Association between Trunk Flexion and Physical Activity in Patient Care Unit Workers

The purpose of this pilot study was to characterize the direct measure of physical activity levels and the trunk posture (as a proxy for physical load) among a convenience sample of 49 Patient Care Unit workers (nurses and patient care assistants) for a single work shift. We tested the hypotheses that Patient Care Unit (PCU) worker’s increased trunk posture is associated with their direct measure of physical activity levels during one work-shift. To assess the physical activity and physical load component all participants wore an accelerometer and an inclinometer respectively. A correlation analysis was performed to assess the association between parameters of physical activity (minutes in sedentary activity, minutes in lifestyle activity, minutes in light activity and minutes in moderate activity) with parameters of physical load (number of forward trunk bends to 20° per shift, number of forward trunk bends to 45° per shift). Workers were recruited from two hospitals in Boston, Massachusetts. Eleven participants spent 86% of the time at work with a trunk flexion lower than 15°, they were considered at low exposure for back disorders. Seven PCU workers spent 33% of their work time with a trunk flexion higher than 20°, they were considered at high exposure. Twenty-one workers were classified at a medium exposure for back disorders. A high correlation was found between number of forward trunk bending to 20° per shift (spearman’s correlation: 0.56, p<0.001) with minutes in lifestyle activity. In addition, a high correlation was found among number of forward trunk bending to 45° per shift with minutes in lifestyle activity and minutes in light activity (spearman’s correlation: 0.41, p=0.005 and 0.37, p=0.01 respectively). These results suggest that physical load at work during a single shift does not contribute to meet moderate or vigorous activity levels which are the activity levels that have substantial health benefits. Further studies with a bigger sample size would be recommended to assess the association between physical loads and physical activities for more than one shift to corroborate our findings.