Pain catastrophizing moderates changes in spinal control in response to noxiously induced low back pain.

It is generally accepted that spine control and stability are relevant for the prevention and rehabilitation of low back pain (LBP). However, there are conflicting results in the literature in regards to how these variables are modified in the presence of LBP. The aims of the present work were twofold: (1) to use noxious stimulation to induce LBP in healthy individuals to assess the direct effects of pain on control (quantified by the time-dependent behavior of kinematic variance), and (2) to assess whether the relationship between pain and control is moderated by psychological features (i.e. pain catastrophizing (PC) and kinesiophobia). Participants completed three conditions (baseline, pain, recovery) during a task involving completion of 35 cycles of a repetitive unloaded spine flexion/extension movement. The neuromuscular control of spine movements was assessed during each condition using maximum finite-time Lyapunov exponents (λmax). Nociceptive stimulus involved injection of hypertonic saline into the interspinous ligament, eliciting pain that was greater than baseline and recovery (p<0.001). Although there was no overall main effect of the nociceptive stimulation (i.e. pain) on λmax when the whole group was included in the statistical model (p=0.564), when data were considered separately for those with high and low PC, two distinct and well established responses to the pain were observed. Specifically, those with high PC tightened their control (i.e. stabilized), whereas those with low PC loosened their control (i.e. destabilized). This study provides evidence that individuals' beliefs and attitudes towards pain are related to individual-specific motor behaviors, and suggests that future research studying spine control/stability and LBP should account for these variables.

Evaluating the Ergonomic Benefit of a Wrist Brace on Wrist Posture, Muscle Activity, Rotational Stiffness, and Peak Shovel-Ground Impact Force During a Simulated Tree-Planting Task.

Background Tree planters are at a high risk for wrist injury due to awkward postures and high wrist loads experienced during each planting cycle, specifically at shovel-ground impact. Wrist joint stiffness provides a measure that integrates postural and loading information. Objective The purpose of this study was to evaluate wrist joint stiffness requirements at the instant of shovel-ground impact during tree planting and determine if a wrist brace could alter muscular contributions to wrist joint stiffness. Method Planters simulated tree planting with and without wearing a brace on their planting arm. Surface electromyography (sEMG) from six forearm muscles and wrist kinematics were collected and used to calculate muscular contributions to joint rotational stiffness about the wrist. Results Wrist joint stiffness increased with brace use, an unanticipated and negative consequence of wearing a brace. As a potential benefit, planters achieved a more neutrally oriented wrist angle about the flexion/extension axis, although a less neutral wrist angle about the ulnar/radial axis was observed. Muscle activity did not change between conditions. Conclusion The joint stiffness analysis, combining kinematic and sEMG information in a biologically relevant manner, revealed clear limitations with the interface between the brace grip and shovel handle that jeopardized the prophylactic benefits of the current brace design. This limitation was not as evident when considering kinematics and sEMG data independently. Application A neuromechanical model (joint rotational stiffness) enhanced our ability to evaluate the brace design relative to kinematic and sEMG parameter-based metrics alone.

The effect of rest break schedule on acute low back pain development in pain and non-pain developers during seated work.

A significant portion of the population (25-50%) is known to develop acute low back pain (LBP) within a bout of prolonged sitting. Previous research has supported the use of frequent rest breaks, from seated office work, in order to reduce self-reported LBP, however, there is limited consensus about the recommended frequency and duration of rest breaks. This may be due to the limited consideration of individual differences in acute LBP development. The purpose of this study was to examine the effect of three different standing rest-break conditions on a group of pain developers (PD) and non-pain developers (NPD) engaged in prolonged seated work. Twenty participants completed four one-hour-long bouts of seated typing: Condition A - no rest; Condition B - 5 min of standing rest every 30 min; Condition C - 2.5 min of standing rest every 15 min; Condition D - 50 s of standing rest every 5 min. Self-reported LBP, self-reported mental fatigue and 30-s samples of EMG were collected every 10 min throughout each session. Eight out of 20 participants (40%) reported LBP during Condition A (classified as PD). Only PD demonstrated clinically relevant increases in LBP across conditions where Conditions B, C, or D provided some relief, but did not restore pain scores to their original level, prior to sitting. PD and NPD developed mental fatigue equally, with Conditions B and D helping to reduce fatigue. No differences in productivity were observed between conditions or groups and no main effects were observed for muscle activity, median power frequency or co-contraction. These data suggests that frequent, short, standing rest breaks may help to reduce symptoms of LBP, however they are only a temporary solution as PD still developed clinically important LBP, even with frequent rest breaks.

A review of culturally adapted versions of the Oswestry Disability Index: the adaptation process, construct validity, test-retest reliability and internal consistency.

The Oswestry Disability Index (ODI) is a self-report-based outcome measure used to quantify the extent of disability related to low back pain (LBP), a substantial contributor to workplace absenteeism. The ODI tool has been adapted for use by patients in several non-English speaking nations. It is unclear, however, if these adapted versions of the ODI are as credible as the original ODI developed for English-speaking nations. The objective of this study was to conduct a review of the literature to identify culturally adapted versions of the ODI and to report on the adaptation process, construct validity, test-retest reliability and internal consistency of these ODIs. Following a pragmatic review process, data were extracted from each study with regard to these four outcomes. While most studies applied adaptation processes in accordance with best-practice guidelines, there were some deviations. However, all studies reported high-quality psychometric properties: group mean construct validity was 0.734 ± 0.094 (indicated via a correlation coefficient), test-retest reliability was 0.937 ± 0.032 (indicated via an intraclass correlation coefficient) and internal consistency was 0.876 ± 0.047 (indicated via Cronbach's alpha). Researchers can be confident when using any of these culturally adapted ODIs, or when comparing and contrasting results between cultures where these versions were employed. Implications for Rehabilitation Low back pain is the second leading cause of disability in the world, behind only cancer. The Oswestry Disability Index (ODI) has been developed as a self-report outcome measure of low back pain for administration to patients. An understanding of the various cross-cultural adaptations of the ODI is important for more concerted multi-national research efforts. This review examines 16 cross-cultural adaptations of the ODI and should inform the work of health care and rehabilitation professionals.