BackgroundToe flexor muscles play an important role in posture and locomotion, and poor toe flexor strength is a risk factor for falls. In this cross-sectional study, we estimated the age-related change in toe flexor strength and compared it with that of handgrip strength. Independent factors predicting toe flexor and handgrip strength were also determined.MethodsA total of 1401 male (aged 35–59 years) study participants were divided into five groups according to their chronological age; 35–39, 40–44, 45–49, 50–54, and 55–59 years. Toe flexor and handgrip strength, anthropometry, and resting blood pressure were measured. Fasting blood samples were collected to measure blood glucose, triglycerides, high- and low-density lipoprotein-cholesterols, and albumin. A self-administered lifestyle questionnaire was conducted.ResultsDecline in absolute toe flexor and handgrip strength began in the age groups 50–55 and 55–59 years, respectively. In comparison to the mean values of the youngest group, relative toe flexor strength (87.0 ± 26.6%) was significantly lower than handgrip strength (94.4 ± 13.1%) for the oldest group. Multiple regression analyses showed that independent factors predicting both toe flexor and handgrip strength were lean body mass, age, serum albumin, drinking habit, and fat mass. Additionally, fasting blood glucose, diastolic blood pressure, sleeping time and exercise habit were predicting factors of toe flexor strength but not of handgrip strength.ConclusionsAge-related reduction in toe flexor strength was earlier and greater than handgrip strength, and toe flexor strength reflects body composition and metabolic status.

[Purpose] To compare the toe flexor, hand grip and knee extensor strengths of young and elderly men, and to examine the association between toe flexor strength and physical activity or inactivity levels. [Subjects and Methods] Young (n=155, 18–23 years) and elderly (n=60, 65–88 years) men participated in this study. Toe flexor, hand grip, and knee extensor strength were measured. Physical activity (time spent standing/walking per day) and inactivity (time spent sitting per day) were assessed using a self-administered questionnaire. [Results] Toe flexor, hand grip, and knee extensor strength of the elderly men were significantly lower than those of the young men. Standing/walking and sitting times of the elderly men were lower than those of the young men. Toe flexor strength correlated with hand grip and knee extensor strength in both groups. In elderly men, toe flexor strength correlated with standing/walking time. In comparison to the young men’s mean values, toe flexor strength was significantly lower than knee extensor and hand grip strength in the elderly group. [Conclusion] The results suggest that age-related reduction in toe flexor strength is greater than those of hand grip and knee extensor strengths. An early loss of toe flexor strength is likely associated with reduced physical activity in elderly men.

ObjectiveThis study examined the associations of body flexibility with carotid arterial remodelling, including intima–media thickness (IMT) and plaque formation in middle-aged men.MethodsThe subjects of this cross-sectional study included 1354 Japanese men aged 35–59 years without histories of stroke or cardiac diseases. The arm extensibility test, which can estimate flexibility of the upper extremity (composed of shoulder external rotation and forearm supination), and the sit-and-reach test were performed. Common carotid IMT and plaque formation (≥1.1 mm) were estimated by ultrasound.ResultsThe proportion of subjects who fully completed the arm extensibility test was 55.0%, and who had plaques in the common carotid artery was 37.8%. IMT was associated with poor arm extensibility (β=–0.073, 95% CI –0.02224 to –0.00041, P=0.004), while plaque formation was associated with poor sit-and-reach (OR 0.98579, 95% CI 0.97257 to 0.99919, P=0.038) after adjustment by all covariates.ConclusionsThis study demonstrated that poor upper extremity and trunk flexibility were associated with characteristics of early onset of atherosclerosis. Furthermore, these associations were independent of covariates such as age, blood pressure, blood lipids glucose levels and abdominal fat accumulation, handgrip strength and lifestyle, including sleeping, drinking, exercise and smoking habits. Poor flexibility may reflect subclinical atherosclerosis in middle-aged men.

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The purpose of this study was to investigate whether long-term wheel running would attenuate age-related loss of muscle fiber. Male ICR mice were divided into young (Y, n=12, aged 3 months), old-sedentary (OS, n=5, aged 24 months), and old-exercise (OE, n=6, aged 24 months) groups. The OE group started spontaneous wheel running at 3 months and continued until 24 months of age. Soleus and plantaris muscles were fixed in 4% paraformaldehyde buffer. The fixed muscle was digested in a 50% NaOH solution to isolate single fiber and then fiber number was quantified. The masses of the soleus and plantaris muscles were significantly lower at 24 months than at 3 months of age, and this age-related difference was attenuated by wheel running (P<0.05). Soleus muscle fiber number did not differ among the groups. In the plantaris muscle, the fiber number in the OS group (1 288±92 fibers) was significantly lower than in the Y group (1 874±93 fibers), and this decrease was attenuated in the OE group (1 591±80 fibers) (P<0.05). These results suggest that age-related fiber loss occurs only in the fast-twitch fiber-rich muscle of mice, and that life-long wheel running exercise can prevent this fiber loss.