The purpose of the present study is to investigate how to supply energy before and during triathlon (one of the hard endurance events) from the viewpoint of physical fitness and health. Experimental subjects were nineteen healthy Japanese males, 25 to 57 years of age, who had completed the fourth Kaike Triathlon (3.0 km swimming, 103.6km bicycling and 42.195km running). Energy expenditure and energy intake before and during the triathlon were estimated by the method of Numajiri (1976) and the Japanese Ministry of Public Welfare (1984). 1) Mean values of the exercise intensity (RMR) were 7.45, 5.16, and 9.17 during swimming, bicycling and runing, respectively. Mean value of the exercise intensity for the overall triathlon competition was presumed 7.261±0.88 RMR (x±SD). 2) Mean values and standard deviations of energy expenditure were 956.7±105.5kcal, 1837.6±l78.8kcal and 3006.3±345.1 kcal during swimming, bicycling and running, respectively. That is, an energy expenditure during marathon was presumed 52% of the overall energy expenditure of the triathlon. 3) Mean values of energy expenditure per body weight were 93.05 kcal/kg, 92.97 kcal/kg and 91.16 kcal/kg in the upper (elite), the middle (good) and the lower (slow) group, respectively. There are no significant differences among these three groups. That is, mean value of energy expenditure during the Kaike Triathlon was presumed about 93 kcal/kg, having nothing to do with the order of the competition. 4) Mean values and standard deviations of energy intake were 360.3±222.4 kcal, 1127.6±438.1 kcal and 524.3±305.2kcal, at breakfast, after swimming, during bicycling and running, respectively. 5) Five of experimental subjects had lost more than 1000 kcal and another five had lost 500 kcal or so before start of marathon running already. Apparently half of the subjects showed negative energy balance.

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The decline of physiological functions due to aging would be promoted by shortness of physical exercise. In the present study, the authors tried to elucidate the effect of physiological effect of exercise prescription aiming at health promotion. Six healthy men of 30-47 years of age served as the subjects. The exercise imposed on them was 20 min running on a tread-mill of 3 degrees inclination, and the intensity of exercise was regulated at 2/3 V_o_2 max for each subject. Accordingly, the running speed ranged from 120 m/min to 150 m/min. The exercise was imposed on them once a day and for 5 days a week. The exercise as such have continued for more than 12.5 years, viz. 659 weeks. Due to the long term exercise habit as such, the subjects can now generally meet the energy requirement with lower level of physiologi-cal functions such as low heart rate and small lung ventilation at rest. But it was noted that there was no appreciable increase in V_o_2 max as an index of physical fitness. This fact seems to mean that the exercise habit of men in their middle and elderly age gives effect of producing excellent mechanism of physiological efficiency such as promotion of O₂ uptake and O₂ Supply to the tissues, augrnentation of utilizing blood lipid as energy source and moreover, increase of lactate oxidation to decrease of blood sugar consmption. On the other hand, it was suggested that the long term exercise habit of men in their middle and elderly age would sometimes result functional abnormality such as anemia or arythmia. These symptoms should be discriminated from pathological state, but the subjects would have some uncomfortable feeling. Therefore, the exercise habit such as that in the present study have some problems to be solved regarding physiological adaptation from the view-point of health promotion.

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The changes in energy metabolites and corresponding force curves were studied during muscle fatigue with respect to excitation frequency (20 and 50Hz) for contracting muscle in situ and by means of ³¹P nuclear magnetic resonance (NMR) technique in vitro. The rat hind limb muscle group was stimulated via the tibial nerve by 0.5ms duration square pulses at different frequencies for a period of three minutes. The force signals recorded during repeated experiments were fed through an A/D converter and averaged by the use of a desk-top computer. ³¹P-NMR spectra were recorded from gastrochemius and soleus muscle of resting and after stimulation. Results indicated that 1) Iarge and significant decreases in high energy phosphate compounds (e.g., creatine phosphate and adenosine triphosphate (ATP)) were observed during prolonged electric stimulation at 50Hz in both the gastrocnemius and soleus muscles, 2) during 20Hz stimulation, muscle fiber type dependent changes in energy metabolites were observed: i. e., the gastrocnemius manifested a significant decline in creatine phosphate and ATP contents (p<0.01) while the soleus hardly showed any such changes, and 3) these metabolite changes occurring during different frequency stimulations were well reflected upon the rate of force decline in such that the calculated time constant for force fatigue during 50Hz stimulation was significantly shorter than obtained during 20Hz stimulation (p<0.01). The observed difference in the force fatigue time constants could be, at least in part, explained by the difference in the rate of ATP hydrolysis (e.g., the energy cost for contraction, Ca⁺⁺ diffusion and uptake, ATP-linked sodium-potassium pump). It was suggested that force fatigue may ultimately be due to a failure of the rate of energy supply to meet demand, but the precise expression of this defect might vary, such that failure of membrane excitation and/or activation may predominate over failure of the energy supply.

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A flow injection system was designed to achieve enzymatic determination of blood lactate. The system is sensitive enough for use with human blood (0.2-2.0 mM). Deproteinized blood samples can be analyzed at 60 h^-1. The coefficient of variation is 1-2% for 4mM of blood lactate. The flow injection system can be sussessfully employed to monitor the level of blood lactate accumulated during exercise in man.

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