John C. Quindry

Exercise-induced protection against myocardial apoptosis and necrosis: MnSOD, calcium-handling proteins, and calpain

Exercise provides protection against myocardial ischemia‐reperfusion (IR) injury. Understanding the mechanisms of this protection may lead to new interventions for the prevention and/or treatment of heart disease. Although presently these mechanisms are not well understood, reports suggest that manganese superoxide dismutase (MnSOD) and calpain may be critical mediators of this protection. We hypothesized that an exercise‐induced increase in MnSOD would provide cardioprotection by attenuating IR‐induced oxidative modification to critical Ca2+‐handling proteins, thereby decreasing calpain‐mediated cleavage of these and other proteins attenuating cardiomyocyte death. After IR, myocardial apoptosis and infarct size were significantly reduced in hearts of exercised animals compared with sedentary controls. In addition, exercise prevented IR‐induced calpain activation as well as the oxidative modification and calpain‐mediated degradation of myocardial Ca2+‐handling proteins (L‐type Ca2+ channels, phospholamban, and sarcoplasmic/endoplasmic reticulum calcium ATPase). Further, IR‐induced activation of proapoptotic proteins was attenuated in exercised animals. Importantly, prevention of the exercise‐induced increase in MnSOD activity via antisense oligonucleotides greatly attenuated the cardioprotection conferred by exercise. These results suggest that MnSOD provides cardioprotection by attenuating IR‐induced oxidation and calpain‐mediated degradation of myocardial Ca2+‐handling proteins, thereby preventing myocardial apoptosis and necrosis.—French, J. P., Hamilton, K L., Quindry, J. C., Lee, Y., Upchurch, P. A., Powers, S. K. Exercise‐induced protection against myocardial apoptosis and necrosis: MnSOD, calcium‐handling proteins, and calpain. FASEB J. 22, 2862–2871 (2008)

Relationship between serum creatine kinase activity following exercise-induced muscle damage and muscle fibre composition

Abstract In this study, we examined the relationship between serum creatine kinase activity following exercise-induced muscle damage and muscle fibre composition. Seventeen untrained males volunteered and underwent a [Vdot]O2max test, Wingate test, and an exercise-induced muscle damage protocol. Muscle soreness and blood samples were recorded before, immediately after, and 24, 48, 72, and 96 h after exercise. Biopsy samples from the vastus lateralis were collected one week after exercise-induced muscle damage and were assessed for muscle fibre composition. There was no significant relationship (P > 0.05) between muscle fibre composition and creatine kinase activity. A significant positive correlation (P < 0.05) was observed between soreness 48 h after exercise and type II and IIb fibres, and a significant negative correlation (P < 0.05) was observed between soreness 48 h after exercise and type I muscle fibres. Significant positive correlations were observed between soreness 48 h after exercise and the fatigue index, relative average power, and relative anaerobic capacity. Our results suggest that creatine kinase activity following exercise-induced muscle damage may not be related to muscle fibre proportions, and higher post-exercise muscular pain may be related to a predominance of type II muscle fibres and higher anaerobic capabilities.

Quercetin does not affect rating of perceived exertion in athletes during the Western States endurance run.

The purpose of this study was to measure the influence of quercetin supplementation on ratings of perceived exertion in ultramarathon runners competing in the 160-km Western States Endurance Run (WSER). Sixty-three runners were randomized to quercetin (Q) and placebo (P) groups, and under double blinded methods ingested four supplements per day with or without 250 mg quercetin for 3 weeks before the WSER. Thirty-nine of the 63 subjects (quercetin N = 18, placebo N = 21) finished the race. At the completion of exercise ratings of perceived exertion (RPE) were assessed at aid stations located at 40, 90, 125, 150, and 160 km (finish line). The pattern of change in RPE over time was not significantly different between the Q and P groups. Ratings of perceived exertion (RPE) did not significantly increase throughout the race (15.2 ± 2.9 at 40 km –14.2 ± 4.0 at 160 km) for both groups combined. Race times were not different between the groups (Q = 26.4 ± 0.7 h and P = 27.5 ± 0.6 h). Significant time main effects (p < 0.001) were found for both serum glucose and cortisol throughout the race. Quercetin supplementation for 3 weeks prior to the WSER had no effect on RPE during competitive self-paced ultramarathon running. Ratings of perceived exertion (RPE) did not increase in a linear fashion but instead fluctuated nonmonotonically throughout the self-paced endurance running event.

Effects of Rooibos Tea, Bottled Water, and a Carbohydrate Beverage on Blood and Urinary Measures of Hydration After Acute Dehydration

Rooibos tea contains polyphenol antioxidants, including flavonoids and phenolic acids that are potent free radical scavengers and has purported benefits for accelerated rehydration. The objective was to evaluate the effects of three different drinks (rooibos tea, bottled water, and a carbohydrate beverage) on blood and urinary markers of hydration after acute dehydration in collegiate wrestlers. Twenty-three athletes were recruited and followed a randomized, cross-over design with three different study arms comparing the effectiveness of rooibos tea, carbohydrate beverage (6% or 60 grams l−1), or bottled water (placebo) in promoting rehydration after a 3% reduction in body mass. Urine specific gravity (Usg) urine (Uosm) and plasma osmolarity (Posm), and plasma volume were measured pre- and post dehydration and at 1-h after rehydration. Statistical analyses utilized a 3 (conditions) × 3 (times) repeated measures analysis of variance to test main effects. Significant interaction effects were found for Posm and Uosm, both of which remained below basleline after 1-h rehydration in the rooibos tea and water trials. No significant interaction effects were found for either urine Usg or plasma volume shift. The findings of this study demonstrate that rooibos tea was no more effective in promoting rehydration than plain water, with significant changes being found for Posm and Uosm in the carbohydrate/electrolyte solution, in collegiate wrestlers after a 3% reduction in body mass and a rehydration period of 1-h when consuming 100% of their body weight loss.