugal
| | - Rita Negrão
- Department of Biomedicine, Biochemistry Unit, Faculty of Medicine, University of Porto, Porto, Portugal.,I3S-Institute for Research and Innovation in Health, University of Porto, Porto, Portugal
| | - Teresa F Amaral
- Faculty of Nutrition and Food Science, University of Porto, Porto, Portugal.,UISPA-IDMEC, Faculty of Engineering, University of Porto, Porto, Portugal
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Variability of Body Mass and Urine Specific Gravity in Elite Male Field Hockey Players During a Pre-Olympic Training Camp. Int J Sport Nutr Exerc Metab 2019; 29:46-50. [PMID: 29893591 DOI: 10.1123/ijsnem.2018-0121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 05/23/2018] [Indexed: 11/18/2022]
Abstract
This field-based observational study was designed to examine the intraindividual variation of first morning body mass and urine specific gravity (Usg) in male hockey players (n = 22) during a 10-day training camp. It was also designed to evaluate the prevalence and interrelationship of morning hypohydration and postmatch dehydration using Usg and changes in body mass, respectively. Body mass and Usg were measured upon waking; body mass was also measured before and after matches. Individual means, SD, and coefficient of variation (CV) were calculated for morning body mass and Usg using 3, 6, and 8 days. Daily prevalence for euhydration and postmatch dehydration using morning Usg (<1.020) and changes in body mass (>-2%), respectively, were determined. Measurement of morning body mass and Usg for 3 days had low variability (CV < 1%) with no improvement at 6 or 8 days. Between 36% and 73% of players were considered euhydrated based on morning Usg. Postmatch body mass was reduced >1% in 50-85% of players, with up to 40% experiencing changes >-2%. Postmatch changes in body mass were unrelated to Usg the subsequent morning. These outcomes can be helpful in establishing criteria for detecting meaningful changes in morning body mass and Usg in similar settings, helping to monitor hydration status in elite male athletes. Despite ample fluid availability and consumption, many players experienced hypohydration and dehydration during the camp, indicating that careful monitoring and an individual fluid replacement approach are warranted in these environments.
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Jeon S, Cho K, Ok G, Lee S, Park H. Weight loss practice, nutritional status, bone health, and injury history: A profile of professional jockeys in Korea. J Exerc Nutrition Biochem 2018; 22:27-34. [PMID: 30343556 PMCID: PMC6199486 DOI: 10.20463/jenb.2018.0021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 09/18/2018] [Indexed: 01/01/2023] Open
Abstract
[Purpose] The purpose of this study was to investigate the impact of weight loss practices on nutritional status, bone health, and injury history among Korean professional jockeys. [Methods] Forty-three male jockeys completed a questionnaire to assess their weight loss practices. Of these, 10 jockeys were selected for in-depth assessment of their nutritional status, bone health, and injury history. [Results] The questionnaires revealed that 81.4% of jockeys lost weight every week mainly by dieting and/or exercising. None of the jockeys consumed enough food during the weight loss period. Two jockeys were diagnosed with osteopenia and one was diagnosed with osteoporosis. Only history of fracture showed a significant correlation with low bone mineral density. All jockeys had more than one injury experience throughout their career. Fracture was the most common type of injury, occurring during practice and/or competition and caused mainly by difficulties in handling the horses. [Conclusion] Professional jockeys in Korea use extreme weight loss methods. Their repeated periods of poor nutritional intake may result in seriously low bone mineral density, which may aggravate injuries sustained during horse races. Implementation of balanced dietary programs and delivery of health education on weight management are urgently required.
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Zubac D, Reale R, Karnincic H, Sivric A, Jelaska I. Urine specific gravity as an indicator of dehydration in Olympic combat sport athletes; considerations for research and practice. Eur J Sport Sci 2018; 18:920-929. [PMID: 29746803 DOI: 10.1080/17461391.2018.1468483] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Urine specific gravity (USG) is the most commonly reported biochemical marker used in research and applied settings to detect fluid deficits in athletes, including those participating in combat sports. Despite the popularity of its use, there has been a growing debate regarding the diagnostic accuracy and the applicability of USG in characterizing whole-body fluid status and fluctuations. Moreover, recent investigations report universally high prevalence of hypohydration (∼90%) via USG assessment in combat sport athletes, often in spite of stable body-mass. Given the widespread use in both research and practice, and its use in a regulatory sense as a 'hydration test' in combat sports as a means to detect dehydration at the time of weigh-in; understanding the limitations and applicability of USG assessment is of paramount importance. Inconsistencies in findings of USG readings, possibly as a consequence of diverse methodological research approaches and/or overlooked confounding factors, preclude a conclusive position stand within current combat sports research and practice. Thus the primary aim of this paper is to critically review the literature regarding USG assessment of hydration status in combat sports research and practice. When taken on balance, the existing literature suggests: the use of laboratory derived benchmarks in applied settings, inconsistent sampling methodologies, the incomplete picture of how various confounding factors affect end-point readings, and the still poorly understood potential of renal adaptation to dehydration in combat athletes; make the utility of hydration assessment via USG measurement quite problematic, particularly when diet and training is not controlled.
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Affiliation(s)
- Damir Zubac
- a Science and Research Center Koper , Institute for Kinesiology Research , Koper , Slovenia.,c Faculty of Kinesiology , University of Split , Split , Croatia
| | - Reid Reale
- b Gatorade Sports Science Institute , Bradenton , FL , USA
| | - Hrvoje Karnincic
- c Faculty of Kinesiology , University of Split , Split , Croatia
| | | | - Igor Jelaska
- c Faculty of Kinesiology , University of Split , Split , Croatia
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Coker NA, Wells AJ, Gepner Y. Effect of Heat Stress on Measures of Running Performance and Heart Rate Responses During a Competitive Season in Male Soccer Players. J Strength Cond Res 2018; 34:1141-1149. [PMID: 29373425 DOI: 10.1519/jsc.0000000000002441] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Coker, NA, Wells, AJ, and Gepner, Y. The effect of heat stress on measures of running performance and heart rate responses during a competitive season in male soccer players. J Strength Cond Res 34(4): 1141-1149, 2020-Measures of running performance and heart rate (HR) responses to match play during 3 different heat stress (HS) conditions were assessed in 7 National Collegiate Athletic Association (NCAA) Division I male soccer players. Total distance and distance covered within distinct velocity zones (walking [WALK], jogging [JOG], low-speed running, high-speed running, sprinting [SPRINT], low-intensity running [LIR], and high-intensity running [HIR]) were assessed using global positioning system units for more than 12 matches. Heat stress was monitored during each match, and matches were defined as low (HSlow, n = 4), moderate (HSmod, n = 4), or high (HShigh, n = 4) HS. Minutes played were significantly different across HS conditions (p = 0.03). Therefore, distance covered within each movement velocity was assessed relative to minutes played and as a percentage of total playing time. WALKrel was significantly greater during HShigh compared with HSlow (p = 0.035). LIRrel was significantly greater during HSmod (p = 0.015) compared with HSlow. A trend was observed for %WALK being higher during HShigh compared with HSlow (p = 0.066). %LIR was significantly greater during HShigh compared with HSlow (p = 0.048). High-intensity running was not significantly different across HS conditions. Percent of time spent >85% HRmax was significantly greater during HShigh (p = 0.002) and HSmod (p < 0.001) compared to HSlow. Percent of time spent between 65-84% HRmax was significantly greater during HSlow compared to HShigh (p < 0.001). Results indicate that HS resulted in increased LIR and %HR≥85, while HIR was maintained. High-intensity running performance may be conserved through decreased playing time or the adoption of pacing strategies. This may assist coaches in altering player management strategies to optimize team performance.
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Affiliation(s)
- Nicholas A Coker
- Institute of Exercise Physiology and Wellness, Department of Educational and Human Sciences, University of Central Florida, Orlando, Florida
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Otte im Kampe E, Kovats S, Hajat S. Impact of high ambient temperature on unintentional injuries in high-income countries: a narrative systematic literature review. BMJ Open 2016; 6:e010399. [PMID: 26868947 PMCID: PMC4762150 DOI: 10.1136/bmjopen-2015-010399] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
OBJECTIVES Given the likelihood of increased hot weather due to climate change, it is crucial to have prevention measures in place to reduce the health burden of high temperatures and heat waves. The aim of this review is to summarise and evaluate the evidence on the effects of summertime weather on unintentional injuries in high-income countries. DESIGN 3 databases (Global Public Health, EMBASE and MEDLINE) were searched by using related keywords and their truncations in the title and abstract, and reference lists of key studies were scanned. Studies reporting heatstroke and intentional injuries were excluded. RESULTS 13 studies met our inclusion criteria. 11 out of 13 studies showed that the risk of unintentional injuries increases with increasing ambient temperatures. On days with moderate temperatures, the increased risk varied between 0.4% and 5.3% for each 1 °C increase in ambient temperature. On extreme temperature days, the risk of injuries decreased. 2 out of 3 studies on occupational accidents found an increase in work-related accidents during high temperatures. For trauma hospital admissions, 6 studies reported an increase during hot weather, whereas 1 study found no association. The evidence for impacts on injuries by subgroups such as children, the elderly and drug users was limited and inconsistent. CONCLUSIONS The present review describes a broader range of types of unintentional fatal and non-fatal injuries (occupational, trauma hospital admissions, traffic, fire entrapments, poisoning and drug overdose) than has previously been reported. Our review confirms that hot weather can increase the risk of unintentional injuries and accidents in high-income countries. The results are useful for injury prevention strategies.
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Affiliation(s)
- Eveline Otte im Kampe
- Department of Social and Environmental Health Research, London School of Hygiene and Tropical Medicine, London, UK
| | - Sari Kovats
- Department of Social and Environmental Health Research, London School of Hygiene and Tropical Medicine, London, UK
| | - Shakoor Hajat
- Department of Social and Environmental Health Research, London School of Hygiene and Tropical Medicine, London, UK
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13
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Ozkan I, Ibrahim CH. Dehydration, skeletal muscle damage and inflammation before the competitions among the elite wrestlers. J Phys Ther Sci 2016; 28:162-8. [PMID: 26957750 PMCID: PMC4755996 DOI: 10.1589/jpts.28.162] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 10/14/2015] [Indexed: 11/24/2022] Open
Abstract
[Purpose] The present study aimed to identify weight-loss and hydration levels before competitions among elite wrestlers and determine the skeletal muscle damage and inflammation levels after dehydration. [Subjects] Seventy-two elite wrestlers who participated in the Turkish Wrestling Championship. [Methods] With the help of specialists, 5 cc of blood were drawn from the forearm veins of the wrestlers. Laboratory analyses of Na(+), BUN, Glucose, CK, LDH, AST, ALT, C-RP levels were performed. Using a mathematical formula for hydration the POsm levels of the athletes were calculated. [Results] The wrestlers were divided into two groups based on hydration status. There were significant correlations between hydration indicators of Na(+), BUN and PBWL values. There were significant differences between AST, LDH, CK values and skeletal muscle damage indicators of the two groups, but there were no significant differences between the inflammation levels and C-RP values of the groups. [Conclusion] No differences existed in inflammation levels among the wrestlers, although dehydrated wrestlers suffered from higher level of skeletal muscle damage than wrestlers who were not dehydrated.
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Affiliation(s)
- Isik Ozkan
- School of Physical Education and Sports, Afyon Kocatepe
University, Turkey
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14
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Affiliation(s)
| | | | - T. Bond
- Tea Advisory Panel London UK
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15
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Maciejczyk M, Szymanik W. The effect of body fluid balance on cycling peak power. Sci Sports 2014. [DOI: 10.1016/j.scispo.2014.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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16
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Salgado JVV, Lollo PCB, Amaya-Farfan J, Chacon-Mikahil MP. Dietary supplement usage and motivation in Brazilian road runners. J Int Soc Sports Nutr 2014; 11:41. [PMID: 25302054 PMCID: PMC4190927 DOI: 10.1186/s12970-014-0041-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 07/30/2014] [Indexed: 11/21/2022] Open
Abstract
Background The consumption of dietary supplements is highest among athletes and it can represent potential a health risk for consumers. Objective The aim of this study was to determine the prevalence of consumption of dietary supplements by road runners. Methods We interviewed 817 volunteers from four road races in the Brazilian running calendar. The sample consisted of 671 male and 146 female runners with a mean age of 37.9 ± 12.4 years. Results Of the sample, 28.33% reported having used some type of dietary supplement. The main motivation for this consumption is to increase in stamina and improve performance. The probability of consuming dietary supplements increased 4.67 times when the runners were guided by coaches. The consumption of supplements was strongly correlated (r = 0.97) with weekly running distance, and also highly correlated (r = 0.86) with the number of years the sport had been practiced. The longer the runner had practiced the sport, the higher the training volume and the greater the intake of supplements. The five most frequently cited reasons for consumption were: energy enhancement (29.5%), performance improvement (17.1%), increased level of endurance (10.3%), nutrient replacement (11.1%), and avoidance of fatigue (10.3%). About 30% of the consumers declared more than one reason for taking dietary supplements. The most consumed supplements were: carbohydrates (52.17%), vitamins (28.70%), and proteins (13.48%). Conclusions Supplement consumption by road runners in Brazil appeared to be guided by the energy boosting properties of the supplement, the influence of coaches, and the experience of the user. The amount of supplement intake seemed to be lower among road runners than for athletes of other sports. We recommend that coaches and nutritionists emphasise that a balanced diet can meet the needs of physically active people.
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Affiliation(s)
- José Vítor Vieira Salgado
- Exercise Physiology Laboratory - FISEX, FEF-UNICAMP Cidade Universitária, Physical Education Faculty, State University of Campinas, Cep:13083-851, Campinas SP 6134, Brazil ; Sport's Sciences Department, University of Campinas, Physical Education Faculty, Erico Veríssimo Av., 701., Campinas, Brazil
| | - Pablo Christiano Barboza Lollo
- Food's Engineering Faculty, Department of Food and Nutrition, State University of Campinas - UNICAMP, Campinas, SP, Brazil
| | - Jaime Amaya-Farfan
- Food's Engineering Faculty, Department of Food and Nutrition, State University of Campinas - UNICAMP, Campinas, SP, Brazil
| | - Mara PatríciaTraina Chacon-Mikahil
- Exercise Physiology Laboratory - FISEX, FEF-UNICAMP Cidade Universitária, Physical Education Faculty, State University of Campinas, Cep:13083-851, Campinas SP 6134, Brazil
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17
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Hartley NA, Thibeault SL. Systemic hydration: relating science to clinical practice in vocal health. J Voice 2014; 28:652.e1-652.e20. [PMID: 24880674 DOI: 10.1016/j.jvoice.2014.01.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 01/14/2014] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To examine the current state of the science regarding the role of systemic hydration in vocal function and health. STUDY DESIGN Literature review. METHODS Literature search spanning multiple disciplines, including speech-language pathology, nutrition and dietetics, medicine, sports and exercise science, physiology, and biomechanics. RESULTS The relationship between hydration and physical function is an area of common interest among multiple professions. Each discipline provides valuable insight into the connection between performance and water balance, as well as complimentary methods of investigation. Existing voice literature suggests a relationship between hydration and voice production; however, the underlying mechanisms are not yet defined and a treatment effect for systemic hydration remains to be demonstrated. Literature from other disciplines sheds light on methodological shortcomings and, in some cases, offers an alternative explanation for observed phenomena. CONCLUSIONS A growing body of literature in the field of voice science is documenting a relationship between hydration and vocal function; however, greater understanding is required to guide best practice in the maintenance of vocal health and management of voice disorders. Integration of knowledge and technical expertise from multiple disciplines facilitates analysis of existing literature and provides guidance as to future research.
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Affiliation(s)
- Naomi A Hartley
- Division of Otolaryngology, Head and Neck Surgery, Department of Surgery, University of Wisconsin-Madison, Wisconsin Institutes of Medical Research, Madison, Wisconsin
| | - Susan L Thibeault
- Division of Otolaryngology, Head and Neck Surgery, Department of Surgery, University of Wisconsin-Madison, Wisconsin Institutes of Medical Research, Madison, Wisconsin.
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18
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Fleming J, James LJ. Repeated familiarisation with hypohydration attenuates the performance decrement caused by hypohydration during treadmill running. Appl Physiol Nutr Metab 2014; 39:124-9. [DOI: 10.1139/apnm-2013-0044] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study examined the effect of repeated familiarisation to hypohydration on hypohydrated exercise performance. After familiarisation with the exercise protocol, 10 recreationally active males completed a euhydrated (EU-pre) and hypohydrated (HYPO-pre) trial, which involved a 45-min steady state run at 75% peak oxygen uptake (45SS) followed by a 5-km time trial (TT). Euhydration and hypohydration were induced by manipulating fluid intake in the 24-h pre-exercise and during the 45SS. Subjects then completed 4 habituation sessions that involved replication of the HYPO-pre trial, except they completed 60 min of running at 75% peak oxygen uptake and no TT. Subjects then replicated the euhydrated (EU-post) and hypohydrated (HYPO-post) trials. Body mass loss pre-TT was 0.2 (0.2)% (EU-pre), 2.4 (0.3)% (HYPO-pre), 0.1 (0.1)% (EU-post), and 2.4 (0.3)% (HYPO-post). TT performance was 5.8 (2.4)% slower during the HYPO-pre trial (1459 (250) s) than during the EU-pre trial (1381 (237) s) (p < 0.01), but only 1.2 (1.6)% slower during the HYPO-post trial (1381 (200) s) than during the EU-post trial (1366 (211) s) (p = 0.064). TT performance was not different between EU-pre and EU-post trials, but was 5.1 (2.3)% faster during the HYPO-post trial than the HYPO-pre trial (p < 0.01). Heart rate was greater during HYPO trials than EU trials (p < 0.001), whilst rating of perceived exertion (RPE) response was similar to TT time and was lower in the HYPO-post trial than the HYPO-pre trial (p < 0.01). In conclusion, hypohydration impaired 5-km running performance in subjects unfamiliar with the hypohydration protocol, but 4 familiarisation sessions designed to habituate subjects with the hypohydration protocol attenuated the performance decrement, seemingly via an attenuation of RPE during hypohydrated exercise.
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Affiliation(s)
- Joseph Fleming
- SHAPE Research Group, School of Science and Technology, Nottingham Trent University, Nottingham, UK
| | - Lewis J. James
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
- SHAPE Research Group, School of Science and Technology, Nottingham Trent University, Nottingham, UK
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Zoorob R, Parrish MEE, O'Hara H, Kalliny M. Sports nutrition needs: before, during, and after exercise. Prim Care 2013; 40:475-86. [PMID: 23668654 DOI: 10.1016/j.pop.2013.02.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This article discusses how athletes should properly fuel their bodies before, during, and after exercise to maximize athletic performance. Emphasis is placed on hydration status and glycogen stores being maintained above deficits that negatively affect sport performance. Timing of nutrient intake is as important as composition.
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Affiliation(s)
- Roger Zoorob
- Department of Family and Community Medicine, Meharry Medical College, Nashville, TN 37208, USA.
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FORTES MATTHEWB, DIMENT BETHANYC, DI FELICE UMBERTO, GUNN ADRIANE, KENDALL JOEL, ESMAEELPOUR MARIEH, WALSH NEILP. Tear Fluid Osmolarity as a Potential Marker of Hydration Status. Med Sci Sports Exerc 2011; 43:1590-7. [DOI: 10.1249/mss.0b013e31820e7cb6] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Jéquier E, Constant F. Water as an essential nutriment: the physiological basis of hydration. Eur J Clin Nutr 2011. [DOI: 10.1038/ejcn.2011.41] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Prevalence of geriatric conditions: A hospital-wide survey of 455 geriatric inpatients in a tertiary medical center. Arch Gerontol Geriatr 2011; 53:46-50. [DOI: 10.1016/j.archger.2010.06.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 05/31/2010] [Accepted: 06/01/2010] [Indexed: 12/12/2022]
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Logan-Sprenger HM, Palmer MS, Spriet LL. Estimated fluid and sodium balance and drink preferences in elite male junior players during an ice hockey game. Appl Physiol Nutr Metab 2011; 36:145-52. [DOI: 10.1139/h10-098] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Research in many sports suggests that losing ∼2% of body mass (BM) through sweating impairs athletic performance, although this has not been tested in ice hockey players. This study investigated pregame hydration, and on-ice sweat loss, fluid intake, and sodium (Na+) balance of elite male junior players during an ice hockey game. Twenty-four players (2 goalies, 7 defensemen, 15 forwards) volunteered to participate in the study (age, 18.3 ± 0.3 years; weight, 86.5 ±1.6 kg; height, 184.1 ± 1.3 cm). Players were weighed pre- and postgame, fluid and sodium intake were monitored throughout the game, and fluid and Na+ balance were determined within the time between BM measurements. Sweat Na+ loss was calculated based on sweat loss and sweat [Na+] determined from sweat-patch analysis on the same players during an intense practice. Players arrived at the rink in a euhydrated state and drank 0.6 ± 0.1 L of fluid before the game. Mean playing time for the forwards was 18:85 ± 1:15 min:s and playing time for the defense was 24:00 ± 2:46 min:s. Sweat loss was 3.2 ± 0.2 L and exceeded net fluid intake (2.1 ± 0.1 L). Mean BM loss was 1.3% ± 0.3%, with 8/24 players losing between 1.8% to 4.3% BM. Players preferred to drink water and a carbohydrate electrolyte solution before the game and during intermissions, while only water was consumed during each period. Practice mean forehead sweat [Na+] was 74 mmol·L–1. Estimated sweat Na+ losses of 3.1 ± 0.4 g (∼8 g NaCl) coupled with low Na+ intake of 0.8 ± 0.2 g (∼2 g NaCl) resulted in a significant Na+ deficit by the end of the game. This study demonstrated that despite abundant opportunities to hydrate during a hockey game, one-third of the players did not drink enough fluid to prevent sweat losses of 2% BM or higher. Losing 2% BM has been associated with decreases in athletic performance.
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Affiliation(s)
- Heather M. Logan-Sprenger
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Matthew S. Palmer
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Lawrence L. Spriet
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
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24
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25
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The effects of progressive dehydration on strength and power: is there a dose response? Eur J Appl Physiol 2009; 108:701-7. [DOI: 10.1007/s00421-009-1288-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/27/2009] [Indexed: 01/08/2023]
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Abstract
How much water we really need depends on water functions and the mechanisms of daily water balance regulation. The aim of this review is to describe the physiology of water balance and consequently to highlight the new recommendations with regard to water requirements. Water has numerous roles in the human body. It acts as a building material; as a solvent, reaction medium and reactant; as a carrier for nutrients and waste products; in thermoregulation; and as a lubricant and shock absorber. The regulation of water balance is very precise, as a loss of 1% of body water is usually compensated within 24 h. Both water intake and water losses are controlled to reach water balance. Minute changes in plasma osmolarity are the main factors that trigger these homeostatic mechanisms. Healthy adults regulate water balance with precision, but young infants and elderly people are at greater risk of dehydration. Dehydration can affect consciousness and can induce speech incoherence, extremity weakness, hypotonia of ocular globes, orthostatic hypotension and tachycardia. Human water requirements are not based on a minimal intake because it might lead to a water deficit due to numerous factors that modify water needs (climate, physical activity, diet and so on). Water needs are based on experimentally derived intake levels that are expected to meet the nutritional adequacy of a healthy population. The regulation of water balance is essential for the maintenance of health and life. On an average, a sedentary adult should drink 1.5 l of water per day, as water is the only liquid nutrient that is really essential for body hydration.
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Seasonal Changes of Body Mass, Body Composition, and Muscular Performance in Collegiate Wrestlers. Int J Sports Physiol Perform 2008; 3:176-84. [DOI: 10.1123/ijspp.3.2.176] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Purpose:The purpose of the present investigation was to examine the physiological response of collegiate wrestlers to their competitive season.Methods:Eleven Division I collegiate wrestlers (mean ± SD; 19.45 ± 1.13 y) volunteered and completed 4 testing sessions throughout the course of the collegiate wrestling season. Testing sessions were conducted pre-, mid-, and postseason, as well as before the national tournament. Testing consisted of weigh-in, skinfold body composition testing, and a 50-rep concentric, isokinetic leg extension muscle endurance test (180°/s). Muscular performance variables measured included peak torque, peak torque at fatigue, percent decline, and peak torque/body mass ratio.Results:A significant increase (P < .05) of 2.9% was observed for body mass between midseason and postseason (2.38 kg). From pre- to postseason, a mean increase of 3.8% (3.1 kg) was observed for body mass. An increase (P < .05) in BF% of 2.9% was observed between prenationals and postseason. No significant differences (P > .05) were observed between consecutive time points for quadriceps peak torque; however, there was a significant increase (P < .05) between preseason and prenationals (23.39 N·m). Peak torque at fatigue was greater (P < .05) at midseason than preseason, representing an increase of 9.82 N·m. Between midseason and prenationals testing, we observed an 11% increase (P < .05) in %DCLN. Finally, we noted an increase (P < .05) from 0.6 to 0.69 in peak torque/body mass ratio between preseason and prenationals.Conclusions:Our results indicate that while force values seem to suffer at midseason, the wrestlers compensated and were strongest just before their national competition.
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Judelson DA, Maresh CM, Anderson JM, Armstrong LE, Casa DJ, Kraemer WJ, Volek JS. Hydration and Muscular Performance. Sports Med 2007; 37:907-21. [PMID: 17887814 DOI: 10.2165/00007256-200737100-00006] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Significant scientific evidence documents the deleterious effects of hypohydration (reduced total body water) on endurance exercise performance; however, the influence of hypohydration on muscular strength, power and high-intensity endurance (maximal activities lasting >30 seconds but <2 minutes) is poorly understood due to the inconsistent results produced by previous investigations. Several subtle methodological choices that exacerbate or attenuate the apparent effects of hypohydration explain much of this variability. After accounting for these factors, hypohydration appears to consistently attenuate strength (by approximately 2%), power (by approximately 3%) and high-intensity endurance (by approximately 10%), suggesting alterations in total body water affect some aspect of force generation. Unfortunately, the relationships between performance decrement and crucial variables such as mode, degree and rate of water loss remain unclear due to a lack of suitably uninfluenced data. The physiological demands of strength, power and high-intensity endurance couple with a lack of scientific support to argue against previous hypotheses that suggest alterations in cardiovascular, metabolic and/or buffering function represent the performance-reducing mechanism of hypohydration. On the other hand, hypohydration might directly affect some component of the neuromuscular system, but this possibility awaits thorough evaluation. A critical review of the available literature suggests hypohydration limits strength, power and high-intensity endurance and, therefore, is an important factor to consider when attempting to maximise muscular performance in athletic, military and industrial settings.
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Affiliation(s)
- Daniel A Judelson
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, Connecticut, USA.
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Stover EA, Petrie HJ, Passe D, Horswill CA, Murray B, Wildman R. Urine specific gravity in exercisers prior to physical training. Appl Physiol Nutr Metab 2006; 31:320-7. [PMID: 16770361 DOI: 10.1139/h06-004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Urine specific gravity (USG) is used as an index of hydration status. Many studies have used USG to estimate pre-exercise hydration in athletes. However, very little is known about the pre-exercise hydration status of recreational exercisers. The purpose of the present study was to measure the pre-exercise USG in a large sample of recreational exercisers who attended 2 different fitness centers in the United States. In addition, we wanted to determine if factors such as time of day, geographic location, and gender influenced USG. We tested 166 subjects in Chicago and 163 subjects in Los Angeles. Subjects completed a survey on their typical training regimen and fluid-replacement habits, and thereafter voided and delivered a urine sample to the investigators prior to beginning exercise. Samples were measured on site for USG using a hand-held refractometer. The mean (SD) USG was 1.018 (+/- 0.007) for all subjects. Males had a higher average USG (1.020 +/- 0.007) when compared with females (1.017 +/- 0.008; p = 0.001). Despite differences in climate, no difference in mean USG occurred based on location or time of day. Based on standards used for athletes (USG > or = 1.020), 46% of the exercisers were likely to be dehydrated.
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