BACKGROUND: Little research is available on low back biomechanical
stresses that obese and overweight workers experience from manual load
lifting.
OBJECTIVE: The study objective was to quantitatively evaluate low
back biomechanical stresses of severely obese (BMI ≥ 35 kg/m2)
workers during manual lifts of moderate load weights.
METHOD: Twenty severely obese and 20 normal weight participants
performed infrequent lifting in 16 task conditions. In each task condition,
NIOSH recommended load weights were computed for the origin and destination
of lift and were employed as the load weights. Optical motion capture was
performed to collect lifting posture data. For each participant and each
lifting condition, L5/S1 disc compression forces were computed at the origin
and destination of lift using a static low back biomechanical model.
RESULTS: The L5/S1 disc compression forces estimated for the
severely obese participants ranged from 3000N to 8500N and many exceeded the
3400N NIOSH action limit by large margins. Group mean disc compression force
was significantly larger for the severely obese than the normal weight
group.
CONCLUSION: In light of previous research on spine, bone and
obesity, the study results seem to suggest that severely obese individuals
are likely at an increased risk of lifting-related low back pain compared
with normal weight individuals.
