The purpose of this study was to determine the effects of antioxidant therapy on indirect markers of muscle damage following eccentric exercise (EE). Eighteen women were randomized to an antioxidant supplement or a placebo before a bout of EE. Plasma creatine kinase (CK) activity, muscle soreness (MS), maximal isometric force (MIF), and range of motion (ROM) were assessed before and through 14 d postexercise. Eccentric exercise resulted in an increase in CK activity and MS, and a drop in MIF and ROM during the days following EE, which returned to baseline values 14 d after EE in both groups. Antioxidants attenuated the CK activity and MS response to the EE, while little difference was noted between groups in MIF or ROM. These fndings suggest that antioxidant supplementation was helpful in reducing the elevations in plasma CK activity and MS, with little impact on MIF and ROM loss.
Richard J. Bloomer
Kelsey H. Fisher-Wellman and Richard J. Bloomer
Carbohydrate powder in the form of maltodextrin is widely used by athletes for postexercise glycogen resynthesis. There is some concern that such a practice may be associated with a postprandial rise in reactive oxygen and nitrogen species production and subsequent oxidation of macromolecules. This is largely supported by findings of increased oxidative-stress biomarkers and associated endothelial dysfunction after intake of dextrose.
To compare the effects of isocaloric dextrose and maltodextrin meals on blood glucose, triglycerides (TAG), and oxidative-stress biomarkers in a sample of young healthy men.
10 men consumed isocaloric dextrose and maltodextrin powder drinks (2.25 g/kg) in a random-order, crossover design. Blood samples were collected premeal (fasting) and at 1, 2, 4, and 6 hr postmeal and assayed for glucose, TAG, malondialdehyde, hydrogen peroxide, nitrate/nitrite, and Trolox-equivalent antioxidant capacity.
Significant meal effects were noted for glucose total area under the curve (p = .004), with values higher for the dextrose meal. No other statistically significant meal effects were noted (p > .05). With respect to the 2 (meal) × 5 (time) ANOVA, no significant interaction, time, or meal effects were noted for any variable (p > .05), with the exception of glucose, for which a main effect for both meal (p < .0001) and time (p = .0002) was noted.
These data indicate that carbohydrate meals, consumed as either dextrose or maltodextrin, pose little postprandial oxidative insult to young, healthy men. As such, there should be minimal concern over such feedings, even at high dosages, assuming adequate glucose metabolism.
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.
Richard J. Bloomer, Bradford Cole and Kelsey H. Fisher-Wellman
High-kilocalorie feedings induce oxidative stress. Acute exercise has the potential to attenuate postprandial oxidative stress. No study has determined whether there are racial differences in postprandial oxidative stress with and without a preceding bout of acute exercise.
To investigate the impact of acute exercise on blood oxidative- stress biomarkers, triglycerides (TAG), and glucose in African American (AA) and White (W) women.
10 AA (age 29 ± 3 yr, body-mass index [BMI] 31 ± 3 kg/m2) and 10 W (age 30 ± 2 yr, BMI 30 ± 3 kg/m2) women consumed a meal of 1.2 g of fat and carbohydrate and 0.25 g of protein per kilogram body mass, on 2 occasions—with and without a session of aerobic exercise 15 min preceding the meal (45 min cycling at 65% heart-rate reserve)—in a random-order crossover design. Blood samples were collected premeal (fasted), and at 1, 2, 4, and 6 hr postmeal and assayed for TAG, glucose, xanthine oxidase activity, hydrogen peroxide (H2O2), and malondialdehyde (MDA). Area under the curve (AUC) was calculated for each variable.
AUC was lower for AA compared with W for both the exercise and the no exercise conditions for H2O2, MDA, and TAG (p < .01). However, acute exercise had no effect on decreasing the AUC for any variable in either AA or W women (p > .05).
Postprandial lipemia and oxidative stress are lower in AA than in W overweight/obese women. However, acute exercise, performed at the intensity and duration in the current study, does not influence postprandial lipemia or oxidative stress in AA or W women.
Richard J. Bloomer, Gary A. Sforzo and Betsy A. Keller
The purpose of this study was to examine the effects of postexercise feeding on plasma levels of insulin, testosterone, cortisol, and testosteronexortisol (T:C). Ten experienced, resistance trained males (20.7 ± 0.95 years) were given whole food (WF: protein 38 g; carbohydrate 70 g; fat 7 g), a supplemental drink (SD; isocaloric and isonitrogenous to WF), an isocaloric carbohydrate beverage (C), or a placebo beverage (P) immediately, 2 and 4 hours after a standardized weight training protocol on 4 days, each separated by 1 week, in a repeated measures design. Subjects also received a standardized meal at 7 and 12 hours postexercise. Insulin, testosterone, and cortisol were measured pre-exercise and during 24 hours of recovery (at 0.5,2.5,4.5,8, and 24 hours) using venous blood samples. Significant (condition × time) interactions were found for insulin, testosterone, and T:C, but not for cortisol (p < .05). The SD yielded a greater response for insulin than all other conditions. Conversely. P demonstrated the greatest values for testosterone and T:C at 2.5 and 4.5 hours postexercise. Cortisol did not vary between conditions and there were no condition effects for insulin, testosterone, cortisol, and T:C at 8 or 24 hours. In conclusion, the efficacy of postexercise feeding for optimizing T:C and muscle growth is unclear; however, consumption of SD appears to maximize circulating insulin for several hours following resistance exercise.
Richard J. Bloomer, Andrew Fry, Brian Schilling, Loren Chiu, Naruhiro Hori and Lawrence Weiss
This investigation was designed to determine the effects of astaxanthin on markers of skeletal muscle injury. Twenty resistance trained men (mean ± standard error of the mean: age, 25.1 ± 1.6 y; height, 1.79 ± 0.02 m; weight, 86.8 ± 4.4 kg) were assigned to either a placebo (1732 mg safflower oil, n = 10) or astaxanthin (BioAstin; 1732 mg safflower oil; haematococcus algae extract [contains 4 mg astaxanthin and 480 mg lutein], n = 10). Subjects consumed their assigned treatment for 3 wk prior to eccentric exercise (10 sets of 10 repetitions at 85% of one repetition maximum) and through 96 h post-exercise. Muscle soreness, creatine kinase (CK), and muscle performance was measured before and through 96 h post-exercise. A similar response was observed for both treatment groups for all dependent variables, indicating that in resistance trained men, astaxanthin supplementation does not favorably affect indirect markers of skeletal muscle injury following eccentric loading.
Webb A. Smith, Andrew C. Fry, Lesley C. Tschume and Richard J. Bloomer
The purpose of this study was to evaluate the effect of glycine propionyl-Lcarnitine (GPLC) supplementation and endurance training for 8 wk on aerobicand anaerobic-exercise performance in healthy men and women (age 18–44 yr). Participants were randomly assigned to 1 of 3 groups: placebo (n = 9), 1 g/d GPLC (n = 11), or 3 g/d GPLC (n = 12), in a double-blind fashion. Muscle carnitine (vastus lateralis), VO2peak, exercise time to fatigue, anaerobic threshold, anaerobic power, and total work were measured at baseline and after an 8-wk aerobic-training program. There were no statistical differences (p > .05) between or within the 3 groups for any performance-related variable or muscle carnitine concentrations after 8 wk of supplementation and training. These results suggest that up to 3 g/d GPLC for 8 wk in conjunction with aerobic-exercise training is ineffective for increasing muscle carnitine content and has no significant effects on aerobic- or anaerobic-exercise performance.
Stephanie Chester, Audrey Zucker-Levin, Daniel A. Melcher, Shelby A. Peel, Richard J. Bloomer and Max R. Paquette
The purpose of this study was to compare knee and hip joint kinematics previously associated with anterior knee pain and metabolic cost among conditions including treadmill running (TR), standard elliptical (SE), and lateral elliptical (LE) in healthy runners. Joint kinematics and metabolic parameters of 16 runners were collected during all 3 modalities using motion capture and a metabolic system, respectively. Sagittal knee range of motion (ROM) was greater in LE (P < .001) and SE (P < .001) compared with TR. Frontal and transverse plane hip ROM were greater in LE compared with SE (P < .001) and TR (P < .001). Contralateral pelvic drop ROM was smaller in SE compared with TR (P = .002) and LE (P = .005). Similar oxygen consumption was found during LE and TR (P = .39), but LE (P < .001) and TR (P < .001) required greater oxygen consumption than SE. Although LE yields similar metabolic cost to TR and produces hip kinematics that may help strengthen hip abductors, greater knee flexion and abduction during LE may increase symptoms in runners with anterior knee pain. The findings suggest that research on the implications of elliptical exercise for injured runners is needed.