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Background Female collegiate cross-country (XC) runners have a high incidence of running-related injury (RRI). Limited reports are available that have examined potential intrinsic factors that may increase RRI risk in this population. Purpose To examine the relationships between RRI, hip muscle strength, and lower extremity running kinematics in female collegiate XC runners. Study Design Prospective observational cohort. Methods Participants included twenty female NCAA collegiate XC runners from Southern California universities who competed in the 2019-20 intercollegiate season. A pre-season questionnaire was used to gather demographic information. Hip muscle strength was measured with isokinetic dynamometry in a sidelying open-chain position and normalized by the runner's body weight (kg). Running kinematic variables were examined using Oualisys 3D Motion Capture and Visual 3D analysis. RRI occurrence was obtained via post-season questionnaires. Independent t-tests were used to determine mean differences between injured and non-injured runners for hip abductor muscle strength and selected running kinematics. Pearson correlation coefficients were calculated to examine relationships between hip muscle performance and kinematic variables. Results End-of-the-season RRI information was gathered from 19 of the 20 participants. During the 2019-20 XC season, 57.9% (11 of 19) of the runners sustained an RRI. There were no significant differences between mean hip abductor normalized muscle strength (p=0.76) or mean normalized hip muscle strength asymmetry (p=0.18) of injured and non-injured runners during the XC season. Similarly, no significant differences were found between mean values of selected kinematic variables of runners who did and who did not report an RRI. Moderate relationships were found between hip abductor strength variables and right knee adduction at footstrike (r=0.50), maximum right knee adduction during stance (r=0.55), left supination at footstrike (r=0.48), right peak pronation during stance (r=-0.47), left supination at footstrike (r=0.51), and right peak pronation during stance (r=-0.54) (all p≤0.05). Conclusions Hip abduction muscle strength, hip abduction strength asymmetry, and selected running kinematic variables were not associated with elevated risk of RRI in female collegiate XC runners. [ABSTRACT FROM AUTHOR]

Abstract Background Treadmill training with bodyweight support and manual assistance improves walking ability of patients with neurological injury. The purpose of this study was to determine how manual assistance changes muscle activation and kinematic patterns during treadmill training in individuals with incomplete spinal cord injury. Methods We tested six volunteers with incomplete spinal cord injury and six volunteers with intact nervous systems. Subjects with spinal cord injury walked on a treadmill at six speeds (0.18–1.07 m/s) with body weight support with and without manual assistance. Healthy subjects walked at the same speeds only with body weight support. We measured electromyographic (EMG) and kinematics in the lower extremities and calculated EMG root mean square (RMS) amplitudes and joint excursions. We performed cross-correlation analyses to compare EMG and kinematic profiles. Results Normalized muscle activation amplitudes and profiles in subjects with spinal cord injury were similar for stepping with and without manual assistance (ANOVA, p > 0.05). Muscle activation amplitudes increased with increasing speed (ANOVA, p < 0.05). When comparing spinal cord injury subject EMG data to control subject EMG data, neither the condition with manual assistance nor the condition without manual assistance showed a greater similarity to the control subject data, except for vastus lateralis. The shape and timing of EMG patterns in subjects with spinal cord injury became less similar to controls at faster speeds, especially when walking without manual assistance (ANOVA, p < 0.05). There were no consistent changes in kinematic profiles across spinal cord injury subjects when they were given manual assistance. Knee joint excursion was ~5 degrees greater with manual assistance during swing (ANOVA, p < 0.05). Hip and ankle joint excursions were both ~3 degrees lower with manual assistance during stance (ANOVA, p < 0.05). Conclusion Providing manual assistance does not lower EMG amplitudes or alter muscle activation profiles in relatively higher functioning spinal cord injury subjects. One advantage of manual assistance is that it allows spinal cord injury subjects to walk at faster speeds than they could without assistance. Concerns that manual assistance will promote passivity in subjects are unsupported by our findings.

Abstract Background Powered lower limb orthoses could reduce therapist labor during gait rehabilitation after neurological injury. However, it is not clear how patients respond to powered assistance during stepping. Patients might allow the orthoses to drive the movement pattern and reduce their muscle activation. The goal of this study was to test the effects of robotic assistance in subjects with incomplete spinal cord injury using pneumatically powered ankle-foot orthoses. Methods Five individuals with chronic incomplete spinal cord injury (ASIA C-D) participated in the study. Each subject was fitted with bilateral ankle-foot orthoses equipped with artificial pneumatic muscles to power ankle plantar flexion. Subjects walked on a treadmill with partial bodyweight support at four speeds (0.36, 0.54, 0.72 and 0.89 m/s) under three conditions: without wearing orthoses, wearing orthoses unpowered (passively), and wearing orthoses activated under pushbutton control by a physical therapist. Subjects also attempted a fourth condition wearing orthoses activated under pushbutton control by them. We measured joint angles, electromyography, and orthoses torque assistance. Results A therapist quickly learned to activate the artificial pneumatic muscles using the pushbuttons with the appropriate amplitude and timing. The powered orthoses provided ~50% of peak ankle torque. Ankle angle at stance push-off increased when subjects walked with powered orthoses versus when they walked with passive-orthoses (ANOVA, p < 0.05). Ankle muscle activation amplitudes were similar for powered and passive-orthoses conditions except for the soleus (~13% lower for powered condition; p < 0.05). Two of the five subjects were able to control the orthoses themselves using the pushbuttons. The other three subjects found it too difficult to coordinate pushbutton timing. Orthoses assistance and maximum ankle angle at push-off were smaller when the subject controlled the orthoses compared to when the therapist-controlled the orthoses (p < 0.05). Muscle activation amplitudes were similar between the two powered conditions except for tibialis anterior (~31% lower for therapist-controlled; p < 0.05). Conclusion Mechanical assistance from powered ankle-foot orthoses improved ankle push-off kinematics without substantially reducing muscle activation during walking in subjects with incomplete spinal cord injury. These results suggest that robotic plantar flexion assistance could be used during gait rehabilitation without promoting patient passivity.

With the aging process, falls and related injuries are common and unwanted events among older women. Lost balance is the last step before the frequent experience of falls. After menopause, women's bone conditions regarding health and balance performance steeply decline often resulting in serious injury. Our purpose in the study is to identify balance performance and its associations with soft tissue components among Korean-American (KA) women with three menopausal conditions. Researchers conducted a cross-sectional study with 63 KA women divided into three age groups: 25–35 years (young), 45–55 years old (middle), and 65+ years (old). Lean and fat mass on the entire body, appendicular and gynoid areas were measured by using the dual X-ray absorptiometry. Static and dynamic balance and physical performance (floor sit to stand) were tested. We found that with increased aging, lean mass, fat and body mass index were changed; balance and physical performance decreased significantly. In regression models, age and fat ratio of android/gynoid changes explain static balance and physical performance; appendicular lean mass predicted dynamic balance. With advancing age, maintaining lean mass and proportion of fat accumulation is critical for stable balance. [ABSTRACT FROM AUTHOR]

It is well established that remote whole-limb rhythmic movement (e.g., cycling or stepping) induces suppression of the Hoffman (H-) reflex evoked in stationary limbs. However, the dependence of reflex amplitude on the phase of the movement cycle (i.e., phase-dependence) has not been consistent across this previous research. The authors investigated the phase-dependence of flexor carpi radialis (FCR) H-reflex amplitudes during active walking and in kinematically matched static postures across the gait cycle. FCR H-reflexes were elicited in the stationary forearm with electrical stimulation to the median nerve. Significant phase-dependent modulation occurred during walking when the gait cycle was examined with adequate phase resolution. The suppression was greatest during midstance and midswing, suggesting increased ascending communication during these phases. There was no phase-dependent modulation in static standing postures and no correlation between lower limb background electromyography levels and H-reflex amplitude during active walking. This evidence, along with previous research demonstrating no phase modulation during passive walking, suggests that afferent feedback associated with joint position and leg muscle activation levels are not the sole source of the phase modulation seen during active walking. Possible sources of phase modulation include combinations of afferent feedback related to active movement or central motor commands or both. [ABSTRACT FROM PUBLISHER]

Background: Female collegiate cross-country (XC) runners have a high incidence of running-related injury (RRI). Limited reports are available that have examined potential intrinsic factors that may increase RRI risk in this population., Purpose: To examine the relationships between RRI, hip muscle strength, and lower extremity running kinematics in female collegiate XC runners., Study Design: Prospective observational cohort., Methods: Participants included twenty female NCAA collegiate XC runners from Southern California universities who competed in the 2019-20 intercollegiate season. A pre-season questionnaire was used to gather demographic information. Hip muscle strength was measured with isokinetic dynamometry in a sidelying open-chain position and normalized by the runner's body weight (kg). Running kinematic variables were examined using Qualisys 3D Motion Capture and Visual 3D analysis. RRI occurrence was obtained via post-season questionnaires. Independent t-tests were used to determine mean differences between injured and non-injured runners for hip abductor muscle strength and selected running kinematics. Pearson correlation coefficients were calculated to examine relationships between hip muscle performance and kinematic variables., Results: End-of-the-season RRI information was gathered from 19 of the 20 participants. During the 2019-20 XC season, 57.9% (11 of 19) of the runners sustained an RRI. There were no significant differences between mean hip abductor normalized muscle strength (p=0.76) or mean normalized hip muscle strength asymmetry (p=0.18) of injured and non-injured runners during the XC season. Similarly, no significant differences were found between mean values of selected kinematic variables of runners who did and who did not report an RRI. Moderate relationships were found between hip abductor strength variables and right knee adduction at footstrike (r=0.50), maximum right knee adduction during stance (r=0.55), left supination at footstrike (r=0.48), right peak pronation during stance (r=-0.47), left supination at footstrike (r=0.51), and right peak pronation during stance (r=-0.54) (all p≤0.05)., Conclusions: Hip abduction muscle strength, hip abduction strength asymmetry, and selected running kinematic variables were not associated with elevated risk of RRI in female collegiate XC runners., Competing Interests: The authors affirm that they have no financial affiliation (including research funding) or involvement with any commercial organization that has a direct financial interest in any matter included in this manuscript.

Clinicians and scientists often focus on tracking the recovery of motor skills after spinal cord injury (SCI), but less attention is paid to the recovery of sensory skills. Measures of sensory function are imperative for evaluating the efficacy of treatments and therapies. Proprioception is one sensory modality that provides information about static position and movement sense. Because of its critical contribution to motor control, proprioception should be measured during the course of recovery after neurological injury. Current clinical methods to test proprioception are limited to crude, manual tests of movement and position sense. The purpose of this study was to develop a quantitative assessment tool to measure joint position sense in the legs. We used the Lokomat, a robotic exoskeleton, and custom software to assess joint position sense in the hip and knee in 9 able-bodied (AB) subjects and 1 person with incomplete SCI. We used two different test paradigms. Both required the subject to move the leg to a target angle, but the presentation of the target was either a remembered or visual target angle. We found that AB subjects had more accurate position sense in the remembered task than in the visual task, and that they tended to have greater accuracy at the hip than at the knee. Position sense of the subject with SCI was comparable to those of the AB subjects. We show that using the Lokomat to assess joint position sense may be an effective clinical measurement tool., (© 2011 IEEE)