Elsevier

International Journal of Cardiology

Volume 223, 15 November 2016, Pages 325-330
International Journal of Cardiology

Atrial chamber remodelling in healthy pre-adolescent athletes engaged in endurance sports: A study with a longitudinal design. The CHILD study

https://doi.org/10.1016/j.ijcard.2016.08.231Get rights and content

Abstract

Aims

Previous studies investigated the exercise-induced adaptation of left (LA) and right atrium (RA) in adults, but little is known about respective changes in the growing heart of children. We aimed to longitudinally investigate the effects of endurance training on biatrial remodelling in preadolescent athletes.

Methods and results

Ninety-four children (57 endurance athletes, 37 sedentary controls; mean age 10.8 ± 0.2 and 10.2 ± 0.2 years, respectively) were evaluated at baseline and after 5 months by ECG and by two-dimensional, three-dimensional (3D) and speckle-tracking echocardiography. Athletes were trained at least 10 h/week. The resting heart rate was lower in athletes (p = 0.046) and decreased further after training (p < 0.0001). Neither athletes nor controls had ECG evidence for LA or RA enlargement. At baseline, indexed LA volumes did not differ between groups (p = 0.14) but indexed RA dimensions were larger in athletes (p = 0.007). After 5 months, indexed LA volumes increased in athletes but not in controls (p < 0.0001, p = 0.29; respectively) while indexed RA volumes increased in both groups (p < 0.0001, p = 0.018; respectively). At the same time, slight differences in biatrial reservoir and contractile function were found either in athletes, as demonstrated by speckle-tracking echocardiography, but 3D-derived LA and RA ejection fraction remained stable in both groups.

Conclusion

Endurance training influences the growing heart of preadolescent athletes with an additive increase in biatrial size, suggesting that morphological adaptations can occur also in the early phases of the sports career. Training-induced remodelling was associated with a preserved biatrial function, supporting the hypothesis of a physiological remodelling.

Introduction

The importance of assessing right (RA) and left atrial (LA) size by echocardiography in children has increasingly been recognized. Enlarged RA can provide relevant hints for the diagnosis, follow-up, and indication for intervention [1], [2], [3]. Also LA size is a recognized key determinant of cardiac function and recent evidence suggests that in childhood obesity independently influences LA size [4], [5] and may represent a possible marker of increased cardiovascular risk [5]. Biatrial enlargement is considered an early marker of ventricular disease, as well as physiological response to increases in loading conditions, as is the case in the ‘athlete's heart’ [6], [7], [8], [9]. While previous cross-sectional and longitudinal studies reported the impact of exercise on biatrial functional and dimensional remodelling in adults [10], [11], [12], little is known about respective changes in the growing heart in the early phases of sports careers. Data from adult studies cannot be directly transferred to preadolescent athletes, as they are physically less mature and are usually exposed to a shorter period of training compared to adults [13]. Furthermore, very few longitudinal studies have examined the effect of endurance training on cardiac measurements in preadolescent athletes [14], [15], [16], with controversial results. Considering the increasing number of children involved in sports, the trend to more intensive physical training, and the decreasing age at which young athletes are encouraged to train intensively for sporting competitions, a better understanding of their morphological and functional adaptation is extremely important and imposes the need for the clinical characterization of their response to exercise.

Therefore, the aim of this longitudinal study was: i) to evaluate potential differences in atrial measurements in preadolescent athletes under control conditions; ii) to assess the extent of increase in atrial measurements after 5 months of training compared to no training; and iii) to determine whether atrial changes are related to those of myocardial function assessed by speckle-tracking echocardiography (STE).

Section snippets

Study population

Sixty-two pre-adolescent male competitive endurance athletes practising swimming in a regional level of mean age 10.8 ± 0.2 years [9], [10], [11], [12], [13] were enrolled in this study. They were trained once a day, for 5–6 days a week. A typical training started with 30–45 min of dry-land exercises (gymnastics and stretching) followed by 75–90 min swimming. The total training programme consisted of 10% of warming-up exercises, 15% of technical training, and 75% of three-staged aerobic exercises. In

Results

The demographic characteristics of athletes and controls are reported in Table 1. At baseline there were no significant differences between athletes and controls for height, weight, and BSA. After 5 months, height, weight, and BSA all increased in both athletes and in controls (p < 0.0001 for both).

Based on the Tanner's Scale, 46% (n = 25) of athletes were at stage 1 (pre-puberty) and the rest were at stages 2–5 (puberty), at baseline. 9% (n = 5) of athletes had reached sexual maturity and 37%

Discussion

The present study is the first to longitudinally characterize biatrial response to training in preadolescent athletes. We demonstrated that: i) at baseline indexed biatrial structural measurements were not different between preadolescent athletes, evaluated after 3 months of detraining, and their sedentary counterparts; ii) after 5 months, LA size significantly increased in athletes and these findings were consistent irrespective of technique used (2D or 3D echocardiography); however, RA size did

Limitations

While the present study suggests that training can affect biatrial size and function in pre-adolescents, it is important to highlight that this finding may be sport specific, it is possible that the influence of age and the related hormonal and growth factors may have a different impact in anaerobic sports. Also, we cannot exclude that the observed response to training may reflect genetic traits which predisposed the trained children to a more favourable and relevant adaptation. Our results

Conclusions

Intensive endurance training affects the growing heart of preadolescent athletes with an additive increase in biatrial size, suggesting that morphological adaptations can occur also in the early phases of the sports career of an athlete. Five months of intensive training were associated with a preserved biatrial function, as demonstrated by two-dimensional STE and by 3-D echocardiographic measurements, supporting the hypothesis of a physiological remodelling of the heart. Although the presence

Conflict of interest disclosures

None.

Acknowledgments

The research was realized with a grant made available by the Italian Society of Cardiology, supported by a contribution of MSD Italy on behalf of MSD-ITALY MERCK SHARP & DOHME CORPORATION.

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