blood flow restriction training

Question 1

what is BFR training?

Answer 1

A patient engages in low intensity, high repetition resistance training, while wearing a tourniquet around the proximal part of their UE or LE in order to create a hypoxic environment

Question 2

what are the physiological mechanisms behind BRFT?

Answer 2

Mechanical tension model- size principle
‘Metabolite theory’ - hypoxic environment
(shift to anaerobic metabolism)
– Lactate production
– Muscle activation
– Growth hormone (GH)
– IGF-1 and satellite cells
– Myostatin
– Mammalian Target of Rapamycin
Complex 1 (mTORC1)

Question 3

how does lactate contribute to increased muscle activation?

Answer 3

Anaerobic glycolysis
-Glucose -> pyruvate -> lactate
-BFRT results in a subsequent increase in lactate- Exercise + tourniquet is necessary
Lactate and hydrogen ions drive muscle activation
-Stimulates group III and IV afferents- Inhibit alpha motor neurons → increased motor unit
recruitment to combat failure
-Motor unit firing is affected by: force, speed of contraction, and
oxygen availability

Question 4

describe growth hormone

Answer 4

● Augmented by hydrogen ion and lactate accumulation
○ Group III-IV afferents stimulate pituitary gland→ GH is released
● GH does NOT = muscle hypertrophy
○ GH aids in collagen synthesis after exercise
● BFRT was shown sig. increases in GH from baseline
○ 1.7x higher than HIT group
● Indirectly related to rest periods

Question 5

describe growth hormone

Answer 5

● Augmented by hydrogen ion and lactate accumulation
○ Group III-IV afferents stimulate pituitary gland→ GH is released
● GH does NOT = muscle hypertrophy
○ GH aids in collagen synthesis after exercise
● BFRT was shown sig. increases in GH from baseline
○ 1.7x higher than HIT group
● Indirectly related to rest periods

Question 6

describe IGF-1 and satellite cells

Answer 6

● IGF-1 is stimulated by GH and has a hypertrophic role
○ IGF-1 is not responsible for protein accretion
● Role is to fuse satellite cells into existing muscle fibers
○ Satellite cells then differentiate into myocytes
● Hypertrophy is possible through many pathways:
○ Mechanical tension
○ Metabolite accumulation

Question 7

what is the downregulation of myostatin?

Answer 7

Blocks myogenesis
For our patients, we want to downregulate this protein: allow myogenic cells to proliferate→ muscle hypertrophy

Question 8

what is mammalian target of rapamycin complex 1 (mTORC1)?

Answer 8

● Pathway responsible for muscle protein synthesis (MPS)
○ Switch to turn on/off cell growth
● mTORC1 activation directly related to number of motor units recruited
○ If enough protein is available, MPS is augmented
○ BFRT activates the mTORC1 pathway
● Important to consume adequate amount of protein after BFRT