Biomechanical variations in children who are overweight and obese during high-impact activities: A systematic review and meta-analysis.

Youth who are obese or overweight demonstrate evidence of poor lower extremity joint health and alterations in gait characteristics compared with youth who are healthy weight. However, there is no consensus if altered movement patterns are still present during high-impact activities. The purpose of this review was to determine if spatiotemporal and kinematic and kinetic variables during high-impact activities were significantly different between youth who are overweight and obese compared with youth who are healthy weight. An electronic search of five databases was conducted, and a meta-analysis and qualitative evidence synthesis was performed to determine the level of evidence, analyzing three tasks: running, jumping, and hopping. The findings of this review include the following: (1) overweight/obese (OW/OB) had higher stance phase time during running, (2) OW/OB had decreased hip flexion angles during running and stationary running, (3) OW/OB had decreased knee flexion angles during landing phase of jumping and hopping, and (4) OW/OB had increased hip abduction moments during running and jumping. These altered kinematic and kinetic variables at the hip and knee may result in mechanical inefficiency with high-impact activities, as well as potentially increased risk of joint degradation and poor joint health into adulthood.

Moderate reliability of the lateral step down test amongst experienced and novice physical therapists.

BACKGROUND/INTRODUCTION: The lateral step-down test is used to appraise movement quality in patients with patellofemoral pain (PFP), however, it is unclear if reliability of the test is affected by physical therapist experience. OBJECTIVE: Determine if there is a difference in reliability between 'experienced' and 'novice' physical therapists appraising movement quality of patients with PFP during the lateral step-down test. METHODS: Three 'experienced' and 3 'novice' physical therapists analyzed movement quality of 22 participants [mean age (SD) 28.25 (6.5) years] with PFP. Physical therapists viewed two-dimensional videos of participants performing the lateral step-down test and appraised the quality with a score (0-1 = 'good'; 2-3 = 'fair', and 4-5 = 'poor') at baseline and 1 week. Inter- and intra-rater reliability were calculated with kappa and percent agreement. Differences between the groups were assessed with the chi-square test with an a priori alpha level of < 0.05. RESULTS: Inter- and intra-rater reliability ranged from fair to moderate (ĸ = 0.40-0.65). There was no difference in reliability between 'experienced' and 'novice' physical therapists at baseline (p = .13) or 1 week post testing (p = .94). CONCLUSIONS: There was no difference in reliability between 'experienced' and 'novice' physical therapists using categories to appraise movement quality during the lateral step-down test for patients with chronic PFP.

Obese Youth Demonstrate Altered Landing Knee Mechanics Unrelated to Lower-Extremity Peak Torque When Compared With Healthy Weight Youth.

Obese (OB) youth demonstrate altered knee mechanics and worse lower-extremity performance compared with healthy weight (HW) youth. Our objectives were to compare sagittal plane knee landing mechanics between OB and HW youth and to examine the associations of knee and hip extension peak torque with landing mechanics in OB youth. Twenty-four OB and 24 age- and sex-matched HW youth participated. Peak torque was measured and normalized to leg lean mass. Peak knee flexion angle and peak internal knee extension moment were measured during a single-leg hop landing. Paired t tests, Pearson correlation coefficients, and Bonferroni corrections were used. OB youth demonstrated worse performance and lower knee extension (OB: 12.76 [1.38], HW: 14.03 [2.08], P = .03) and hip extension (OB: 8.59 [3.13], HW: 11.10 [2.89], P = .005) peak torque. Furthermore, OB youth demonstrated lower peak knee flexion angles (OB: 48.89 [45.41 to 52.37], HW: 56.07 [52.59 to 59.55], P = .02) and knee extension moments (OB: -1.73 [-1.89 to -1.57], HW: -2.21 [-2.37 to -2.05], P = .0001) during landing compared with HW youth. Peak torque measures were not correlated with peak knee flexion angle nor internal knee extension moment during landing in either group (P > .01). OB youth demonstrated altered landing mechanics compared with HW youth. However, no associations among peak torque measurements and knee landing mechanics were present.