Moderate Intensity Intermittent Exercise Modality May Prevent Cardiovascular Drift.

Muzaffer Colakoglu,Gorkem Balci,Ozgur Ozkaya

doi:10.3390/sports6030098

Abstract

Cardiovascular drift (CV-Drift) may occur after the ~10th min of submaximal continuous exercising. The purpose of this study was to examine whether CV-Drift is prevented by an intermittent exercise modality, instead of a continuous exercise. Seven well-trained male cyclists volunteered to take part in the study (O2max: 61.7 ± 6.13 mL·min−1·kg−1). Following familiarization sessions, athletes’ individual maximal O2 consumption (O2max), maximum stroke volume responses (SVmax), and cardiac outputs (Qc) were evaluated by a nitrous-oxide re-breathing system and its gas analyzer. Then, continuous exercises were performed 30 min at cyclists’ 60% O2max, while intermittent exercises consisted of three 10 min with 1:0.5 workout/recovery ratios at the same intensity. Qc measurements were taken at the 5th, 9th, 12nd, 15th, 20th, 25th, and 30th min of continuous exercises versus 5th and 10th min of workout phases of intermittent exercise modality. Greater than a 5% SV decrement, with accompanying HR, increase, while Qc remained stable and was accepted as CV-Drift criterion. It was demonstrated that there were greater SV responses throughout intermittent exercises when compared to continuous exercises (138.9 ± 17.9 vs. 144.5 ± 14.6 mL, respectively; p ≤ 0.05) and less HR responses (140.1 ± 14.8 vs. 135.2 ± 11.6 bpm, respectively; p ≤ 0.05), while mean Qc responses were similar (19.4 ± 2.1 vs. 19.4 ± 1.5 L, respectively; p > 0.05). Moreover, the mean times spent at peak SV scores of exercise sessions were greater during intermittent exercise (1.5 vs. 10 min) (p < 0.001). In conclusion, intermittent exercises reduce CV-Drift risk and increases cardiac adaptation potentials of exercises with less physiological stress.

Highlights

Cardiovascular drift (CV-Drift) is characterized by a gradual decrease in stroke volume (SV) and an increase in heart rate (HR), whereas cardiac output (Qc) remains stable without an increase in exercise intensity
Main results showed that a clear CV-Drift characterized by progressively decrease in SV and parallel increase in HR, whereas Qc was maintained nearly constant and occurred during continuous exercises for all participants
The main outcomes of this study may be reviewed as (i) there was a greater CV-Drift pattern observed in continuous exercises, CV-Drift effects minimized by intermittent exercise modality; (ii) intermittent exercises provided greater SV responses throughout the workload periods

Summary

Introduction

Cardiovascular drift (CV-Drift) is characterized by a gradual decrease in stroke volume (SV) and an increase in heart rate (HR), whereas cardiac output (Qc) remains stable without an increase in exercise intensity. CV-Drift usually appears after 10th min of constant load prolonged heavy and very heavy exercises [1,2]. These intensities corresponded between aerobic threshold and slightly above the anaerobic threshold [2,3]. CV-Drift occurs due to SV decrement in warm environmental conditions based on a progressive increase in cutaneous blood flow, as body temperature and dehydration rise [4]. Drift reveals by a second HR increase after an exercise-induce HR increment based on catecholamine rise in thermo-neutral conditions [4,5]. If exercise duration is several hours and noticeable dehydration becomes apparent, cardiac output would decline even in a thermo-neutral environment [6]. Drift-time and their depths are closely related with the exercise intensity, duration, modality, and activated muscle proportion, etc. [7,8,9]

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