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Susan M. Shirreffs, Luis F. Aragon-Vargas, Mhairi Keil, Thomas D. Love, and Sian Phillips

To determine the effectiveness of 3 commonly used beverages in restoring fluid and electrolyte balance, 8 volunteers dehydrated by 1.94% ± 0.17% of body mass by intermittent exercise in the heat, then ingested a carbohydrate-electrolyte solution (Gatorade), carbonated water/apple-juice mixture (Apfelschorle), and San Benedetto mineral water in a volume equal to 150% body-mass loss. These drinks are all are perceived to be effective rehydration solutions, and their effectiveness was compared with the rehydration effectiveness of Evian mineral water, which is not perceived in this way by athletes. Four hours after rehydration, the subjects were in a significantly lower hydration status than the pretrial situation on trials with Apfelschorle (–365 ± 319 mL, P = 0.030), Evian (–529 ± 319 mL, P < 0.0005), and San Benedetto (–401 ± 353 mL, P = 0.016) but were in the same hydration status as before the dehydrating exercise on Gatorade (–201 ± 388 mL, P = 0.549). Sodium balance was negative on all trials throughout the study; only with Apfelschorle did subjects remain in positive potassium balance. In this scenario, recovery of fluid balance can only be achieved when significant, albeit insufficient, quantities of sodium are ingested after exercise. There is a limited range of commercially available products that have a composition sufficient to achieve this, even though the public thinks that some of the traditional drinks are effective for this purpose.

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Stephen Heung-Sang Wong and Yajun Chen

Purpose:

This study examined the rehydration achieved by drinking different beverages during a short-term recovery period (REC) after exercise-induced dehydration.

Methods:

Thirteen well-trained men (age 22.1 ± 3.3 yr, body mass 61.2 ± 9.1 kg, VO2max 64.9 ± 4.0 ml · kg−1 · min−1, maximum heart rate 198 ± 7 beats/min) ran for 60 min on 3 occasions on a level treadmill at 70% VO2max. All trials were performed in thermoneutral conditions (21 °C, 71% relative humidity) and were separated by at least 7 d. During 4 hr REC, the subjects consumed either a volume of a carbohydrate-electrolyte beverage (CE), lemon tea (LT), or distilled water (DW) equal to 150% of the body weight (BW) lost during the previous run. The fluid was consumed in 6 equal volumes at 30, 60, 90, 120, 150, and 180 min of REC.

Results:

After the completion of the 60-min run, the subjects lost ~2.0% of their preexercise BW in all trials, and no differences were observed in these BW changes between trials. At the end of REC, the greatest fraction of the retained drink occurred when the CE drink was consumed (CE vs. LT vs. DW: 52% ± 18% vs. 36% ± 15% vs. 30% ± 14%, p < .05). The CE drink also caused the least diuretic effect (CE vs. LT vs. DW: 638 ± 259 vs. 921 ± 323 vs. 915 ± 210 ml, p < .05) and produced the optimal restoration of plasma volume (CE vs. LT vs. DW: 11.2% ± 2.0% vs. –3.1% ± 1.8% vs. 0.2% ± 2.1%, p < .05).

Conclusion:

The results of this study suggest that CE drinks are more effective than DW or LT in restoring fluid balance during short-term REC after exercise-induced dehydration.

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Kelsey Dow, Robert Pritchett, Karen Roemer, and Kelly Pritchett

forms of carbohydrate may be more practical and appealing for meeting post-exercise nutrition recommendations ( Dziedzic & Higham, 2014 ). Rehydration is another critical aspect of recovery between exercise bouts when recovery periods are limited to a few hours, such as during intermittent sport

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Ben Desbrow, Danielle Cecchin, Ashleigh Jones, Gary Grant, Chris Irwin, and Michael Leveritt

The addition of 25 mmol·L−1 sodium to low alcohol (2.3% ABV) beer has been shown to enhance post exercise fluid retention compared with full strength (4.8% ABV) beer with and without electrolyte modification. This investigation explored the effect of further manipulations to the alcohol and sodium content of beer on fluid restoration following exercise. Twelve male volunteers lost 2.03 ± 0.19% body mass (mean ± SD) using cycling-based exercise. Participants were then randomly allocated a different beer to consume on four separate occasions. Drinks included low alcohol beer with 25 mmol·L−1 of added sodium [LightBeer+25], low alcohol beer with 50 mmol·L−1 of added sodium [LightBeer+50], midstrength beer (3.5% ABV) [Mid] or midstrength beer with 25 mmolL−1 of added sodium [Mid+25]. Total drink volumes in each trial were equivalent to 150% of body mass loss during exercise, consumed over a 1h period. Body mass, urine samples and regulatory hormones were obtained before and 4 hr after beverage consumption. Total urine output was significantly lower in the LightBeer+50 trial (1450 ± 183 ml) compared with the LightBeer+25 (1796 ± 284 ml), Mid+25 (1786 ± 373 ml) and Mid (1986 ± 304 ml) trials (allp < .05). This resulted in significantly higher net body mass following the LightBeer+50 trial (-0.97 ± 0.17kg) compared with all other beverages (LightBeer+25 (-1.30 ± 0.24 kg), Mid+25 (-1.38 ± 0.33 kg) and Mid (-1.58 ± 0.29 kg), all p < .05). No significant changes to aldosterone or vasopressin were associated with different drink treatments. The electrolyte concentration of low alcohol beer appears to have more significant impact on post exercise fluid retention than small changes in alcohol content.

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Paola Rodriguez-Giustiniani and Stuart D.R. Galloway

state and replacing lost fluids on cessation of exercise is recommended; however, most of the research on this field has been done in males due to the uncertainty of including females in relation to menstrual cycle phase effects on fluid balance. Many factors affect fluid balance and rehydration, such

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Eva M.R. Kovacs, Regina M. Schmahl, Joan M.G. Senden, and Fred Brouns

The effect of a high (H) and a low (L) rate of post-exercise fluid consumption on plasma volume and fluid balance restoration was investigated. Eight well-trained cyclists were dehydrated at 3% of body weight (BW) by cycling at 28 °C. During the recovery period, they ingested a carbohydrate-electrolyte solution in a volume equivalent to 120% of BW loss. Randomly, they ingested 60%, 40%, and 20% in the 1 st, 2nd, and 3rd hours of the recovery period, respectively (H), or 24% · h−1 during 5 hours (L). BW loss was similar for both trials and resulted in a total drink intake of 2.6 ± 0.1 kg. Urine output in H exceeded significantly that of L in the 2nd and 3rd hours. This was reversed in the 5th and 6th hours. Plasma volume and fluid balance increased more rapidly in H compared to L. After 6 hours this difference disappeared. It is concluded that H results in a faster rate of plasma volume and fluid balance restoration compared to L, despite a temporary large urine output.

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Timothy P. Scheett, Michael J. Webster, and Kent D. Wagoner

On two occasions, 8 male subjects completed a dehydration protocol, immediately followed by a 180-min rehydration protocol, then a subsequent exercise bout. During each dehydration session, subjects lost 3.1 ± 0.4% body weight (BW) following discontinuous exercise in the heat (40 °C, 33 % rh). During the first 30 min of rehydration, subjects ingested either 1.0-g glycerol · kg body weight−1 + 30% of the total rehydration water volume (GLY), or 30% of the total rehydration water volume without glycerol (CON). The five remaining ingestions (every 30 min) were equal to 14% of the remaining fluid volume and were identical in nature. Fluid volume ingested equaled fluid volume lost during dehydration. Following the 180 min rehydration period, subjects cycled (~50% V̇O2peak) in the heat (40 °C, 33% rh) until volitional exhaustion. Three observations were made: (a) Following glycerol-induced rehydration, time to volitional exhaustion was greater during the subsequent exercise bout in the heat (CON: 38.0 ± 2.0, GLY 42.8 ± 1.0 min, p < .05); (b) glycerol-induced rehydration significantly increased plasma volume restoration within 60 min and at the end of the 180-min rehydration period; and (c) total urine volume was lower and percent rehydration was greater following GLY, but neither was significantly different.

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Lawrence E. Armstrong, Jorge A. Herrera Soto, Frank T. Hacker Jr., Douglas J. Casa, Stavros A. Kavouras, and Carl M. Maresh

This investigation evaluated the validity and sensitivity of urine color (Ucol), specific gravity (Usg), and osmolality (Uosm) as indices of hydration status, by comparing them to changes in body water. Nine highly trained males underwent a 42-hr protocol involving dehydration to 3.7% of body mass (Day 1, −2.64 kg), cycling to exhaustion (Day 2, −5.2% of body mass, −3.68 kg), and oral rehydration for 21 hr. The ranges of mean (across time) blood and urine values were Ucol, 1-7; Usg, 1.004-1.029; U08m, 117-1,081 mOsm • kg−1; and plasma osmolality (Posm), 280-298 mOsm ⋅ kg−1. Urine color tracked changes in body water as effectively as (or better than) Uosm, Usg, urine volume, Posm, plasma sodium, and plasma total protein. We concluded that (a) Ucol, Uosm, and Usg are valid indices of hydration status, and (b) marked dehydration, exercise, and rehydration had little effect on the validity and sensitivity of these indices.

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Joanne L. Fallowfield, Clyde Williams, and Rabindar Singh

Recovery from prolonged exercise involves both rehydration and replenishment of endogenous carbohydrate stores. The present study examined the influence of ingesting a carbohydrate-electrolyte (CE) solution following prolonged running, on exercise capacity 4 hr later. Twelve men and 4 women were divided into two matched groups, which were randomly assigned to either a control (P) or a carbohydrate (CHO) condition. Both groups ran at 70% of maximal oxygen uptake (VO2max) on a level treadmill for 90 min or until volitional fatigue (R,), and they ran at the same %VO2max to exhaustion 4 hr later to assess endurance capacity (R2). The CHO group ingested a 6.9% CE solution providing 1.0 g CHO · kg body weight−1 immediately post-R, and again 2 hr later. The P group ingested equal volumes of a placebo solution. Run times (mean ± SEM) for Rj did not differ between the groups (P 86.3 ± 3.8 min; CHO 87.5 ± 2.5 min). The CHO group ran 22.2 (±3.5) min longer than the P group during R2 (P 39.8 ± 6.1 min; CHO 62.0 ± 6.2 min) (p < .05). Thus, ingesting a 6.9% carbohydrate-electrolyte beverage following prolonged, constant-pace running improves endurance capacity 4 hr later.

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Louise M. Burke and Inigo Mujika

Postexercise recovery is an important topic among aquatic athletes and involves interest in the quality, quantity, and timing of intake of food and fluids after workouts or competitive events to optimize processes such as refueling, rehydration, repair, and adaptation. Recovery processes that help to minimize the risk of illness and injury are also important but are less well documented. Recovery between workouts or competitive events may have two separate goals: (a) restoration of body losses and changes caused by the first session to restore performance for the next and (b) maximization of the adaptive responses to the stress provided by the session to gradually make the body become better at the features of exercise that are important for performance. In some cases, effective recovery occurs only when nutrients are supplied, and an early supply of nutrients may also be valuable in situations in which the period immediately after exercise provides an enhanced stimulus for recovery. This review summarizes contemporary knowledge of nutritional strategies to promote glycogen resynthesis, restoration of fluid balance, and protein synthesis after different types of exercise stimuli. It notes that some scenarios benefit from a proactive approach to recovery eating, whereas others may not need such attention. In fact, in some situations it may actually be beneficial to withhold nutritional support immediately after exercise. Each athlete should use a cost–benefit analysis of the approaches to recovery after different types of workouts or competitive events and then periodize different recovery strategies into their training or competition programs.