Editorial comments: focus on exercise in sport cardiology and cardiac rehabilitation

This issue of the European Journal of Preventive Cardiology focuses on the role of physical activity in preventing cardiovascular disease and sport-related cardiac adverse events in both the general population and specific subgroups. Pre-participation screening (PPS) aims primarily to prevent sudden death (SD) in athletes by identifying cardiovascular diseases (CVD) at risk of malignant ventricular arrhythmias (VAs) during their pre-symptomatic phase.1 The PPS for competitive activity in Italy and in Europe is mainly based on clinical evaluation and 12-lead standard surface electrocardiogram (ECG) interpretation. In the last few years, cardiac magnetic resonance (CMR) has demonstrated high accuracy in the study of cardiac structure and function, in addition to its unique ability to perform cardiac tissue characterization becoming the gold standard method in this field. Sciarra et al.2 demonstrated that 7 parameters of 12-lead ECG can be an important screening tool for the presence of a non-ischaemic left ventricular scar in athletes with right bundle branch block morphology non-sustained VAs. In Italy, the Balduzzi law was proclaimed in 2012 with the aim of ensuring prevention of SD among athletes. The law mandated that all sports facilities should have a defibrillator and trained staff for cardiopulmonary resuscitation (CPR). However, this law only came into effect in 2015. Gianni et al.3 tried to assess the impact of this law on SD in sports in Lombardy, Italy. In comparison with the period from 2011 to 2014, the presence of defibrillators in sports facilities from 2015 to 2019 led to a higher percentage of successful defibrillation and a greater likelihood of return of spontaneous circulation. Although long-term outcome data are not available, the regulation in this area has certainly improved the landscape of SD in sports. Consistent aerobic exercise leads to changes in the structure of the heart muscle, including thicker left ventricular walls and larger heart chambers. These changes allow for a greater amount of blood to be pumped with each heartbeat during exercise, improving overall heart function and exercise capacity. Left ventricular mass (LVM), which reflects overall cardiac structure, is one such measure influenced by aerobic exercise. Short-term detraining has been shown to reduce blood volume, stroke volume, and ultimately maximal cardiac output and aerobic capacity, while detraining for periods longer than 4 weeks has been reported to be associated with significant reductions in cardiac dimensions.4 It is not well-defined whether the reduction in myocardial mass occurs after a few weeks of detraining or after a longer period. Massarotto et al.5 in 194 endurance-trained individuals with detraining periods ranging from 1.4 to 15 weeks reported that LVM significantly decreases following only a few weeks of detraining. The extent of the reduction in LVM was linked to the duration of detraining and was more pronounced in highly trained athletes. Additionally, a correlation was observed between the decrease in LVM and the decrease in exercise capacity. Further research may offer a deeper understanding of how sex, age, and the type of detraining affect changes in LVM among endurance-trained individuals. Cardiopulmonary exercise testing (CPET) is typically used to assess their cardiorespiratory fitness (CRF). However, interpreting CPET results, particularly identifying the anaerobic threshold (AT) and measuring peak oxygen uptake (peak VO2), requires expertise and carries risks due to the strenuous exercise involved. Watanabe et al.6 developed deep-learning models as a promising solution for real-time analysis of CPET results, providing accurate identification of AT and prediction of peak VO2. These models have the potential to serve as valuable tools for clinicians in assessing patients’ CRF during CPET, thereby expanding the utility of this diagnostic procedure. Meeting the recommended 150 min per week of moderate-to-vigorous physical activity (PA) is strongly recommended for preventing CVD.7–9 However, PA levels vary throughout the lifetime, and this complexity has not been fully explored in published studies. To address this, Huang et al.10 analysed data from the CARDIA study, which followed participants for 15 years to assess their long-term PA levels during young adulthood and to collect cardiovascular events later in life (follow-up 18.9 years). A clear link between consistent PA levels during young adulthood and reduced risk of events later in life was present. Participants who maintained PA at or above the recommended level for over 75% of the time during their young adulthood experienced greater cardiovascular benefits. However, it’s worth noting that the study’s findings of lower CVD risk among those with the highest PA levels may have been influenced by the relatively younger age and limited sample size of the study population. Moreover, the study suggests that older individuals or those with existing CVD may derive even greater benefits from regular PA compared with younger individuals with lower cardiovascular risk. Although CRF is a well-established prognostic value in different CVD, the relationship between changes in CRF and hospital admissions due to CVD and due to all causes in the general population have been poorly investigated. Griffin et al.11 measured peak VO2 in 91 140 adults (41.5% women) and observed maintaining or increasing CRF was linked to a 9% reduction in the risk of CVD hospital admissions and a 7% decrease in the risk of all-cause admissions, compared with those experiencing a decline in CRF. Moreover, boosting CRF was associated with even greater risk reductions. Notably, individuals who had previously been hospitalized and managed to increase their CRF saw substantial risk reductions for future admissions, with a 20% lower risk of CVD hospitalizations and a 14% lower risk of all-cause admissions. Although leisure time PA (LTPA) is widely recognized as beneficial for cardiovascular health, recent studies suggest that occupational PA (OPA) might have contrasting effects, due to increased cardiovascular strain. High levels of self-reported OPA, such as continuous walking or lifting at work, have been linked to increased risk of CVD and mortality, especially in individuals with existing heart conditions or low fitness levels. This conflicting relationship between LTPA and OPA has been termed the ‘PA health paradox’. According to Quinn et al.,12 prolonged exposure to high OPA over 25 years was associated with lower left ventricular ejection fraction and higher left ventricular end-systolic volume index. These associations may be more evident in men, individuals with higher education levels, and those with low levels of LTPA. However, further research is necessary to confirm these findings. Traditionally, exercise studies have mainly focused on continuous training for improving CRF. However, high-intensity interval training (HIIT) has gained popularity as a time-efficient alternative. High-intensity interval training involves short bursts of high-intensity exercise interspersed with rest or active recovery periods. A review by Cadenas-Sanchez et al.13 aimed to assess the effects of HIIT protocols on CRF and identify patterns in HIIT modalities. Despite a high variability in protocols, three main HIIT modalities were identified: HIIT-normal mixed, HIIT-long running, and HIIT-short cycling. All modalities significantly improved CRF regardless of factors like sex, weight status, or baseline PA level. Future research should adhere to the guidelines for reporting HIIT protocols outlined in this study and consider incorporating strength training as another HIIT modality. Cardiorespiratory fitness measured by CPET is a strong predictor of cardiovascular health and mortality, but CPET may not always be practical or suitable, especially for older or frail patients. In recent years, various methods, both exercise-based and non-exercise-based, have been explored to estimate peak VO2. Van Leunen et al.14 aimed to assess the accuracy of two self-reported questionnaires, the FitMáx questionnaire and The Fitness Calculator, in predicting peak VO2 among chronic heart failure (CHF) patients. Results showed that FitMáx demonstrated greater accuracy in predicting peak VO2 compared with HFC. This could be attributed to FitMáx offering more options for PA evaluation, allowing for better differentiation between activity levels. However, despite the promising results, there was still considerable variability in the estimates provided by the self-reported questionnaires. Exercise-based cardiac rehabilitation reduces the risk of hospital admissions and improves the quality of life (QoL), aerobic and walking capacity, and muscle strength in patients with CHF. In coronary artery disease, moderate-intensity (MI) resistance exercise training (combined with endurance exercise training) is superior to low-intensity (LI) resistance training to improve muscle strength, but no data are available in patients with CHF.15 Gojevic et al.16 demonstrated that LI and MI resistance exercise training, combined with endurance exercise training, similarly improves peak VO2, walking capacity, and muscle strength, but LI resistance exercise training might be superior in improving QoL in patients with CHF. Currently, there is a lack of effective therapy to enhance exercise capacity in Fontan patients. Scheffers et al.17 explored the potential benefits of leg-focused high-weight resistance training combined with a high-protein diet in paediatric Fontan patients. Over a 12-week period, 27 participants completed the training programme, which resulted in significant improvements in peak VO2 and peak workload compared with the control period. Additionally, there were notable increases in indexed single ventricle stroke volume and inferior vena cava flow. Furthermore, improvements were observed in self-reported QoL in terms of physical functioning and changes in health. Overall, these findings suggest that a 12-week leg-focused high-weight resistance training programme can effectively enhance exercise capacity, cardiac function, muscle strength, and QoL in older Fontan children. Regular exercise is suggested as first-line therapy for patients with peripheral arterial disease (PAD). A systematic review18 aimed to compile and analyse findings from existing meta-analyses on the effects of regular exercise in individuals with PAD. Supervised aerobic exercise enhanced various walking-related parameters and aerobic capacity, while resistance exercise improved lower limb strength. However, evidence regarding other outcomes like haemodynamic parameters was inconclusive, and further research is needed to understand the effects of exercise on PA levels, adverse events, and mortality.