PurposeArterial stiffness might be related to trunk flexibility in middle-aged and older participants, but it is also affected by age, sex, and blood pressure. This cross-sectional observational study investigated whether trunk flexibility is related to arterial stiffness after considering the major confounding factors of age, sex, and blood pressure. We further investigated whether a simple diagnostic test of flexibility could be helpful to screen for increased arterial stiffening.MethodsAccording to age and sex, we assigned 1150 adults (male, n = 536; female, n = 614; age, 18–89 y) to groups with either high- or poor-flexibility based on the sit-and-reach test. Arterial stiffness was assessed by cardio-ankle vascular index.ResultsIn all categories of men and in older women, arterial stiffness was higher in poor-flexibility than in high-flexibility (P<0.05). This difference remained significant after normalizing arterial stiffness for confounding factors such as blood pressure, but it was not found among young and middle-aged women. Stepwise multiple-regression analysis also supported the notion of the sex differences in flexibility-arterial stiffness relationship. Receiver operating characteristic curve analysis revealed that cut-off values for sit-and-reach among men and women were 33.2 (area under the curve [AUC], 0.711; 95% confidence interval [CI], 0.666–0.756; sensitivity, 61.7%; specificity, 69.7%) and 39.2 (AUC, 0.639; 95% CI, 0.592–0.686; sensitivity, 61.1%; specificity, 62.0%) cm, respectively.ConclusionOur results indicate that flexibility-arterial stiffness relationship is not affected by BP, which is a major confounding factor. In addition, sex differences are observed in this relationship; poor trunk flexibility increases arterial stiffness in young, middle-aged, and older men, whereas the relationship in women is found only in the elderly. Also, the sit-and-reach test can offer a simple method of predicting arterial stiffness at home or elsewhere.

Trunk flexibility may be associated with arterial stiffness in young, middle-aged, and older healthy men after adjusting for blood pressure. This study assessed the effects of 4 weeks of regular static stretching on arterial stiffness in middle-aged men. Sixteen healthy men (43 ± 3 years) were assigned to control or intervention groups (n = 8 each). The control group did not alter their physical activity levels throughout the study period. The intervention group participated in five supervised stretching sessions per week for 4 weeks. Each session comprised 30 min of mild stretching that moved the major muscle groups through the full range of motion and stretches were held three times for 20 s at the end range. Flexibility was assessed by sit-and-reach test. Arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV) and cardio-ankle vascular index (CAVI). Four weeks of stretching increased sit-and-reach (Control, Pre: 31.4 ± 2.1, Post: 30.8 ± 2.7 vs. Intervention, Pre: 30.6 ± 5.3, Post: 43.9 ± 4.3 cm), and reduced baPWV (Control, Pre: 1204 ± 25, Post: 1205 ± 38 vs. Intervention, Pre: 1207 ± 28, Post: 1145 ± 19 cm/s) and CAVI (Control, Pre: 7.6 ± 0.3, Post: 7.5 ± 0.3 vs. Intervention, Pre: 7.7 ± 0.2, Post: 7.2 ± 0.2 units) in the intervention group. However, the change in sit-and-reach did not significantly correlate with the changes in arterial stiffness. These findings suggest that short-term regular stretching induces a significant reduction in arterial stiffness in middle-aged men.

It has been reported that exercise under hypoxic conditions elevates acute growth hormone secretion after exercise compared with that under normoxic conditions. This study examined the influence of resistance training under moderate hypoxic conditions on muscle thickness, strength and hormonal responses. Thirteen healthy men were assigned into two groups matched for physical fitness level and then randomized into two groups that performed exercise under normoxic (FiO2  = 20·9%) or hypoxic (FiO2  = 12·7%) conditions. Three sets of elbow extensions with unilateral arm were performed to exhaustion at a workload of a 10 repetition maximum with 1-minute intervals for 3 days per week for 8 weeks. The thickness of the biceps and triceps brachii was determined using B-mode ultrasound before and after training. Blood sampling was carried out before and after exercise, as well as during the first and last training sessions. Increase in the thickness of the triceps brachii in trained arm was significantly greater in the hypoxic group than in the normoxic group. The 10 repetition maximum was significantly increased not only in the trained arm but also in the untrained arm in both groups. Serum growth hormone concentrations after exercise were significantly higher in the hypoxic group than in the normoxic group on both the first and last training sessions. These findings suggest that hypoxic resistance training elicits more muscle hypertrophy associated with a higher growth hormone secretion, but that the greater muscle hypertrophy did not necessarily contribute a greater gain of muscle strength.

Previous studies reported that aerobic-type exercise such as walking or cycling with blood flow restriction (BFR) has been shown to elicit increases in leg muscle hypertrophy and strength, as well as improved aerobic capacity. Although previous studies investigated cardiovascular responses during a relatively short duration of exercise (∼5 min), the effects of prolonged leg muscular BFR have remained unknown. The purpose of this study was to examine the cardiovascular effects of longer duration low intensity exercise combined with BFR. Eight men performed 30 min of exercise at 40% of a predetermined maximal oxygen uptake under both BFR and normal flow (CON) conditions. Cardiovascular parameters were measured at rest and every 10 min during exercise. The main findings were that 1) the SV and HR did not change significantly between 10 to 30 min of exercise in BFR and CON conditions, although BFR-induced reduction of SV and increased HR were found at 10 min exercise compared with normal flow, 2) blood pressure was increased at 10 min of exercise in BFR compared to the CON, however the blood pressure decreased gradually with BFR from 10 to 30 min of exercise, and 3) blood lactate and RPE increased gradually during exercise with BFR. In conclusion, our results suggest that the BFR-induced reduction of SV and increased HR within the first 10 min of exercise are representative of changes in these parameters.

We investigated the effect of the combination of coffee ingestion and repeated bouts of low-intensity exercise on fat oxidation. Subjects were seven young, healthy male adults. They performed four trials: a single 30-min bout of exercise following ingestion of plain hot water (WS) or coffee (CS); a trial with three 10-min bouts of exercise separated by 10-min periods of rest following ingestion of plain hot water (WR) or coffee (CR). The coffee contained 5 mg kg of caffeine. All trials were performed on a cycle ergometer at 40% maximal oxygen uptake for each subject an hour after beverage ingestion. Oxygen uptake in the CS and CR trials was higher compared with the WS and WR trials at 90 min after exercise (P<0·05). Respiratory exchange ratio (RER) in the CS and CR trials was decreased during the whole recovery period compared with baseline (P<0·05), whereas no significant decreases were observed in either the WS or WR trials. Moreover, RER was significantly lower at 30 min after exercise in the CR trial than in either the WS or WR trials (P<0·05 each). Similarly, it is notable that fat oxidation rate in the CR trial was significantly higher at 30 min after exercise compared to that in the WS and WR trials (P<0·05). These results suggest that the combination of coffee intake and repeated bouts of low-intensity exercise enhances fat oxidation in the period after exercise.