Date of Award

August 2022

Degree Type

Thesis

Degree Name

Master of Science

Department

Kinesiology

First Advisor

Kristian M O'Connor

Committee Members

Brooke A Slavens, Stephen C Cobb

Keywords

cheerleading, flip, landing, mechanics, surface, vertical

Abstract

Lateral ankle sprains are common injuries in cheerleading and typically occurring during tumbling. The landing surface can impact injury risk by modulating loading parameters and risky joint positions. Most surface-landing studies have used vertical landing tasks to study acrobatic populations, and few studies have compared vertical and flipping tasks. Therefore, the purpose of this study was to compare the effects of two cheerleading surfaces between vertical drop landing and flip landing tasks. Doing so explained surface characteristic influences on landing and the validity of using vertical landing tasks to represent acrobatic sports. Twelve collegiate cheerleaders (7 females, 5 males; age: 21.0 ± 2.5 years; mass: 64.5 ± 14.5 kg; height: 1.7 ± 0.1 m) performed flip (FLIP) and vertical (VERT) landing tasks over a harder (HARD) and matted (MAT) surface. Three-dimensional kinematics and kinetics were collected, and sagittal and frontal plane kinematic and kinetic variables were extracted during landing. Repeated measures ANOVAs (task x surface) were conducted to determine task and surface effects (p < .05). The FLIP task caused significantly greater impact peaks and loading rates, greater knee flexion at IC, peak knee extension and abduction moments, greater ankle plantar flexion and eversion moments, and less ankle plantar flexion at IC. There was greater vertical foot velocity at IC during FLIP tasks which was primarily due to angular velocity, and it likely explains the greater loading characteristics during FLIP tasks. The HARD surface landing caused significantly greater loading rates, greater knee flexion and ankle inversion at IC. Sagittal ankle moments had a significant task and surface interaction (p = .006), but no joint moment surface effects were observed. These indicated that FLIP and VERT tasks are significantly different due to angular components. The larger forces and joint stress observed in flipping places individuals at greater risk for ankle injuries. Flipping on a harder surface also introduced higher risks. The theory that landing on harder surfaces increases injury risk is supported. These results also caution individuals when generalizing vertical landings to acrobatic populations.

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