BIOMECHANICAL MODEL FOR KINETIC AND KINEMATIC DESCRIPTION OF GAIT DURING SECOND TRIMESTER OF PREGNANCY TO STUDY THE EFFECTS OF BIOMECHANICAL LOAD ON THE MUSCULOSKELETAL SYSTEM LILIANA AGUIAR * ,‡ , RITA SANTOS-ROCHA * ,† , MARCO BRANCO † , FILOMENA VIEIRA * and ANTÓNIO VELOSO * * Laboratory of Biomechanics and Functional Morphology Neuromechanics Research Group of Human Movement, CIPER Faculty of Human Kinetics, Technical University of Lisbon, Portugal † Sport Sciences School of Rio Maior Polytechnic Institute of Santar em, Portugal ‡ lsofiaaguiar@gmail.com Received 30 May 2012 Revised 23 July 2012 Accepted 25 July 2013 Published Walking is daily physical activity and a common way of exercise during pregnancy, but morphological changes can modify the gait pattern. Biomechanical models can help in evalu- ating joint mechanical loads and kinetics and kinematics during gait, and provide patterns. This study aimed to describe the gait pattern during the second trimester of pregnancy and give an orientation for biomechanical modeling for pregnant women. The ankle and hip joints seem to be more overloaded, mainly in the sagittal and frontal planes, respectively. Results showthat pregnant women have a similar walking pattern to the normal gait. This model construction was revealed to be appropriate for describing gait during the second trimester of pregnancy. Keywords: Modeling; gait; pregnancy; kinematics; kinetics. 1. Introduction Locomotor system models are an increasingly common way of studying human gait, and a variety have been developed to perform specific functions 1,2 and specific conditions. The human body is able to adjust to different conditions, changing the gait pattern. Muscle function may be reorganized to provide body acceleration and therefore modify the gait pattern, which contribute to an overload on the muscu- loskeletal system, causing pain in lower back, hip, and leg. 3 ‡ Corresponding author. June 21, 2013 7:20:41pm WSPC/170-JMMB 1450004 ISSN: 0219-5194 Page Proof 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 Journal of Mechanics in Medicine and Biology Vol. 14, No. 1 (2014) 1450004 (16 pages) ° c World Scientific Publishing Company DOI: 10.1142/S0219519414500043 1450004-1