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.
Ben Desbrow, Danielle Cecchin, Ashleigh Jones, Gary Grant, Chris Irwin and Michael Leveritt
Nicola C. Sutton, David J. Childs, Oded Bar-Or and Neil Armstrong
The purpose of this study was to develop a nonmotorized treadmill sprint test (ExNMT) to assess children’s short-term power output, to establish the test’s repeatability, and to compare the results to corresponding Wingate anaerobic test (WAnT) measurements. Nineteen children (aged 10.9±0.3 years) completed 2 ExNMTs and 2 WAnTs. Statistical analysis revealed coefficients of repeatability for the ExNMT that compared very favorably with the WAnT for both peak power (26.6 vs. 44.5 W) and mean power (15.3 vs. 42.1 W). The validity of the ExNMT as a test of anaerobic performance is reflected by significant correlations (p ≤.05) with the WAnT (peak power, r = 0.82; mean power, r = 0.88) and reinforced by the relatively high post-exercise blood lactate concentrations (7.1 ± 1.3 vs. 5.6 ± 1.5 mmol · L−1 for the ExNMT and WAnT, respectively). This study has developed a promising laboratory running test with which to examine young people’s short-term power output.
Stephen Hill, Wesley Box and Robert A. DiSilvestro
Lipid peroxides can be both a product and an initiator of oxidant stress. Conceivably, exercise can either increase concentrations of lipid peroxides (by causing oxidant stress), or decrease them (by accelerating peroxide breakdown). The net effect could depend on exercise intensity and nutritional intake of antioxidants. The present study examined the response of serum lipid peroxides to the combination of moderate intensity, weight resistance exercise plus intake of soy protein, a source of antioxidant phytochemicals. Recreationally trained, young adult men (N = 18) consumed soy protein or antioxidant-poor whey protein for 4 weeks (40 g protein/d) before a session of moderate intensity, weight resistance exercise. In the soy group, exercise decreased values for serum lipid peroxides at 5 min, 3 h, and 24 h post-exercise. The whey group showed the depression only at 24 h. In both the soy and whey groups, a small rise was seen for interleukin-8, which is consistent with the idea that the exercise session induced a moderate muscle stress. In summary, a moderate intensity, weight resistance exercise session, despite inducing mild inflammation, depressed plasma serum peroxide values, especially when combined with 4 weeks of soy consumption.
Andrea D. Marjerrison, Jonah D. Lee and Anthony D. Mahon
This study examined the effect of pre exercise carbohydrate (CHO) feeding on performance on a Wingate anaerobic test (WAnT) in 11 boys (10.2 ± 1.3 y old). Four WAnTs with 2 min recovery were performed 30 min after consuming a CHO (1 g CHO/kg) or placebo drink. Peak power (PP) and mean power (MP) were similar between trials. PP ranged from 241.1 ± 82.2 to 223.1 ± 57.9 W with carbohydrate and from 238.2 ± 76.1 to 223.4 ± 52.3 W with placebo. MP ranged from 176.3 ± 58.4 to 151.1 ± 37.5 W with carbohydrate versus 178.0 ± 45.8 to 159.1 ± 32.7 W with placebo. Pre exercise glucose was significantly higher in CHO versus placebo (7.0 ± 1.0 vs. 5.5 ± 0.5 mmol/L), but post exercise values were not different. Blood lactate was similar between trials but increased over time. This study found that the ingestion of a CHO solution before exercise did not influence power output during repeated performances of the WAnT.
Dru A. Henson, David C. Nieman, E. Edward Pistilli, Brian Schilling, AnnaRita Colacino, Allan C. Utter, Omar R. Fagoaga, Debra M. Vinci and Sandra L. Nehlsen-Cannarella
The influence of 6% carbohydrate ingestion and age on PHA-induced lymphocyte proliferation and in vitro cytokine production was studied in 48 runners following a competitive marathon. Runners were randomly assigned to carbohydrate (C; n = 23) and placebo (P; n = 25) groups, with blood samples taken before, immediately after, and 1.5 hr post-race. C versus P ingestion resulted in higher plasma glucose, lower plasma corlisol, reduced neutrophilia, and mono-cytosis during recovery, but had no effect on the post-exercise reduction in T-lymphocytes or NK cells, or on race times. No group differences were observed for PHA-induced lymphocyte proliferation or cytokine production. However, for all subjects combined, lymphocyte proliferation and IFN-γ secretion decreased significantly below pre-race values by 1.5 hr of recovery, and these were negatively correlated with plasma cortisol. Young (<50 years; n = 36) and old (≥50 years; n = 12) runners exhibited parallel post-race declines in lymphocyte proliferation and IFN-γ secretion, with the older group exhibiting a 33–59% lower proliferation at each time point. In conclusion, PHA-induced lymphocyte proliferation and cytokine production decreased significantly following a marathon, and this decrease was strongly linked to cortisol and only partially linked to T-cell changes. This decrease occurred in both younger and older runners and was not influenced by carbohydrate.
Stacie L. Wing-Gaia, Andrew W. Subudhi and Eldon W. Askew
The purpose of this study was to assess the effects of purified oxygenated water on exercise performance under hypoxic conditions. Nine recreational male cyclists (age = 26.6 ± 5.2 y, weight = 87.6 ± 19.5 kg, VO2peak = 46.5 ± 5.9 mL · kg−1 · min−1) completed two 600 kJ cycling time trials under hypoxic conditions (FIO2 = 13.6% O2, Pbar = 641 mmHg) separated by 2 wk. Trials were completed following 3 d ingestion of 35 mL · kg−1 · d−1 of control (CON) or experimental (EXP) water. Time to completion, heart rate (HR), rate of perceived exertion (RPE), pulse oximetry (SaO2), blood gases (PcO2 and PcCO2), and lactate were measured during the trials. Hydration was assessed with pre- and post-exercise body weight and 24-h urine specific gravity. Performance, hydration, and blood oxygenation were unaffected by EXP water. Results of this study suggest that purified oxygenated water does not improve exercise performance in moderately active males.
Allan H. Goldfarb, Richard J. Bloomer and Michael J. McKenzie
To examine the effects of an antioxidant treatment on blood lactate, protein carbonyls (PC), and glutathione status, 42 male rats were assigned to either a control treatment (water, C) or one of two Microhydrin® treatments (added to water, MH I or MH II). Rats from each treatment were assigned to either exercise (60 min of running) or rest. A treatment-by-time interaction was noted for blood lactate, with elevations only in the C and MH I treatments post-exercise (~ 2.54 and 2.5 mM, respectively). Both treatment and time main effects were noted for PC. Exercise resulted in an increase in PC for both Microhydrin treatments with significantly greater PC compared to C. Total blood glutathione was unaffected by treatment or exercise. Exercise increased the ratio of oxidized to total glutathione and the MH II treatment resulted in a greater ratio compared to the other treatments. In conclusion, MH II results in lower blood lactate, while resulting in an increase in the concentration of oxidized protein and glutathione, suggesting heightened oxidative stress.
Elaine M. Murtagh, Colin Boreham, Alan Nevill, Gareth Davison, Tom Trinick, Ellie Duly, Mawloud El-Agnaf and Marie H. Murphy
Markers of inflammation are emerging as novel indices of cardiovascular risk. These markers have been shown to alter acutely after intense exercise; however, the effects of more moderate intensity exercise in healthy individuals is not known. Walking forms a cornerstone of physical activity promotion, so the inflammatory response to this exercise merits investigation. This study evaluated the effects of a 45-min walk on C-reactive protein (CRP) and interleukin 6 (IL-6), in sedentary, overweight men.
Fifteen men (49.7 ± 5.9 y) walked for 45 min at 60 to 70% of predicted maximum heart rate. Fasted blood samples were taken prior to and immediately 1 hr and 24 h post-walk.
IL-6 decreased from 1 h post-walk to 24 h post-walk (P < 0.01). No significant changes were observed in CRP.
These findings suggest that 45 min walking at 60 to 70% HRmax-p causes a decrease in IL-6 24 h post-exercise, but does not evoke a significant response in CRP levels.
Paula Robson-Ansley, Martin Barwood, Clare Eglin and Les Ansley
Fatigue is a predictable outcome of prolonged physical activity; yet its biological cause remains uncertain. During exercise, a polypeptide messenger molecule inter-leukin-6 (IL-6) is actively produced. Previously, it has been demonstrated that administration of recombinant IL-6 (rhIL-6) impairs 10-km run performance and heightened sensation of fatigue in trained runners. Both high carbohydrate diets and carbohydrate ingestion during prolonged exercise have a blunting effect on IL-6 levels post endurance exercise. We hypothesized that carbohydrate ingestion may improve performance during a prolonged bout of exercise as a consequence of a blunted IL-6 response. Seven recreationally trained fasted runners completed two 90-min time trials under CHO supplemented and placebo conditions in a randomized order. The study was of a double-blinded, placebo-controlled, cross-over study design. Distance covered in 90 min was significantly greater following exogenous carbohydrate ingestion compared with the placebo trial (19.13 ± 1.7 km and 18.29 ± 1.9 km, respectively, p = .0022). While post exercise IL-6 levels were significantly lower in the CHO trial compared with the placebo trial (5.3 ± 1.9 pg·mL−1 and 6.6 ± 3.0 pg·mL−1, respectively; p = .0313), this difference was considered physiologically too small to mediate the improvement in time trial performance.
Marcia A. Chan, Alexander J. Koch, Stephen H. Benedict and Jeffrey A. Potteiger
The effect of carbohydrate supplementation (CHO) on interleukin 2 (IL-2) and interleukin 5 (IL-5) secretion following acute resistance exercise was examined in 9 resistance-trained males. Subjects completed a randomized, double-blind protocol with exercise separated by 14 days. The exercise consisted of a high intensity, short rest interval squat workout. Subjects consumed 1.0 g · kg body mass-1 CHO or an equal volume of placebo (PLC) 10 min prior to and 10 min following exercise. Blood was collected at rest (REST), immediately post exercise (POST), and at 1.5 h of recovery (1.5 h POST). Isolated peripheral blood mononuclear cells were stimulated with PHA and assayed for IL-2 and IL-5 secretion. IL-2 secretion was significantly decreased at POST for both the PLC and CHO groups. However, the degree of decrease was less in the CHO group (16%) than in the PLC group (48%), and this difference was statistically significant. These responses were transient, and the values returned to normal by 1.5 h POST. A mild and transient but significant decrease in IL-5 secretion by the PLC group was observed at POST (26%) compared to REST. No significant decrease was observed in IL-5 secretion for CHO from REST to POST (12%). These data support a possible effect of carbohydrate supplementation on IL-2 and IL-5 secretion following high-intensity resistance exercise.