Influence of transcutaneous electrical nerve stimulation on the distance walked by older adults during the 6-min test of walking endurance

The purpose of our study was to compare the influence of two types of transcutaneous electrical nerve stimulation (TENS) on the performance of older adults on the 6-min test of walking endurance and on the ability to maintain balance during upright standing. Twenty-six healthy older adults (72 +/- 5.4 yrs) performed tests of motor function while TENS was applied to the tibialis anterior and rectus femoris muscles of each leg. Linear mixed models were used to compare the influence of TENS on walking distance in a 6-min test of walking endurance and on sway-area rate in tests of standing balance. There was a significant decrease in the distances walked in each minute of the 6-min walk test for both the Continuous and Burst TENS modes compared with Baseline (p < 0.01 and p < 0.001, respectively). The influence of TENS on walking distance was associated with several significant effects on the mean and coefficient of variation for stride length and stride frequency between the first and last minute of the test and between the two TENS modes and the Baseline values. In contrast, there was no significant effect of TENS on sway-area rate in any balance test, which indicates that the supplementary sensory feedback compromised walking performance of older adults but not the ability to maintain balance during upright standing.