A significant portion of the American population currently lives with a disability. There are about 300,000 Americans living with a spinal cord injury (SCI) with approximately 18,000 new cases each year. Cerebrovascular accidents (CVA), or strokes, occur at 795,000 new cases per year in the USA with strokes being the third-leading cause of death and disability combined in the world3. There are about 750,000 US adults living with multiple sclerosis (MS), 30,000 US adults with ALS, about 1400 Americans are born each year with spina bifida, about 11,000 Americans are born each year with cerebral palsy, and there were 1.6 million American amputees as of 2005, with that number expected to double by 2050. These disabilities tend to reduce the activity levels of these individuals, which puts them at an increased risk of developing comorbidities such as obesity, insulin resistance, dyslipidemia, and more. These comorbidities are often already present in those who have had a CVA, and those who are older experience an even greater burden than those who are younger. Thus, exercise regimens are crucial to maintaining their health.

Aging is associated with an increase in susceptibility to injury and a decrease in functional ability related to a decrease in muscle size and strength. This age-related decrease is also known as primary sarcopenia. Resistance exercise, such as weightlifting, has been shown to improve muscle size and strength and functional ability in elderly individuals, and resistance exercise is widely regarded as the best method to slow the progression of primary sarcopenia. Resistance exercise and physical activity has also been shown to reduce the odds of developing sarcopenia later in life, suggesting an impetus for beginning an exercise regimen while young, though any age will benefit.

Blood flow restriction (BFR) training is a method of exercise that involves restricting the participant's blood flow to the target muscle group during exercise. Historically, training to increase muscle thickness and strength occurs at 70% of a person's 1 repetition maximum (1RM), which is the maximum weight someone can lift in one repetition (rep) of a given exercise. For example, if someone's 1RM for barbell biceps curl is 100lbs, he could train at 70lbs for 3 sets of 8-12 to increase his biceps curl 1RM and the size of his biceps. This training is hereto referred as high intensity resistance training (HLRT). Training at 30-50% 1RM with BFR, hereto referred as low load blood flow restriction training (LLBFR), increases muscle thickness similar to training at 50-80% 1RM without BFR. This also results in an increase in strength due to the increase in overall muscle mass. LLBFR training regimens also display greater increases in muscle size and strength when compared to identical exercise regimens but without BFR. So, training barbell biceps curl at 30-50lbs with blood flow restriction will increase biceps size similarly to our HLRT example. It will increase biceps strength too, but likely not to the same degree as our HLRT example. However, the increase in biceps strength and size in this LLBFR example will be greater than if this person trained at 30-50lbs but without BFR. Thus, LLBFR can induce similar benefits to traditional HLRT but with a much lighter load.

Due to the efficacy and efficiency of LLBFR in increasing muscle size and strength, it has been proposed as an alternate exercise regimen for those unable to tolerate, or are contraindicated for, traditional HLRT, such as the elderly or individuals with disabilities. This study proposes to examine if LLBFR is beneficial when compared to traditional low load resistance training.