The Effects of Lower Extremity Blood Flow Restriction Training on Power, and Muscle Size.

INITIAL DATA COLLECTION (60-75 minutes) Measurements will be performed by a researcher blinded to group allocation. Height and weight will be measured with a stadiometer and calibrated scale.

Participant will sit to complete the following intake forms: Par-Q+, Numeric Pain Rating Scale, International Physical Activity Questionnaire- short form After sitting at least 5 minutes the following resting measures will be taken: resting heart rate, resting blood pressure

Thigh Circumference (supine): Markings will be made bilaterally at the lateral femoral condyle, proximal greater trochanter, and a line in an anterior to posterior direction 50% between these two landmarks. A circumferential measurement of the thigh will be taken three separate times at that 50% line for each leg.

Muscle Size: Measurements will be taken of the vastus lateralis and biceps femoris following the protocol established by Ruas et al using the GE LOGIC e, GE Healthcare, WI, USA). Superficial markings will be made to assist the researcher in locating desired anatomical location for measurement. Markings will be made bilaterally at the lateral femoral condyle, proximal aspect of greater trochanter, and a line in an anterior to posterior direction 50% between these two landmarks. Participants will lay supine for vastus lateralis and prone for biceps femoris measurement. The ultrasound transducer will be placed on the skin, utilizing a water-gel coupling agent, oriented perpendicular to the skin interface over the muscle of interest at the line that marks 50% of the distance between lateral femoral condyle and proximal greater trochanter. Images will be saved in the ultrasound device using participant identifier, muscle visualized, and date (example: BFR01_VL_05.01.19). Images will be exported to a computer for analysis using ImageJ software (National Institutes of Health, Bethesda, MD, USA).

Maximal Vo2: Oxygen consumption will be assessed on stationary rower (Concept2 Inc., Morrisville, VT) utilizing a metabolic cart and gas exchange (ParvoMedics, Provo, UT). Throughout the exercise test rating of perceived exertion (RPE) will be assessed within the final 10 seconds of each stage. Each participant will proceed throughout the various stages of the exercise test in a sequential fashion until test is terminated for one of the following reasons (1) participant requests to stop exercise test, (2) RPE reaches 10 out of 10, (3) participant fails to maintain desired Watts for that stage.

Maximal Deadlift Test:

Lower extremity strength will be assessed through an estimated one-repetition maximum (1-RM) deadlift with a dumbbell in each hand. Prior to performing the test each participant will receive instruction on proper technique for deadlift and the ability to perform practice repetitions as needed. The participant will begin with an estimated weight after consultation with research team member. The participant will grasp one dumbbell in each hand in an upright standing position and perform the maximum number of deadlifts possible. If the participant performs at least 1 repetition and no more than 9 repetitions of deadlifts they are finished with the deadlift test. If the participant performs more than 9 repetitions the resistance will be altered following the table below and the deadlift test will be performed again after 2-minute rest. Periods of testing and rest will alternate until the resistance provides at least 1 repetition but no more than 9 repetitions. The final deadlift weight and number of successful repetitions will be recorded and entered into the following equation to determine an estimated maximum deadlift resistance.

Randomization Participants will be randomly assigned to either the BFR group or the control group (CG), using block randomization. A predetermined random allocation of equal parts BFR and CG will be determined for each set of 10 participants (example: participants 1-10 will contain a random allocation of 5 to each intervention group, the same for participants 11-20 and 21-30). The block randomization will be performed by an individual not involved in this study (other than to randomize) with the result of the randomization being concealed until the after initial testing session. Both groups will participate in the same number of exercise sessions (2x per week for 4 weeks) and one final testing session.

EXERCISE SESSIONS (Study total = 4 hours) All exercise sessions will be conducted by a researcher who is not blinded to group allocation. Each group will complete two training sessions per week for four weeks. RPE will be recorded in the final seconds of each round of exercise. If participant does not complete the protocol for either rower or deadlift the resistance will be retained for future sessions. If participant reports <6/10 RPE at the final stage of either rower or deadlift the intensity for that exercise will be increased by 10% (watts or resistance respectively).

BFR Group

BFR will be conducted utilizing the Personal Tourniquet System (PTS) for BFR, Delfi Medical Innovations Inc (Vancouver , BC, Canada).

WARM-UP: Standard dynamic warm-up

BFR Set-up

• Placement of BFR sleeve and BFR cuffs around bilateral thighs.
• Participant will lay supine with cuffs in place.
• Researcher will initiate cuff inflation to measure arterial pressure
• After successful measurement of arterial pressure each cuff will be set to inflate to 80% occlusion for the exercise session.
• Participant will remain in BFR cuffs and move into the exercise session. Participants will complete a dynamic warm-up prior to starting the BFR exercise protocol. Upon completion of the protocol, the cuff will be deflated and removed. The participant will then walk for five minutes at a self-selected pace for a cool down.

Control Group

Participants will complete an identical dynamic warm-up as the BFR group prior to starting the CG exercise protocol. Upon completion of the protocol, the participant will then walk for five minutes at a self-selected pace for a cool down.

Final Testing Protocol (60-75 minutes)

Follow the same protocol as initial testing with all measurements taken by researcher blinded to group allocation. The researcher conducting final testing will not have been involved in the intervention period for any participant nor ask the participant about their experience or group allocation. Participants will also be instructed to not share their group allocation with the researcher collecting the final data.

Inclusion criteria

• Recreationally active adults (3 mo more days of moderate intensity physical activity per week, with at least some combination of aerobic and strength training).

Exclusion criteria

• Failure to achieve clearance for exercise participation via the Par-Q+ screening tool
• Currently pregnant or with 3 months post-partum
• Presence of chronic low back pain
• history of surgery to change the structure of joints within the lower extremity (joint replacement, osteotomy)
• Known blood clotting disorder or taking blood thinner medications
• Presence of peripheral vascular disease
• Presence of systemic or widespread pain disorder (fibromyalgia, chronic regional pain syndrome)
• Currently under activity limitations for any reason