Abstract:
Habitually barefoot (HB) children from the Kalenjin tribe of Kenya are known
for their high physical activity levels. To date, there has been no compre-
hensive assessment of foot structure and function in these highly active and
HB children/adolescents and link with overuse injuries. Purpose: The aim of
this research is to assess foot structure, foot function, injury and physical
activity levels in Kenyan children and adolescents who are HB compared
with those who were habitually shod (HS). Methods: Foot structure, func-
tion, injury prevalence, and physical activity levels were studied using two
studies with equal numbers of HS and HB. HS and HB children and adoles-
cents were matched for age, sex, and body mass. Foot arch characteristics,
foot strength, and lower-limb injury prevalence were investigated in Study 1
(n = 76). Heel bone stiffness, Achilles tendon moment arm length and
physical activity levels in Study 2 (n=62). Foot muscle strength was mea-
sured using a strength device TKK 3360 and heel bone stiffness by bone
ultrasonometry. The moment arm length of the Achilles tendon was esti-
mated from photographs and physical activity was assessed using ques-
tionnaires and accelerometers. Results: Foot shortening strength was
greater in HB (4.8 T 1.9 kg vs 3.5 T 1.8 kg, P G 0.01). Navicular drop was
greater in HB (0.53 T 0.32 cm vs 0.39 T 0.19 cm, P G 0.05). Calcaneus
stiffness index was greater (right 113.5 T 17.1 vs 100.5 T 116.8, P G 0.01
left 109.8 T 15.7 vs 101.7 T 18.7, P G 0.05) and Achilles tendon moment
arm shorter in HB (right, 3.4 T 0.4 vs 3.6 T 0.4 cm, P G 0.05; left, 3.4 T 0.5 vs
3.7 T 0.4 cm, P G 0.01). Lower-limb injury prevalence was 8% in HB and
61% in HS. HB subjects spent more time engaged in moderate to vigorous
physical activity (60 T 26 minIdj1 vs 31 T 13 minIdj1
; P G 0.001). Con-
clusions: Significant differences observed in foot parameters, injury prev-
alence and general foot health between HB and HS suggest that footwear
conditions may impact on foot structure and function and general foot
health. HB children and adolescents spent more time engaged in moderate
to vigorous physical activity and less time sedentary than HS children
and adolescents.