Endurance Training in Young Female Athletes:

Electrical and structural adaptations of the paediatric athlete’s heart: a systematic review with meta-analysis

Aim

To describe the electrocardiographic (ECG) and echocardiographic manifestations of the paediatric athlete’s heart, and examine the impact of age, race and sex on cardiac remodelling responses to competitive sport.

Design

Systematic review with meta-analysis.

Data sources

Six electronic databases were searched to May 2016: MEDLINE, PubMed, EMBASE, Web of Science, CINAHL and SPORTDiscus.

Inclusion criteria

(1) Male and/or female competitive athletes, (2) participants aged 6–18 years, (3) original research article published in English language.

Results

Data from 14 278 athletes and 1668 non-athletes were included for qualitative (43 articles) and quantitative synthesis (40 articles). Paediatric athletes demonstrated a greater prevalence of training-related and training-unrelated ECG changes than non-athletes. Athletes ≥14 years were 15.8 times more likely to have inferolateral T-wave inversion than athletes <14 years. Paediatric black athletes had significantly more training-related and training-unrelated ECG changes than Caucasian athletes. Age was a positive predictor of left ventricular (LV) internal diameter during diastole, interventricular septum thickness during diastole, relative wall thickness and LV mass. When age was accounted for, these parameters remained significantly larger in athletes than non-athletes. Paediatric black athletes presented larger posterior wall thickness during diastole (PWTd) than Caucasian athletes. Paediatric male athletes also presented larger PWTd than females.

Conclusions

The paediatric athlete’s heart undergoes significant remodelling both before and during ‘maturational years’. Paediatric athletes have a greater prevalence of training related and training-unrelated ECG changes than non-athletes, with age, race and sex mediating factors on cardiac electrical and LV structural remodelling.

Influence of training and maturity status on the cardiopulmonary responses to ramp incremental cycle and upper body exercise in girls

It has been suggested that the potential for training to alter the physiological responses to exercise in children is related to a “maturational threshold”. To address this, we investigated the interaction of swim-training status and maturity on cardiovascular and metabolic responses to lower and upper body exercise. Twenty-one prepubertal [Pre: 11 trained (T), 10 untrained (UT)], 30 pubertal (Pub: 14 T, 16 UT), and 18 postpubertal (Post: 8 T, 10 UT) girls completed ramp incremental exercise on a cycle and an upper body ergometer. In addition to pulmonary gas exchange measurements, stroke volume and cardiac output were estimated by thoracic bioelectrical impedance, and muscle oxygenation status was assessed using near-infrared spectroscopy. All T girls had a higher peak O2 uptake during cycle (Pre: T 49 ± 5 vs. UT 40 ± 4; Pub: T 46 ± 5 vs. UT 36 ± 4; Post: T 48 ± 5 vs. UT 39 ± 8 ml·kg−1·min−1; all P < 0.05) and upper body exercise (Pre: T 37 ± 6 vs. UT 32 ± 5; Pub: T 36 ± 5 vs. UT 28 ± 5; Post: T 39 ± 3 vs. UT 28 ± 7 ml·kg−1·min−1; all P < 0.05). T girls also had a higher peak cardiac output during both modalities, and this reached significance in Pub (cycle: T 21 ± 3 vs. UT 18 ± 3; upper body: T 20 ± 4 vs. UT 15 ± 4 l/min; all P < 0.05) and Post girls (cycle: T 21 ± 4 vs. UT 17 ± 2; upper body: T 22 ± 3 vs. UT 18 ± 2 l/min; all P < 0.05). None of the measured pulmonary, cardiovascular, or metabolic parameters interacted with maturity, and the magnitude of the difference between T and UT girls was similar, irrespective of maturity stage. These results challenge the notion that differences in training status in young people are only evident once a maturational threshold has been exceeded.