Excessive Weight Bearing Compromises Foot Structure and Function Across the Lifespan - The Mechanobiology of Obesity and Related Diseases - page 149

4.1 Infants/Preschool (2-5 years)

Preschool children are at a vulnerable age in terms of structural development of the
foot. The structure and shape of a baby's foot is predominantly governed by soft
tissue, although paediatric foot shape undergoes rapid transformation as cartilage
develops into bone. The feet of infants grow most rapidly in the first 3 years of life
[ 40 ], continually changing until they attain characteristic features of adult feet
around 5-6 years of age [ 41 , 42 ]. Flat feet are common during this developmental
process, with plantar arch development predominantly occurring between the ages
of 2 and 6 years [ 40 ]. Although flat feet are common amongst infants, their
appearance often raises concern in parents, leading them to seek professional
advice and treatment for their children [ 43 ].
Given the current worldwide childhood obesity epidemic [ 44 ], one of the most
important benefits of participating in physical activity is its potential to prevent
unhealthy weight gain [ 45 ]. Prevalence studies in the United States, Great Britain
and Australia, however, indicate that approximately 30-45 % of preschool
children do not meet national physical activity guidelines [ 46 - 48 ]. Given the
health benefits of participating in physical activity for preschool children and the
proportion of children who do not meet recommendations for physical activity,
better understanding factors that influence such behaviours among young children
is paramount for successful intervention efforts and for public health promotion.
One such potential barrier to participating in physical activity is the structure and
function of children's feet.

4.1.1 Effects of Obesity in Young Children on Foot Structure

Despite the importance of the developing foot, there is limited research examining
the effects of obesity on foot structure and function in preschool aged children
[ 49 - 53 ]. In our research we found that relative to their non-overweight counter-
parts, overweight/obese preschool children (4.3 ± 0.6 years of age) have signifi-
cantly larger dimensions for foot length, ball of foot length, instep length, ball of
foot breadth, heel breadth, and instep and ball of foot circumferences [ 52 ] (Fig. 3 ).
Furthermore, overweight/obese preschool children have flatter feet than non-
overweight children, whereby the overweight/obese children had a significantly
higher Arch Index than their non-overweight counterparts (0.26 ± 0.05 vs.

0.20 ± 0.09) [ 52 ].
To investigate the possible cause of the predominance of flatter feet in over-
weight/obese children, Mickle et al. [ 52 ] measured the thickness of the midfoot
plantar fat pad using ultrasound, as well as the height of the dorsal arch, ball of foot
and plantar arch of the feet of the children (Fig. 3 ). Interestingly, the overweight/
obese children did not display a significantly thicker midfoot plantar fat pad
compared to the leaner children but rather had a significantly lower plantar arch
height than the non-overweight children. These results suggest that the flatter feet