title: Influence of exercise intensity and duration on functional and biochemical perturbations in the human heart.
abstract: Strenuous endurance exercise induces transient functional and biochemical cardiac perturbations that persist for 24-48 h. The magnitude and time-course of exercise-induced reductions in ventricular function and increases in cardiac injury markers are influenced by the intensity and duration of exercise. In a human experimental model, exercise-induced reductions in ventricular strain and increases in cardiac troponin are greater, and persist for longer, when exercise is performed within the heavy- compared to moderate-intensity exercise domain, despite matching for total mechanical work. The results of the present study help us better understand the dose-response relationship between endurance exercise and acute cardiac stress/injury, a finding that has implications for the prescription of day-to-day endurance exercise regimes.
  
  
  
  Strenuous endurance exercise induces transient cardiac perturbations with ambiguous health outcomes. The present 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 years; V̇O2, peak : 4.0 ± 0.8 l min(-1) ) before, throughout (50%, 75% and 100%), and during recovery (1, 3, 6 and 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.
authors.affiliation: Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia.
authors.forename: Glenn M
authors.initials: GM
authors.lastname: Stewart
authors.affiliation: Department of Cardiology, Fujita Health University, Nagoya, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Yamada
authors.affiliation: Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia.
authors.forename: Luke J
authors.initials: LJ
authors.lastname: Haseler
authors.affiliation: Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia.
authors.forename: Justin J
authors.initials: JJ
authors.lastname: Kavanagh
authors.affiliation: Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia.|Cardiology Division, The Prince Charles Hospital, Brisbane, Australia.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Chan
authors.affiliation: Faculty of Education, Science, Technology and Maths, University of Canberra, Canberra, Australia.
authors.forename: Gus
authors.initials: G
authors.lastname: Koerbin
authors.affiliation: Pathology North, Royal North Shore Hospital, Sydney, Australia.
authors.forename: Cameron
authors.initials: C
authors.lastname: Wood
authors.affiliation: Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia.
authors.forename: Surendran
authors.initials: S
authors.lastname: Sabapathy
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D001696:Biomechanical Phenomena / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002097:C-Reactive Protein / Q000378:metabolism*; D002302:Cardiac Output / Q000502:physiology; D004452:Echocardiography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods*; D006321:Heart / Q000502:physiology*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D011897:Random Allocation; D013318:Stroke Volume / Q000502:physiology; D013997:Time Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein; D006854:Hydrocortisone