Effects of an Active Lifestyle on Water Balance

Water is the most abundant chemical constituent of the human body, typically making up approximately two thirds of body mass, but body water content is maintained within relatively narrow limits by a number of regulatory mechanisms. Both a reduction (hypohydration) and increase (hyperhydration) in body water may, if sufficiently severe, lead to adverse health and performance consequences. Active lifestyles, warm climates, and high altitude, as well as some infectious illnesses, increase the likelihood of becoming hypohydrated due to an increase in water loss. Moderate reductions in body water result in changes in cardiovascular system function as well as altering cognitive function and mood. A significant number of elite athletes, recreational exercisers and those with active occupations begin their daily activities in a hypohydrated state and incur large sweat losses during periods of activity, and thus risk negative effects on physiological function. Sweat rate and fluid intake during physical exertion are highly variable between individuals suggesting that an individual hydration strategy may be necessary to avoid significant levels of hypohydration. Rehydration after the completion of physical activity may also be necessary to avoid starting further bouts of activity in a hypohydrated state. Undertaking physical activity in a hypohydrated state appears to increase an individual’s perceived exertion which may negatively influence exercise performance and self-selected exercise intensity, and may decrease the likelihood of further participation in physical activity. This is, therefore, an important consideration for public health as well as competitive sportspeople, be they elite or otherwise. Certain populations, such as the elderly, are more likely to become hypohydrated which may lead to other illnesses and contribute to morbidity and mortality

The Effect of Exercise Intensity on Subsequent Gastric Emptying Rate in Humans.

Previous investigations have suggested that exercise at intensities greater than 70% VO2max reduces gastric emptying rate during exercise, but little is known about the effect of exercise intensity on gastric emptying in the post-exercise period. To examine this, eight healthy subjects completed three experimental trials that included 30 minutes of rest (R), low intensity (L; 33% of peak power output) or high intensity (H; 10 x 1 min at peak power output followed by 2 min rest) exercise. 30 minutes after completion of exercise, participants ingested 595 mL of a 5% glucose solution and gastric emptying rate was assessed via the double sampling gastric aspiration method for 60 minutes. No differences (P > 0.05) were observed in emptying characteristics for total stomach volume or test meal volume between the trials and the quantity of glucose delivered to the intestine was not different between trials (P > 0.05). Half emptying times (Thalf) were not different (P = 0.902) between trials and amounted to (mean ± SD) 22 ± 9, 22 ± 9 and 22 ± 7 minutes during trial R, L and H respectively. These results suggest that exercise has little effect on post-exercise gastric emptying rate of a glucose solution

Practical nutritional recovery strategies for elite soccer players when limited time separates repeated matches

Specific guidelines that aim to facilitate the recovery of soccer players from the demands of training and a congested fixture schedule are lacking; especially in relation to evidence-based nutritional recommendations. The importance of repeated high level performance and injury avoidance while addressing the challenges of fixture scheduling, travel to away venues, and training commitments requires a strategic and practically feasible method of implementing specific nutritional strategies. Here we present evidence-based guidelines regarding nutritional recovery strategies within the context of soccer. An emphasis is placed on providing practically applicable guidelines for facilitation of recovery when multiple matches are played within a short period of time (i.e. 48 h). Following match-play, the restoration of liver and muscle glycogen stores (via consumption of ~1.2 gkg-1h-1 of carbohydrate) and augmentation of protein synthesis (via ~40 g of protein) should be prioritised in the first 20 minutes of recovery. Daily intakes of 6-10 gkg-1 body mass of carbohydrate are recommended when limited time separates repeated matches while daily protein intakes of >1.5 gkg-1 body mass should be targeted; possibly in the form of multiple smaller feedings (e.g., 6 x 20-40 g). At least 150% of the body mass lost during exercise should be consumed within 1 h and electrolytes added such that fluid losses are ameliorated. Strategic use of protein, leucine, creatine, polyphenols and omega-3 supplements could also offer practical means of enhancing post-match recovery. Keywords: soccer, nutrition, recovery, polyphenols, omega-3, creatine, fixture, congestio

Milk: the new sports drink? A Review

There has been growing interest in the potential use of bovine milk as an exercise beverage, especially during recovery from resistance training and endurance sports. Based on the limited research, milk appears to be an effective post-resistance exercise beverage that results in favourable acute alterations in protein metabolism. Milk consumption acutely increases muscle protein synthesis, leading to an improved net muscle protein balance. Furthermore, when post-exercise milk consumption is combined with resistance training (12 weeks minimum), greater increases in muscle hypertrophy and lean mass have been observed. Although research with milk is limited, there is some evidence to suggest that milk may be an effective post-exercise beverage for endurance activities. Low-fat milk has been shown to be as effective, if not more effective, than commercially available sports drinks as a rehydration beverage. Milk represents a more nutrient dense beverage choice for individuals who partake in strength and endurance activities, compared to traditional sports drinks. Bovine low-fat fluid milk is a safe and effective post exercise beverage for most individuals, except for those who are lactose intolerant. Further research is warranted to better delineate the possible applications and efficacy of bovine milk in the field of sports nutrition

Effects of a moderate intake of beer on markers of hydration after exercise in the heat: a crossover study

Background: Exercise in the heat causes important water and electrolytes losses through perspiration. Optimal rehydration is crucial to facilitate the recuperation process after exercise. The aim of our study was to examine whether a moderate beer intake as part of the rehydration has any negative effect protocol after a short but dehydrating bout of exercise in the heat.Methods: Sixteen active male (VO2max, 56 ± 4 mL/kg/min), were included in a crossover study and performed a dehydrating exercise (≤1 h running, 60 %VO2max) twice and 3 weeks apart, in a hot laboratory setting (35 ± 1 °C, humidity 60 ± 2 %). During the two hours following the exercise bouts participants consumed either mineral water ad-libitum (W) or up to 660 ml regular beer followed by water ad-libitum (BW). Body composition, hematological and serum parameters, fluid balance and urine excretion were assessed before, after exercise and after rehydration.Results: Body mass (BM) decreased (both ~ 2.4 %) after exercise in both trials. After rehydration, BM and fat free mass significantly increased although BM did not return to baseline levels (BM, 72.6 ± 6.7 to 73.6 ± 6.9; fat free mass, 56.9 ± 4.7 to 57.5 ± 4.5, no differences BW vs W). Beer intake did not adversely affect any measured parameter. Fluid balance and urine excretion values did not differ between the rehydration strategies.Conclusions: After exercise and subsequent water losses, a moderate beer (regular) intake has no deleterious effects on markers of hydration in active individuals.This study was partially supported by the “Centro de Información Cerveza y Salud” (n° C-2534-00)

Normative data on regional sweat-sodium concentrations of professional male team-sport athletes

Background: The purpose of this paper was to report normative data on regional sweat sweat-sodium concentrations of various professional male team-sport athletes, and to compare sweat-sodium concentrations among sports. Data to this effect would inform our understanding of athlete sodium requirements, thus allowing for the individualisation of sodium replacement strategies. Accordingly, data from 696 athletes (Soccer, n = 270; Rugby, n = 181; Baseball, n = 133; American Football, n = 60; Basketball, n = 52) were compiled for a retrospective analysis. Regional sweat-sodium concentrations were collected using the pilocarpine iontophoresis method, and compared to self-reported measures collected via questionnaire. Results: Sweat-sodium concentrations were significantly higher (p < 0.05) in American football (50.4 ± 15.3 mmol·L-1), baseball (54.0 ± 14.0 mmol·L-1), and basketball (48.3 ± 14.0 mmol·L-1) than either soccer (43.2 ± 12.0 mmol·L-1) or rugby (44.0 ± 12.1 mmol·L-1), but with no differences among the N.American or British sports. There were strong positive correlations between sweat-sodium concentrations and self-reported sodium losses in American football (rs = 0.962, p < 0.001), basketball (rs = 0.953, p < 0.001), rugby (rs = 0.813, p < 0.001), and soccer (rs = 0.748, p < 0.001). Conclusions: The normative data provided on sweat-sodium concentrations might assist sports science/medicine practitioners in generating bespoke hydration and electrolyte-replacement strategies to meet the sodium demands of professional team-sport athletes. Moreover, these novel data suggest that self-reported measures of sodium loss might serve as an effective surrogate in the absence of direct measures; i.e., those which are more expensive or non-readily available

Influence of daily beer or ethanol consumption on physical fitness in response to a high-intensity interval training program. The BEER-HIIT study

The authors would like to thank all the participants that took part of the study for their time and effort. We are grateful to Ms. Ana Yara PostigoFuentes for her assistance with the English language. This study is part of Cristina Molina-Hidalgo’s Doctoral Thesis conducted in the Official Doctoral Programme in Psychology of the University of Granada, Spain.Background: High-intensity interval training (HIIT) is an effective approach to improve physical fitness, but consuming beer, which is a regular practice in many physically active individuals, may interfere with these effects. The purposes of this study were to investigate the effects of a 10-week (2 days/week) HIIT program on cardiorespiratory fitness, muscle strength and power parameters, and also to assess the possible influence on them of a moderate consumption of beer (at least from Monday to Friday) or its alcohol equivalent. Methods: Young (24 ± 6 years old) healthy adults (n = 73, 35 females) were allocated to five groups. Four groups participated in the HIIT intervention program while the fifth group was a control Non-Training group (n = 15). Participants in the training groups chose whether they preferred receiving alcohol or alcohol-free beverages. Those choosing alcohol were randomized to either beer or ethanol intake: (i) T-Beer group (alcohol beer, 5.4%; n = 13) or (ii) T-Ethanol (sparkling water with vodka, 5.4%; n = 14). Those choosing alcohol-free intake were randomized to (iii) T-Water group (sparkling water, 0.0%; n = 16), or (iv) T-0.0Beer group (alcohol-free beer, 0.0%; n = 15). Men ingested 330 ml of the beverage at lunch and 330 ml at dinner; women ingested 330 ml at dinner. Before and after the intervention, maximal oxygen uptake in absolute and relative terms (VO2max.), maximal heart rate, total test duration, hand grip strength and four types of vertical jumps were measured. Results: HIIT induced significant improvements in absolute and relative values of VO2max, and total test duration (all p < 0.05) in all the training groups; also, clinical improvements were found in hand grip strength. These positive effects were not influenced by the regular intake of beer or alcohol. No changes in the vertical jumps occurred in any of the groups. Conclusions: A moderate beer or alcohol intake does not mitigate the positive effect of a 10-week HIIT on physical fitness in young healthy adults. Trial registration: ClinicalTrials.gov ID: NCT03660579. Registered 20 September 2018. Retrospectively registered.Centro de Informacion Cerveza y Salud (CICS), Madrid, SpainSpanish Government FPU14/04172 FPU15/0396

Water and sodium intake habits and status of ultra-endurance runners during a multi-stage ultra-marathon conducted in a hot ambient environment: an observational field based study

<p>Abstract</p> <p>Background</p> <p>Anecdotal evidence suggests ultra-runners may not be consuming sufficient water through foods and fluids to maintenance euhydration, and present sub-optimal sodium intakes, throughout multi-stage ultra-marathon (MSUM) competitions in the heat. Subsequently, the aims were primarily to assess water and sodium intake habits of recreational ultra-runners during a five stage 225 km semi self-sufficient MSUM conducted in a hot ambient environment (T_max range: 32°C to 40°C); simultaneously to monitor serum sodium concentration, and hydration status using multiple hydration assessment techniques.</p> <p>Methods</p> <p>Total daily, pre-stage, during running, and post-stage water and sodium ingestion of ultra-endurance runners (UER, <it>n</it> = 74) and control (CON, <it>n</it> = 12) through foods and fluids were recorded on Stages 1 to 4 by trained dietetic researchers using dietary recall interview technique, and analysed through dietary analysis software. Body mass (BM), hydration status, and serum sodium concentration were determined pre- and post-Stages 1 to 5.</p> <p>Results</p> <p>Water (overall mean (SD): total daily 7.7 (1.5) L/day, during running 732 (183) ml/h) and sodium (total daily 3.9 (1.3) g/day, during running 270 (151) mg/L) ingestion did not differ between stages in UER (<it>p</it> < 0.001 <it>vs</it>. CON). Exercise-induced BM loss was 2.4 (1.2)% (<it>p</it> < 0.001). Pre- to post-stage BM gains were observed in 26% of UER along competition. Pre- and post-stage plasma osmolality remained within normal clinical reference range (280 to 303 mOsmol/kg) in the majority of UER (<it>p</it> > 0.05 <it>vs</it>. CON pre-stage). Asymptomatic hyponatraemia (<135 mmol/L) was evident pre- and post-stage in <it>n</it> = 8 UER, corresponding to 42% of sampled participants. Pre- and post-stage urine colour, urine osmolality and urine/plasma osmolality ratio increased (<it>p</it> < 0.001) as competition progressed in UER, with no change in CON. Plasma volume and extra-cellular water increased (<it>p</it> < 0.001) 22.8% and 9.2%, respectively, from pre-Stage 1 to 5 in UER, with no change in CON.</p> <p>Conclusion</p> <p>Water intake habits of ultra-runners during MSUM conducted in hot ambient conditions appear to be sufficient to maintain baseline euhydration levels. However, fluid over-consumption behaviours were evident along competition, irrespective of running speed and gender. Normonatraemia was observed in the majority of ultra-runners throughout MSUM, despite sodium ingestion under benchmark recommendations.</p