Biomedical Engineering Reference
In-Depth Information
fasciitis) than individuals with a lower BMI (\27 kg/m 2 ;[ 107 ] ). Although it has
been suggested heel pain suffered by obese individuals is due to the effect of excess
body mass on function of the medial longitudinal arch, scientific support for the role
of altered arch mechanics in the development of plantar heel pain is, at best,
equivocal [ 90 ]. As most of the previous studies examining the relationship between
heel pain and obesity have been cross-sectional in design, it is also not clear whether
increased BMI caused the heel pain, or whether pain associated with the condition
caused participants to reduce their physical activity, thereby leading to an increase in
their BMI [ 107 ].
Others have speculated obesity promotes the development of heel pain by
reducing elasticity of the heel pad [ 114 ]. Reduced compressibility of the heel pad
in obese adults was thought to reflect a greater quantity or viscosity of adipose
tissue contained within the U-shaped septae of the fat pad [ 90 ]. However, Nass
et al. [ 103 ] found no difference in the compressibility of the heel pad under static
loading conditions in 35 normal weight and 16 overweight individuals
(BMI [ 27 kg/m 2 ), although others have found obesity reduced the elasticity of
the heel pad [ 115 ]. Further research incorporating dynamic property testing of the
heel fat pad is therefore recommended to determine the effect of obesity on the
shock absorbing capacity of the heel pad and its relationship to the development of
heel pain [ 90 ].
4.3.4 Effects of Obesity in Adults on Plantar Pressures
Understanding the effects of excessive body mass on pressures generated on the
plantar surface of adult feet during activities of daily living are important because
high pressure areas on the sole of the foot have been linked to the development of
foot pathologies such as foot ulcers [ 106 ]. Despite the importance of plantar
pressures on foot health, there is limited published research that explores the
effects of bearing excess body mass on the plantar pressures generated by adults. In
adults, a relationship between midfoot pressure distribution and relative body
weight has been reported [ 42 ]. That is, as body weight increased, loads on the
longitudinal portion of the plantar plate increased [ 116 ]. However, this relationship
between body mass and plantar pressure in adults was not found by Cavanagh
et al. [ 117 ] when examining the plantar pressure distributions from 107 feet,
although obese individuals were not specifically recruited when establishing the
study cohort. In a study by Gravante et al. [ 93 ], in which obese individuals were
specifically recruited, the 23 obese women and 15 obese men displayed signifi-
cantly higher plantar pressures when standing relative to the 34 non-obese controls
(peak pressure: +45.5 % for obese women and +40.5 % for obese men). Teh et al.
[ 110 ] also noted increases in total force and forefoot peak pressures during relaxed
standing as BMI increased. It was speculated that the higher plantar pressures
generated by the obese participants might have negative ramifications for foot
function over the longer term [ 93 ], although these studies were restricted to an
analysis of static plantar pressures.
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