The purpose of this study was to determine whether oxygenation in localized working muscle depended on the muscle activity and on the lactic acidosis level. Seven healthy male subjects underwent the five 6-min cycling exercises with work rates of 50 watts (25.0 +/- 5.0% VO2max), 100 watts (36.6 +/- 6.2% VO2max), 150 watts (50.6 +/- 7.7% VO2max), 200 watts (67.8 + 6.9% VO2max), and 250 watts (82.9 +/- 7.5% VO2max) while gas exchange parameters and blood lactate concentration (BL) were measured. We also measured oxygenated hemoglobin and myoglobin concentration (oxy-Hb/Mb) with continuous-wave near infrared spectroscopy (NIR) and surface myoelectric activity with surface electrodes (EMG). The NIR probe and electrodes were positioned on the vastus lateralis muscle of the right leg. The relative change in oxy-Hb/Mb was estimated by regarding oxy-Hb/Mb in the resting condition as 100% and that obtained during thigh occlusion as 0%. The mean values of oxy-Hb/Mb and integrated EMG (iEMG) were determined from 5'30" to 6'00" at each work rate. The percentage of oxy-Hb/Mb was sustained at the first two work rates corresponding to 25.0 +/- 5.0 and 36.6 +/- 6.2% VO2max and decreased slightly at 150 watts corresponding to 50.6 +/- 7.7% VO2max, which was followed by a linear decrease at 200 and 250 watts corresponding to 67.8 +/- 6.9 and 82.9 +/- 7.5% VO2max. The iEMG, however, was increased slowly at 25.0 +/- 5.0 to 50.6 +/- 7.7% VO2max, and a rapid increment of the iEMG occurred at 67.8 +/- 6.9 and 82.9 +/- 7.5% VO2max. BL was sustained at 25.0 +/- 5.0 to 50.6 +/- 7.7% VO2max and increased linearly at 67.8 +/- 6.9 and 82.9 +/- 7.5% VO2max. There was a significant negative correlation for each subject between the percentage of oxy-Hb/Mb and iEMG (r = -0.947 to -0.993), between the percentage of oxy-Hb/Mb and BL (r = -0.890 to -0.982), and between the percentage of oxy-Hb/Mb and VO2 (r = -0.929 to -0.994) These results indicated that oxygenated hemoglobin/myoglobin concentration measured with NIR reflected the muscle activity and the lactic acidosis.

We compared the effect of recovery condition and durations on performance and muscle oxygenation during short-duration intermittent sprint exercise. 8 subjects performed a graded test and ten 5-s maximal sprints with 25-, 50-, and 100-s passive recovery (PR) or active recovery (AR) on a cycle ergometer. Peak power and percent decrease in power were determined. Oxygen uptake and blood lactate were measured during the sprint exercise. Oxyhemoglobin (O2Hb) and deoxyhemoglobin were measured using near-infrared spectroscopy. Peak power values were higher for PR than AR for the 25-s (2-9 sprints) and 50-s (2-6, 9, or 10 sprints) but not for the 100-s durations. Percentage decrease in peak power was lower for PR than AR in the 25-s (8.5±2.5 vs. 11.5±3.6%, P=0.008, ES=0.66) and 50-s (2.7±1.4 vs. 6.2±3.5%, P=0.007, ES=0.67) but not 100-s durations (2.1±1.3 vs. 3.1±2.6%, P>0.05). O2Hb variations were significantly higher for PR than AR for the 25-s and 50-s durations. AR was associated with reduced sprint performance and lower muscular reoxygenation. Performance was not affected over longer recovery durations regardless of recovery condition.

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Hand-grip strength, elbow flexion strength, trunk extension strength and knee extension strength, and body composition (measured by densitometry) were measured in 59 male students (mean 19.2 years) in order to compare the muscle strength of obese men, in relation to fat storage rate (% fat), with those of non-obese men. Their % fat ranged from 6.2-35.6%. Correlations of body weight and lean body mass were found to be significant with each muscle strength. Our findings presented that obese men had lower muscle strengths for body weight and lean body mass than non-obese men do. This might be the result of two characteristics, inactivity and weak willpower, of obese men. Besides, the 20% fat of threshold of obesity for men proposed by Behnke and Wilmore was reasonable from the viewpoint of the muscle strength because of the differences between group D (18.8% fat) and group E (23.8% fat).

The purpose of this study was to examine the relationships between the physiological characteristics of synchronized swimmers and their performance scores. The subjects were 16 trained female synchronized swimmers with a mean age of 17.2 +/- 1.7 years (mean +/- SD). The examined variables were body dimensions (height, width, body mass, circumference of the body and segment length), body composition, isokinetic muscle strength of the elbow and knee during extension and flexion, abdominal muscle endurance, anaerobic power (leg extension power and peak blood lactate concentration), aerobic power (maximum oxygen uptake [VO2max], swimming velocity at the onset of blood lactate accumulation [OBLA-V]), and flexibility (standing trunk flexion, prone trunk extension and distance between the open legs). The performance scores had significant correlations (p < 0.05) with isokinetic muscle strength of the elbow extension and flexion, and the knee extension, abdominal muscle endurance, leg extension power, VO2max x wt(-1), OBLA-V and distance between the open legs. However, no significant correlations were found between the performance scores and anthropometric variables. This study showed that the performance scores of synchronized swimmers correlated significantly with the functional aspects, and that muscle strength, muscle endurance and aerobic capacity seem to be particularly important determinants.

This study examined the relationship between Olympic distance triathlon (swim over 1.5 km, cycle over 40.0 km, and run over 10.0 km) and economy during a simulated laboratory test triathlon. Seventeen male triathletes conducted both maximal exercise tests and simulated laboratory triathlon. The latter test consisted of swimming (S), cycling (C) and running (R) stages as a continuous task using a flume-pool, a cycle ergometer and a treadmill, respectively. The exercise intensity and duration were 60% of VO2max during swimming, cycling and running for 30, 75 and 45 min, respectively. The index of economy was determined by the % VO2max at the last min of each stage during a simulated laboratory test triathlon. Results indicated that Olympic distance triathlon (total time) was correlated to swimming-VO2max (r = -0.621, p < 0.001), cycling-VO2max (r = -0.873, p < 0.001), running-VO2max (r = -0.891, p < 0.001), S-Economy (r = 0.208, ns), C-Economy (r = 0.601, p < 0.001) and R-Economy (r = 0.769, p < 0.001). There were also significant correlations between swimming time and swimming-VO2max (r = -0.648, p < 0.01), between cycling time and cycling-VO2max (r = -0.819, p <0.001), between running time and running-VO2max (r = -0.726, p < 0.001), between swimming time and S-Economy (r = 0.550, p < 0.05), between cycling time and C-Economy (r = 0.613, p < 0.01), and between running time and R-Economy (r = 0.548, p < 0.05). These results demonstrated that the larger VO2max during maximal exercise tests and smaller increment of VO2 during a simulated laboratory test triathlon indicating good economy were good predictors to determine the Olympic distance triathlon.

Minimally dressed men and women between 20 and 72 years old rested for 2 hr in 28, 20, 15, and 10 degrees C room temperatures (Ta). Older women maintained core temperatures during all exposures, partially due to rapid increases in metabolism. Regardless of Ta, blood glucose levels were higher in older than younger women during the first hour of the exposures (p less than .05). Free fatty acid levels in older women were double those of others (p less than .001). Epinephrine levels were 25% higher in men than women (p less than .05). Cortisol levels were 30% higher in younger than older adults, regardless of sex (p less than .01). All measurements, and norepinephrine, were elevated in all groups during the 10 degrees C exposure. Rapid increases in metabolism in older women during cold exposure may have been facilitated by substrate availability. This advantage may have resulted from greater utilization of cortisol and epinephrine, increased catecholamine sensitivity, or hormonal changes consequent to menopause.