Habitual moderate-to-vigorous–intensity physical activity attenuates arterial stiffening. However, it is unclear whether light physical activity also attenuates arterial stiffening. It is also unclear whether light physical activity has the same effects in fit and unfit individuals. This cross-sectional study was performed to determine the relationships between amount of light physical activity determined with a triaxial accelerometer and arterial stiffness. A total of 538 healthy men and women participated in this study. Subjects in each age category were divided into either high-light or low-light physical activity groups based on daily time spent in light physical activity. Arterial stiffness was measured by carotid-femoral pulse wave velocity. Two-way ANOVA indicated a significant interaction between age and time spent in light physical activity in determining carotid-femoral pulse wave velocity ( P <0.05). In the older group, carotid femoral pulse wave velocity was higher in the low-light physical activity level group than in the high-light physical activity level group (945±19 versus 882±16 cm/s; P <0.01). The difference remained significant after normalizing carotid-femoral pulse wave velocity for amounts of moderate and vigorous physical activity. The carotid-femoral pulse wave velocity ( r =−0.47; P <0.01) was correlated with daily time spent in light physical activity in older unfit subjects. No relationship was observed in older fit subjects. These results suggested that longer time spent in light physical activity is associated with attenuation of arterial stiffening, especially in unfit older people.

To elucidate the effects of endurance training on circulating irisin levels in young and middle-aged/older adults, and to determine the association between endurance training-induced alteration of irisin and reduction in body fat. Twenty-five healthy young (age 21 ± 1 years; 16 men, 9 women) and 28 healthy middle-aged/older adults (age 67 ± 8 years; 12 men, 16 women) participated in the study. Each age cohort was divided into two groups: the endurance-training group (14 young, 14 middle-aged/older) and the control group. Subjects in the training groups completed an 8-week endurance-training program (cycling at 60-70% peak oxygen uptake [ O_2peak] for 45 min, 3 days/week). Before and after the intervention, we evaluated serum irisin level, O_2peak, and body composition. The increase in O_2peak in the young and middle-aged/older training groups after the intervention period was significantly greater than those in the young and middle-aged/older control groups (P < 0.05). Serum irisin level was significantly increased in the middle-aged/older training group after the intervention period (P < 0.01), but not in the young training group. Furthermore, in the middle-aged/older training group, the endurance training-induced reduction in visceral adipose tissue area was negatively correlated with the change in serum irisin level (r = −0.54, P < 0.05). These results suggest a possible role for secreted irisin in the exercise-induced alteration of abdominal visceral fat in middle-aged and older adults.

Flexibility is one of the components of physical fitness as well as cardiorespiratory fitness and muscular strength and endurance. Flexibility has long been considered a major component in the preventive treatment of musculotendinous strains. The present study investigated a new aspect of flexibility. Using a cross-sectional study design, we tested the hypothesis that a less flexible body would have arterial stiffening. A total of 526 adults, 20 to 39 yr of age (young), 40 to 59 yr of age (middle-aged), and 60 to 83 yr of age (older), participated in this study. Subjects in each age category were divided into either poor- or high-flexibility groups on the basis of a sit-and-reach test. Arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV). Two-way ANOVA indicated a significant interaction between age and flexibility in determining baPWV ( P < 0.01). In middle-aged and older subjects, baPWV was higher in poor-flexibility than in high-flexibility groups (middle-aged, 1,260 ± 141 vs. 1,200 ± 124 cm/s, P < 0.01; and older, 1,485 ± 224 vs. 1,384 ± 199 cm/s, P < 0.01). In young subjects, there was no significant difference between the two flexibility groups. A stepwise multiple-regression analysis ( n = 316) revealed that among the components of fitness (cardiorespiratory fitness, muscular strength, and flexibility) and age, all components and age were independent correlates of baPWV. These findings suggest that flexibility may be a predictor of arterial stiffening, independent of other components of fitness.