Are flat feet a disadvantage in performing unilateral and bilateral explosive power and dynamic balance tests in boys? A school-based study.

Background: Little evidence has been provided regarding physical performance and flat-footedness in school-age children. Although flat feet may decrease the level of motor performance, findings remain inconsistent. Therefore, the main purpose of the study was to determine whether children with flat feet had poorer physical task performance, compared to normal-footed children.

Methods: A total of 208 primary school boys were included in the study (107 normal-footed and 101 flatfooted boys). Flat footedness (< 42°) was determined using Clark's method. The children were tested by a set of unilateral and bilateral tests selected from the area of ​​explosive power and dynamic balance which included: (i) countermovement jump, (ii) standing broad jump, (iii) the triple crossover hop for distance test, (iv) maximal sprinting speed over 10, 20 and 40 m and (v) the Star Excursion Balance Test. Differences were adjusted for age, body mass index, peak height velocity and physical activity.

Results: Flat footed children exhibited significantly poorer results in bilateral standing broad jump (effect size [ES] = 0.34), unilateral standing broad jump for dominant (ES = 0.31) and non-dominant leg (ES = 0.20), the triple crossover hop for distance test for dominant (ES = 0.24) and non-dominant leg (ES = 0.23) and the Star Excursion Balance Test (ES = 0.23-0.43) and were slower in maximal sprinting speed test over 20 m (ES = 0.25) and 40 m (ES = 0.30).

Conclusions: This study shows that children with flat feet performed poorer in some physical performance tasks, compared to the normal feet counterparts.