Puberty, more important for cardiovascular adaptations than endurance training?

Cardiac adaptations in young triathletes: a 9-month longitudinal study during the peak height velocity period

PURPOSE

The present study examined the influence of endurance training on the morphological and functional heart adaptations in young athletes throughout a longitudinal 9-month follow-up period during the adolescent peak height velocity (PHV).

METHODS

Thirty-six 13- to 15-year-old males (twenty-three triathletes and thirteen untrained peers) were evaluated before and after a 9-month period during PHV. Maximal oxygen uptake (V ˙ O 2 max ) and power atV ˙ O 2 max were assessed during incremental cycling test. Resting echocardiography was performed to evaluate left ventricular (LV) morphology with standard parameters and using an original approach to assess LV shape. In addition, LV function was evaluated with advanced echocardiography tools including LV strains and myocardial work analyses from speckle-tracking echocardiography.

RESULTS

AbsoluteV ˙ O 2 max increased similarly in both groups but power atV ˙ O 2 max only significantly increased in triathletes (from 232 ± 46 to 264 ± 46 W, p < 0.001). Maturation had a significant effect on LV morphology with an enlargement in both groups. Endurance training induced additional adaptations in young triathletes, i.e., a cardiac remodeling characterized by an increase in LV length (from 7.5 ± 0.7 to 8.2 ± 0.6 cm, p < 0.01). The stroke volume was greater in young triathletes compared to untrained peers but with a constant difference throughout the 9-month period. Finally, speckle-tracking echocardiography and myocardial work remained unchanged during the follow-up and similar between groups.

CONCLUSION

Endurance training induced morphological adaptations during the PHV period without significant adaptation in LV function as evidenced by the absence of specific changes in LV strains and myocardial work.

A Prospective Study on Maximal Oxygen Uptake and Cardiovascular Functions in 12-Year-Old Endurance Athletes and Their Non-Endurance-Trained Peers

The maximal oxygen uptake (V̇O2max) is typically higher in endurance-trained adolescents than in non-endurance-trained peers. However, the specific mechanisms contributing to this remain unclear, as well as the impact of training during this developmental stage. This study aims to compare V̇O2max and cardiovascular functions between 12-year-old endurance athletes and non-endurance-trained over a 14-month period. Anthropometrics, V̇O2max, hemoglobin mass (Hbmass), blood volume (BV), and left-ventricular morphology were assessed four times over the 14 months in a group of young cross-country skiers (END, n = 42, age: 12.4 ± 0.5, girls: n = 27) and a group of controls (CON, n = 26, age: 12.3 ± 0.3, girls: n = 15). Throughout the 14-month follow-up, END did more weekly training than CON (7.0 ± 2.3 vs. 2.5 ± 2.4 h, p < 0.001), with only END conducting endurance training. END had ~18% higher V̇O2max relative to fat-free mass (FFM) than CON (p < 0.001). Stroke volume (SV) and left ventricular end-diastolic volume (LV EDV) relative to FFM were also higher for END than CON (p < 0.001 and 0.004), while no significant differences were found for Hbmass and BV. No significant interaction was seen for group and time for V̇O2max (p = 0.352-0.767) or any cardiovascular parameters (p = 0.131-0.956) in absolute measures or relative to FFM. In conclusion, the END group exhibited higher V̇O2max, LV EDV, and SV compared to the CON group, with no significant difference in BV and Hbmass. Despite substantial differences in training volume, the progression of these variables over the 14-month period was similar in both groups.

Young athlete's growing heart: sex differences in cardiac adaptation to exercise training during adolescence

BACKGROUND

Athlete's heart is a condition of exercise-induced cardiac remodelling. Adult male endurance athletes more often remodel beyond reference values. The impact of sex on remodelling through adolescence remains unclear. Paediatric reference values do not account for patient sex or exercise history. We aimed to study the effect of sex on cardiac remodelling throughout adolescence.

METHODS

We recruited 76 male (M) and female (F) 12-year-old cross-country skiers in a longitudinal cohort study. Echocardiography was performed and analysed according to guidelines at age 12 (48 M, 28 F), 15 (34 M, 14 F) and 18 (23 M, 11 F). Repeated echocardiographic measurements were analysed by linear mixed model regression.

RESULTS

Males displayed greater indexed left ventricular end-diastolic volumes (LV EDVi) from age 12 (M 81±7 vs F 76±7, mL/m², p≤0.01), and progressed further until follow-up at age 18 (M 2.3±9.7 vs F -3.9±4.5 ΔmL/m², p≤0.01). LV EDVi remained above adult upper reference values in both groups. Males increased LV Mass Index from age 12 to 18 (M 33±27 vs F 4±19, Δg/m², p≤0.01). Males displayed LV mass above paediatric reference values at ages 15 and 18. A subset of males (35%) and females (25%) displayed wall thickness above paediatric reference values at age 12. Cardiac function was normal. There was no sex difference in exercise hours.

CONCLUSION

Sex-related differences in athlete's heart were evident from age 12, and progressed throughout adolescence. Remodelling beyond reference values was more frequent than previously reported, particularly affecting males. Age, sex and exercise history may assist clinicians in distinguishing exercise-induced remodelling from pathology in adolescents.