The Impact of Exercise With Blood Flow Restriction: Sex and Age Differences

Previous studies indicated a reduced workload (i.e., lifting lighter weight) combined with blood flow restriction leads to increased fat-free mass and muscle strength. However, females have been underrepresented in the blood flow restriction literature. Therefore, no study has investigated whether males and females of different age groups have different adaptations in fat-free mass, muscle strength, and performance outcomes following resistance training using blood flow restriction.

The primary objective will be to investigate sex differences in fat-free mass following six weeks of resistance training combined with blood flow restriction in young and older adults.

The secondary objective is to investigate sex differences in muscle strength, physical performance, and blood biomarkers between males and females following resistance training and blood flow restriction.

Briefly, participants between 19-30 years and 65 years and older will be recruited to participate in this study. Participants will present to the laboratory for two baseline testing visits interspersed with a minimum of four days. The first testing visit will include a variety of questionnaires, a blood draw, lipid and glucose, a dual-energy x-ray absorptiometry scan, anthropometrics, and a submaximal VO2. The second visit will include several physical function tests, such as the short physical performance battery and the Y-balance test, as well as a high-intensity isokinetic fatigue test using isokinetic dynamometry and 1-repetition maximum testing.

Upon completion of baseline testing, participants are enrolled in the exercise program. The first exercise session includes a blood draw before and immediately after the training session. This procedure will be duplicated at the final exercise session at the end of the six weeks.

Participants' full occlusion will be estimated using the formula developed by Loenneke et al. (2015). Then each participant's occlusion will be set at 60% of each individual's total limb occlusion. This will be used in combination with the following exercises incline chest press, seated row, leg press, knee extension, and knee flexion performed at 30% of 1RM. The protocol is as follows: 30 repetitions followed by three sets of 15 repetitions for a total of four sets and 75 repetitions per exercise. There will be a one-minute recovery between sets where the cuffs remain inflated and a four-minute recovery between exercises where the cuffs will be deflated.

Following the completion of the six weeks of exercise, participants will again present to the laboratory for two follow-up visits similar to the first two baseline visits.

Inclusion criteria

• Between the ages of 19 and 100 years
• Sedentary (not meeting physical activity guidelines), but otherwise healthy

Exclusion criteria

• Aged outside the threshold
• Uncontrolled hypertension
• Presence of cardiovascular disease
• Either surgery, bone fracture, or skin graft within the previous three months
• Uncontrolled diabetes mellitus
• Pregnancy
• Individuals taking medications known to increase risk of blood clotting