Longitudinal changes in maximal oxygen uptake in adolescent girls and boys with different training backgrounds.

The purpose of this study was to investigate the effects of high-volume endurance training on the development of maximal oxygen uptake (VO2max ) in physically active boys and girls between the ages of 12 and 15 years, using a longitudinal design. The children participated in organized training in sports clubs for an average of 7-10 hours per week, with one group undertaking a high volume of endurance training (~7 hours per week; End boys, n = 23 and End girls, n = 17) and the other group having a primary focus on technical and tactical skill development, undertaking low volumes of endurance training (~1.6 hours per week; non-End boys, n = 29 and non-End girls, n = 9). VO2max and anthropometrics were assessed at age 12, 13, and 15. At age 12, VO2max was 58.9 (5.6), 65.5 (7.2), 56.5 (6.5), and 58.8 (7.9) mL·kg-1 ·min-1 in End girls, End boys, non-End girls, and non-End boys, respectively. Over the three years, there was no difference between the training groups in the development of VO2max independent of scaling. In boys, VO2max relative to body mass (BM) did not change from age 12 to 15, while VO2max tended to decrease relative to fat-free mass (FFM). In girls, VO2max relative to BM decreased slightly from age 12 to 15, with no changes over the years relative to FFM. The present longitudinal study suggests that in growing active children during puberty, high volumes of systematic endurance training do not have an additional effect on VO2max compared with similar volume of training mainly aiming at developing motor skills.

From talented child to elite athlete: The development of cardiac morphology and function in a cohort of endurance athletes from age 12 to 18.

BACKGROUND: Adult athletes undergo cardiac adaptions in what is known as the "athlete's heart". Cardiac adaptations in young athletes have not been described in longitudinal studies but have previously been believed to be uniform in nature. METHODS: Seventy-six cross-country skiers were assessed at age 12. Forty-eight (63%) completed the first follow-up at age 15 and 36 (47%) the second follow-up at age 18. Comprehensive exercise data were collected. Echocardiography with three-dimensional measurements and cardiopulmonary exercise testing were performed at all time points. The cohort was divided into active and former endurance athletes, with an eight hours of weekly endurance exercise cut-off at age 18. RESULTS: The athletes underwent eccentric remodelling between ages 12 and 15, and concentric remodelling between ages 15 and 18. At age 18, the active endurance athletes had greater increases in inter-ventricular wall thickness (1.8 ± 1.4 Δmm vs 0.6 ± 1.0 Δmm, p < 0.05), left ventricular (LV) posterior wall thickness (1.6 ± 1.2 Δmm vs 0.8 ± 0.8 Δmm, p < 0.05), LV mass (63 ± 30 Δg vs 27 ± 21 Δg, p < 0.01), right ventricular (RV) end-diastolic area (3.4 ± 4.0 Δcm2 vs 0.6 ± 3.5Δ cm2, p < 0.05), RV end-systolic area (1.0 ± 2.3 Δcm2 vs -0.9 ± 2.0 Δcm2, p < 0.05) and left atrial volume (24 ± 21 ΔmL vs 6±10 ΔmL, p < 0.05) and had greater indexed maximal oxygen uptake (66.3 ± 7.4 mL/min/kg vs 57.1 ± 8.2 mL/min/kg, p < 0.01). There was no significant difference for LV volumes. CONCLUSION: This study finds a shift in the development of the young athlete's heart. Between ages 12 and 15, the active endurance athletes underwent eccentric remodelling. This dynamic switched to concentric remodelling between ages 15 and 18.

The developing athlete's heart: a cohort study in young athletes transitioning through adolescence.

BACKGROUND: Athlete's heart is a term used to describe physiological changes in the hearts of athletes, but its early development has not been described in longitudinal studies. This study aims to improve our understanding of the effects of endurance training on the developing heart. METHODS: Cardiac morphology and function in 48 cross-country skiers were assessed at age 12 years (12.1 ± 0.2 years) and then again at age 15 years (15.3 ± 0.3 years). Echocardiography was performed in all subjects including two-dimensional speckle-tracking strain echocardiography and three-dimensional echocardiography. All participants underwent cardiopulmonary exercise testing at both ages 12 and 15 years to assess maximal oxygen uptake and exercise capacity. RESULTS: Thirty-one (65%) were still active endurance athletes at age 15 years and 17 (35%) were not. The active endurance athletes had greater indexed maximal oxygen uptake (62 ± 8 vs. 57 ± 6 mL/kg/min, P < 0.05) at follow-up. There were no differences in cardiac morphology at baseline. At follow-up the active endurance athletes had greater three-dimensional indexed left ventricular end-diastolic (84 ± 11 mL/m2 vs. 79 ± 10 mL/m2, P < 0.05) and end-systolic volumes (36 ± 6 mL/m2 vs. 32 ± 3 mL/m2, P < 0.05). Relative wall thickness fell in the active endurance athletes, but not in those who had quit (-0.05 ΔmL/m2 vs. 0.00 mL/m2, P = 0.01). Four active endurance athletes had relative wall thickness above the upper reference values at baseline; all had normalised at follow-up. CONCLUSION: After an initial concentric remodelling in the pre-adolescent athletes, those who continued their endurance training developed eccentric changes with chamber dilatation and little change in wall thickness. Those who ceased endurance training maintained a comparable wall thickness, but did not develop chamber dilatation.

Morphological changes and myocardial function assessed by traditional and novel echocardiographic methods in preadolescent athlete's heart.

Background Athlete's heart is a term used to describe the morphological and functional changes in the hearts of athletes. Recent studies suggest that these changes may occur even in preadolescent athletes. This study aims to improve our understanding of the changes occurring in the preadolescent athlete's heart. Design and methods Cardiac morphology and function in 76 preadolescent cross-country skiers (aged 12.1 ± 0.2 years) were compared with 25 age-matched non-competing preadolescents. Echocardiography was performed in all subjects, including 2D speckle-tracking strain echocardiography and 3D echocardiography. All participants underwent cardiopulmonary exercise testing to assess oxygen uptake and exercise capacity. Results Athletes had greater indexed VO2 max (62 ± 7 vs. 44 ± 5 mL/kg per min, p < 0.001), indexed left ventricular end-diastolic volume (79 ± 7 vs. 68 ± 7 mL/m2, p < 0.001), left ventricular mass (69 ± 12 vs. 57 ± 13 g/m2, p < 0.001), indexed right ventricular basal diameter (28.3 ± 3.0 vs. 25.4 ± 3.5 mm/m2, p < 0.001) and right atrial area (10.6 ± 1.4 vs. 9.7 ± 1.2 cm2/m2, p < 0.01). There was no difference in left ventricular ejection fraction, global longitudinal strain, and global circumferential strain and right ventricular fractional area change between the groups. Controls had higher right ventricular global longitudinal strain (-28.1 ± 3.5 vs. -31.1 ± 3.3%, p < 0.01). VO2 max was highly correlated to left ventricular end-diastolic volume ( r = 0.76, p < 0.001). Conclusion Athletes had greater left ventricular mass and greater left and right ventricular chamber dimensions compared with controls, while left ventricular function did not differ. Interestingly, right ventricular deformation was significantly lower compared with controls. This supports the notion that there is physiological, adaptive remodelling in preadolescent athlete's heart.

Maximal aerobic capacity in the winter-Olympics endurance disciplines: Olympic-medal benchmarks for the time period 1990-2013.

PURPOSE: To generate updated Olympic-medal benchmarks for VO2max in winter endurance disciplines, examine possible differences in VO2max between medalists and nonmedalists, and calculate gender difference in V˙ O2max based on a homogeneous subset of world-leading endurance athletes. METHODS: The authors identified 111 athletes who participated in winter Olympic Games/World Championships in the period 1990 to 2013. All identified athletes tested VO2max at the Norwegian Olympic Training Center within ±1 y of their championship performance. Testing procedures were consistent throughout the entire period. RESULTS: For medal-winning athletes, the following relative VO2max values (mean:95% confidence intervals) for men/women were observed (mL · min-1 · kg-1): 84:87-81/72:77-68 for cross-country distance skiing, 78:81-75/68:73-64 for cross-country sprint skiing, 81:84-78/67:73-61 for biathlon, and 77:80-75 for Nordic combined (men only). Similar benchmarks for absolute VO2max (L/min) in male/female athletes are 6.4:6.1-6.7/4.3:4.1-4.5 for cross-country distance skiers, 6.3:5.8-6.8/4.0:3.7-4.3 for cross-country sprint skiers, 6.2:5.7-6.4/4.0:3.7-4.3 for biathletes, and 5.3:5.0-5.5 for Nordic combined (men only). The difference in relative VO2max between medalists and nonmedalists was large for Nordic combined, moderate for cross-country distance and biathlon, and small/trivial for the other disciplines. Corresponding differences in absolute VO2max were small/trivial for all disciplines. Male cross-country medalists achieve 15% higher relative VO2max than corresponding women. CONCLUSIONS: This study provides updated benchmark VO2max values for Olympic-medal-level performance in winter endurance disciplines and can serve as a guideline of the requirements for future elite athletes.

Not quite so fast: effect of training at 90% sprint speed on maximal and repeated-sprint ability in soccer players.

Abstract The aim of the present study was to investigate the effect of training at an intensity eliciting 90% of maximal sprinting speed on maximal and repeated-sprint performance in soccer. It was hypothesised that sprint training at 90% of maximal velocity would improve soccer-related sprinting. Twenty-two junior club-level male and female soccer players (age 17 ± 1 year, body mass 64 ± 8 kg, body height 174 ± 8 cm) completed an intervention study where the training group (TG) replaced one of their weekly soccer training sessions with a repeated-sprint training session performed at 90% of maximal sprint speed, while the control group (CG) completed regular soccer training according to their teams' original training plans. Countermovement jump, 12 × 20-m repeated-sprint, VO2max and the Yo-Yo Intermittent Recovery Level 1 test were performed prior to and after a 9-week intervention period. No significant between-group differences were observed for any of the performance indices and effect magnitudes were trivial or small. Before rejecting the hypothesis, we recommend that future studies should perform intervention programmes with either stronger stimulus or at other times during the season where total training load is reduced.

VO2max characteristics of elite female soccer players, 1989-2007.

PURPOSE: To quantify VO2max among female competitive soccer players as a function of performance level, field position, and age. In addition, the evolution of VO2max among world-class players over an 18-y period was quantified. METHODS: Female players (N = 199, 22 ± 4 y, 63 ± 6 kg, height 169 ± 6 cm), including an Olympic winning squad, were tested for VO2max at the Norwegian Olympic Training Center between 1989 and 2007. RESULTS: National-team players had 5% higher VO2max than 1st-division players (P = .042, d = 0.4), 13% higher than 2nd-division players (P < .001, d = 1.2), and 9% higher than junior players (P = .005, d = 1.0). Midfielders had 8% higher VO2max than goalkeepers (P = .048, d = 1.1). No significant differences were observed across outfield players or different age categories. There was a trend toward lower relative VO2max across time epochs. CONCLUSIONS: This study demonstrated that VO2max varies across playing-standard level in women's soccer. No significant differences in VO2max were observed across outfield positions and age categories. Over time, there has been a slight negative development in VO2max among elite Norwegian soccer players.

Maximal aerobic power characteristics of male professional soccer players, 1989-2012.

PURPOSE: The purpose of this investigation was to quantify maximal aerobic power (VO2max) in soccer as a function of performance level, position, age, and time of season. In addition, the authors examined the evolution of VO2max among professional players over a 23-y period. METHODS: 1545 male soccer players (22 ± 4 y, 76 ± 8 kg, 181 ± 6 cm) were tested for VO2max at the Norwegian Olympic Training Center between 1989 and 2012. RESULTS: No differences in VO2max were observed among national-team players, 1st- and 2nd-division players, and juniors. Midfielders had higher VO2max than defenders, forwards, and goalkeepers (P < .05). Players <18 y of age had ~3% higher VO2max than 23- to 26-y-old players (P = .016). The players had 1.6% and 2.1% lower VO2max during off-season than preseason (P = .046) and in season (P = .021), respectively. Relative to body mass, VO2max among the professional players in this study has not improved over time. Professional players tested during 2006-2012 actually had 3.2% lower VO2max than those tested from 2000 to 2006 (P = .001). CONCLUSIONS: This study provides effect-magnitude estimates for the influence of performance level, player position, age, and season time on VO2max in men's elite soccer. The findings from a robust data set indicate that VO2max values ~62-64 mL · kg-1 · min-1 fulfill the demands for aerobic capacity in men's professional soccer and that VO2max is not a clearly distinguishing variable separating players of different standards.