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Background: Bounce rope-skip holds immense scope as an aerobic exercise in space and time constrained urban setting with additional constraints placed by pandemic situations such as Covid 19, wherein adherence to commonly performed weight-bearing, aerobic activities like walking and running is a challenge. Limited knowledge informing biomechanical demands and misconceptions about knee joint loading, confines safe application of bounce rope-skip in health promotion. Thus, present study aimed to explore kinematics and lower-extremity joint loading during rope-skipping compared to walking and running., Methods: Following ethical approval, 3D motion analysis of bounce rope-skip, walk and run was captured from 22 healthy female participants aged 18-25yr using 12-camera Vicon system and 2AMTI force plates. Three trials for bounce rope-skip were recorded with five skip-jumps on force-plates at a cadence of 105 skips/min. Mid-skip, mid-gait and mid-run data were averaged to compute kinetic and kinematic variables for hip, knee and ankle during loading/initial contact, take-off/push-off and flight/mid-swing phases of rope-skip, walk and run., Result: Average time of one rope-skip cycle was 1.2sec; mean foot contact time was 0.55sec and flight time was 0.65sec. In one bounce rope-skip cycle, hip motion ranged between 13.4 o -35.3 o flexion; knee between 13.6 o -67.9° flexion and ankle between 34.5 o dorsiflexion to-13.4 0 plantarflexion. Vertical ground reaction force (vGRF) during rope-skip (landing-phase) was lower compared to run; however, it was higher than walk (p < 0.001). In coronal plane, peak hip and knee adductor moment during rope-skip were lower compared to run and higher than walk (p < 0.001)., Conclusion: Bounce rope-skip generated low lower extremity joint loading compared to run; supporting its prescription as a hip and knee joint-protective aerobic weight-bearing exercise for health promotion in young adults., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Optimal management and surgical planning of severe bony deformities and muscle tendon unit contractures demands comprehensive evaluation of all structures including the dynamic muscle tendon length of all muscles around the joint during gait. Objectives: Present study aimed to explore dynamic muscle–tendon length for all muscles around the knee joint along with pelvis, hip, and ankle joint kinematics among adolescent children with varying crouch angle. Methods: Muscle–tendon length of 29 adolescent children with cerebral palsy with varying crouch angles was computed using a full-body musculo-skeletal model and expressed as a percentage of muscle–tendon length during walking compared to resting condition. Results: Children with knee flexion angle greater than 25° demonstrated lower anterior pelvic tilt and 11% greater muscle–tendon length of semimembranosus and biceps femoris during stance phase of gait compared to children with knee flexion angle less than 25° and typically developing children (p < 0.01). Conclusions: The findings of present study reported that routine bedside clinical evaluation in adolescent children with knee flexion angle greater than 25° revealed moderate shortening of hamstring muscle in supine position. Whereas instrumented objective evaluation of gait demonstrated lengthened hamstring muscle and reduced hip extension and relatively lower anterior pelvic tilt. Therefore, it may be valuable to add objective assessment of dynamic muscle–tendon length to kinematics of all lower-extremity joint motion during gait, in order to understand the muscle–joint interactions; particularly in children with severe crouch and plan specific, tailor-made surgical and non-surgical interventions. [ABSTRACT FROM AUTHOR]