Arm-cranking exercises combined with electrical muscle stimulation (EMS) of the lower limbs at maximum intensity enhance vascular endothelial function. To bring this procedure into clinical application, we examined the effects of acute arm-cranking exercise combined with lower-extremity EMS at different intensities on vascular endothelial function. The study included eight healthy adult males. After resting in the supine position, arm-cranking exercises were performed at an intensity of 50% VO₂max for 20 min, and the lower limb received EMS under three trials: maximum intensity trial (A+100%EMS trial), 50% intensity trial (A+50%EMS trial), and 25% intensity trial (A+25%EMS trial). Flow-mediated dilation (FMD), which reflects vascular endothelial function, was measured before and after the procedure, and the normalized FMD (nFMD) was calculated. The mean nFMD before and 30 min after exercise was 0.8 ± 0.3 and 2.3 ± 1.8, respectively, in the A+100%EMS trial and 0.9 ± 0.4 and 1.4 ± 1.0, respectively, in the A+50%EMS trial, indicating a significant increase after exercise under both trials. No changes were observed in the A+25%EMS trial. The combination of arm-cranking exercise and 50% intensity EMS appears to be a clinically applicable program for improving vascular endothelial function, even with reduced exercise intensity.

The mitochondria are highly plastic organelles. Exercise training alters mitochondrial dynamics (mitochondrial fission and fusion) in skeletal muscles and improves overall mitochondrial function by altering mitochondrial morphology and forming new networks. However, changes in mitochondrial dynamics over time during exercise training have not previously been observed. In the present study, we examined the changes in mitochondrial fission and fusion protein expression in rats over four weeks of endurance swimming training. The expression of the GTPase protein dynamin-related protein 1 (Drp1), a mitochondrial fission protein, increased during the early phase of the training period. In contrast, the expression of optic atrophy type 1 (OPA1), a mitochondrial fusion protein, was increased in the late phase of the training period. These data suggest that mitochondrial fission was increased in the early phase, and mitochondrial fusion was initiated partially in the late phase, of the training period. In conclusion, mitochondrial dynamics may be modulated depending on the phase of muscular adaptation to exercise training. This modulation contributes to enhanced mitochondrial function in skeletal muscle.

Weight loss reduces visceral fat and improves glucose tolerance. Our previous study found that weight loss from 3 consecutive days of fasting led to deteriorated glucose tolerance, but it is not clear whether this was due either to the physiological stress associated with consecutive fasting or fasting itself. This study aimed to compare the effects of repetitive or consecutive fasting on intra-abdominal fat mass and glucose tolerance in rats fed a high-fat diet. After 2 weeks of high-fat diet feeding, male Wistar rats were divided into three groups matched for body weight: one group continued to receive the high-fat diet ad libitum for 2 weeks (control, CON); the second group fasted for the last 3 days (consecutive fasting, CF); and the third group repeated 1-day fasting three times with a 6-day ad libitum feeding interval (repetitive fasting, RF). Compared to the CON group, the intra-abdominal fat mass was significantly lower in the CF group after the intervention period, and there was a tendency for lower values in the RF group. During the oral glucose tolerance test, plasma glucose levels were significantly higher in both fasting groups compared to the CON group, while levels in the CF group were significantly higher than in the RF group. Compared to the CON group, the CF group had significantly lower plasma insulin levels, and slightly lower levels in the RF group. These findings suggest that even when fasting days are dispersed over multiple occasions, insulin secretion capacity may decrease in a similar manner to consecutive fasting, leading to a deterioration in glucose tolerance.