Abstract

Generalized joint laxity (GJL), a condition in which most joints of the body move beyond the accepted normal range of motion, is present in many ballet and modern dancers. It has been associated with an increased risk of injury, decreased muscle strength, and greater landing forces. Increased joint laxity results in joint instability and may precede the development of osteoarthritis, which is associated with a reduction in cartilage thickness. We hypothesized that dancers with GJL would have decreased hip cartilage thickness, as well as greater hip adduction angles and greater ground reaction force on landings. Twenty female ballet and modern dancers (mean age: 21.0 ± 1.79 years; mean weight: 57.0 ± 5.71 kg; mean years of dance experience: 14.6 ± 3.53 years; mean hours of training per week: 19.2 ± 7.24 hours) were recruited from college and local dance programs and screened for GJL. Each dancer performed three forward drop landings onto a force plate and received an MRI on their dominant hip. There was a significant difference in hip cartilage thickness, as viewed in the frontal plane (GJL group average: 2.66 ± 0.33 mm; control group average: 3.14 ± 0.48 mm; p = 0.0160), between the groups. There were no significant differences in peak hip adduction angle on landing (GJL group average: 80.9 ± 5.04 degrees; control group average: 77.9 ± 5.78 degrees; p = 0.2269) or peak landing ground reaction force (GJL group average: 5.56 ± 1.28 body weights; control group average: 5.17 ± 0.82 body weights; p = 0.4274) between the generalized joint laxity group and the control group. Dancers with GJL have thinner cartilage at the hip. These results suggest that dancers with GJL may be at a greater risk for injury. Therefore, these dancers may benefit from strength training programs, rather than flexibility training, to help counteract the joint instability that can lead to injury.

Degree

MS

College and Department

Life Sciences; Exercise Sciences

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

2017-07-01

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd9400

Keywords

generalized joint laxity, MRI, dancers, hip cartilage thickness

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