The influence of increased passive stiffness of the trunk and hips on balance control during reactive stepping

Application of Principal Component Analysis to Forward Reactive Stepping: Whole-body Movement Strategy Differs as a Function of Age and Sex

BACKGROUND

Differences in reactive stepping strategy to recover balance have been investigated as a function of age and sex, but to date have been measured using discrete step or joint specific measures. It is unknown how whole-body strategy or underlying motor control objectives differ between age and sex groups in forward reactive stepping.

RESEARCH QUESTION

Does whole-body movement and/or motor control strategy differ as a function of age or sex in a forward reactive step to maintain balance?

METHODS

Forty young and older adults (45 females, 35 males) participated in this study. All participants performed five reactive stepping trials in response to a forward balance perturbation while whole-body kinematics and ground reaction forces were collected. Features of whole-body movement strategy were determined using a principal component analysis model. Average principal component (PC) scores were compared between groups as a measure of whole-body movement strategy and within participant relative standard deviation of PC scores were compared to determine if motor control objectives differed across groups.

RESULTS

Significant differences in reactive stepping strategy were observed both as a function of age and sex. Older adults had a greater step length and width, greater anterior trunk and pelvis translation, greater knee flexion angles and anterior translation of the hip joint on the stepping leg compared to young participants. Males had lesser step length and width, as well as greater trunk flexion compared to females. No differences in relative standard deviation of PC scores were observed between age or sex-based groups suggesting that motor control objectives were similar between groups.

SIGNIFICANCE

This study demonstrates how whole-body movement strategy differs as a function of age and sex, which explains why previously reported discrete outcomes occur. Additionally, it does not seem that motor control strategy objectives differ between age or sex groups in forward reactive stepping.

Exergaming Using Postural Feedback From Wearable Sensors and Exercise Therapy to Improve Postural Balance in People With Nonspecific Low Back Pain: Protocol for a Factorial Pilot Randomized Controlled Trial

Background

Physical exercise is a common treatment for people with low back pain (LBP). Wearable sensors that provide feedback on body movements and posture during exercise may enhance postural balance and motor control in people with LBP.

Objective

This study aims to investigate whether physical exercising with postural feedback (EPF) improves postural balance, motor control, and patient-reported outcomes in people with LBP.

Methods

The study was an assessor-blinded 2×2 factorial trial. We planned to recruit 80 participants with nonspecific LBP who did not receive treatment for LBP. In addition, we aimed to recruit 40 patients with chronic, nonspecific LBP who were receiving exercise therapy (ET) at the University Hospital Zurich. Both ET patients and participants without treatment were randomized to receive either an additional EPF intervention or no additional intervention. This resulted in four different combinations of interventions: ET+EPF, ET, EPF, and no intervention. The participants underwent outcome assessments at inclusion (T1); 3 weeks later, at randomization (T2); after an intervention period of 3 weeks with a predefined exercise schedule for participants receiving EPF (T3); and after an additional 6 weeks, during which participants assigned to the EPF groups could exercise as much as they wished (T4). Patients receiving ET completed their regularly prescribed therapies during the study period. Balance was assessed during quiet standing on a force platform, and motor control was assessed during a lifting task and a waiter’s bow task. Physical activity was recorded using an activity tracker and the participants’ mobile phones during the study. The predefined EPF schedule consisted of nine sessions of 20 minutes of exercise with a tablet and inertial measurement unit sensors at home. Participants performed a series of trunk and hip movements and received feedback on their movements in a gamified environment displayed on the tablet.

Results

The first participant was recruited in May 2019. Data collection was completed in October 2020, with 3 patients and 32 eligible people without therapy who passed the eligibility check.

Conclusions

Although it will not be possible to investigate differences in patients and people without other therapies, we expect this pilot study to provide insights into the potential of EPF to improve balance in people with LBP and adherence to such interventions.

International Registered Report Identifier (IRRID)

DERR1-10.2196/26982