Femoral bone structure in Otsuka Long-Evans Tokushima Fatty rats

OBJECTIVES: Type 2 diabetes mellitus (T2DM) increases fracture risk despite normal to high levels of bone mineral density. Bone quality is known to affect bone fragility in T2DM. The aim of this study was to clarify the trabecular bone microstructure and cortical bone geometry of the femur in T2DM model rats. METHODS: Five-week-old Otsuka Long-Evans Tokushima Fatty (OLETF; n = 5) and Long-Evans Tokushima Otsuka (LETO; n = 5) rats were used. At the age of 18 months, femurs were scanned with micro-computed tomography, and trabecular bone microstructure and cortical bone geometry were analyzed. RESULTS: Trabecular bone microstructure and cortical bone geometry deteriorated in the femur in OLETF rats. Compared with in LETO rats, in OLETF rats, bone volume fraction, trabecular number and connectivity density decreased, and trabecular space significantly increased. Moreover, in OLETF rats, cortical bone volume and section area decreased, and medullary volume significantly increased. CONCLUSIONS: Long-term T2DM leaded to deterioration in trabecular and cortical bone structure. Therefore, OLETF rats may serve as a useful animal model for investigating the relationship between T2DM and bone quality.

Relationship between the habitual physical activity and the balancing ability against abrupt acceleration disturbance in elderly females / 体力科学

The purpose of this study was to examine the relationship between balancing ability during abrupt acceleration and the habitual physical activity level of elderly females. Thirty-one elderly females, aged 65-75 years, volunteered for this study. Changes in the center of foot pressure (CFP) were measured during postural sway following platform acceleration, and the response time and CFP displacement were evaluated. The scores of their daily physical activities (TS) -consisting of house-hold activities (HS), leisure time activities (LS) and sports activities (SS) -were estimated by the modified Voorrips's questionaire method. Response time and CFP displacement correlated significantly with age (p<0.001) . Response time also correlated significantly with the SS, LS and TS scores (p<0.05) . CFP displacement also correlated significantly with the SS and TS scores (p<0.05) . These results suggest that postural balancing ability during abrupt acceleration correlates signifi-cantly with the habitual physical activity levels, especially sports activities in elderly females.

Determination of anaerobic threshold in the elderly using integrated electromyographic signals / 体力科学

A study was conducted to examine the feasibility and validity of using integrated electromyographic signals (IEMG) for determination of anaerobic threshold (AT) in the elderly. Twentynine healthy elderly subjects (aged 67.6±7.7 yr) and twelve young males (aged 23.2±7.9 yr) performed ramp cycle exercise to exhaustion, increasing at a rate of 12.5 W/min for the elderly group and 25.0 W/min for the young group, following 3 min of exercise at zero work load. Myoelectrical signals were measured continuously from the vastus lateralis muscle, and values in terms of IEMG were computed every 10s throughout the test with AID conversion at 500 Hz. For the criterion of IEMG threshold, the breakpoint in the relationship between power output and IEMG was determined by two-segmental linear regression. VT was defined as the VO<SUB>2</SUB> at the onset of a nonlinear increase in VE and/or a sustained rise in VE/VO<SUB>2</SUB> without a rise in VE/VCO<SUB>2</SUB>. It was found that the value of VO<SUB>2</SUB> in terms of IEMGT was similar to VT in both groups, 16.3 and 18.1 ml/kg/min for the elderly group and 33.5 and 36.3 ml/kg/min for the young group, respectively. Furthermore, IEMGT was correlated significantly (p<0.001) with VT in both groups (r=0.871 for the elderly group and r=0.925 for the young group) . It is concluded that the IEMGT method for determination of AT in the elderly is simple and useful.