Weekly changes of gait temporal parameters during the first two months of independent walking: A longitudinal study

Research question: Development of independent gait: what happens during the first two months after the onset of walking? Introduction: A recent study indicated that toddlers at the onset of independent walking show a developmental shift after two months of walking experience: this shift may be caused by the achievement of an increased postural control, which is reflected in significant changes in the trends of gait parameters [1]. To the author knowledge, longitudinal data have never been collected more frequently than once a month, in particular during this first very important period of gait maturation. The aim of the present study is to observe weekly a relatively large group of infants using inertial sensors during the first two months of independent walking. Quantitative longitudinal measurements of gait parameters can provide the basis for better understanding the development of human gait and the mechanisms behind. Materials and methods: Twenty healthy infants (77 ± 2 cm, 9.3 ± 0.8 kg, 13 ± 2 months) were included in the study. All of the infants had no known developmental delays. The tests were scheduled once a week after the onset of independent walking for 2 months. Two tri-axial wireless inertial sensors (OPALS, Apdm, USA) were mounted on the right and on the left leg, respectively. The participants were asked to walk straight in the room. Heel-strike and toe-off instants were estimated from the angular velocity of the lower limbs [2]. Median stride (strT), swing and stance times were calculated for both right and left leg; swing and stance times were expressed as percentage of strT (staT% and staT%). Results: Presented results are preliminary and are based on 10 toddlers who completed all the scheduled tests. Median strT showed a slow constant decrease during the analysed period (from 0.8 s to 0.7 s), median swT% a small increase and median staT% a small decrease. Differences were shown in swT% and staT% among the two legs: while on a leg the swT% was lower that 50% on the other was higher (difference of about 6–7%) and vice versa for the staT%. Discussion: Temporal gait parameters showed weekly changes during the first two months of independent walking in agreement with data collected less frequently and shown in literature [1]. Present results show the dominance of a leg in respect to the other in most of the toddlers, suggesting that many of them use actively and predominantly one leg to facilitate and control progression, while the other is mainly used passively (low staT%). Future studies will quantitatively analyse different gait strategies shown by toddlers during this period [1], allowing having a quantitative integrated vision of how many different aspects of gait change during this very important first phase of gait development.