Morse C I, Wüst R C I, Jones D A, de Haan A, Degens H
Institute for Biophysical and Clinical Research into Human Movement (IRM), Manchester Metropolitan University, Cheshire, UK.
Acta Physiol (Oxf). 2007 Oct;191(2):123-9. doi: 10.1111/j.1748-1716.2007.01721.x. Epub 2007 Jun 5.
To determine whether muscle function is compromised in healthy smokers in comparison with activity-matched non-smokers.
Nine male smokers (aged 22.2 +/- 2.5 years: mean +/- SD) with a smoking history of 2.5 +/- 3.1 pack years, and ten male control participants (25.4 +/- 2.9 years) matched for physical activity level participated in this study. Knee extensor strength was measured using isometric maximal voluntary contractions. Voluntary activation of the quadriceps and co-activation of the biceps femoris were determined using interpolated twitches and surface electromyography respectively. The frequency-torque relationship and fatigue resistance were assessed with electrically evoked contractions. A fatigue index was determined as the ratio of final torque to initial torque during a series of isometric contractions (2 min; 30 Hz; 1 s contraction/1 s rest). Quadriceps anatomical cross sectional area was measured with MRI at 50% of femur length.
Maximal voluntary contraction torque, quadriceps anatomical cross sectional area, knee extensor torque/quadriceps cross sectional area, activation, co-activation and force-frequency relationship were similar, whereas the fatigue index was 17% lower in smokers than non-smokers.
In young men smoking does not significantly affect quadriceps muscle mass and contractile properties, but does reduce fatigue resistance of the quadriceps muscle, which was not attributable to differences in physical activity.
与活动量匹配的非吸烟者相比，确定健康吸烟者的肌肉功能是否受损。
九名男性吸烟者（年龄22.2±2.5岁：均值±标准差），吸烟史为2.5±3.1包年，以及十名身体活动水平匹配的男性对照参与者（25.4±2.9岁）参与了本研究。使用等长最大自主收缩测量膝关节伸肌力量。分别使用插入式抽搐和表面肌电图确定股四头肌的自主激活和股二头肌的共同激活。通过电诱发收缩评估频率-扭矩关系和抗疲劳能力。疲劳指数定义为一系列等长收缩（2分钟；30赫兹；1秒收缩/1秒休息）期间最终扭矩与初始扭矩的比值。在股骨长度的50%处用MRI测量股四头肌的解剖横截面积。
最大自主收缩扭矩、股四头肌解剖横截面积、膝关节伸肌扭矩/股四头肌横截面积、激活、共同激活和力-频率关系相似，而吸烟者的疲劳指数比非吸烟者低17%。
在年轻男性中，吸烟不会显著影响股四头肌的肌肉质量和收缩特性，但会降低股四头肌的抗疲劳能力，这与身体活动的差异无关。
