resistance training and blood flow restriction

Conditions: Blood Flow Restriction and Low-Intensity Resistance Training

Summary: the primary purposes of the proposed study is 1) to examine the changes of muscle fiber cross-sectional areas in the leg extensor muscles (vastus lateralis) pre- to post- 6 weeks of high-intensity resistance training and low-intensity resistance training with blood flow restriction and 2) to examine changes in motor unit size (a non-invasive measure of muscle fiber size) in the leg extensor muscles (vastus lateralis) pre- to post- 6 weeks of high-intensity resistance training and low-intensity resistance training with blood flow restriction.

specific aims and hypotheses: specific aim 1: to examine the changes of type i and ii (different types of muscle fibers) muscle fiber cross-sectional areas in the leg extensor muscles (vastus lateralis) pre- to post- 6 weeks of high-intensity resistance training and low-intensity resistance training with blood flow restriction. hypothesis 1: type i and ii fiber cross-sectional area will increase following low-intensity resistance training with blood flow restriction, however, only cross-sectional area of type ii fibers will increase post high-intensity resistance training. specific aim 2: to examine changes in the size of the motor units that are active during low and high intensity contractions in the leg extensor muscles (vastus lateralis) pre- to post- 6 weeks of high-intensity resistance training and low-intensity resistance training with blood flow restriction. hypothesis 2: the motor units that are active during low and high intensity contractions will increase in size from low-intensity resistance training with blood flow restriction, but only the motor units that are active during high intensity contractions will increase in size from high-intensity resistance training. specific aim 3: to examine changes in whole muscle cross-sectional area as measured via ultrasound pre- to post- 6 weeks of high-intensity resistance training and low-intensity resistance training with blood flow restriction. hypothesis 3: whole muscle cross-sectional area will increase to similar degrees from both high-intensity resistance training and low-intensity resistance training with blood flow restriction.

Eligibility criteria:
inclusion criteria: - exclusion criteria: * participants must not have participated in resistance training more than 5 times in the 6 months preceding the study. * participants must be healthy and free of any cardiovascular, metabolic or musculoskeletal conditions that may affect the results of the investigation. * participants must not have a history of severe hip, knee and/or ankle injuries, or any other pathological conditions that impair their motor control. * participants must not have any pre-existing cardiovascular conditions that involve blood flow/blood clotting. * participants who are currently taking blood thinners or any medications regulating blood pressures or heart rate will not be eligible to participate in the study. * female participants who are pregnant at the start of or who are planning to become pregnant during the resistance training intervention will not be eligible to participate in the study.