The effects of high-intensity interval training, Nordic walking and moderate-to-vigorous intensity continuous training on functional capacity, depression and quality of life in patients with coronary artery disease enrolled in cardiac rehabilitation: A randomized controlled trial (CRX study).

Abstract

BACKGROUND\nCoronary artery disease (CAD) patients undergoing revascularization procedures often experience ongoing, diminished functional capacity, higher rates of depression and markedly lower quality of life (QoL). In CAD patients, studies have demonstrated that high-intensity interval training (HIIT) is superior to traditional moderate-to-vigorous intensity continuous training (MICT) for improving functional capacity, whereas no differences between Nordic walking (NW) and MICT have been observed. Mental health is equally as important as physical health, yet few studies have examined the impact of HIIT and NW on depression and QoL. The purpose of this RCT was to compare the effects of 12\u202fweeks of HIIT, NW and MICT on functional capacity in CAD patients. The effects on depression severity, brain-derived neurotrophic factor (BDNF) and QoL were also examined.\n\n\nMETHODS\nCAD patients who underwent coronary revascularization procedures were randomly assigned to: (1) HIIT (4\u202f×\u202f4-minutes high-intensity bouts at 85%-95% peak heart rate [HR]), (2) NW (resting HR [RHR]\u202f+\u202f20-40\u202fbpm), or (3) MICT (RHR\u202f+\u202f20-40\u202fbpm) twice weekly for 12\u202fweeks. Functional capacity (6-min walk test [6MWT]), depression (Beck Depression Inventory-II [BDI-II]), BDNF (from a blood sample), and general (Short-Form 36 [SF-36]) and disease-specific (HeartQoL) QoL were measured at baseline and follow-up. Linear mixed-effects models for repeated measures were used to test the effects of time, group and time x group interactions.\n\n\nRESULTS\nN\u202f=\u202f135 CAD patients (aged 61\u202f±\u202f8\u202fyears; male: 85%) participated. A significant time x group interaction effect (p\u202f=\u202f0.042) showed greater increases in 6MWT distance (m) for NW (77.2\u202f±\u202f60.9) than HIIT (51.4\u202f±\u202f47.8) and MICT (48.3\u202f±\u202f47.3). BDI-II significantly improved (HIIT: -1.4\u202f±\u202f3.7, NW: -1.6\u202f±\u202f4.0, MICT: -2.3\u202f±\u202f6.0 points, main effect of time: p\u202f<\u202f0.001) whereas BDNF concentrations did not change (HIIT: -2.5\u202f±\u202f9.6, NW: -0.4\u202f±\u202f7.7, MICT: -1.2\u202f±\u202f6.4\u202fng/mL, main effect of time: p\u202f>\u202f0.05). Significant improvements in SF-36 and HeartQoL values were observed (main effects of time: p\u202f<\u202f0.05). HIIT, NW and MICT participants attended 18.3\u202f±\u202f8.0, 17.7\u202f±\u202f7.5 and 16.1\u202f±\u202f7.3 of the 24 exercise sessions, respectively (p\u202f=\u202f0.387).\n\n\nCONCLUSIONS\nAll exercise programmes (HIIT, NW, MICT) were well attended and beneficial in improving physical and mental health for CAD patients. NW was, however, statistically and clinically superior in increasing functional capacity, a predictor of future cardiovascular events.