1,721,034 research outputs found
Preseason variations in aerobic fitness and performance in elite-standard soccer players: A team study
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Effects of Squat Flywheel Training on Strength, Muscle Structure and Performance.
No full textPurpose: Inertial flywheel device (YoYo Technology) is well known to induce strength adaptations and increase muscle mass after short term training. (Norrbrand 2011, Tesch 2004). Changes in muscle architectural parameters appropriate to improve peak torque has been described (Seynnes, 2007). However these adaptations were not directly related to specific performances like jump, velocity and change direction ability. Aim of the study is to evaluate quadriceps strength and architecture, lower limb fat free mass, and performance parameters after short term YoYo squat training.
Methods: 31 healthy young males has been randomly assigned at training (TR) or control (CON) group. TR underwent 16 training sessions in 9 weeks each consisting in 60 maximal reps at YoYo squat. Maximal Voluntary Contraction (MVC), Fat Free Mass (FFM), Fascicle length and thickness, Squat Jump (SJ) and Countermovement Jump (CMJ) Height and time on 30m dash and 20m shuttle have been measured pre and post training. Analysis of covariate has been done after log transformation.
Results: Compare to CON, TR showed higher MVC isometric (avg 25%, CI 95 13% to 38%), concentric (10%, 2%to 19%), eccentric (9%, 2% to 17%) extension (for each parameters, p<0,01). In TR, FFM (4%, 1% to 7%), fascicle length (8%, 1% to 16%), fascicle thickness (6%, 1% to 15%) increased compare to CON (p<0,01). SJ (9%, 2% to 16%), CMJ (8%, 1% to 14%), 20m shuttle(-4%, -7% to -1%) significantly improve (p<0,05) in TR compare to CON. 30m dash did not improve significantly compare to CON(-1%, -4% to2%, p=0,445), indicating that 20m shuttle performance is specially due by an augmented control of decreasing and increasing speed.
Conclusion: Augmented strength and changed muscle structure are in agreement with previous study. Longer fascicle is correlated with higher velocity of sarcomere contraction (Blazevich 2006). Outcomes show positive transfers in sport performance tasks, like jumping or braking and change sprinting direction. Flywheel device can be successfully used to improve performance in sport in which jumping or speed are key factors.
Blazevich A.J.,et al. J Anat 2006, 209:289–310
Norrbrand L, et al. Aviat Space and Environ Med 2011,82(1):13-9.
Seynnes OR, et al J. Appl Physiol 2007, 102(1):368-73.
Tesch PA, et al. Acta Physiol Scand 2004, 180(1):89-98
Validity of simple field tests as indicators of match-related physical performance in top-level professional soccer players
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Effect of match-related fatigue on short-passing ability in young soccer players.
No full textPURPOSE: To examine whether the fatigue accumulated during match play or determined by short bouts of high-intensity intermittent activities affect short-passing ability in junior soccer players. A further aim was to examine the influence of physical fitness as measured using the Yo-Yo Intermittent Recovery Test (YYIRT) on the changes in short-passing ability after a 5-min simulation of high-intensity activities (HIS). METHODS: Sixteen players (mean +/- SD: age 17.6 +/- 0.5 yr, height 174 +/- 7 cm, body mass 68 +/- 6 kg) participated in the study. A quasi-experimental control-period design was used for the study. Short-passing ability was measured using the Loughborough Soccer Passing Test (LSPT). Players completed the LSPT in two sessions during the 1-wk control period, followed by two unofficial matches during which the LSPT was performed during and after the first and the second halves of the game. Furthermore, the change in LSPT performance was determined after 5 min of HIS. RESULTS: A decline in LSPT performance was found during and after the game (P < 0.01). The accuracy of the LSPT decreased after the HIS. A significant correlation was found between the YYIRT scores and the decline in LSPT performance (accuracy, total time, total time with penalties) after HIS (r = -0.51 to -0.65; P < 0.05). CONCLUSIONS: This study showed that the fatigue developed during a match and after relatively short bouts of high-intensity intermittent activities has a detrimental effect on short-passing ability, and that the fatigue-related decline in technical proficiency for a given intensity is associated with the fitness level of the players
Testosterone and cortisol in 93 elite road cyclists during a 10-day stage race: relationship with final ranking
No full textCycling stage racing is a heavy and strenuous endurance event and it has been recognized that such exercise can affect the hormonal asset of hypothalamic–pituitary–adrenal (HPA) and hypothalamic–pituitary–testicular (HPT) axis. However, in cycling, literature on such changes is scarce and published data have been derived from small samples of athletes. The aims of study were to provide normative values for serum hormonal steroid values, changes in serum hormonal steroids and assess any relationships between a riders’ performance and their hormonal profile before and after the stage race. Male elite professional cyclists (n = 93) competing in the 2010 GiroBio 10-day stage race participated in this study. Blood chemistry measurements included cortisol (C), testosterone (T), free testosterone (fT) and sex hormone binding globulin (SHBG). Data are expressed as mean ± SD. Serum concentration of C and fT were lower at the end of GiroBio [C (nmol L−1): 559.34 ± 95.71 vs 469.59 ± 51.12; fT (pmol ml−1): 63.91 ± 27.85 vs 37.51 ± 17.86]. These serum hormonal (mean values ± 2SD) values may be near the physiological ceiling for elite cyclists. There was inverse correlation among average final speed and pre-competition serum concentration of T (r = −0.265, p = 0.01); average final speed was negatively correlated with riders body mass pre and post the 10-day stage event. In conclusion, pre-GiroBio serum C levels could be a useful benchmark to preserve riders’ health and, moreover, our data confirm that the strenuous effort sustained by riders during a stage race induces appreciable changes in the hormonal profile. In addition, our data suggest that lower levels of T could represent favourable prerequisite to cope better in a cycling stage race
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