Blood flow restriction exercise during microgravity exposure in parabolic flight.

This case report evaluates whether it is possible to perform blood flow restriction (BFR) exercise during exposure to microgravity. The objectives were three-fold: (1) to determine if a personalised tourniquet system (PTS) hardware technology performs nominally and enables BFR exercise in microgravity; (2) to determine if BFR augments the exercise stimulus in microgravity in a similar manner to its application on Earth; and (3) to evaluate tolerance and acceptability of performing BFR exercise and operating the PTS hardware in microgravity. Two participants performed resistance squat and deadlift exercises on a flywheel device (inertia of 0.01 kg m²) with and without BFR during microgravity in parabolic flight onboard the National Research Council's Falcon 20 aircraft. Heart rate, perceived exertion and discomfort, and the participants' tolerance and acceptability of performing BFR exercise in microgravity compared to exercise without BFR were measured. Performance of the PTS hardware technology was also evaluated. This case report demonstrates, for the first time, that it is possible to perform BFR exercise in microgravity in a manner that may augment the physiological stress of exercise in an acceptable and tolerable fashion. Importantly, the BFR hardware technology required to perform BFR exercise in an accurate, safe and effective manner performs nominally in microgravity. Future research should aim to conduct investigations during longer exposures to microgravity (i.e. during 3- to 6-month missions on the International Space Station), providing a more comprehensive evaluation of the physiological stimulus provided and the tolerance and acceptability when performing BFR exercise in the space environment.