Reliability and validity of the six-minute arm test for the evaluation of cardiovascular fitness in people with spinal cord injury

Abstract

Objectives: To design a submaximal arm ergometry test (six-minute arm test [6-MAT]), for persons with spinal cord injury (SCI) and to determine the test-retest reliability and concurrent validity of this test.

Design: Prospective, exploratory, methodologic study. To determine test-retest reliability, subjects completed the 6-MAT on 2 days, separated by 1 week. Validity was determined by comparing 6-MAT results with peak oxygen consumption (VO2peak).

Setting: Tertiary rehabilitation center.

Participants: Thirty subjects with SCI (mean age, 36.3y; 83% male).

Interventions: Not applicable.

Main outcome measures: Subjects were evaluated on the 6-MAT and a VO2peak test.

Results: All subjects were able to complete the 6-MAT. Test-retest reliability of steady-state oxygen consumption (VO2) and heart rate during the 6-MAT were excellent (intraclass correlation coefficient [ICC], .81; 95% confidence interval [CI], .58-.92; ICC=.90; 95% CI, .75-.96, respectively). The correlation between VO2peak and 6-MAT VO2 was excellent (r=.92) and the correlations between VO2peak and 6-MAT heart rate (r=.63) and VO2peak and 6-MAT power output (r=.73) were good.

Conclusions: This study showed that the 6-MAT has acceptable values for test-retest reliability and validity. The 6-MAT should be further tested for responsiveness to enhance its use as a clinical tool.

Figures

Figure 1

Distribution of subject lesion levels

Figure 2

Figure 2a Scatter-plot comparing HR during 6-MAT test 1 and test 2; 2b Scatter-plot comparing VO2 during 6-MAT test 1 and test 2 (light circle, subjects with paraplegia; dark square, subjects with tetraplegia)

Figure 3

Figure 3a Bland Altman plot of difference in 6-MAT HR between time 1 and time 2 versus average HR from time 1 and time 2; 3b Bland Altman plot of difference in 6-MAT VO2 between time 1 and time 2 versus average VO2 from time 1 and time 2 (light circle, subjects with paraplegia; dark square, subjects with tetraplegia)

Figure 4

Scatter-plot comparing VO2 during the 6-MAT and VO2peak (r=0.92) (light circle, subjects with paraplegia; dark square, subjects with tetraplegia)