AUTHOR=Tam Enrico , Bruseghini Paolo , Capelli Carlo , Oliboni Eugenio , Pezzato Andrea , Pogliaghi Silvia , Pozzi Mucelli Roberto , Schena Federico , Calabria Elisa 

TITLE=Effect of Endurance and Strength Training on the Slow Component of O2 Kinetics in Elderly Humans

JOURNAL=Frontiers in Physiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2018.01353

DOI=10.3389/fphys.2018.01353

ISSN=1664-042X

ABSTRACT=<p>We compared the effects of 8 weeks of high intensity, aerobic interval training (<italic>HIT)</italic> and isoinertial resistance training (<italic>IRT)</italic> on: (i) <inline-graphic xlink:href="fphys-09-01353-i001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" /><italic>O</italic><sub>2</sub> kinetics during heavy (<italic>HiEx</italic>) intensity exercise and; (ii) work economy during moderate (<italic>ModEx</italic>) intensity exercise in 12 healthy elderly men (69.3 ± 4.2 years). Breath-by-breath <inline-graphic xlink:href="fphys-09-01353-i001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" /><italic>O</italic><sub>2</sub> and muscle deoxygenation ([<italic>HHb</italic>] by means of <italic>NIRS</italic>) were measured in <italic>HiEx</italic> and <italic>ModEx</italic> at identical workloads before and after trainings. In <italic>HiEx</italic>, <inline-graphic xlink:href="fphys-09-01353-i001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" /><italic>O</italic><sub>2</sub> and <italic>HHb</italic> responses were modeled as tri-exponential and mono-exponential increasing functions, respectively. A two-way ANOVA for repeated measures analysis was made; Effect size (η<sup>2</sup>) was also evaluated. After <italic>HIT</italic> the amplitude and the time delay of the slow component of <italic>O<sub>2</sub></italic> uptake (<inline-graphic xlink:href="fphys-09-01353-i001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" /><italic>O</italic><sub>2sc</sub>) during <italic>HiEx</italic> were smaller (−32%; <italic>P</italic> = 0.045) and longer (+19.5%; <italic>P</italic> = 0.001), respectively. At <italic>Post IRT</italic>: (i) during <italic>ModEx, gain</italic> was lower (−5%; <italic>P</italic> = 0.050); (ii) during <italic>HiEx</italic>, τ<sub>2</sub> (+14.4%; <italic>P</italic> = 0.050), <italic>d<sub>3</sub></italic> (+8.6%; <italic>P</italic> = 0.050), and τ<sub>3</sub> (+17.2%; <italic>P</italic> = 0.050) were longer than at <italic>Pre IRT</italic>. After <italic>HIT</italic>, the decrease of the <inline-graphic xlink:href="fphys-09-01353-i001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" /><italic>O</italic><sub>2sc</sub> amplitude was likely induced by the beneficial effects of training on a more responsive <italic>O</italic><sub>2</sub> delivery and consumption cascade leading to a better muscle metabolic stability. <italic>IRT</italic> training was able to increase exercise economy during <italic>ModEx</italic> and to reduce the amplitude and delay the onset of <inline-graphic xlink:href="fphys-09-01353-i001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" /><italic>O</italic><sub>2sc</sub> during <italic>HiEx</italic>. These effects should be due to the reduction and the delayed recruitment of Type II muscle fibers. The better exercise economy and the delayed appearance of <inline-graphic xlink:href="fphys-09-01353-i001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" /><italic>O</italic><sub>2sc</sub> induced by <italic>IRT</italic> suggests that strength training might be included in endurance training programs to improve exercise economy and resistance to fatigue in this population of old subjects.</p>