Open AccessRate dependent influence of arterial desaturation on self-selected exercise intensity during cycling
Author(s) -
Saro D. Farra,
Stephen S. Cheung,
Scott Thomas,
Ira Jacobs
Publication year - 2017
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0171119
Subject(s) - heart rate , cycling , medicine , time trial , perceived exertion , cycle ergometer , intensity (physics) , exercise intensity , cardiology , exercise physiology , oxygen saturation , blood pressure , zoology , anesthesia , oxygen , chemistry , physics , biology , archaeology , organic chemistry , quantum mechanics , history
The purpose of this study was to clarify if Ratings of Perceived Exertion (RPE) and self-selected exercise intensity are sensitive not only to alterations in the absolute level of arterial saturation (S P O 2 ) but also the rate of change in S P O 2 . Twelve healthy participants (31.6 ± 3.9 y, 175.5 ± 7.7 cm, 73.3 ± 10.3 kg, 51 ± 7 mL·kg -1 ·min -1V ˙ O 2 peak) exercised four times on a cycle ergometer, freely adjusting power output (PO) to maintain RPE at 5 on Borg’s 10-point scale with no external feedback to indicate their exercise intensity. The fraction of inspired oxygen (F I O 2 ) was reduced during three of those trials such that S P O 2 decreased during exercise from starting values (>98%) to 70%. These trials were differentiated by the time over which the desaturation occurred: 3.9 ± 1.4 min, -8.7 ± 4.2%•min -1 (FAST), 11.0 ± 3.7 min, -2.8 ± 1.3%•min -1 (MED), and 19.5 ± 5.8 min, -1.5 ± 0.8%•min -1 (SLOW) (P < 0.001). Compared to stable PO throughout the control condition (no S P O 2 manipulation), PO significantly decreased across the experimental conditions (FAST = 2.8 ± 2.1 W•% S P O 2 -1 ; MED = 2.5 ± 1.8 W•% S P O 2 -1 ; SLOW = 1.8 ± 1.6 W•% S P O 2 -1 ; P < 0.001). The rates of decline in PO during FAST and MED were similar, with both greater than SLOW. Our results confirm that decreases in absolute S P O 2 impair exercise performance and that a faster rate of oxygen desaturation magnifies that impairment.