List of Titles

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.
Full Text: false
Reviewed:
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.

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
Full Text: false
Reviewed:
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.

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
Full Text: false
Reviewed:
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.

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