Elsevier

Human Movement Science

Volume 36, August 2014, Pages 12-19
Human Movement Science

The role of excess mass in the adaptation of children’s gait

https://doi.org/10.1016/j.humov.2014.05.002Get rights and content

Highlights

  • Novel findings of an acute loading condition to explain the role of excess mass in children’s gait.

  • Obese children require larger muscle contractions to maintain similar gait patterns.

  • Incidental muscle training may occur in obese children as a result of carrying excess mass.

Abstract

The aim of this study was to determine differences in lower extremity joint powers at weight acceptance and propulsion in obese and non-obese children during two loading conditions. Gait analyses were conducted on 20 non-obese and 20 obese children (8–12 years). The first testing session was completed in a normal (unloaded) condition; an additional 10% body mass (acute loading) was added during the second session. Peak lower extremity joint power (W) phases were identified at weight acceptance and propulsion. Obese children demonstrated greater joint powers than non-obese children, at both weight acceptance and propulsion. Likewise, all children produced larger joint powers during acute loading conditions than unloaded. When body mass is a covariate, significant main effects for loading conditions remained for the hip and knee during weight acceptance and the hip and ankle at propulsion; no group differences remained significant. Obese children produced greater power generation at the hip and ankle during unloaded conditions than non-obese children during acute conditions. Only the ankle had greater power generation after accounting for body mass. The findings suggest that obese children must increase muscular contraction force to maintain normal gait function. While increased joint powers necessary for normal gait could result in incidental muscle strengthening of obese children, this persistent increase in muscular force demand could result in musculoskeletal injury.

Introduction

Weight management requires a shift from sedentary behavior to physical activity (Barlow, 2007, Kumanyika et al., 2008). However, it is well recognized that obese children are limited in their capacity to be physically active (Shultz et al., 2011, Shultz et al., 2010, Tsiros et al., 2011). Obese children are challenged when moving excess mass and tasks that require agility, power, or speed are completed with greater difficulty (Bovet et al., 2007, Brunet et al., 2007, Deforche et al., 2003). The challenges associated with executing these activities perpetuate a cycle that contributes to a more sedentary lifestyle and subsequent increase in pediatric obesity (Shultz, Deforche, et al., 2010).

Excess mass has an obvious role in the kinetic variables of gait in obese children. Increased joint moments have been seen in obese children during various activities of daily living (Strutzenberger, Richter, Schneider, Mundermann, & Schwameder, 2011), with greater emphasis placed on differences during walking (Gushue et al., 2005, McMillan et al., 2010, Nantel et al., 2006, Shultz et al., 2009). Specifically, obese children are exposed to greater lower extremity joint moments in all three cardinal planes of motion (Shultz et al., 2009). After normalizing for body mass, this population continues to generate greater peak knee extensor and hip flexor moments during late stance, when the obese child must prepare to progress mass forward (McMillan et al., 2010). Similarly, obese children generate larger lower extremity joint powers than non-obese children. When body mass is considered, the negative power phase during weight acceptance was still greater at the hip (sagittal) and knee (frontal) in obese children (Shultz, Hills, Sitler, & Hillstrom, 2010). The persistent increases in lower extremity joint moments and powers seem to occur at two important periods of the stance phase: when excess mass is being accepted and when it must be propelled forward. Statistical modeling of gait changes after weight loss suggested that improved energetic costs are a consequence of less isometric muscle contraction to support a lower body weight (Peyrot et al., 2012). The implications for the role of body mass in gait adaptation is great; however, the muscle strengthening associated with this particular weight reduction program could prove to be a confounding factor in the changes to physiologic muscle function.

No research to date has determined if the changes in gait kinetics result solely from carrying excess mass, or if gait has been adapted to handle the chronic overload to the joints. Therefore, the purpose of this study was to examine kinetic differences in gait between chronic and acute adaptation to excess mass. Specifically, lower extremity joint powers (W) in the sagittal, frontal, and transverse planes were assessed at the predetermined periods of weight acceptance and propulsion during the stance phase of gait. Comparisons between obese and non-obese children elucidated gait differences in children who are exposed to chronically excessive loads. To understand how mass acutely affects locomotion, comparisons between unloaded (i.e., body mass) and acutely loaded (i.e., body mass + 10%) conditions were made.

Section snippets

Participants

Forty children, aged 8–12 years, were recruited through print and radio press, local schools, and publicly posted advertisements. Twenty obese children (Cole, Bellizzi, Flegal, & Dietz, 2000) were matched to non-obese children of similar age and gender (55% male). Self-reported health history questionnaires were completed prior to participation; exclusion criteria included neuromusculoskeletal disease, or lower extremity condition (injury or surgery) in the previous 6 months. Participants and

Results

Mean peak power phases, standard deviations, and test statistics for group and condition are presented in Table 2.

Discussion

To our knowledge, this is the first study to examine the role of acute and chronic weight gain in the gait adaptation of children. Obese children demonstrated greater lower extremity joint powers than non-obese children, at both weight acceptance and propulsion. Likewise, all children produced larger joint powers during AC than UC. When body mass was accounted for statistically, significant differences in loading conditions remained for the hip and knee during weight acceptance and the hip and

Conclusions

The group and condition main effects underline the influence of chronic and acute loading on children’s gait. However, if it was simply the introduction of excess mass that produced kinetic differences, then there would have been the same statistical differences across condition and group. The persistent differences between conditions, but not group, suggest that there may be a training effect associated with chronic loading in obese children. By gradually increasing the load (as is seen in

Acknowledgements

This study was supported by the Institute of Health and Biomedical Innovation Early Career Researcher Scheme at Queensland University of Technology (Brisbane, Australia).

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