CMJ 2.1: TEST DI VALUTAZIONE FUNZIONALE DELL¿ARTO INFERIORE

Introduction: Although several methods have been proposed to assess bilateral asymmetry of the lower limbs (most of the tests require very expensive equipment), they do not reproduce the functionality of movements and are difficult to perform. Purpose: The aim of this study was to determine if the new functional test Countermovement Jump 2.1 (CMJ 2.1) was able to characterize the level of athletes and if it was able to determine functional deficits in injured athletes. Moreover, the purpose of this study was to analyze the reliability of CMJ 2.1 test and to compare it with other tests. Forty-nine subjects took part of this study (N=39 basketball players; N=10 soccer players). Methods: 3 different tests were used for this research: Hop & Stop Test, CMJ Test (both bipodalic and mopododalic jumps) and the proposed CMJ 2.1 Test consisting of countermovement jump with both legs and landing on one leg. Intraclass correlation coefficient was 0.92 (0.86–0.95) for CMJ 2.1 landing on right leg, and 0.94 (0.91–0.97) for CMJ 2.1 landing on left leg. The first three studies examined the difference between CMJ 2.1 Test and CMJ Test taking in consideration: (i) all subjects (N=49; age: 21.0±7.0 yr; height: 187.1±8.0 cm; weight: 80.3±9.9 kg), (ii) the difference between High Level group (N=26; age: 16.3±1.3 yr; height: 189.9±7.0 cm; weight: 81.0±9.8 kg) and Low Level group (N=23; age: 26.6±6.9 yr; height: 184.3±8.0 cm; weight: 79.5±10.2 kg); (iii) the difference between No Injured group (N=38; age: 20.2±7.3 yr; height: 187.3±7.8 cm; weight: 79.6±8.5 kg) and Injured group (N=11; age: 23.7±4.9 yr; height: 186.7±9.0 cm; weight: 82.4±13.9 kg) (major injuries happened at least 12 months before the study). Moreover, in according with other studies, bilateral asymmetry was calculated as [(stronger leg - weaker leg)/stronger leg] x 100. A positive sign indicates a stronger right leg; a negative sign indicates a stronger left leg. A (iv) fourth study examined the correlation between CMJ 2.1 and Hop & Stop Test, first considering all subjects then taking in consideration only Injured group. For this research, each subject did three trials of CMJ Test with both legs and six trials with one leg (three with right leg and three with left one), six trials of CMJ 2.1 Test (three times landing on right leg and three times landing on left leg) and one trial of Hop & Stop Test protocol. Results: First Study: During CMJ 2.1 subjects reached lower height than CMJ with both legs (p < 0.001). However, no significant differences were found between CMJ 2.1 landing on right leg and CMJ 2.1 landing on left leg. Second Study: Significant difference were found between High Level and Low Level group in CMJ with right leg (p < 0.001) and CMJ with left leg (p < 0.001), where High Level reached higher height than Low Level. No difference was found in CMJ with both legs. Moreover, the results obtained in the first study between CMJ 2.1 and CMJ with both legs were found in the second one. Third Study: Regarding the No Injured group, in CMJ 2.1 Test subjects reached lower height than CMJ with both legs (p < 0.001). However, no significant differences were found within CMJ 2.1 Test (landing on right and on left leg). The main results were found in Injured group: during CMJ 2.1 Test subjects reached lower height than CMJ with both legs (p < 0.001). Furthermore, significant differences were found between CMJ 2.1 with no injured leg and CMJ 2.1 with injured leg (p < 0.001), where injured leg reached lower height than no injured. The range of normal bilateral asymmetry (2.5th to 97.5th percentiles) was -6.6% to 6.2%. Fourth Study: Interesting correlations were found between CMJ 2.1 and Hop & Stop Test, however, the very large confidence limits make the correlation not acceptable. Probably, it would be useful to repeat this analysis by expanding the study sample. Conclusions: The functional test CMJ 2.1 is reliable and efficient to discriminate the injured leg from no injured. CMJ 2.1 is easy to execute, it does not need expensive equipment and respect the functionality of movement. For these reasons, it may be useful for coach, strength and conditioning coach and sports scientist to evaluate an injured athlete or athlete who is making a post-injury rehabilitation.