RESUMEN
Thirty (n=30) seven week old male Sprague-Dawley rats were divided into six groups of five rats (n=5) in each group. The groups were designated Sc=sea level controls; St=sea level trained; Fc=hypoxic exposed (16% O<SUB>2</SUB>) controls; Ft =hypoxic exposed (16% O<SUB>2</SUB>) trained; Pc=intermittent hypoxic exposed (18%, 16%, 14%, 16%, 18% O<SUB>2</SUB> for two days each) controls; and Pt=intermittent hypoxic exercise trained. Exercise training consisted of 45min/day running on a rat treadwheel for 24 consecutive days. Fiber type distribution, succinate dehydrogenase (SDH) activity and glycogen content of the soleus muscle and the oxidative enzyme activity of the motoneurons of the soleus were measured in each group after the 24 days of hypoxic exposure and exercise training. In comparison to each training group's control the glycogen concentration of the soleus muscle was increased (P<0.05) regardless of hypoxic exposure. Only the intermittently hypoxic exercise trained group (Pt) demonstrated a fiber type shift of slow-twitch oxidative to fast-twitch oxidative glycolytic fibers. Neither hypoxia or exercise training altered the oxidative enzyme capacity of the soleus motoneurons.
RESUMEN
The purpose of this study was to clarify some of the characteristics of race-walking, especially the relationship between walking speed and oxygen requirement, and stride in race-walking and normal walking, and to examine whether race-walking is effective for the maintenance and promotion of health.<BR>The subjects were five male race-walkers (race-walker group) and five male college students (control group) .<BR>The results obtained were as follows:<BR>1. Under race-walk conditions, the highest speeds attained in the race-walker and control groups were 200-220 m/min and 160 m/min, respectively. Under normal walking conditions, however, the values were 140 m/min in both groups.<BR>2. A lower oxygen requirement was observed at slower speed during normal walking and at a higher speed (over 130 m/min) during race-walking.<BR>3. Oxygen requirement (ml/kg/100 m) in the race-walker group was minimal at 60-80 m/min during race-walking and at 60 m/min during normal walking. Values in the control group were minimal at 60 m/min under both walking conditions.<BR>4. The oxygen requirement in the race-walker group was less than that of the control group under both walking conditions.<BR>5. Under normal walking conditions, as the speed increased, both step-length and step frequency gradually increased, until step-length reached a limit of 80 cm. Thereafter, walking was maintained only by an increase in step frequency. However, in the race-walkes group, the subjects were capable of increasing their step-length further, and maintaining a higher speed (up to 220 m/min) .<BR>6. It was suggested that race-walking is one of the most efficient exercises for maintaining and improving health.
RESUMEN
The purpose of this study was to clarify some of the characteristics of race-walking, especially the relationship between walking speed and oxygen requirement, and stride in race-walking and normal walking, and to examine whether race-walking is effective for the maintenance and promotion of health.<BR>The subjects were five male race-walkers (race-walker group) and five male college students (control group) .<BR>The results obtained were as follows:<BR>1. Under race-walk conditions, the highest speeds attained in the race-walker and control groups were 200-220 m/min and 160 m/min, respectively. Under normal walking conditions, however, the values were 140 m/min in both groups.<BR>2. A lower oxygen requirement was observed at slower speed during normal walking and at a higher speed (over 130 m/min) during race-walking.<BR>3. Oxygen requirement (ml/kg/100 m) in the race-walker group was minimal at 60-80 m/min during race-walking and at 60 m/min during normal walking. Values in the control group were minimal at 60 m/min under both walking conditions.<BR>4. The oxygen requirement in the race-walker group was less than that of the control group under both walking conditions.<BR>5. Under normal walking conditions, as the speed increased, both step-length and step frequency gradually increased, until step-length reached a limit of 80 cm. Thereafter, walking was maintained only by an increase in step frequency. However, in the race-walkes group, the subjects were capable of increasing their step-length further, and maintaining a higher speed (up to 220 m/min) .<BR>6. It was suggested that race-walking is one of the most efficient exercises for maintaining and improving health.
