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The Physiological and Genetic Factors Underpinning the Response to Muscle Damaging Exercise

Baumert, P (2019) The Physiological and Genetic Factors Underpinning the Response to Muscle Damaging Exercise. Doctoral thesis, Liverpool John Moores University.

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Abstract

It is often observed that there is a high individual variability in the response to exercise-induced muscle damage (EIMD), even when tested in a homogeneous cohort accounting for age, sex, ethnicity and physical activity. The response to EIMD is very complex as several tissues, including skeletal muscle fibres, the extra-cellular matrix (ECM), and tendon, play a potential role in the damage response. Therefore, the overall aim of this PhD thesis was to investigate the physiological and genetic factors underpinning the response to muscle damaging exercise. For that, the following objectives were (i) to comprehensively assess the physiological mechanisms and recovery pattern of neuromuscular fatigue of the hamstring muscle group following an intermittent sprint (IS) intervention; (ii) to investigate inter-individual differences in skeletal muscle repair/recovery after an artificial wounding (scratch) assay using of primary human skeletal muscle cells in vitro; (iii) to ascertain whether multiple genetic variations, which are linked to varying tissues, forming a polygenic profile could distinguish between high and low responders following muscle damage in vivo and in vitro; and (iv) to assess whether a genetic profile is linked with the response to both EIMD and chronic resistance exercise. The methodological and analytical approaches utilised in this thesis identified a number of important, novel and impactful findings. Following IS, the impaired hamstring muscle function and delayed recovery is probably caused primarily by damage to the contractile tissue, and participants with a greater force generating capacity (larger physiological cross-sectional area) of the biceps femoris long head were less susceptible to hamstring strength loss immediately after IS, providing evidence that the structure of the muscle protects it against peripheral fatigue/damage. The in vitro study showed that skeletal muscles with an increased number of stem cells of the connective tissue (fibroblasts) might have a better capacity to reorganise the complex ECM, which results in a faster muscle strength recovery after muscle damaging exercise. However, a larger number of active muscle stem cells (myoblasts) seems to be important for the latter stage of muscle regeneration. Individuals possessing a non-preferential genetic profile demonstrated increased rate of muscle damage biomarkers than individuals with a preferential genetic profile. Lastly, we calculated a second polygenic profile which was linked with both the EIMD and the chronic resistance exercise response. These polygenic profiles may be used to anticipate an individual’s response/adaptation to EIMD and to chronic resistance exercise, thus enabling resistance exercise to be prescribed on a personalised level to improve muscle health and function.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: Exercise-induced muscle damage (EIMD); Delayed onset muscle soreness (DOMS); Single nucleotide polymorphism (SNP); extracellular matrix (ECM); hamstring muscle group; biceps femoris long head; creatine kinase (CK); physiological cross-sectional area (PCSA); myoblast; fibroblast; satellite cell; single-leg hop landing (SLHL)
Subjects: R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions: Sport & Exercise Sciences
Date Deposited: 15 Mar 2019 11:50
Last Modified: 15 Mar 2019 11:50
DOI or Identification number: 10.24377/LJMU.t.00010325
Supervisors: Erskine, R, Stewart, C, Drust, B and Lake, M
URI: http://researchonline.ljmu.ac.uk/id/eprint/10325

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