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 ³¹P magnetic resonance spectroscopy (³¹P-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 (H₂PO₄-) 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 H₂PO₄- 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 H₂PO₄- 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.

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.

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) .
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.
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.

Background: Understanding the long-term effects of environment on health behavior is important for the promotion of population-based physical activity.Purpose: The purpose of this study was to examine the relationship between perceived environment and active commuting among Japanese adults.Methods: Internet-based cross-sectional survey were conducted to 3,000 Japanese adults aged 30-59 years. Seven sociodemographic attributes (gender, age, marital status, employment status, living status, educational attainment and household income), type of commute and International Physical Activity Questionnaire Environment Module were assessed by self-administered questionnaire.Results: Of all respondents to the survey, 2,032 (mean age: 43.8±9.2, male: 62.5%) were employed. Those who use an active commute were 1,401 (68.9%). In both genders, high residential density (male: OR=2.28, female: OR=3.08), good access to shops (OR=2.03, 3.06), public transportation (OR=1.65, 3.78), recreational facilities (OR=1.31, 1.44), presence of sidewalks (OR=1.42, 1.77), crossroads (OR=1.87, 1.76), having a destination (OR=1.84, 2.34), and not having household vehicles (OR=15.13, 41.24) were associated with an active commute. The results indicated some gender differences. Among male, the presence of a bicycle lane and good aesthetics was positively associated with the active commute, while traffic safety was negatively associated. On the other hand, crime safety was associated with the active commute in female.Conclusion: The results indicate that perceived environment was associated with the active commute among Japanese adults.

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 :
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.
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.
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.

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, VO₂, VCO₂) 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%VO₂max, 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%VO₂max (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.

Background: Epidemiological findings suggest that weight fluctuations are associated with unfavorable health outcomes compared with stable weight. However, the interrelationship between the weight cycling history and dieting status in a non-clinical male trial on the risk for bio-behavioral health is unclear. Objective: The purpose of this study was to examine the relation between weight cycling history as a result of intentional weight loss and bio-behavioral health in Japanese adult males. Method: A cross-sectional study was performed on a group of 146 Japanese working males (47.5±9.3 yr.). Each subject completed a series of self-reported questionnaires in which information about weight cycling history, current dieting practices, life-styles, and social background were assessed. Results of the physical check up were used to assess biological parameters. Self-reported weight cycling was defined as intentionally losing 10% of one's weight and regaining the lost weight. Results: Cyclers reported a significantly greater incidence of current dieting and recent weight gain compared with non-cyclers. Taking regular meals, eating breakfast everyday, and not eating snacks between meals every day were significantly less frequent among cyclers compared with non-cyclers after controlling for BMI. The adjusted odds ratio for AST abnormality was 5.46 (95%CI: 1.08 −27.67), ALT abnormality was 3.31 (95%CI: 1.24−8.78), and γ-GTP was 3.38 (95%CI: 1.07−10.67) among cyclers, compared with non-cyclers. Conclusion: These findings suggest that a history of weight cycling in men, regardless of current weight status, is associated with adverse bio-behavioral health. The risk for several liver enzyme abnormalities associated with weight cycling history was substantial, independent of relative body weight and lifestyle factors.
Weight ; Health ; brief historical notes, excludes case histories ; Japanese language ; Cephalic index

We aimed to elucidate the impact of the conducting state in exercise programs and the degree of improvement in sit-to-stand power index (STS-PI) on the continuation of Chokin exercise by participants one year from the completion of the intervention period. Subjects participated in a 12-week Chokin exercise class for the elderly, which consisted of 10 body mass-based exercises. As variables indicating exercise conditions, the number of exercise days weekly and the total number of sets performed during the intervention period were adopted. STS-PI was calculated using the time required to perform 10-times-repeated sit-to-stand task, and its relative change (%∆STS-PI) was used to represent the degree of improvement in physical function. Among 52 men and 129 women who responded to the inquiry about the continuation of Chokin exercise one year from the completion of the intervention period, 32 men and 93 women confirmed continuation of the exercise program. Logistic regression analysis showed that %∆STS-PI for men, as well as %∆STS-PI and the number of exercise days weekly for women, were factors associated with the decision of subjects to continue the Chokin exercise. These results indicate that the degree of improvement in STS-PI associated with the Chokin exercise class is a factor for continuing the exercise program one year from the completion of the intervention period, at least in elderly men and women. Furthermore, high exercise frequency during the intervention period may be associated with the decision to continue Chokin exercise after the completion of the intervention among women.

Previous studies showed associations of sedentary behavior with cardiovascular risks, independent of moderate-to-vigorous physical activity. However, few studies have focused on Japanese workers. This study examined the joint association of television viewing time (TV) and walking time (WT) with overweight/obesity among Japanese municipal office workers. A cross-sectional survey collected height, weight, and time spent in TV and WT from 2,175 Japanese workers, aged 22-62 years-old, by self-administered questionnaire. Participants were classified into four categories according to TV (dichotomized into long (>2 hours/day) and short (≤2 hours/day) by the median) and WT (dichotomized into long (≥30 minutes/day) and short (<30 minutes/day) by 30 minutes/day). Odds ratios (OR) for overweight/obesity (body mass index ≥25kg/m²) were calculated according to the four TV/WT categories, adjusted for potential confounders. Overweight/obesity accounted for 30.5% of men and 15.3% of women. Among men, the adjusted ORs (95% CI) of overweight/obesity were 1.14 (0.76, 1.70) for long TV/long WT, 1.13 (0.77, 1.65) for short TV/short WT, and 0.97 (0.67, 1.42) for short TV/long WT, compared with the reference category (long TV/short WT). Among women, the adjusted ORs (95% CI) were 0.70 (0.39, 1.13) for long TV/long WT, 0.55 (0.33, 0.94) for short TV/short WT, and 0.54 (0.33, 0.89) for short TV/long WT. Spending a long time watching television was associated with a higher risk of being obese in Japanese female municipal office workers, independent of WT. Further studies using prospective designs are warranted to develop an effective weight control program for Japanese workers.