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Risk factors for low back pain (LBP) flares have been considered about self-reported measures. This case-crossover study aimed to investigate whether (1) objective measures of physical activity and sleep were associated with the risk of experiencing LBP flares and (2) these associations differed for flares defined as pain 2 or more points greater than average pain over the period using an 11-point Numerical rating scale (0-no pain and 10-worst pain imaginable) (pain-defined flare: PDF) and flares identified by participants according to a broader definition that considered emotions or coping (self-reported flare [SRF]). We included 126 participants who had experienced LBP for3 months. Physical activity and sleep were monitored for 28 days using wearable sensors. Occurrence of flares (PDF or SRF) was assessed daily using a smartphone application. Data on exposure to risk factors 1, 2, and 3 days preceding PDF or SRF were compared with nonflare control periods. Conditional logistic regression determined association between each factor and flares. Data show that day-to-day variation in physical activity and in-bed time are associated with the risk of LBP flares, but associations differ depending on how flare is defined. Longer in-bed time increased the risk of PDF but not SRF. Although physical activity was not associated with the risk of PDF, greater sedentary behaviour increased the risk of SRF and being more physically active decreased the risk for SRF. These results highlight the potential role of targeting sleep and physical activity in interventions to prevent LBP flares and indicate that risk factors differ depending on how LBP flares are defined.

Inhibiting ongoing responses when environmental demands change is a critical component of human motor control. Experimentally, the stop signal task (SST) represents the gold standard response inhibition paradigm. However, an emerging body of evidence suggests that the SST conflates two dissociable sources of inhibition, namely an involuntarily pause associated with attentional capture and the (subsequent) voluntary cancellation of action. The extent to which these processes also occur in other response tasks is unknown.24 younger (20-35 years) and 23 older (60-85 years) adults completed a series of tasks involving rapid unimanual or bimanual responses to a visual stimulus. A subset of trials required cancellation of one component of an initial bimanual response (i.e., selective stop task; stop left response, continue with right response) or enacting an additional response (e.g., press left button as well as right button). Critically, both tasks involved some infrequent stimuli which bore no behavioural imperative (i.e., they had to be ignored).EMG recordings of voluntary responses during the stopping tasks revealed bimanual covert responses (i.e., muscle activation which was suppressed before a button press ensued), consistent with a pause process, following both stopandignore stimuli, before the required response was subsequently enacted. Critically, we also observed the behavioural consequences of a similar involuntary pause in trials where action cancellation was not part of the response set (i.e., when the additional stimulus required additional action or ignoring, but not inhibition). The findings shed new light on the mechanisms of inhibition and their generalisability to other task contexts.

[Abstract] Objective. Understanding sleeping behaviours could improve prevention and treatment of sleep problems and associated health conditions. This study aimed to evaluate a method to assess body posture and movement during sleep using trunk-worn accelerometers for 28 nights. Approach. Participants (50 adults with low back pain (66% female); aged 32(±9) years) wore two activPAL-micro sensors (thigh, trunk) during their normal daily life for 28 consecutive days. Parameters related to body posture (e.g. time spent lying supine or prone) and movement (e.g. number of turns) during sleep were calculated for each night. Average values for each parameter were identified for different periods, the Spearman–Brown Prophecy Formula was used to estimate the minimum number of nights required to obtain a reliable estimate of each parameter, and repeatability of measures between different weeks was calculated. Main results. Participants spent 8.1(±0.8) h asleep and most time (44%) was spent in a supine posture. The minimum number of nights required for reliable estimates varied between sleep parameters, range 4–21 nights. The most stable parameters (i.e. requiring less than seven nights) were 'average activity', 'no. of turns', 'time spent prone', and 'posture changes in the first hour'. Some measures differed substantially between weeks. Significance. Most sleep parameters related to body posture and movement require a week or more of monitoring to provide reliable estimates of behaviour over one month. Notably, one week may not reflect behaviour in another week, and the time varying nature of sleep needs to be considered. National Health and Medical Research Council (Australia); APP1091302 National Health and Medical Research Council (Australia); APP1079078 National Health and Medical Research Council (Australia); PWH – APP1102905

Although risk factors for new low back pain (LBP) episodes and acute-to-chronic transition have been identified, risk factors for flares of LBP remain largely unknown. This case-crossover study aimed to identify: (1) risk factors LBP flares and (2) whether risk factors differed when flare is defined by pain increase (pain-defined flare: PDF) or identified by participants according to a broader flare definition that considered emotions and coping (self-reported flare: SRF).One hundred and twenty-six participants with LBP for 3 months were included. Candidate risk factors and flares (PDF/SRF) were assessed daily using a smartphone application for 28 days. Data on exposure to risk factors one, two and three days preceding PDF/SRF were compared to control periods. Conditional logistic regression estimated associations between risk factors and PDF/SRF.Odds of PDF and SRF were increased by poor sleep quality and morning pain. Good sleep quality reduced odds of flare. Odds for increased pain (PDF), but not SRF, were increased after days with higher afternoon and evening pain, fatigue, fear of physical activity and leisure physical activity.LBP flare has been largely ignored but is more reflective of the LBP experience than conventional definitions of acute, sub-acute and chronic LBP. This study highlights risk factors for flare and that these differ depending on whether flare is defined by pain alone (PDF) or a broad multidimensional definition (SRF). Potential targets to reduce the intensity/frequency of LBP flares are identified, with strong indication for the potential role of sleep intervention to mitigate LBP flare risk.