Relationship between breath isoprene excretion and oxidative stress responses to submaximal exercise / 体力科学

The physiological functions of expiratory isoprene, which is abundantly contained in human breath, are not well known. Recently, breath isoprene has been proposed to be related to oxidative stress, although no direct evidence has been reported. Therefore, the purpose of this study was to investigate the relationship between breath isoprene and oxidative stress status. Ten healthy male subjects performed a 20-min submaximal step-load cycling exercise, the intensity of which corresponded to a 60% peak oxygen uptake after a 10-min rest. Breath isoprene excretion during the exercise was calculated from the product of minute ventilation and isoprene expiratory concentration. To evaluate the oxidative stress, we collected blood samples from the subject’s fingertips before and immediately after the end of the exercise, and then diacron reactive oxygen metabolites (d-ROMs), which is an index of oxidative stress level, and biological antioxidant potential (BAP), which is an index of antioxidant potential, were measured. The breath isoprene concentration at the rest was significantly positively correlated with the ratio from BAP to d-ROMs (BAP/d-ROMs), which is an index of latent antioxidant potential (r = 0.63, P < 0.05). Furthermore, the change in breath isoprene excretion from before to after the exercise was significantly negatively correlated with the change in d-ROMs (r = -0.73, P < 0.05) and positively correlated with the change in BAP/d-ROMs (r = 0.88, P < 0.01). These results suggest that isoprene might play a role in the control of oxidative stress.

THE OPTIMUM INTENSITY AND MODE OF COOLING DOWN PROCEDURES AFTER POST REPETITIVE INTERMITTENT HIGH-INTENSITY EXERCISE / 体力科学

The purpose of this study was to compare the effects derived from different modes of active cooling down procedures post repetitive intermittent high-intensity exercise. Seven Japanese male swimmers underwent repetitive 3 bouts of Wingate anaerobic tests on the 1^st day and another Wingate on the following 2^nd day. In each 3 intervals and post all the Wingate testing on the 2^nd day, the participants performed a cooling down randomly chosen from 3 different intensities of 10-min bike-riding and a 10-min static stretching. As to muscle power outputs and emotional conditions, the optimum cooling down intensities were observed at 80% ventilatoly threshold (VT) after the 1^st set and 60% VT level after the 2^nd set. Effective intensities of blood lactate removal rate were observed at 60% and 80% VT level. Thus, the optimum cooling down post repetitive intermittent high-intensity exercise could be dynamic bike-riding at 60% or 80% VT level.

THE EFFECTS OF SOY PEPTIDE ON ISOMETRIC PERFORMANCES AND SERUM CK AND LDH TRENDS AFTER HIGH INTENSITY REPETITIVE ECCENTRIC EXERCISE STRESS / 体力科学

This study was designed to investigate the effects of supplementing soy peptide on isometric performances and serum CK and LDH trends after a high intensity eccentric exercise stress. Study subjects consisted of 13 males and were divided into 2 groups. They were instructed to take 4,000 mg of soy peptide or placebo orally before and for 7 days following the initial exercise stress. Soy peptide group revealed significantly faster improvements in knee extension performance at 72 hr-post the eccentric exercise (p<0.05). Comparing with placebo group, soy peptide group showed significantly lower serum LDH activity 168 hr after the exercise (p<0.05), while as to serum CK levels, significant difference was not observed between those 2 groups. These results indicate that oral supplementation of soy peptide could induce not only reduction in serum LDH activity level, but also faster recovering in isometric performance after high intensity repetitive eccentric exercise.

THE SYNERGIC EFFECTS OF COENZYMEQ10 AND CREATINE THROUGH ORAL INTAKE ON REPETITIVE SHORT DURATION HIGH-INTENSITY EXERCISE / 体力科学

A double-blind placebo-controlled trial was undertaken to evaluate the synergic effects of coenzymeQ10 (CoQ10) and creatine (Cr) through oral supplementation on the intermittent short duration high-intensity exercise on a cycle ergometer. Twenty-eight male athletes were divided into four groups of CoQ10 and Cr (CoQ10+Cr), CoQ10 (CoQ10+Pl), Cr (Pl+Cr) and placebo group (Pl+Pl). Each participant was instructed to have 100 mg of CoQ10 and/or 5 g of Cr per day for 2 weeks. Repetitive 5 bouts of 10-sec high-intensity cycle exercise tests were performed before and after supplementations. After supplementations, subjects in (CoQ10+Cr) revealed most improved performance in mean power outputs at the 2^nd (p<0.05), the 3^rd (p<0.05), the 4^th (p<0.05) and the 5^th set (p=0.06), comparing with the participants in the other 3 groups. These findings suggest that enhanced mean power output on repetitive short duration high-intensity exercise can be acquired after supplementing CoQ10 combined with Cr.