Helen O'Connor

University of Sydney, Sydney, New South Wales, Australia

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Publications (57)121.75 Total impact

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    ABSTRACT: Competitive bodybuilders are well known for extreme physique traits and extremes in diet and training manipulation to optimize lean mass and achieve a low body fat. Although many of the dietary dogmas in bodybuilding lack scientific scrutiny, a number, including timing and dosing of high biological value proteins across the day, have more recently been confirmed as effective by empirical research studies. A more comprehensive understanding of the dietary intakes of bodybuilders has the potential to uncover other dietary approaches, deserving of scientific investigation, with application to the wider sporting, and potential health contexts, where manipulation of physique traits is desired. Our objective was to conduct a systematic review of dietary intake practices of competitive bodybuilders, evaluate the quality and currency of the existing literature, and identify research gaps to inform future studies. A systematic search of electronic databases was conducted from the earliest record until March 2014. The search combined permutations of the terms 'bodybuilding', 'dietary intake', and 'dietary supplement'. Included studies needed to report quantitative data (energy and macronutrients at a minimum) on habitual dietary intake of competitive bodybuilders. The 18 manuscripts meeting eligibility criteria reported on 385 participants (n = 62 women). Most studies were published in the 1980-1990s, with three published in the past 5 years. Study methodological quality was evaluated as poor. Energy intake ranged from 10 to 24 MJ/day for men and from 4 to 14 MJ/day for women. Protein intake ranged from 1.9 to 4.3 g/kg for men and from 0.8 to 2.8 g/kg for women. Intake of carbohydrate and fat was <6 g/kg/day and below 30 % of energy, respectively. Carbohydrate intakes were below, and protein (in men) intakes were higher than, the current recommendations for strength athletes, with no consideration for exploration of macronutrient quality or distribution over the day. Energy intakes varied over different phases of preparation, typically being highest in the non-competition (>6 months from competition) or immediate post-competition period and lowest during competition preparation (≤6 months from competition) or competition week. The most commonly reported dietary supplements were protein powders/liquids and amino acids. The studies failed to provide details on rationale for different dietary intakes. The contribution of diet supplements was also often not reported. When supplements were reported, intakes of some micronutrients were excessive (~1000 % of US Recommended Dietary Allowance) and above the tolerable upper limit. This review demonstrates that literature describing the dietary intake practices of competitive bodybuilders is dated and often of poor quality. Intake reporting required better specificity and details of the rationale underpinning the use. The review suggests that high-quality contemporary research is needed in this area, with the potential to uncover dietary strategies worthy of scientific exploration.
    04/2015; DOI:10.1007/s40279-015-0329-4
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    ABSTRACT: Background/Aims: Non-alcoholic fatty liver disease (NAFLD) is an independent predictor of CVD. Omega-3 PUFA supplementation has been shown to improve NAFLD. This study aimed to examine the relationship of the Omega-3 Index (O3I; a biomarker of omega-3 status) with liver fat (intrahepatic lipid concentration; IHL%). Methods: Eighty overweight/obese, healthy, non-smoker adults (56 males) undertook MRI and proton magnetic resonance spectroscopy (1H-MRS) to measure abdominal adiposity and IHL% within seven days of undergoing anthropometric measurements and providing a blood sample for biochemical and erythrocyte lipid analysis. Correlations with liver fat were examined and linear regression for the prediction of IHL% was performed. Mean±SEM are reported. Results: O3I was high in participants with (9.0±0.3) and without (8.4±0.3) NAFLD, and was positively correlated with IHL% (r=0.255, P=0.029), although further analysis revealed this was stronger and statistically significant for males (r=0.425, P=0.001) and not females (r=0.020, P=0.925). Linear regression showed that O3I and erythrocyte n-6/n-3 ratio together significantly explained 28% of the variance in IHL% (P=0.046). The addition of BMI, waist and age raised the predictive power to 58% (P<0.001). Further addition of biochemical markers (TAG, HDL, high-sensitive CRP (hsCRP)) increased the total variance explained by the model to 66%. Conclusions: In overweight/obese adults, O3I was unexpectedly positively associated with IHL%, however gender differences apparent in this cohort warrant further research. In overweight obese adults, simple anthropometric and demographic measures may be of equal or greater utility than erythrocyte PUFA analysis in identifying those at increased risk of NAFLD. Funding source(s): Blackmores; Diabetes Australia.
    Nutrition Society of Australia 38th Annual Scientific Meeting, Hobart, Australia; 11/2014
  • Inge Spronk, Susan E Heaney, Tania Prvan, Helen T O'Connor
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    ABSTRACT: This study investigated the association between general nutrition knowledge and dietary quality in a convenience sample of athletes (≥ state level) recruited from four Australian State Sport Institutes. General nutrition knowledge was measured by the validated General Nutrition Knowledge Questionnaire and diet quality by an adapted version of the Australian Recommended Food Score (A-ARFS) calculated from food frequency questionnaire data. Analysis of variance and linear modelling were used to assess relationships between variables. Data: mean (Standard Deviation). A total of 101 athletes (Males: 37; Females: 64), 18.6 (4.6) years were recruited mainly from team sports (72.0%). Females scored higher than males for both nutrition knowledge (Females: 59.9%; Males: 55.6%; p=0.017) and total A-ARFS (Females: 54.2% Males: 49.4%; p=0.016). There was no significant influence of age, level of education, athletic calibre or team/individual sport participation on nutrition knowledge or total A-ARFS. However, athletes engaged in previous dietetic consultation had significantly higher nutrition knowledge (61.6% vs. 56.6%; p=0.034) but not total A-ARFS (53.6% vs. 52.0%; p=0.466). Nutrition knowledge was weakly but positively associated with total A-ARFS (r=0.261, p=0.008) and A-ARFS vegetable sub-group (r=0.252, p=0.024) independently explaining 6.8% and 5.1% of the variance respectively. Gender independently explained 5.6% of the variance in nutrition knowledge (p=0.017) and 6.7% in total A-ARFS (p=0.016). Higher nutrition knowledge and female gender were weakly but positively associated with better diet quality. Given the importance of nutrition to health and optimal sports performance, intervention to improve nutrition knowledge and healthy eating is recommended, especially for young male athletes.
    International journal of sport nutrition and exercise metabolism 09/2014; DOI:10.1123/ijsnem.2014-0034 · 1.98 Impact Factor
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    ABSTRACT: In athletes, caffeine use is common although its effects on sleep have not been widely studied. This randomised, double-blind, placebo-controlled crossover trial investigated the effects of late-afternoon caffeine and carbohydrate-electrolyte (CEB) co-ingestion on cycling performance and nocturnal sleep. Six male cyclists/triathletes (age 27.5 +/- A 6.9 years) completed an afternoon training session (TS; cycling 80 min; 65 % VO2max) followed by a 5 kJ kg(-1) cycling time trial (TT). Caffeine (split dose 2 x 3 mg kg(-1)) or placebo was administered 1 h prior and 40 min into the TS. A 7.4 % CEB (3 ml kg(-1) every 15 min) was administered during the TS, followed 30 min after by a standardised evening meal. Participants retired at their usual bedtime and indices of sleep duration and quality were monitored via polysomnography. Data: mean +/- A SD. All participants performed better in the caffeine TT (caffeine 19.7 +/- A 3.3; placebo 20.5 +/- A 3.5 min; p = 0.006), while ratings of perceived exertion (caffeine 12.0 +/- A 0.6; placebo 12.9 +/- A 0.7; p = 0.004) and heart rate (caffeine 175 +/- A 6; placebo 167 +/- A 11 bpm; p = 0.085) were lower in the caffeine TS. Caffeine intake induced significant disruptions to a number of sleep indices including increased sleep onset latency (caffeine 51.1 +/- A 34.7; placebo 10.2 +/- A 4.2 min; p = 0.028) and decreased sleep efficiency (caffeine 76.1 +/- A 19.6; placebo 91.5 +/- A 4.2 %; p = 0.028), rapid eye movement sleep (caffeine 62.1 +/- A 19.6; placebo 85.8 +/- A 24.7 min; p = 0.028) and total sleep time (caffeine 391 +/- A 97; placebo 464 +/- A 49 min; p = 0.028). This study supports a performance-enhancing effect of caffeine, although athletes (especially those using caffeine for late-afternoon/evening training and competition) should consider its deleterious effects on sleep.
    Arbeitsphysiologie 08/2014; 114(12). DOI:10.1007/s00421-014-2973-z · 2.30 Impact Factor
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    ABSTRACT: Glycemic index (GI) manipulation of pre-event meals has been used as a dietary strategy to enhance endurance exercise performance. The existing literature investigating this strategy appears equivocal however, a meta-analysis has not been conducted. PURPOSE: This systematic review evaluated the effect of a low GI (LGI) or high GI (HGI) pre-exercise meal on exercise performance using meta-analysis. METHODS: A systematic search was conducted to identify relevant randomized, crossover trials. Manuscripts were included if they used: non-sedentary, healthy participants aged ≥16 y; a LGI (<55) and HGI (>70) meal consumed 30-180 min prior to exercise; exercise protocols that included a time trial (TT) or time to exhaustion test (TTE) only, or a submaximal bout followed by a TT or TTE. Additional sub-analysis was conducted for studies where carbohydrate (CHO) was also consumed during exercise. After data extraction of participant, meal and exercise data, effect sizes (ES) and 95% confidence intervals (95% CI) were calculated for each study and an overall effect for each exercise protocol was determined. Data: ES (95% CI). RESULTS: The initial search yielded 3,431 citations. After exclusion of ineligible studies, 21 articles were included. Studies used a mix of active male and female participants (VO2peak - females: >44; males: >50 ml.kg-1.min-1). The CHO content of pre-exercise meals ranged from 0.17 g to 2 g.kg-1 of body mass. No significant effect of pre-exercise meal GI on TT performance was observed [ES: 0.17 (-0.16 to 0.51); p=0.31]. In submaximal + TT studies where no CHO was ingested during exercise, performance improved non-significantly with a HGI meal [ES: -0.28 (-1.01 to 0.44); p=0.45]. In studies where CHO was consumed during exercise, a LGI meal non-significantly enhanced performance [ES: 0.30 (-0.25 to 0.85); p=0.28]. TTE performance was not significantly improved by either meal type, although LGI was favored [ES: 0.40 (-0.31 to 1.11); p=0.27]. No consistent metabolic responses (glucose, insulin, lactate and respiratory exchange ratio) during exercise were observed with either a LGI or HGI meal. CONCLUSION: There was no clear ergogenic benefit of consuming either a LGI or HGI pre-exercise meal for endurance exercise performance.
    61st Annual Meeting of the American College of Sports Medicine, Orlando, USA; 05/2014
  • 61st Annual Meeting of the American College of Sports Medicine, Orlando, USA; 05/2014
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    ABSTRACT: Although iron deficiency is common in women especially during dieting, weight management trials rarely examine the longitudinal impact of genetics on iron. This study examined the associations between the TMPRSS6 rs855791 polymorphism and iron indices at baseline and after a 12-month trial comparing two weight loss diets (higher-protein, higher-haem iron (HPHI) vs lower-protein, lower-haem iron (LPLI)). A total of 76 young overweight women (18-25y; BMI⩾27.5 kg/m(2)) were included at baseline, with 27 (HPHI: n=15; LPLI: n=12) completing the 12-month trial. At baseline, C allele homozygotes exhibited higher serum iron (P=0.047) and lower hepcidin (P=0.023) compared with T allele carriers. After 12 months, no genotypic differences were observed for ferritin and soluble transferrin receptor, although C homozygotes on HPHI showed higher serum iron and transferrin saturation (P<0.05). Results indicate that rs855791 can influence iron metabolism to some extent, but its impact on storage and functional iron status is small relative to dietary protein/iron manipulation.European Journal of Clinical Nutrition advance online publication, 7 May 2014;; doi:10.1038/ejcn.2014.82.
    European journal of clinical nutrition 05/2014; DOI:10.1038/ejcn.2014.82 · 2.95 Impact Factor
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    ABSTRACT: The present systematic review examined the relationship between nutrition knowledge and dietary intake in adults (mean age ≥ 18 years). Relevant databases were searched from the earliest record until November 2012. Search terms included: nutrition; diet or food knowledge and energy intake; feeding behaviour; diet; eating; nutrient or food intake or consumption. Included studies were original research articles that used instruments providing quantitative assessment of both nutrition knowledge and dietary intake and their statistical association. The initial search netted 1 193 393 potentially relevant articles, of which twenty-nine were eligible for inclusion. Most of them were conducted in community populations (n 22) with fewer (n 7) in athletic populations. Due to the heterogeneity of methods used to assess nutrition knowledge and dietary intake, a meta-analysis was not possible. The majority of the studies (65·5 %: community 63·6 %; athletic 71·4 %) reported significant, positive, but weak (r< 0·5) associations between higher nutrition knowledge and dietary intake, most often a higher intake of fruit and vegetables. However, study quality ranged widely and participant representation from lower socio-economic status was limited, with most participants being tertiary educated and female. Well-designed studies using validated methodologies are needed to clarify the relationship between nutrition knowledge and dietary intake. Diet quality scores or indices that aim to evaluate compliance to dietary guidelines may be particularly valuable for assessing the relationship between nutrition knowledge and dietary intake. Nutrition knowledge is an integral component of health literacy and as low health literacy is associated with poor health outcomes, contemporary, high-quality research is needed to inform community nutrition education and public health policy.
    The British journal of nutrition 03/2014; 111(10):1-14. DOI:10.1017/S0007114514000087 · 3.34 Impact Factor
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    ABSTRACT: The control of eating behaviours such as hunger and disinhibition is problematic for women during weight management. Higher-protein (HP) diets have been shown to promote greater weight reduction than higher-carbohydrate (HC) diets, but their impact on eating behaviours is relatively unexplored. This study compared two iso-energetically restricted (5,600 kJ/day) diets differing in protein (HP: 32 %, HC: 20 %) and carbohydrate (HP: 41 %, HC: 58 %) on appetite ratings, restraint, disinhibition, perceived hunger and binge eating in 36 (HP: n = 21, HC: n = 15) young (18-25 years), healthy women with BMI ≥27.5 kg/m(2) who completed a 12-month clinical weight management trial. Dietary compliance and self-worth were also assessed. Results showed that both diets induced improvements in restraint and disinhibition from baseline (p < 0.01), with HP participants losing a non-significantly greater amount of weight than HC participants (HP: 9.6 ± 2.6, HC: 4.1 ± 1.4 kg, p = 0.07). Despite reasonable compliance, no significant appetite and eating behaviour differences were observed between the diets. Reduction in disinhibition (regardless of diet) significantly predicted weight loss (β = 0.574, p < 0.001) and self-worth improvement (β = -0.463, p = 0.002), while HP intake predicted greater self-worth change (β = -0.371, p = 0.011). This study demonstrates that young women can improve restraint and disinhibition on a weight management programme, with the reduction in disinhibition shown to be a key predictor of weight loss. HP intake may offer some advantage for increasing self-worth but not eating behaviours. As HP diets are popular, these findings warrant confirmation in a larger sample.
    Eating and weight disorders: EWD 03/2014; 19(2). DOI:10.1007/s40519-014-0110-y · 0.68 Impact Factor
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    ABSTRACT: Objective. The purpose of this study was to assess the effect of high intensity interval training (HIIT) versus continuous aerobic exercise training (CONT) or placebo (PLA) on body composition by randomized controlled design. Methods. Work capacity and body composition (dual-energy X-ray absorptiometry) were measured before and after 12 weeks of intervention in 38 previously inactive overweight adults. Results. There was a significant group × time interaction for change in work capacity (P < 0.001), which increased significantly in CONT (23.8 ± 3.0%) and HIIT (22.3 ± 3.5%) but not PLA (3.1 ± 5.0%). There was a near-significant main effect for percentage trunk fat, with trunk fat reducing in CONT by 3.1 ± 1.6% and in PLA by 1.1 ± 0.4%, but not in HIIT (increase of 0.7 ± 1.0%) (P = 0.07). There was a significant reduction in android fat percentage in CONT (2.7 ± 1.3%) and PLA (1.4 ± 0.8%) but not HIIT (increase of 0.8 ± 0.7%) (P = 0.04). Conclusion. These data suggest that HIIT may be advocated as a time-efficient strategy for eliciting comparable fitness benefits to traditional continuous exercise in inactive, overweight adults. However, in this population HIIT does not confer the same benefit to body fat levels as continuous exercise training.
    Journal of obesity 01/2014; 2014:834865. DOI:10.1155/2014/834865
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    ABSTRACT: Objective. The purpose of this study was to assess the effect of high intensity interval training (HIIT) versus continuous aerobic exercise training (CONT) or placebo (PLA) on body composition by randomized controlled design. Methods. Work capacity and body composition (dual-energy X-ray absorptiometry) were measured before and after 12 weeks of intervention in 38 previously inactive overweight adults. Results. There was a significant group × time interaction for change in work capacity (), which increased significantly in CONT (%) and HIIT (%) but not PLA (%). There was a near-significant main effect for percentage trunk fat, with trunk fat reducing in CONT by % and in PLA by %, but not in HIIT (increase of %) (). There was a significant reduction in android fat percentage in CONT (%) and PLA (%) but not HIIT (increase of %) (). Conclusion. These data suggest that HIIT may be advocated as a time-efficient strategy for eliciting comparable fitness benefits to traditional continuous exercise in inactive, overweight adults. However, in this population HIIT does not confer the same benefit to body fat levels as continuous exercise training.
    Journal of obesity 01/2014; 2014.
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    ABSTRACT: Young overweight women are at risk of iron and zinc deficiency. This study assessed iron, zinc and inflammatory status during a 12-month weight loss trial in young women (18-25 y; BMI >=27.5 kg/m2) randomised to a higher-protein (HP: 32% protein; 12.2 mg/day iron; 11.7 mg/day zinc) or lower-protein (LP: 20%; 9.9 mg/day; 7.6 mg/day respectively) diet with contrasting haem iron and zinc content. In completers (HP: n=21; LP: n=15), HP participants showed higher median ferritin (52.0 vs 39.0 μg/L; p=0.021) and lower median soluble transferrin receptor-ferritin index (sTfR-F; 0.89 vs 1.05; p=0.024) although concentrations remained within normal range for both diets. Median C-reactive protein (CRP; HP: 3.54; LP: 4.63 mg/L) and hepcidin (HP: 5.70; LP: 8.25 ng/mL) were not elevated at baseline, and no longitudinal between-diet differences were observed for zinc and CRP. Compared to those with <5% weight loss, HP participants losing >=10% weight showed lower median sTfR-F (0.76 vs 1.03; p=0.019) at six months. Impact of >=10% weight loss on iron was more apparent in LP participants who exhibited greater mean serum iron (20.0 vs 13.5 μmol/L; p=0.002), transferrin saturation (29.8% vs 19.4%; p=0.001) and lower sTfR (1.24 vs 1.92 mg/L; p=0.034) at 12 months. Results show normal iron and zinc status can be maintained during 12 months of energy restriction. In the absence of elevated baseline inflammation and hepcidin, a more favourable iron profile in those with >=10% weight loss may reflect stronger compliance or the potential influence of iron regulatory mechanisms unrelated to inflammatory hepcidin reduction.
    Asia Pacific Journal of Clinical Nutrition 12/2013; 22(4):574-582. · 1.36 Impact Factor
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    ABSTRACT: Purpose: The purpose of this study was to establish whether sensory factors associated with cold-beverage ingestion exert an ergogenic effect on endurance performance independent of thermoregulatory or cardiovascular factors. Methods: Ten males performed three trials involving 90 min of steady state cycling (SS; 62% VO2max) in the heat (32.1 ± 0.9 °C, 40 ± 2.4% relative humidity) followed by a 4 kJ/kg body mass time trial (TT). During SS, participants consumed an identical volume (260 ± 38g) of sports beverage (7.4% carbohydrate) every 15 min as either ice slushy (-1 °C; ICE), thermoneutral liquid (37 °C; CON), or thermoneutral liquid consumption with expectorated ice slushy mouthwash (WASH). Results: Rectal temperature, hydration status, heart rate, and skin blood flow were not different between trials. Gastrointestinal (pill) temperature was lower in ICE (35.6 ± 2.7 °C) versus CON (37.4 ± 0.7 °C, p = .05). Heat storage tended to be lower with ICE during SS (14.7 ± 8.4W.m-2, p = .08) and higher during TT (68.9 ± 38.6W.m-2, p = .03) compared with CON (22.1 ± 6.6 and 31.4 ± 27.6W.m-2). ICE tended to lower the rating of perceived exertion (RPE, 12.9 ± 0.6, p = .05) and improve thermal comfort (TC, 4.5 ± 0.2; p = .01) vs. CON (13.8 ± 1.0 and 5.2 ± 0.2 respectively). WASH RPE (13.0 ± 0.8) and TC (4.8 ± 0.2) tended to be lower versus CON (p = .07 and p = .09 respectively). ICE improved performance (18:28 ± 1:03) compared with CON (20:24 ± 1:46) but not WASH (19:45 ± 1:43). Conclusion: Improved performance with ICE ingestion likely resulted from the creation of a gastrointestinal heat sink, reducing SS heat storage. Although the benefits of cold-beverage consumption are more potent when there is ingestion, improved RPE, TC, and meaningful performance improvement with WASH supports an independent sensory effect of presenting a cold stimulus to the mouth.
    International Journal of Sport Nutrition and Exercise Metabolism 10/2013; 23(5):458-69. · 1.98 Impact Factor
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    ABSTRACT: To comprehensively describe anthropometric characteristics of Australian junior elite rugby league players and assess potential anthropometric dissimilarities between players of varying positional groups, ethnicity (Polynesian vs. non-Polynesian) and playing level (junior vs. professional; using published data from Australian professional players). Cross-sectional study. Height, body mass, eight skinfolds, five girths and two bone breadths were measured with body fat (BF%) and somatotype calculated using population-appropriate equations. Data: mean±SD. This study recruited 116 junior players. Mean age, mass and BF% were 17±1y, 87.0±11.6kg and 14.0±4.6% respectively. Compared to backs, forwards had greater mass (92.6±12.2 vs. 80.9±7.1kg), skinfolds, girths, femur breadth, BF% (16.1±4.8% vs. 11.8±3.2%) (all p<0.01), and were more endo- and mesomorphic, but less ectomorphic (all p<0.001). Compared to other positional groups, props had greater mass, adiposity, calf girth and endomorphy, while adjustables (fullbacks, five-eighths, halfbacks, hookers) had the shortest stature (all p<0.01). Polynesians exhibited greater height (181.0±5.7 vs. 178.7±6.3cm), mass (90.6±11.7 vs. 84.7±11.1kg), arm and calf girths, bone breadths and mesomorphy (7.6±1.2 vs. 6.7±1.1) than non-Polynesians (all p<0.05). Juniors had lower height, mass, waist and smaller sum of skinfolds than professional players (all p<0.05). Greater mass, mesomorphy, adiposity and bone size in forwards is desirable for tackling and attacking and may protect against high impact forces sustained in this position. Advantageous anthropometric attributes exhibited in Polynesian players may influence selection into junior elite rugby league teams. Anthropometric data from this study may assist other junior players and coaches with training, dietary modification and position allocation.
    08/2013; DOI:10.1016/j.jsams.2013.07.020
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    ABSTRACT: Purpose: The aim of this study was to measure the effect of environmental conditions and aid-station beverage-cooling practices on the temperature of competitor beverages. Methods: Environmental and beverage temperatures were measured at three cycling and two run course aid stations at the 2010 Langkawi, Malaysia (MA), and Port Macquarie, Australia (AU), Ironman triathlon events. To measure the specific effect of radiant temperature, additional fluid-filled (600 ml) drink bottles (n = 12) were cooled overnight (C) and then placed in direct sun (n = 6) or shade (n = 6) near to a cycle aid station at AU. Results: During both events, beverage temperature increased over time (p < .05) as environmental conditions, particularly radiant temperature increased (p < .05). Mean beverage temperature ranged between 14-26°C and during both events was above the palatable range (15-22°C) for extended periods. At AU, bottles placed in direct sunlight heated faster (6.9 ± 2.3 °C·h-1) than those in the shade (4.8 ± 1.1°C·h-1, p = .05). Conclusion: Simple changes to Ironman aid-station practices, including shade and chilling beverages with ice, result in the provision of cooler beverages. Future studies should investigate whether provision of cool beverages at prolonged endurance events influences heat-illness incidence, beverage-consumption patterns, and competitor performance.
    International Journal of Sport Nutrition and Exercise Metabolism 08/2013; 23(4):418-24. · 1.98 Impact Factor
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    ABSTRACT: Evidence suggests obesity-related inflammation alters iron metabolism potentially increasing the risk of iron deficiency. This cross-sectional study aimed to investigate iron, hepcidin and inflammatory status in young, healthy overweight and obese women. 114 young (18-25 years), healthy comorbidity-free women with a body mass index (BMI) ≥27.5 kg/m(2) were recruited. Biochemical data were analysed using mean ± standard deviation or median (interquartile range) and multivariate modelling. Biochemical markers were also stratified according to varying degrees of overweight and obesity. Anaemia (haemoglobin <120 g/l) and iron deficiency (serum ferritin <15.0 µg/l) were prevalent in 10% and 17% of participants respectively. Mean/median soluble transferrin receptor was 1.61±0.44 mg/l; hepcidin 6.40 (7.85) ng/ml and C-reactive protein (CRP) 3.58 (5.81) mg/l. Multivariate modelling showed that BMI was a significant predictor of serum iron (coefficient = -0.379; standard error = 0.139; p = 0.008), transferrin saturation (coefficient = -0.588; standard error = 0.222; p = 0.009) and CRP (coefficient = 0.127; standard error = 0.024; p<0.001). Stratification of participants according to BMI showed those with ≥35.0 kg/m(2) had significantly higher CRP (p<0.001) than those in lower BMI categories. Increasing obesity was associated with minor disturbances in iron metabolism. However, overall outcomes indicated simple iron deficiency (hypoferritinaemia) was the primary iron-related abnormality with no apparent contribution of inflammation or hepcidin, even in those with BMI >35.0 kg/m(2). This indicates that obesity alone may not be sufficient to induce clinically significant disturbances to iron metabolism as previously described. This may be attributed to the lack of comorbidity in this cohort.
    PLoS ONE 07/2013; 8(7):e68675. DOI:10.1371/journal.pone.0068675 · 3.53 Impact Factor
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    ABSTRACT: Use of Global positioning system (GPS) technology in team sport permits measurement of player position, velocity, and movement patterns. GPS provides scope for better understanding of the specific and positional physiological demands of team sport and can be used to design training programs that adequately prepare athletes for competition with the aim of optimizing on-field performance. The objective of this study was to conduct a systematic review of the depth and scope of reported GPS and microtechnology measures used within individual sports in order to present the contemporary and emerging themes of GPS application within team sports. A systematic review of the application of GPS technology in team sports was conducted. We systematically searched electronic databases from earliest record to June 2012. Permutations of key words included GPS; male and female; age 12-50 years; able-bodied; and recreational to elite competitive team sports. The 35 manuscripts meeting the eligibility criteria included 1,276 participants (age 11.2-31.5 years; 95 % males; 53.8 % elite adult athletes). The majority of manuscripts reported on GPS use in various football codes: Australian football league (AFL; n = 8), soccer (n = 7), rugby union (n = 6), and rugby league (n = 6), with limited representation in other team sports: cricket (n = 3), hockey (n = 3), lacrosse (n = 1), and netball (n = 1). Of the included manuscripts, 34 (97 %) detailed work rate patterns such as distance, relative distance, speed, and accelerations, with only five (14.3 %) reporting on impact variables. Activity profiles characterizing positional play and competitive levels were also described. Work rate patterns were typically categoriszed into six speed zones, ranging from 0 to 36.0 km·h(-1), with descriptors ranging from walking to sprinting used to identify the type of activity mainly performed in each zone. With the exception of cricket, no standardized speed zones or definitions were observed within or between sports. Furthermore, speed zone criteria often varied widely within (e.g. zone 3 of AFL ranged from 7 to 16 km·h(-1)) and between sports (e.g. zone 3 of soccer ranged from 3.0 to <13 km·h(-1) code). Activity descriptors for a zone also varied widely between sports (e.g. zone 4 definitions ranged from jog, run, high velocity, to high-intensity run). Most manuscripts focused on the demands of higher intensity efforts (running and sprint) required by players. Body loads and impacts, also summarized into six zones, showed small variations in descriptions, with zone criteria based upon grading systems provided by GPS manufacturers. This systematic review highlights that GPS technology has been used more often across a range of football codes than across other team sports. Work rate pattern activities are most often reported, whilst impact data, which require the use of microtechnology sensors such as accelerometers, are least reported. There is a lack of consistency in the definition of speed zones and activity descriptors, both within and across team sports, thus underscoring the difficulties encountered in meaningful comparisons of the physiological demands both within and between team sports. A consensus on definitions of speed zones and activity descriptors within sports would facilitate direct comparison of the demands within the same sport. Meta-analysis from systematic review would also be supported. Standardization of speed zones between sports may not be feasible due to disparities in work rate pattern activities.
    06/2013; 43(10). DOI:10.1007/s40279-013-0069-2
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    ABSTRACT: Introduction: Young women are at risk of iron deficiency. Evidence suggests obesity and inflammation may further exacerbate this risk. This study aimed to investigate the strongest determinants of iron status in young, healthy overweight and obese women. Methods: Medical history, anthropometric (height, weight, waist) and biochemical (haemoglobin, transferrin saturation (Tsat), ferritin, soluble transferrin receptor (sTfR), sTfR/log ferritin (sTfR-F), hepcidin, C-reactive protein (CRP)) data were collected from 76 women (18-25y) with BMI >27.5kgm-2. Participants were genotyped for the rs855791 polymorphism of the TMPRSS6 gene known to be correlated with various iron markers. Associations were analysed using multiple linear regression. Data:mean±SD. Results: Mean age and BMI were 22.1±2.5y and 33.6±4.2kgm-2. 9.2% of participants were anaemic (Hb<120gL-1) with no cases of anaemia of inflammation (sTfR-F<1.0) detected. Hypoferritinaemia (<15µgL-1) and elevated sTfR (>2.39mgL-1) were identified in 17.1% and 5.3% respectively. Hepcidin (8.7±7.5ngmL-1) was significantly associated with ferritin (β=0.528; p<0.01), Tsat (β=0.295; p<0.01) and rs855791 (β=0.212; p=0.03). Inflammation was moderate (CRP: 6.0±7.5mgL-1), with 14.5% having clinically elevated CRP (>10mgL-1). Regression analysis using anthropometric and inflammatory variables, rs855791 and ethnicity, polycystic ovary syndrome and hormonal contraception as predictors showed contraception as the strongest predictor of serum iron, Tsat, sTfR and sTfR-F (all p<0.05). Conclusion: The most prevalent abnormality was hypoferritinaemia with no apparent contribution of inflammation or hepcidin to iron deficiency risk, suggesting aetiology of inadequate intake, absorption or high loss of iron. Hormonal contraceptive use was a significant factor influencing iron status across the cohort presumably as a result of reduced menstrual iron loss.
    20th European Congress on Obesity, Liverpool, UK; 05/2013
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    ABSTRACT: Aim: Limited research in young overweight and obese women indicates that they are difficult to recruit to weight management trials, with attrition higher and weight loss success lower than middle to older age participants. This study aimed to evaluate the effectiveness of different recruitment strategies for a clinical weight loss trial in overweight and obese Generation Y women. Methods: Overweight and obese (BMI >=27.5 kg/m-2) women aged 18-25 years (n=70) were required for a 12 month clinical weight management trial including diet, exercise and behaviour modification. Contact with researchers and eventual recruitment are reported for the various strategies employed to engage participants. Data reported as % or mean±SE. Results: Recruitment was challenging with only 50 of the total 70 participants recruited within the scheduled time frame (24 months). Just over one quarter (27%) of volunteers assessed were recruited. Flyers posted around local tertiary education campuses were the most successful method, yielding 36% of included participants. This was followed by advertisements on the local area health service intranet (26%) and in local and metropolitan newspapers (16%). Conclusions: Recruitment of overweight and obese Generation Y women for a clinical weight loss trial was difficult. Multiple strategies targeted at this age and gender group were required. Less rigorous selection criteria and reduced face-to-face intervention time may improve recruitment and retention rates into clinical trials for this age group.
    Asia Pacific Journal of Clinical Nutrition 01/2013; 22(2):235-40. · 1.36 Impact Factor

Publication Stats

382 Citations
121.75 Total Impact Points

Institutions

  • 2006–2014
    • University of Sydney
      • • Discipline of Exercise and Sport Science
      • • Faculty of Health Sciences
      Sydney, New South Wales, Australia
    • North Sydney Orthopaedic And Sports Medicine Centre
      Sydney, New South Wales, Australia
  • 2011
    • Qazvin University of Medical Sciences
      Kazvin, Qazvīn, Iran
  • 2009
    • University of the Sunshine Coast
      • School of Health and Sport Sciences
      Gold Coast, Queensland, Australia