The influence of smoothness and speed of stand-to-sit movement on joint kinematics, kinetics, and muscle activation patterns.

Background: Stand-to-sit (StandTS) is an important daily activity widely used in rehabilitation settings to improve strength, postural stability, and mobility. Modifications in movement smoothness and speed significantly influence the kinematics, kinetics, and muscle activation patterns of the movement. Understanding the impact of StandTS speed and smoothness on movement control can provide valuable insights for designing effective and personalized rehabilitation training programs. Research question: How do the smoothness and speed of StandTS movement affect joint kinematics, kinetics, muscle activation patterns, and postural stability during StandTS? Methods: Twelve healthy younger adults participated in this study. There were two StandTS conditions. In the reference condition, participants stood in an upright position with their feet positioned shoulder-width apart on the force plate. Upon receiving a visual cue, participants performed StandTS at their preferred speed. In the smooth condition, participants were instructed to perform StandTS as smoothly as possible, aiming to minimize contact pressure on the seat. Lower leg kinetics, kinematics, and coordination patterns of muscle activation during StandTS were measured: (1) angular displacement of the trunk, knee, and hip flexion; (2) knee and hip extensor eccentric work; (3) muscle synergy pattern derived from electromyography (EMG) activity of the leg muscles; and (4) postural sway in the anterior-posterior (A-P), medio-lateral (M-L), and vertical directions. Results: Compared to the reference condition, the smooth condition demonstrated greater eccentric knee extensor flexion and increased joint work in both the knee and hip joints. Analysis of specific muscle synergy from EMG activity revealed a significant increase in the relative contribution of hip joint muscles during the smooth condition. Additionally, a negative correlation was observed between knee extensor and vertical postural sway, as well as hip extensor work and M-L postural sway. Conclusion: Smooth StandTS facilitates enhanced knee eccentric control and increased joint work at both the hip and knee joints, along with increased involvement of hip joint muscles to effectively manage falling momentum during StandTS. Furthermore, the increased contributions of knee and hip joint work reduced postural sway in the vertical and M-L directions, respectively. These findings provide valuable insights for the development of targeted StandTS rehabilitation training.

Effects of wheelchair Tai Chi ball exercise on physical and mental health and functional abilities among elderly with physical disability.

The purpose of this study was to examine the effect of a 12-week Wheelchair Tai Chi Ball (WTCB) intervention, a combination of mind-body exercise with strength training, on physical and mental health and functional abilities among elderly with disability. Twenty-six elderly persons participated in the study, nine WTCB group participants and ten control group participants completed the study. The WTCB group practised WTCB12 twice/week for one hour each time. The control group did their daily routine without WTCB intervention. The outcomes measures were: Pain Self-Efficacy Questionnaire (PSEQ), SF-36v2 for physical and mental health, heart rate, blood pressure, range of motion and muscle strength of the dominant arm at the shoulder, elbow and wrist joints. The Mixed Model ANOVA was employed to examine the differences between and within the two groups using pre-test and post-test scores. The results demonstrated the WTCB group had significant improvements on PSEQ, general physical health and had positive effects on maintaining muscle strength at the shoulder, elbow and wrist joints as compared to the control group. The WTCB12 exercise had positive effects on self-efficacy for pain management, general physical health, and maintain upper extremity muscle strength and is a feasible exercise for elderly with disability.