CHANGE OF FOREARM MUSCLE OXYGEN CONSUMPTION IN PEDIATRIE KIDNEY TRANSPLANT PATIENTS / 体力科学

The aim of the present study is to clarify the improvement of peripheral muscle oxygen consumption after successful renal transplantation. We investigated change of forearm (brachioradial muscle) muscular oxygen consumption in chronic renal failure children before and after renal transplantation. by using near-infrared spectroscopy.Oxygen consumption of brachioradial muscle was increased significantly after succesful renal transplantation. And half recovery time of brachioradial muscle oxygenation in arterial occlusion and exercise were decreased after renal transplantation.These results suggest that increased muscular blood flow and increased oxidative generation of ATP might contribute to the increased oxygen turn over after renal transplantation.

EFFECTS OF PHYSICAL ACTIVITY ON AGE-RELATED DECLINE IN OXYGEN DELIVERY TO WORKING MUSCLES / 体力科学

The purpose of this study was to determine the age and habitual physical activity on re-oxygenation time in working muscles following maximal cycling exercise (CycEXmax). Twelve sedentary middle-aged (50±6), 13 sedentary elderly (66±3), 13 active middle-aged (53±5), and 20 active elderly (67±5) were evaluated the half re-oxygenation time (T1/2 reoxy) as an index of oxygen delivery, using near-infrared spectroscopy at the vastus lateralis (VL) and lateral head of the gastrocnemius (LG) after CycEXmax. T1/2 reoxys at VL and LG were significantly greater in the elderly subjects than in the middle-aged subjects in both sedentary and active groups. T1/2 reoxys at VL and LG of the active group were smaller than those of the sedentary group, regardless of age. The results of this study suggest that habitual physical activity may attenuate age-related prolongation in T1/2 reoxy in working muscles although ageing delay T1/2 reoxy in working muscles.

MUSCLE OXYGENATION HETEROGENEITY IN A SINGLE MUSCLE AT REST AND DURING BICYCLE EXERCISE / 体力科学

We evaluated regional differences of muscle O₂ dynamics between distal and proximal sites in the vastus lateralis (VL) muscle using near infrared spatial resolved spectroscopy (NIR_SRS). forty-one male subjects performed a 30 W ramp incremental bicycle exercise test until exhaustion. The NIR_SRS probes were attached on each distal and proximal site in the VL. The pulmonary O₂ uptake and heart rate were monitored continuously during the experiment. The TOI at rest was significantly higher in proximal than distal sites (65.0±5.2 vs. 69.7±4.6%, p<0.001). The TOI at exhaustion was also significantly higher in proximal than distal sites (39.5±6.7 vs. 47.5±7.6%, p<0.001). Moreover, a significant correlation was found between VO₂max and the TOI at exhaustion in each proximal and distal site in the VL. Half time reoxygenation, the time to reach a value of half-maximal recovery, was significantly slower in distal sites than proximal sites (27.1±5.6 vs. 25.0±6.1 sec, p<0.01). In conclusion, lower muscle oxygenation at exhaustion in higher VO₂max may be due to enhanced O₂ extraction in high oxidative capacity muscle. In addition, slower reoxygenation and lower muscle deoxygenation at the distal site in the VL may be explained by differences in O₂ supply and/or muscle fiber composition between distal and proximal sites.

EFFECTS OF BICYCLE ERGOMETER EXERCISE AND PGE₁ INJECTION FOR PATIENTS WITH INTERMITTENT CLAUDICATION / 体力科学

The purpose of this study was to clarify the effects of bicycle ergometer training and prostaglandin E₁ (PGE₁) for patients with intermittent claudication. Subjects were divided into four groups : the medication group (M), the PGE₁ group (P), the exercise group (E) and the PGE₁ and exercise group (PE). The P group was injected with 10<i>μ</i>g of PGE₁, the E group performed bicycle ergometer exercise 3 times a week for 6 weeks, and the PE group was injected with PGE₁ and performed exercises. The maximal walking distance (MWD) was evaluated by a treadmill test. Muscle oxygenation level was measured by near-infrared spectroscopy and recovery half time (T_1/2) was calculated. MWD was significantly improved for P (142%), E (216%) and PE (240%) groups. T_1/2 was significantly improved in the E and PE groups. This study indicates that improvement of MWD was a result of development of muscle perfusion in lower limbs and PGE₁ injection may support exercise therapy.

Pattern of deoxygenation in vastus lateralis and rectus femoris muscles during a ramp-loaded cycling / 体力科学

The purpose of this study was to compare changes in oxygenation in the Vastus Lateralis (VL) and Rectus Femoris (RF) muscles during a ramp-loaded bicycle exercise. Twelve healthy males participated in the experiment. The test consisted of a leg arterial occlusion at rest and a ramp-loaded exercise (20 watts/min) using a bicycle ergometer until exhaustion. The changes in deoxygenation in each muscle was measured by near infrared spectrometer (NIRS) . The probes of NIRS were placed on VL and RF approximately 12 cm above the right knee. Oxy-Hb/Mb signals from NIRS were calculated as 100% at rest, with 0 % being the lowest value during the leg arterial occlusion. Pulmonary gas exchanges (VE, VO<SUB>2</SUB>, VCO<SUB>2</SUB>) were measured with an expiratory gas analyzer. In 10 subjects, muscle oxygenation level in VL decreased linearly until the deoxygenation limiting point (DOLP) -the point in exercise at which the deoxygenation rate decreases noticeably. However, in 2 subjects, the DOLP was not detected, and the muscle oxygenation level decreased linearly until exhaustion. The muscle oxygenation level in RF also decreased linearly until 70%VO<SUB>2</SUB>max, although the deoxygenation rate was smaller than that in VL. Thereafter, the muscle oxygenation level in RF continued to decrease until exhaustion. No DOLP was found in any subjects in RF. Compared with the muscle oxygenation level in RF at any points during the exercise, those in VL were lower until 90%VO<SUB>2</SUB>max (P<0.001) . However, the difference in muscle oxygenation levels between VL and RF at exhaustion was not noted. This study indicated that the patterns of deoxygenation in VL and RF during a ramploaded bicycle exercise were different.

The Relationship between Physical Fitness and Coronary Risk Factor Profiles in Japanese Women

The purpose of this study was to investigate the relationship between physical fitness and coronary risk factor profiles in Japanese women. The subjects were 1, 483 women (ages 30 to 69) who participated in a practical health promotion program. After medical examination, physical fitness was evaluated by conducting a symptom limited maximal exercise test by ergometer to measure maximum oxygen uptake (peakVO2) with an expired gas analyzer. The subjects were classified into 3 groups (high fitness, moderate fitness, and low fitness) according to age and physical fitness level. The results showed that the subjects in higher fitness groups had lower levels in: body mass index (BMI), percentage of body fat, waist−hip ratio, resting blood pressure, and atherogenic index, and higher HDL−cholesterol compared to those in lower fitness group. Even after adjustment for the effects of age and BMI, the subjects in the higher fitness groups had better coronary risk factor profiles. These results suggest that among Japanese women a high level of physical fitness is related to favorable coronary risk factor profiles.

Eating disorder symptoms, weight loss behaviors and weight-cycling in female college students: Correlates of exercise practice / 体力科学

We examined the relationships between exercise, eating disorders, weight loss-related concerns/behaviors and weight-cycling (weight loss and regain ≥10%) . The subjects were comprised of 1123 female college students (aged 18.9 ± 1.1 yrs.) who each completed a questionnaire on eating attitudes [Eating Attitude Test (EAT) ], dieting behavior [Dieting Behavior Scale (DBS) ], purging behavior (self-induced vomiting and use of laxatives) and previous weight-cycling. Subjects were divided into four groups on the basis of their current regular exercise behavior as follows non-exercisers (Ns) (N=704), low-intensity, low-frequency exercisers (LLs) (N=106), moderate/high-intensity, low-frequency exercisers (MLs) (N=184) and moderate/high-intensity, high-frequency exercisers (MHs) (N=129) .<BR>Analyses of variances showed significant differences among the four groups for weight and eating concerns, and weight loss behavior. Not only MHs, but also MLs exhibited higher Dieting subscale score ratings on the EAT than Ns. MHs and MLs also showed higher Structured- and Extraordinary-Diet subscale score ratings on the DBS than Ns and LLs. Significantly more MHs used self-induced vomiting than the other three groups, whereas significantly more MHs and MLs used laxatives than Ns. MHs who had experienced weight-cycling were by far more likely to have unhealthy weight loss behaviors and eating disorders than Ns.<BR>These findings suggest that vigorous exercise in female college students is associated with eating disorder- and weight loss-related concerns/behavior even though the students do not exhibit frequent exercise habits. Though regular exercise is desirable, careful attention must be paid to behavioral factors related to eating and weight loss in exercising female college students.

Implications of the amino acid metabolism regarding changes in the mood profile following ultra-endurance exercise / 体力科学

To elucidate the phenomenon of central fatigue, we investigated the changes in the plasma amino acid level and false neurotransmitter (FNT) level during ultra-endurance exercise. Twenty-one male Japanese participants of the 1993 Ironman Japan Contest, held at Lake Biwa, were examined. Blood sampling and a questionnaire on the Profile of Mood States (POMS) test were collected two days before, immediately after and one-day following the race. The POMS questionnaire showed various changes especially due to fatigue. Indeed, the fatigue score significantly increased after the race. Although the confusion score significantly increased after the race, it quickly recovered to the pre race level the following day. The plasma concentration of the branched-chain amino acids (BCAA) decreased after the race, while the level of aromatic amino acids (AAA) increased, thus resulting in a significant decrease in the BCAA/AAA ratio. The plasma level of octopamine, one type of FNT, significantly increased after the race (p<0.01) . The blood ammonia level increased after the race, but recovered to the pre-race level one-day after the race. Although no change was observed in the total tryptophan (Trp) level, the level of free Trp significantly increased during the race. The significant increases in the plasma 5-hydroxyindoleacetic acid (5HIAA), homovanillic acid (HVA) and HVA/dihydroxyphenylacetic acid (DOPAC) ratios thus suggest the serotonin (5 HT) and dopamine (DA) neuron systems activated after the race. In conclusion, ultra-endurance exercise caused a disorder of both the amino acid and monoamine metabolisms. Furthermore these changes were also related with mood changes, especially fatigue, i. e. central fatigue. These results suggest that the measurement of both the plasma BCAA/AAA ratio and FNT may therefore be useful in quantifying exercise induced central fatigue.

The relationship between endurance time and fatigue factors at varying intensities in handgrip isometric exercise / 体力科学

The purpose of the present study was to investigate the relationship between endurance time and fatigue factors at varying intensities of handgrip isometric exercise. Seven subjects performed isometric contractions at 10%, 30% and 50% of maximum voluntary contraction (MVC) sustained to exhaustion. Continuous changes in high-energy phosphates and muscle oxygen content (oxy-Hb/Mb) in the forearm flexor muscle were measured by <SUP>31</SUP>P magnetic resonance spectroscopy (<SUP>31</SUP>P-MRS) and near infrared spectroscopy (NIRS), respectively. The endurance time to exhaustion was 963±236 (mean±S. D.), 209±41.9 and 95.3±13.6s at 10%, 30% and 50%MVC, respectively, From the onset of exercise at each %MVC, both PCr and oxy-Hb/Mb fell and Pi (H<SUB>2</SUB>PO<SUB>4</SUB>-) rose linearly with time, whereas intracellular pH remained relatively constant at resting values during the early phase. Thereafter, intracellular pH showed a linear decline. The rates of pH decline were 0.03±0.02, 0.22±0.14 and 0.51±0.17 pHunit/min, while the rates of H<SUB>2</SUB>PO<SUB>4</SUB>- increase were 20.9±19.3, 118±48.9 and 434±242 (% of resting) /min at 10%, 30% and 50%MVC, respectively. There were correlations between the changes in endurance times to exhaustion and the rates of pH decline (r= -0.58--0.87) and H<SUB>2</SUB>PO<SUB>4</SUB>- increase (r=-0.37--0.74, (n=7) ) at each intensity of exercise. In particular, significant correlations (p<0.05) between endurance time and the rate of pH decline were found at both 10% and 30%MVC. These results suggest that muscle fatigue (endurance time) at each intensity in handgrip isometric exercise is closely correlated with the rate of pH decline.

Effects of local cooling and heating in the triceps surae muscles during sustained isometric contraction / 体力科学

A study was conducted to examine activity patterns of surface electromyograms (EMGs) in the triceps surae muscles (medial gastrocnemius, MG ; lateral gastrocnemius, LG ; soleus, SOL) during isometric contraction in plantar flexion (60% MVC, 20% MVC) after immersion in water at three different temperatures. Seven healthy male subjects were immersed in water at 2-3°C (ICE), 19-21°C (MID), and 40-42°C (HOT) . The results of the study are summarized as follows :<BR>1) In the MG and LG, there was a slight increase in the rate of integrated electromyograms (IEMGs) in the MG (the main agonist muscle) . However, the rate of increase in the LG, which is the synergistic muscle, was much greater than that in the MG when contraction was sustained at 60% MVC. Therefore, the activity pattern suggests that muscle activity in the LG compensates for that in the MG.<BR>2) The IEMGs of the SQL with sustained contraction, increased significantly after immersion in HOT and MID, but the IEMGs decreased after immersion in ICE. These results suggest that the recruitment threshold in slow-type motor units should increase during sustained isometric contrac-tion in ICE.<BR>As illustrated above, the activity of the LG increased to compensate for that of MG. In the SQL, muscle activity with sustained contraction decreased in ICE. These results suggest that control mechanisms of the central nervous system might play an important role in the associated movement of the triceps surae muscles.

Nutritional intakes in ultraendurance exercise (triathlon) before and during competition / 体力科学

Daily activities and food consumption, for the 2 days before and the day of competition, were investigated in 18 Japanese male triathletes participating in the Ironman Japan Competition at Lake-Biwa in 1991. Energy intakes and the energy intake to expenditure ratio, one and two days before and on race day, were 4005±895 kcal and 151±40%, 5000±1356 kcal and 203±53% and 5170±1799 kcal and 55±27%, respectively. Carbohydrates constituted 62, 4±11.6%, 61.3±7.7% and 76.7±5.6%, respectively, of these meals. Mean vitamin and mineral intakes were highly variable. Total water intake at breakfast and during the events was 7488±3653 ml. Salt intake appeared to be inadequate. Some triathlestes, who consumed only meals (no supplements) or had not stored adequate nutrients prior to the competition, had transiently subnormal nutrient levels during these extremely demanding events.