Long-Term Incidence of Atrial Fibrillation and Stroke Among Cross-Country Skiers

Pathways to precision medicine: deciphering the secrets of physiological and pathological atrial enlargement

Cardiac functional, morphological, and histological analysis, coupled with liquid chromatography and mass spectrometry, of two transgenic mouse models with cardiomyocyte-specific overexpression of insulin-like growth factor 1 receptor (IGF1R) or a dominant-negative PI3K mutant (DCM-dnPI3K) revealed distinctive functional and molecular profiles during physiological (driven by IGF1R overexpression) and pathological (driven by dn-PI3K overexpression) atrial remodeling. The current study confirmed previously reported findings, including ventricular dilatation and enhanced systolic function with no evidence of arrhythmia in IGF1R model, as well as ventricular hypertrophy and decreased systolic function with intermittent atrial fibrillation in DCM-dnPI3K model. Novel findings obtained from the left atrial (LA) characterization of female mice revealed that physiological atrial enlargement resulted from increased atrial myocyte size and was associated with preserved atrial function, as determined by maintained LA ejection fraction (EF). The proteomic profile of IGF1R transgenic (Tg) mice was enriched for metabolic remodeling and showed a protein expression pattern similar to that of healthy human atria; on the other hand, pathological atrial enlargement resulted from increased atrial fibrosis with normal myocyte size and was associated with impaired atrial function due to a reduced LA EF. The proteomic profile of DCM-dnPI3K mice was enriched to both metabolic and structural remodeling and showed a protein expression pattern similar to that of human AF atria.

Training Intensity Distribution of a 7-Day HIIT Shock Microcycle: Is Time in the "Red Zone" Crucial for Maximizing Endurance Performance? A Randomized Controlled Trial

BACKGROUND

Various studies have shown that the type of intensity measure affects training intensity distribution (TID) computation. These conclusions arise from studies presenting data from meso- and macrocycles, while microcycles, e.g., high-intensity interval training shock microcycles (HIIT-SM) have been neglected so far. Previous literature has suggested that the time spent in the high-intensity zone, i.e., zone 3 (Z3) or the "red zone", during HIIT may be important to achieve improvements in endurance performance parameters. Therefore, this randomized controlled trial aimed to compare the TID based on running velocity (TIDV), running power (TIDP) and heart rate (TIDHR) during a 7-day HIIT-SM. Twenty-nine endurance-trained participant were allocated to a HIIT-SM consisting of 10 HIIT sessions without (HSM, n = 9) or with (HSM + LIT, n = 9) additional low-intensity training or a control group (n = 11). Moreover, we explored relationships between time spent in Z3 determined by running velocity (Z3V), running power (Z3P), heart rate (Z3HR), oxygen uptake ( Z 3 V ˙ O 2 ) and changes in endurance performance.

RESULTS

Both intervention groups revealed a polarized pattern for TIDV (HSM: Z1: 38 ± 17, Z2: 16 ± 17, Z3: 46 ± 2%; HSM + LIT: Z1: 59 ± 18, Z2: 14 ± 18, Z3: 27 ± 2%) and TIDP (Z1: 50 ± 8, Z2: 14 ± 11, Z3: 36 ± 7%; Z1: 62 ± 15, Z2: 12 ± 16, Z3: 26 ± 2%), while TIDHR (Z1: 48 ± 13, Z2: 26 ± 11, Z3: 26 ± 7%; Z1: 65 ± 17, Z2: 22 ± 18, Z3: 13 ± 4%) showed a pyramidal pattern. Time in Z3HR was significantly less compared to Z3V and Z3P in both intervention groups (all p < 0.01). There was a time x intensity measure interaction for time in Z3 across the 10 HIIT sessions for HSM + LIT (p < 0.001, pη2 = 0.30). Time in Z3V and Z3P within each single HIIT session remained stable over the training period for both intervention groups. Time in Z3HR declined in HSM from the first (47%) to the last (28%) session, which was more pronounced in HSM + LIT (45% to 16%). A moderate dose-response relationship was found for time in Z3V and changes in peak power output (rs = 0.52, p = 0.028) as well as time trial performance (rs = - 0.47, p = 0.049) with no such associations regarding time in Z3P, Z3HR, and Z 3 V ˙ O 2 .

CONCLUSION

The present study reveals that the type of intensity measure strongly affects TID computation during a HIIT-SM. As heart rate tends to underestimate the intensity during HIIT-SM, heart rate-based training decisions should be made cautiously. In addition, time in Z3V was most closely associated with changes in endurance performance. Thus, for evaluating a HIIT-SM, we suggest integrating a comprehensive set of intensity measures. Trial Registration Trial register: Clinicaltrials.gov, registration number: NCT05067426.

2024 HRS expert consensus statement on arrhythmias in the athlete: Evaluation, treatment, and return to play

Youth and adult participation in sports continues to increase, and athletes may be diagnosed with potentially arrhythmogenic cardiac conditions. This international multidisciplinary document is intended to guide electrophysiologists, sports cardiologists, and associated health care team members in the diagnosis, treatment, and management of arrhythmic conditions in the athlete with the goal of facilitating return to sport and avoiding the harm caused by restriction. Expert, disease-specific risk assessment in the context of athlete symptoms and diagnoses is emphasized throughout the document. After appropriate risk assessment, management of arrhythmias geared toward return to play when possible is addressed. Other topics include shared decision-making and emergency action planning. The goal of this document is to provide evidence-based recommendations impacting all areas in the care of athletes with arrhythmic conditions. Areas in need of further study are also discussed.

Health Benefits of Different Sports: a Systematic Review and Meta-Analysis of Longitudinal and Intervention Studies Including 2.6 Million Adult Participants

BACKGROUND

Several reviews have examined the health benefits of participation in specific sports, such as baseball, cricket, cross-country skiing, cycling, downhill skiing, football, golf, judo, rugby, running and swimming. However, new primary studies on the topic have recently been published, and the respective meta-analytic evidence needs to be updated.

OBJECTIVES

To systematically review, summarise and appraise evidence on physical health benefits of participation in different recreational sports.

METHODS

Searches for journal articles were conducted in PubMed/MEDLINE, Scopus, SpoLit, SPORTDiscus, Sports Medicine & Education Index and Web of Science. We included longitudinal and intervention studies investigating physical health outcomes associated with participation in a given sport among generally healthy adults without disability.

RESULTS

A total of 136 papers from 76 studies conducted among 2.6 million participants were included in the review. Our meta-analyses of available evidence found that: (1) cycling reduces the risk of coronary heart disease by 16% (pooled hazard ratio [HR] = 0.84; 95% confidence interval [CI]: 0.80, 0.89), all-cause mortality by 21% (HR = 0.79; 95% CI: 0.73, 0.84), cancer mortality by 10% (HR = 0.90; 95% CI: 0.85, 0.96) and cardiovascular mortality by 20% (HR = 0.80; 95% CI: 0.74, 0.86); (2) football has favourable effects on body composition, blood lipids, fasting blood glucose, blood pressure, cardiovascular function at rest, cardiorespiratory fitness and bone strength (p < 0.050); (3) handball has favourable effects on body composition and cardiorespiratory fitness (p < 0.050); (4) running reduces the risk of all-cause mortality by 23% (HR = 0.77; 95% CI: 0.70, 0.85), cancer mortality by 20% (HR = 0.80; 95% CI: 0.72, 0.89) and cardiovascular mortality by 27% (HR = 0.73; 95% CI: 0.57, 0.94) and improves body composition, cardiovascular function at rest and cardiorespiratory fitness (p < 0.010); and (5) swimming reduces the risk of all-cause mortality by 24% (HR = 0.76; 95% CI: 0.63, 0.92) and improves body composition and blood lipids (p < 0.010).

CONCLUSIONS

A range of physical health benefits are associated with participation in recreational cycling, football, handball, running and swimming. More studies are needed to enable meta-analyses of health benefits of participation in other sports. PROSPERO registration number CRD42021234839.

Influence of exercise training on the left atrium: implications for atrial fibrillation, heart failure, and stroke

The left atrium (LA) plays a critical role in receiving pulmonary venous return and modulating left ventricular (LV) filling. With the onset of exercise, LA function contributes to the augmentation in stroke volume. Due to the growing focus on atrial imaging, there is now evidence that structural remodeling and dysfunction of the LA is associated with adverse outcomes including incident cardiovascular disease. In patients with established disease, pathological changes in atrial structure and function are associated with exercise intolerance, increased hospital admissions and mortality, independent of left ventricular function. Exercise training is widely recommended in patients with cardiovascular disease to improve patient outcomes and maintain functional capacity. There are widely documented changes in LV function with exercise, yet less attention has been given to the LA. In this review, we first describe LA physiology at rest and during exercise, before exploring its association with cardiac disease outcomes including atrial fibrillation, heart failure, and stroke. The adaptation of the LA to short- and longer-term exercise training is evaluated through review of longitudinal studies of exercise training in healthy participants free of cardiovascular disease and athletes. We then consider the changes in LA structure and function among patients with established disease, where adverse atrial remodeling may be implicated in the disease process. Finally, we consider important future directions for assessment of atrial structure and function using novel imaging modalities, in response to acute and chronic exercise.

Can the Heart Get an Overuse Sports Injury?

Can the Heart Get an Overuse Sports Injury?Recent studies suggest that vigorous endurance exercise increases markers of cardiomyocyte injury and that lifelong endurance exercise may increase myocardial scarring, coronary artery atherosclerosis, AF, and aortic dilatation. This review summarizes the evidence linking these conditions with physical exertion and an approach to their management.

Impact of Exercise on Cerebrovascular Physiology and Risk of Stroke

Ischemic heart disease and stroke are the number 1 and number 2 causes of death worldwide, respectively. A lifelong commitment to exercise reduces the risk of these adverse events and is also associated with several cardiometabolic improvements, including reductions in blood pressure, cholesterol, and inflammatory markers, as well as improved glucose control. Routine exercise also reduces the risk of developing comorbidities that increase the risk of cardiovascular or cerebrovascular disease. While the benefits of a lifelong commitment to exercise are well documented, there is a complex interaction between exercise and stroke risk, such that the risk of ischemic or hemorrhagic stroke may increase acutely during or immediately following exercise. In this article, we discuss the physiological responses to different types of exercise, as well as the determinants of resting and exertional cerebrovascular perfusion, and explore the complex interaction between atrial fibrillation, exercise, and stroke risk. Finally, we highlight the increased risk of stroke during different types of exercise, as well as factors that may alleviate this risk.

Atrial structure and function in middle-aged, physically-active males and females: A cardiac magnetic resonance study

Recent studies have reported on an association between endurance sport, atrial enlargement and the development of lone atrial fibrillation in younger, male cohorts. The atrial morphology and function of middle‐aged, physically‐active males and females have not been well studied. We hypothesized that middle‐aged males would demonstrate larger left atrium (LA) and right atrium (RA) volumes compared to females, but atrial function would not differ. LA and RA volume and function were evaluated at rest in healthy adults, using a standardized 3.0Tesla cardiac magnetic resonance protocol. Physical activity, medical history, and maximal oxygen consumption (V˙O2peak) were also assessed. Physically‐active, middle‐aged men (n = 60; 54 ± 5 years old) and women (n = 30; 54 ± 5 years old) completed this study. Males had a higher body mass index, systolic blood pressure, and V˙O2peak than females (p < .05 for all), despite similar reported physical activity levels. Absolute and BSA and height‐indexed LA and RA maximum volumes were higher in males relative to females, despite no differences in ejection fractions (p < .05 for all). In multivariable regression, male sex p < .001) and V˙O2peak (p = .004) were predictors of LA volume (model R² = 0.252), whereas V˙O2peak (p < .001), male sex (p = .03), and RV EF (p < .05) were predictors of RA volume (model R² = 0.377). While middle‐aged males exhibited larger atrial volumes relative to females, larger, prospective studies are needed to explore the magnitude of physiologic atrial remodeling and functional adaptations in relation to phenotypic factors.

Can too much exercise be dangerous: what can we learn from the athlete's heart?

Exercise prevents and aids treatment of coronary heart disease, hypertension, heart failure, diabetes mellitus, obesity and depression, reduces cardiac events and improves survival. However, evidence suggests that the relationship between exercise and mortality may be curvilinear, with modest additional benefit at higher levels. Intensive exercise has also been associated with increased atrial fibrillation risk, although its clinical implications are not well understood. Other proposed adverse effects of exercise on the heart, including reduced right ventricular function, elevated cardiac biomarkers, myocardial fibrosis and coronary artery calcification, are less substantiated. Current evidence cannot affirm that extreme exercise is dangerous and future studies should combine large cohorts to obtain a statistically reliable limit. Associations between features of the athlete's heart and cardiovascular morbidity and mortality should also be explored.

Association between exercise habits and stroke, heart failure, and mortality in Korean patients with incident atrial fibrillation: A nationwide population-based cohort study

BACKGROUND

There is a paucity of information about cardiovascular outcomes related to exercise habit change after a new diagnosis of atrial fibrillation (AF). We investigated the association between exercise habits after a new AF diagnosis and ischemic stroke, heart failure (HF), and all-cause death.

METHODS AND FINDINGS

This is a nationwide population-based cohort study using data from the Korea National Health Insurance Service. A retrospective analysis was performed for 66,692 patients with newly diagnosed AF between 2010 and 2016 who underwent 2 serial health examinations within 2 years before and after their AF diagnosis. Individuals were divided into 4 categories according to performance of regular exercise, which was investigated by a self-reported questionnaire in each health examination, before and after their AF diagnosis: persistent non-exercisers (30.5%), new exercisers (17.8%), exercise dropouts (17.4%), and exercise maintainers (34.2%). The primary outcomes were incidence of ischemic stroke, HF, and all-cause death. Differences in baseline characteristics among groups were balanced considering demographics, comorbidities, medications, lifestyle behaviors, and income status. The risks of the outcomes were computed by weighted Cox proportional hazards models with inverse probability of treatment weighting (IPTW) during a mean follow-up of 3.4 ± 2.0 years. The new exerciser and exercise maintainer groups were associated with a lower risk of HF compared to the persistent non-exerciser group: the hazard ratios (HRs) (95% CIs) were 0.95 (0.90-0.99) and 0.92 (0.88-0.96), respectively (p < 0.001). Also, performing exercise any time before or after AF diagnosis was associated with a lower risk of mortality compared to persistent non-exercising: the HR (95% CI) was 0.82 (0.73-0.91) for new exercisers, 0.83 (0.74-0.93) for exercise dropouts, and 0.61 (0.55-0.67) for exercise maintainers (p < 0.001). For ischemic stroke, the estimates of HRs were 10%-14% lower in patients of the exercise groups, yet differences were statistically insignificant (p = 0.057). Energy expenditure of 1,000-1,499 MET-min/wk (regular moderate exercise 170-240 min/wk) was consistently associated with a lower risk of each outcome based on a subgroup analysis of the new exerciser group. Study limitations include recall bias introduced due to the nature of the self-reported questionnaire and restricted external generalizability to other ethnic groups.

CONCLUSIONS

Initiating or continuing regular exercise after AF diagnosis was associated with lower risks of HF and mortality. The promotion of exercise might reduce the future risk of adverse outcomes in patients with AF.

The Underrepresentation of Females in Studies Assessing the Impact of High-Dose Exercise on Cardiovascular Outcomes: a Scoping Review

High-dose exercise-induced cardiac outcomes may vary between sexes. However, many studies investigating the cardiovascular effects of high-dose exercise have excluded or under-recruited females. This scoping review aimed to describe the recruitment of females in studies assessing the impact of high-dose exercise on cardiovascular outcomes and describe how this has changed over time. This scoping review followed the protocol outlined by Arksey and O’Malley and is reported as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews (PRISMA-ScR) guidelines. The OVID and EMBASE databases were searched for studies that assessed the effects of high-dose exercise on cardiovascular outcomes. Both professional and nonprofessional groups were included. The review found 2973 studies, and 250 met the inclusion criteria including cumulatively 17,548,843 subjects. Over half the studies (n = 127) excluded females entirely, and only 8 (3.2%) studies recruited all-female participants. The overall mean percentage of females recruited was 18.2%. The mean percentage was 14.5% in studies conducted before 2011 and 21.8% in studies conducted after 2011. Females are an underrepresented group in studies assessing the cardiovascular outcomes related to high-dose exercise. As cardiovascular outcomes vary between sexes, translating findings from a largely male-based evidence may not be appropriate. Future investigators should aim to establish and overcome barriers to female recruitment.

Physical activity, cardiorespiratory fitness, and cardiovascular outcomes in individuals with atrial fibrillation: the HUNT study

AIMS

Atrial fibrillation (AF) confers higher risk of mortality and morbidity, but the long-term impact of physical activity (PA) and cardiorespiratory fitness (CRF) on outcomes in AF patients is unknown. We, therefore, examined the prospective associations of PA and estimated CRF (eCRF) with all-cause mortality, cardiovascular disease (CVD) mortality, morbidity and stroke in individuals with AF.

METHODS AND RESULTS

We followed 1117 AF patients from the HUNT3 study in 2006-08 until first occurrence of the outcomes or end of follow-up in November 2015. We used Cox proportional hazard regression to examine the prospective associations of self-reported PA and eCRF with the outcomes. Atrial fibrillation patients meeting PA guidelines had lower risk of all-cause [hazard ratio (HR) 0.55, 95% confidence interval (CI) 0.41-0.75] and CVD mortality (HR 0.54, 95% CI 0.34-0.86) compared with inactive patients. The respective HRs for CVD morbidity and stroke were 0.78 (95% CI 0.58-1.04) and 0.70 (95% CI 0.42-1.15). Each 1-metabolic equivalent task (MET) higher eCRF was associated with a lower risk of all-cause (HR 0.88, 95% CI 0.81-0.95), CVD mortality (HR 0.85, 95% CI 0.76-0.95), and morbidity (HR 0.88, 95% CI 0.82-0.95).

CONCLUSION

Higher PA and CRF are associated with lower long-term risk of CVD and all-cause mortality in individuals with AF. The findings support a role for regular PA and improved CRF in AF patients, in order to combat the elevated risk for mortality and morbidity.

The effects of endurance exercise on the heart: panacea or poison?

Regular aerobic physical exercise of moderate intensity is undeniably associated with improved health and increased longevity, with some studies suggesting that more is better. Endurance athletes exceed the usual recommendations for exercise by 15-fold to 20-fold. The need to sustain a large cardiac output for prolonged periods is associated with a 10-20% increase in left and right ventricular size and a substantial increase in left ventricular mass. A large proportion of endurance athletes have raised levels of cardiac biomarkers (troponins and B-type natriuretic peptide) and cardiac dysfunction for 24-48 h after events, but what is the relevance of these findings? In the longer term, some endurance athletes have an increased prevalence of coronary artery disease, myocardial fibrosis and arrhythmias. The inherent association between these 'maladaptations' and sudden cardiac death in the general population raises the question of whether endurance exercise could be detrimental for some individuals. However, despite speculation that these abnormalities confer an increased risk of future adverse events, elite endurance athletes have an increased life expectancy compared with the general population.