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Running speed does not influence the asymmetry of kinematic variables of the lower limb joints in novice runners

Jiang Xinyan, Chen Hairong, Sun Dong, Baker Julien S., Gu Yaodong

Acta of Bioengineering and Biomechanics

2021

Vol. 23, no. 1

69--81

Purpose: The purpose of this study was to evaluate kinematic variables at 5 running speeds (8 to 12 km/h), for the asymmetry between lower limbs. We also investigated the effects of running speed on the bilateral asymmetry of the lower limb joints kinematic variables among novice runners. Methods: Kinematic (200 Hz) running data were collected bilaterally for 17 healthy male novice runners (age: 23.1 ± 1.3 years, height: 1.77 ± 0.04 m, mass: 72.3 ± 4.57 kg, BMI: 23.1 ± 1.0 kg/m2) running on a treadmill at 5 fixed speeds (8, 9, 10, 11 and 12 km/h) in a randomized order. Symmetry angles (SA) were calculated to quantify gait asymmetry magnitude at each running speed. Results: Overall, SPM analysis using paired t-tests revealed significant joints kinematic differences between the left lower limb and the right lower limb at each running speed. Significant differences between limbs were found for all joint kinematic variables in the ankle and hip, regardless of running speed. As for the knee angle, significant differences between legs were only found during the running speed of 11 km/h. For knee angle velocity, significant differences between legs were found in all running speeds except for 8 km/h. However, there was no noticeable difference in asymmetry values across running speeds. Conclusions: The findings of the current study indicate that gait asymmetry of joint kinematics variables between lower limbs during running is apparent in healthy novice runners. Meanwhile, running speed does not influence lower limb joints kinematic asymmetry among novice runners.

Yarn twisting

Palaniswamy K., Mohamed P.

Autex Research Journal

2005

Vol. 5, no. 2

87--90

The mechanism of twist insertion to the strand during ring spinning has been studied. The twisting of the strand occurs not only due to the rotation of twisting elements, but also due to the winding of yarn on the package. When the yarn is wound on a stationary cop by gripping and winding the yarn by hand, for every coil of yarn wind one turn of twist to the yarn is inserted. But the same yarn is over-end withdrawn from the cop, and all twists inserted during winding are removed during unwinding. Over-end unwinding rotates the yarn in the opposite direction. Since the yarn from the cop is over-end withdrawn during winding, the spindle speed is taken for calculating the twist in the yarn, whereas the flyer speed is taken for calculating twist in the roving due to the parallel unwinding of roving during spinning.