Effect of an inverted seated position with upper arm blood flow restriction on neuromuscular fatigue

Abstract

Change in body position, in addition to disturbances to the homeostasis of our body, can exacerbate neuromuscular fatigue. Experiencing a voluntary or involuntary inverted position is a stressful condition and can alter sympathetic nervous system activity, which has been suggested as a primary mechanism that may inhibit neuromuscular and cardiovascular function. Moreover, there is a possibility of complete or partial blood flow due to limb compression during life-threatening conditions such as overturned vehicles. Blood flow restriction (BFR) due to a decrease in perfusion to a target muscle, moderate to high intensity muscle contractions, and BFR (partial occlusion during a contraction with low intensity) can lead to force reductions and dependency on type II fibres. This shift to an anaerobic phase yields metabolic by-products accumulation, stimulating muscle fibres afferents with small diameters (group III and IV). The increases in peripheral inputs to the central level may cause inhibition of final motor output, fatigue-induced greater perceived pain and effort, and increased cardiovascular stress. In view of many interacting systems during inversion, the purpose of this thesis was to explore how BFR of the upper arm while participants were securely inverted can influence isometric force production, muscle activity, fatigue, perceived pain, and cardiovascular responses. Understanding the possible mechanisms can be used by safety and survival centers during limited time rescue missions.