Influence of carbohydrate, intense exercise, and rest intervals on hormonal and oxidative changes.
ABSTRACT This study compared effects of carbohydrate (CHO) and rest on oxidative stress during exercise. Cyclists (N = 12) completed 4 randomized trials at 64% Wattsmax under 2 conditions (continuous cycling for 2 h [C] and cycling with 3-min rest every 10 min for 2.6 h [R]). Subjects cycled under each condition while receiving 6% CHO and placebo (PLA). CHO and PLA were given preexercise (12 mL/kg) and during exercise (4 mL x kg(-1) x 15 min(-1)). Blood was collected preexercise, postexercise, and 1 h postexercise and assayed for F2-isoprostanes, hydroperoxides (LH), nitrite, antioxidant capacity, glucose, insulin, cortisol, and epinephrine. F2-isoprostanes and LH were lower in CHO. Glucose, cortisol, and epinephrine exhibited significant effects, with postexercise levels of glucose higher and cortisol and epinephrine lower in CHO during the R condition. This pattern was identical in the C condition (21). Oxidative stress during cycling was unaffected by use of short rest intervals but was diminished by CHO.
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ABSTRACT: BACKGROUND: Heavy exercise stresses immune function, however carbohydrate (CHO) supplementation has been shown to attenuate the decline in some measures of immune function after exercise. The purpose of the study was to investigate the impact of CHO supplementation on salivary immunoglobulin A (s-IgA) levels, interleukin 2 (IL-2), and interleukin 5 (IL-5), following an acute bout of resistance exercise (RE). METHODS: Ten resistance trained male collegiate athletes (21+/-2 yr; 174+/-6 cm, 80+/-11kg, 14%+/-4% fat) performed RE consisting of four exercises (leg press, lat pull-downs, bench press, and leg curls). Volunteers performed four sets of 10 repetitions at 65% of 1-RM, with 2 min rest between sets for all exercises. Subjects consumed either CHO beverage (1 g[bullet]kg-1 body weight) or placebo (P) prior to, during, and after RE (randomized, double blind design). Saliva and venous blood were collected pre-, post- and 90 min post-exercise. RESULTS: No change occurred in s-IgA from rest relative to osmolality or as a secretion rate (p > 0.05). IL-2 levels were unchanged by exercise in both trials (time effect p = 0.342). IL-5 was significantly (time effect p = 0.04) decreased between rest (1.55 +/- 0.07 pg[bullet]ml-1) and 90 min post-exercise (0.96 +/- 0 .11 pg[bullet]ml-1), with no difference between treatments (group x time effect p = 0.610). There was no time-by-treatment interaction (p < 0.05) observed between CHO and P treatments for s-IgA or IL-5. CONCLUSION: IL-5 decreases after RE, but s-IgA and IL-2 levels remain stable. CHO ingestion prior to-, during or following RE did not appear to alter salivary immune responses.Journal of the International Society of Sports Nutrition 03/2013; 10(1):14. · 1.83 Impact Factor
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ABSTRACT: Carbohydrate supplementation is a popular nutritional practice used in tennis to enhance physical capacities, motor-skill performance, and delay fatigue. However, the effects of carbohydrate supplementation on physiological and perceptual responses during tennis match play are not established. This double blind, randomized, placebo-controlled crossover study was designed to determine the influence of carbohydrate supplementation (0.5g•kg•h) on glycemia, salivary hormones (cortisol and testosterone) concentration, salivary IgA concentration and ratings of perceived exertion (RPE) during 3 h of tennis match play in 12 well trained tennis players. The only significant difference between the two conditions was a lower salivary cortisol concentration post-match in the carbohydrate trial (p<0.05); however, there was a trend for higher glucose concentration (p = 0.06) and lower session-RPE (p = 0.08) following tennis match play in the carbohydrate condition, which may have some practical implications. There was no change in salivary testosterone, salivary IgA and RPE responses during tennis match play between conditions (p>0.05). These data indicate that carbohydrate ingestion during 3 h of competitive tennis match play helps to maintain glycemia and attenuates the increase in salivary cortisol concentration compared to placebo.The Journal of Strength and Conditioning Research 07/2013; · 1.80 Impact Factor
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ABSTRACT: The level of F₂-isoprostanes (F₂-IsoP) in blood or urine is widely regarded as the reference marker for the assessment of oxidative stress. As a result, nowadays, F₂-IsoP is the most frequently measured oxidative stress marker. Nevertheless, determining F₂-IsoP is a challenging task and the measurement is neither free of mishaps nor straightforward. This review presents for the first time the effect of acute and chronic exercise on F₂-IsoP levels in plasma, urine and skeletal muscle, placing emphasis on the origin, the methodological caveats and the interpretation of F₂-IsoP alterations. From data analysis, the following effects of exercise have emerged: (i) acute exercise clearly increases F₂-IsoP levels in plasma and this effect is generally short-lived, (ii) acute exercise and increased contractile activity markedly increase F₂-IsoP levels in skeletal muscle, (iii) chronic exercise exhibits trend for decreased F₂-IsoP levels in urine but further research is needed. Theoretically, it seems that significant amounts of F₂-IsoP can be produced not only from phospholipids but from neutral lipids as well. The origin of F₂-IsoP detected in plasma and urine (as done by almost all studies in humans) remains controversial, as a multitude of tissues (including skeletal muscle and plasma) can independently produce F₂-IsoP.Progress in lipid research 10/2010; 50(1):89-103. · 10.67 Impact Factor