New venues to study the effects of exercise on quality of life and mental health in coronary artery disease

This commentary refers to ‘Exercise type and settings, quality of life, and mental health in coronary artery disease: a network meta-analysis' by A. Toval et al., https://doi.org/10.1093/eurheartj/ehae870 and the discussion piece ‘Beyond modality: unaddressed variables and comorbidities in exercise interventions for coronary artery disease', by J. Huang, https://doi.org/10.1093/eurheartj/ehaf487. We thank Dr Jian Huang for the insightful commentary highlighting the importance of exercise training characteristics, such as frequency, duration and type of supervision, and the impact of comorbidities. We agree that exercise characteristics might impact the effect on brain-related outcomes as we see its effects on cardiovascular outcomes.1 It is important to note that we performed secondary analyses on total duration and training hours.2 These analyses showed similar effect estimates between longer vs. shorter intervention duration (≤12 vs. >12 weeks) and between more vs. less training hours (≤24 vs. >24 h during intervention). We did not make a distinction based on training frequency, because most studies prescribed exercise 2–3 times/week in at least one intervention arm (80%) and only a few >3 times/week (19%) making it unfeasible to run additional network meta-analyses. Additionally, population studies have shown that so-called ‘weekend warriors’ (i.e. 1–2 days/week active) have similar risk reductions compared with regularly activity individuals (i.e. ≥3 days/week active) when both groups performed guideline-adherent physical activity volumes.3 Moreover, exercise volume, defined as MET-minutes/week, is important and the literature showed that higher exercise volumes are associated with larger cardiovascular health benefits.1,4 Although the effects of exercise intensity and the number of training hours did not differentiate in our study,2 future studies should explore the dose–response relationship between exercise volume and brain-related outcomes. To do so, we want to encourage trialist to report detailed exercise characteristics following the Consensus on Exercise Reporting Template (CERT).5 Unfortunately, we encountered that multiple CERT categories were poorly and heterogeneously reported, which refrained us from performing more detailed analyses on exercise intervention characteristics (e.g. time, frequency, intensity, volume, type of supervision, adherence, and compliance).