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Coordination variability (CV) is commonly analyzed to understand dynamical qualities of human locomotion. The purpose of this study was to develop guidelines for the number of trials required to inform the calculation of a stable mean lower limb CV during overground locomotion. Three-dimensional lower limb kinematics were captured for 10 recreational runners performing 20 trials each of preferred and fixed speed walking and running. Stance phase CV was calculated for 9 segment and joint couplings using a modified vector coding technique. The number of trials required to achieve a CV mean within 10% of 20 strides average was determined for each coupling and individual. The statistical outputs of mode (walking vs running) and speed (preferred vs fixed) were compared when informed by differing numbers of trials. A minimum of 11 trials were required for stable mean stance phase CV. With fewer than 11 trials, CV was underestimated and led to an oversight of significant differences between mode and speed. Future overground locomotion CV research in healthy populations using a vector coding approach should use 11 trials as a standard minimum. Researchers should be aware of the notable consequences of an insufficient number of trials for overall study findings.

Uphill training is applied to induce specific overload on the musculoskeletal system to improve sprinting mechanics. This study aimed to identify unique kinematic features of uphill sprinting at different slopes and to suggest practical implications based on comparisons we early stance phase. At take-off, steeper slopes induced significantly more extended joint angles and higher ROMs during the late stance phase. Compared with moderate slopes, more anti-phase coordination patterns were detected at steeper slopes. Thus, uphill sprinting at steeper slopes shares essential kinematic features with the early acceleration phase of level sprinting. Moderate inclinations induce biomechanical adaptations similar to those in the late acceleration phase of level sprinting. Hence, the specific transfer of uphill sprinting to acceleration depends on the slope inclinations.

Purpose To examine the influence of hip abductor strength, neuromuscular activation, and pelvis and femur morphology in contributing to sex differences in hip adduction during running. In addition, we sought to determine the best predictors of hip adduction during running for both men and women. Methods Fifteen female runners and 14 male runners underwent strength testing, instrumented overground running (e.g., kinematics and muscle activation), and computed tomography scanning of pelvis and femur. Morphologic measurements included bilateral hip width to femur length ratio, acetabulum abduction, acetabulum anteversion, femoral anteversion, and femoral neck-shaft angles. Sex differences for all variables were examined using independent t tests. Linear regression was used to assess the ability of each independent variable of interest to predict peak hip adduction during the late swing and stance phase of running. Results Compared with men, women exhibited significantly greater peak hip adduction during both late swing (8.5° ± 2.6° vs 6.2° ± 2.8°, P = 0.04) and stance phases of running (13.4° ± 4.2° vs 10.0° ± 3.2°, P = 0.02). In addition, women exhibited significantly lower hip abductor strength (1.8 ± 0.3 vs 2.0 ± 0.3 N·m·kg-1, P = 0.04), greater femoral neck-shaft angles (134.1° ± 5.0° vs 129.9° ± 4.1°, P = 0.01), and greater hip width to femur length ratios than men (0.44 ± 0.02 vs 0.42 ± 0.03, P = 0.03). Femoral anteversion was the only significant predictor of peak hip adduction during late swing (r = 0.36, P = 0.05) and stance (r = 0.41, P = 0.03). Conclusions Our findings highlight the contribution of femur morphology as opposed to hip abductor strength and activation in contributing to hip adduction during running.

Background: Lack of stability during stance negatively impacts gait and motor function for children with unilateral cerebral palsy. Improving stability and balance are the focus for gait rehabilitation). The One-Leg-Standing-Test may give valuable information about motor function and stability of stance for patients with unilateral cerebral palsy. Objective: This study aimed to investigate the relationship between the One-Leg-Standing-Test and the gross-motor-function-measurement and single-limb support time. Methods: The study included 18 patients with unilateral cerebral palsy (age 11.08 [SD 2.84] years old). The One-Leg-Standing-Test and pedobarographic evaluation were performed. Sections D and E of the gross-motor-function-measurement were assessed, and in pedobarographic evaluation, the single-limb support time (the total duration of mid-stance and terminal-stance during walking) was calculated to describe stability during stance. Results: For patients, the One-Leg-Standing-Test scores and single-limb support time values were lower on the affected side than on the unaffected side. The One-Leg-Standing-Test was correlated with single-limb support time (p = .02, r = 0.60) and section E (p < .01, r = 0.59) values. The One-Leg-Standing-Test was also correlated to total stance phase and section D. Conclusion: The One-Leg-Standing-Test gives valuable information about gross-motor-function but cannot be substituted for motor function tests. The single-limb support time value may be used to describe stability in stance during walking.

Background: Hip flexor muscles' tightness has been considered as one of the main risk factors for neuromuscular impairment of lower extremities not only lead to change the movement patterns but also probably result in changing the neuromuscular features of other muscles. The purpose of this research is study was to evaluate the iliopsoas tightness’ effect on electromyographic activity of hip extensor synergists during gait. Methods: In this case-control study fifteen 11-14 years old adolescents with iliopsoas tightness as experimental group, and 15 healthy adolescents which matched based on age, height, weight, body mass index, dominant leg and sport experience participated voluntarily as control group. Surface electromyographic activity of the gluteus maximus, adductor magnus and biceps femoris, were measured between groups during stance phase of gait. Results: Individuals with restricted hip flexor muscle length demonstrated more gluteus maximus activation during terminal stance (p=.001), more biceps femoris activation during mid stance (p=.002) and late stance (p=.001) and more adductor magnus activation during mid stance (p=.04) and late stance (p=.001). Conclusion: Adolescent soccer athletes with hip flexor muscle tightness exhibit more biceps femoris and adductor magnus and gluteus maximus activation during stance phase of gait. Thus, individuals with hip flexor muscle tightness appear to utilize different neuromuscular strategies to control lower extremity motion.

Background Falls among community-dwelling older adults are often triggered by uneven walkways. Joint coordination and its variability change with age and may place older adults at risk of falling. It is unclear how irregular surfaces impact lower-limb joint coordination and if such changes are exacerbated by aging. Research question To what extent do lower-limb inter-joint coordination and its variability, over flat and uneven brick walkways, differ between older and young healthy adults? Methods A motion-capture system collected kinematic data from walking trials on flat and uneven walkways in seventeen older (72.0 ± 4.2 years) and eighteen younger (27.0 ± 4.7 years) healthy adults. Continuous relative phase analyses were performed for the Knee-Hip and Ankle-Knee joint pairs. Mean Absolute Relative Phase (MARP) quantified coordination amplitude. Deviation Phase (DP) quantified coordinative variability. Two-way mixed ANOVA’s tested for effects of age, surface, and age × surface interactions. Results Uneven surfaces prompted more in-phase MARP inter-joint coordination in adults during most gait phases (p ≤ 0.024). Age × surface interactions were observed during initial contact (Ankle-Knee: p = 0.021, Knee-Hip: p = 0.001) and loading response (Knee-Hip: p = 0.017), with post-hoc analyses showing coordination accentuated in older adults. Uneven surfaces induced higher DP in Knee-Hip (p = 0.017) and Ankle-Knee joint coupling (p