“Should I stay or should I go now?” Recovery time effect on walking capacity in symptomatic peripheral artery disease.

Summary OBJECTIVE: To investigate the effect of recovery time on walking capacity (WC) throughout repeated maximal walking bouts in symptomatic lower extremity peripheral artery disease (PAD). METHODS: The effect of recovery time on WC (maximal walking time) was determined in 21 PAD participants in three experimental conditions (recovery time from 0.5-9.5 min + a self-selected recovery time [SSRT]): (i) 11 repeated sequences of two treadmill walking bouts (TW-ISO). (ii) a single sequence of seven treadmill walking bouts (TW-CONS). (iii) a single sequence of seven outdoor walking bouts (OW-CONS). Exercise transcutaneous oxygen pressure changes were continuously recorded as an indirect measure of ischemia. An individual recovery time (IRT) beyond which WC did not substantially increase was determined in participants with a logarithmic fit. RESULTS: At the group level, mixed models showed a significant effect (P<.0.001) of recovery time on WC restoration. At the participant level, strong logarithmic relationships were found (median significant R(2)³0.78). The median SSRT corresponded to a median work-to-rest ratio >.1:1 (i.e., a lower recovery time in view of the corresponding previous walking time) and was related to unrecovered ischemia and a WC restoration level of <.80%. A median work-to-rest ratio of ≤1:2 allowed full recovery of ischemia and full restoration of WC. The IRT ratio was between 1:1 and 1:2 and corresponded to the start of recovery from ischemia. CONCLUSION: Recovery time affects the restoration level of WC during repeated maximal walking bouts in symptomatic PAD. Meaningful variations in WC restoration were related to specific levels of work-to-rest ratios.