Comparison of V̇O2 for buoyancy and propulsion during swimming between male and female

体脂肪は人体の水中体重を小さくするから, 水泳には体脂肪の多いことが有利な条件となる可能性がある。本研究は水泳の際に浮くために使われるV̇O2と推進のために使われるV̇O2を測定し, 水中体重の大小が実際の水泳にどれほどの影響を与えているかという点について検討したものである。 男女各3名, 計6名の泳者に, 泳速が0.6, 0.8及び1.0m/secのクロール泳を行わせ, V̇O2を測定した。その際腰に錘をつけて水中体重を増加させ, あるいは滑車を介した錘で腰を引き上げるようにして水中体重を減少させ, 各水中体重において上記の測定を行った。V̇O2値を水中体重に対してプロットすることによって得られる回帰直線の勾配から浮くためのV̇O2を, またY切片から安静時V̇O2を差し引くことによって推進のためのV̇O2を求めた。 1 浮くために必要なV̇O2は泳速とは無関係であり, その平均値は男子の方(352±140ml/min)が女子のそれ(186±83ml/min)より有意に大であった。この差は水中体重に大きく依存していて, 単位水中体重当りに換算すると男女の値は接近した(男子: 117±46ml/min, 女子: 91±36ml/min)。 2 推進のために用いられるV̇O2は, 泳速の増加に伴って指数関数的に増大した。その増加率は男子よりも女子の方が大であったが, それは女子の水泳能力が男子のそれより劣ることに関連していると考えられる。 3 総V̇O2に対する推進のためのV̇O2の割合は, 男子よりも女子において大きく, この点女子の水中体重の小さいことは水泳において有利な条件になっている。男子の世界記録に対する女子のそれの比率は, 競泳の場合には競走の場合より大きいが, この差は女子の体脂肪の多いことが水泳では有利に作用していることに由来するものと考えられる。Body fat lessens underwater body weight and may offer an advantage for swimming performance. The present study was undertaken to measure separately V̇O2 for buoyancy and that for propulsion during swimming in the swimming flume and to elucidate the advantage of lower underwater body weight in female. Three male swimmers and three female swimmers participated as the subjects. V̇O2 was measured during free style swimming at a constant speed of 0.6, 0.8 and l.0m/sec.Underwater weight was increased stepwisely by loading an extra-weight around the subject's waist or decreased by suspending a weight which pulls the waist upward via a wire and pulleies. V̇O2 at a given speed depended proportionally on the underwater weight. V̇O2 for propu1sion was estimated by subtracting resting V̇O2 from the intercept on the ordinate, and V̇O2 for buoyancy was calculated from the slope. 1) V̇O2 for buoyancy was independent of swimming speed and the average value for female swimmers was much smaller than that for male swimmers (352±140m1/min for male, 186±83m1/min for female). This difference in V̇O2 for buoyancy depended largely on the difference in underwater weight as the calculated values of V̇O2 for buoyancy per kg of underwater weight revealed much smaller difference between sexes (117±46m1/min for male, 91±36m1/min for female). 2) V̇O2 for propulsion increased exponentially with increasing speed. The increasing rate was larger in female than in male. This is probably because of relative inferiority of swimming ability in the female group in this study. 3) The rate of propulsion V̇O2 to total V̇O2 during swimming was larger in female than in male. This represents the advantage of lower underwater weight in female for swimming. This result offers the probable explanation for the discrepancy which exists in male-female ratio of the world records between swimming and running

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Volume: 150Start Page: 402End Page: 41

Relationship between swimming performance and maximal oxygen debt, maximal oxygen uptake, and oxygen requirement

エネルギー代謝能力と水泳記録との関係に及ぼす水泳効率(e)の影響, 浮力の影響, および無酸素的代謝と有酸素的代謝の関与の影響について検討することを目的とした. 無酸素的および有酸素的代謝能力の指標として, 最大酸素負債量(O2debtmax)と最大酸素摂取量(V̇O2max)をそれぞれ回流水槽泳で測定した. 毎分酸素需要量(Ė)とeはO2debtmax, V̇O2maxおよび水泳記録から算出した. 被検者は性・年齢・水泳記録の異なるクロール泳者44名であった. 100mの水泳速度とO2debtmaxとの相関は全被検者群でr=0.551(p<0.01)であったものが, e1(100m水泳のe)≦3.33の群(n=14)ではr=0.739(p<0.01), 3.33<e1≦4.19の群(n=17)ではr=0.912(p<0.01), 4.19<e1の群(n=13)ではr=0.645(p<0.05)となった. 400mの水泳速度とV̇O2maxとの相関は全被検者群でr=0.554(p<0.01)であったものが, e4(400m水泳のe)≦5.24の群(n=14)ではr=0.730(p<0.01), 5.24<e4≦6.56の群(n=17)ではr=0.927(p<0.01), 6.56<e4の群(n=13)ではr=0.486となった. 以上のように, 水泳記録と代謝能力との相関はeの不均一な全被検者群よりeのほぼ均一な集団において高くなったことから, 両者の関係はeの要因によって顕著に影響されると結論した. 代謝能力は体重当りの値で示すよりも絶対値で示した場合に水泳記録との相関が高かった. これは, 水泳では浮力の作用により体重が支えられるために生じたと考えられた. 100mと400mの水泳記録は, O2debtmaxあるいはV̇O2maxに対するよりĖに対して, より高い相関を示した. したがって, 短距離泳における有酸素的代謝量の貢献を, また中・長距離泳における無酸素的代謝量の貢献を無視できないと考えられる.The purpose of this study was to discuss the effect of swimming efficiency (e), buoyancy, and participation of aerobic and anaerobic metabolism on the relationship between swimming performance and energy metabolic capacity. The maximal oxygen debt (O_2 debt_max) and maximal oxygen uptake (V̇o_2max) were measured after and during swimming in a swimming flume, as a parameter of anaerobic and aerobic capacity, respectively. Oxygen requirement (Ė) and swimming efficiency (e) were calculated from O_2 debt_max, V̇o_2max, and swimming record. The subjects consisted of 44 freestyle swimmers with different sex, age and swimming record. The correlation between O_2 debt_max and 100m swimming speed was r=0.551 (p<0.01) for the group) of whole subjects, while the coefficients for the three groups classified in terms of e_1 (e in 100m swimming) were r=0.739 (p<0.01) for the low e_1 group (N=14, e_1=3.33), r=0.912 (p<0.01) for the intermediate e_1 group (N=17, 3.33<e_1=4.19), and r=0.645 (p<0.05) for the high e_1 group (N=13,4.19<e_1). The correlation coefficient between V̇o_2max and 400m swimming speed was r=0.554 (p<0.01) for the whole group including all the subjects, while these coefficients for the sub-groups formed for e_4 (e in 400m swimming) were r=0.730 (p<0.01) for the low e_4 group (N=14, e_4≦5.24), r=0.927 (p<0.01) for the intermediate e_4 group (N=17, 5.24<e_4≦6.56) and r=0.486 for the high e_4 group (N=13, 6.56<e_4). Thus, correlations between swimming performance and metabolic capacity became higher for the group of subjects with homogeneous e than for the group of whole subjects with greater variability in their e. This result suggests that the relationship between swimming performance and metabolic capacity is markedly effected by the factor of e. Correlations between swimming performance and metabolic capacity were higher in absolute value than in relative value (/kg). This is probably because body weight is supported by buoyancy in swimming. Swimming performances in 100m and 400m races correlated higher with E than with O_2 debt_max or V̇o2_max. This suggests that contributions of aerobic metabolism in sprint race, and of anaerobic metabolism in middle and long distance races should not be underestimated