A new measurement method: Measurement of active joint position sense under resistance within sport

Purpose: Active joint position sense (AJPS) measurements, which is without applying any external loads to muscles are usually made to assess post-injury recovery. When the injury is healed, other people return to their daily lives, while athletes return to intensive training and competitions. There are external forces acting on the muscles and joints within sports. This study had two purposes. The first one was to evaluate the impact of external load on AJPS, whereas the other one was to evaluate its relationship with jumping accuracy (JA). Two maximum force and four proprioception measurement sessions were made. Material and Method: 184 healthy students participated in the study. The maximum voluntary isometric contraction (MVIC) forces of the participants at 45-degree of knee angle were measured with an isokinetic dynamometer. The acuity of reaching the target of 50% MVIC for the force sense (FS) was assessed. was assessed by reaching to the target 50% MVIC. Two AJPS test were conducted without (AJPS1) and with load (AJPS2). 50% of MVIC was applied as a load in AJPS2. For JA, 50% of the maximum countermovement jump (CMJ) on the force plate was considered as the target jump height. In order to analyze obtained data set two way multiple analysis of variance, paired sample t test, and Pearson correlation coefficient was used. Results: AJPS was not affected by gender and activity level. AJPS2 error scores were statistically less than AJPS1 (p=0.035). While correlation between AJPS1 and 50% CMJ error scores was not significant, correlation between AJPS2 and 50% CMJ error scores was found statistically significant (p=0.013). Significant correlation was found between MVIC scores and FS error scores (p=0.000). Conclusions: According to these results, AJPS2 can be used in the evaluation of AJPS of healthy athletes and perhaps it may be more appropriate for the nature of the sport. Additionally, we can say that those with higher muscle strength have a worse sense of position. Considering these results, further research is needed to define the specific mechanism of proprioception. Key Words: External Load, Joint Position Sense, Vertical Jump, Muscle Strength, Force Sense