Luke J Haseler

Griffith University, Southport, Queensland, Australia

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Publications (53)162.77 Total impact

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    ABSTRACT: Strenuous endurance exercise induces transient cardiac perturbations with ambiguous health outcomes. This study investigated the magnitude and time-course of exercise-induced functional and biochemical cardiac perturbations by manipulating the exercise intensity-duration matrix. Echocardiograph-derived left (LV) and right (RV) ventricular global longitudinal strain (GLS), and serum high-sensitivity cardiac troponin (hs-cTnI) concentration, were examined in 10 males (Age: 27 ± 4 yr; VO2peak : 4.0 ± 0.8 L·min(-1) ) before, throughout (50-, 75- & 100-%), and during recovery (1-, 3-, 6- & 24-h) from two exercise trials. The two exercise trials consisted of 90 and 120 min of heavy- and moderate-intensity cycling, respectively, with total mechanical work matched. LVGLS decreased (P < 0.01) during the 90-min trial only, with reductions peaking at 1-h post (pre: -19.9 ± 0.6; 1-h post: -18.5 ± 0.7%) and persisting for >24-h into recovery. RVGLS decreased (P < 0.05) during both exercise trials with reductions in the 90-min trial peaking at 1-h post (pre: -27.5 ± 0.7%; 1-h post: -25.1 ± 0.8%) and persisting for >24-h into recovery. Serum hs-cTnI increased (P < 0.01) during both exercise trials with concentrations peaking at 3-h post, but only exceeding cardio-healthy reference limits (14 ng L(-1) ) in the 90-min trial (pre: 4.2 ± 2.4 ng L(-1) ; 3-h post: 25.1 ± 7.9 ng L(-1) ). Exercise-induced reductions in ventricular strain and increases in cardiac injury markers persist for 24 h following exercise that is typical of day-to-day endurance exercise training; however, the magnitude and time-course of this response can be altered by manipulating the intensity-duration matrix. This article is protected by copyright. All rights reserved.
    No preview · Article · Jan 2016 · The Journal of Physiology
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    ABSTRACT: Polygenic profiling has been proposed for elite endurance performance, using an additive model determining the proportion of optimal alleles in endurance athletes. To investigate this model's utility for elite triathletes, we genotyped seven polymorphisms previously associated with an endurance polygenic profile (ACE Ins/Del, ACTN3 Arg577Ter, AMPD1 Gln12Ter, CKMM 1170bp/985+185bp, HFE His63Asp, GDF8 Lys153Arg and PPARGC1A Gly482Ser) in a cohort of 196 elite athletes who participated in the 2008 Kona Ironman championship triathlon. Mean performance time (PT) was not significantly different in individual marker analysis. Age, sex, and continent of origin had a significant influence on PT and were adjusted for. Only the AMPD1 endurance-optimal Gln allele was found to be significantly associated with an improvement in PT (model p = 5.79 x 10-17, AMPD1 genotype p = 0.01). Individual genotypes were combined into a total genotype score (TGS); TGS distribution ranged from 28.6 to 92.9, concordant with prior studies in endurance athletes (mean±SD: 60.75±12.95). TGS distribution was shifted toward higher TGS in the top 10% of athletes, though the mean TGS was not significantly different (p = 0.164) and not significantly associated with PT even when adjusted for age, sex, and origin. Receiver operating characteristic curve analysis determined that TGS alone could not significantly predict athlete finishing time with discriminating sensitivity and specificity for three outcomes (less than median PT, less than mean PT, or in the top 10%), though models with the age, sex, continent of origin, and either TGS or AMPD1 genotype could. These results suggest three things: that more sophisticated genetic models may be necessary to accurately predict athlete finishing time in endurance events; that non-genetic factors such as training are hugely influential and should be included in genetic analyses to prevent confounding; and that large collaborations may be necessary to obtain sufficient sample sizes for powerful and complex analyses of endurance performance.
    Preview · Article · Dec 2015 · PLoS ONE
  • B Balmain · G M Stewart · A Yamada · J Chan · L J Haseler · S Sabapathy
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    ABSTRACT: The effects of isometric handgrip exercise (IHG) coupled with a period of post-exercise circulatory occlusion (OCC) - known to sustain exercise-induced increases in blood pressure while facilitating a decrease in heart rate - on left ventricular (LV) twist mechanics was examined. Two-dimensional speckle-tracking echocardiography was used to assess LV apical and basal rotation, and LV twist in 19 healthy participants (23±2 yr) at rest, during 3-min of IHG (performed at 40% maximum voluntary contraction), and 3-min of OCC immediately following IHG. IHG elicited significant (p<0.001) increases in mean arterial pressure (Rest: 91±1, IHG: 122±2 mmHg) and heart rate (Rest: 65±2, IHG: 91±4 beats min(-1) ). Mean arterial pressure remained elevated (116±2 mmHg; p<0.001 vs. Rest), while heart rate returned to resting levels (68±3 beats min(-1) ; P = 0.159 vs. Rest), during OCC. Apical rotation decreased significantly (p<0.01) by 10±5% during IHG and 21±4% during OCC, while basal rotation remained unchanged from rest. LV twist decreased from rest to IHG (12±5%; P = 0.015) and OCC (21±4%; P = 0.001), while a decrease in LV un-twist rate was observed only during OCC. An increase in blood pressure generated by IHG, and maintained by a period of OCC, impairs aspects of LV twist mechanics. OCC isolated the effect of the arterial blood pressure rise (from heart rate), magnifying the impairment of LV twist mechanics when compared to IHG, whilst also negatively impacting LV relaxation. We propose that a protocol utilising isometric exercise followed by circulatory occlusion provides a method for studying the effects of blood pressure changes on LV twist mechanics. This article is protected by copyright. All rights reserved.
    No preview · Article · Oct 2015 · Experimental physiology
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    ABSTRACT: Left ventricular (LV) twist mechanics are routinely assessed via echocardiography in clinical and research trials investigating the function of obliquely oriented myocardial fibers. However, echocardiograph-derived measures of LV twist may be compromised by nonstandardized acquisition of the apical image. This study examined the reproducibility of echocardiograph-derived parameters of apical twist mechanics at multiple levels of the apical myocardium. Two sets of 2D LV parasternal short-axis images were obtained in 30 healthy subjects (24 men; 19-57 year) via echocardiography. Images were acquired immediately distal to the papillary muscles (apical image 1), immediately above the point of LV cavity obliteration at end systole (apical image 3), and midway between apical image 1 and apical image 3 (apical image 2). Repeat scans were performed within 1 hour, and twist mechanics (rotation and rotation rate) were calculated via frame-by-frame tracking of natural acoustic echocardiographic markers (speckle tracking). The magnitude of apical rotation increased progressively toward the apex (apical image 1: 4.2 ± 2.1°, apical image 2: 7.2 ± 3.9°, apical image 3: 11.8 ± 4.6°). apical images 1, 2, and 3 each had moderate to good correlations between repeat scans (ICC: 0.531-0.856). When apical images 1, 2, and 3 were averaged, rotation was 7.7 ± 2.7° and between-scan correlation was excellent (ICC: 0.910). Similar results were observed for systolic and diastolic rotation rates. Averaging multiple standardized apical images, tending progressively toward the apex, generated the most reproducible rotation indices and may be optimal for the assessment of LV twist mechanics across therapeutic, interventional, and research studies; however, care should be taken given the influence of acquisition level on the magnitude of apical rotation. © 2015, Wiley Periodicals, Inc.
    Full-text · Article · Aug 2015 · Echocardiography
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    ABSTRACT: Transient reductions in myocardial strain coupled with cardiac-specific biomarker release have been reported following prolonged exercise (>180min). However, it is unknown if: a) shorter duration exercise (60min) can perturb cardiac function; or b) if exercise-induced reductions in strain are masked by hemodynamic changes that are associated with passive recovery from exercise. Left (LV) and right ventricular (RV) global longitudinal strain (GLS), LV torsion (LVT), and high-sensitivity cardiac troponin (hs-cTnT) were measured in fifteen competitive cyclists (Age: 28±3 yr; VO2peak: 4.8±0.6 L•min-1) before and after a 60-min high-intensity cycling race intervention (CRIT60). At both time points (pre- and post-CRIT60) strain and torsion were assessed at rest and during a standardized low-intensity exercise challenge (power output: 96±8 W) in a semi-recumbent position using echocardiography. During rest, hemodynamic conditions were different from pre- to post-CRIT60 (MAP: 96±1 vs 86±2 mmHg, p<0.001) and there were no changes in strain or torsion. In contrast, during the standardized low-intensity exercise challenge hemodynamic conditions were unchanged from pre- to post-CRIT60 (MAP: 98±1 vs 97±1 mmHg, ns), but strain decreased (LVGLS: -20.3±0.5% vs -18.5±0.4%, p<0.01; RVGLS: -26.4±1.6% vs -22.4±1.5%, p<0.05), while LVT remained unchanged. Serum hs-cTnT increased by 345% after the CRIT¬60 (6.0±0.6 vs 20.7±6.9 ng⋅(L-1), p<0.05). This study demonstrates that exercise-induced functional and biochemical cardiac perturbations are not confined to ultra-endurance sporting events, and transpire during exercise that is typical of day-to-day training undertaken by endurance athletes. The clinical significance of cumulative exposure to endurance exercise warrants further study. Copyright © 2014, American Journal of Physiology - Heart and Circulatory Physiology.
    Full-text · Article · Jan 2015 · AJP Heart and Circulatory Physiology
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    ABSTRACT: Background: Longitudinal strain (LS) is a quantitative parameter that adds incremental value to wall motion analysis. The aim of this study was to compare the reproducibility of LS derived from Doppler tissue imaging and speckle-tracking between an expert and a novice strain reader during dobutamine stress echocardiography (DSE). Methods: Forty-one patients (mean age, 65 ± 15 years; mean ejection fraction, 58 ± 11%) underwent DSE per clinical protocol. Global LS derived from speckle-tracking and regional LS derived from both speckle-tracking and Doppler tissue imaging were measured twice by an expert strain reader and also measured twice by a novice strain reader. Intraobserver and interobserver analyses were performed using intraclass correlation coefficients (ICC), Bland-Altman analysis, and absolute difference values (mean ± SD). Results: Global LS measured by the expert strain reader demonstrated high intraobserver measurement reproducibility (rest: ICC = 0.95, absolute difference = 5.5 ± 4.9%; low dose: ICC = 0.96, absolute difference = 5.7 ± 3.7%; peak dose: ICC = 0.87, absolute difference = 11.4 ± 8.4%). Global LS measured by the novice strain reader also demonstrated high intraobserver reproducibility (rest: ICC = 0.97, absolute difference = 4.1 ± 3.4%; low dose: ICC = 0.94, absolute difference = 5.4 ± 5.9%; peak dose: ICC = 0.94, absolute difference = 6.1 ± 4.8%). Global LS also showed high interobserver agreement between the expert and novice readers at all stages of DSE (rest: ICC = 0.90, absolute difference = 8.5 ± 7.5%; low dose: ICC = 0.90, absolute difference = 8.9 ± 7.1%; peak dose: ICC = 0.87, absolute difference = 10.8 ± 8.4%). Of all parameters studied, LS derived from Doppler tissue imaging had relatively low interobserver and intraobserver agreement. Conclusions: Global LS is highly reproducible during all stages of DSE. This variable is a potentially reliable and reproducible measure of myocardial deformation.
    No preview · Article · May 2014 · Journal of the American Society of Echocardiography: official publication of the American Society of Echocardiography
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    ABSTRACT: Background Longitudinal strain (LS) is a quantitative parameter that adds incremental value to wall motion analysis. The aim of this study was to compare the reproducibility of LS derived from Doppler tissue imaging and speckle-tracking between an expert and a novice strain reader during dobutamine stress echocardiography (DSE). Methods Forty-one patients (mean age, 65 ± 15 years; mean ejection fraction, 58 ± 11%) underwent DSE per clinical protocol. Global LS derived from speckle-tracking and regional LS derived from both speckle-tracking and Doppler tissue imaging were measured twice by an expert strain reader and also measured twice by a novice strain reader. Intraobserver and interobserver analyses were performed using intraclass correlation coefficients (ICC), Bland-Altman analysis, and absolute difference values (mean ± SD). Results Global LS measured by the expert strain reader demonstrated high intraobserver measurement reproducibility (rest: ICC = 0.95, absolute difference = 5.5 ± 4.9%; low dose: ICC = 0.96, absolute difference = 5.7 ± 3.7%; peak dose: ICC = 0.87, absolute difference = 11.4 ± 8.4%). Global LS measured by the novice strain reader also demonstrated high intraobserver reproducibility (rest: ICC = 0.97, absolute difference = 4.1 ± 3.4%; low dose: ICC = 0.94, absolute difference = 5.4 ± 5.9%; peak dose: ICC = 0.94, absolute difference = 6.1 ± 4.8%). Global LS also showed high interobserver agreement between the expert and novice readers at all stages of DSE (rest: ICC = 0.90, absolute difference = 8.5 ± 7.5%; low dose: ICC = 0.90, absolute difference = 8.9 ± 7.1%; peak dose: ICC = 0.87, absolute difference = 10.8 ± 8.4%). Of all parameters studied, LS derived from Doppler tissue imaging had relatively low interobserver and intraobserver agreement. Conclusions Global LS is highly reproducible during all stages of DSE. This variable is a potentially reliable and reproducible measure of myocardial deformation.
    No preview · Article · Jan 2014
  • A. Yamada · K. Sugimoto · K. Takada · K. Shiino · Y. Ozaki · L. Haseler · J. Chan

    No preview · Article · Dec 2013 · Heart, Lung and Circulation

  • No preview · Article · Dec 2013 · Heart, Lung and Circulation
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    Full-text · Article · Dec 2013 · Heart, Lung and Circulation
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    ABSTRACT: The aim of this study was to determine whether global strains derived from three-dimensional (3D) speckle-tracking echocardiography (STE) are as accurate as left ventricular (LV) ejection fraction (LVEF) obtained by two-dimensional (2D) and 3D echocardiography in the quantification of LV function. Two-dimensional and 3D echocardiography and 2D and 3D STE were performed in 88 patients (LVEF range, 17%-79%). Two-dimensional and 3D global longitudinal strain (GLS), global circumferential strain (GCS), global radial strain, and global area strain were quantified and correlated with LV function determined by 2D and 3D echocardiographic LVEF. Reproducibility, feasibility, and duration of study to perform 3D STE were assessed by independent, blinded observers. A total of 78 patients (89%) underwent 3D STE. All 3D speckle-tracking echocardiographic parameters had strong correlations with assessment of LV function determined by 2D and 3D echocardiographic LVEF. Three-dimensional GCS was the best marker of LV function (r = -0.89, P < .0001). Subgroup analysis demonstrated that 3D speckle-tracking echocardiographic parameters were particularly useful in identifying LV dysfunction (LVEF < 50%). Receiver operating characteristic curve analysis demonstrated areas under the curve of 0.97 for 3D GCS, 0.96 for 3D global radial strain, 0.95 for 3D global area strain, and 0.87 for 3D GLS. An optimal 3D GCS cutoff value of magnitude < -12% predicted LV dysfunction (LVEF obtained by 2D echocardiography < 50%) with 92% sensitivity and 90% specificity. There was good correlation between 2D GLS and 3D GLS (r = 0.85, P < .001; mean difference, -1.7 ± 6.5%). Good intraobserver, interobserver, and test-retest agreements were seen with 3D STE. Time for image acquisition to postprocessing analysis was significantly reduced with 3D STE (3.7 ± 1.0 minutes) compared with 2D STE (4.6 ± 1.5 min) (P < .05). Global strain by 3D STE is a promising novel alternative to quantitatively assess LV function. Three-dimensional STE is reproducible, feasible, and time efficient.
    No preview · Article · Dec 2013 · Journal of the American Society of Echocardiography: official publication of the American Society of Echocardiography
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    ABSTRACT: Re-programming of gene expression is fundamental for skeletal muscle adaptations in response to endurance exercise. This study investigated the time-course dependent changes in the muscular transcriptome following an endurance exercise trial consisting of 1 h of intense cycling immediately followed by 1 h of intense running. Skeletal muscle samples were taken at baseline, 3 h, 48 h, and 96 h post-exercise from eight healthy, endurance-trained, male individuals. RNA was extracted from muscle. Differential gene expression was evaluated using Illumina microarrays and validated with qPCR. Gene set enrichment analysis identified enriched molecular signatures chosen from the Molecular Signatures Database. Three h post-exercise, 102 gene sets were up-regulated [family wise error rate (FWER), P < 0.05]; including groups of genes related with leukocyte migration, immune and chaperone activation, and cyclic AMP responsive element binding protein (CREB) 1-signaling. Forty-eight h post-exercise, among 19 enriched gene sets (FWER, P < 0.05), two gene sets related to actin cytoskeleton remodeling were up-regulated. Ninety-six h post-exercise, 83 gene sets were enriched (FWER, P < 0.05), 80 of which were up-regulated; including gene groups related to chemokine signaling, cell stress management, and extracellular matrix remodeling. These data provide comprehensive insights into the molecular pathways involved in acute stress, recovery, and adaptive muscular responses to endurance exercise. The novel 96 h post-exercise transcriptome indicates substantial transcriptional activity, potentially associated with the prolonged presence of leukocytes in the muscles. This suggests that muscular recovery, from a transcriptional perspective, is incomplete 96 h after endurance exercise involving muscle damage.
    Full-text · Article · Dec 2013 · Journal of Applied Physiology
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    ABSTRACT: Although phosphorus magnetic resonance spectroscopy ((31)P-MRS) based evidence suggests that in vivo peak mitochondrial respiration rate in young untrained adults is limited by the intrinsic mitochondrial capacity of ATP synthesis, it remains unknown whether a large, locally targeted, increase in convective O2 delivery would alter this interpretation. Consequently, we examined the effect of superimposing reactive hyperaemia (RH), induced by a period of brief ischemia during the last min of exercise, on oxygen delivery and mitochondrial function in the calf muscle of 9 young adults in comparison to free-flow conditions (FF). To this aim, we used an integrative experimental approach combining (31)P-MRS, Doppler ultrasound imaging, and near-infrared spectroscopy. Limb blood flow [area under the curve (AUC), 1.4±0.8 L in FF and 2.5±0.3 L in RH, P<0.01] and convective O2 delivery (AUC, 0.30±0.16 L in FF and 0.54±0.05 L in RH, P<0.01) were significantly increased in RH in comparison to FF. RH was also associated with significantly higher capillary blood flow (P<0.05) and faster tissue re-oxygenation mean response times (70±15 s in FF and 24±15 s in RH, P<0.05). This resulted in a 43% increase in estimated peak mitochondrial ATP synthesis rate (29±13 mM.min(-1) in FF and 41±14 mM.min(-1) in RH, P<0.05) whereas the phosphocreatine (PCr) recovery time constant in RH was not significantly different (P=0.22). This comprehensive assessment of local skeletal muscle O2 availability and utilization in untrained subjects reveals that mitochondrial function, assessed in vivo by (31)P-MRS, is limited by convective O2 delivery rather than an intrinsic mitochondrial limitation.
    Full-text · Article · Jun 2013 · Journal of Applied Physiology
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    ABSTRACT: Aim: Short-term exercise training may induce metabolic and performance adaptations before any changes in mitochondrial enzyme potential. However, there has not been a study that has directly assessed changes in mitochondrial oxidative capacity or metabolic control as a consequence of such training in vivo. Therefore, we used (31) P-magnetic resonance spectroscopy ((31) P-MRS) to examine the effect of short-term plantar flexion exercise training on phosphocreatine (PCr) recovery kinetics and the control of respiration rate. Method: To this aim, we investigated 12 healthy men, experienced with this exercise modality (TRA), and 7 time-control subjects (TC). Results: After 5 days of training, maximum work rate during incremental plantar flexion exercise was significantly improved (P < 0.01). During the recovery period, the maximal rate of oxidative adenosine triphosphate synthesis (PRE: 28 ± 13 mm min(-1) ; POST: 26 ± 15 mm min(-1) ) and the PCr recovery time constant (PRE: 31 ± 19 s; POST: 29 ± 16) were not significantly altered. In contrast, the Hill coefficient (nH ) describing the co-operativity between respiration rate and ADP was significantly increased in TRA (PRE: nH = 2.7 ± 1.4; POST: nH = 3.4 ± 1.9, P < 0.05). Meanwhile, there were no systematic variations in any of these variables in TC. Conclusion: This study reveals that 5 days of training induces rapid adaptation in the allosteric control of respiration rate by ADP before any substantial improvement in muscle oxidative capacity occurs.
    No preview · Article · Apr 2013 · Acta Physiologica
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    ABSTRACT: Neutrophils serve as an intriguing model for the study of innate immune cellular activity induced by physiological stress. We measured changes in the transcriptome of circulating neutrophils following an experimental exercise trial (EXTRI) consisting of 1 hour (h) of intense cycling immediately followed by 1 h of intense running. Blood samples were taken at baseline, 3 h, 48 h, and 96 h post-EXTRI from eight healthy, endurance-trained, male subjects. RNA was extracted from isolated neutrophils. Differential gene expression was evaluated using Illumina microarrays, and validated with qPCR. Gene set enrichment analysis identified enriched molecular signatures chosen from the Molecular Signatures Database. Blood concentrations of muscle damage indices, neutrophils, interleukin (IL)-6 and IL-10 were increased (P<0.05) 3 h post-EXTRI. Up-regulated groups of functionally related genes 3 h post-EXTRI included gene sets associated with the recognition of tissue damage, the IL-1 receptor-, and toll-like receptor (TLR) pathways (FWER p-value<0.05). The core enrichment for these pathways included TLRs, low-affinity immunoglobulin receptors, S100 calcium binding protein A12, and negative regulators of innate immunity, e.g. IL-1 receptor antagonist, and IL-1 receptor associated kinase-3. Plasma myoglobin changes correlated with neutrophil TLR4 gene expression (r=0.74; P<0.05). Neutrophils had returned to their non-activated state 48 h post-EXTRI, indicating that their initial pro-inflammatory response was transient and rapidly counter-regulated. This study provides novel insight into the signaling mechanisms underlying the neutrophil responses to endurance exercise, suggesting that their transcriptional activity was particularly induced by damage-associated molecule patterns, hypothetically originating from the leakage of muscle components into the circulation.
    Full-text · Article · Apr 2013 · Journal of Applied Physiology

  • No preview · Article · Dec 2012 · Heart, Lung and Circulation

  • No preview · Article · Dec 2012 · Heart, Lung and Circulation

  • No preview · Article · Dec 2012 · Heart, Lung and Circulation

  • No preview · Article · Dec 2012 · Heart, Lung and Circulation
  • B. Budiono · L. See Hoe · J. Peart · K. Ashton · L. Haseler · J. Headrick

    No preview · Article · Dec 2012 · Journal of Science and Medicine in Sport

Publication Stats

622 Citations
162.77 Total Impact Points

Institutions

  • 2004-2015
    • Griffith University
      • • School of Rehabilitation Sciences
      • • Heart Foundation Research Centre
      Southport, Queensland, Australia
  • 1999-2004
    • University of California, San Diego
      • Department of Medicine
      San Diego, CA, United States