Journal Articles
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Item 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 HThe 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.Item Carbohydrates and Endurance Exercise: A Narrative Review of a Food First Approach.(MDPI (Basel, Switzerland), 2023-03-11) Naderi A; Gobbi N; Ali A; Berjisian E; Hamidvand A; Forbes SC; Koozehchian MS; Karayigit R; Saunders B; Stanhope KLCarbohydrate (CHO) supplements such as bars, gels, drinks and powders have become ubiquitous as effective evidence-based CHO sources that improve endurance exercise performance. However, athletes are increasingly turning to more cost-effective 'food-first' approaches for CHO ingestion to improve exercise performance. Mixed CHO foods including cooked lentils, oats, honey, raisins, rice, and potatoes are all effective pre-exercise CHO food sources. Caution is advised when selecting some of these foods as a primary CHO source, as some athletes may be prone to gastrointestinal discomfort-especially regarding those foods where the quantities required for recommended CHO intake may be voluminous (e.g., potatoes). Palatability may be another barrier to the ingestion of some of these CHO-rich foods. Although most of these CHO-rich foods appear effective for exercise performance or recovery when consumed pre- and post-exercise, not all are viable to ingest during exercise due to difficulties in the quantities required, transport, and/or gastrointestinal discomfort. Raisins, bananas and honey may be particularly useful CHO foods for consumption during exercise, as they are easily transportable. Athletes should trial CHO food sources before, during and/or following training before implementation during competition.Item Secondary School Students and Caffeine: Consumption Habits, Motivations, and Experiences.(MDPI (Basel, Switzerland), 2023-02-17) Turner S; Ali A; Wham C; Rutherfurd-Markwick K; Cornelis M; Tauler PAdolescents may be particularly vulnerable to the effects of caffeine due to a lack of tolerance, their small size, changing brain physiology, and increasing independence. Concerns about adolescent caffeine consumption relate to potentially serious physiological and psychological effects following consumption. Motivations driving caffeine intake are not well understood among adolescents but are important to understand to reduce harmful behavioural patterns. This study explored caffeine consumption habits (sources, amount, frequency) of New Zealand adolescents; and factors motivating caffeine consumption and avoidance. The previously validated caffeine consumption habits questionnaire (CaffCo) was completed by 216 participants (15-18 years), with most (94.9%) consuming at least one caffeinated product daily. Chocolate, coffee, tea, and kola drinks were the most consumed sources. The median caffeine intake was 68 mg·day-1. Gender (boy) and being employed influenced the source, but not the quantity of caffeine consumed. One-fifth (21.2%) of adolescents consumed more than the recommended European Food Safety Authority (EFSA) safe level (3 mg·kg-1·day-1). Taste, energy, and temperature were the main motivators for consumption, and increased energy, excitement, restlessness, and sleep disturbances were reported effects following caffeine consumption. This study provides information on caffeinated product consumption among New Zealand adolescents, some of whom consumed caffeine above the EFSA safe level. Public health initiatives directed at adolescents may be important to reduce potential caffeine-related harm.Item Nutrient Dense, Low-Cost Foods Can Improve the Affordability and Quality of the New Zealand Diet-A Substitution Modeling Study(MDPI (Basel, Switzerland), 2021-07-27) Starck CS; Blumfield M; Keighley T; Marshall S; Petocz P; Inan-Eroglu E; Abbott K; Cassettari T; Ali A; Wham C; Kruger R; Kira G; Fayet-Moore FThe high prevalence of non-communicable disease in New Zealand (NZ) is driven in part by unhealthy diet selections, with food costs contributing to an increased risk for vulnerable population groups. This study aimed to: (i) identify the nutrient density-to-cost ratio of NZ foods; (ii) model the impact of substituting foods with a lower nutrient density-to-cost ratio with those with a higher nutrient density-to-cost ratio on diet quality and affordability in representative NZ population samples for low and medium socioeconomic status (SES) households by ethnicity; and (iii) evaluate food processing level. Foods were categorized, coded for processing level and discretionary status, analyzed for nutrient density and cost, and ranked by nutrient density-to-cost ratio. The top quartile of nutrient dense, low-cost foods were 56% unprocessed (vegetables, fruit, porridge, pasta, rice, nuts/seeds), 31% ultra-processed (vegetable dishes, fortified bread, breakfast cereals unfortified <15 g sugars/100 g and fortified 15–30 g sugars/100 g), 6% processed (fruit juice), and 6% culinary processed (oils). Using substitution modeling, diet quality improved by 59% and 71% for adults and children, respectively, and affordability increased by 20–24%, depending on ethnicity and SES. The NZ diet can be made healthier and more affordable when nutritious, low-cost foods are selected. Processing levels in the healthier, modeled diet suggest that some non-discretionary ultra-processed foods may provide a valuable source of low-cost nutrition for food insecure populations.Item Effects of carbohydrate and caffeine mouth rinsing on strength, muscular endurance and cognitive performance(Taylor and Francis Group on behalf of the International Society of Sports Nutrition, 2021-09-24) Karayigit R; Ali A; Rezaei S; Ersoz G; Lago-Rodriguez A; Domínguez R; Naderi ABACKGROUND: Carbohydrate (CHO) and caffeine (CAF) mouth rinsing have been shown to enhance endurance and sprint performance. However, the effects of CHO and CAF mouth rinsing on muscular and cognitive performance in comparison between male and female athletes are less well-established. The aim of this study was to examine the effect of CHO and CAF rinsing on squat and bench press 1 repetition maximum (1-RM) strength, 3 sets of 40% of 1-RM muscular endurance and cognitive performance in both male and female athletes. METHODS: Thirteen male and fourteen female resistance-trained participants completed four testing sessions following the rinsing of 25 ml of i) 6% of CHO (1.5 g); ii) 2% CAF (500 mg), iii) combined CHO and CAF (CHOCAF) solutions or iv) water (PLA) for 10 s. Heart rate (HR), felt arousal (FA), ratings of perceived exertion (RPE) and glucose (GLU) were recorded throughout the test protocol. RESULTS: There were no significant differences in squat and bench press 1-RM, HR, RPE and GLU (p > 0.05) for males and females, respectively. FA was significantly increased with CAF (p = 0.04, p = 0.01) and CHOCAF (p = 0.03, p = 0.01) condition in both males and females, respectively. Squat endurance performance in the first set was significantly increased with CHOCAF condition compared to PLA in both males (p = 0.01) and females (p = 0.02). Bench press endurance was similar for all conditions in both genders (p > 0.05). Cognitive performance was significantly increased with CHOCAF compared to PLA in males (p = 0.03) and females (p = 0.02). CONCLUSION: Combined CHO and CAF mouth rinsing significantly improved lower body muscular endurance and cognitive performance in both males and females.Item 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 ACurcumin, 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.Item The Effect of a 14-Day gymnema sylvestre Intervention to Reduce Sugar Cravings in Adults(MDPI (Basel, Switzerland), 2022-12-12) Turner S; Diako C; Kruger R; Wong M; Wood W; Rutherfurd-Markwick K; Stice E; Ali AGymnemic-acids (GA) block lingual sweet taste receptors, thereby reducing pleasantness and intake of sweet food. Objective: To examine whether a 14-day gymnema-based intervention can reduce sweet foods and discretionary sugar intake in free-living adults. Healthy adults (n = 58) were randomly allocated to either the intervention group (INT) or control group (CON). The intervention comprised of consuming 4 mg of Gymnema sylvestre containing 75% gymnema acids, a fibre and vitamin supplement, and an associated healthy-eating guide for 14 days; participants in the CON group followed the same protocol, replacing the GA with a placebo mint. Amount of chocolate bars eaten and sensory testing were conducted before and after the 14-day intervention (post-GA or placebo dosing on days zero and 15, respectively). Food frequency questionnaires were conducted on days zero, 15 and after a 28-day maintenance period to examine any changes in intake of sweet foods. A range of statistical procedures were used to analyse the data including Chi square, t-test and two-way analysis of variance. Post dosing, INT consumed fewer chocolates (2.65 ± 0.21 bars) at day zero than CON (3.15 ± 0.24 bars; p = 0.02); there were no differences between groups at day 15 (INT = 2.77 ± 0.22 bars; CON = 2.78 ± 0.22 bars; p = 0.81). At both visits, a small substantive effect (r < 0.3) was observed in the change in pleasantness and desire ratings, with INT showing a slight increase while CON showed a small decrease over the 14-day period. No differences were found in the intake of 9 food categories between groups at any timepoint. There were no differences in consumption of low sugar healthy foods between visits, or by group. The 14-day behavioural intervention reduced pleasantness and intake of chocolate in a laboratory setting. There was no habituation to the mint over the 14-day period. This study is the first to investigate the effect of longer-term gymnema acid consumption on sweet food consumption outside of a laboratory setting; further research is needed to assess how long the effect of the 14-day intervention persists.Item 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 ABACKGROUND: 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 -.Item Motivations for Caffeine Consumption in New Zealand Tertiary Students(MDPI (Basel, Switzerland), 2021-11-25) Stachyshyn S; Wham C; Ali A; Knightbridge-Eager T; Rutherfurd-Markwick KCaffeine-related health incidents in New Zealand have escalated over the last two decades. In order to reduce the risk of substance-related harm, it is important to understand the consumers' motivations for its use. This is especially true for tertiary students who are presumed to be at a higher risk due to seeking out caffeine's well-known cognitive benefits as well as the targeted marketing of such products to young adults. This study examined the habits and motivations for caffeine consumption in tertiary students in New Zealand. A previously validated caffeine consumption-habits (CaffCo) questionnaire was administered online to 317 tertiary students (n = 169 females), aged ≥16 years. Of the 99.1% of participants who regularly consumed caffeine, coffee (76.3%) tea (71.6%) and chocolate (81.7%) consumption were the most prevalent. Motivations for caffeinated-product consumption differed according to caffeine source. Tea was consumed for the warmth and taste, coffee was consumed to stay awake and for warmth, and chocolate, for the taste and as a treat. Marketing was not identified by participants as influencing their consumption of caffeinated products. Knowledge of motivations for caffeine consumption may assist in identifying strategies to reduce caffeine intake in those New Zealand tertiary students who regularly consume amounts of caffeine that exceed safe level.Item Caffeine Consumption Habits of New Zealand Tertiary Students(MDPI (Basel, Switzerland), 2021-04-28) Stachyshyn S; Ali A; Wham C; Knightbridge-Eager T; Rutherfurd-Markwick KAdverse effects associated with excessive caffeine consumption combined with increasing numbers and availability of caffeine-containing products are causes for concern. Tertiary students may be at increased risk of consuming excessive amounts of caffeine due to seeking caffeinated products with well-known wakefulness effects and cognitive benefits. This study explored caffeine consumption habits of New Zealand tertiary students (317; ≥16-years) using a previously validated caffeine consumption habits (CaffCo) questionnaire. Most (99.1%) regularly consumed caffeinated products, especially chocolate, coffee and tea, with coffee, tea and energy drinks contributing most to total caffeine intake. Median estimated caffeine intake was 146.73 mg·day-1, or 2.25 mg·kgbw-1·day-1. Maximum and minimum intakes were 1988.14 mg·day-1 (23.51 mg·kgbw-1·day-1) and 0.07 mg·day-1 (0.02 mg·kgbw-1·day-1), respectively. One-third (34.4%) of caffeine consumers ingested caffeine above the adverse effect level (3 mg·kgbw-1·day-1) and 14.3% above the safe limit (400 mg·day-1). Most caffeine consumers (84.7%), reported experiencing at least one 'adverse symptom' post-caffeine consumption, of which 25.7% reported effects leading to distress or negatively impacting their life. Experiencing 'adverse symptoms' did not, however, curtail consumption in the majority of symptomatic participants (~77%). Public health initiatives directed at tertiary students may be important to reduce potential caffeine-related harm.