Functional behaviour of spinal muscles after training with an exercise device developed to recruit and train postural muscles

Abstract

This study investigated the effects of a single exercise session using a device developed for postural muscle training on the function of postural muscles in healthy, pain free individuals. During standardised rapid arm movements, timing of onset of electromyography (EMG) was measured using intramuscular and surface recordings of the transversus abdominis (TrA), obliquus internus abdominis (OI), obliquus externus abdominis (OE), lumbar multifidus (LM) and lumbar erector spinae (LES) muscles. A single exercise session with the device led to significantly (main effect of time: P = 0.03) earlier LES EMG onset in advance of the postural perturbation induced by rapid forward arm movements from -1 ms (SD: 32 ms) at baseline to -11 ms (SD: 27 ms) post-exercise and -16 ms (SD: 22 ms) at 10-min Wash-Out after the FRED exercise bout. The timing of EMG onset of the other trunk muscles was not affected by the single bout of exercise. A significant correlation was found between background activity and the EMG onset times of of TrA (r = 0.6; P < 0.001), OI (r = 0.59; P < 0.001), LES (r = 0.32; P = 0.046) and LM (r = 0.77; P < 0.001). Higher levels of trunk muscle background activity were associated with later onset times. The present findings suggest that a single exposure to the postural training device can induce small changes in spinal muscle function in healthy pain free individuals.

The Effects of Abdominal Hypopressive Training on Postural Control and Deep Trunk Muscle Activation: A Randomized Controlled Trial

“…In healthy individuals, TrA activity is usually triggered before any postural disturbance, to protect the lumbar region from imposed forces. [8]. If this perturbation is not anticipated, balance disruption may occur [9].…”

Intermittent short-arm centrifugation is a partially effective countermeasure against upright balance deterioration following 60-day head-down tilt bed rest

“…Holding a weight likely produces a tonic activation of the trunk muscles, which may affect the detection of trunk muscle onsets. A previous study showed that tonic activation delayed the onsets of trunk muscles during RAMT (70). A higher background muscle activity before the RAMT is likely to increase the level of descending drive, rendering 'additional' muscle activity unnecessary until later (70).…”

“…This algorithm uses statistically optimal decisions to detect changes in EMG amplitude. The automatically detected times of change in amplitude were then visually inspected to avoid spurious "onset candidates" not related to the arm movement, e.g., ECG bursts or other movement artefacts (70). Both visual determination and approximated generalized likelihood ratio method of EMG onset has been found to be highly repeatable between days during RAMT using a combination of sEMG and iEMG (25,64).…”

“…A previous study showed that tonic activation delayed the onsets of trunk muscles during RAMT (70). A higher background muscle activity before the RAMT is likely to increase the level of descending drive, rendering 'additional' muscle activity unnecessary until later (70). Moreover, algorithms to detect EMG onset are sensitive to the level of background activity (more specifically, the signal-to-noise ratio), so that larger activity levels during baseline may result in a later onset detection.…”

The Effects of Reconditioning Exercises Following Prolonged Bed Rest on Lumbopelvic Muscle Volume and Accumulation of Paraspinal Muscle Fat

“…Participants were instructed to stand with their knees slightly bent with a relaxed upper body posture while keeping the lower limbs moving in a slow, controlled manner with minimal variability in their movement speed throughout the cycle ( Weber et al, 2018 ). Visual feedback of the rotational frequency of the footplates was provided on a screen in front of the participant, who was asked to maintain a frequency of 0.42 revolutions per second with as constant a rotational frequency as possible throughout each complete rotation ( Weber et al, 2018 ). The FRED training time was increased incrementally for the first 5 days from 6 to up to 25 min of training, in 3–5 min intervals.…”