Fortis, H (2023) Exploring intramuscular energy storage. Implications for health and exercise performance. Masters thesis, Liverpool John Moores University.

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Abstract

Chapter 1 of this thesis focuses on the role of skeletal muscle on carbohydrate storage and glucose control. Responsible for ~80% of the body’s carbohydrate stores and a modest, yet important quantity of fat, skeletal muscle is a crucial site for energy storage in the human body. As skeletal muscle has large plasticity and has a finite storage capacity, it is important for energy to be stored efficiently, in order to supply metabolic processes. Lifestyle factors such as physical activity and energy intake can cause skeletal muscle to structurally adapt which can influence its metabolism. This is noticeable when comparing polarizing populations, such as trained individuals who undergo large volumes of exercise activity, compared to individuals with metabolic disorders, including type 2 diabetes (T2D). Chapter 2 of this thesis focuses on how nutritional stimuli can affect the ability of skeletal muscle to store energy and discuss the subsequent effects that this can have on exercise performance. An emerging area of exercise and health nutrition is polyphenols, a naturally occurring compound, found in many fruits and vegetables. New Zealand blackcurrant (NZBC) extract is highly concentrated in polyphenols and has been purported to aid exercise performance through improve blood flow and glucose uptake into muscle. We provide evidence that short-term supplementation of NZBC can improve carbohydrate storage in skeletal muscle. Chapter 3 then considered the differences between energy storage between individuals who are healthy, compared to those with T2D. To do this, we employed immunofluorescence microscopy to examine proteins involved in carbohydrate and lipid metabolism in skeletal muscle of individuals with T2D and healthy participants. SNAP23 is a membrane associated protein, which appears particularly important in attaching the glucose transporter (GLUT4) to the plasma membrane, therefore allowing for glucose uptake. SNAP23 is also localised on lipid droplet (LD) membranes and accumulation of intramuscular triglycerides, appear to cause lipid droplets (LD) to fuse together and grow. SNAP23 does not appear to be synthesised, therefore in order for LD to fuse it must ‘hijack’ SNAP23 away from the plasma membrane, which could attenuate glucose uptake. This chapter provides evidence for SNAP23 to be less colocalised at the plasma membrane in individuals with T2D, compared to lean individuals. However, this was not in conjunction with greater colocalisation of SNAP23 with LD. Therefore, this chapter also includes our speculation behind these unexpected findings.

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	Exercise Physiology; Physiology; Metabolism; Exercise Metabolism; Muscle metabolism; Nutrition; Exercise Nutrition; Health nutrition; Supplements; Sports supplements; Ergogenic aids; Insulin resistance; Insulin signalling; Type 2 diabetes
Subjects:	R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions:	Sport & Exercise Sciences
SWORD Depositor:	A Symplectic
Date Deposited:	13 Mar 2023 14:46
Last Modified:	13 Mar 2023 14:51
DOI or ID number:	10.24377/LJMU.t.00019048
Supervisors:	Strauss, J and Shepherd, S
URI:	https://researchonline.ljmu.ac.uk/id/eprint/19048

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