Vibration sensation associated with motor function has specific frequency characteristics in community-dwelling older Japanese adults / 体力科学

Vibration sensation is related to motor function. However, it is unclear which vibration frequencies are associated with motor function. Therefore, in this cross-sectional study, we investigated whether a specific frequency of vibration sensation could explain motor functions. Thirty-two community-dwelling Japanese healthy older adults aged 70 years or older participated in the present study. Grip strength, one-leg standing time, and 10-m walking time were evaluated as indicators of motor function. Vibratory (40, 128, and 256 Hz) and tactile sensory tests were examined as sensory functions. Grip strength per body weight was significantly correlated with sex, body mass index, falls efficacy scale, vibration sensation with 40 and 128 Hz, and 10-m walking time (P < 0.05). Furthermore, one-leg standing time showed a correlation between vibration sensation (128 and 256 Hz) and fall history (P < 0.05). However, 10-m walking time was significantly correlated with only the grip strength to body weight ratio. Multiple regression analysis showed that vibration sensation with 128 Hz (β = 0.427) and sex (β = -0.335) (P < 0.05) were significant independent variables associated with grip strength to body weight ratio. Vibration sensation with 256 Hz (β = 0.465) and age (β = -0.343) (P < 0.05) were significant independent variable associated with one-leg standing time. No significant variables were identified for the 10-m walking time. Vibration sensation associated with motor function shows specific frequency characteristics in community-dwelling older Japanese adults.

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.