Impact of High-intensity Interval Exercise and Moderate-Intensity Continuous Exercise on the Cardiac Troponin T Level at an Early Stage of Training

Summary

Here, we present protocols of high-intensity interval and moderate-intensity continuous exercise to observe the response of circulating cardiac troponin T (cTnT) concentration to acute exercise over 10 days. The information may assist with clinical interpretations of post-exercise cTnT elevation and guide the prescription of exercise.

Abstract

An elevation in cardiac troponin T (cTnT), as a highly specific biomarker of cardiomyocyte damage, after moderate-intensity continuous exercise (MCE) has been described. The exercise-induced cTnT response distorts the diagnostic role of the cTnT assay. Although high-intensity interval exercise (HIE) is growing in popularity and concerns remain about its safety, available data related to cTnT release after HIE is limited, which hampers the use of HIE as a health intervention. Here, we present three representative HIE protocols [traditional HIE (repeated 4 min cycling at 90% V̇O_2max interspersed with 3 min rest, 200 kJ/session); sprint interval exercise (SIE, repeated 1 min cycling at 120% V̇O_2max interspersed with 1.5 min rest, 200 kJ/session); and repeated sprint exercise (RSE, 40 x 6 s all-out sprints interspersed with 9 s rest)] and one representative MCE protocol (continuous cycling exercise at an intensity of 60% V̇O_2max, 200 kJ/session). Forty-seven sedentary, overweight young women were randomly assigned to one of four groups (HIE, SIE, RSE, and MCE). Six bouts of respective exercise were performed by every single group, with each being 48 h apart. Meanwhile, for four groups, the duration of the entire testing period was identical, being 10 days. Before and after the first and final exercise bouts, an assessment was conducted of cTnT. The current study provides a frame of reference giving a clear picture of how a specific exercise session affects the circulating cTnT concentration at the early stage of training. The information may assist with clinical interpretations of post-exercise cTnT elevation and guide the prescription of exercise, especially for HIE.

Introduction

The benefits of regular exercise on the heart are well-documented¹. However, the risk of cardiac events, such as acute myocardial infarction (AMI), transiently increases during an intense exercise^2,3. Individuals with low levels of regular physical activity show higher risk towards AMI^2,3. Cardiac troponin T (cTnT) is the biochemical gold standard in the diagnosis of AMI⁴. However, there is a burgeoning evidence that the cTnT is elevated after continuous prolonged exercise, which undoubtedly distorts the ....

Protocol

The protocol (No. 31771319) was approved by the Hebei Normal University Review Board and conformed to the Declaration of Helsinki. All participants provided written informed consent before participating in the testing described.

1. Participant Screening and Preparation for the Experiment

1. For recruitment, ensure that the participants satisfy the following inclusion criteria: aged between 18 and 25, a minimum body mass index (BMI) of 23 kg/m, which is the overweight cut-off for Asian adults¹⁰, consistent body weight (± 2 kg) for the most recent three months, no exercise training or regular physical activiti....

Results

All participants (n = 47) completed the study, and no adverse cardiac events (e.g., chest pain and sign of myocardial ischemia on ECG) were found during testing in the four groups. As expected, the acute exercise heart rate (HR) data, including HR_mean and %HR_max, at the 1ST assessment is similar (all P > 0.05) to those in the 6TH assessment in all four groups. Further, the HR data in the RSE and MCE groups is the highest and lowest among the four groups, respectively, but is similar betw.......

Discussion

The repetitive short to long bouts of rather high-intensity exercise interspersed with recovery periods are involved in HIE, which is subdivided into traditional HIE (“near maximal” efforts) and SIE (“supramaximal” efforts), using a common classification scheme⁶. In addition, RSE is a particularly intense form of SIE, where the activity is “all-out” but only lasts for 3 to 7 s⁶. To the best of our knowledge, this is the first integrated s.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Cobas E 601 analyser	Roche Diagnostics, Penzberg, Germany		Used for measuring the circulating cardiac troponin T concentration
Monark 839E Stress Testing Cycle Ergometer	Monark Exercise AB, Vansbro, Sweden		Used for all exercise protocols except repeated sprint exercise
Monark 894E Wingate Testing Cycle Ergometer	Monark Exercise AB, Vansbro, Sweden		Only used for repeated sprint exercise protocol
Quark-PFT-ergo Metabolic Analyser	Cosmed, Rome, Italy	C09072-02-99
SPSS Statistics 20.0 software package	IBM Corp., Armonk, USA
Zephyr BioHarness 3.0	Zephyr Technology, Auckland, New Zealand	9800.0189/9600.0190	Electrocardiograph Monitor