Award Date

1-1-2006

Degree Type

Thesis

Degree Name

Master of Science (MS)

First Committee Member

John A. Mercer

Number of Pages

78

Abstract

The purpose of this study was to examine shock attenuation (SA) characteristics as well as stride characteristics before and after a fatigue protocol of the ankle dorsiflexors while running on a treadmill. Thirteen females (25.4 +/- 3.8 yrs; 63.2 +/- 8.9 kg; 164.3 +/- 3.1 cm) ran at the same (preferred) speed prior to and following bilateral local muscle fatigue of the ankle dorsiflexors. The fatigue protocol consisted of five sets of maximal concentric and eccentric contractions with a 15-second rest between the sets. Accelerometers (1004 Hz) were securely mounted on the distal aspect of the tibia and on the forehead. Head impact acceleration (ahead) and leg impact acceleration (a leg) over 10 consecutive strides per subject-condition were selected and used to quantify SA. Paired t-tests were used to compare each dependent variable (SA, ahead, aleg, stride frequency, stride length) between conditions (running before vs. after the fatigue protocol). Results indicated SA was 4.2% greater when running after the fatigue protocol [78.4 +/- 6.1 (mean +/- std)] than when running before the fatigue protocol (74.2 +/- 6.6 %; p <.05). Additionally, aleg was, on average, 1.7 g greater during running after (6.0 +/- 2.4 g) than before (4.3 +/- 1.6 g) the fatigue protocol (p <.05), a head exhibited no significant difference before and after the fatigue protocol. Furthermore, stride frequency was 1.4% greater when running after the fatigue protocol (p < .05). There was no statistical difference in stride length (p = .053). These results indicate that SA and aleg were sensitive to local muscle fatigue, with more shock being attenuated through body along with increased aleg during fatigued running. The increased aleg and SA suggest that local muscle fatigue contributes to the incapability of the musculoskeletal system to maintain the impact acceleration at the leg segment level; however, runners' systems may have adjusted to compensate for local fatigue. Therefore, the ankle dorsiflexors may play a role in the development of running related injuries.

Keywords

Attenuation; Characteristics; Effects; Fatigue; Local; Muscle; Running; Shock

Controlled Subject

Kinesiology; Physiology

File Format

pdf

File Size

1.57 MB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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