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Title: Human forearm immobilisation : impact on muscle mass, function and glucose disposal
Author: Skirrow, Sarah Louise
ISNI:       0000 0004 6352 5779
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2014
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Physical inactivity is the fourth leading cause of death worldwide and has numerous health implications. Evidence suggests that physical inactivity shortens life expectancy and is causative in a number of diseases. The world’s population is becoming increasingly inactive and for this reason, research has focused upon determining the functional and metabolic adaptations induced by physical inactivity with the aim of developing effective countermeasures. Several models of physical inactivity have been developed however the majority of studies have focused upon adaptations in the lower body. In contrast, the model of physical inactivity utilised in the present study is forearm immobilisation . This novel approach creates a within subject control and therefore allows the localised effects of physical inactivity to be examined, and compared to the contralateral non-immobilised limb. This thesis describes a series of studies performed in healthy male subjects which have investigated the effects of forearm immobilisation on muscle function, blood flow and glucose disposal. The major findings were that 3 and 5 weeks forearm immobilisation resulted in a decline in hand grip strength despite no change in forearm muscle cross sectional area or volume. In addition a decline in forearm glucose uptake was observed within 7 days forearm immobilisation and occurred in the face of unchanged plasma insulin concentrations, thereby demonstrating the development of insulin resistance that was localised to the immobilised limb. Resistance exercise was used as a potential countermeasure, and an intermittent resistance exercise rehabilitation programme performed after the period of forearm immobilisation reversed the immobilisation induced deficit in hand grip strength and glucose uptake. Additionally, a similar programme performed during immobilisation was able to protect against a decline in hand grip strength but not the development of localised forearm insulin resistance . Over the course of this thesis several interventions were utilised to elucidate the mechanisms responsible for the development of immobilisation induced limb insulin resistance . Pharmacological vasodilation and pharmacological activation of the pyruvate dehydrogenase complex were unable to reverse the immobilisation induced decline in forearm glucose uptake. Overall these observations demonstrated that the development of immobilisation induced insulin resistance must reside at the intramuscular level. Therefore, the present thesis adds valuable knowledge to our understanding of the detrimental effects of physical inactivity and the mechanisms underlying the development of immobilisation induced insulin resistance.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available