Measurement and perceptions: Physical activity in people with low back pain

Physical activity (PA) is recommended for the management of low back pain (LBP). This research was undertaken to: establish the use of accelerometers as an outcome measure in studies investigating the free-living PA of people with LBP; explore the free-living PA of people receiving physiotherapy for LBP; and compare patterns of PA between people with acute low back pain (ALBP) and people with chronic low back pain (CLBP). PA was measured with the RT3 accelerometer (Stayhealthy Inc., Monrovia, California, USA) which is an objective measure of PA. In addition, perceptions of being physically active with LBP and the coherence between the lived experience of LBP and physiotherapy management were explored. A review of PA and LBP literature found that while ‘advice to stay active’ is recommended, there is a paucity of research exploring the free-living PA of people with LBP with an objective measure, such as an accelerometer. It is unknown if free-living PA is altered in people with LBP compared to healthy individuals. Likewise, the psychometric properties of many accelerometers are also unknown and this may account for some discrepancies in results. A pilot study was undertaken in healthy volunteers (N = 21) to determine the minimum number of days per week of valid RT3 data required to reliably estimate PA, and the validity and utility of the RT3. The RT3 was found to have acceptable utility and good validity, and a minimum of four days of RT3 data are required to reliably assess PA. A mixed methods (MM) study explored: the responsiveness of the RT3 to measure change in PA, compare patterns of PA between people with ALBP or CLBP (N = 111); and semi-structured interviews were conducted with a sub-group of the LBP participants to explore perceptions of PA (N = 13). The RT3 demonstrated limited responsiveness to perceived change in PA, measured with the Global Rating of Change (GROC), at week six only; perceived PA and measured PA appear to be different constructs. A significant interaction between LBP and week of PA measurement was found. Neither LBP group met the recommendation for sustained bouts of moderate intensity PA per day. Interviewees knew that PA was an important aspect in the management of their LBP. However, being active was dependent on perceived control and this was unrelated to LBP classification. The use of “trial and error” strategies when increasing PA resulted in a flare of LBP, the reinforcement of negative PA beliefs and behaviours, and poor treatment coherence. Further research into the design and psychometric properties of accelerometers is warranted. People with ALBP have different PA patterns to people with CLBP; yet both groups demonstrate an inability to endure sustained and repetitive bouts of moderate intensity PA. People with LBP are unsure how to return to habitual PA. Physiotherapists may need to consider treatment coherence, and provide more time and support for changing unhelpful perceptions and PA behaviours. To conclude, perceptions of PA are not the same construct as objectively measured PA, but both constructs are important