The effect of exercise training on metaboreflex regulation of heart rate and blood pressure

  • Author / Creator
    Reinhart, Chance W.
  • The metaboreflex is a cardiovascular reflex which activates the sympathetic nervous system when a mismatch between oxygen delivery and demand occurs during exercise; metabolic by-products accumulate in the interstitium of skeletal muscle tissue and stimulate afferent nerve fibers. This in turn elevates heart rate and blood pressure by increasing cardiac output as well as peripheral vasoconstriction. This thesis investigated the effects of exercise training on metaboreflex regulation of heart rate and blood pressure during dynamic exercise in healthy humans. It was hypothesized that activation of the metaboreflex would produce a smaller increase in heart rate and blood pressure during exercise following aerobic exercise training. Young males (age=24.7±3.9) were assigned to traditional aerobic (n=10) or sprint interval (SPRI n=15) exercise training on a cycle ergometer. The traditional aerobic training group trained five days/week for six weeks at a workload that elicited 75% of maximum heart rate for a flywheel distance of 16 km. The sprint interval training group performed repeats of 30 s bouts of exercise at a resistance equal to 7.5% of the subject’s body weight on three days/week for six weeks. Each exercise bout was separated by 4.5 minutes of cycling with minimal resistance to allow for recovery. Young males performed steady-state recumbent cycling exercise at 60% of maximum heart rate in control and partial flow-restricted conditions before and after traditional aerobic and sprint interval exercise training. Once heart rate achieved steady-state, pneumatic leg cuffs were inflated to partially restrict leg blood flow during exercise and stimulate the metaboreflex. Heart rate and blood pressure were measured continuously measured via finger-cuff photo-plethysmography. Traditional aerobic and sprint interval exercise training both improved aerobic fitness (PRE: TRAD-50.3±10.6 mL/kg/min., SPRI-48.7±9.5 kg/mL/min.; POST: TRAD-53.5±8.0 mL/kg/min., SPRI-50.3±8.4 mL/kg/min.) and peak power output (PRE: TRAD-305±35W., SPRI-289±52 W; POST: TRAD-325±33 W L/min., SPRI-312±52 W). However, neither traditional aerobic nor sprint interval exercise training altered the heart rate and mean arterial pressure response to metaboreflex activation in either the exercise trained legs (ΔHR - PRE:TRAD- 7.7±4.9 bpm, SPRI- 7.4±5.8 bpm; POST: TRAD- 6.9±3.3 bpm, SPRI- 7.2±3.4 bpm)(ΔMAP- PRE: TRAD- 11.1±6.0 mmHg, SPRI- 7.3±5.6 mmHg; POST: TRAD- 12.1±6.7 mmHg, SPRI - 8.9±4.3 mmHg) or the untrained forearm (ΔHR- PRE: TRAD- 0.4±10.7 bpm, SPRI- -2.3±8.4 bpm; POST: TRAD- -3.2±9.7 bpm, SPRI- -2.51±9.8 mmHg)(ΔMAP - PRE: TRAD- 18.3±13.2 mmHg, SPRI- 23.3±10.5 mmHg; POST: TRAD- 15.3±14.0 mmHg, SPRI- 23.5±9.1 mmHg). In conclusion, exercise training did not alter the magnitude of the heart rate and blood pressure response to metaboreflex activation during exercise in healthy young males.

  • Subjects / Keywords
  • Graduation date
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
    • Physical Education and Recreation
  • Supervisor / co-supervisor and their department(s)
    • Darren S. DeLorey (Physical Education and Recreation / Rehabilitation Medicine)
  • Examining committee members and their departments
    • Michael Kennedy (Physical Education and Recreation)
    • Craig Steinback (Physical Education and Recreation)