Validity of the 6-minute walk test for assessing heart rate recovery after an exercise-based cardiac rehabilitation programme

Abstract

Objectives To compare heart rate responses in the 6-minute walk test and the treadmill exercise test before and after an exercise-based cardiac rehabilitation programme. Design Prospective cohort study. Setting Hospital-based cardiac rehabilitation programme in Hong Kong. Participants Thirty patients (mean age 62.1 ± 8.5 years, 20 males) with stable ischaemic heart disease. Interventions Eight-week exercise-based cardiac rehabilitation programme involving upper and lower limb aerobic and resistance training. Main outcome measures Six-minute walk test and treadmill exercise test before and after the exercise programme. Results Comparing parameters before and after the exercise programme, the peak heart rate in the 6-minute walk test increased (median of 105 beats per minute (bpm), interquartile range 96.8–116.5 versus 110 bpm, interquartile range 100.5–124.5, P = 0.006), while heart rate recovery improved in each 30-second interval of a 2-minute recovery period. The distance covered during the 6-minute walk increased from a mean of 486.3 m (±standard deviation 113.9 m) to 552.5 m (±standard deviation 111.9 m) ( P < 0.001). Rating of perceived exertion during the 6-minute walk test decreased from a median of 14 (interquartile range 13–15) to 13 (interquartile range 13–13) ( P = 0.001). Heart rate recovery following treadmill exercise testing improved during the 30-second periods from 60 to 90 seconds and from 90 to 120 seconds of recovery. Metabolic equivalents increased during treadmill testing from a median of 7.0 (interquartile range 5.8–8.6) to 8.6 (interquartile range 7–8.6) ( P < 0.001). Conclusions Both treadmill exercise and 6-minute walk tests demonstrated improvements in heart rate recovery and increases in achieved workload following exercise training. This suggests that the 6-minute walk test is a valid tool to assess heart rate recovery following such a programme.