Acute Effect of Neuromuscular Fatigue Following Joint Cooling on Postural Control and ‎Knee Kinematics During Drop-Landing Movement (with Injury Prevention Approach)‎

Lower limb injuries are more common in sports with plyometric movements that cause more neuromuscular fatigue. Among the treatments, cold therapy has many applications as an immediate treatment after injury during sport events. Because cooling the joint in a fatigue state may increase the risk of re-injury when returning to competition. Therefore, the purpose of this study was to investigate an acute effect of neuromuscular fatigue following local joint cooling on postural control and knee kinematics during drop-landing movement.

The present study was done using semi-experimental design. The study population of the present study were 40 female students of physical education field.  All had at least two years of their education and had been active in volleyball and basketball and had at least 3 sessions per week of sport activities and they had no injury in the lower extremities in the past six months. They were randomly divided into three experimental groups and one control group (10 people in each group). Measurements were performed at three times (pre-test, post-test 1 and post-test 2). The force plate (Bertec 40*60 USA) was used to measure center of pressure and the electrogoniameter (biometrics) to measure the range of knee motion during the drop landing, simultaneously. Cooling was performed for 20 minutes (for cooling and cooling after fatigue group) and fatigue protocol (fatigue and cooling after fatigue group) included repeated jumping in various directions from 20 cm platform. In the cooling after fatigue, the subjects first performed the fatigue protocol, then the knee joint cooling was applied immediately. All variables were measured before the interventions, immediately after them (first post-test) and 20 minutes after them (second post-test) in all groups. Analysis of variance with repeated measures and SPSS software in significant level α=0.05 was used for data analysis.

It has been shown that the mean of COPx changes increased during eccentric phase in all groups following 2nd post-test compared to 1st post-test(P=0/01). However, there was no significant difference between groups in the mean of COPx and COPy changes (p>0.05). Also, landing knee angle decreased in all groups in 1st post-test compared to pretest (p=0.04). There was no significant difference between groups in landing, takeoff and maximum knee angle (P>0.05).

Based on the results of the study, it seems that superficial cooling (using an ice pack) after neuromuscular fatigue similar to the conditions in sport events and competitions, has no significant effect on the biomechanical function of the lower extremities and balance of athletes. Therefore, local cooling of joint, as an immediate treatment method that has many benefits and positive physiological effects, to reduce the acute complications of injury, even despite the reduction of local joint temperature and in conditions where the athlete is tired, does not cause a serious risk for athletes during return to activity and there is no possibility of re-injury in them after cooling in a tired condition.