Beppu Mizobe Gakuen College

PURPOSE: High temperature and high humidity make heat radiation inefficient, it is easy to suffer from hyperthermia during exercise. This study examined the effect of cooling by the highly concentrated artificial carbonic acid water at rest following exercise. METHODS: Subjects were nine male students who consented to participate in the present study. Subjects were not permitted to consume alcohol on the day before the test, engage in exercise on the day of the test, or eat during the 2 hours prior to the start of the test. After 60 min resting state in a controlled environment (room temperature, 29°C; relative humidity, 70%), they exercised by cycle ergometer at 75%HRmax for 20 minutes. Then the subjects were cooled using each of the following methods: immersion of both arms in highly concentrated artificial carbonic acid water (33°C), and immersion of both arms in tap water (33°C). The skin (forearm) and core (sub-lingual) temperatures and thermal sensation in the forearm and body were measured. RESULTS: The sum of core temperatures decreases to the experiment end, assuming the time of immersion start as standard, and was larger with the carbonic acid water (13.0 ± 0.99°C) than with the tap water (12.6 ± 1.89°C). However, there was no significant difference between the immersion trial comparisons. The skin temperature decreases with the carbonic acid water (1.55 ± 0.09°C) were significantly smaller than that with the tap water (1.91 ± 0.10°C). And at the time of immersion, each of the between immersion trial comparisons was significantly different in thermal sensation for the forearm. The subjects felt warmer with the carbonic acid water (5.94 ± 0.21) than that with the tap water (4.45 ± 0.18). CONCLUSION: The carbonic acid water was larger in the sum of the variation of decline of core temperature. These data indicated that carbonic acid attenuated skin vasoconstriction and suppressed the drop in blood flow compared to water. As a result carbonic acid decreased core temperature efficiently. These results suggest that forearm bathing in highly concentrated artificial carbonic acid might afford cooling efficiency without placing athletes under the burden of cold water stimulation.

Recently, designs for competitive swimsuits have become diversified. The influences of new swimsuit design on drag, buoyancy and physiological responses were measured in the previous studies. However, few studies have evaluated the association between swimsuit and performance during maximal swimming. PURPOSE: To examine the swimming speed, blood lactate, heart rate, perceptual response and stroke technique during freestyle swimming wearing a traditional body suit and a newly designed swimsuit. METHODS: Six competitive female swimmers (age, 19.0±0.6 yr; height, 161.8±5.3 cm; body weight, 52.7±3.5 kg) swam a 200-m maximal freestyle trial in a 25-m indoor pool wearing a traditional body suit (BS) and a suit designed to cover the body from shoulder to ankle (LJ). Blood lactate concentration (BLa), heart rate (HR) and rating of perceived exertion (RPE) were measured after the trial. Stroke counts were determined to calculate the arm stroke index (ASI) during swimming trials. Each subject was informed of the aims, possible risks, and benefits of this investigation both verbally and in writing prior to their signing an informed consent document. RESULTS: Maximal swimming velocity between the BS (1.483 ± 0.006 m/s) and LJ (1.496 ± 0.011 m/s) trial demonstrated no significant difference, but the four swimmers swam faster in the LJ trial (mean time 1.1 sec; range from 0.6 to 3.3 sec) than the BS trial. BLa (BS: 11.32 ± 1.26 mmol/l vs. LJ: 12.95 ± 1.43 mmol/l), HR (BS: 190.2 ± 4.6 bpm vs. LJ: 190.4 ± 4.7 bpm), and RPE (BS: 19.0 ±0.3 vs. LJ: 18.8 ± 0.5) between the two suit conditions at the completion of the maximal trial were not significantly different. ASI (BS: 97.37 ± 3.97 vs. LJ: 97.90 ± 4.85) that was calculated by dividing the number of total strokes by the velocity was also not significantly different between the suits. CONCLUSIONS: These findings indicate that the new type of swimsuit during maximal freestyle swimming does not provide a physiological and technical advantage.