The purpose of this study was to investigate the influence of the force tremor (FT) on mechanomyographic (MMG) signals recorded by a condenser microphone (MIC) and an accelerometer (ACC) during measurement of agonist and antagonist muscles in sustained isometric contractions. Surface electromyographic (EMG) signals and MMG signals by MIC (MMG-_MIC) and ACC (MMG-_ACC) were recorded simultaneously on biceps brachii (BB) and triceps brachii (TB). Following determination of the isometric maximum voluntary contraction (MVC), 10 male subjects were asked to perform sustained elbow flexion and extension contractions at 30% MVC until exhaustion. We analyzed the root mean square (RMS) for all signals and compared the sum of the power spectrum (SPA) for 3–6 Hz and 8–12 Hz and the ratio of the sum of SPA for 3–6 Hz and 8–12 Hz in SPA for 3–100 Hz (SPA-_FT/SPA-_{3–100 Hz}) between MMG-_MIC and MMG-_ACC. During all sustained muscle contractions, the RMS of EMG and MMG-_MIC was significantly (p<0.05) increased in antagonistic muscle pairs, while the increase was more noticeable for the agonist than for the antagonist. In addition, the antagonist had a significantly (p<0.05) smaller amplitude than the agonist muscle. The RMS of MMG-_ACC, however, showed no significant (p>0.05) difference in RMS amplitude and slope between agonist and antagonist muscles during flexion. In extension, the MMG-_ACC-RMS amplitude showed a tendency to be higher in the antagonist than in the agonist, while their slopes showed no significant (p>0.05) difference. The SPA for 3–6 Hz and 8–12 Hz in MMG-_MIC showed a tendency to be higher in the agonist than the antagonist, and the slopes of the agonist were significantly (p<0.05) higher than those of the antagonist in all contractions. In MMG-_ACC, SPA and slopes for 3–6 Hz and 8–12 Hz tended not to differ between agonist and antagonist. The SPA-_FT/SPA-_{3–100 Hz} in MMG-_ACC showed that the antagonist was higher than that of the agonist in all contractions. The MMG-_MIC, however, showed a tendency toward no difference between the agonist and antagonist. In the assessment of muscle activity during simultaneous measurement of the agonist and antagonist during sustained muscle contractions, the MMG signal detected by MIC appeared to be less affected by FT than by ACC due to the different inherent characteristics of the two transducers.

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It has been reported that oxygen uptake (VO₂) increases exponentially with levels of the pedal rate during cycling. The purpose of this study was therefore to test the hypothesis that the O₂ cost for internal power output (P_int) exerted in exercising muscle itself would be larger than for an external power output (P_ext) calculated from external load and pedal rate during cycling exercise under various conditions of P_int and P_ext in a large range of pedal rates. The O₂ cost (ΔVO₂/ Δpower output) was investigated in three experiments that featured different conditions on a cycle ergometer that were carried out at the same levels of total power output (P_tot; sum of P_int and P_ext) (Exp. 1), P_ext (Exp. 2) and load (Exp. 3). Each experiment consisted of three exercise tests with three levels of pedal rate (40 rpm for a lower pedal rate: LP; 70–80 rpm for a moderate pedal rate: MP; and 100–120 rpm for a higher pedal rate: HP) lasting for 2–3 min of unloaded cycling followed by 4–5 min of loaded cycling. Blood lactate accumulations (2.3–3.4 mmol l⁻¹) at the HP were significantly higher compared with the LP (0.6–0.9 mmol l⁻¹) and MP (0.9–1.0 mmol l⁻¹) except for the LP in Exp. 1. The VO₂ (360–432 ml min⁻¹ for LP, 479–644 ml min⁻¹ for MP, 960–1602 ml min⁻¹ for HP) during unloaded cycling in the three experiments increased exponentially with increasing pedal rates regardless of P_ext=0. Moreover, the slope of the VO₂-P_int (13.7 ml min⁻¹ W⁻¹) relation revealed a steeper inclination than that of the VO₂-P_ext (10.2 ml min⁻¹ W⁻¹) relation. We concluded that the O₂ cost for P_int was larger than for P_ext during the cycling exercises, indicating that the O₂ cost for P_tot could be affected by the ratio of P_int to P_tot due to the levels of pedal rate.

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The relationship between fat-free mass (FFM) and excess post-exercise oxygen consumption (EPOC) has not been well researched because of the relatively small number of subjects studied. This study investigated the effects of FFM on EPOC and EPOC/maximum oxygen consumption. 250 Japanese male athletes between 16 and 21 years old from Nagasaki prefecture had their EPOC measured up to 40 minutes after short-duration exhaustive exercise. The value was named as EPOC_{40 min}. The proportions of EPOC up to 1, 3, 6, 10, and 25 minutes to EPOC_{40 min} were calculated and named as P1, P3, P6, P10, and P25, respectively. Body size and composition, VO₂max and resting metabolic rate (RMR) were also measured. Mean EPOC_{40 min} was 9.04 L or 158 ml/kg FFM. EPOC_{40 min} was related to FFM (r=0.55, p<0.001) and VO₂max (r=0.37, p<0.001). The ratio of EPOC_{40 min} to VO₂max was related to FFM (r=0.28, p<0.001). P1, P3, P6, P10, and P25 were negatively related to EPOC_{40 min}/FFM, EPOC_{40 min}/VO₂max, and FFM. Athletes who had larger FFM had larger EPOC40_{40 min} and EPOC40_{40 min}/VO₂max, and smaller P1, P3, P10, and P25.

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We have previously reported that there may be a relationship between bowel habits including functional constipation (FC) and irritable bowel syndrome and sleep health. However, our previous studies were based on only subjective parameters by self-reported questionnaire. The aim of this study is to investigate the relationship between bowel habits such as FC and sleep health using objective parameters. Sleep health was assessed by actigraphy measurement and bowel habits by fecal flora analysis. The FC and control subjects, whose bowel habits were defined at Rome II, were recruited from evaluated respondents in our previous study directed at middle-aged Japanese women, ten FC and ten control subjects participating in this study. Wake after sleep onset (WASO) and WASO (%) (WASO/total sleep time multiplied by 100) in FC subjects was significantly longer and greater than those in control subjects, respectively. Average activity during sleep in FC subjects was significantly higher than that in control subjects. FC had no effect on total sleep time. Bifidobacterium is broadly accepted to be useful intestinal bacteria for human health and one of the indices showing that the intestinal environment is in a desirable condition. Bifidobacterium counts per gram of wet feces and proportion in total bacterial cell counts in FC subjects were significantly lower than those in control subjects. In conclusion, these results suggest that corresponding to low Bifidobacterium counts and proportion, sleep in FC subjects may be worse than that in control subjects. There may be a relationship between bowel habits and sleep health. Bowel habits such as FC might be a risk factor for sleep disorders.

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Objective: The aim of this study was to evaluate the effect of a cool environment on the peripheral skin blood flow and subjective thermal sensations of female office workers and female students.
Methods: The subjects were 26 female bank employees (mean age, 38 years) who worked in a cool environment and 10 female college students (mean age, 22 years). The peripheral skin blood flow was measured using a laser Doppler blood flow meter. In each bank employee, peripheral skin blood flow was measured at three time points during the workday in the medical treatment room at their workplace. In the college students, peripheral skin blood flow was measured every hour between 9:00 and 17:00 in a laboratory. In both the medical treatment room and the laboratory, the room temperature was controlled at 24–26°C with a relative humidity of 55±10%. The bank employees and students were each divided into those with hypersensitivity to cold (Group A) and those without hypersensitivity to cold (Group B).
Results: When the 10 college students were in the cool environment (24–26°C), their peripheral skin blood flow generally decreased over time. The rate of decrease of this blood flow was greater in Group A than in Group B.
In the female bank employees, the peripheral skin blood flow was the lowest at 12:00 (before lunch), was increased at 13:00 (after lunch), and then was decreased at 17:30. However, the degree of the increase from before lunch to after lunch in Group A was about half of that in Group B.
Conclusion: Among female office workers and students, a cool environment reduced the peripheral skin blood flow of individuals with hypersensitivity to cold to a greater degree than in those without hypersensitivity to cold.

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The purposes of this study were to examine the relationships between various force-time parameters and muscle oxygenation kinetics during maximal sustained isometric grip (SIG) and maximal repeated rhythmic grips (RRG) with different grip intervals (interval times: 5, 4, 3, and 2 s). Subjects were 10 healthy young males, aged 20–26 years (height 173.9±7.3 cm, body mass 71.5±11.2 kg). After measuring maximal grip force, each subject performed the SIG and RRG tests with a target frequency of 12, 15, 20, and 30 grips·min⁻¹ (interval times: 5, 4, 3, and 2 s, respectively) for 6 min. The decreasing time until 80% MVC showed significant and high correlations with final force values in RRGs with over 3 s intervals (r=0.866–0.941), but not in the SIG and RRG with a 2 s interval. The time at the lowest Oxy-Hb/Mb value showed a significant and high correlation with the time at the highest Deoxy-Hb/Mb value only in the SIG and RRG with a 2 s interval (r=0.825–0.916). Oxy-Hb/Mb decreases markedly and deoxy-Hb/Mb increases after the onset of SIG due to the obstruction of blood flow caused by the increase in intramuscular pressure. A similar physiological response to that of SIG occurs also in RRG with a 2 s interval, but RRGs with intervals over 3 s achieve more resumption of blood flow in the muscular relaxation phase. Hence, in spite of the same RRGs, it was determined that RRGs with intervals over 3 s differ significantly in a changing pattern of grip force and muscle oxygen kinetics from RRGs with a 2 s interval.

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