Voluntary stand-up physical activity enhances endurance exercise capacity in rats

Involuntary physical activity induced by the avoidance of electrical shock leads to improved endurance exercise capacity in animals. However, it remains unknown whether voluntary stand-up physical activity (SPA) without forced simulating factors improves endurance exercise capacity in animals. We examined the eff ects of SPA on body weight, cardiac function, and endurance exercise capacity for 12 weeks. Twelve male Sprague-Dawley rats (aged 8 weeks, n=6 per group) were randomly assigned to a control group (CON) or a voluntary SPA group. The rats were induced to perform voluntary SPA (lifting a load equal to their body weight), while the food height (18.0 cm) in cages was increased progressively by 3.5 every 4 weeks until it reached 28.5 cm for 12 weeks. The SPA group showed a lower body weight compared to the CON group, but voluntary SPA did not affect the skeletal muscle and heart weights, food intake, and echocardiography results. Although the SPA group showed higher grip strength, running time, and distance compared to the CON group, the level of irisin, corticosterone, genetic expression of mitochondrial biogenesis, and nuclei numbers were not affected. These findings show that voluntary SPA without any forced stimuli in rats can eff ectively reduce body weight and enhance endurance exercise capacity, suggesting that it may be an important alternative strategy to enhance endurance exercise capacity.

Effect of hyperoxic training on endurance capacity and perfomance at sea level / 体力科学

The purpose of the present study was to clarify if hyperoxic training would be more effective on endurance capacity and performance at sea level than normoxic training.<BR>Twelve healthy males who had not been performing any regular endurance training participated in this study as subjects. They were divided into the two groups on the basis of their Vo<SUB>2</SUB>max ; one was the hyperoxic training group (Hyperoxic G) and the other was the normoxic training group (Normoxic G) . Training intensity of Hyperoxic G was 85% of Vo<SUB>2</SUB>max obtained breathing hyperoxia (a gas mixture of 60% O<SUB>2</SUB> in N<SUB>2</SUB>) . That of the Normoxic G was 85% of Vo<SUB>2</SUB>max obtained breathing room air. Duration of the daily training was 10 min in the former, and 10 min 22 sec to 11 min 30 sec in the latter ; thus, the amount of work was equal for both groups. Training frequency and period was 3 days/week and 4 weeks, respectively.<BR>After training, all-out time and lactate threshold in the Normoxic G was significantly enhanced from 17 min 18 sec to 19 min 7 sec and 19.6 m<I>l</I>/kg⋅min to 23.0 m<I>l</I>/kg⋅min. But, Vo<SUB>2</SUB>max, maximal ventilation and heart rate during training were not significantly changed. On the other hand, in the Hyperoxic G, not only all-out time and lactate threshold were significantly enhanced from 17 min 56 sec to 19 min 33 sec and 19.7 m<I>l</I>/kg⋅min to 24.9 m<I>l</I>/kg⋅min, but Vo<SUB>2</SUB>max and maximal ventilation were significantly increased from 46.1 m<I>l</I>/kg⋅min to 51.0 m<I>l</I>/kg⋅min and 117.3<I>l</I>/min to 135.1 <I>l</I>/min. Furthermore, heart rate during training was significantly decreased.<BR>From these results, it was concluded that hyperoxic training would be more effective in improving endurance capacity than normoxic training.