Changes in spine loading patterns throughout the workday as a function of experience, lift frequency, and personality

Background contextPsychosocial stressors have been associated with low back pain reporting. However, response to psychosocial risk factors may be dependent on the individual's personality type that, in turn, can affect muscle recruitment and spine loading. This study explores how personality might be associated with spine loading during repetitive lifting performed throughout an entire work shift.PurposeAssess spine loading as a function of an individual's personality type during repetitive, long-term exposure to a materials handling tasks.Study designLaboratory experiment where experienced and inexperienced participants performed repetitive, asymmetric lifts at various load and lift frequency levels throughout a series of 8-hour exposure periods. Spine loads were monitored throughout the work period.Patient sampleTwelve novice and 12 experienced materials handlers who were asymptomatic for back pain.Outcome measuresSpine compression, anterior-posterior (A/P) shear, and lateral shear at the L5–S1 level.MethodsParticipants were categorized into personality types based upon the Myers-Briggs personality type indicator. An electromyography-assisted biomechanical model was used to assess spine compression, A/P shear, and lateral shear throughout the exposure period.ResultsThe results indicate that intuitors had higher shear spinal loading regardless of moment exposure, lift frequency, and time through the work period, compared with the sensor personality type. In addition, higher spine compressive and shear forces occurred in the perceiver personality compared with the judgers' personality trait, regardless of moment and, often, lift frequency. Novice lifters typically experienced greater spine loading.ConclusionsThe results suggest that when there exists a personality–job environment mismatch, spinal loading increases via an increase in antagonistic co-contraction. The trends suggest that inherent personality characteristics may play a role in one's motor control strategies when performing a repetitive lifting task.