Morinder Gunilla, Mattsson Eva, Sollander Clara, Marcus Claude, Larsson Ulla Evers
Department of Neurobiology, National Childhood Obesity Centre, Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden.
Physiother Res Int. 2009 Jun;14(2):91-104. doi: 10.1002/pri.428.
The six-minute walk test (6MWT) is increasingly used in clinical practice. The aims of this study were to determine the reproducibility of the 6MWT in obese children and adolescents, to describe walking capacity in this population and compare the results with values from normal-weight children (known group validity), and, finally, to describe the correlation between distance walked and estimated maximum oxygen uptake (VO(2)max).
Reproducibility was determined by a test-retest design and known group validity by a comparative design. The 6MWT was first test-retested in 49 obese children (30 boys, 19 girls, 8-16 years, body mass index [BMI] 24.9-52.1 kg?m(-2)). Then, for validation, 250 obese children (126 boys, 124 girls, 8-16 years, BMI 23.2-57 kg/m(2)) and 97 normal-weight children (48 boys, 49 girls, 8-16 years, BMI 13.3-23.2 kg.m(-2)) performed the 6MWT. The obese children also performed a sub-maximal bicycle ergometry test.
In the test-retest, the obese children walked 571 m the first test and 57 m the second (p = 0.578). The measurement error (S(w)) was 24 m, coefficient of variation (CV): 4.3% and the intraclass correlation (ICC1:1): 0.84. Repeatability was 68 m, and limits of agreement were +71 and -65 m. In comparison mean (standard deviation), six-minute walk distance (6MWD) in the obese children was 571 m (65.5), and in the normal-weight children, 663 m (61.1) (p < 0.001). The correlation between 6MWD and estimated VO(2)max (r = 0.34) was low.
The 6MWT showed good reproducibility and known group validity, and can be recommended for use in clinical practice in the studied population. To evaluate individual outcomes after intervention, the 6MWD needs to change by >68 m to be statistically significant. The 6MWD performed by obese children averaged 86% of the distance normal-weight children walked. In obese children, the correlation between 6MWD and estimated VO(2)max was low, hence the 6MWT cannot substitute a bicycle ergometry test.
六分钟步行试验（6MWT）在临床实践中的应用日益广泛。本研究旨在确定6MWT在肥胖儿童和青少年中的可重复性，描述该人群的步行能力，并将结果与正常体重儿童的值进行比较（已知组效度），最后描述步行距离与估计的最大摄氧量（VO₂max）之间的相关性。
通过重测设计确定可重复性，通过比较设计确定已知组效度。首先对49名肥胖儿童（30名男孩，19名女孩，8 - 16岁，体重指数[BMI]24.9 - 52.1 kg·m⁻²）进行6MWT重测。然后，为进行效度验证，250名肥胖儿童（126名男孩，124名女孩，8 - 16岁，BMI 23.2 - 57 kg/m²）和97名正常体重儿童（48名男孩，49名女孩，8 - 16岁，BMI 13.3 - 23.2 kg·m⁻²）进行了6MWT。肥胖儿童还进行了次极量自行车测力计测试。
在重测中，肥胖儿童第一次测试步行571 m，第二次测试步行57 m（p = 0.578）。测量误差（S(w)）为24 m，变异系数（CV）：4.3%，组内相关系数（ICC1:1）：0.84。重复性为68 m，一致性界限为 +71和 -65 m。相比之下，肥胖儿童的六分钟步行距离（6MWD）平均（标准差）为571 m（65.5），正常体重儿童为663 m（61.1）（p < 0.001）。6MWD与估计的VO₂max之间的相关性（r = 0.34）较低。
6MWT显示出良好的可重复性和已知组效度，可推荐用于该研究人群的临床实践。为评估干预后的个体结果，6MWD需要改变>68 m才有统计学意义。肥胖儿童进行的6MWD平均为正常体重儿童步行距离的86%。在肥胖儿童中，6MWD与估计的VO₂max之间的相关性较低，因此6MWT不能替代自行车测力计测试。
