The effect of training in male prepubertal and pubertal monozygotic twins

Abstract

Nine male pairs of monozygotic twins aged 11-14 years, height 147 (7.6) cm and body mass 39.7 (9.6) kg, participated in this study. Twin zygocity was tested using morphological, dermatoglyphic and hematologic methods, and Tanner's five stages were used for the evaluation of biological maturation. One twin from each pair undertook training for 6 months, three times a week, with running at 85-120% of the lactate anaerobic threshold (LT). Anthropometrics, determination of maximum O(2) uptake (.VO(2max)), LT and maximal blood lactate concentration ([La](max)) was carried out before, during and after training. No significant difference existed between the trained twins and their untrained brothers before training. After training, the trained twins increased their .VO(2max), (per kg body mass) by 10.6% and their LT by 18.2% (P<0.01), reaching values that differed significantly from those of their untrained brothers [57.5 (3.6) ml.kg(-1).min(-1) vs 55.4 (3.3) ml.kg(-1).min(-1) and 13.4 (1.1) km.h(-1) vs 12.7 (1.1) km.h(-1), respectively]. In addition, in the trained twins relative body fat was reduced (P<0.05) from 17.8 to 16.2% and their somatotype altered significantly (decrease of endomorphy and mesomorphy and increase of ectomorphy), while in the untrained twins there was no change in these parameters. Both groups of twins significantly increased their absolute .VO(2max) after the 6 months of training, the trained by 14,9% [from 2.08 (0.43) to 2.37 (0.45) l.min(-1)] and the untrained by 10.5% [from 2.10 (0.41) to 2.32 (0.47) l.min(-1)], but no difference was registered between them. A comparison of the intrapair changes in .VO(2max) of prepubertal and pubertal twins showed an influence of training in the prepubertal (19.3% vs 5.2%) but not in the pubertal twins (12.7% vs 13.1%). Using analysis of variance, the relative importance of training, heredity and their interaction was evaluated to be 20%, 70% and 10%, respectively, for the change in body fat, 35%, 45% and 20%, respectively, for the change in relative .VO(2max) and 25-30%, 50-60% and 15-20%, respectively, for the change in LT. In conclusion, training during pubertal growth can favour aerobic power (depending on body composition) as well as aerobic capacity, but it has no effect on absolute .VO(2max). Genetic control seems to have a strong effect on the extent of adaptations, and the genotype-training interaction explains a small, but prominent part of them.

The Beneficial Effects of Physical Activity: Is It Down to Your Genes? A Systematic Review and Meta-Analysis of Twin and Family Studies

“…First, there were an insufficient number of family studies deriving results from independent samples. Second, although we were able to obtain heritability estimates from three twin studies, these estimates were uninformative since the 95% CI covered the whole range (0,1) (apart from Danis and colleagues who estimated heritability without utilizing DZ twins in its design [27]), and differences between the r MZ and r DZ were not statistically significant (Table 1). Instead, we were able to pool the r MZ for selected outcomes, giving us quantitative estimates of the upper bound of heritability.…”

“…There were 11 studies (nine twin studies [20, 27–30, 32–35] and two family studies [24, 36]) which investigated body composition measures and their response following a PA intervention. Pooling of eight twin studies results (excluding Danis and colleagues [27] due to different methodology) suggest there is a significant r MZ across the majority of body composition measures (Table 4).…”

Aerobic fitness and its relationship to sport, exercise training and habitual physical activity during youth

“…The running speed corresponding to a blood lactate accumulation of 4 mM has been observed to increase following training 72 73. Intervention studies have reported high intensity74 75 but not low intensity58 76 training to result in a decrease in blood lactate accumulation during subsequent submaximal exercise.…”

Fitness and body composition profiling of elite junior South African rugby players

“…15 This finding may be a result of maturation, where VO2 continues to increase through the age of 18, 13 combined with genetic limitations governing oxygen consumption. 5 Training may also influence VO2max, contributing to approximately 35% of the variance of the increase. These measures of aerobic capacity are higher than those reported in junior and amateur rugby league players from Australia 11,12 but lower than those values reported in other national team players.…”