Abstract: Background　Obese patients undergoing bariatric surgery generally have preoperative problems associated with reduced exercise capacity，which affects their postoperative weight loss outcomes.6MWT is an easy and well-validated method for evaluating the functional abilities of obese adults.Studies have shown that there is a close relationship between exercise capacity and different body composition indicators.However，there is no research conducted to investigate the impact of body composition on exercise capacity in these patients before the bariatric surgery.Objective　To investigate the impact of body composition on 6MWD in bariatric surgery candidates.Methods　Convenience sampling was used to recruit 202 obese patients undergoing metabolic surgery in bariatric and metabolic surgery of a grade A tertiary hospital in Jiangsu Province from August 2017 to November 2018.All included subjects measured body composition with InBody 770 Body Composition Analyzer，and then performed 6MWT before surgery.Pearson correlation analysis was performed to explore the correlation between 6MWD and body composition.Stepwise multiple regression was used to examine the association between preoperative body composition and 6MWD.Results　The mean preoperative distance of 6MWD was（486.65±52.26） m in patients before metabolic surgery，and（520.13±60.56） m in healthy adults of the same age，height and body mass，with statistically significant difference（t=-23.718，P<0.001）.Analysis results showed that 6MWD was negatively correlated with weight（r=-0.236，P<0.05），body fat mass percentage（FM%）（r=-0.357，P<0.05），FM% of upper limps （r=-0.363，P<0.05），of lower limbs（r=-0.344，P<0.05），and of trunk（r=-0.240，P<0.05），and BMI（r=-0.358，P<0.05） and visceral fat area（r=-0.258，P<0.05），while there was a positive relationship between 6MWD and body's fat-free mass percentage（FFM%）（r=0.357，P<0.05），FFM % of upper limps（r=0.363，P<0.05），of lower limbs（r=0.344，P<0.05），and of trunk （r=0.240，P<0.05）．Stepwise multiple regression showed that BMI and FFM% of lower limbs were independently associated with 6MWD（P<0.05）.Conclusion　Patients awaiting bariatric surgery are found with reduced exercise capacity.The lower the BMI and the higher the FFM% of the lower extremity，the farther the patient's 6MWD is.

Key words: Bariatrics, Bariatric medicine, 6 min walk test, Body composition

摘要： 背景　行代谢手术的肥胖患者术前普遍存在运动能力降低的问题，影响其术后减重效果。6 min步行试验（6MWT）可用于评估肥胖患者的运动能力。研究表明运动能力与身体成分不同指标之间关系密切，但目前尚缺乏针对代谢术前肥胖患者身体成分对运动能力影响的相关研究。目的　探讨身体成分对代谢术前肥胖患者6MWT行走距离的影响。方法　采用方便抽样法，选取2017年8月—2018年11月在江苏省某三级甲等医院减重代谢外科行代谢手术的202例肥胖患者为研究对象。应用Inboby770人体成分分析仪对所有患者进行身体成分测定，测定结束后行6MWT，记录6 min步行距离（6MWD）。6MWD与身体成分的相关性分析采用Pearson相关分析，采用多元逐步线性回归分析代谢术前患者6MWD与身体成分的关系。结果　代谢术前患者6MWD平均为（486.65±52.26） m，相同年龄、身高、体质量健康成人预测平均距离为（520.13±60.56） m，两者6MWD比较，差异有统计学意义（t=-23.718，P<0.001）。相关分析结果显示，6MWD与体质量（r=-0.236，P<0.05）、全身体脂率（FM%，r=-0.357，P<0.05）、节段FM%（上肢：r=-0.363，P<0.05；下肢：r=-0.344，P<0.05；躯干：r=-0.240，P<0.05）、体质指数（BMI，r=-0.358，P<0.05）及内脏脂肪面积（VFA，r=-0.258，P<0.05）呈线性负相关；与去脂体质量百分比（FFM%，r=0.357，P<0.05）和节段FFM%（上肢：r=0.363，P<0.05；下肢：r=0.344，P<0.05；躯干：r=0.240，P<0.05）呈线性正相关。多元逐步线性回归分析结果显示，BMI和下肢FFM%是患者6MWD的影响因素（P<0.05）。结论　代谢术前肥胖患者运动能力较健康人群降低，BMI值越低、下肢FFM%越高，患者6MWD越远。

关键词: 肥胖病学, 肥胖医学, 6 min步行试验, 身体成分