The objective of this study was to examine the effects of exercise training in hypoxia on arterial stiffness and flow-mediated vasodilation (FMD) in postmenopausal women. Sixteen postmenopausal women (56 ± 1 years) were assigned to a normoxic exercise group (Normoxic group, n = 8) or a hypoxic exercise group (Hypoxic group, n = 8). The Hypoxic group performed exercise under hypobaric hypoxic conditions corresponding to 2000 m above sea level, and was exposed to these conditions for 2 h per session. Aquatic exercise was performed at an intensity of around 50% peak oxygen uptake for 30 min, 4 days per week, for 8 weeks. Arterial stiffness was assessed by brachial–ankle pulse wave velocity (baPWV), and FMD was evaluated by peak diameter of the popliteal artery during reactive hyperemia. After the 8 weeks of training, the Normoxic group showed no significant changes. In contrast, baPWV (P < 0.05) was significantly reduced and peak diameter (P < 0.05) and %FMD (P < 0.01) were significantly increased in the Hypoxic group after training. These results suggest that exercise training under mild intermittent hypoxic conditions could more effectively reduce arterial stiffness in postmenopausal women, compared with exercise training performed at the same relative intensity under normoxic conditions. Our data also indicate that hypoxic exercise training may induce vascular functional adaptation, for example an increase in FMD response. These findings therefore could have important implications for the development of a new effective exercise prescription program.

Through pressure measurement, this study aimed to clarify the effects of hand paddle use on pressure and force generation around the hand during the front crawl. Eight male swimmers performed two trials of front crawl swimming with maximal effort, once using only their hands and once aided by hand paddles. During trials, pressure sensors and underwater motion capture cameras were used together to analyze hand kinematics and pressure forces acting on the hand. Six pressure sensors were attached to the right hand, and pressure forces acting on the right hand were estimated by multiplying the areas and the pressure differences between the palm side and dorsal side of the hand. Acting directions of pressure forces were analyzed using a normal vector perpendicular to the hand, calculated from coordinates of the right hand. As a result, using hand paddles decreases pressure differences between the palm and dorsal sides of hand related to the magnitude of pressure force. However, no difference was found in the mean value of resultant pressure forces compared with using hands alone, because the large surface area of the hand paddle compensated the decreased pressure differences due to decreased hand velocity. In addition, when hand paddles were used, the component of the pressure force acting in propulsive direction was significantly higher. Thus, the ratio of forces acting in the propulsive direction was higher than without hand paddles. These results suggest that the training loads with hand paddles are not high even if the swimming velocities increase because the power generated by upper limb motion didn't increase.

Effect of hand paddles on anaerobic energy release during supramaximal swimming. Med. Sci. Sports Exerc., Vol. 31, No. 5, pp. 729-735, 1999. Swimmers swim faster using hand paddles. In this study the effect of maximal performance using hand paddles on aerobic and anaerobic energy release during supramaximal swimming was examined by comparing the maximal accumulated O2 deficit, and the aerobic and anaerobic energy release during exhaustive swimming with paddles (P) to swimming without paddles (hands only, H). The subjects were six trained college male swimmers. Experiments were carried out in a swimming flume. The water flow rate was set before each exercise bout such that exhaustion occurred in 30 s, 1 min, or 2-3 min. Accumulated O2 deficit during exercise was determined by the accumulated oxygen demand minus the accumulated O2 uptake. Water flow rates at which maximal accumulated O2 deficit was obtained were significantly higher in P than that in H. However, mean values of maximal accumulated O2 deficit during H and P were 2.40 ± 0.42 L and 2.32 ± 0.37 L, respectively, and there was no significant difference between these two values. Furthermore, during the supramaximal swimming to exhaustion in 30 s, 1 min, or 2-3 min, both accumulated O2 uptake and accumulated O2 deficit did not significantly differ between these conditions, although mean water flow rates of these supramaximal swimming bouts were significantly higher in P than those in H again. These results suggest that the faster swimming speed accomplished with hand paddles does not affect metabolic responses and that it may be realized by recruitment of roughly the same muscle mass. Therefore, the ability to swim faster with hand paddles might mainly be attributed to other than metabolic factors, i.e., a higher propelling efficiency.

OGITA, F., R. P. STAM, H. O. TAZAWA, H. M. TOUSSAINT, and A. P. HOLLANDER. Oxygen uptake in one-legged and two-legged exercise. Med. Sci. Sports Exerc., Vol. 32, No. 10, pp. 1737–1742, 2000. The purpose of this study was to determine the primary factors causing the differential oxygen uptake (V̇O2) response at submaximal intensities between one-legged and two-legged exercise, and whether peak oxygen uptake (V̇O2peak) increases in proportion to the increase in active muscle mass. Two different types of exercise were used for this experiment, each requiring a different movement, a different method of stabilizing posture, and, finally, a different limiting V̇O2peak. In experiment 1, nine male subjects performed one-legged cycling (OLC) and two-legged cycling exercise (TLC) at a pedaling rate of 80 rpm. The exercise intensity was first set at 80 W and was increased by 40 W every 3 min until exhaustion. In experiment 2, six healthy male subjects performed one-legged knee-extension (OKE) and two-legged knee-extension (TKE) exercise at a rate of 50 contractions per minute. The knee-extension exercise was done at constant work rates for a 3-min session in OKE or a 4-min session in TKE. The exercise bouts were performed intermittently at four to seven different submaximal intensities and V̇O2 was determined at each intensity in all exercises. At submaximal intensities, V̇O2 in relation to work rate of one-legged exercise was more steep than those of two-legged exercise, and the mean values of V̇O2 were significantly higher in one-legged exercise than those in two-legged exercise in both knee extension and cycling exercise. Mean values of V̇O2peak for two-legged exercise were significantly higher than that for one-legged exercise (P < 0.01); however, it was much lower than two times of that for one-legged exercise even in knee extension exercise where the V̇O2peak would be limited peripherally. The findings of this study suggest that the differential V̇O2 response between one-legged and two-legged exercise would be attributed not only to the difference in force application throughout the exercise movement and to the effect of a postural component but also to the inhibited circulatory response caused by the multiple limb exercise. In addition, it was supposed that V̇O2peak does not increase in proportion to the exercising muscle mass even during smaller muscle activity where the cardiac pumping capacity has not reached its upper limit.