Hydration in sport and exercise: water, sports drinks and other drinks

Compositional Aspects of Beverages Designed to Promote Hydration Before, During, and After Exercise: Concepts Revisited

Hypohydration can impair aerobic performance and deteriorate cognitive function during exercise. To minimize hypohydration, athletes are recommended to commence exercise at least euhydrated, ingest fluids containing sodium during long-duration and/or high-intensity exercise to prevent body mass loss over 2% and maintain elevated plasma osmolality, and rapidly restore and retain fluid and electrolyte homeostasis before a second exercise session. To achieve these goals, the compositions of the fluids consumed are key; however, it remains unclear what can be considered an optimal formulation for a hydration beverage in different settings. While carbohydrate-electrolyte solutions such as sports drinks have been extensively explored as a source of carbohydrates to meet fuel demands during intense and long-duration exercise, these formulas might not be ideal in situations where fluid and electrolyte balance is impaired, such as practicing exercise in the heat. Alternately, hypotonic compositions consisting of moderate to high levels of electrolytes (i.e., ≥45 mmol/L), mainly sodium, combined with low amounts of carbohydrates (i.e., <6%) might be useful to accelerate intestinal water absorption, maintain plasma volume and osmolality during exercise, and improve fluid retention during recovery. Future studies should compare hypotonic formulas and sports drinks in different exercise settings, evaluating different levels of sodium and/or other electrolytes, blends of carbohydrates, and novel ingredients for addressing hydration and rehydration before, during, and after exercise.

Athletes Drink Gatorade: DMA Advertising Expenditures, Ad Recall, and Athletic Identity Influence Energy and Sports Drink Consumption

Understanding why sports and energy drinks remain increasingly popular among adolescents despite declines in other sugar sweetened beverages is critical. This study points to memory for advertising exposure and adolescent athletic identity as two aspects that together help to explain consumption. An online survey of U.S. adolescents aged 14-18 (n = 503) was combined with Nielsen data for television and social media advertising expenditures by sports and energy drink brands in participants' designated market areas (DMAs). Advertisement recall mediates the relationship between social media DMA expenditures and sports and energy drink consumption. Recall for television advertisements is related to consumption but is unrelated to television DMA expenditures. Athletic identity moderated the relationship between recall and consumption such that consumption increased as both recall and athletic identity increased, suggesting a role for motivated memory and motivated processing of ad messages based on athletic identity consistent with the limited capacity model of motivated media message processing. Based on these results, we conclude that effectiveness of expenditures in influencing behavior is dependent upon both ad recall and ad relevance, and that athletic identity is an important factor in ad effectiveness in the context of sports and energy drinks advertising.

Origins of thirstiness sensation and current food solutions

The sensation of thirstiness is the desire to drink water. In certain situations, the ingestion of liquid water can be restricted. As a result, thirstiness is not relieved, resulting in an uncomfortable and distressing situation. The present review describes thirstiness and hydration, the food products and beverages that cause thirstiness, and the beverages and food products currently available to quench thirstiness in individuals with restricted access to liquid ingestion. It also discusses how to measure the effectiveness of calming thirstiness. To diminish thirstiness distress, different alternatives to liquids are proposed. Individuals with swallowing disorders are given thickened water, individuals with restricted water ingestion are given ice cubes or ice popsicles of different flavors, and sportspeople are given energy gels. However, current beverage solutions seem not to relieve thirst fully, although some stimuli like iced water, flavors (especially lemon and mint), or acids seem to work better than plain stimuli and could be added to existing products. Therefore, there is still a need to incorporate these strategies into beverage and food formulations and to test their effectiveness.

Isolate Whey Protein Promotes Fluid Balance and Endurance Capacity Better Than Isolate Casein and Carbohydrate-Electrolyte Solution in a Warm, Humid Environment

Protein ingestion is known to enhance post-exercise hydration. Whether the type of protein (i.e., whey, casein) can alter this response is unknown. Accordingly, this study aimed to compare the effects of the addition of milk-derived whey isolate or casein protein to carbohydrate-electrolyte (CE) drinks on post-exercise rehydration and endurance capacity. Thirty male soldiers (age: 24 ± 2.1 y; VO2max: 49.3 ± 4.7 mL/kg/min) were recruited. Upon losing ~2.2% of body mass by running in warm and humid conditions (32.3 °C, 76% relative humidity [RH]), participants ingested either a CE solution (66 g/L carbohydrate [CHO]), or CE plus isolate whey protein (CEW, 44 g/L CHO, 22 g/L isolate whey), or CE plus isolate casein protein (CEC, 44 g/L CHO, 22 g/L isolate casein) beverage in a volume equal to 150% of body mass loss. At the end of the 3 h rehydration period, a positive fluid balance was higher with CEW (0.22 L) compared to CEC (0.19 L) and CE (0.12 L). Overall mean fluid retention was higher in CEW (80.35%) compared with the CE (76.67%) and CEC trials (78.65%). The time of the endurance capacity test [Cooper 2.4 km (1.5 miles) run test] was significantly higher in CEC (14.25 ± 1.58 min) and CE [(12.90 ± 1.01 min; (p = 0.035)] than in CEW [(11.40 ± 1.41 min); (p = 0.001)]. The findings of this study indicate that the inclusion of isolate whey protein in a CE solution yields superior outcomes in terms of rehydration and enhanced endurance capacity, as compared to consuming the CE solution alone or in conjunction with isolate casein protein.

Functional Beverages in the 21st Century

Underlying the dawn of humanity was primarily the search for food and access to drinking water. Over the course of civilization, there has been a significant increase in drinking water quality. By the average of the nutritional standards, the daily water demand is 2.5 L (also including liquid products such as tea, coffee, or soup). However, it is worth noticing that the need is strictly individual for each person and depends on two major factors, namely, epidemiological (sex, age state of health, lifestyle, and diet) and environmental (humidity and air temperature). Currently, our diet is more and more often enriched with isotonic drinks, functional drinks, or drinks bearing the hallmarks of health-promoting products. As a result, manufacturing companies compete to present more interesting beverages with complex compositions. This article will discuss both the composition of functional beverages and their impact on health.

A Survey of Combat Athletes' Rapid Weight Loss Practices and Evaluation of the Relationship With Concussion Symptom Recall

OBJECTIVE

There is a high incidence of concussion and frequent utilization of rapid weight loss (RWL) methods among combat sport athletes, yet the apparent similarity in symptoms experienced as a result of a concussion or RWL has not been investigated. This study surveyed combat sports athletes to investigate the differences in symptom onset and recovery between combat sports and evaluated the relationships between concussion and RWL symptoms.

DESIGN

Cross-sectional study.

SETTING

Data were collected through an online survey.

PARTICIPANTS

One hundred thirty-two (115 male athletes and 17 female athletes) combat sport athletes.

INTERVENTIONS

Modified Sport Concussion Assessment Tool (SCAT) symptom checklist and weight-cutting questionnaire.

MAIN OUTCOME MEASURES

Survey items included combat sport discipline, weight loss, medical history, weight-cutting questionnaire, and concussion and weight-cutting symptom checklists.

RESULTS

Strong associations ( rs = 0.6-0.7, P < 0.05) were observed between concussion and RWL symptoms. The most frequently reported symptom resolution times were 24 to 48 hours for a weight cut (WC; 59%) and 3 to 5 days for a concussion (43%), with 60% to 70% of athletes reporting a deterioration and lengthening of concussion symptoms when undergoing a WC. Most of the athletes (65%) also reported at least one WC in their career to " not go according to plan ," resulting in a lack of energy (83%) and strength/power (70%).

CONCLUSIONS

Rapid weight loss and concussion symptoms are strongly associated, with most of the athletes reporting a deterioration of concussion symptoms during a WC. The results indicate that concussion symptoms should be monitored alongside hydration status to avoid any compound effects of prior RWL on the interpretation of concussion assessments and to avoid potential misdiagnoses among combat athletes.

Comparison of hydration efficacy of carbohydrate-electrolytes beverages consisting of isomaltulose and sucrose in healthy young adults: A randomized crossover trial

Isomaltulose is a low glycemic and insulinaemic carbohydrate now used as an alternative sweetener in beverages. However, it remains unclear if hydration status may be impacted differently with the consumption of beverages containing isomaltulose as compared to sucrose, a common beverage sweetener. Thirteen young adults (7 women) consumed 1 L of a carbohydrate beverage (with low electrolyte content) containing either 6.5%-sucrose, 6.5%-isomaltulose, or water within a 15 min period. For each beverage, beverage hydration index (BHI, a composite measure of fluid balance after consuming a test beverage relative to water) was calculated from urine volume produced over a 3 h period following ingestion of the carbohydrate beverages relative to water. The change in plasma volume (ΔPV), blood glucose, and lactate concentrations were assessed every 30 min post-beverage consumption. Isomaltulose ingestion attenuated urine production as compared to water and sucrose (P ≤ 0.005) over the 3 h post-ingestion period. However, no differences were observed between sucrose and water (P = 0.055). BHI was 1.53 ± 0.44 for isomaltulose (P ≤ 0.022 vs. sucrose and water) and 1.20±0.29 for sucrose (P = 0.210 vs. water). A transient reduction in ΔPV was observed following the ingestion of the isomaltulose beverage (at 30 min, P = 0.007 vs. sucrose). Thereafter, no differences in ΔPV between beverages were measured. Increases in blood glucose and lactate, indices of absorption and utility of glucose, were delayed in the isomaltulose as compared to sucrose beverage. In summary, we demonstrated a greater BHI with a carbohydrate-electrolyte beverage containing isomaltulose as compared to sucrose. This may in part be attributed to a delayed absorption of isomaltulose reducing diuresis.

Chia Seeds (Salvia hispanica L.): Can They Be Used as Ingredients in Making Sports Energy Gel?

Dehydration during exercise has been shown to limit performance. This study aimed to determine the best hydrocolloid for producing sports energy gel from chia seeds (Salvia hispanica L.). This study was a completed random-design study using one factor: the addition of 0.1% w/w hydrocolloids (SEG1: xanthan gum; SEG2: pectin; and SEG3: carboxymethyl cellulose). A sports energy gel was then analyzed for pH, viscosity, total soluble solids, potassium content, and gross energy. The sensory characteristics that were analyzed include color, texture, aroma, and flavor, using hedonic tests on 25 panelists. The addition of different hydrocolloids resulted in significant differences in pH, viscosity, total soluble solids, potassium, and energy contents (p = 0.026; 0.0001; 0.0001; and 0.0001). Differences in hydrocolloid types also led to differences in the panelists’ perceptions of the sports energy gels’ colors and textures (p = 0.008 and 0.0001). The best formulation was the sports energy gel with added xanthan gum, which showed the highest average energy, total soluble solids, potassium, and viscosity values, and the lowest average of pH values (60.24 ± 0.340, 10.6 ± 0.08, 19.6 ± 0.23, 367.4 ± 9.81, and 5.2 ± 0.38, respectively). The conclusion is that chia seeds can be used as the main ingredient for producing a high-energy sports gel. Energy has a huge impact on a person’s physical and mental health.

Differential effect of maximal incremental treadmill exercise on tear secretion and tear film stability in athletes and non-athletes

The study investigated the differential response to a single bout of maximal incremental treadmill exercise between athletes and non-athletes without dry eyes regarding tear secretion, tear film stability, visual acuity (VA), and stereoacuity. Additionally, the study examined the effect of gender and the duration of exercise on exercise-induced changes. Study participants included young university students aged 18-25 years who were athletes (male/female: 13/13) or non-athletes (male/female: 17/9). Participants underwent an aerobic exercise session using a treadmill and following the laid down Bruce treadmill test protocol till exhaustion. Measurements were taken in the order of distance VA, stereopsis, non-invasive tear break-up time (TBUT), and phenol red thread test, at baseline and after the exercise regimen. Within- and between-subject analyses using multiple t-tests with correction for multiple comparisons were performed to determine differences before and after exercise in athletes and non-athletes. Subsequently, ANCOVA was used to assess the influence of gender and the duration of exercise. The mean age (SD) of the athletes and the non-athletes was 22.4 ± 2.1 years and 21.8 ± 2.1 years, respectively (p = 0.357). Before exercise, the athletes had higher TBUT than non-athletes (14.6 ± 2.9 s vs. 11.9 ± 3.8 s; p = 0.021), but no difference was observed in any other ocular measurements. After exercise, the athletes showed significant improvement in tear secretion with the basal tear secretion increasing from 22.3 ± 2.5 mm to 25.8 ± 1.7 mm (p < 0.001). The non-athletes on the other hand had a borderline increase in tear secretion from 21.42 ± 2.85 mm to 23.73 ± 2.68 mm (p = 0.08). Also, the TBUT was much improved in the athletes after exercise compared to the non-athletes (17.7 ± 2.7 s vs. 14.8 ± 2.9 s, p = 0.004). Additionally, exercise improved the VA indifferently between the groups, while stereoacuity was unchanged after exercise in either group. Gender had no influence on the differences in the tear function measures between athletes and non-athletes after exercise. The duration of exercise, however, showed a borderline effect on the tear film stability (p = 0.068) after exercise. Our findings support the differential effect of maximal incremental treadmill exercise on tear secretion and tear film stability between athletes and non-athletes. Thus, increased physical fitness and the duration of exercise might be crucial in the improvement of tear function through aerobic exercise.

Hydration Is More Important Than Exogenous Carbohydrate Intake During Push-to-the-Finish Cycle Exercise in the Heat

Dehydration ≥2% loss of body mass is associated with reductions in performance capacity, and carbohydrate (CHO)-electrolyte solutions (CES) are often recommended to prevent dehydration and provide a source of exogenous carbohydrate during exercise. It is also well established that performance capacity in the heat is diminished compared to cooler conditions, a response attributable to greater cardiovascular strain caused by high skin and core temperatures. Because hydration status, environmental conditions, and carbohydrate availability interact to influence performance capacity, we sought to determine how these factors affect push-to-the-finish cycling performance. Ten young trained cyclists exercised at a moderate intensity (2.5 W·kg^-1) in a hot-dry condition [40°C, 20% relative humidity (RH)] until dehydration of ~2% body mass. Subjects then consumed either no fluid (NF) or enough fluid (water, WAT; Gatorade®, GAT; or GoodSport™, GS) to replace 75% of lost body mass over 30 min. After a 30-min light-intensity warm-up (1.5 W·kg^-1) in a 35°C, 20% RH environment, subjects then completed a 120-kJ time trial (TT). TT time-to-completion, absolute power, and relative power were significantly improved in WAT (535 ± 214 s, 259 ± 99 W, 3.3 ± 0.9 W·kg^-1), GAT (539 ± 226 s, 260 ± 110 W, 3.3 ± 1.0 W·kg^-1), and GS (534 ± 238 s, 262 ± 105 W, 3.4 ± 1.0 W·kg^-1) compared to NF (631 ± 310 s, 229 ± 96 W, 3.0 ± 0.9 W·kg^-1) all (p < 0.01) with no differences between WAT, GAT, and GS, suggesting that hydration is more important than carbohydrate availability during exercise in the heat. A subset of four subjects returned to the laboratory to repeat the WAT, GAT, and GS treatments to determine if between-beverage differences in time-trial performance were evident with a longer TT in thermoneutral conditions. Following dehydration, the ambient conditions in the environmental chamber were reduced to 21°C and 20% RH and subjects completed a 250-kJ TT. All four subjects improved TT performance in the GS trial (919 ± 353 s, 300 ± 100 W, 3.61 ± 0.86 W·kg^-1) compared to WAT (960 ± 376 s, 283 ± 91 W, 3.43 ± 0.83 W·kg^-1), while three subjects improved TT performance in the GAT trial (946 ± 365 s, 293 ± 103 W, 3.60 ± 0.97 W·kg^-1) compared to WAT, highlighting the importance of carbohydrate availability in cooler conditions as the length of a push-to-the-finish cycling task increases.

The Impact of Diet and Physical Activity on Bone Health in Children and Adolescents

There is growing recognition of the role of diet and physical activity in modulating bone mineral density, bone mineral content, and remodeling, which in turn can impact bone health later in life. Adequate nutrient composition could influence bone health and help to maximize peak bone mass. Therefore, children's nutrition may have lifelong consequences. Also, physical activity, adequate in volume or intensity, may have positive consequences on bone mineral content and density and may preserve bone loss in adulthood. Most of the literature that exists for children, about diet and physical activity on bone health, has been translated from studies conducted in adults. Thus, there are still many unanswered questions about what type of diet and physical activity may positively influence skeletal development. This review focuses on bone requirements in terms of nutrients and physical activity in childhood and adolescence to promote bone health. It explores the contemporary scientific literature that analyzes the impact of diet together with the typology and timing of physical activity that could be more appropriate depending on whether they are children and adolescents to assure an optimal skeleton formation. A description of the role of parathyroid hormone (PTH) and gut hormones (gastric inhibitory peptide (GIP), glucagon-like peptide (GLP)-1, and GLP-2) as potential candidates in this interaction to promote bone health is also presented.

Comparisons of isomaltulose, sucrose, and mixture of glucose and fructose ingestions on postexercise hydration state in young men

PURPOSE

Isomaltulose is a low glycemic and insulinaemic carbohydrate available as a constituent in sports drink. However, it remains unclear whether postexercise rehydration achieved by isomaltulose drink ingestion alone differs as compared to other carbohydrates.

METHODS

Thirteen young men performed intermittent exercise in the heat (35 °C and relative humidity 40%) to induce a state of hypohydration as defined by a 2% loss in body mass. Thereafter, participants were rehydrated by ingesting drinks equal to the volume of body mass loss with either a mixture of 3.25% glucose and 3.25% fructose, 6.5% sucrose (SUC), or 6.5% isomaltulose (ISO) within the first 30 min of a 3-h recovery. The change in plasma volume (ΔPV) from pre-exercise baseline, blood glucose, and plasma insulin concentration were assessed every 30-min.

RESULTS

ΔPV was lower in ISO as compared to SUC until 90 min of the recovery (all P ≤ 0.038) with no difference thereafter (all P ≥ 0.391). The ΔPV were paralleled by concomitant changes in blood glucose levels that were greater in ISO as compared to other drinks after 90 min of the recovery (all P ≤ 0.035). Plasma insulin secretion, which potentially enhances renal sodium reabsorption and fluid retention, did not differ between the trials (interaction, P = 0.653). ISO induced a greater net fluid volume retention as compared to SUC (P = 0.010).

CONCLUSION

We showed that rehydration with an isomaltulose drink following exercise-heat stress induces comparable recovery of PV and a greater net fluid retention as compared to other drinks, albeit this response is delayed. The delayed water transport along with glucose absorption may modulate this response. This trial was registered in 25th Sep 2019 at https://www.umin.ac.jp/ as UMIN000038099. (249/250).

Dysphagia-Related Health Information Improved Consumer Acceptability of Thickened Beverages

Most people tend to think that healthy foods do not taste good. This view could have a negative impact on the taste of the food that people eat for health. However, if health-related information is provided to avoid negative aspects, acceptability may improve. Thus, this study investigated changes in consumers’ sensory perception of thickened beverages before and after the provision of dysphagia-related health information. Sixty young (19–39 years old) and middle-aged (40–64 years old) consumers participated in two experiment sessions conducted one week apart. The first session proceeded without any information and the second provided information about dysphagia and the need for dietary modification before evaluation. Three beverages (orange juice, red bean water, and sports drink) were used in nectar-like (51–350 cP) and honey-like (351–1750 cP) forms; original beverage samples (0%) were used as the control. Consumers were asked about acceptability, liking the flavor, intensity, and general health interest (GHI). An analysis of variance was performed to show the change in flavor rating and acceptability between the two sessions. Although there were age-related differences in response to the samples, thickened beverages were rated as more acceptable, in terms of their characteristics (swallowing, viscosity, and mouthfeel) after the information was provided. There were no significant differences for the 0% samples. The mean GHI values were 3.97 ± 0.85 and 4.81 ± 0.68 for the young and middle-aged groups, respectively. High and low GHI groups were analyzed. The high GHI group showed significant differences in acceptability in the informed evaluation, whereas the low GHI group was not influenced by the information.

Sodium Ingestion Improves Groundstroke Performance in Nationally-Ranked Tennis Players: A Randomized, Placebo-Controlled Crossover Trial

This study examined the dose-response effects of ingesting different sodium concentrations on markers of hydration and tennis skill. Twelve British nationally-ranked tennis players (age: 21.5 ± 3.1 years; VO_2peak: 45.5 ± 4.4 ml^.kg^.min^-1) completed four identical in-door tennis training sessions in a cluster randomized, single-blind, placebo-controlled, crossover design. Twenty-minutes prior to each training session, participants consumed a 250 ml sodium-containing beverage (10, 20, 50 mmol/L) or a placebo (0 mmol/L), and continued to consume 1,000 ml of the same beverage at set periods during the 1-h training session. Tennis groundstroke and serve performance, agility, urine osmolality, fluid loss, sodium sweat loss and perceptual responses (rating of perceived exertion (RPE), thirst, and gastrointestinal (GI) discomfort) were assessed. Results showed that ingesting 50 mmol/L sodium reduced urine osmolality (-119 mOsmol/kg; p = 0.037) and improved groundstroke performance (5.4; p < 0.001) compared with placebo. This was associated with a reduction in RPE (-0.42; p = 0.029), perception of thirst (-0.58; p = 0.012), and GI discomfort (-0.55; p = 0.019) during the 50 mmol/L trial compared with placebo. Linear trend analysis showed that ingesting greater concentrations of sodium proportionately reduced urine osmolality (β = -147 mOsmol/kg; p = 0.007) and improved groundstroke performance (β = 5.6; p < 0.001) in a dose response manner. Perceived thirst also decreased linearly as sodium concentration increased (β = -0.51; p = 0.044). There was no evidence for an effect of sodium consumption on fluid loss, sweat sodium loss, serve or agility performance (p > 0.05). In conclusion, consuming 50 mmol/L of sodium before and during a 1-h tennis training session reduced urine osmolality and improved groundstroke performance in nationally-ranked tennis players. There was also evidence of dose response effects, showing that ingesting greater sodium concentrations resulted in greater improvements in groundstroke performance. The enhancement in tennis skill may have resulted from an attenuation of symptomologic distracters associated with hypohydration, such as RPE, thirst and GI discomfort.

Effects of isomaltulose ingestion on postexercise hydration state and heat loss responses in young men

NEW FINDINGS

What is the central question of this study? What are the effects of isomaltulose, an ingredient in carbohydrate-electrolyte beverages to maintain glycaemia and attenuate the risk of dehydration during exercise heat stress, on postexercise rehydration and physiological heat loss responses? What is the main finding and its importance? Consumption of a 6.5% isomaltulose-electrolyte beverage following exercise heat stress restored hydration following a 2 h recovery as compared to a 2% solution or water only. While the 6.5% isomaltulose-electrolytes increased plasma volume and plasma osmolality, which are known to modulate postexercise heat loss, sweating and cutaneous vascular responses did not differ between conditions. Consequently, ingestion beverages containing 6.5% isomaltulose-electrolytes enhanced postexercise rehydration without affecting heat loss responses.

ABSTRACT

Isomaltulose is a disaccharide carbohydrate widely used during exercise to maintain glycaemia and hydration. We investigated the effects of ingesting a beverage containing isomaltulose and electrolytes on postexercise hydration state and physiological heat loss responses. In a randomized, single-blind cross-over design, 10 young healthy men were hypohydrated by performing up to three 30 min successive moderate-intensity (50% heart rate reserve) bouts of cycling, each separated by 10 min, while wearing a water-perfusion suit heated to 45°C. The protocol continued until a 2% reduction in body mass was achieved. Thereafter, participants performed a final 15 min moderate-intensity exercise bout followed by a 2 h recovery. Following cessation of exercise, participants ingested a beverage consisting of (i) water only (Water), (ii) 2% isomaltulose (CHO-2%), or (iii) 6.5% isomaltulose (CHO-6.5%) equal to the volume of 2% body mass loss within the first 30 min of the recovery. Changes in plasma volume (ΔPV) after fluid ingestion were greater for CHO-6.5% compared with CHO-2% (120 min postexercise) and Water (90 and 120 min) (all P ≤ 0.040). Plasma osmolality remained elevated with CHO-6.5% compared with consumption of the other beverages at 30 and 90 min postexercise (all P ≤ 0.050). Urine output tended to be reduced with CHO-6.5% compared to other fluid conditions (main effect, P = 0.069). Rectal and mean skin temperatures, chest sweat rate and cutaneous perfusion did not differ between conditions (all P > 0.05). In conclusion, compared with CHO-2% and Water, consuming a beverage consisting of CHO-6.5% and electrolytes during recovery under heat stress enhances PV recovery without modulating physiological heat loss responses.

Effects of whey protein in carbohydrate-electrolyte drinks on post-exercise rehydration

The purpose of this study was to examine the effects of different amounts of whey protein in carbohydrate-electrolyte (CE) drinks on post-exercise rehydration. Ten males completed 5 trials in a randomised cross-over design. A 4-h recovery was applied after a 60-min run at 65% VO_2peak in each trial. During recovery, the participants ingested a high-carbohydrate CE drink (CE-H), a low-carbohydrate CE drink (CE-L), a high-whey-protein (33 g·L^-1) CE drink (CW-H), a medium-whey-protein (22 g·L^-1) CE drink (CW-M) or a low-whey-protein (15 g·L^-1) CE drink (CW-L) in a volume equivalent to 150% of their body mass (BM) loss. The drinks were provided in six equal boluses and consumed by the participants within 150 min in each trial. After exercise, a BM loss of 2.15% ± 0.05% was achieved. Urine production was less in the CW-M and CW-H trials during recovery, which induced a greater fluid retention in the CW-M (51.0% ± 5.7%) and CW-H (55.4% ± 3.8%) trials than in any other trial (p < .05). The plasma albumin content was higher in the CW-H trial than in the CE-H and CE-L trials at 2 h (p < .05) and 3 h (p < .01) during recovery. The aldosterone concentration was lower in the CE-H trial than in the CW-M and CW-H trials after recovery (p < .05). It is concluded that the rehydration was improved when whey protein was co-ingested with CE drinks during a 4-h recovery after a 60-min run. However, this additive effect was only observed when whey protein concentration was at least 22 g·L^-1 in the current study.

Effects of protein addition to carbohydrate-electrolyte solutions on postexercise rehydration

Background/Objective

This study aimed to examine the effects of the addition of whey or casein protein, the two major proteins in milk, to carbohydrate-electrolyte (CE) solutions on postexercise rehydration.

Methods

Ten young men aged 20.7 ± 1.4 years with an average VO_2max of 60.7 mL/kg/min ran for 60 minutes at 65% VO_2max on three occasions followed by 4 hours' recovery. During recovery, the participants consumed either CE solution with 66 g/L carbohydrate (CHO), or CE plus whey protein solution (CW trial, 44 g/L CHO, 22 g/L whey), or CE plus casein protein solution (CC trial, 44 g/L CHO, 22 g/L casein); the solutions were matched for energy and electrolyte content.

Results

The participants lost 2.36 ± 0.32% of their pre-exercise body weight after the exercise. Total urine output after recovery was greater in the CE and CC trials than CW trial (CE vs. CW vs. CC: 1184 ± 378 mL vs. 1005 ± 214 mL vs. 1256 ± 413 mL; p < 0.05). Fluid retention after ingestion of CW solution was greater than CE and CC solutions (CE vs. CW vs. CC: 46.9 ± 16.5% vs. 54.9 ± 9.2% vs. 45.8 ± 17.3%; p < 0.05). Lower urine specific gravity and urine osmolality were observed by the end of recovery in the CE trial compared with CW trial (p < 0.05). No difference was found in the changes in plasma volume in all trials.

Conclusion

These results suggest that during the 4 hours' recovery after a 60-minute run, the CW solution was more effective for rehydration compared with the CE or CC solution.

Evidence-informed physical therapy management of performance-related musculoskeletal disorders in musicians

Playing a musical instrument at an elite level is a highly complex motor skill. The regular daily training loads resulting from practice, rehearsals and performances place great demands on the neuromusculoskeletal systems of the body. As a consequence, performance-related musculoskeletal disorders (PRMDs) are globally recognized as common phenomena amongst professional orchestral musicians. These disorders create a significant financial burden to individuals and orchestras as well as lead to serious consequences to the musicians’ performance and ultimately their career. Physical therapists are experts in treating musculoskeletal injuries and are ideally placed to apply their skills to manage PRMDs in this hyper-functioning population, but there is little available evidence to guide specific injury management approaches. An Australia-wide survey of professional orchestral musicians revealed that the musicians attributed excessively high or sudden increase in playing-load as major contributors to their PRMDs. Therefore, facilitating musicians to better manage these loads should be a cornerstone of physical therapy management. The Sound Practice orchestral musicians work health and safety project used formative and process evaluation approaches to develop evidence-informed and clinically applicable physical therapy interventions, ultimately resulting in favorable outcomes. After these methodologies were employed, the intervention studies were conducted with a national cohort of professional musicians including: health education, onsite injury management, cross-training exercise regimes, performance postural analysis, and music performance biomechanics feedback. The outcomes of all these interventions will be discussed alongside a focussed review on the existing literature of these management strategies. Finally, a framework for best-practice physical therapy management of PRMDs in musicians will be provided.

New isotonic drinks with antioxidant and biological capacities from berries (maqui, açaí and blackthorn) and lemon juice

The aim of the study was to design new isotonic drinks with lemon juice and berries: maqui [Aristotelia chilensis (Molina) Stuntz], açaí (Euterpe oleracea Mart.) and blackthorn (Prunus spinosa L.), following on from previous research. Quality parameters - including colour (CIELab parameters), minerals, phytochemical identification and quantification by high-performance liquid chromatography with diode array detector, total phenolic content by the Folin-Ciocalteu reagent, the antioxidant capacity (ABTS(+), DPPH• and [Formula: see text] assays) and biological activities (in vitro alpha-glucosidase and lipase inhibitory effects) - were tested in the samples and compared to commercially available isotonic drinks. The new isotonic blends with lemon and anthocyanins-rich berries showed an attractive colour, especially in maqui samples, which is essential for consumer acceptance. Significantly higher antioxidant and biological effects were determined in the new blends, in comparison with the commercial isotonic beverages.