List of Titles

Accuracy of heart rate watches: Implications for weight management

- Wallen, Matthew, Gomersall, Sjaan, Keating, Shelley, Wisløff, Og Ulrik, Coombes, Jeff

Authors: Wallen, Matthew , Gomersall, Sjaan , Keating, Shelley , Wisløff, Og Ulrik , Coombes, Jeff
Date: 2016
Type: Text , Journal article
Relation: PLoS ONE Vol. 11, no. 5 (2016), p.
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Description: Background: Wrist-worn monitors claim to provide accurate measures of heart rate and energy expenditure. People wishing to lose weight use these devices to monitor energy balance, however the accuracy of these devices to measure such parameters has not been established. Aim: To determine the accuracy of four wrist-worn devices (Apple Watch, Fitbit Charge HR, Samsung Gear S and Mio Alpha) to measure heart rate and energy expenditure at rest and during exercise. Methods: Twenty-two healthy volunteers (50% female; aged 24 ± 5.6 years) completed ∼1-hr protocols involving supine and seated rest, walking and running on a treadmill and cycling on an ergometer. Data from the devices collected during the protocol were compared with reference methods: electrocardiography (heart rate) and indirect calorimetry (energy expenditure). Results: None of the devices performed significantly better overall, however heart rate was consistently more accurate than energy expenditure across all four devices. Correlations between the devices and reference methods were moderate to strong for heart rate (0.67-0.95 [0.35 to 0.98]) and weak to strong for energy expenditure (0.16-0.86 [-0.25 to 0.95]). All devices underestimated both outcomes compared to reference methods. The percentage error for heart rate was small across the devices (range: 1-9%) but greater for energy expenditure (9-43%). Similarly, limits of agreement were considerably narrower for heart rate (ranging from -27.3 to 13.1 bpm) than energy expenditure (ranging from -266.7 to 65.7 kcals) across devices. Conclusion: These devices accurately measure heart rate. However, estimates of energy expenditure are poor and would have implications for people using these devices for weight loss. © 2016 Wallen et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Assessment of the five-minute oxygen uptake efficiency slope in children with obesity

- Dias, Katrin, Masterson, Concetta, Wallen, Matthew, Tjonna, Arnt, Hosseini, Mansoureh, Davies, Peter, Cain, Peter, Leong, Gary, Arena, Ross, Ingul, Charlotte, Coombes, Jeff

Authors: Dias, Katrin , Masterson, Concetta , Wallen, Matthew , Tjonna, Arnt , Hosseini, Mansoureh , Davies, Peter , Cain, Peter , Leong, Gary , Arena, Ross , Ingul, Charlotte , Coombes, Jeff
Date: 2017
Type: Text , Journal article
Relation: Pediatric Exercise Science Vol. 29, no. 3 (2017), p. 350-360
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Description: PURPOSE: Poor cardiorespiratory fitness is associated with increased all cause morbidity and mortality. In children with obesity, maximum oxygen uptake (VO2max) may not be achieved due to reduced motivation and peripheral fatigue. We aimed to identify a valid submaximal surrogate for VO2max in children with obesity. METHODS: Ninety-two children with obesity (7-16 years) completed a maximal exercise treadmill test and entered a three-month exercise and/or nutrition intervention after which the exercise test was repeated (n=63). Participants were required to reach VO2max to be included in this analysis (n=32 at baseline and n=13 at both time-points). The oxygen uptake efficiency slope (OUES) was determined as the slope of the line when VO2 (L/min) was plotted against logVE. Associations between the maximal OUES, submaximal OUES (at 3, 4, 5 and 6 minutes of the exercise test) and VO2max were calculated. RESULTS: In the cross-sectional analysis, VO2max (L/min) was strongly correlated with 5-min OUES independent of Tanner puberty stage and sex (R2=0.80, P<0.001). Longitudinal changes in VO2max were closely reflected by changes in 5-min OUES independent of change in percent body fat (R2=0.63, P<0.05). CONCLUSIONS: The 5-min OUES is a viable alternative to VO2max when assessing children with obesity.

High-intensity interval training and cardiac autonomic control in individuals with metabolic syndrome: A randomised trial

- Ramos, Joyce, Dalleck, Lance, Borrani, Fabio, Beetham, Kassia, Mielke, Gregore, Dias, Katrin, Wallen, Matthew, Keating, Shelley, Fassett, Robert, Coombes, Jeff

Authors: Ramos, Joyce , Dalleck, Lance , Borrani, Fabio , Beetham, Kassia , Mielke, Gregore , Dias, Katrin , Wallen, Matthew , Keating, Shelley , Fassett, Robert , Coombes, Jeff
Date: 2017
Type: Text , Journal article
Relation: International Journal of Cardiology Vol. , no. (2017), p.
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Description: Background: Insulin resistance has been postulated to play a central role in the co-appearance of various cardiovascular disease risk factors constituting the metabolic syndrome (MetS). There is evidence that altered cardiac autonomic function (CAF) may precede the onset of insulin resistance. Exercise training has been shown to improve CAF in different populations, yet little is known regarding the exercise dose response for CAF. The aim of this study was to investigate the impact of different volumes of high-intensity interval training (HIIT) and traditional moderate-intensity continuous training (MICT) on CAF in participants with MetS. Methods: Individuals with MetS (n=56) were randomised into the following 16-week training interventions: i) MICT (n=16, 30min at 60-70%HRpeak, 5×/week); ii) 4HIIT (n=19, 4×4min bouts at 85-95%HRpeak, interspersed with 3min of active recovery at 50-70%HRpeak, 3×/week); or iii) 1HIIT (n=21, 1×4min bout at 85-95%HRpeak, 3×/week). R-R interval recorded for 5min in a supine position at pre- and post-intervention was used to derive linear (SDNN, RMSSD, pNN50, LF, HF, LF/HF) and non-linear (SD1, SD2, Alpha1, Alpha2, SampEn) heart rate variability (HRV) indices as measures of CAF. Group×time interaction effects were examined (ANCOVA) and Eta squared (η2) interaction effect sizes calculated. Results: While there were no significant between-group differences in CAF indices, there were small-to-medium group×time interaction effects on SDNN [F(2,52)=0.70, p=0.50, η2 =0.02], RMSSD [F(2,52)=1.35, p=0.27, η2 =0.03], HF power [F(2,52)=1.27, p=0.29, η2 =0.03], SD1 [F(2,52)=0.47, p=0.63, η2 =0.01], and SD2 [F(2,52)=0.41, p=0.67, η2 =0.01]. The following represent the relative percentage increases across these variables for 4HIIT, MICT, and 1HIIT respectively (SDNN, +30%, +17%, 9%; RMSSD, +30%, +22%, -2%; HF power, +69%, +18%, +7%; SD1, +30%, +22%,-2%; SD2, +22%, +14%, 4%). Conclusions: There were no significant between-group differences for the effects of exercise dose on CAF indices, however; high-volume HIIT demonstrated the greatest magnitude of effect for improving CAF in individuals with MetS. © 2017 Elsevier Ireland Ltd.

Impact of beta-blockers on cardiopulmonary exercise testingin patients with advanced liver disease

- Wallen, Matthew, Hall, Adrian, Dias, Katrin, Ramos, Joyce, Keating, Shelley, Woodward, Aidan, Skinner, Tina, Macdonald, Graeme, Arena, Ross, Coombes, Jeff

Authors: Wallen, Matthew , Hall, Adrian , Dias, Katrin , Ramos, Joyce , Keating, Shelley , Woodward, Aidan , Skinner, Tina , Macdonald, Graeme , Arena, Ross , Coombes, Jeff
Date: 2017
Type: Text , Journal article
Relation: Alimentary Pharmacology and Therapeutics Vol. , no. (2017), p. 1-7
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Description: Summary Background: Patients with advanced liver disease may develop portal hypertensionthat can result in variceal haemorrhage. Beta-blockers reduce portal pressure andminimise haemorrhage risk. These medications may attenuate measures of car-diopulmonary performance, such as the ventilatory threshold and peak oxygenuptake measured via cardiopulmonary exercise testing. Aim: To determine the effect of beta-blockers on cardiopulmonary exercise testingvariables in patients with advanced liver disease. Methods: This was a cross-sectional analysis of 72 participants who completed acardiopulmonary exercise test before liver transplantation. All participants remainedon their usual beta-blocker dose and timing prior to the test. Variables measuredduring cardiopulmonary exercise testing included the ventilatory threshold, peakoxygen uptake, heart rate, oxygen pulse, the oxygen uptake efficiency slope and theventilatory equivalents for carbon dioxide slope. Results: Participants taking beta-blockers (n = 28) had a lower ventilatory threshold(P <.01) and peak oxygen uptake (P = .02), compared to participants not takingbeta-blockers. After adjusting for age, the model of end-stage liver-disease score,liver-disease aetiology, presence of refractory ascites and ventilatory thresholdremained significantly lower in the beta-blocker group (P = .04). The oxygen uptakeefficiency slope was not impacted by beta-blocker use. Conclusions: Ventilatory threshold is reduced in patients with advanced liver dis-ease taking beta-blockers compared to those not taking the medication. This mayincorrectly risk stratify patients on beta-blockers and has implications for patientmanagement before and after liver transplantation. The oxygen uptake efficiencyslope was not influenced by beta-blockers and may therefore be a better measureof cardiopulmonary performance in this patient population.

Low-volume high intensity interval training is sufficient to ameliorate the severity of the metabolic syndrome

- Ramos, Joyce, Dalleck, Lance, Borrani, Fabio, Beetham, Kassia, Wallen, Matthew, Mallard, Alistair, Clark, Bronwyn, Gomersall, Sjaan, Keating, Shelley, Fassett, Robert, Coombes, Jeff

Authors: Ramos, Joyce , Dalleck, Lance , Borrani, Fabio , Beetham, Kassia , Wallen, Matthew , Mallard, Alistair , Clark, Bronwyn , Gomersall, Sjaan , Keating, Shelley , Fassett, Robert , Coombes, Jeff
Date: 2017
Type: Text , Journal article
Relation: Metabolic Syndrome and Related Disorders Vol. 15, no. 7 (2017), p. 319-328
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Description: BACKGROUND: High-intensity interval training (HIIT) is superior to moderate-intensity continuous training (MICT) at improving cardiometabolic risk. However, the optimal volume of HIIT to reduce the severity of the metabolic syndrome (MetS) has yet to be investigated. The aim of this study was to examine the impact of different volumes of HIIT and MICT on MetS severity (MetS z-score). METHODS: This was a substudy of the "Exercise in prevention of Metabolic Syndrome" (EX-MET) multicenter trial, reporting data collected at the Brisbane site. Ninety-nine adults diagnosed with MetS were randomized to one of the following 16-week interventions: (1) MICT [n = 34, 30 min at 60%-70% heart rate (HR) peak/session, 150 min/week]; (2) 4HIIT (n = 34, 4 × 4 min bouts at 85%-95% HR peak, interspersed with 3 min active recovery at 50%-70% HR peak, 114 min/week); or (3) 1HIIT (n = 31, 1 × 4 min bout at 85%-95% HR peak, 51 min/week). Z-scores were derived from levels of MetS risk factors before and after the intervention. RESULTS: Eighty-one participants completed post-testing (MICT, n = 26; 4HIIT, n = 28, 1HIIT, n = 27). After excluding 16 participants who had a change in medication dosage or type during the intervention, a total of 65 participants were included in the analysis [MICT, n = 22, age 55 ± 10 years, body mass index (BMI) 32 ± 6 kg/m; 4HIIT, n = 22, 56 ± 10 years, 35 ± 9 kg/m2; 1HIIT, n = 21, 57 ± 8 years, 32 ± 5 kg/m). MetS severity reduced following all interventions (pre- to post-MetS z-score: MICT, 1.80 ± 1.93 to 0.90 ± 1.93; 4HIIT, 2.75 ± 2.56 to 2.17 ± 2.71; 1HIIT, 2.48 ± 3.38 to 0.84 ± 2.98), with no significant differences between groups. There were no reported adverse events that were directly related to the exercise interventions. CONCLUSIONS: Low-volume HIIT (51 min/week) was as effective as high-volume HIIT (114 min/week) and MICT (150 min/week) in ameliorating MetS severity.

NAFLD in clinical practice : Can simple blood and anthropometric markers be used to detect change in liver fat measured by 1H-MRS?

- Keating, Shelley, Parker, Helen, Hickman, Ingrid, Gomersall, Sjaan, Wallen, Matthew, Coombes, Jeff, Macdonald, Graeme, George, Jacob, Johnson, Nathan

Authors: Keating, Shelley , Parker, Helen , Hickman, Ingrid , Gomersall, Sjaan , Wallen, Matthew , Coombes, Jeff , Macdonald, Graeme , George, Jacob , Johnson, Nathan
Date: 2017
Type: Text , Journal article
Relation: Liver International Vol. 37, no. 12 (2017), p.1907-1915
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Description: Background & Aims: Research in NAFLD management is commonly based on quantitative assessment of liver fat by proton-magnetic resonance spectroscopy (1H-MRS), and translation of this into clinical practice is currently limited by availability and expense. Novel steatosis biomarkers have been proposed for the prediction of liver fatness; however, whether these are suitable for detecting changes in liver fat is unknown. We aimed to determine the accuracy of these indices, and waist circumference (WC), in quantifying longitudinal change in 1H-MRS-quantified liver fat. Methods: We performed a secondary analysis using data from 97 overweight/obese adults (age: 39.7±11.5 years, body mass index: 30.7±4.4 kg/m2, liver fat: 6.0±4.8%, 65% male) who completed either an 8-week exercise or 12-week nutraceutical intervention, with varying degrees of change in liver fat. Baseline and post-intervention measures were liver fat (1H-MRS), NAFLD Liver Fat Score, Liver Fat Equation (LFE), Fatty Liver Index (FLI), Hepatic Steatosis Index (HSI), the Visceral Adiposity Index (VAI) and WC. Results: Only the change in HSI, FLI and WC was associated with change in liver fat; however, correlations were weak to moderate. There was no agreement between the LFE and 1H-MRS for detecting liver fat change. Only change in WC significantly affected change in liver fat (P<.001), and WC AUROC for the presence of steatosis was 0.65 and 0.78 for men and women respectively.Conclusions: Novel indices are limited in their ability to detect longitudinal change in liver fat. Waist circumference may offer modest utility as a surrogate to infer liver fat change with lifestyle interventions.
Description: Background & Aims: Research in NAFLD management is commonly based on quantitative assessment of liver fat by proton-magnetic resonance spectroscopy (1H-MRS), and translation of this into clinical practice is currently limited by availability and expense. Novel steatosis biomarkers have been proposed for the prediction of liver fatness; however, whether these are suitable for detecting changes in liver fat is unknown. We aimed to determine the accuracy of these indices, and waist circumference (WC), in quantifying longitudinal change in 1H-MRS-quantified liver fat. Methods: We performed a secondary analysis using data from 97 overweight/obese adults (age: 39.7±11.5 years, body mass index: 30.7±4.4 kg/m2, liver fat: 6.0±4.8%, 65% male) who completed either an 8-week exercise or 12-week nutraceutical intervention, with varying degrees of change in liver fat. Baseline and post-intervention measures were liver fat (1H-MRS), NAFLD Liver Fat Score, Liver Fat Equation (LFE), Fatty Liver Index (FLI), Hepatic Steatosis Index (HSI), the Visceral Adiposity Index (VAI) and WC. Results: Only the change in HSI, FLI and WC was associated with change in liver fat; however, correlations were weak to moderate. There was no agreement between the LFE and 1H-MRS for detecting liver fat change. Only change in WC significantly affected change in liver fat (

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Poor cardiorespiratory fitness is a risk factor for sepsis in patients awaiting liver transplantation

- Wallen, Matthew, Woodward, Aidan, Hall, Adrian, Skinner, Tina, Coombes, Jeff, Macdonald, Graeme

Authors: Wallen, Matthew , Woodward, Aidan , Hall, Adrian , Skinner, Tina , Coombes, Jeff , Macdonald, Graeme
Date: 2019
Type: Text , Journal article
Relation: Transplantation Vol. , no. 103(3) (2019), p.529-535
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Description: Background Patients with advanced liver disease are at increased risk of infection and other complications. A significant proportion of patients also have poor fitness and low muscle mass. The primary aim of this study was to investigate if cardiorespiratory fitness and body composition are risk factors for sepsis and other complications of advanced liver disease. Methods Patients being listed for liver transplantation underwent cardiopulmonary exercise testing to determine ventilatory threshold (VT). Computed tomography was used to measure skeletal muscle and subcutaneous and visceral adipose tissue indexes. All unplanned hospital admissions, deaths or delistings prior to transplantation were recorded. Results Eighty-two patients [aged 55.1 (50.6–59.4) years, median (interquartile range); male 87%] achieved a median VT of 11.7 (9.7–13.4) mL[BULLET OPERATOR]kg-1[BULLET OPERATOR]min-1. Their median MELD-Na score was 18 (14–22); and 37 had hepatocellular carcinoma. There were 50 admissions in 31 patients; with 16 admissions for sepsis in 13 patients. Patients with sepsis had a significantly lower VT [sepsis 9.5 (7.8–11.9), no sepsis 11.8 (10.5–13.8) mL[BULLET OPERATOR]kg-1[BULLET OPERATOR]min-1; P=0.003]. No body composition variables correlated with sepsis, nor were there any significant associations between VT and unplanned admissions for other indications. Multivariate logistic regression demonstrated that VT was independently associated with a diagnosis of sepsis (P=0.03). Poisson regression revealed that VT was a significant predictor for the number of septic episodes (P=0.02); independent of age, MELD-Na score, hepatocellular carcinoma diagnosis, presence of ascites, and beta-blocker use. Conclusion Poor cardiorespiratory fitness is an independent risk factor for the development of sepsis in advanced liver disease.

Safety, adherence and efficacy of exercise training in solid-organ transplant candidates: A systematic review

- Wallen, Matthew, Skinner, Tina, Pavey, Toby, Hall, Adrian, Macdonald, Graeme, Coombes, Jeff

Authors: Wallen, Matthew , Skinner, Tina , Pavey, Toby , Hall, Adrian , Macdonald, Graeme , Coombes, Jeff
Date: 2016
Type: Text , Journal article
Relation: Transplantation Reviews Vol. 30, no. 4 (2016), p. 218-226
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Description: Background Patients awaiting solid-organ transplantation may be encouraged to undertake exercise training to improve pre- and post-transplant outcomes. However, the safety, adherence and efficacy of exercise training in this population remain unclear. Methods All randomized, non-randomized and non-controlled trials of exercise training interventions in solid-organ transplant candidates were included. The Cochrane risk of bias tool and a modified Newcastle–Ottawa scale were used to assess procedural quality. Safety was defined as the number of reported adverse events during exercise training. Adherence was evaluated from session attendance, and efficacy as changes in cardiorespiratory fitness (CRF), exercise capacity, muscular strength, health-related quality of life (HR-QoL) and lung function. Results Eleven studies involving 874 patients were included: four randomized controlled, one non-randomized controlled and six non-controlled trials. Six studies included heart transplant candidates and five involved patients awaiting lung transplantation. Three trials included aerobic-only training, one incorporated resistance-only exercise and seven combined modalities. Twelve adverse events were reported with four due to exercise, although methods to collect these data were often omitted. Exercise adherence ranged from 82.5% to 100%, but was poorly described. No significant between-group changes attributable to exercise training were demonstrated. However, significant within-group improvements in CRF, exercise capacity, muscular strength, lung function and HR-QoL were observed. Conclusions Patients awaiting heart or lung transplant appear to tolerate exercise training despite the larger number of adverse events compared to other high-risk populations. Exercise training demonstrated within-group benefits for several outcomes, with no significant between-group differences. Randomized controlled trials with sufficient statistical power are required for all solid-organ transplant candidates. © 2016 Elsevier Inc.

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