The effects of six weeks of training on physical fitness and performance in teenage and mature top-level soccer players

The main aim of the present study was to investigate the effects of soccer-specific training on physical fitness components in adolescent elite soccer players and make comparisons with older counterparts. Twenty two male soccer players from the Serbian First Division team were allocated to two assigned trials according to age – young group (YG) and mature group (MG). Players in their teenage years (19 years and younger) were assigned to YG (10 subjects) and others to MG (12 subjects). Between the first and second test session, all subjects followed six weeks of soccer-specific periodized training programme. There were no differences between groups at pre- and post-training trial for body mass, vertical jump height, average anaerobic power and VO2max (P>0.05). Body fat was significantly lower in YG before and after training program as compared to MG (P<0.05). Body mass and fat dropped significantly in both groups after training program (P<0.05). Furthermore, average anaerobic power and VO2max along with vertical jump height, were significantly improved in both groups (P<0.05) at post-training performance. Finally, the magnitude of change in VO2max was significanty superior in MG as compared to YG after training program (18.3 vs. 7.8�20P<0.05). The findings of the present study indicate that the trainability indices are not highly influenced by age in top-level soccer players

Komparativna studija izmjerenog i procijenjenog vo2max u višestupanjskom funkcionalnom testu pripremljenosti nogometaša juniora

The multi-stage 20-m shuttle run test (MSRT) is one of the most popular field tests using equations based on test results or the final speed for an indirect estimation of maximal oxygen uptake (VO2max). The aim of this study was to compare the real VO2max value to the predicted value of VO2max by MSRT and rate the usefulness of the MSRT as a predictor of VO2max in young football players. Fifteen young football players, nominees for the 2004/2005 national Under-18 team, were included in this study. The subjects were 17.9±.2 years old, had an average height of 178.8±7 cm and an average weight of 71.8±7.5 kg. The players came from different Slovenian junior premier football league clubs and trained on average 4 to 5 times per week. Testing was conducted on all subjects over two days, between 9 a.m. and 2 p.m., on synthetic turf. A mobile device for the measurement of O2 and CO2 in expired air and ventilation during MSRT was used. On the basis of the test result (the number of levels and repetitions between them) VO2max was calculated. The correlation between the measured and predicted VO2max was determined with Pearson’s correlation coefficient. The comparison of both mean values showed that the measured value was significantly higher (p<.05), by as much as 8.5 ml O2 kg-1•min-1, than the MSRT-predicted VO2max. Variables were statistically correlated, but the correlation coefficient amounted to only .58. This study has shown that an indirect evaluation of aerobic capacity based on the multi-stage 20 m shuttle run test can lead to wrong conclusions in young soccer players. The correlation observed between the measured and predicted VO2max was too weak to predict the aerobic capacity of young football players with certainty.Višestupanjski test povratnog trčanja dionica od 20 metara (MSRT) je jedan od najpopularnijih terenskih testova koji koriste jednadžbe za procjenu maksimalnog primitka kisika (VO2max) na temelju ukupnog rezultata testa ili konačne brzine trčanja na kraju testa. Cilj ovog istraživanja bio je usporediti stvarne vrijednosti VO2max s procijenjenim vrijednostima VO2max dobivenima pomoću MSRT te ocijeniti korisnost toga terenskog višestupanjskog testa kao prediktora VO2max u mladih nogometaša. U istraživanje je bilo uključeno 15 mladih nogometaša izabranih za slovensku nacionalnu selekciju U18 u sezoni 2004./2005. Ispitanici su bili u dobi od 17,9±0,2 godina, prosječne visine 178,8±7 cm i prosječne težine 71,8±7,5 kg. Igrači su bili članovi različitih slovenskih prvoligaških juniorskih klubova i trenirali su u prosjeku 4 do 5 puta tjedno. Testiranje je provedeno na svim ispitanicima tijekom dva dana, u vremenu između 9 i 14 sati na umjetnoj travi. Korišteni su prijenosni uređaji za mjerenje O2 i CO2 u izdahnutomu zraku i ventilacije tijekom provedbe MSRT. Na temelju rezultata testa (razina otkaza i broj ponavljanja unutar razine otkaza) izračunat je VO2max. Povezanost između izmjerenoga i procijenjenoga VO2max utvrđena je Pearsonovim koeficijentom korelacije. Usporedba prosječnih vrijednosti pokazala je da je izmjerena vrijednost VO2max bila statistički značajno viša (p<0,05) za 8,5 ml O2 kg-1•min-1 od procijenjene vrijednosti VO2max koja je izračunata pomoću MSRT. Korelacija između varijabli bila je statistički značajna, ali je korelacijski koeficijent bio samo 0,58. Ovo je istraživanje pokazalo da neizravno vrednovanje aerobnoga kapaciteta rezultatima u testu MSRT može dovesti do pogrešnih zaključaka na populaciji mladih nogometaša. Utvrđena povezanost između izmjerene i procijenjene vrijednosti VO2max bila je preslaba da bi sa sigurnošću mogla poduprijeti procjenu aerobnoga kapaciteta u mladih nogometaša

Determination of Capacity and Rules of the Variability of Maximum Force Using Nonlinear Mathematical Models: a Case Study.

The aim of this study is to determine the capacity and the variability of maximum force rules measured 1 RM for eight muscle groups (back-hip extensors, legs extensors, arm extensors, back extensors, shoulder and arms extensors, shoulder joint flexors, hip and knee extensors, trunk flexors). The determination was performed on the experimental results of the top basketball center player using repeated measurements and nonlinear mathematical models methods. Changes in maximum force were induced with 8 months of weight lifting training and analised with nonlinear regression analysis within 95% confidence interval. The results indicate that from all the models applied only the Asymptotic Regression, Michaelis-Menten and Gompertz Growth models had satisfactory performance and provided solid solutions to the given problem. This means that the models developed in this study properly and reliably determine the capacity and predicted changes in the maximum force (1 RM) for all eight monitored muscle groups

Komparativna studija izmjerenog i procijenjenog vo2max u višestupanjskom funkcionalnom testu pripremljenosti nogometaša juniora

The multi-stage 20-m shuttle run test (MSRT) is one of the most popular field tests using equations based on test results or the final speed for an indirect estimation of maximal oxygen uptake (VO2max). The aim of this study was to compare the real VO2max value to the predicted value of VO2max by MSRT and rate the usefulness of the MSRT as a predictor of VO2max in young football players. Fifteen young football players, nominees for the 2004/2005 national Under-18 team, were included in this study. The subjects were 17.9±.2 years old, had an average height of 178.8±7 cm and an average weight of 71.8±7.5 kg. The players came from different Slovenian junior premier football league clubs and trained on average 4 to 5 times per week. Testing was conducted on all subjects over two days, between 9 a.m. and 2 p.m., on synthetic turf. A mobile device for the measurement of O2 and CO2 in expired air and ventilation during MSRT was used. On the basis of the test result (the number of levels and repetitions between them) VO2max was calculated. The correlation between the measured and predicted VO2max was determined with Pearson’s correlation coefficient. The comparison of both mean values showed that the measured value was significantly higher (p<.05), by as much as 8.5 ml O2 kg-1•min-1, than the MSRT-predicted VO2max. Variables were statistically correlated, but the correlation coefficient amounted to only .58. This study has shown that an indirect evaluation of aerobic capacity based on the multi-stage 20 m shuttle run test can lead to wrong conclusions in young soccer players. The correlation observed between the measured and predicted VO2max was too weak to predict the aerobic capacity of young football players with certainty.Višestupanjski test povratnog trčanja dionica od 20 metara (MSRT) je jedan od najpopularnijih terenskih testova koji koriste jednadžbe za procjenu maksimalnog primitka kisika (VO2max) na temelju ukupnog rezultata testa ili konačne brzine trčanja na kraju testa. Cilj ovog istraživanja bio je usporediti stvarne vrijednosti VO2max s procijenjenim vrijednostima VO2max dobivenima pomoću MSRT te ocijeniti korisnost toga terenskog višestupanjskog testa kao prediktora VO2max u mladih nogometaša. U istraživanje je bilo uključeno 15 mladih nogometaša izabranih za slovensku nacionalnu selekciju U18 u sezoni 2004./2005. Ispitanici su bili u dobi od 17,9±0,2 godina, prosječne visine 178,8±7 cm i prosječne težine 71,8±7,5 kg. Igrači su bili članovi različitih slovenskih prvoligaških juniorskih klubova i trenirali su u prosjeku 4 do 5 puta tjedno. Testiranje je provedeno na svim ispitanicima tijekom dva dana, u vremenu između 9 i 14 sati na umjetnoj travi. Korišteni su prijenosni uređaji za mjerenje O2 i CO2 u izdahnutomu zraku i ventilacije tijekom provedbe MSRT. Na temelju rezultata testa (razina otkaza i broj ponavljanja unutar razine otkaza) izračunat je VO2max. Povezanost između izmjerenoga i procijenjenoga VO2max utvrđena je Pearsonovim koeficijentom korelacije. Usporedba prosječnih vrijednosti pokazala je da je izmjerena vrijednost VO2max bila statistički značajno viša (p<0,05) za 8,5 ml O2 kg-1•min-1 od procijenjene vrijednosti VO2max koja je izračunata pomoću MSRT. Korelacija između varijabli bila je statistički značajna, ali je korelacijski koeficijent bio samo 0,58. Ovo je istraživanje pokazalo da neizravno vrednovanje aerobnoga kapaciteta rezultatima u testu MSRT može dovesti do pogrešnih zaključaka na populaciji mladih nogometaša. Utvrđena povezanost između izmjerene i procijenjene vrijednosti VO2max bila je preslaba da bi sa sigurnošću mogla poduprijeti procjenu aerobnoga kapaciteta u mladih nogometaša

The effects of a 4-week coffeeberry supplementation on antioxidant status, endurance, and anaerobic performance in college athletes

The main aim of this investigation was to evaluate the changes in total antioxidant capacity (TAC) and aerobic and anaerobic performance induced by supplementation of coffeeberry (CB) formulation for 4 weeks in college athletes. Twenty college athletes (14 males and 6 females) were allocated to two randomly assigned trials. Subjects in the CB group orally ingested capsules that contained CB formulation at a dose of 800 mg per day in two equal doses for 28 days, while subjects in the placebo (P) group ingested an equal number of identical-looking caps that contained cellulose. There were no changes in glucose, cholesterol, and lipoproteins within or between trials (p > 0.05). Total antioxidant capacity (TAC) was significantly higher in the CB versus P trial at the post- supplementation trial (1.66 ± 0.16 vs. 1.51 ± 0.05 mmol/L; p lt 0.05). There were no statistically significant changes in average anaerobic power, index of anaerobic fatigue, maximal heart rate, blood lactate, and maximal oxygen uptake within or between trials (p > 0.05). Heart rate recovery (HRR) index increased significantly in CB group as compared with baseline level (38 ± 4 vs. 32 ± 5 beats/min; p lt 0.05). Blood lactate after 10 min of recovery (Lactrec) significantly decreased in the CB group after supplementation protocol as compared with initial results (7.6 ± 4.2 vs. 5.5 ± 2.6 mmol/L; p lt 0.05). No subject reported any side effects from CB or P. The results of the present study indicate that supplementation with a CB formulation slightly increased antioxidant capacity, but there were minimal effects on recovery parameters after exercise in college athletes