[How Valid is the Performance Diagnostic in Soccer?]. / Wie valide ist die Leistungsdiagnostik im Fußball?

BACKGROUND: Assessments of physical and physiological performance tests in soccer sports are still unspecific yet. There is also a lack of scientific validation using those as a "golden standard". Concerning match performance a large deficit also exist in sports and medical science. OBJECTIVE: The aim and purpose of this multicentric and prospective diagnostic study was to evaluate the validity of current established and recommended diagnostic tests for endurance and match performance (golden standard: real time of playing) in soccer. MATERIALS AND METHODS: In a prospective study protocol two German soccer teams from the fourth (n = 22) and third (n = 24) national league first underwent different tests of performance and diagnostics ahead of the competition season (tapping, drop jump, counter movement jump, speed dribbling, treadmill running test). Afterwards, match performance of each athlete was assessed by real time of playing (as a surrogate parameter) during the half season (14 and 25 matches). We finally compared test parameters with the match performance in a linear regression analysis. RESULTS: Our analysis showed no statistical relevant relationship between test parameters and match performance (r(2) < 0.10). Only the assessment in maximum of relative oxygen uptake during the treadmill test for endurance was associated with a higher amount of variance (12%). CONCLUSIONS: According to the study results there is no relevant and valid correlation between current established diagnostic tests in soccer sport and sport-specific performance. The time of real engagement during a match might be associated with a quality of performance for the single athlete. Therefore, the assessment of this match activity is the most important parameter for improving diagnostic tests in soccer. The existence of a "golden standard" is essential for validation of any tests and parameters and the development of new specific assessments. At the moment, physical performance tests have no scientific evidence in soccer sports.

Association of anthropometric qualities with vertical jump performance in elite male volleyball players.

AIM: The objective of this study was to examine the association between physical and anthropometric profiles and vertical jump performance in elite volleyball players. METHODS: Thirty-three elite male volleyball players (21±1 y, 76.9±5.2 kg, 186.5±5 cm) were studied. Several anthropometric measurements (body mass, stature, body mass index, lower limb length and sitting height) together with jumping height anaerobic power of counter movement jump with arm swing (CMJarm) were obtained from all subjects. Forward stepwise multiple linear regression analysis was performed to determine if any of the anthropometric parameters were predictive of CMJarm. RESULTS: Anaerobic power was significantly higher (P≤0.05) in the tallest players relative to their shorter counterparts. A significant relationship was observed between CMJarm and lower limb length (r2=0.69; P<0.001) and between the lower limb length and anaerobic power obtained with CMJarm (r2=0.57; P<0.01). While significantly correlated (P≤0.05) with CMJarm performance, stature, lower limb length/stature and sitting height/stature ratios were not significant (P>0.05) predictors of CMJarm performance. CONCLUSION: This study demonstrates that lower limb length is correlated with CMJarm in elite male volleyball players. The players with longer lower limbs have the better vertical jump performances and their anaerobic power is higher. These results could be of importance for trained athletes in sports relying on jumping performance, such as basketball, handball or volleyball. Thus, the measurement of anthropometric characteristics, such as stature and lower limb length may assist coaches in the early phases of talent identification in volleyball.