Browsing by Author "Sibson, Rachael"

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    Markers of oxidative stress, skeletal muscle mass and function, and their responses to resistance exercise training in older adults
    (Elsevier, 2018-01-09) Carru, Ciriaco; Da Boit, Mariasole; Paliogiannis, P.; Zinellu, Angelo; Sotgia, Salvatore; Sibson, Rachael; Meakin, Judith R.; Aspden, Richard M.; Mangoni, Arduino A.; Gray, Stuart R.
    BACKGROUND: Oxidative stress (OS) negatively affects skeletal muscle homeostasis in experimental models of ageing. However, little is known about the associations between circulating OS markers and parameters of muscle mass and function, and their responses to exercise training, in humans. METHODS: Maximal voluntary contraction (MVC, primary outcome) and isokinetic torque of the knee extensors at 30° s-1 (MIT), muscle cross-sectional area (MCSA) and quality (MQ, secondary outcomes), and plasma concentrations of malondialdehyde (MDA, pro-OS), homocysteine (HCY, pro-OS), taurine (TAU, anti-OS), and protein sulphydryl groups (PSH, anti-OS) were measured in 27 healthy older males and 23 females at baseline and after an 18-week resistance exercise program, with or without a nutritional intervention (fish oil vs. placebo). RESULTS: After adjusting for age, glomerular filtration rate, and nutritional intervention, there were no significant correlations between baseline OS markers and muscle parameters, barring a positive association between TAU and MIT in females (r = 0.53, P = .035) and between MDA and MCSA in males (r = 0.69, P = .001). Training did not significantly change OS markers, except for a reduction in MDA in females (-0.27 μmol/L, 95% CI -0.51 to -0.02, P = .034). In females, there were significant correlations between baseline MDA and exercise-induced changes in MVC (P = .018), baseline TAU and changes in MCSA (P = .026), and baseline HCY and changes in MCSA (P = .046) and MQ (P = .022). In males, baseline MDA was significantly associated with exercise-induced changes in MVC (P = .040). CONCLUSIONS: Plasma MDA, HCY, and TAU were significantly associated with baseline and/or exercise-induced changes in muscle mass and function in healthy older adults, primarily in females. Pending further confirmation in other populations, specific OS markers, particularly MDA, might predict muscle responses to resistance exercise programs in old age.
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    Sex differences in the associations between L-arginine pathway metabolites, skeletal muscle mass and function, and their responses to resistance exercise, in old age
    (Springer, 2017-09-02) Da Boit, Mariasole; Tommasi, Sara; Elliot, David; Zinellu, Angelo; Sotgia, Salvatore; Sibson, Rachael; Meakin, Judith R.; Aspden, Richard M.; Carru, Ciriaco; Mangoni, Arduino A.; Gray, Stuart R.
    Objectives The current study was designed to explore the associations between L-arginine metabolites and muscle mass and function in old age, which are largely unknown. Design The study used a randomised, double-blind, placebo-controlled design. Setting The study was carried out in a laboratory setting. Participants 50 healthy older adults [median age 70 years (IQR 67-73); 27 males]. Intervention Participants undertook an 18-week resistance exercise program, and a nutritional intervention (fish oil vs. placebo). Measurements Serum homoarginine, ornithine, citrulline, asymmetric dimethylarginine (ADMA), NG-monomethyl-L-arginine (L-NMMA), and symmetric dimethylarginine (SDMA), maximal voluntary contraction (MVC) and isokinetic torque of the knee extensors at 30° s-1 (MIT), muscle cross sectional area (MCSA) and quality (MQ) were measured at baseline and after the intervention. Results No significant exercise-induced changes were observed in metabolite concentrations. There were significant sex differences in the associations between metabolites and muscle parameters. After adjusting for age, glomerular filtration rate and fish oil intervention, citrulline (P=0.002) and ornithine (P=0.022) were negatively associated with MCSA at baseline in males but not females. However, baseline citrulline was negatively correlated with exercise-induced changes in MVC (P=0.043) and MQ (P=0.026) amongst females. Furthermore, amongst males, baseline homoarginine was positively associated with exercise-induced changes in MVC (P=0.026), ADMA was negatively associated with changes in MIT (P=0.026), L-NMMA (p=0.048) and ornithine (P<0.001) were both positively associated with changes in MCSA, and ornithine was negatively associated with changes in MQ (P=0.039). Conclusion Therefore, barring citrulline, there are significant sex differences in the associations between L-arginine metabolites and muscle mass and function in healthy older adults. These metabolites might enhance sarcopenia risk stratification, and the success of exercise programs, in old age.
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    Sex differences in the effect of fish-oil supplementation on the adaptive response to resistance exercise training in older people: A randomized controlled trial
    (American Society for Nutrition, 2016-11-16) Da Boit, Mariasole; Sibson, Rachael; Sivasubramaniam, Selvaraj; Meakin, Judith R.; Greig, Carolyn A.; Aspden, Richard M.; Thies, Frank; Jeromson, Stewart; Hamilton, D Lee; Speakman, John R.; Hambly, Catherine; Mangoni, Arduino A.; Preston, Thomas; Gray, Stuart R.
    Background: Resistance exercise increases muscle mass and function in older adults, but responses are attenuated compared with younger people. Data suggest that long-chain n–3 polyunsaturated fatty acids (PUFAs) may enhance adaptations to resistance exercise in older women. To our knowledge, this possibility has not been investigated in men. Objective: We sought to determine the effects of long-chain n–3 PUFA supplementation on resistance exercise training–induced increases in muscle mass and function and whether these effects differ between older men and women. Design: Fifty men and women [men: n = 27,mean 6 SD age: 70.6 6 4.5 y, mean 6 SD body mass index (BMI; in kg/m2), 25.6 6 4.2; women: n = 23, mean 6 SD age: 70.7 6 3.3 y, mean 6 SD BMI: 25.3 6 4.7] were randomly assigned to either long-chain n–3 PUFA (n = 23; 3 g fish oil/d) or placebo (n = 27; 3 g safflower oil/d) and participated in lower-limb resistance exercise training twice weekly for 18 wk. Muscle size, strength, and quality (strength per unit muscle area), functional abilities, and circulating metabolic and inflammatory markers were measured before and after the intervention. Results: Maximal isometric torque increased after exercise training to a greater (P , 0.05) extent in the long-chain n–3 PUFA group than in the placebo group in women, with no differences (P . 0.05) between groups in men. In both sexes, the effect of exercise training on maximal isokinetic torque at 30, 90, and 2408 s21, 4-m walk time, chair-rise time, muscle anatomic cross-sectional area, and muscle fat did not differ (P . 0.05) between groups. There was a greater (P , 0.05) increase in muscle quality in women after exercise training in the long-chain n–3 PUFA group than in the placebo group, with no such differences in men (P . 0.05). Long-chain n–3 PUFAs resulted in a greater decrease (P , 0.05) than the placebo in plasma triglyceride concentrations in both sexes, with no differences (P . 0.05) in glucose, insulin, or inflammatory markers. Conclusion: Long-chain n–3 PUFA supplementation augments increases in muscle function and quality in older women but not in older men after resistance exercise training.
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    Sex differences in the response to resistance exercise training in older people
    (The American Physiological Society and The Physiological Society, 2016-06-28) Da Boit, Mariasole; Sibson, Rachael; Meakin, Judith R.; Aspden, Richard M.; Thies, Frank; Mangoni, Arduino A.; Gray, Stuart R.
    Resistance exercise training is known to be effective in increasing muscle mass in older people. Acute measurement of protein metabolism data has indicated that the magnitude of response may differ between sexes. We compared adaptive responses in muscle mass and function to 18 weeks resistance exercise training in a cohort of older (>65 years) men and women. Resistance exercise training improved knee extensor maximal torque, 4 m walk time, time to complete five chair rises, muscle anatomical cross‐sectional area (ACSA) and muscle quality with no effect on muscle fat/water ratio or plasma glucose, insulin, triacylglycerol, IL‐6, and TNF‐α. Differences between sexes were observed for knee extensor maximal torque and muscle quality with greater increases observed in men versus women (P < 0.05). Maximal torque increased by 15.8 ± 10.6% in women and 41.7 ± 25.5% in men, whereas muscle quality increased by 8.8 ± 17.5% in women and by 33.7 ± 25.6% in men. In conclusion, this study has demonstrated a difference in the magnitude of adaptation, of some of the outcome measures employed, in response to 18 weeks of resistance exercise training between men and women. The mechanisms underlying this observation remain to be established.