title: Cardiovascular responses to static exercise in boys: insights from tissue Doppler imaging.
abstract: Ventricular functional changes and mechanisms of the cardiovascular responses during static exercise have not been well delineated in children. In this study, Doppler echocardiographic techniques were utilized to assess cardiovascular adaptations to bilateral isometric leg extension at 30% maximal voluntary contraction for three minutes in a group of 14 healthy boys (mean age 10.2 +/- 1.5 years). Mean heart rate rose from 77 +/- 9 to 106 +/- 11 bpm, stroke volume fell from 59 +/- 9 to 52 +/- 7 ml, and cardiac output increased from 4.58 +/- 0.58 to 5.62 +/- 0.81 l min(-1) (P < 0.05). Mean arterial pressure rose from 86 +/- 7 to 109 +/- 9 mm Hg, with no significant change in peripheral vascular resistance. By tissue Doppler imaging markers, inotropic function improved by 59%, while lusitropic function increased 38%. These findings suggest that (1) cardiovascular responses to static leg extension in boys are similar to those in adult men, and (2) isometric leg extension triggers modest increases in both systolic and diastolic function.
authors.affiliation: Department of Pediatrics, Baystate Medical Center, Springfield, MA 01106, USA. Thomas.rowland@bhs.org
authors.forename: Thomas
authors.initials: T
authors.lastname: Rowland
authors.forename: Kevin
authors.initials: K
authors.lastname: Heffernan
authors.forename: Sae Young
authors.initials: SY
authors.lastname: Jae
authors.forename: George
authors.initials: G
authors.lastname: Echols
authors.forename: Gary
authors.initials: G
authors.lastname: Krull
authors.forename: Bo
authors.initials: B
authors.lastname: Fernhall
mesh_terms: D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology*; D002648:Child; D015150:Echocardiography, Doppler; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology; D013318:Stroke Volume / Q000502:physiology*; D014655:Vascular Resistance / Q000502:physiology; D016276:Ventricular Function