Functional Characteristics of the Plantar Flexors in Ballet Dancer, Folk Dancer, and Non-Dancer Populations

Abstract

This study compared values representing strength, power, and endurance of the plantar flexors within a female population consisting of non-dancers, folk dancers and ballet dancers. Forty-five females were divided into three groups (15 non-dancers, 15 folk dancers, and 15 ballet dancers; mean age: 21 ± 2 years). Similarities and differences in functional characteristics of the plantar flexors within all three groups were tested on a Biodex isokinetic dynamometer. The trials consisted of: 1, isometric contractions at angles of 80°, 90°, and 100° of plantar flexion; 2, peak torque and power at six isokinetic angular velocities at 60°, 90°,120°,180°, 240°, and 300° per second; and 3, a fatigue test consisting of 30 maximal concentric contractions at 300° per second, where the amount of work produced and the percentage of decline in work produced was measured. The non-dancers achieved significantly lower isometric strength peak torque values (149 ± 69 Nm) than the folk dancers (187 ± 69 Nm) and ballet dancers (171 ± 69 Nm). The two dance groups were not significantly different. Isokinetic peak torque for the non-dancers was significantly lower (45 ± 2 Nm) than the folk dancers (57 ± 2 Nm) and the ballet dancers (56 ± 2 Nm). The two dance groups were not significantly different. The data showed no significant differences in isokinetic measurements of power or percentage of decline in work in the fatigability trials. However, the folk dancers and ballet dancers produced significantly more work than the non-dancers in the same fatigability trials. Based on the data, dancers as a general group are clearly a separate and distinct population from the normal, healthy, non-dancing females with regard to isometric strength, isokinetic strength, and the ability to produce work over a period of time.