▼ Lower extremity injury is prevalent in individuals participating in sports. Numerous variables have been reported as predisposing factors; however, the predisposing effects of muscle fatigue on landing kinetics are unclear. The purpose of this study is to investigate the effects of a single session of repeated muscle fatigue on ground reaction forces (GRF) during drop landings. Ten female (22.5±0.85 yrs) and ten male (24.1±2.6 yrs), healthy recreational athletes performed five experimental conditions. The first condition consisted of five non-fatigue drop landings (60 cm), followed by four conditions of a fatigue protocol. Fatigue was induced by a 20 second Wingate Anaerobic Test. Following each fatigue condition, participants completed two drop landings (60 cm) onto a force platform with 5 minutes of active rest between each fatigue condition. Kinetic data were used to identify peak magnitude of force for forefoot force (F1), rearfoot force (F2), anterior/posterior (AP) and medial/lateral (ML) at both F1 and F2. A mixed effect factorial ANOVA with repeated measures for GRF variables was used to determine differences between gender and within fatigue. No significant main effect was observed between genders across all GRF variables. A significant main effect was observed within the non-fatigue and fatigue conditions in respect to peak F2 force, (0.003, p<.05, η2=0.634). The greatest significant difference was shown between the first fatigue drop landing condition (F2= 7.15±2.68 bodyweights) compared to the last fatigue drop landing condition (F2=9.38±2.1 bodyweights) in respect to peak F2, (0.002, p<.05). No significant difference was observed between gender and peak F2 (0.671, p<.05) and no difference was observed across AP and ML at peak F1 and F2 across conditions. A single session of repeated conditions of anaerobic muscle fatigue induced by WAT caused an initial reduction in peak F2 followed by an increase in peak F2 across conditions. Muscle fatigue consequently alters landing kinetics, potentially increasing the risk for injury. Advisors/Committee Members: Martin, Ralph.

▼ The purpose of this study was to explore student changes in conceptual development, epistemology, and motivations when evolution concepts are embedded and explicit reflective discourse is used in a unit for population ecology. The two research problems were: 1) What changes are observed in student's conceptual development, epistemology, and motivations when there is explicit reflective discourse within a population ecology unit with embedded evolution?, and 2) In what ways does explicit reflection influence students' mental models within a population ecology unit with embedded evolution? This mixed-method, quasi-experimental study assessed two regular high school biology classes in a small, urban, Midwestern high school. Students in this study had not studied evolution within any formal chapters, but had been immersed in a curriculum with embedded evolution. The study was conducted over a four-week period in a population ecology unit near the beginning of second semester. Instruction emphasized basic conceptions in population ecology. Five key intervention activities included evolutionary concepts as part of an embedded curriculum. The independent variable was explicit reflective discourse with one or two intervention questions after completion of these activities. Data included pre- and posttest surveys measuring (a) evolutionary understanding of natural selection, (b) science beliefs, and (c) science motivations. Written artifacts included (a) explanations to scenarios, (b) pre- and post-argument reflections revealing student's science beliefs and science motivations resultant from two argumentations, and (c) three, pre-, post-, and 6-week final concept maps constructed from 12 concepts. All data sources provided descriptive data. Conceptual change was interpreted from an ontological, epistemological, and motivational perspective. The experimental class receiving explicit reflective discourse showed greater overall increases in conceptual development. Students in both classes constructed teleological and proximate explanations. Overall, the experimental class gave greater numbers of evolutionary explanations. Scored propositions from concept maps showed a mixture of synthetic and scientific conceptions in both classes, however the experimental group showed greater scientific quality. Students in both classes exhibited direct-process ontology. Both classes had high degrees of epistemological and motivational commitments demonstrated by their engagement and subsequent improvements in conceptual development in both evolutionary and ecological conceptions. Advisors/Committee Members: Martin, Ralph.