中等度の喫煙が体力や漸増運動時の局所筋の酸素動態におよぼす影響 Influence of Moderate Smoking on Physical Fitness and Local Muscle Oxygenation Profile during Incremental Exercise

6名の喫煙者と10名の非喫煙者を対象として,漸増運動が体力や末梢循環(酸素動態)におよぼす影響について調べた.酸素動態の計測には近赤外線分光装置を用いて右外側広筋の酸素化ヘモグロビン濃度(0_2Hb)の変化量を測定した.その結果80%HR_<max>到達時や血中乳酸濃度2mmol/l時の仕事量,VO_2やHRには2群間で有意差はなかったが,運動強度によってはRRや酸素当量が喫煙者において著明に高い傾向がみられた.0_2Hbは喫煙者の内5名では運動の強度が上がるにつれて減少し続ける傾向がみられたが,非喫煙者では8名で運動中を通じて増加し続けた.喫煙者では中等度の運動強度でも筋の酸素需要に供給が追いついていない可能性がある.喫煙者が運動を行う際には中等度の強度であっても末梢循環動態に十分な配慮が必要であることが示唆された.

To reveal the influence of chronic moderate smoking on physical fitness and local muscle oxygenation profile, we compared the oxygen uptake (VO_2), CO_2 output, respiratory rate, minute ventilation and blood lactate accumulation between six moderate smokers and ten non-smokers during incremental exercise. In order to know the difference of the peripheral oxygen supply to the muscles between the two groups, oxygenation profiles based on the changes of oxygenated hemoglobin (0_2Hb) in the right vastus lateralis muscles were observed using near-infrared spectroscopy (NIRS). The intensity of incremental exercise using a bicycle ergometer was from 10 W to 80% of the maximum heart rate (80%HR_<max>) of each subject. There were no significant differences between the two groups in VO_2 and work rate at the level of 2 mmol/l lactate or 80%HR_<max>(P<0.05). However, as to the local muscle oxygenation profile during exercise, 5 out of the 6 smokers showed a decrease of O_2Hb throughout the incremental exercise, but 8 out of the 10 non-smokers showed a gradual increase of O_2Hb throughout the exercise. In conclusion, our results suggest that chronic moderate smoking might cause a change of local muscle oxygenation profile during incremental exercise, even if the smokers have shown no decrease in physical fitness.