Abstract

The study compares the sway variables registered by means of the EquiTest dynamic posturography system prior to and after maximal exercise in athletes of different specializations in order to identify, which of static and dynamic conditions of the Sensory Organisation Test (SOT) and Head Shake SOT (HS SOT) is the most sensitive in detecting post-exercise changes of postural stability. A group of 20 athletes (age 23.2 ± 1.3 years, height 175.8 ± 7,3 cm, weight 70.6 ± 8.6 kg) underwent in random order in different days tests of static and dynamic balance prior to and after maximal exercise on the cycle ergometer. Pre-exercise protocol was comprised of standard SOT and HS SOT conditions based on the EquiTest system. In the SOT, during the first three conditions with eyes open, eyes closed, and sway-referenced. During the HS SOT subjects performed motions of the head in roll and pitch planes while their eyes were closed and support surface was either fixed or sway-referenced. After exercise only selected conditions were repeated, two static with subject’s eyes open and eyes closed, and two dynamic with their eyes closed and sway-referenced vision. Results showed that in static conditions, there were no significant differences in the equilibrium score after exercise in comparison with pre-exercise level neither with eyes open (95.75 ± 0.80 and 90.44 ± 3.97 %, respectively) nor eyes closed (93.06 ± 1.79 and 87.00 ± 4.19 %, respectively). On the other hand, its values in dynamic conditions were significantly (p < 0.01) lower as with eyes closed (78.11 ± 4.10 and 54.56 ± 14.63 %, respectively) as with sway-referenced vision (81.54 ± 4.57 and 56.50 ± 13.91 %, respectively). However, in some athletes, the equilibrium score not even in the most difficult condition 5 did not differ significantly after exercise. This may be documented by its higher values in three 20 seconds phases of recovery (68.20 ± 5.59, 77.60 ± 8.44 %, and 76.20 ± 7.76 % respectively) as compared to rest of the group (39.40 ± 14.50, 59.00 ± 14.09, and 63.80 ± 11.69 %, respectively). By adding roll and pitch head motions while support surface was sway-referenced and subject’s eyes closed its values significantly (p < 0.01) decreased from 60.00 ± 7.78 to 30.00 ± 13.10, 47.00 ± 8.30, and 54.60 ± 9.00 %, respectively. Similar trend was evident for strategy score. Its decreased values in conditions of sway-referenced support surface with subject’s eyes closed from 81.37 ± 5.53 to 59.11 ± 17.19 % as well as with sway-referenced vision from 85.17 ± 4.27 to 70.67 ± 7.76 % reflect tendency to use both, ankle and hip strategy in maintenance of postural stability. Sensory analysis revealed that vestibular ratio significantly (p < 0.01) decreased after exercise (82 and 60 %, respectively), whereas any changes in somatosensory one were observed (97 and 96 %, respectively), indicating that vestibular is more affected by exercise that somatosensory system. However, reduced post-exercise measurements of postural stability under conditions 3 and 4, does not allow calculating neither visual nor its preference ratio. Results indicate that for most athletes’ condition 5 of the SOT, during which support surface is sway-referenced and subject’s eyes are closed is sensitive enough for the ervaluation of exercise effect on postural stability. However, in order to reveal slight changes induced by exercise in highly skilled athletes’, additional head movements in the roll and pitch planes have to be performed. It may be therefore concluded that such a dynamic condition may be considered as the most sensitive for the assessment of post-exercise postural stability in elite athletes. Verf.-Referat