A comparison of aerobic capacity in long-distance runners and triathletes with the same level of running performance / 体力科学

The purpose of this study was to clarify the aerobic fitness of triathletes comparing with long-distance runners with the same level of running performance. Thirteen male university endurance athletes were divided into two groups ; long-distance runners and triathletes. The subjects performed maximal and submaximal treadmill running test to assess their maximal oxygen uptake (VO2max) and running economy (RE). The VO2max (ml/kg/min) in triathletes was lower than that in the runners (p = 0.08, d = 1.18). The RE (ml/kg/km) in triathletes was higher than that in the runners (p = 0.05, d = 1.34). This study suggests that the difference of aerobic fitness between two homogeneous groups is caused by running form and the training with preceding exercise.

Development of a physical fitness evaluation method that accounts for individual growth status in 6-17 year old students using data obtained in 2009 / 体力科学

Evaluation of the physical fitness level of children and adolescents must include consideration of individual growth rates. This study evaluates the relationship between height and physical fitness in a large sample of 6-17 yr students. Physical fitness test scores were calculated for every 1 cm height group and used to generate quadratic regression equations. Physical fitness data reported by the Ministry of Education, Culture, Sports, Science and Technology in Japan (MEXT) were compared with estimated values obtained using our regression equations. The differences between the values reported by MEXT and our estimated values were very small. Comparison of physical fitness T-scores calculated based on school grade averages with T-scores based on means calculated using our regression equations indicated that shorter height students had lower T-scores if school grade averages were used for the calculation. In conclusion, in elementary and junior high school students, it is important to evaluate physical fitness level relative to individual physical growth.

EFFECTS OF ECCENTRIC CONTRACTIONS ON IN VITRO Na⁺-K⁺-ATPase ACTIVITY AND SARCOPLASMIC RETICULUM Ca²⁺-SEQUESTERING IN RAT SKELETAL MUSCLE / 体力科学

The purpose of this study was to examine the effects of eccentric contractions (Ecc) on cation (i.e., K⁺, Na⁺ and Ca²⁺) regulation in skeletal muscle. The left anterior crural muscles of male Wistar rats were subjected <i>in vivo</i> to either Ecc or isometric contrations (Iso) for 200 cycles. The extensor digitorum longus and tibialis anterior muscles were removed immediately after and 2, 4 and 6 days following contractions and used for measures of force output and biochemical analyses, respectively. Ecc led to a 75% decrease in maximal tetanic force. Decreased force output did not revert to pre-exercise levels during 6 days of recovery. Sarcoplasmic reticulum (SR) Ca²⁺-ATPase activity was reduced by 52 and 60% 4 and 6 days after Ecc, respectively. The reduction in catalytic activity after 6 days was accompanied by a 63% decrease in SR Ca²⁺-ATPase protein and an approximately 3.5-fold increase in calpain activity. Na⁺-K⁺-ATPase acticity was decreased by 23% immediately after Ecc and restored during 2 days of recovery. These alterations were specific for Ecc and not observed for Iso. These results suggest that disturbances in cation regulation may account, at least partly, for Ecc-induced decreases in force and power which can take a number of days to recover and that the decrease in SR Ca²⁺-ATPase activity would result from the degradation of the enzyme.

Comparison of walking patterns of young and elderly men with a special reference to the characteristics of the lower leg movement / 体力科学

The purpose of this study was to clarify the characteristics of the gait function for the elderly with a special reference to the angle of the ankle joint and that of the metatarsophalangeal (MP) joint at heel contact and toe off. Five healthy young men (aged 22 to 23 yrs) and five healthy elderly men (aged 65 to 71 yrs) participated as the subjects in this study. The angle variation of the right ankle joint and that of the MP joint detected in goniometers were analyzed synchronously with the data of the force plate and the image data of bare foot movements during free, slow, and fast gait. The following results were obtained:<BR>1. The walking speed, step length, and cadence for the elderly during free gait were significantly small. Furthermore, the step length of the elderly was shorter than that of the younger subject even with the same height. Moreover, it was found that the fluctuation in both the step length and cadence resulted in an fluctuation in walking speed.<BR>2. One reason for the decrease in step length and cadence, and the increase in duration of the double supporting time for the elderly is the lowering of walking speed.<BR>3. The angle of the ankle at heel contact, the angle of the ankle at toe off, and the angular displacement of the MP joint were significantly smaller for the elderly during free gait and during walking within a range of speeds. Also, the angle of the ankle at heel contact, and the angle of the ankle at toe off for young and elderly subjects were separated into two groups during walking within a range of speeds. It may be showed that the reason for the smallness of the angle of the ankle at heel contact and the angle of the ankle at toe off for the elderly irrespective of walking speed is due to an elderly behavior that unconsciously makes the angle smaller to prevent the danger of falling.<BR>In conclusion, the difference in variables between young and elderly subjects during free gait and walking within a range of speeds exemplifies the characteristics of gait function for the elderly.