Sam O. Shepherd
YOU?
Author Swipe
Unintentional Underfuelling and Protein Prioritisation: A Multi-Methods Exploration of Nutrition Practices and Behaviours in Female Endurance Athletes Open
Background/Objectives: Despite increasing awareness of best sports nutrition practices, discrepancies persist between knowledge and behaviour amongst female endurance athletes. Methods: To understand this discrepancy study investigated die…
Endocrine, Metabolic, and Skeletal Muscle Proteomic Responses During Energy Deficit With Concomitant Aerobic Exercise in Humans Open
Energy deficit is a potent physiological stressor that has shaped human evolution and can improve lifespan and healthspan in a wide range of species. Preserving locomotive capacity was likely essential for survival during the human hunter‐…
Skeletal muscle proteomic responses to energy deficit with concomitant aerobic exercise in humans Open
Energy deficit is a potent physiological stressor that has shaped human evolution and can improve lifespan and healthspan in a wide range of species. Preserving locomotive capacity was likely essential for survival during the human hunter-…
Turnover rates of human muscle proteins in vivo reported in fractional, mole and absolute units Open
Background Protein fractional turnover rates (FTR) represent measurements of flux through a protein pool, i.e., net abundance (ABD) of the protein. However, if protein abundance is not measured or varies between experimental conditions, th…
Increased contact between lipid droplets and mitochondria in skeletal muscles of male elite endurance athletes Open
Endurance athletes exhibit higher skeletal muscle mitochondrial and lipid droplet (LD) content compared to recreationally active individuals, along with greater whole-body oxygen uptake and maximal fat oxidation rates. In this study, we in…
Effect of self-paced sprint interval training and low-volume HIIT on cardiorespiratory fitness: the role of heart rate and power output Open
Aim The primary aim was to assess the efficacy of self-paced sprint interval training (SIT) with low-volume high-intensity interval training (LV-HIIT) when performed without encouragement on improving cardiorespiratory fitness (CRF). A sec…
Product separability for special cube complexes Open
We prove that if a group $G$ admits a virtually special action on a CAT(0) cube complex, then any product of convex-cocompact subgroups of $G$ is separable. Previously, this was only known for products of three subgroups, or in the case wh…
A free-living, walking-based, exercise programme, with exercise timed relative to breakfast, to improve metabolic health in people living with overweight and obesity: A feasibility study Open
Optimising the timing of food intake relative to exercise may maximise the effectiveness of free-living exercise programmes on improvements in glycaemic control and cardio-metabolic health. This study aimed to assess the feasibility of a f…
GLUT4 localisation with the plasma membrane is unaffected by an increase in plasma free fatty acid availability Open
Background Insulin-stimulated glucose uptake into skeletal muscle occurs via translocation of GLUT4 from intracellular storage vesicles to the plasma membrane. Elevated free fatty acid (FFA) availability via a lipid infusion reduces glucos…
Turnover rates of human muscle proteins in vivo reported in fractional, mole and absolute units Open
Protein fractional turnover rates (FTR) represent measurements of flux through a protein pool, i.e. net abundance (ABD) of the protein. If protein abundance is not measured or is different between experimental conditions the interpretation…
People with obesity exhibit losses in muscle proteostasis that are partly improved by exercise training Open
This pilot experiment examines if a loss in muscle proteostasis occurs in people with obesity and whether endurance exercise positively influences either the abundance profile or turnover rate of proteins in this population. Men with ( n =…
Separability properties of higher-rank GBS groups Open
A rank $n$ generalized Baumslag-Solitar group is a group that splits as a finite graph of groups such that all vertex and edge groups are isomorphic to $\mathbb{Z}^n$. In this paper we classify these groups in terms of their separability p…
View article: Splittings of One-Ended Groups with One-Ended Halfspaces
Splittings of One-Ended Groups with One-Ended Halfspaces Open
We introduce the notion of halfspaces associated to a group splitting, and investigate the relationship between the coarse geometry of the halfspaces and the coarse geometry of the group. Roughly speaking, the halfspaces of a group splitti…
Muscle of obese insulin-resistant humans exhibits losses in proteostasis and attenuated proteome dynamics that are improved by exercise training Open
We examined muscle proteostasis in obese insulin-resistant (OIR) individuals to determine whether endurance exercise could positively influence proteome dynamics in this population. Male OIR (n = 3) and lean, healthy controls (LHC; n = 4) …
Graphically discrete groups and rigidity Open
We introduce the notion of graphical discreteness to group theory. A finitely generated group is graphically discrete if whenever it acts geometrically on a locally finite graph, the automorphism group of the graph is compact-by-discrete. …
Two generalisations of Leighton’s theorem (with an appendix by Giles Gardam and Daniel J. Woodhouse) Open
Leighton’s graph covering theorem says that two finite graphs with a common cover have a common finite cover. We present a new proof of this using groupoids, and use this as a model to prove two generalisations of the theorem. The first ge…
Imitator homomorphisms for special cube complexes Open
Central to the theory of special cube complexes is Haglund and Wise's construction of the canonical completion and retraction, which enables one to build finite covers of special cube complexes in a highly controlled manner. In this paper …
A cubulation with no factor system Open
The primary method for showing that a given cubulated group is hierarchically hyperbolic is by constructing a factor system on the cube complex. In this paper we show that such a construction is not always possible, namely we construct a c…
Leighton’s theorem : Extensions, limitations and quasitrees Open
Leighton's Theorem states that if there is a tree $T$ that covers two finite\ngraphs $G_1$ and $G_2$, then there is a finite graph $\\hat G$ that is covered\nby $T$ and covers both $G_1$ and $G_2$. We prove that this result does not\nexten…
Semistability of cubulated groups Open
We prove that all cubulated groups are semistable at infinity. In doing so we prove two further results about cubulations of groups. The first of these states that any one-ended cubulated group has a cubulation for which all halfspaces are…
View article: Polygenic mechanisms underpinning the response to exercise‐induced muscle damage in humans: In vivo and in vitro evidence
Polygenic mechanisms underpinning the response to exercise‐induced muscle damage in humans: In vivo and in vitro evidence Open
We investigated whether 20 candidate single nucleotide polymorphisms (SNPs) were associated with in vivo exercise‐induced muscle damage (EIMD), and with an in vitro skeletal muscle stem cell wound healing assay. Sixty‐five young, untrained…
Commensurability of lattices in right-angled buildings Open
Let $Γ$ be a graph product of finite groups, with finite underlying graph, and let $Δ$ be the associated right-angled building. We prove that a uniform lattice $Λ$ in the cubical automorphism group Aut$(Δ)$ is weakly commensurable to $Γ$ i…
Home-Based HIIT and Traditional MICT Prescriptions Improve Cardiorespiratory Fitness to a Similar Extent Within an Exercise Referral Scheme for At-Risk Individuals Open
Exercise referral schemes (ERS) are used to promote physical activity within primary care. Traditionally, ERS are conducted in a gym or leisure-center setting, with exercise prescriptions based on moderate-intensity continuous training (MI…
Evidence-based vs. social media based high-intensity interval training protocols: Physiological and perceptual responses Open
Objective High intensity interval training (HIIT) is a time-efficient exercise modality to improve cardiorespiratory fitness, and has recently been popularised by social media influencers. However, little is known regarding acute physiolog…
Agol's theorem on hyperbolic cubulations Open
Agol proved that hyperbolic cubulated groups are virtually special. The aim of these notes is to make the proof accessible to a wider audience; we retain the underlying ideas and constructions of Agol, but substantially change or add to ma…
Carbohydrate improves exercise capacity but does not affect subcellular lipid droplet morphology, AMPK and p53 signalling in human skeletal muscle Open
Key points Muscle glycogen and intramuscular triglycerides (IMTG, stored in lipid droplets) are important energy substrates during prolonged exercise. Exercise‐induced changes in lipid droplet (LD) morphology (i.e. LD size and number) have…
The Comparative Methylome and Transcriptome After Change of Direction Compared to Straight Line Running Exercise in Human Skeletal Muscle Open
The methylome and transcriptome signatures following exercise that are physiologically and metabolically relevant to sporting contexts such as team sports or health prescription scenarios (e.g., high intensity interval training/HIIT) has n…