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.
