Juntendo Sports Clinic, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan.
J Cardiol. 2009 Oct;54(2):273-81. doi: 10.1016/j.jjcc.2009.05.016.
Previous studies have demonstrated that cardiac rehabilitation (CR) improves exercise tolerance and muscle strength in patients with myocardial infarction (MI) and in patients after cardiac surgery. However, the association between exercise tolerance and muscular strength following CR and the comparison of relationships among various disease categories has not been fully examined. The purpose of the present study was to assess the relationship between exercise tolerance and muscle strength following CR in patients after cardiac surgery and patients with MI.
One hundred and four patients who participated in CR for 6 months were enrolled [post-cardiac valve surgery (VALVE), n=28; post-coronary artery bypass grafting (CABG), n=42; post-acute MI, n=34]. The exercise tolerance, thigh/calf circumferences, and muscle strength were measured before and after CR. At the baseline, the thigh circumference was significantly smaller in the VALVE group than in the MI group. There were significant positive correlations between peak VO(2) and muscle torques of the lower muscles in all groups. After 6 months, peak VO(2) and muscle torque were significantly increased in all groups (p<0.001). A positive significant correlation between percent increases in peak VO(2) and muscular strength was observed in the VALVE group (r=0.51, p<0.01), but not in the other groups. In addition, the changes in peak VO(2) and calf circumference after CR were significantly higher in the VALVE group than in the MI group.
These data suggest that exercise intolerance in patients after heart valve surgery may in part depend on decreased muscular strength. Further studies are needed to assess whether the strategy of increasing muscular strength of lower limb by programmed resistance training could be effective for improving exercise intolerance in patients after heart valve surgery and symptomatic patients with heart failure.
既往研究表明心脏康复（CR）可改善心肌梗死（MI）和心脏手术后患者的运动耐量和肌肉力量。然而，CR 后运动耐量和肌肉力量之间的相关性以及不同疾病类别的关系尚未得到充分研究。本研究旨在评估心脏手术后患者和 MI 患者 CR 后运动耐量和肌肉力量之间的关系。
共纳入 104 例参加 CR 治疗 6 个月的患者[心脏瓣膜手术后（VALVE），n=28；冠状动脉旁路移植术后（CABG），n=42；急性 MI 后，n=34]。在 CR 前后测量运动耐量、大腿/小腿周径和肌肉力量。基线时，VALVE 组大腿周径明显小于 MI 组。所有组的峰值 VO₂与下肢肌肉扭矩之间均存在显著正相关。6 个月后，所有组的峰值 VO₂和肌肉扭矩均显著增加（p<0.001）。VALVE 组中，峰值 VO₂和肌肉力量的增加百分比之间存在显著正相关（r=0.51，p<0.01），但其他组无此相关性。此外，VALVE 组 CR 后峰值 VO₂和小腿周径的变化明显高于 MI 组。
这些数据表明，心脏瓣膜手术后患者的运动耐量可能部分取决于肌肉力量的下降。需要进一步研究评估通过有计划的阻力训练增加下肢肌肉力量的策略是否能有效改善心脏瓣膜手术后患者和有症状心力衰竭患者的运动耐量。
