The search of non-invasive and easy-to-monitor variables is essential to improve the athlete performance. The assessment of neuromuscular characteristics, such as velocity, with a lineal position transducer (LPT), allows training optimization and just like heart rate variability (HRV) guaranties an adequate athlete monitoring. The autonomic nervous system (ANS) and Sympathetic nervous system (SNS) exert an important influence on skeletal muscle functions. However, there are no studies that correlate the activity of SNS with current technologies such as LPT to calculate several neuromuscular performance variables. Otherwise, the results of HRV assessment could be related to a TLP strength test performance. PURPOSE: The aim of this study is to find correlations between HRV variables and TLC variables during a half squat movement in young female soccer players. METHODS: Thirteen professional female soccer players were tested (Age 20.7 years +/-2.62, Weight 60.9 kg +/- 4.4), we analyzed HRV during standing, we also evaluated the velocity of a half squat movement with a LPT, during a maximal strength test, statistical analyses were performed to determine associations. RESULTS: Associations were found between Stress index during standing position and Mean acceleration to Maximal velocity (m/s/s) (R2 0,3115 P 0,0381), Mean velocity (R2 0,3284 P 0,0322), Propulsive mean velocity (R2 0,3189 P 0,0354). CONCLUSIONS: Stress Index (SI) is a variable that reflects sympathetic activation and suggest autonomic reactivity to stress situations indicating an adequate response to confront the demands presented by the sport. Thus, an abnormal sympathetic predominance could result in chronic fatigue which would evince a SI higher elevation, giving the index greater value. According to our findings the SI during standing position correlated with velocity and acceleration variables during half squat, this suggests that adequate sympathetic reactivity could contribute to the improvement of neuromuscular variables. We hypothesized that SI could be a simple non-invasive way to measure sympathetic reactivity in sports, being part in assessment and monitoring of performance. We also suggest that interventions aimed to improve sympathetic reactivity could improve neuromuscular performance.