Validity and Utility of 6-minute-walk Test and WALK(Walking-Stair-Climbing) Test to Assess the Exercise Capacity in Hemodialysis Patients

Park, Sun Mee; Ahn, Seok Joo; Lee, Ji Eun; Kim, Yong Soo; Lee, Sang Haak; Moon, Hwa Sik; Chang, Yoon Sik; Bang, Byung Kee

Abstract

The survival rate in ESRD patients is increased in recent several years. Therefore the Quality of Life and rehabilitation became more important. To evaluate the validity and utility of the walk performance test such as the 6-minute-walk test and WALK test as a substitute of exercise ergometry, we examined the cycle ergometer-graded exercise test for physiologic exercise capacity(VO2max) and walk performance test in hemodialysis patients. The walk performance test was done 3 times of at least 48 hour interval before dialysis in randomly sampled 21 patients. The cycle ergometer-graded exercise test was done in interdialysis day. The result was as following : 1) The mean distance of 6 minute walk test was 472.6+/-105.2m(1st 448.9+/-111.6m, 2nd 479.1+/-89.8m, 3rd 489.9+/-113.4m) and Ratings of Perceived Exertion (RPE) overall 10.4+/-1.7(1st 10.3+/-2.1, 2nd 10.5+/-1.6, 3rd 10.5+/-1.6) and RPE leg 11.2+/-2.7(1st 11.0+/-2.8, 2 nd 11.1+/-2.5, 3rd 11.4+/-2.8). The difference between the test was not significant. 2) The mean time of walking-stair-climbing test was 62.9+/-5.0sec(1st 64.9+/-5.7sec, 2nd 61.9+/-5.7sec, 3rd 61.8+/-5.6sec) and RPE overall 10.7+/-1.9(1st 10.7+/-2.2, 2nd 10.9+/-2.3, 3rd 10.5+/-1.2) and RPE leg 10.9+/-2.7(1st 11.1+/-2.9, 2nd 10.9+/-2.6, 3rd 10.8+/-2.6). The difference between the test was not significant. 3) The VO2max was 13.8+/-5.3mL/kg/min and 46.5+/-14.8% of predicted value. 4) At the finish of the cycle ergometer-graded exercise test, the heart rate did not increase over 100 bpm in 13 patients. 5) The VO2max was significantly correlated with the age(r=-0.604, p<0.01), WALK test(r=-0.453, p<0.05), 6 minute walk test(r=0.561, p<0.05). In conclusion, the 6 minute walk test and WALK test are simple, reliable tests to assess the exercise capacity and predict VO2max in hemodialysis patients.