Article

Influence of carbohydrate, intense exercise, and rest intervals on hormonal and oxidative changes

Dept. of Health, Leisure, and Exercise Science, Appalachian State University, Boone, NC 28608, USA.
International journal of sport nutrition and exercise metabolism (Impact Factor: 2.44). 11/2007; 17(5):478-90.
Source: PubMed

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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    • "The PC concentrations were higher when BM losses were increased. Additionally, PC concentrations were greater when BG levels decreased, which appears to corroborate previous findings that oxidative stress (McAnulty et al., 2003, 2007) and subsequently immune function (Nieman et al., 2006) may be linked with levels of BG. Furthermore, Laitano et al. (2010) revealed that oxidative stress levels were greater during hyperthermic conditions, but we have not been able to duplicate these findings (Hillman et al., 2011) possibly due to the lower fitness level and thus inferior antioxidant potential of their subjects. "
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    ABSTRACT: Dehydration has been shown to augment cellular stress. Glycerol hyperhydration can delay dehydration, which may decrease the level of pre- and post-exercise oxidative stress. This study aimed to compare the effects of glycerol (G) or water (W) hyperhydration with no hyperhydration (C) on oxidative stress, thermoregulation, and cycle performance. Seven trained males consumed 1.2 g of glycerol·kg(-1) body mass (BM) in 26 ml·kg(-1) BM water or equal volume water to achieve hyperhydration followed by a 90 min time trial. Total glutathione increased post exercise (PE) in all trials (p < 0.01), while oxidized glutathione (p < 0.05) and protein carbonyl concentrations (p < 0.001) were increased PE for the C trial only. Mean body temperature and heart rate increased with exercise but were not different between interventions. Total distance covered and power outputs were not different between interventions. Fluid intake attenuated oxidative stress but did not enhance thermoregulation or performance.
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    • "The central premise behind our hypothesis was that carbohydrate ingestion would blunt the rise of epinephrine and norepinephrine during RE, and thus alter s-IgA and circulating cytokines measured as compared to control. Some previous studies [22] of carbohydrate ingestion during exercise have found significant reductions in epinephrine and norepinephrine while others have found no effect [28]. Thus the impact of carbohydrate ingestion on the catecholamine response to exercise appears to be variable. "
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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•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•ml-1) and 90 min post-exercise (0.96 ± 0 .11 pg•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.
    Full-text · Article · Mar 2013 · Journal of the International Society of Sports Nutrition
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    ABSTRACT: The purpose of this study was to determine whether an isocaloric beverage with added protein and vitamins (CHOPA) would influence oxidative stress and inflammation after cycling to exhaustion as indicated by plasma protein carbonyls (PC), lipid hydroperoxides (LOOH), and interleukin-6 (IL-6). Twelve trained men (18-33 yr) volunteered and performed this randomized crossover study. Participants cycled at 70% VO2peak until fatigue and at 80% VO2peak 22-24 hr later to fatigue with either carbohydrate or CHOPA. Blood collected before the cycling at rest and 24, 48, and 72 hr after the exercise was analyzed for PC and LOOH spectrophotometrically and for IL-6 via an enzyme-linked immunosorbent assay. The data were analyzed with SPSS using repeated-measures ANOVA. PC demonstrated significant treatment (p = .037) and time (p = .004) effects with no Treatment x Time interaction. PC was higher in the CHOPA treatment than with CHO independent of time and increased at 24 (48%), 48 (59%), and 72 (67%) hr after exercise compared with preexercise values. Resting LOOH and IL-6 did not have any significant changes with time or treatment. These data indicate that an isocaloric CHOPA drink after 2 cycling bouts to exhaustion will exacerbate the resting PC level compared with an isocaloric drink, with no influence on plasma LOOH or IL-6. In addition, a modest significant increase in PC over time independent of treatment occurred, which suggests a mild oxidative stress in the days after exhaustive exercise.
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