Hormonal and metabolic substrate status in response to exercise in men of different phenotype.

OBJECTIVES: The present study verified the effect of moderate-to-high-intensity aerobic exercise on the endocrine response profile and adipose tissue in young healthy men with different phenotype characteristics. DESIGN: Eighteen men were divided into three experimental groups with defined body components and specific physical fitness: Endurance phenotype - EP (n = 6; low body mass; low fat content; aerobic endurance trained), Athletic phenotype - AP (n = 6; high body mass; low fat content, resistance trained), Obesity phenotype - OP (n = 6; high body mass; high fat content, untrained). METHODS: The participants performed an progressive exercise protocol on a treadmill (30% VO2max, 50% VO2max, 70% VO2max), separated by 45 s of passive rest for blood collection. RESULTS: Plasma glucose oxidation increased in relation to exercise intensity, but to a greater extent in the AP group. The free fatty acids' plasma level decreased with a rise in exercise intensity, but with different kinetics in particular phenotypes. Plasma growth hormone increased after the cessation of exercise and was significantly higher in all groups 45 min into recovery compared to resting values. Plasma insulin decreased during exercise in all groups, but in the OP, the decrease was blunted. CONCLUSIONS: The results indicate that the rate of lipolysis, hormonal and metabolic response to aerobic exercise depends on the individuals' phenotype. Thus, exercise type, duration and intensity have to be strictly individualized in relation to phenotype in order to reach optimal metabolic benefits.

Physiological, physical and on-ice performance criteria for selection of elite ice hockey teams.

The purpose of this study was to examine physiological and physical determinants of ice-hockey performance in order to assess their impact on the result during a selection for ice hockey. A total of 42 ice hockey players took part in the selection camp. At the end of the camp 20 best players were selected by team of expert coaches to the ice hockey team and created group G1, while the second group (G2) consisted of not selected players (non-successful group Evaluation of goodness of fit of the model to the data was based on the Hosmer Lemeshow test. Ice hockey players selected to the team were taller 181.95±4.02 cm, had lower% body fat 13.17±3.17%, a shorter time to peak power 2.47±0.35 s, higher relative peak power 21.34±2.41 W·kg(-1) and higher relative total work 305.18±28.41 J·kg(-1). The results of the aerobic capacity test showed significant differences only in case of two variables. Ice hockey players in the G1 had higher VO2max 4.07±0.31 l·min(-1) values than players in the G2 as well as ice hockey players in G1 showed a higher level of relative VO2max 51.75±2.99 ml·min(-1)·kg(-1) than athletes in G2. Ice hockey players selected to the team (G1) performed better in the 30 m Forwards Sprint 4.28±0.31 s; 6x9 Turns 12.19±0.75 s; 6x9 stops 12.79±0.49 s and Endurance test (6x30 m stops) 32.01±0.80 s than players in G2. The logistic regression model showed that the best predictors of success in the recruitment process of top level ice hockey players were time to peak power, relative peak power, VO2max and 30 m sprint forwards on ice. On the basis of the constructed predictive logistic regression model it will be possible to determine the probability of success of the athletes during following the selection processes to the team.

The blood antioxidant defence capacity during intermittent hypoxic training in elite swimmers.

The main objective of this study was to examine the chronic effect of simulated intermittent normobaric hypoxia on blood antioxidant defence capacity in swimmers. The study included 14 male and 14 female competitive swimmers performing part of land training under simulated intermittent normobaric hypoxia (O2 = 15.5%) or in normoxia. Land interval training took place twice per week, with a total of 8 training units during the study, performed with individualized intensity. The activities of blood antioxidant enzymes did not change significantly during the first and last training unit in the hypoxic and normoxic group. However, when comparing individual variables a significant effect of exercise was observed on GPx an CAT activities, whereas training units significantly differentiated GPx and GR activities. The oxygen conditions and gender had a significant influence on CAT activity. The total antioxidant capacity was not significantly affected. Only in male swimmers from the hypoxic group did the training significantly increase resting levels of MDA. In conclusion, training in normobaric hypoxia was not an adequate stimulus for the excessive response of the antioxidant defence system, despite increased oxidative stress in these conditions.

Regression shrinkage and neural models in predicting the results of 400-metres hurdles races.

This study presents the application of regression shrinkage and artificial neural networks in predicting the results of 400-metres hurdles races. The regression models predict the results for suggested training loads in the selected three-month training period. The material of the research was based on training data of 21 Polish hurdlers from the Polish National Athletics Team Association. The athletes were characterized by a high level of performance. To assess the predictive ability of the constructed models a method of leave-one-out cross-validation was used. The analysis showed that the method generating the smallest prediction error was the LASSO regression extended by quadratic terms. The optimal model generated the prediction error of 0.59 s. Otherwise the optimal set of input variables (by reducing 8 of the 27 predictors) was defined. The results obtained justify the use of regression shrinkage in predicting sports outcomes. The resulting model can be used as a tool to assist the coach in planning training loads in a selected training period.

Modelling analysis and prediction of women javelin throw results in the years 1946 - 2013.

The main goals of our study of the women's javelin throw were twofold:. first, to analyse the dynamics of female javelin throw results variability as a function of time (time period 1946-2014), second, to create a predictive model of the results during the upcoming 4 years. The study material consisted of databases covering the female track and field events obtained from the International Association of Athletics Federations. Prior to predicting the magnitude of results change dynamics in the time to follow, the adjustment of trend function to empirical data was tested using the coefficients of convergence. Phase II of the investigation consisted of the construction of predictive models. The greatest decreases in result indexes were noted in 2000 (9.4%), 2005-2006 (8.7%) and 2009 (7.4%). The trend increase was only noted in the years 2006-2008. In general, until 1998 the mean result improved by 54.6% (100% - results of 1946) whereas from 1999 through 2011 the result only increased by 1.3%. Based on data and results variability analysis it might be presumed that, in the nearest future (2015-2018), results variability will increase by approximately 9.7%. Percent improvement of javelin throw distance calculated on the basis of the 1999 raw input data is 1.4% (end of 2014).

The role of aerobic capacity in high-intensity intermittent efforts in ice-hockey.

The primary objective of this study was to determine a relationship between aerobic capacity ([Formula: see text]O2max) and fatigue from high-intensity skating in elite male hockey players. The subjects were twenty-four male members of the senior national ice hockey team of Poland who played the position of forward or defence. Each subject completed an on-ice Repeated-Skate Sprint test (RSS) consisting of 6 timed 89-m sprints, with 30 s of rest between subsequent efforts, and an incremental test on a cycle ergometer in the laboratory, the aim of which was to establish their maximal oxygen uptake ([Formula: see text]O2max). The analysis of variance showed that each next repetition in the 6x89 m test was significantly longer than the previous one (F5,138=53.33, p<0.001). An analysis of the fatigue index (FI) calculated from the times recorded for subsequent repetitions showed that the value of the FI increased with subsequent repetitions, reaching its maximum between repetitions 5 and 6 (3.10±1.16%). The total FI was 13.77±1.74%. The coefficient of correlation between [Formula: see text]O2max and the total FI for 6 sprints on the distance of 89 m (r =-0.584) was significant (p=0.003). The variance in the index of players' fatigue in the 6x89 m test accounted for 34% of the variance in [Formula: see text]O2max. The 6x89 m test proposed in this study offers a high test-retest correlation coefficient (r=0.78). Even though the test is criticized for being too exhaustive and thereby for producing highly variable results it still seems that it was well selected for repeated sprint ability testing in hockey players.