ABSTRACT
Responses of m. vastus lateralis to 8-week resistive training of various types at leg press mashine were investigated in 30 male subjects. Training loads were 25, 65 and 85% of one repetition maximum for low (LI), medium (MI), and high intensity (HI) training groups respectively, while angular velocities of contraction differed considerably between groups. The total work done during training session was identical. The maximum strengths during isokinetic knee extension in LI and HI groups were increased at most angular velocities. In group MI increments were obtained only during concentric contractions. Significant improvement of fatigue resistance and maximum oxygen consumption (V(O2max)) was seen only in group MI and LI, respectively. The training-related increase of cross-sectional area in type II fibers in m. vastus lateralis was in the order of HI > MI > LI group, and that of type I fibers was opposite. The increased myonuclear number was found for HI group. The data suggest that fiber hypertrophy, fatigue resistance and V(O2max) changes were related to the type of training.
Subject(s)
Muscle Fibers, Skeletal/physiology , Physical Endurance , Resistance Training , Adult , Electromyography , Humans , Knee/physiology , Knee Joint/physiology , Male , Oxygen Consumption/physiologyABSTRACT
The distribution of PPARG gene allele frequencies (Pro/Ala polymorphism) was studied in sportsmen specialized in speed and force athletics. A relationship between genotypes and human muscle transverse section area was evaluated. The PPARG Ala allele was significantly more incident in athletes than in controls, the incidence increasing with higher athletic qualification. A hypertrophic effect of PPARG Ala allele on muscle fibers was detected. Hence, the PPARG Pro12Ala polymorphism is associated with human motor activity.
Subject(s)
Motor Activity/genetics , PPAR gamma/genetics , Polymorphism, Genetic/genetics , Adolescent , Female , Gene Frequency/genetics , Humans , Immunohistochemistry , Male , Myosins/metabolism , Running , Skating , Sports , Swimming , Track and Field , Weight Lifting , Young AdultABSTRACT
Allele distribution of hypoxia-inducible factor gene (HIF1A; Pro582Ser polymorphism) was studied in power-oriented athletes and controls practicing no athletics; genotype relationships with muscle fiber composition were studied in speed skaters. Genotyping was carried out by PCR. The composition of muscle fibers was evaluated by the immunohistochemical analysis of m. vastus lateralis. The incidence of HIF1A Ser allele was significantly higher in weight-lifters than in controls (17.9 vs. 8.5%; p=0.001) and increased with athletic skill improvement. A relationship between HIF1A Ser allele and predominance of fast-twitch muscle fibers was shown (Pro/Ser 46.2 (13.8)%, Pro/Pro 31.4 (8.2)%; p=0.007). Hence, HIF1A Pro582Ser polymorphism is associated with muscle activity in humans.
