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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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| High-Intensity Resistance Training Group | Experimental | Participants in this group will complete 3 resistance training sessions per week for 6 weeks (18 sessions total). During each resistance training session, participants will perform 3 sets of bilateral leg-extensions (performed with both legs) to volitional failure (likely 8-12 repetitions) using 80% of their 1-repetition maximum (the most weight they are able to perform 1 complete repetition with, but not 2). |
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| Low-Intensity Resistance Training with Blood Flow Restriction Group | Experimental | Participants in this group will complete 3 resistance training sessions per week for 6 weeks (18 sessions total). During each training session, participants will perform 3 sets of bilateral leg-extensions (performed with both legs) to volitional failure using 30% of their 1-repetition maximum (the most weight they are able to perform 1 complete repetition with, but not 2). Participants in this group will perform all leg extensions with blood flow restriction cuffs applied to the proximal thigh of both legs. The pressure that the cuffs are inflated to will be calculated based on estimates of each subject's arterial occlusion pressure from their thigh circumference. Once the target pressure is reached, the cuffs will not be deflated until after the final set of the training session. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Blood Flow Restriction Cuffs | Device | This intervention consists of inflatable cuffs that are designed to partially occlude veinous blood return from the lower extremities during resistance training. |
| Measure | Description | Time Frame |
|---|---|---|
| Determine changes in muscle fiber cross-sectional area | A primary purpose of the study is 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 | July 2021-May 2022 |
| Determine changes in motor unit size | Another primary purpose of the study is 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 | July 2021- May 2022 |
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Inclusion Criteria:
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Exclusion Criteria:
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Robinson Center | Lawrence | Kansas | 66045 | United States |
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| Low-Intensity Resistance Training | Other | This intervention consists of performing low-intensity bilateral (both legs at the same time) leg extensions using 30% of a participants 1 repetition maximum (the maximum weight an individual can complete 1 repetition with, but not 2) to volitional failure. |
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| High-Intensity Resistance Training | Other | This intervention consists of performing high-intensity bilateral (both legs at the same time) leg extensions using 80% of a participants 1 repetition maximum (the maximum weight an individual can complete 1 repetition with, but not 2) to volitional failure. |
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