Browsing by Author "Lomiwes D"

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    An experimental model of contusion injury in humans
    (Public Library of Science, 17/11/2022) Barnes M; Lomiwes D; Parry DAD; Stephen M
    Introduction Contusion injuries are common in sport, but our knowledge of the responses to injury primarily come from animal studies and research using eccentric exercise. Therefore, the aim of this study was to develop a model of contusion injury in human participants and, additionally, investigate and compare physiological responses to four impact loads. Methods Thirty-two males were exposed to a single impact of either 4.2, 5.2, 6.2 or 7.2kg, dropped from 67 cm, on to the vastus lateralis of one leg. Maximum voluntary and electrically induced quadriceps force, and pressure pain threshold were measured, and blood sampling carried out, prior to and 30min, 24, 48 and 72h post-impact. Magnetic resonance imaging was carried out 24h post-impact to quantify oedema. Results Despite impact force with 7.2kg (1681.4 ± 235.6 N) not being different to 6.2kg (1690.7 ± 117.6 N), 7.2kg resulted in greater volume of oedema, voluntary force loss, pain and elevations in creatine kinase than the other loads. Although electrically induced force changed over time, post-hoc analysis failed to identify any changes. Interleukin-6 and prostaglandin-E2 did not change over time for any of the loads. Significant correlations were found between oedema volume, pressure pain threshold and maximum voluntary contraction force. Conclusions This is the first experimental study to investigate traumatic loading of skeletal muscle and the subsequent physiological responses associated with contusion injuries in humans. The absence of immediate elevations in creatine kinase and changes in electrically induced force suggest impact, with forces similar to those experienced in contact sport, does not cause significant, direct damage to skeletal muscle. However, the relationship between oedema volume, changes in pressure pain threshold and maximum voluntary contraction force suggests central inhibition plays a role in contusion-related muscle dysfunction.
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    Characterising the Cytokine and Circulating Immune Cell Response After a Single Bout of Eccentric Stepping Exercise in Healthy Untrained Males
    (Springer Nature, 2023-05-15) Lomiwes D; Barnes M; Shaw O; Ngametua N; Sawyer GM; Burr NS; Miller MR
    Purpose The mechanisms that underpin exercise-induced muscle damage and recovery are believed to be mediated, in part, by immune cells recruited to the site of injury. The aim of this study was to characterise the effects of muscle damage from bench-stepping on circulating cytokine and immune cell populations post-exercise and during recovery. Methods Ten untrained, healthy male volunteers completed 30 min of bench-stepping exercise to induce muscle damage to the eccentrically exercised leg. Muscle function, muscle pain and soreness were measured before, immediately after and 24, 48 and 72 h after exercise. Plasma creatine kinase, cartilage oligomeric matrix protein, cytokines and circulating immune cell phenotyping were also measured at these timepoints. Results Significant decreases occurred in eccentric, isometric and concentric (P = 0.018, 0.047 and 0.003, respectively) muscle function in eccentrically, but not concentrically, exercised quadriceps post-exercise. Plasma monocyte chemoattractant protein (MCP)-1 concentrations significantly increased immediately after exercise (69.0 ± 5.8 to 89.5 ± 10.0 pg/mL), then declined to below pre-exercise concentrations (58.8 ± 6.3 pg/mL) 72 h after exercise. These changes corresponded with the significant decrease of circulating CD45+ CD16− CD14+ monocytes (5.8% ± 1.5% to 1.9% ± 0.5%; Pre-exercise vs. 48 h) and increase of CD45+ CD3+ CD56− T-cells (60.5% ± 2.2% to 66.1% ± 2.1%; Pre-exercise vs. 72 h) during recovery. Conclusion Bench-stepping induced muscle damage to the quadriceps, which mediated systemic changes in MCP-1, monocytes and T-cells immediately post-exercise and during recovery. Further research is needed to clarify how modulations in immune subpopulations facilitate muscle recovery and adaptation following muscle damage.
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    Effects of Green and Gold Kiwifruit Varieties on Antioxidant Neuroprotective Potential in Pigs as a Model for Human Adults.
    (MDPI (Basel, Switzerland), 2024-04-09) Kanon AP; Giezenaar C; Roy NC; Jayawardana IA; Lomiwes D; Montoya CA; McNabb WC; Henare SJ; Digiacomo M
    Kiwifruit (KF) has shown neuroprotective potential in cell-based and rodent models by augmenting the capacity of endogenous antioxidant systems. This study aimed to determine whether KF consumption modulates the antioxidant capacity of plasma and brain tissue in growing pigs. Eighteen male pigs were divided equally into three groups: (1) bread, (2) bread + Actinidia deliciosa cv. 'Hayward' (green-fleshed), and (3) bread + A. chinensis cv. 'Hort16A' (yellow-fleshed). Following consumption of the diets for eight days, plasma and brain tissue (brain stem, corpus striatum, hippocampus, and prefrontal cortex) were collected and measured for biomarkers of antioxidant capacity, enzyme activity, and protein expression assessments. Green KF significantly increased ferric-reducing antioxidant potential (FRAP) in plasma and all brain regions compared with the bread-only diet. Gold KF increased plasma ascorbate concentration and trended towards reducing acetylcholinesterase activity in the brain compared with the bread-only diet. Pearson correlation analysis revealed a significant positive correlation between FRAP in the brain stem, prefrontal cortex, and hippocampus with the total polyphenol concentration of dietary interventions. These findings provide exploratory evidence for the benefits of KF constituents in augmenting the brain's antioxidant capacity that may support neurological homeostasis during oxidative stress.
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    The Efficacy of New Zealand Greenshell™ Mussel Powder Supplementation in Supporting Muscle Recovery Following Eccentric Exercise-Induced Muscle Damage in Healthy, Untrained Adult Males
    (MDPI (Basel, Switzerland), 2023-05-15) Lomiwes D; Barnes M; Shaw O; Ngametua N; Sawyer G; Burr N; Hedderley D; Kanon A; Bear T; Carroll A; Bentley_Hewitt K; Tian HS; Miller MR; Nieman DC
    Unaccustomed eccentric exercise results in muscle damage limiting physical performance for several days. This study investigated if Greenshell™ mussel (GSM) powder consumption expedited muscle recovery from eccentric exercise-induced muscle damage (EIMD). Methods: Twenty untrained adult men were recruited into a double-blind, placebo-controlled, cross-over study and were randomly assigned to receive the GSM powder or placebo treatment first. Participants consumed their allocated intervention for four weeks then completed a bench-stepping exercise that induced muscle damage to the eccentrically exercised leg. Muscle function, soreness and biomarkers of muscle damage, oxidative stress and inflammation were measured before exercise, immediately after exercise and 24, 48 and 72 h post exercise. GSM powder promoted muscle function recovery, significantly improving (p < 0.05) isometric and concentric peak torque at 48 h and 72 h post exercise, respectively. Participants on the GSM treatment had faster dissipation of soreness, with significant treatment × time interactions for affective (p = 0.007) and Visual Analogue Scale-assessed pain (p = 0.018). At 72 h, plasma creatine kinase concentrations in the GSM group were lower (p < 0.05) compared with the placebo group. This study provides evidence for GSM powder being effective in supporting muscle recovery from EIMD.