Reduced Neuromuscular Performance in Night Shift Orthopedic Nurses: New Insights From a Combined Electromyographic and Force Signals Approach

<p>The effect of sleep&ndash;wake rhythm disruption on neuromuscular control and muscle</p> <p>fatigue has received little attention. Because nurse shift work is so varied, including</p> <p>overnight duty, rotating shift schedules, early awakening, and interrupted nocturnal</p> <p>sleep, it offers an interesting model to study this paradigm. It has been investigated</p> <p>so far using only subjective markers. A combined approach based on the simultaneous</p> <p>analysis of surface electromyographic (sEMG) and force signals can objectively detect</p> <p>possible deficits in neuromuscular control and muscle fatigue. With this study we</p> <p>investigated neuromuscular activation and muscle contraction capacity at submaximum</p> <p>and maximum level in nurses working two night-shift schedules and compared them to</p> <p>levels in nurses working entirely in day shifts. Sleep quality and activity levels were also</p> <p>assessed. The study sample was 71 nurses grouped by their shift work schedule: night</p> <p>shift for 5 days (NS5, n = 46), night shift for 10 days (NS10, n = 9), and only day/swing</p> <p>shift (DS, n = 16). Before and after the shift-work cycle, maximum voluntary contraction</p> <p>(MVC) force and muscle activation, neuromuscular control, and muscle fatigability were</p> <p>measured in the finger flexor muscles. Activity level and sleep quality during the shiftwork</p> <p>cycle were recorded with a wrist actigraph. After the shift-work cycles, MVC force</p> <p>and muscle activation were decreased (􀀀11 &nbsp;3% and 􀀀33 &nbsp;3%, p &lt; 0.001) as</p> <p>was neuromuscular control (􀀀36 &nbsp;8%, p = 0.007), whereas muscle fatigability was</p> <p>increased (C 19 &nbsp;9%, p = 0.006) in the NS5 and the NS10 group. Sleep quality was</p> <p>lower in the NS5 and the NS10 group (􀀀8 &nbsp;1.8% and 􀀀15%3, respectively, p &lt; 0.001),</p> <p>while the activity level for the three groups was similar. There was a clear reduction</p> <p>in neuromuscular control and an increase in muscle fatigue in the nurses working the</p> <p>night shift. These findings may inform of work schedule planning or recommendations</p> <p>for devising new recovery strategies to counteract neuromuscular alterations in night</p> <p>shift nurses.</p>