Ninety-eight young male soccer players were investigated for differences between elite players (E) and non-elite players (NE) in height, weight, BMI, skinfold, maturation, genetic potential for height, and birth weight and length. The subjects were included in the study at the age of 10-12 years and then examined three times with half-year intervals. Maturation was evaluated by testicular volumes. In addition, serum testosterone and insulin-like growth factor-I were measured. Adjustment for age was carried out because of a difference in age (11.9 [E] vs. 11.6 [NE] years) between the two groups. The players selected for the elite group were taller (152.7, 155.7, and 160 cm (E) vs. 147.4, 150.1, and 154.3 cm (NE), p = .015; MANOVA), had lower values for skinfolds (27.6, 28.3, and 27.5 mm (E) vs. 33.7, 35.1, and 36.1 mm (NE), p = .005), and greater testicular volume, compared with non-elite players (5.8, 7.6, and 9.3 ml (E) vs. 3.9, 5.0, and 6.6 ml (NE), p < .05). A tendency for higher values of serum testosterone in the elite group was present (p = .076), but no difference in IGF-I was found (p = .796). No differences in the genetic constitution for height was found. The present data shows that young soccer players selected for the best teams are taller, leaner, and more mature compared to young soccer players at a lower level.
Lone Hansen, Klaus Klausen, Jens Bangsbo and Jørn Müller
Jorn Trommelen, Milou Beelen, Marjan Mullers, Martin J. Gibala, Luc J.C. van Loon and Naomi M. Cermak
Carbohydrate mouth rinsing during exercise has been suggested to enhance performance of short (45–60 min) bouts of high-intensity (>75% VO2peak) exercise. Recent studies indicate that this performance enhancing effect may be dependent on the prandial state of the athlete. The purpose of this study was to define the impact of a carbohydrate mouth rinse on ~1-hr time trial performance in both the fasted and fed states. Using a double-blind, crossover design, 14 trained male cyclists (27 ± 6 years; 5.0 ± 0.5 W·kg−1) were selected to perform 4 time trials of ~1 hr (1,032 ± 127 kJ) on a cycle ergometer while rinsing their mouths with a 6.4% sucrose solution (SUC) or a noncaloric sweetened placebo (PLA) for 5 s at the start and at every 12.5% of their set amount of work completed. Two trials were performed in an overnight fasted state and two trials were performed 2 h after consuming a standardized breakfast. Performance time did not differ between any of the trials (fasted-PLA: 68.6 ± 7.2; fasted-SUC: 69.6 ± 7.5; fed-PLA: 67.6 ± 6.6; and fed-SUC: 69.0 ± 6.3 min; Prandial State × Mouth Rinse Solution p = .839; main effect prandial state p = .095; main effect mouth rinse solution p = .277). In line, mean power output and heart rate during exercise did not differ between trials. In conclusion, a sucrose mouth rinse does not improve ~1-hr time trial performance in well-trained cyclists when performed in either the fasted or the fed state.