The main purpose of this study was to examine the association between ACTN3 R577X polymorphism and the ability to produce peak power in young male athletes from various sports. Our hypothesis was that the ACTN3 R577X polymorphism is associated with jumping performance and athletes with RR genotype have better scores in tests than athletes with XX or RX genotype independently of the sport discipline. Two hundred young Polish male participants representing different disciplines were recruited for this study. Genotyping for ACTN3 gene was performed using polymerase chain reaction. The power output of lower extremities and the height of rise of the body mass center during vertical jumps were measured on a force plate. The genotype distribution of the ACTN3 gene did not differ significantly between groups of athletes. The significant difference in height of counter-movement jump was found between athletes with RR and XX genotype (0.446±0.049m vs. 0.421±0.036m, respectively, P=0.026). The ACTN3 RR genotype was associated with greater muscle power and height of jump in young male athletes. These results suggest that the ACTN3 gene may play a significant role in determining muscle phenotypes. However, this gene is only one of many factors which could contribute to athletes' performance and muscle phenotypes.

Somatotype Variables Related to Muscle Torque and Power in Judoists: The purpose of this study was to examine the relationship between somatotype, muscle torque and power output in judoists. Thirteen judoists (age 18.4±3.1 years, body height 178.6±8.2 cm, body mass 82.3±15.9 kg) volunteered to participate in this study. Somatotype was determined using the Heath-Carter method. Maximal muscle torques of elbow, shoulder, knee, hip and trunk flexors as well as extensors were measured under static conditions. Power outputs were measured in 5 maximal cycle ergometer exercise bouts, 10 s each, at increasing external loads equal to 2.5, 5.0, 7.5, 10.0 and 12.5% of body weight. The Pearson's correlation coefficients were calculated between all parameters. The mean somatotype of judoists was: 3.5-5.9-1.8 (values for endomorphy, mesomorphy and ectomorphy, respectively). The values (mean±SD) of sum of muscle torque of ten muscle groups (TOTAL) was 3702.2±862.9 N × m. The power output ranged from 393.2±79.4 to 1077.2±275.4 W. The values of sum of muscle torque of right and left upper extremities (SUE), sum of muscle torque of right and left lower extremities (SLE), sum of muscle torque of the trunk (ST) and TOTAL were significantly correlated with the mesomorphic component (0.68, 0.80, 0.71 and 0.78, respectively). The ectomorphic component correlated significantly with values of SUE, SLE, ST and TOTAL (-0.69, -0.81, -0.71 and -0.79, respectively). Power output was also strongly correlated with both mesomorphy (positively) and ectomorphy (negatively). The results indicated that the values of mesomorphic and ectomorphic somatotype components influence muscle torque and power output, thus body build could be an important factor affecting results in judo.

Anthropometry and neuromuscular fitness have been shown to relate with taekwondo (TKD) performance; however, little information is available on the variation of these fitness components by sex and age in athletes practicing this sport. The aim of the present study was to examine the anthropometry and neuromuscular fitness of TKD athletes by sex and age. A total of 393 athletes (7–48 years old), separated into six age groups (7–9, 10–11, 12–13, 14–17, 18–32, and 33+), were examined for anthropometry and performed a series of neuromuscular fitness tests (flexibility, agility, muscle power, and isometric strength). An age × sex interaction on body mass, body height, and body fat percentage (BF, p≤0.003, η²≥0.045), but not on body mass index (p=0.172, η²=0.020), was shown, where a larger increase in body mass and body height from 12–13 to 14–17 groups was observed in males than in females, and the sex difference in BF increased from 12–13 to 14–17 age group. An age × sex interaction on sit-and-reach (SAR) test, mean power output in the Bosco test, and Abalakov jump (p≤0.038, η²≥0.031) was observed with larger differences between 12–13 and 18–32 groups in males than in females. In SAR, it was remarkable that the male athletes achieved similar scores as female athletes in the 18–32 group. An age × sex group interaction on measures of isometric muscle strength (right and left handgrip, trunk, and legs) was also shown (p≤0.002, η²≥0.068), where larger differences in male than female athletes were observed between the 12–13 and 14–17 groups. From a practical perspective, coaches can use these findings as reference for the evaluation of their athletes. Because the anthropometric characteristics and neuromuscular fitness varied by sex (i.e., highest scores in males, except flexibility) and age (i.e., highest scores in the 18–32 age group) with unique sport-specific patterns in TKD athletes, these findings would be important for the development of specific training programs.

The aim of the study was to determine changes in the magnitude and direction of secular trends in body height, body weight, body mass index (BMI) and fat percentage in university students from a university of technology and a university of physical education in a period of 50 years. The data were derived from the examinations of male students from the Warsaw University of Technology, conducted four times, in 1959, 1971, 1994, 2011, and male students from the Józef Piłsudski University of Physical Education in Warsaw, who were examined in 1963, 1972, 1996, and 2012. Body height, body weight and thickness of 2 skinfolds (triceps skinfold and abdomen skinfold) were measured. Body mass index (BMI) and fat percentage (FAT%) were also calculated. Current university students are taller and heavier than their peers from the previous decades, with BMI remaining within the reference range. A substantial increase in fat percentage was found in both groups. Over the period of fifty years, mean fat percentage in students from the university of technology increased by 6.3% (F1,3 = 116.56, p < 0.001, η² = 0.3736), whereas this increase in the students from the university of physical education rose by 3.5% (F1,3 = 72.94, p < 0.001, η² = 0.3181). Changes in secular trends in the students from both universities are likely to be linked to the dynamic economic and systematic transformation in Poland observed in the period of the last 50 years. The period of economic transformations in the last decade was more conducive to physical development of university students than the previous period of economic crises.