THE UNIVERSITY OF HULL THE EFFECTS OF WEIGHT LOSS ON THE BIOMECHANICS OF WALKING GAIT IN HEALTHY OVERWEIGHT AND OBESE ADULTS: A SYSTEMATIC REVIEW being a Thesis submitted for the Degree of MSc in the University of Hull by Lisa Vinodbhai Patel BSc (Hons) Sports Technology, University of Bath, MSc Sports Biomechanics, Liverpool John Moores University December 2014 Abstract Obesity is an increasing problem in the developed world with a negative impact on health and quality of life. Weight loss interventions (both lifestyle and surgical therapies) are used as a treatment for clinical obesity and comorbidities. Obesity has been shown to adversely affect the activities of normal daily living, including walking gait and musculoskeletal function. However due to the excess fat mass of obese individuals it is difficult to measure biomechanical effects on gait. The aim of this systematic review was to determine the effects of different weight loss interventions (dietary energy restriction, physical activity/exercise and surgery interventions) on the biomechanics of gait in healthy overweight and clinically obese adults. Six electronic databases were searched for relevant journal articles. Published studies were screened for eligibility according to the predetermined inclusion and exclusion criteria. Seventeen relevant publications were selected for inclusion in the systematic review. Twelve studies used surgery as a weight loss intervention; with two of these including additional exercise after surgery. Five studies used diet and/or exercise as the weight loss intervention; with one using exercise only, one using dietary restriction only, three using combined dietary and exercise/physical activity interventions. The intervention durations ranged from 3-weeks to 48-months, with the surgery interventions typically having longer follow-up. Nine studies compared the participants’ baseline measurements to their post intervention measurements. Four studies were randomised controlled trials comparing the weight loss i intervention to a control group. Two studies were non-randomised controlled trials, where the experimental group were undergoing surgery and were compared to a control group. Eleven studies measured gait through functional walking tests which were used to measure gait (walking) velocity. Four studies incorporated more detailed gait analysis outcome measures; including temporal-spatial parameters, with three of these studies also reporting kinematic and kinetic outcome measures. Participants in all studies lost body mass after the dietary restriction, exercise and surgery interventions. Baseline mean body mass index (BMI) ranged from 30.6 ± 3.8 to 51.1 ± 9.2 kg/m2 with significant body mass reductions evident in all studies (post intervention BMI ranged from 28.2 ± 8.1 to 40.4 kg/m2). Gait velocity improved after weight loss from the separate dietary restriction, exercise training and surgery interventions. Nine studies measured gait through functional walking tests. The improvement in gait velocity ranged from 0.02 – 0.43 m/s. Overall, more improvement was evident within two surgical intervention (0.05 – 0.15 m/s) studies compared to two studies evaluating diet and exercise intervention (0.05 – 0.08 m/s) with direct gait velocity measures. There has been limited research on gait kinematics and kinetics after weight loss. As a result, there was limited overlap in measurement outcomes in the two studies undertaking 3D gait analysis following weight loss surgery which made it difficult to compare the results of the outcome measures. Further research is required on how weight loss affects the walking gait of obese individuals, especially after dietary and exercise interventions. From the published ii research, weight loss interventions have significant benefits for the improvement of gait temporal-spatial parameters and to reduce the risk of developing further musculoskeletal disorders. The limited 3D gait analysis available suggests that there is an improvement in gait function following weight loss. iii Table of Contents Abstract ................................................................................................................................................. i List of Tables ..................................................................................................................................... vii List of Figures ................................................................................................................................... viii Acknowledgements ............................................................................................................................. ix 1. Introduction ..................................................................................................................................1 2. Literature Review .........................................................................................................................4 2.1 Classification of Obesity ................................................................................................................4 2.1.1 Body Mass Index ....................................................................................................................4 2.1.2 Body Shape .............................................................................................................................4 2.1.3 Measuring Body Fat ................................................................................................................5 2.1.4 Classification of Obesity Summary ........................................................................................6 2.2 Characterisation of Obesity ............................................................................................................6 2.2.1 Centre of Mass ........................................................................................................................6 2.2.2 Muscle Strength ......................................................................................................................7 2.2.3 Energy Expenditure ................................................................................................................8 2.2.4 Characterisation of Obesity Summary ....................................................................................9 2.3 Weight Loss ...................................................................................................................................9 2.3.1 Dietary Intervention ................................................................................................................9 2.3.2 Exercise ................................................................................................................................ 10 2.3.3 Dietary Intervention and Exercise ........................................................................................ 10 2.3.4 Bariatric Surgery .................................................................................................................. 12 2.3.5 Bariatric Surgery and Exercise ............................................................................................ 13 2.3.6 Weight Loss Summary ......................................................................................................... 13 2.4 Effects of Obesity on Gait ........................................................................................................... 14 2.4.1 Temporal-Spatial Parameters ............................................................................................... 14 iv 2.4.1.1 Six Minute Walk Test (6MWT) – Distance Walked and Walking Velocity ................ 14 2.4.1.2 Effects of Slower Walking Velocity ............................................................................. 15 2.4.1.3 Stance and Swing Duration ........................................................................................... 16 2.4.1.4 Base of Support and Stance Width................................................................................ 17 2.4.2 Kinematics ........................................................................................................................... 18 2.4.2.1 Range of Motion ........................................................................................................... 18 2.4.2.2 Angular Displacement – Sagittal Plane ......................................................................... 19 2.4.2.3 Angular Displacement – Frontal Plane ......................................................................... 21 2.4.2.4 Angular Displacement – Transverse Plane ................................................................... 22 2.4.2.5 Kinematic Summary ..................................................................................................... 22 2.4.3 Kinetics ................................................................................................................................ 22 2.4.3.1 Ground Reaction Forces (GRF) .................................................................................... 23 2.4.3.2 Moments ....................................................................................................................... 24 2.4.3.3 Moments during Incline Walking ................................................................................. 27 2.4.3.4 Angular Impulse ............................................................................................................ 27 2.4.3.5 Power and Work...........................................................................................................