Award Date

5-1-2013

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Kinesiology and Nutrition Sciences

First Committee Member

John Mercer

Second Committee Member

Dick Tandy

Third Committee Member

Janet Dufek

Fourth Committee Member

Carolee Dodge-Francis

Number of Pages

73

Abstract

This study intends to provide a basic biomechanical understanding of a specific movement within the sport of lacrosse, an overhand goal shot. Its purpose is to identify the different muscles of the lower extremity and the roles they perform during each phase of the lacrosse shot. Specifically, the study will compare how active muscles are between phases as well as between two different shot speeds. This research provides insight into the importance of timing muscle contractions that lead to a more accurate and faster shot.

Subjects (n=5 females, age: 21.8 ± 2 years, height: 162.56 ± 15.24cm, mass: 63.68 ± 23.6kg) were healthy and had at least one year of lacrosse experience. The lead leg was instrumented with electromyography (EMG) leads to measure muscle activity of the rectus femoris, biceps femoris, tibialis anterior, and the lateral and medial gastrocnemii. Subjects underwent testing for maximal voluntary isometric contraction (MVIC) for each muscle. The MVIC data was used to normalize all EMG activation amplitude data. Subjects were video recorded during five trials of a warm up speed shot (condition 1) and five trials of a game speed shot (condition 2).

Video analysis was used to identify the discrete events defining each phase and the times the events occurred. EMG data were processed by removing any zero offset, full-wave rectifying the data, and normalizing to MVIC. The times of each discrete event were used to extract electromyography data for analysis of each phase. Data were averaged per phase for each trial. Trial data were averaged per subject and subject data were averaged per condition per muscle.

Individual subject data was analyzed using a 4 (phase) x 2 (shot) ANOVA for each muscle. Statistical analyses were completed with SPSS software version 20.0. If an interaction was observed, paired t-tests were used to compare EMG between shots for each phase. Differences were noted using α=0.05 for all statistical tests.

The rectus femoris EMG was influenced by the interaction of phase and speed (p.05). EMG was significantly different between the phases, regardless of shot (p.05). There was no statistical difference between shots (p>.05) or phases (p>.05). The lateral gastrocnemius EMG was not influenced by the interaction of phase and speed (p>.05). There was no statistical difference between shots (p>.05) or phases (p>.05). The medial gastrocnemius EMG was not influenced by the interaction of phase and speed (p>.05). There was no statistical difference between phases (p>.05). EMG was different between shots, regardless of phases (p

Keywords

Biomechanics; EMG; Females; Human mechanics; Lacrosse; Leg – Muscles; Lower extremity; Muscles; Women

Disciplines

Biomechanics | Kinesiology

Language

English


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Biomechanics Commons

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