Adaptation to lengthening contraction-induced injury in mouse muscle

1 Muscle Biology Laboratory, Department of Health and Kinesiology, Texas A&M University, College Station, Texas 77843-4243; and 2 Muscle Biology Laboratory, Department of Kinesiology and Health, Georgia State University, Atlanta, Georgia 30303 Submitted 30 September 2003 ; accepted in final form 27 April 2004 Adaptations to repeated bouts of injury-inducing lengthening contractions were studied in mouse anterior crural muscles. Five bouts of 150 lengthening contractions were performed in vivo, with each bout separated by 2 wk of rest. Three primary observations were made. First, there was little, if any, attenuation in the immediate isometric torque losses after lengthening contractions at "physiological" stimulation frequencies (i.e.,