Grant: Undergraduate Student Research Awards (USRA)

Project 1 involves determining the optimal resistance training intensity for improving bone outcomes in older adults. Modeling studies (animal studies) indicate that high magnitude loading is best for stimulating bone formation. We predict high intensity training will be superior to moderate-intensity training, which will be superior to light training for outcomes including bone mineral density (BMD) and geometric properties at the proximal part of the femur which predict strength of bone in bending and compression. Older adults (over 50y) who have low BMD are being randomized into three groups: light calisthenics-type training; moderate-intensity resistance training, and high-intensity resistance training for 12 months duration. Bone assessments are done by dual energy X-ray absorptiometry, located in a suite within our exercise-training facility. The training program involves "powerlifting" type exercises including deadlifts, squats, and bench press, which place unique loads on bone (i.e., high magnitude and abnormal strain distribution, thought to be optimal for stimulating bone formation). Additional outcomes include grip and leg strength, balance testing, walking velocity, and nutritional assessment. Project 2 involves comparing two non-surgical leg resistance exercise routines to reduce surgical leg muscle inhibition after anterior cruciate ligament reconstruction (ACLR) surgery. Men and women who have undergone ACLR in the last 12 weeks will complete two interventions on the non-surgical leg: a 120s isometric (static) contraction; and twelve 10s eccentric contractions (lengthened under tension). We predict the eccentric routine will better engage bilateral motor pathways and decrease inhibition during unloaded contractions of the surgical leg.