Effects of visual impairment on stroke parameters in Paralympic swimmers.

Abstract

To examine the relationship between degree of vision and stroking parameters in male and female Paralympic swimmers with visual impairment during the 50- and 100-m freestyle events. A video analysis was conducted at the 1996 Paralympic Games in which swimmers competed in three groups based on degree of impairment (S11, S12, and S13; S11 least amount of vision). A video camera placed 25 m from the start, perpendicular to the swimming direction, recorded the performance of each swimmer during the clean swim phase. Variables measured included total race time, clean swimming speed (CSS), stroke rate (SR), stroke length (SL), and stroke index (SI = CSS x SL). Comparisons of performance were made between the classes and between men and women. The men showed no significant differences between S12 and S13 on any of the variables or between all three classes on SL and SI. The S11 swimmers demonstrated a significantly slower total race time and CSS in both events. In the women, an increase in class was associated with a decrease in total race time, faster CSS, and increase in SI. In comparing men and women, men demonstrated a significantly faster CSS and total race time during both events, whereas no differences were observed in SR. Stroke parameters during the clean swim phase were affected by visual impairment in both men and women. The male classes, however, were not clearly distinct from each other based on the swimming variables measured, as no significant differences were found between S12 and S13 in either event. With the exception of stroke rate and length, performance of the women tended to increase with an increase in class.