title: Muscle Forces and Their Contributions to Vertical and Horizontal Acceleration of the Center of Mass During Sit-to-Stand Transfer in Young, Healthy Adults.
abstract: Sit-to-stand transfer is a common task that is challenging for older adults and others with musculoskeletal impairments. Associated joint torques and muscle activations have been analyzed two-dimensionally, neglecting possible three-dimensional (3D) compensatory movements in those who struggle with sit-to-stand transfer. Furthermore, how muscles accelerate an individual up and off the chair remains unclear; such knowledge could inform rehabilitation strategies. We examined muscle forces, muscleinduced accelerations, and interlimb muscle force differences during sit-to-stand transfer in young, healthy adults. Dynamic simulations were created using a custom 3D musculoskeletal model; static optimization and induced acceleration analysis were used to determine muscle forces and their induced accelerations, respectively. The gluteus maximus generated the largest force (2009.07 ± 277.31 N) and was a main contributor to forward acceleration of the center of mass (COM) (0.62 ± 0.18 m/s(2)), while the quadriceps opposed it. The soleus was a main contributor to upward (2.56 ± 0.74 m/s(2)) and forward acceleration of the COM (0.62 ± 0.33 m/s(2)). Interlimb muscle force differences were observed, demonstrating lower limb symmetry cannot be assumed during this task, even in healthy adults. These findings establish a baseline from which deficits and compensatory strategies in relevant populations (eg, elderly, osteoarthritis) can be identified.
authors.affiliation: 1 The Ohio State University.
authors.forename: Elena J
authors.initials: EJ
authors.lastname: Caruthers
authors.affiliation: 2 Stanford University.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Thompson
authors.affiliation: 1 The Ohio State University.
authors.forename: Ajit M W
authors.initials: AM
authors.lastname: Chaudhari
authors.affiliation: 1 The Ohio State University.
authors.forename: Laura C
authors.initials: LC
authors.lastname: Schmitt
authors.affiliation: 1 The Ohio State University.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Best
authors.affiliation: 3 North Carolina State University.
authors.forename: Katherine R
authors.initials: KR
authors.lastname: Saul
authors.affiliation: 1 The Ohio State University.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Siston
mesh_terms: D000054:Acceleration; D001696:Biomechanical Phenomena; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D019415:Torque; D055815:Young Adult
keywords: OpenSim; knee; musculoskeletal modeling