Evaluating side-to-side symmetry in the lower extremity has been significant in assessing injury risk and the success of rehabilitation programs. Considering limb dominance in the lower limbs is also important as limb dominance could influence symmetry measures. There is a need to assess symmetry, particularly in healthy populations, in tasks other than walking and running and establish how the dominant limb can impact symmetry. By evaluating symmetry in healthy adults, how the limbs function with respect to one another can be determined. Therefore, the first purpose of this study was to investigate the impact of lower limb dominance on walking and sitting-to-standing. Data was collected from 49 healthy older adults, aged 50-89 years old. Using loadsol® sensors (Novel, St. Paul, MN, USA), plantar loading data such as peak impact force and loading rate was calculated. Participants completed one sit-to-stand trial and three 10-meter walking trials, as these serve as prime examples of daily activities. The secondary purpose of this study was to assess the impact of lower limb dominance on athletic tasks like running and agility. The pedar-X® pressure insoles (Novel, St. Paul, MN, USA) were used to collect plantar loading data such as peak force, contact area, and contact time, from 10 athletes. Participants completed five t-drill trials and five agility ladder drill trials. The acceleration phase of the t-drill served as standard running. A mixed effects model was used to test if differences existed in various plantar loading outcome measures based on limb dominance. Non-parametric tests were used for non-normally distributed data. The statistical analysis determined that no significant differences existed between the dominant limb and non-dominant limb for the 10-meter walking trials peak impact force (p=0.245) or average loading rate (p=0.943). During the sit-to-stand trial, no significant differences existed in peak impact force (p=0.317) or average loading rate (p=0.943). For the agility ladder drill, the maximum force (p=0.427), contact area (p=0.517), or contact time (p=0.734) showed no significant differences. In the T-drill, the maximum force (p=0.385), contact area (p=0.571), or contact time (p=0.571) had no significant differences. These drive the conclusion that limb dominance does not need to be considered when assessing side-to-side symmetry. / Master of Science / Understanding how the left and right lower limbs of the body compare is important to preventing injuries and measuring if rehabilitation interventions are beneficial. A factor in that is knowing how the dominant limb can affect how the lower limbs compare to one another. Through symmetry, especially in healthy adults, a greater comprehension for over limb functionality can be better understood. There is need to assess the lower limb symmetry in healthy populations in tasks aside from walking and running as well as establish how the dominant limb is impacting that symmetry. The first purpose of this study was to observe how lower limb dominance affects walking and standing from a seated position. Data was collected from 49 healthy older adults, aged 50-89 years old. Insoles were placed in participants' shoes to collect plantar loading data. Each participant did two tasks: one trial of the sit-to-stand and three trials of 10-meter walking. The second purpose of this study was to observe how lower limb dominance affects athletic tasks such as running and agility. Loading insoles were used to collect data from 10 current or previous athletes. Each participant did five t-drill trials and five agility ladder trials. Statistical analyses established no significant differences were shown between the dominant and non-dominant limbs peak impact force for the 10-meter walking trials (p=0.245) nor for the average loading rate (p=0.943). For the sit-to-stand trial, no significant differences were seen in peak impact force (p=0.317) or average loading rate (p=0.943). In the agility ladder drill, no significant differences were shown for the maximum force (p=0.427), contact area (p=0.517), or contact time (p=0.734). In the agility ladder drill, no significant differences existed for the maximum force (p=0.385), contact area (p=0.571), or contact time (p=0.571). These findings suggested that the dominant limb does not impact lower limb comparisons.

PURPOSE: To examine gluteus medius strength and endurance in relation to lower limb stability, targeting and agility. METHODS: 57 participants performed isometric and dynamic gluteus medius strength and endurance tests of both lower limbs. Lower limb dominance was determined using the Waterloo Footedness Questionnaire-Revised (WFQ-R). Strength and endurance of gluteus medius were compared to single-leg performance of a stork stand, a lateral foot targeting task and a hopping test of agility. RESULTS: Body mass normalized isometric gluteus medius strength was found to be weakly and inversely correlated to agility score for both dominant limbs (r=-0.262, p=0.026) and non-dominant limbs (r=-0.335, p=0.006) with a lower agility score indicating better agility performance. For non-dominant limbs only, body mass normalized isometric gluteus medius strength correlated negatively to targeting speed (r=-0.229, p=0.045) and isometric gluteus medius endurance measured as percentage drop in strength over time correlated weakly and positively to the amount of body sway demonstrated during a single-leg stork stand task (r=0.253, p=0.030). CONCLUSION: Gluteus medius strength may be weakly related to improved agility performance while gluteus medius endurance may weakly relate to improved single-leg static balance performance. It is likely that other factors such as neuromuscular training have a much larger influence on stability, targeting ability and agility than the strength and endurance of the hip abductors alone.

Purpose: Young adolescent females are at the highest risk of sustaining an ACL injury, which may alter their movement and muscle activation patterns yet there is a lack sex- and age- specific guidelines for ACL injury management. The purpose of this study was to (1) evaluate the effects of limb dominance in a healthy uninjured population to serve as a baseline for the ACL-deficient cohort and (2) provide evidence of the neuromuscular patterns and biomechanical loading of uninjured and ACL-deficient knee joints in a female paediatric population. Methods: Eighteen active female adolescents with ACL rupture (ACLd) and 21 uninjured female adolescent controls matched for limb dominance (CON) participated in this study. Participants completed bilateral squats and drop vertical jumps (DVJ) while lower limb electromyography, kinetics and kinematics data were collected. Muscle synergies were extracted using a concatenated non-negative matrix factorization (CNMF) framework and compared between limbs, (CON dominant vs CON non-dominant and CON vs ACLd) across tasks and between limbs within tasks using intraclass correlation coefficients and statistical paramedic mapping. Results: ACLd participants took significantly longer to perform the squat relative to their uninjured peers. No significant differences were found for hip, knee and ankle peak joint flexion angles and moments between populations for the squat. Squat and DVJ muscle synergies were equivalent for dominant and non-dominant uninjured control limbs. ACL injured (ACL deficient and contralateral limbs) exhibited greater variability in DVJ synergy vectors than for the squat task. When comparing across tasks, scaling coefficients were consistently higher for the DVJ for all populations. Conclusion: Differences in lower limb kinematics, muscle activity and muscle activation patterns between dominant and non-dominant limbs indicate that limb symmetry, a clinical tool commonly used to assess rehabilitation and return to play may not provide relevant results. DVJ scaling factors were larger than those of the squat for all groups, likely due to the increased demand of that task. ACLd and CON participants completed squats and DVJ with similar lower limb joint angle patterns and muscle activity. ACL injured groups had fewer consistent vectors across tasks demonstrating greater variability in muscle activation patterns. This increased variability may be due to the ACL injury however, as injured participants were not studied pre- injury it cannot be confirmed.