Effects of heavy-intensity priming exercise on pulmonary oxygen uptake kinetics and muscle oxygenation in heart failure with preserved ejection fraction

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2019-03, Vol.316 (3), p.R199-R209
• Main Authors: Boyes, Natasha G, Eckstein, Janine, Pylypchuk, Stephen, Marciniuk, Darcy D, Butcher, Scotty J, Lahti, Dana S, Dewa, Dalisizwe M K, Haykowsky, Mark J, Wells, Calvin R, Tomczak, Corey R
• Format: Article
• Language: English
• Subjects: Aged; Bicycling; Capillaries - metabolism; Congestive heart failure; Cycles; Deoxygenation; Ejection fraction; Exercise; Female; Heart failure; Heart Failure - metabolism; Heart Failure - physiopathology; Heart Rate; Humans; Infrared spectra; Infrared spectroscopy; Intolerance; Kinetics; Lung - metabolism; Male; Microvasculature; Middle Aged; Mitochondria; Muscle, Skeletal - metabolism; Muscle, Skeletal - physiopathology; Muscles; Near infrared radiation; Older people; Oxygen; Oxygen Consumption; Oxygen uptake; Oxygenation; Physical training; Priming; Pulmonary Gas Exchange; Pulmonary Ventilation; Spectroscopy, Near-Infrared; Steady state; Stroke Volume; Time constant; Vascular Resistance
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00290.2018

Exercise intolerance is a hallmark feature in heart failure with preserved ejection fraction (HFpEF). Prior heavy exercise ("priming exercise") speeds pulmonary oxygen uptake (V̇o ) kinetics in older adults through increased muscle oxygen delivery and/or alterations in mitochondrial metabolic activity. We tested the hypothesis that priming exercise would speed V̇o on-kinetics in patients with HFpEF because of acute improvements in muscle oxygen delivery. Seven patients with HFpEF performed three bouts of two exercise transitions: MOD1, rest to 4-min moderate-intensity cycling and MOD2, MOD1 preceded by heavy-intensity cycling. V̇o , heart rate (HR), total peripheral resistance (TPR), and vastus lateralis tissue oxygenation index (TOI; near-infrared spectroscopy) were measured, interpolated, time-aligned, and averaged. V̇o and HR were monoexponentially curve-fitted. TPR and TOI levels were analyzed as repeated measures between pretransition baseline, minimum value, and steady state. Significance was P < 0.05. Time constant (τ; tau) V̇o (MOD1 49 ± 16 s) was significantly faster after priming (41 ± 14 s; P = 0.002), and the effective HR τ was slower following priming (41 ± 27 vs. 51 ± 32 s; P = 0.025). TPR in both conditions decreased from baseline to minimum TPR ( P < 0.001), increased from minimum to steady state ( P = 0.041) but remained below baseline throughout ( P = 0.001). Priming increased baseline ( P = 0.003) and minimum TOI ( P = 0.002) and decreased the TOI muscle deoxygenation overshoot ( P = 0.041). Priming may speed the slow V̇o on-kinetics in HFpEF and increase muscle oxygen delivery (TOI) at the onset of and throughout exercise. Microvascular muscle oxygen delivery may limit exercise tolerance in HFpEF.