Evaluation of implicit associations between back posture and safety of bending and lifting in people without pain

Background and aims: Despite lack of support from recent in vivo studies, bending and lifting (especially with a round-back posture) are perceived as dangerous to the back. In light of this view, it has been proposed that pain-free people may hold a common implicit belief that is congruent with the idea that bending and lifting with a round-back represents danger to a person's back, however this has not been evaluated. The aims of this study were: (1) to evaluate implicit associations between back posture and safety related to bending and lifting in pain-free people; (2) to explore correlations between the implicit measure and explicit measures of back beliefs, fear of movement and safety of bending; (3) to investigate self-reported qualitative appraisal of safe lifting. Methods: Exploratory cross-sectional study including 67 pain-free participants (no pain, or average pain <= 3/10 for less than one week over the previous 12 months) (52% male), who completed an online survey containing demographic data and self-reported measures of: fear of movement (Tampa Scale for Kinesiophobia for General population - TSK-G), back beliefs (Back Pain Attitudes Questionnaire BackPAQ), and bending beliefs (Bending Safety Belief - BSB - a pictorial scale with images of a person bending/lifting with round and straight back postures). Implicit associations between back posture and safety related to bending and lifting were evaluated with the Implicit Association Test (IAT). A qualitative assessment of descriptions of safe lifting was performed. Results: An implicit association between "danger" and "round-back" bending/lifting was evident in all participants (IAT(D-score) = 0.65 (SD = 0.45; 95% CI [0.54, 0.76]). Participants' profile indicated high fear of movement, unhelpful back beliefs, and perceived danger to roundback bending and lifting (BSBThermometer: 5.2 (SD = 3.8; 95% CI [4.26, 6.13] range -10 to 10; t((67)) = 11.09, p < 0.001). There was a moderate correlation between IAT and BSBThermometer (r =0.38, 95% CI [0.16, 0.62]). There were weaker and nonstatistically significant correlations between IAT and TSK-G (r = 0.28, 95% CI [-0.02, 0.47]), and between IAT and BackPAQ(Danger) (r = 0.21, 95% CI [-0.03, 0.45]). Qualitative assessment of safe lifting descriptions indicated that keeping a "straight back" and "squatting" when lifting were the most common themes. Conclusions: Pain-free people displayed an implicit bias towards bending and lifting with a "round-back" as dangerous. Our findings support the idea that pain-free people may have a pre-existing belief about lifting, that the back is in danger when rounded. Research to evaluate the relationship between this implicit bias and lifting behaviour is indicated.