Effects of different aerobic exercise intensities on exercise capacity, quality of life and mortality in individuals with coronary artery disease: systematic review and network meta-analysis

Objective To investigate, in adults with coronary artery disease (CAD), (i) the comparative effectiveness of aerobic exercise interventions differing in intensity and/or pattern—low-, moderate- and high-intensity continuous training (LICT, MICT, HICT) and high-intensity interval training (HIIT)—versus usual care or no exercise, and (ii) the relative effectiveness of continuous versus interval modalities, on peak oxygen uptake (VO₂peak), health-related quality of life (HRQoL), and mortality. Data sources MEDLINE (PubMed), CENTRAL, EMBASE, PEDro, and Google Scholar were searched from inception to June 2026, with grey-literature sources and reference-list screening, without language restrictions. Study selection Randomized trials were eligible per our PICO strategy. Population: adults with CAD; Intervention: aerobic exercise classified by intensity following the European Association of Preventive Cardiology; comparator: another aerobic intensity, usual care (cardiac rehabilitation without structured aerobic prescription), or control (no intervention); outcomes: VO₂peak (primary), HRQoL and mortality (secondary). Data extraction Two reviewers independently extracted data and appraised methodological quality (PEDro); risk of bias for the certainty assessment used RoB 2 within CINeMA. Data synthesis 78 trials (6287 participants) were included; 58 (3171 participants) contributed to VO₂peak, 7 (553) to HRQoL and 13 (2,563) to mortality. For VO₂peak versus usual care, HIIT (MD = 3.92 mL/kg/min, 95%CI 2.87 to 4.96), HICT (3.70, 2.58 to 4.82) and MICT (2.94, 2.24 to 3.63) showed significant improvements, whereas LICT did not; HIIT was superior to MICT in direct comparison (1.37, 0.41 to 2.33). Local inconsistency involving the MICT node was resolved in a pre-specified sensitivity analysis, after which the advantage of HICT over MICT was substantially attenuated. For HRQoL, the only significant signal (LICT) derived from a single trial and did not survive leave-one-out analysis; no intensity was shown superior to usual care. For mortality, HICT (RR = 0.51, 0.33 to 0.79) and MICT (RR = 0.63, 0.42 to 0.94) were associated with fewer events than no exercise, while HIIT did not contribute to this network. Certainty of evidence was low to very low across outcomes. Conclusions Aerobic exercise may improve VO₂peak and, at moderate-to-high intensity, may be associated with lower mortality in CAD. Any apparent superiority of higher intensities should be interpreted with caution, given the low to very low certainty, reliance on indirect evidence for several comparisons, and the absence of isocaloric protocols. Adequately powered head-to-head trials using isocaloric protocols are needed before firm intensity-specific recommendations can be made.