A novel approach to the application of critical velocity within soccer

QP Physiology

Dunlop, Gordon ; Scobie, Nairn

University:University of Glasgow

Department:School of Life Sciences

关键词: QP Physiology;   

Others  :  http://theses.gla.ac.uk/4617/1/2013DunlopMSc.pdf

来源: University of Glasgow

【 摘 要 】

The relationship between velocity and time to exhaustion is hyperbolic and is defined by two parameters: critical velocity (CV), which represents the highest sustainable work rate; and the curvature constant (D’), which is the maximum amount of work that can be performed above CV. An important challenge that needs to be addressed however, before more research is conducted on both the importance of, and understanding of the physiology underlying CV and D’, is the protocol implemented for the measurement of these two parameters. At present, the number of exhaustive test bouts required restricts its use in intervention studies and makes its application within team based sports highly impractical. The main aim of the present study was to validate a novel critical velocity field test protocol that would allow the determination of CV in a single testing session. Twelve healthy male soccer players (mean ± SD) (22 ± 3yrs; 179 ± 7 cm; 74 ± 9 Kg; 4.5 ± 0.6 l.min¬-1) participated in this study and were randomly assigned to one of two intervention groups: a high intensity aerobic training group (INT) that completed two sessions per week comprising of 4x4 minute high intensity interval training at 90-95% of maximum heart rate (Hfmax); or alternatively, a controlled training group (CON), wherein habitual training practices were maintained throughout the 6 week training period.As outlined by the investigation testing protocol, both prior to, and following the completion of each respective 6-week intervention, all subjects performed an incremental exercise test for estimation of peak oxygen uptake (VO2peak) and peak treadmill running velocity (Vpeak) respectively. Having established Vpeak, a randomised series of four constant velocity treadmill tests to the limit of tolerance (tlim) were performed for the estimation of CV and D’. Each test was separated by a minimum period of 24 hours and was performed at designated work rates elected to span a tlim range of 3 to 20 minutes. Forming the novel element of this investigation, a field based test was also performed pre- and post-intervention. In contrast to the laboratory protocol however, 3 constant velocity tests to tlim were performed simultaneously, separated only by a 15minute recovery period for the determination of the V-t relationship and CV and D’ respectively.The results indicated that following the 6 week high intensity aerobic intervention, while a mean significant difference in peak oxygen uptake was displayed in the intervention group pre- to post-intervention (4.36 ± 0.67 vs. 4.50 ± 0.58 l.min-1; P = 0.020), this was not supported by a mean significant increase in critical velocity (3.65 ± 0.24 vs. 3.72 ± 0.25 m.sec-1; P = 0.355), post-intervention (lab determined CV values). No significant differences where displayed in either mean peak oxygen uptake (4.65 ± 0.45 vs. 4.56 ± 0.56 l.min-1; P = 0.225) or CV (3.66 ± 0.49 vs. 3.72 ± 0.52 m.sec-1; P = 0.216) (lab determined CV values) following the 6 week control intervention. While both protocol estimates for the determination of critical velocity displayed no significant difference pre- to post-intervention for either study group, (3.65 ± 0.24 vs. 3.72 ± 0.25 m.sec-1; P = 0.355) (INT lab) vs. (3.44 ± 0.10 vs. 3.44 ± 0.22 m.sec-1; P = 0.935) (INT field) and (3.66 ± 0.49 vs. 3.72 ± 0.52 m.sec-1; P = 0.216) (CON lab) vs. (3.42 ± 0.28 vs. 3.44 ± 0.32 m.sec-1; P = 0.640) (CON field) respectively, disparity between laboratory and field derived estimates was evident for both groups, with a significant difference between post-intervention protocol estimates being presented for CV within the INT group (3.72 ± 0.25 vs. 3.44 ± 0.22 m.sec-1; P = 0.018). Closer inspection of the data revealed little to no agreement between lab and novel field protocols estimates, with the field protocol inherently underestimating CV. Overall the lab protocol performed better than the field protocol, displaying a narrower interval (0.35m.sec¬-1) from which to detect a possible intervention effect relative to that of the field protocol (0.42m.sec-1). In concurrence it also provided better reproducibility for CV estimation, exhibiting a higher reproducibility coefficient relative to the field protocol (0.94 vs. 0.81) The key finding from the present study was that little evidence exists to validate the application of the novel field based protocol to determine critical velocity from a single testing session. The current results indicate that little to no agreement was found between laboratory derived and field test estimates of critical velocity, with the field test inherently underestimating critical velocity. Analysis of the results reveal that the novel field test, relative to the laboratory protocol, offers limited sensitivity and reproducibility to accurately estimate and track changes in critical velocity following a high intensity aerobic training intervention. The large disparity displayed between lab and field protocol estimates implies more research is required into the development of a novel field test that facilitates the accurate estimation of critical velocity from a single test sitting before its application within team based sporting environments can be justified.