Brief Vigorous Stair Climbing Effectively Improves Cardiorespiratory Fitness in Patients With Coronary Artery Disease: A Randomized Trial

Abstract

Background: Cardiac rehabilitation exercise reduces the risk of secondary cardiovascular disease. Interval training is a time-efficient alternative to traditional cardiac rehabilitation exercise and stair climbing is an accessible means. We aimed to assess the effectiveness of a high-intensity interval stair climbing intervention on improving cardiorespiratory fitness ( $\dot{\text{V}}{\text{O}}_{2\text{peak}}$ ) compared to standard cardiac rehabilitation care. Methods: Twenty participants with coronary artery disease (61 ± 7 years, 18 males, two females) were randomly assigned to either traditional moderate-intensity exercise (TRAD) or high-intensity interval stair climbing (STAIR). $\dot{\text{V}}{\text{O}}_{2\text{peak}}$ was assessed at baseline, following 4 weeks of six supervised exercise sessions and after 8 weeks of ~24 unsupervised exercise sessions. TRAD involved a minimum of 30 min at 60-80%HR_peak, and STAIR consisted of three bouts of six flights of 12 stairs at a self-selected vigorous intensity (~90 s/bout) separated by recovery periods of walking (~90 s). This study was registered as a clinical trial at clinicaltrials.gov (NCT03235674). Results: Two participants could not complete the trial due to the time commitment of the testing visits, leaving n = 9 in each group who completed the interventions without any adverse events. $\dot{\text{V}}{\text{O}}_{2\text{peak}}$ increased after supervised and unsupervised training in comparison to baseline for both TRAD [baseline: 22.9 ± 2.5, 4 weeks (supervised): 25.3 ± 4.4, and 12 weeks (unsupervised): 26.5 ± 4.8 mL/kg/min] and STAIR [baseline: 21.4 ± 4.5, 4 weeks (supervised): 23.4 ± 5.6, and 12 weeks (unsupervised): 25 ± 6.2 mL/kg/min; p (time) = 0.03]. During the first 4 weeks of training (supervised) the STAIR vs. TRAD group had a higher %HR_peak (101 ± 1 vs. 89 ± 1%; p ≤ 0.001), across a shorter total exercise time (7.1 ± 0.1 vs. 36.7 ± 1.1 min; p = 0.009). During the subsequent 8 weeks of unsupervised training, %HR_peak was not different (87 ± 8 vs. 96 ± 8%; p = 0.055, mean ± SD) between groups, however, the STAIR group continued to exercise for less time per session (10.0 ± 3.2 vs. 24.2 ± 17.0 min; p = 0.036). Conclusions: Both brief, vigorous stair climbing, and traditional moderate-intensity exercise are effective in increasing $\dot{\text{V}}{\text{O}}_{2\text{peak}}$ , in cardiac rehabilitation exercise programmes.

Keywords: cardiac rehabilitation; cardiorespiratory fitness; coronary artery disease; exercise; high intensity interval training.

Figure 1

Illustration of the study timeline and exercise interventions. Participants were recruited and completed the baseline testing visit and then were randomized to either the traditional moderate-intensity continuous training (TRAD) or stair climbing high intensity interval training (STAIR) groups. The participants completed six sessions of supervised exercise at the Cardiac Health and Rehabilitation Center (CHRC) and then underwent the second testing visit. Thereafter, the participants completed unsupervised exercise for an additional 8 weeks and then completed the final testing visit. TRAD consisted of a minimum of 30 min of moderate intensity exercise at 60–80% peak heart rate. STAIR consisted of three bouts of climbing a single flight of stairs 6 times at a self-selected, but vigorous pace (14–15/20 RPE) separated by a ~90 s periods of active recovery at a comfortable pace (~7 min total of high and low intensity intervals). For both exercise protocols heart rate was monitored continuously throughout the exercise session. Each of the estimated exercise times include the 10 min warm-up and 5 min cooldown. RPE and HR were recorded on paper at the specific timepoints indicated by a green dot. RPE, rating of perceived exertion; HR, heart rate. The hospital icon was created by Nibras@design, the nounproject.com. All other icons were developed using Microsoft PowerPoint (version 16.45 for Mac).

Figure 2

CONSORT flow diagram. CONSORT, Consolidated Standards of Reporting Trials; TRAD, Traditional moderate-intensity continuous exercise training; STAIR, stair climbing-based high-intensity interval training.

Figure 3

V°O₂peak improvements following 4 weeks of supervised and 8 additional weeks of unsupervised exercise training of both TRAD and STAIR programs. Data is reported as a boxplot with the minimum, median and maximum values represented (n = 9/group). BL, Baseline; *significantly different from Baseline (p = 0.001), using a Two-way repeated measures ANOVA.