Aurora Scientific 1 article published in JoVE Biology In vivo Measurement of Knee Extensor Muscle Function in Mice Camille R. Brightwell1,2, Ted G. Graber3, Benjamin D. Brightwell4,5, Matthew Borkowski6, Brian Noehren5,7, Christopher S. Fry1,2 1Department of Athletic Training and Clinical Nutrition, University of Kentucky, 2Center for Muscle Biology, University of Kentucky, 3Department of Physical Therapy, East Carolina University, 4Kinesiology and Health Promotion Graduate Program, University of Kentucky, 5Biomotion Lab, College of Health Sciences, University of Kentucky, 6Aurora Scientific, 7Department of Physical Therapy, College of Health Sciences, University of Kentucky Quantification of knee extensor maximal strength is imperative to understand functional adaptations to aging, disease, injury, and rehabilitation. We present a novel method to repeatedly measure in vivo knee extension isometric peak tetanic torque.