Yusuke Osawa

Relationships of Muscle Echo Intensity with Walking Ability and Physical Activity in the Very Old Population

This study investigated the relationships between muscle echo intensity (EI), physical activity (PA), and functional mobility in 108 Japanese (88-92 years). We measured EI and muscle thickness (MT) at the midpoint of the anterior superior iliac spine and patella using B-mode ultrasound. Light and moderate-to-vigorous PA (LPA and MVPA) were assessed with a triaxial accelerometer. The timed up and go (TUG) test was used to measure for functional mobility. EI, but not MT, was significantly associated with both TUG scores (β = 0.17, p = .047) and MVPA (β = -0.31, p = .01) when adjusted by potential confounders. However, association between EI and TUG disappeared after adjusted for MVPA. Meanwhile, MVPA was significantly associated with TUG scores independent of EI (β = -0.35, p < .001). Although EI of anterior thigh muscles might be a weaker predictor of functional morbidity than MVPA, it is a noninvasive and practical approach for assessing muscle quality in the very old.

Effects of combining whole-body vibration with exercise on the consequences of detraining on muscle performance in untrained adults

Abstract Osawa, Y and Oguma, Y. Effects of combining whole-body vibration with exercise on the consequences of detraining on muscle performance in untrained adults. J Strength Cond Res 27(4): 1074–1082, 2013—This study investigated whether whole-body vibration (WBV) coupled with low-velocity exercise (EX) for 13 weeks retains muscle performance gains after 5 weeks of subsequent detraining compared with the results of an identical EX program without WBV. Thirty-two untrained healthy adults (22–49 years of age) were randomly assigned to groups that performed EX with or without WBV (EX-WBV and EX, respectively; n = 16 per group). The following outcome variables were evaluated: countermovement jump height; maximal isometric, concentric, and eccentric knee extension strengths; local muscular endurance; and lumbar extension torque before, during, and after the 13-week training period, and after 5 weeks of detraining. Compared with the EX group, significantly higher increases in countermovement jump height and isometric and concentric knee extension strengths were detected in the EX-WBV group after the 13-week training period. However, detraining caused significant declines in these 3 muscle performance tests only in the EX-WBV group (−4.8, −10.2, and −17.2%, respectively), resulting in no significant differences between the test and control groups after the detraining period. After detraining, all examined variables showed significantly better performance compared with pretraining (p < 0.05) and did not significantly differ from midtraining (7 weeks) in both groups (p > 0.05). These results suggest that muscle strength in the lower extremities, particularly isometric and concentric contractions, and muscle power might be more susceptible to short-term detraining effects when exercise is combined with WBV. Thus, it is necessary to perform regular exercise to maximize the benefits of WBV on muscle strength and power during the early stages of training in previously untrained individuals.

Validation of Questionnaire-Assessed Physical Activity in Comparison With Objective Measures Using Accelerometers and Physical Performance Measures Among Community-Dwelling Adults Aged ≥85 Years in Tokyo, Japan

BACKGROUND To date, there is no physical activity (PA) questionnaire with convergent and construct validity for the oldest-old. The aim of the current study was to investigate the validity of questionnaire-assessed PA in comparison with objective measures determined by uniaxial and triaxial accelerometers and physical performance measures in the oldest-old. METHODS Participants were 155 elderly (mean age 90 years) who were examined at the university and agreed to wear an accelerometer for 7 days in the 3-year-follow-up survey of the Tokyo Oldest-Old Survey of Total Health. Fifty-nine participants wore a uniaxial and triaxial accelerometer simultaneously. Self-rated walking, exercise, and household PA were measured using a modified Zutphen PA Questionnaire (PAQ). Several physical performance tests were done, and the associations among PAQ, accelerometer-assessed PA, and physical performances were compared by Spearmans correlation coefficients. RESULTS Significant, low to moderate correlations between PA measures were seen on questionnaire and accelerometer assessments (ρ = 0.19 to 0.34). Questionnaireassessed PA measure were correlated with a range of lower extremity performance (ρ = 0.21 to 0.29). CONCLUSIONS This PAQ demonstrated convergent and construct validity. Our findings suggest that the PAQ can reasonably be used in this oldest-old population to rank their PA level.

Knee extension rate of torque development and peak torque: associations with lower extremity function: Rate of torque development and lower extremity function

With aging, the ability to generate muscle force decreases, contributing to declines in physical functions such as walking. While most studies assess muscle force by peak torque, the rate of torque development (RTD) reflects a dynamic component of muscle performance that is important for physical function. Using data from the Baltimore Longitudinal Study of Aging, we assessed whether RTD adds significantly to peak torque in associations with lower extremity performance. If so, RTD may help identify weak older adults for screening and intervention.