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CARDIOVASCULAR RESPONSES TO A THREE WEEK LOW-VOLUME HIGH-INTENSITY CYCLING PROTOCOL

B Sirikul

Abstract

Bovorn Sirikul. Southeastern Louisiana University, Hammond, LA.

BACKGROUND: High-intensity interval training (HIIT) has shown promise as an effective replacement for traditional longer-duration moderate exercise due to the considerably lower time commitment, but additional evidence is needed to determine how little exercise is enough to elicit improvements in cardiorespiratory fitness. It was hypothesized that significant increases in VO2max would be observed after ten sessions of the 2x3 protocol. Thus, the purpose of this study was to examine the cardiorespiratory responses using this protocol in healthy, sedentary individuals. METHODS: Fourteen participants completed baseline oxygen consumption (VO2max) testing using a cycle ergometer. Heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP), VO2, respiratory exchange ratio (RER), and rate of perceived exertion (RPE) were measured. Pulse pressure and rate pressure product (RPP) were calculated from the observed values. Exercise intervention trials began 48 hours after the completion of baseline testing. The protocol was three weeks long consisting of three sessions lasting ~14 minutes each week. Each session consisted of a warm-up, followed by two 3-min sub-maximal high-intensity cycling intervals at 85-90% of VO2max at rates of 50-100 rpm with two minutes of low-intensity (50-60% VO2max) recovery between and a cool-down after the second interval. RESULTS: No significant changes were observed for maximal graded exercise test HR, peak RER, maximal DBP, or time to exhaustion. However, VO2peak increased from 31.79 ± 1.14 ml*kg-1*min-1 pre-intervention, to 35.89 ± 1.81 ml*kg-1*min-1 post-intervention, resulting in a significant improvement (p=0.012). Significant increases were also observed in maximal SBP (158 ± 5.5 mmHg to 174.43 ± 9.28 mmHg; p=0.030), as well as RPP at HR max (288.20 ± 11.65 bpm to 314.48 ± 16.38 bpm; p=0.043). CONCLUSIONS: The employed low-volume high-intensity protocol period did elicit a significant improvement in VO2peak as has been shown in a number of previous HIIT studies. Since the 14-minute protocol was well tolerated by participants, the findings of this study demonstrated the potential of a low-volume high-intensity cycling protocol to increase exercise adherence due to its short duration and sub-maximal nature. This project was partially supported by the Kenelly Family Endowed Professorship.

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