Kyle J Hackney, Meghan Everett, Jessica M Scott and Lori Ploutz-Snyder wrote a paper on Blood Flow-restricted Exercise In Space that was published in the Journal of Extreme Physiology & Medicine in 2012.
The electronic version of this article is online here.
It is known that prolonged exposure to microgravity in space results in chronic physiological adaptations including skeletal muscle atrophy, cardiovascular deconditioning, and bone demineralization. To attenuate the negative consequences of weightlessness during spaceflight missions, crew members perform moderate- to high-load resistance exercise in conjunction with aerobic (cycle and treadmill) exercise.
Recent evidence from ground-based studies suggests that low-load blood flow-restricted (BFR) resistance exercise training can increase skeletal muscle size, strength, and endurance when performed in a variety of ambulatory populations. This training methodology couples a remarkably low exercise training load (approximately 20%–50% one repetition maximum (1RM)) with an inflated external cuff (width, ranging between approximately 30–90 mm; pressure, ranging between approximately 100–250 mmHg) that is placed around the exercising limb. BFR aerobic (walking and cycling) exercise training methods have also recently emerged in an attempt to enhance cardiovascular endurance and functional task performance while incorporating minimal exercise intensity. Although both forms of BFR exercise training have direct implications for individuals with sarcopenia and dynapenia, the application of BFR exercise training during exposure to microgravity to prevent deconditioning remains controversial.
The aim of this review by Hackney et al. is to present an overview of BFR exercise training and discuss the potential usefulness of this method as an adjunct exercise countermeasure during prolonged spaceflight.
We believe this paper presents a comprehensive review of published articles on BFR and includes excellent tables that compare various references. However, certified KAATSU Specialists understand there are some very important things to keep in mind when reading this article:
* The authors have never seen or done KAATSU.
* Achieving muscular failure or technical failure is essential to following KAATSU the original BFR principles and protocols and is not noted.
* The combination of base pressure and optimal pressure is also a critical element of KAATSU protocols. In the article, only one form of pressure is reported. KAATSU Specialists know that both pressures (i.e., Base SKU and Optimal SKU) of their clients and patients is important to identify and utilize.
* KAATSU Air Band width and placement are very important. KAATSU arm bands are 30-33mm and KAATSU leg bands are 50-53mm. The authors only describe one width and some of the widths are not standard KAATSU widths.
* KAATSU Specialists understand the net result of the systemic effect due to KAATSU. The authors do not mention that other muscles proximal to the bands (e.g. core or contra-lateral muscle) also benefits from KAATSU.
* There is no description of the mechanism of how KAATSU modifies blood flow or about obstruction of venous outflow which leads to backing up and congesting the distal extremity.
* There is no description about how muscle contraction itself restores circulation by squeezing venous blood past the KAATSU Air Band.
KAATSU users generically define KAATSU as the original BFR (blood flow restriction).
The nuance of defining KAATSU as Blood Flow Restriction Training (or the commonly used terms such as Occlusion Training or Tourniquet Training) is important.
KAATSU is a means to moderate blood flow both in and out of the limbs. This is why the KAATSU Cycle is so important. This is also why the Base SKU (i.e., manual tightening of the KAATSU Air Bands) in combination with Optimal SKU (i.e., inflation of the KAATSU Air Bands) is so important in setting the pressures to achieve maximum benefits from KAATSU. The term “restriction” only implies that blood is reduced or restricted going OUT of the limb. The term “occlusion” implies that the blood flow is reduced and restricted going IN the limb.
However, the interaction of the blood flow both in and out of the limb during the KAATSU Cycle and KAATSU Training is vitally important to realize the full benefits of KAATSU.