The purpose of this investigation was to test whether the concept of critical power used in previous studies could be applied to the field of competitive swimming as critical swimming velocity (vcrit). The vcrit, defined as the swimming velocity over a very long period of time without exhaustion, was expressed as the slope of a straight line between swimming distance (dlim) at each speed (with six predetermined speeds) and the duration (tlim). Nine trained college swimmers underwent tests in a swimming flume to measure vcrit at those velocities until the onset of fatigue. A regression analysis of dlim on tlim calculated for each swimmer showed linear relationships (r2 greater than 0.998, P less than 0.01), and the slope coefficient signifying vcrit ranged from 1.062 to 1.262 m.s-1 with a mean of 1.166 (SD 0.052) m.s-1. Maximal oxygen consumption (VO2max), oxygen consumption (VO2) at anaerobic threshold, and the swimming also velocity at the onset of blood lactate accumulation (vOBLA) were also determined during the incremental swimming test. The vcrit showed significant positive correlations with VO2 at anaerobic threshold (r = 0.818, P less than 0.01), vOBLA (r = 0.949, P less than 0.01) and mean velocity of 400 m freestyle (r = 0.864, P less than 0.01). These data suggested that vcrit could be adopted as an index of endurance performance in competitive swimmers.

Flexibility is associated with arterial distensibility. Many individuals involved in sport, exercise, and/or fitness perform self-myofascial release (SMR) using a foam roller, which restores muscles, tendons, ligaments, fascia, and/or soft-tissue extensibility. However, the effect of SMR on arterial stiffness and vascular endothelial function using a foam roller is unknown. This study investigates the acute effect of SMR using a foam roller on arterial stiffness and vascular endothelial function. Ten healthy young adults performed SMR and control (CON) trials on separate days in a randomized controlled crossover fashion. Brachial-ankle pulse wave velocity (baPWV), blood pressure, heart rate, and plasma nitric oxide (NO) concentration were measured before and 30 minutes after both SMR and CON trials. The participants performed SMR of the adductor, hamstrings, quadriceps, iliotibial band, and trapezius. Pressure was self-adjusted during myofascial release by applying body weight to the roller and using the hands and feet to offset weight as required. The roller was placed under the target tissue area, and the body was moved back and forth across the roller. In the CON trial, SMR was not performed. The baPWV significantly decreased (from 1,202 ± 105 to 1,074 ± 110 cm·s-1) and the plasma NO concentration significantly increased (from 20.4 ± 6.9 to 34.4 ± 17.2 μmol·L-1) after SMR using a foam roller (both p < 0.05), but neither significantly differed after CON trials. These results indicate that SMR using a foam roller reduces arterial stiffness and improves vascular endothelial function.

It has been suggested that resistance training (RT) increases arterial stiffness. The purpose of the present study was to clarify the effect of eccentric RT (ERT) and concentric RT (CRT) on arterial stiffness in female adults by an interventional study. In total, 29 healthy female subjects were randomly assigned to either the ERT group (n ¼ 10), CRT group (n ¼ 10) or sedentary (SED) group (n ¼ 9). The ERT and CRT groups performed resistance training three times a week for 8 weeks. We determined brachial blood pressure, brachial-ankle pulse wave velocity (baPWV), carotid artery intimamedial thickness (IMT) and carotid arterial lumen diameter before and after training and after detraining.The before-training baPWV did not differ significantly among the three groups. After 8 weeks of RT, arterial stiffness in the CRT group was increased compared with the ERT and SED group (Po0.05). However, brachial blood pressure, baPWV, carotid IMT and carotid lumen diameter in the ERT and CRT groups were unchanged by RT for 8 weeks. Consequently, it was clarified that arterial stiffness was not changed by ERT for 8 weeks. This suggests that ERT may be effective as an exercise prescription for middle-aged and elderly adults.

The contributions and co-ordination of external finger grip forces were examined during a lifting task with a precision grip using multiple fingers. The subjects (n = 10) lifted a force transducer-equipped grip apparatus. Grip force from each of the five fingers was continuously measured under different object weight (200 g, 400 g and 800 g) and surface structure (plastic and sandpaper) conditions. The effect of five-, four-, and three-finger grip modes was also examined. It was found that variation of object weight or surface friction resulted in change of the total grip force magnitude; the largest change in finger force, was that for the index finger, followed by the middle, ring, and little fingers. Percentage contribution of static grip force to the total grip force for the index, middle, ring, and little fingers was 42.0%, 27.4%, 17.6% and 12.9%, respectively. These values were fairly constant for all object weight conditions, as well as for all surface friction conditions, suggesting that all individual finger force adjustments for light loads less than 800 g are controlled comprehensively simply by using a single common scaling value. A higher surface friction provided faster lifting initiation and required lesser grip force exertion, indicating advantageous effect of a non-slippery surface over a slippery surface. The results indicate that nearly 40% force reduction can be obtained when a non-slippery surface is used. Variation in grip mode changed the total grip force, i.e., the fewer the number of fingers, the greater the total grip force. The percent value of static grip force for the index, middle, and ring fingers in the four-finger grip mode was 42.7%, 32.5%, and 24.7%, respectively, and that for the index and middle fingers in the three-finger grip mode was 43.0% and 56.9%, respectively. Therefore, the grip mode was found to influence the force contributions of the middle and ring fingers, but not of the index finger.

Aerobic exercise training combined with resistance training (RT) might prevent the deterioration of vascular function. However, how aerobic exercise performed before or after a bout of RT affects vascular function is unknown. The present study investigates the effect of aerobic exercise before and after RT on vascular function. Thirty-three young, healthy subjects were randomly assigned to groups that ran before RT (BRT: 4 male, 7 female), ran after RT (ART: 4 male, 7 female), or remained sedentary (SED: 3 male, 8 female). The BRT and ART groups performed RT at 80% of one repetition maximum and ran at 60% of the targeted heart rate twice each week for 8 wk. Both brachial-ankle pulse wave velocity (baPWV) and flow-mediated dilation (FMD) after combined training in the BRT group did not change from baseline. In contrast, baPWV after combined training in the ART group reduced from baseline (from 1,025 +/- 43 to 910 +/- 33 cm/s, P < 0.01). Moreover, brachial artery FMD after combined training in the ART group increased from baseline (from 7.3 +/- 0.8 to 9.6 +/- 0.8%, P < 0.01). Brachial artery diameter, mean blood velocity, and blood flow in the BRT and ART groups after combined training increased from baseline (P < 0.05, P < 0.01, and P < 0.001, respectively). These values returned to the baseline during the detraining period. These values did not change in the SED group. These results suggest that although vascular function is not improved by aerobic exercise before RT, performing aerobic exercise thereafter can prevent the deteriorating of vascular function.

Although high-intensity resistance training increases central arterial stiffness, moderate-intensity resistance training does not. However, the effects of low-intensity resistance training on arterial stiffness are unknown. The aim of this study was to investigate the effect of low-intensity resistance training with short inter-set rest period (LSR) on arterial stiffness. Twenty-six young healthy subjects were randomly assigned to training (10 males, 3 females) and control groups (9 males, 4 females). The subjects performed LSR twice a week at 50% of one repetition maximum for 10 weeks. Training consisted of five sets of ten repetitions with an inter-set rest period of 30 s. Changes in brachial-ankle pulse wave velocity (baPWV) and brachial flow-mediated dilation (FMD) were assessed before and after the intervention period. After the intervention period, one repetition maximum strength increased (by 9-38%, P < 0.05 to <0.001; increases varied among the exercise types), baPWV decreased (from 1,093 ± 148 to 1,020 ± 128 cm/s, P < 0.05), and brachial FMD increased (from 9.7 ± 1.3 to 11.8 ± 1.9%, P < 0.05). These values did not change in the control group. These results suggest that LSR reduced arterial stiffness and improved vascular endothelial function.

Resistance training is widely recommended to prevent sarcopenia and osteoporosis. However, the effects of upper and lower limb resistance training on arterial stiffness are unclear. The present study investigates the effects of upper and lower limbs resistance training on arterial stiffness. Thirty young healthy subjects (male 19, female 11, aged 20.1 +/- 0.4 years, mean +/- SD) were randomly assigned to upper limb RT group (upper limb group, n = 10, male 7, female 3), lower limb RT group (lower limb group, n = 10, male 7, female 3) and sedentary groups (n = 10, male 6, female 4). The upper and lower limb groups performed RT at 80% of one repetition maximum twice each week for 10 weeks. Arterial stiffness was measured by brachial-ankle pulse wave velocity (baPWV). In addition, we measured plasma norepinephrine (NE) concentration. baPWV after training in the upper limb group had significantly increased from baseline (P < 0.05). In addition, plasma NE concentration after training in the upper limb group had significantly increased from baseline (P < 0.05). No such changes were observed in the lower limb and sedentary groups. Moreover, a significant positive correlation between baPWV and plasma NE concentration in upper limb group was observed (P < 0.05). In contrast, no significant correlation between baPWV and plasma NE concentration in lower limb and sedentary groups was observed. These findings suggested that upper limbs resistance training increases plasma NE concentration and promotes the increase of arterial stiffness.

Muscle contractions in normal resistance training are performed by eccentric (ECC, lowering phase) and concentric (CON, lifting phase) muscle contractions. However, the difference in effects of timing of muscle contraction during resistance training on arterial stiffness is unknown. This study investigated the effect of muscle contraction timing during resistance training on vascular function in healthy young adults. Thirty healthy men were randomly assigned to group of resistance training with quick lifting and slow lowering (ERT, n ¼ 10), group of resistance training with slow lifting and quick lowering (CRT, n ¼ 10) and sedentary groups (SED, n ¼ 10). The ERT and CRT groups underwent two supervised resistance-training sessions per week for 10 weeks. The ERT group performed the on set of 8-10 repetitions with 3 s ECC and 1 s CON muscle contractions. In contrast, the CRT group performed the on set of 8-10 repetitions with 1 s ECC and 3 s CON muscle contractions. Brachial-ankle pulse wave velocity (baPWV) after ERT did not change from baseline. In contrast, baPWV after CRT increased from baseline (from 1049 ± 37 to 1153±30 cm s À1 , Po0.05). No significant changes in flow-mediated dilation were observed in the ERT and CRT groups. These values did not change in the SED group. These findings suggest that although both training does not deteriorate a vascular endothelial function, resistance training with quick lifting and slow lowering (that is, ERT) prevent the stiffening of arterial stiffness.