The Application of Maximal Heart Rate Predictive Equations in Hypoxic Conditions

Gallagher, Carla Amanda, Willems, Mark E. T., Lewis, Mark P. and Myers, Stephen D. (2015) The Application of Maximal Heart Rate Predictive Equations in Hypoxic Conditions. European Journal of Applied Physiology, 115 (2). pp. 277-284. ISSN 1439-6319

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Abstract

PURPOSE:
Peak heart rate (HRpeak) is a common tool used in exercise prescription for groups in which maximal exercise intensity is contraindicated; however, the application of this method in normobaric hypoxia is unknown. Therefore, this study investigated the response of HRpeak and the application of predictive HRpeak equations to prescribe exercise intensity in acute normobaric hypoxia. Results were used to examine whether age-derived HRpeak predictive equations are valid in hypoxic conditions.

METHODS:
Fifteen untrained (eight men) volunteers (age 22 ± 2 years; peak rate of oxygen consumption 46.3 ± 7.0 ml kg(-1) min(-1)) completed incremental cycle ergometer tests (randomised order) to measure HRpeak at sea-level (SL (ambient inspiratory oxygen fraction (FIO2) 0.209)) and four normobaric hypoxic conditions FIO2: 0.185, 0.165, 0.142, 0.125 (≈1,000-4,000 m).

RESULTS:
HRpeak was similar across all conditions (SL, 182 ± 13; 0.185, 178 ± 11; 0.165, 177 ± 9; 0.142, 178 ± 9; 0.125, 175 ± 10 b min(-1)) despite a reduction in oxygen saturation with increasing hypoxia (SL, 95 ± 5; 0.185, 95 ± 2; 0.165, 92 ± 2; 0.142, 88 ± 3; 0.125, 82 ± 4 %; P ≤ 0.05). The HRpeak was overestimated by all equations compared to the measured value (P < 0.05). Four equations overestimated HRpeak in all conditions (P < 0.01); two in four conditions (0.185, 0.165, 0.142, 0.125; P < 0.01); and two in three conditions (0.165, 0.142, 0.125; P < 0.01).

CONCLUSION:
The overestimation of HRpeak by commonly used age-derived predictive equations in normobaric hypoxic conditions suggests that despite possible contraindications researchers should directly measure HRpeak whenever possible if it is to be used to prescribe exercise intensities.

Item Type: Article
Uncontrolled Keywords: Normobaric hypoxia, Exercise prescription, Exercise intensity, Cycle ergometry
Subjects: Q Science > QM Human anatomy
Q Science > QP Physiology
Divisions: Departments > Sport and Exercise Sciences
Depositing User: Carla Rue
Date Deposited: 15 Mar 2019 09:33
Last Modified: 15 Mar 2019 09:33
URI: http://eprints.chi.ac.uk/id/eprint/4489

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