Masters Thesis

Physiological Profile of Monozygous Twins with Divergent Physical Activity Patterns

Variation in physiological characteristics and performance ability between individuals depends on environmental influence and genetics. By using monozygous twins with different exercise training backgrounds, we are able to control for genetics to better comprehend the impact of exercise on physiological features and performance variables. One pair of male monozygous twins participated in this study. The trained twin (TT) had a 35-year history of training and competing in endurance sports. The untrained twin (UT) had not participated in regular or structured physical training since high school (~35 years ago). Both participants underwent a battery of physical tests for body composition, bone density, flexibility, lung capacity, strength, power, endurance performance (VO2max), and anaerobic performance (Wingate). The greatest differences between participants were found for body composition, strength, and aerobic capacity. UT produced more peak torque (254 Nm vs. 137 Nm, 59.9% difference) and had greater grip strength (right hand=56.5 vs. 44.3kg, 24.2% difference; left hand=51.7 vs. 43.7kg, 16.8% difference). However, UT had a lower absolute (3.67 vs. 4.66 L/min, 23.9% difference) and relative (35.1 vs. 47.5 ml/kg/m, 30.1% difference) VO2max. UT also had a higher body fat percentage (BF%) (27.8% vs. 19.2%, 36.6% difference). In conclusion, long-term endurance training positively influenced VO2max and body composition, but was associated with lower isometric leg extensor and handgrip strength.


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