• Bickel CS, Slade JM, Haddad F, Adams GR and Dudley GA (2003). The acute molecular responses of skeletal muscle to resistance exercise in able-bodied and spinal cord injured subjects. J Appl Physiol Summary: Spinal cord injury (SCI) results in muscle atrophy which contributes to a number of health problems such as cardiovascular deconditioning, metabolic derangement, and osteoporosis. Electromyostimulation (EMS) holds the promise of ameliorating SCI related muscle atrophy and therefore improving general health. To date, EMS training of long term SCI subjects has resulted in some muscle hypertrophy but has fallen short of normalizing muscle mass. The aim of this study was to compare the molecular responses of vastus lateralis muscles from able bodied (AB) and SCI subjects following acute bouts of EMS induced resistance exercise to determine if SCI muscles displayed some impairment in response. Analysis included mRNA markers known to be responsive to increased loading in rodent muscles. Muscles of AB and SCI subjects were subjected to EMS stimulated exercise in two 30 minute bouts separated by a 24 hour rest. Needle biopsy samples were obtained 24 hours after the second exercise bout. In both the AB and SCI muscles, significant changes were seen IGFBP4, IGFBP5, cyclin dependent kinase inhibitor p21 and myogenin mRNA levels. In AB subjects the mRNA for mechano-growth factor (MGF) was also increased. Prior to exercise, the total RNA concentration of the SCI muscles was less than that of the AB subjects but not different post-exercise. The results of this study indicate that acute bouts of resistance exercise stimulate molecular responses in the skeletal muscles of both AB and SCI subjects. The responses seen in the SCI muscles indicate that the systems which regulate these molecular responses are intact even after extended periods of muscle unloading. Department of Exercise Science, University of Georgia, Athens, GA, USA; Shepherd Center, Athens, GA, USA.