Journal Articles

Now showing 1 - 3 of 3

The Effect of Pre-Exercise Caffeine and Glucose Ingestion on Endurance Capacity in Hypoxia: A Double-Blind Crossover Trial.
(MDPI (Basel, Switzerland), 2024-10-25) Chiu C-H; Chen C-C; Ali A; Wu S-L; Wu C-L; Nieman DC; Schroder H
The impact of caffeine and glucose supplementation in a hypoxic environment on endurance exercise performance remains inconclusive. The current study examined the effect of pre-exercise carbohydrate and caffeine supplementation on endurance exercise performance in an acute hypoxic environment. Eight healthy active young males participated in this double-blind, within-subjects crossover study. Participants ingested the test drink 60 min before exercising at 50% Wmax for 90 min on a cycle ergometer (fatiguing preload); there followed an endurance performance test at 85% Wmax until exhaustion in a hypoxic chamber (~15%O2). Participants completed four experimental trials in a randomized order: caffeine (6 mg·kg-1; Caff), glucose (1 g·kg-1; CHO), caffeine (6 mg·kg-1) + glucose (1 g·kg-1; Caff-CHO), and taste- and color-matched placebo with no caffeine or CHO (PLA). Blood samples were collected during fasting, pre-exercise, every 30 min throughout the exercise, and immediately after exhaustion. The caffeine and glucose trials significantly enhanced endurance capacity in hypoxic conditions by Caff, 44% (68.8-31.5%, 95% confidence interval), CHO, 31% (44.7-15.6%), and Caff-CHO, 46% (79.1-13.2%). Plasma-free fatty-acid and glycerol concentrations were higher in Caff and PLA than in CHO and Caff-CHO (p < 0.05). The estimated rate of fat oxidation was higher in Caff and PLA than in CHO and Caff-CHO (p < 0.05). There were no significant differences in ratings of perceived exertion between trials. In conclusion, the ingestion of caffeine, glucose, or caffeine + glucose one hour before exercising in hypoxic conditions significantly improved 85% Wmax endurance performance after prolonged exercise.
Effect of curcumin supplementation on exercise-induced muscle damage: a narrative review
(Springer-Verlag GmbH Germany, part of Springer Nature, 2022-07-13) Nanavati K; Rutherfurd-Markwick K; Lee SJ; Bishop NC; Ali A
Curcumin, a natural polyphenol extracted from turmeric, is a potent antioxidant and anti-inflammatory agent. In the past few decades, curcumin's ability to impact chronic inflammatory conditions such as metabolic syndrome, arthritis, and cancer has been widely researched, along with growing interest in understanding its role in exercise-induced muscle damage (EIMD). EIMD impacts individuals differently depending on the type (resistance exercise, high-intensity interval training, and running), intensity, and duration of the exercise. Exercise disrupts the muscles' ultrastructure, raises inflammatory cytokine levels, and can cause swelling in the affected limb, a reduction in range of motion (ROM), and a reduction in muscular force-producing capacity. This review focuses on the metabolism, pharmacokinetics of various brands of curcumin supplements, and the effect of curcumin supplementation on EIMD regarding muscle soreness, activity of creatine kinase (CK), and production of inflammatory markers. Curcumin supplementation in the dose range of 90-5000 mg/day can decrease the subjective perception of muscle pain intensity, increase antioxidant capacity, and reduce CK activity, which reduces muscle damage when consumed close to exercise. Consumption of curcumin also improves muscle performance and has an anti-inflammatory effect, downregulating the production of pro-inflammatory cytokines, including TNF-α, IL-6, and IL-8. Curcumin may also improve oxidative capacity without hampering training adaptations in untrained and recreationally active individuals. The optimal curcumin dose to ameliorate EIMD is challenging to assess as its effect depends on the curcumin concentration in the supplement and its bioavailability.
Pharmacokinetics of Nitrate and Nitrite Following Beetroot Juice Drink Consumption
(MDPI (Basel, Switzerland), 2021-01-20) Jakubcik EM; Rutherfurd-Markwick K; Chabert M; Wong M; Ali A
BACKGROUND: Nitrate (NO3 -)-rich beetroot (BR) juice supplementation has been shown to improve cardiovascular function via reduction to nitrite (NO2 -) and then to the bioactive molecule nitric oxide (NO). However, limited research exists for the role of inorganic NO2 - that is contained naturally within BR. OBJECTIVE: As BR juice can naturally contain both NO3 - and NO2 - the objective of this study was to evaluate the individual effects of NO3 - and NO2 - consumed from BR on plasma [NO3 -]/[NO2 -] and their subsequent effects on various cardiovascular measures. DESIGN: In four separate treatments, 11 healthy adults consumed 250 mL of BR containing one of the following: (i) high NO3 -, low NO2 - (HL; 572 mg NO3 -, 32 mg NO2 -); (ii) medium NO3 -, medium NO2 - (MM; 280 mg NO3 -, 237 mg NO2 -); (iii) low NO3 -, medium NO2 - (LM; 43 mg NO3 -, 262 mg NO2 -); (iv) placebo (PL; low NO3 -, low NO2 -: 8 mg NO3 -, 5.8 mg NO2 -). Plasma [NO3 -]/[NO2 -], blood pressure, heart rate, mean arterial pressure (MAP), cardiac output and stroke volume were measured at baseline and every hour or second hour for 6 h post-BR consumption. OUTCOMES: Ingestion of the HL and MM BR increased plasma [NO2 -] and [NO3 -] after 2 h, with both remaining elevated after 6 h (p < 0.05). LM increased plasma [NO3 -] (p < 0.05) but did not increase plasma [NO2 -] compared to PL (p = 0.177). MAP was lower following the consumption of HL at 4 h and LM at 6 h (p < 0.05). CONCLUSION: Inorganic NO3 - consumption is the critical factor in elevating plasma [NO3 -] and [NO2 -]; however, both NO2 - and NO3 - show potential to reduce MAP. The known reduction of systolic blood pressure (SBP)/diastolic blood pressure (DBP) following NO3 - supplementation was not observed, making it unclear if NO2 - contributes to a reduction in SBP/DBP alongside NO3 -.

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