A single bout of exercise induces a transient alteration in gene expression of the insulin signaling pathway / 体力科学

The present study was conducted to examine whether gene expression of the insulin signaling pathway is activated in response to a single bout of exercise. Adult male rats underwent a single bout of treadmill exercise for 90 min at 22 m/min on a 6°C incline. The animals were sacrificed immediately after exercise or after a predetermined post-exercise recovery period of up to 48 h, and the level of mRNA in the gastrocnemius muscle was measured by the RT-PCR method. Immediately after exercise, mRNA levels of insulin signal transduction intermediates in the gastrocnemius muscle were lower in the exercise group than in the controls. Following this tendency reduction, mRNA levels of insulin receptor, IRS-1, PI 3-kinase, SH-PTP2 and Nck were higher in the exercise group than in the controls. The levels of PI 3-kinase mRNA was significantly higher in the exercise group than in the controls within 6 h after exercise, while levels of mRNA for insulin receptor, IRS-1, SH-PTP2 and Nck were significantly higher in the the exercise group than in the controls at 48 h after exercise. Gene expression of oncogenes was also affected by a single bout of exercise. Levels of c-fos and c-myc mRNA were significantly higher than in the controls immediately after exercise, while the level of c-jun mRNA was lower in the exercise group at 3 h after exercise. Thus, a single bout of exercise affects the gene expression of insulin signal transduction pathway intermediates and oncogenes in rat gastrocnemius muscle. The present findings suggest that an exercise-induced adaptive increase of skeletal muscle insulin sensitivity is a cumulative effect of a single bout of exercise on the gene expression of insulin signal transduction pathway intermediates.

Low prevalence of disordered eating patterns and menstrual irregularities in chinese female athletes / 体力科学

The purpose of this study was to examine the prevalence of disordered eating patterns (DEP) and menstrual irregularities in Chinese female athletes (n=881) and nonathletic controls (n=147), by using Eating Attitudes Test-26 (EAT-26) and written questionnaires. The athletes were divided into the following 6 categories : technical, endurance I (leanness is considered important for athletic performance) and II (leanness is less important), aesthetic, ball-game and power sports. The prevalence of DEP in the athletes estimated by EAT-26 was low (technical 1.5%, endurance I 3.3%, endurance 11 1.6%, aesthetic 3.0%, ball-game 3.0% and power sports 0.9%), and didn't significantly differ from that in nonathletic controls (0.7%) . Amenorrheic athletes were not observed in endurance I and II, aesthetic, or ball-game sports and very low prevalence rates for amenorrhea were found in the athletes in technical (0.5%) and power sports (0.4%) . These figures represent no significant differences between athletes and nonathletes in the prevalence rates of amenorrhea. It was suggested that a low prevalence of DEP in Chinese athletes stems from low socioculturally- and socioeconomically-imposed desires to be thin and low requirements for weight loss to improve athletic performance. Also, the present data suggest that the low incidence of amenorrhea in Chinese athletes is partly associated with the low prevalence of DEP.

Prevalence of disordered eating patterns and menstrual status in japanese female athletes / 体力科学

This study investigated the desire and its reasons for weight loss, the prevalence of disordered eating patterns and menstrual status, by using written questionnaires and Eating Attitude Test-26 (EAT-26), in Japanese female athletes (n=1000) and nonathletic controls (n=593) . Athletes were divided into the following 6 categories : technical (n=84), endurance I (n=84) and II (n=76), aesthetic (n=120), ball-game (n=447), and power sports (n=189) . Endurance I consisted of athletes competing in sports where leanness were considered important, while endurance II consisted of athletes competing in sports where leanness is less important. In each category, about four fifths of the athletes wanted to reduce their present weight. As to the reasons for weight loss, the athletes, especially those in the categories of endurance I (79%), power (52%) and aesthetic (34%) sports, reported that they prefer to be thin for improving their athletic performance. The prevalence of disordered eating patterns estimated by EAT-26 was significantly higher (P<0.05) in the athletes of endurance I (20%) and aesthetic (12%) groups than in the nonathletic controls (3 %) . In the athletes of these two sporting event categories, higher rates of amenorrhea (endurance I 20% and aesthetic 7 % vs. nonathlets 1 %) were found to be accompanied by lower values of obesity index and BMI. These data indicate a significantly higher prevalence of disordered eating patterns and menstrual dysfunction in the athletes involved in sports where leanness is emphasized, and a close relationship among undernutrition, low body weight and menstrual dysfunction.