title: Review of Modelling Techniques for In Vivo Muscle Force Estimation in the Lower Extremities during Strength Training.
abstract: BACKGROUND
  Knowledge of the musculoskeletal loading conditions during strength training is essential for performance monitoring, injury prevention, rehabilitation, and training design. However, measuring muscle forces during exercise performance as a primary determinant of training efficacy and safety has remained challenging.
  
  
  METHODS
  In this paper we review existing computational techniques to determine muscle forces in the lower limbs during strength exercises in vivo and discuss their potential for uptake into sports training and rehabilitation.
  
  
  RESULTS
  Muscle forces during exercise performance have almost exclusively been analysed using so-called forward dynamics simulations, inverse dynamics techniques, or alternative methods. Musculoskeletal models based on forward dynamics analyses have led to considerable new insights into muscular coordination, strength, and power during dynamic ballistic movement activities, resulting in, for example, improved techniques for optimal performance of the squat jump, while quasi-static inverse dynamics optimisation and EMG-driven modelling have helped to provide an understanding of low-speed exercises.
  
  
  CONCLUSIONS
  The present review introduces the different computational techniques and outlines their advantages and disadvantages for the informed usage by nonexperts. With sufficient validation and widespread application, muscle force calculations during strength exercises in vivo are expected to provide biomechanically based evidence for clinicians and therapists to evaluate and improve training guidelines.
authors.affiliation: Institute for Biomechanics, ETH Zurich, HCI E 351, 8093 Zurich, Switzerland.
authors.forename: Florian
authors.initials: F
authors.lastname: Schellenberg
authors.affiliation: Institute for Biomechanics, ETH Zurich, HCI E 351, 8093 Zurich, Switzerland.
authors.forename: Katja
authors.initials: K
authors.lastname: Oberhofer
authors.affiliation: Institute for Biomechanics, ETH Zurich, HCI E 351, 8093 Zurich, Switzerland.
authors.forename: William R
authors.initials: WR
authors.lastname: Taylor
authors.affiliation: Institute for Biomechanics, ETH Zurich, HCI E 351, 8093 Zurich, Switzerland.
authors.forename: Silvio
authors.initials: S
authors.lastname: Lorenzetti
mesh_terms: D001265:Athletic Injuries / Q000209:etiology / Q000503:physiopathology; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D004576:Electromyography; D015444:Exercise / Q000502:physiology; D006801:Humans; D007866:Leg; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D009142:Musculoskeletal Physiological Phenomena; D055070:Resistance Training / Q000009:adverse effects; D013177:Sports / Q000502:physiology