This work was supported by the National Natural Science Foundation of China (Grant No. 31771319).

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
<ol>
	<li>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 (&#177; 2 kg) for the most recent three months, no exercise training or regular physical activities, no record of hormonal, orthopaedic or cardiovascular diseases, diabetes, hyperlipidaemia, hypertension or polycystic ovary syndrome, as well as, no current use of prescribed medications (including contraceptive pills) and no history of smoking.</li>
	<li>Randomly assign 47 eligible participants to one of the following four groups: traditional HIE (n = 12), sprint interval exercise (SIE, n = 11), repeated sprint exercise (RSE, n = 12) or MCE (n = 12) group.</li>
	<li>Adjust and record the appropriate seat height on the cycling ergometers so that the participant pedals with a slight knee bend (~10&#176;) at full downstroke of the pedal.</li>
	<li>Instruct the participants to perform two initial exercise sessions (as described in step 3) to familiarize them with the respective type of cycling exercise (HIE, SIE, RSE or MCE).</li>
</ol>
2. Experimental Procedures
<ol>
	<li>First, instruct each participant to perform a continuous incremental test on a stress testing cycle ergometer to assess maximal oxygen uptake (V&#775;O2max).
	<ol>
		<li>Warm up for 5 min at 25 W. Then start the test by performing continuous 2 min stages (20 W increment per stage) starting at 50 W with a pedal frequency of 60 rpm until volitional exhaustion.</li>
		<li>Use a breath-by-breath metabolic analyzer to measure the oxygen consumption during the exercise.</li>
		<li>Calculate the V&#775;O2max based on the highest 30 s average value. Then, calculate a power output that elicits 60%, 90% and 120% V&#775;O2max in the MCE, HIE and SIE groups, respectively, using the equation of linear regression through plotting the steady state V&#775;O2 versus power output11.</li>
	</ol>
	</li>
	<li>At least 5 days after pre-intervention assessments, instruct the HIE, SIE, RSE and MCE groups to commence their respective training. 
	NOTE: Start all exercise tests at the same time of the day (e.g., 11:00 A.M.). Meanwhile, ensure that the tests are conducted in a laboratory with temperature and humidity-controlled settings (20 &#176;C and 50% relative humidity). Ask all participants to stick to both their daily activities and eating habits throughout the experiment.
	<ol>
		<li>Instruct the participant to refrain from any strenuous exercise for 48 h, after a routine warm-up, instruct the HIE, SIE, RSE and MCE groups to engage in their respective exercise session on a cycle ergometer as arranged. Perform the exercise protocol as detailed in step 3.</li>
		<li>Perform 6 exercise sessions carried out over a time span of 10 days for all four groups. Select the 1st (1ST) and 6th (6TH) exercise sessions to observe the cTnT response to the acute exercise (Figure 1).</li>
	</ol>
	</li>
</ol>
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/60252/60252fig01.jpg" /> 
Figure 1: Schematic diagram of study procedures.&#160;HIE = high-intensity interval exercise; SIE = sprint interval exercise; RSE = repeated sprint exercise; MCE = moderate-intensity continuous exercise. <a href="https://www.jove.com/files/ftp_upload/60252/60252fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="4">
	<li>Record a continuous electrocardiogram (ECG) during exercise via a portable electrocardiograph (ECG) monitor.</li>
	<li>Draw venous blood samples before and immediately after exercise, as well as 3 h and 4 h after the selected exercise session to assess the serum cTnT. With the subjects in a seated position, draw 5 mL of venous blood from the antecubital vein for each sample. 
	NOTE: Post-exercise blood samples timings conformed to our prior work, which demonstrated that blood cTnT concentrations reached their peak 3 or 4 h following acute exercise in a laboratory-based study12.</li>
	<li>For the separation of the serum, allow the blood to clot at room temperature. Centrifuge the blood samples at 3,500 x g for 20 min.</li>
	<li>Aspirate the serum and store at -80 &#176;C for the subsequent analysis of cTnT.</li>
	<li>Use an analyzer to perform the quantitative measurement of the cTnT with a high sensitivity immunoassay based on electrochemiluminescence technology. Take 1 mL of the serum and put it into a special test tube for measuring cTnT. Then insert the tube in the analyzer and press the start button. 
	NOTE: The human cTnT protein itself consists of 288 amino acids. Two monoclonal antibodies are used for the assay which are specifically directed against human cardiac troponin T. The antibodies recognize the central part of cardiac troponin T protein4, specifically targeting two epitopes at amino acid positions 125-131 and 136-147.</li>
</ol>
3. Exercise Protocols
<ol>
	<li>In each exercise session, instruct the 4 groups to follow the steps below.
	<ol>
		<li>Complete an identical 10 min warm-up at 50-60% of HRmax (percentage of individual maximal heart rate during exercise session) and 5 min cool down at 20 W.</li>
		<li>Following the warm-up. Have a 2 min recovery period, where participants remain seated but stationary on the cycle ergometer.</li>
		<li>Direct the participants to accelerate as soon as possible at the beginning of each exercise bout to reach the intended intensity. During this time a researcher sets the respective exercise protocol in a PC computer and then counts down, &#34;5-4-3-2-1-Go!&#34;. At the command of &#34;Go!&#34;, participants start to exercise and activate the computerized system. 
		NOTE: For the MCE, HIE and SIE, accelerate to the planned intensity (see step 2.1.3), i.e. 60%, 90% and 120% V&#775;O2max, respectively. For the RSE, accelerate to &#8220;all-out&#8221; exercise (see step 3.4). The ergometer is linked to a PC computer with specific software.</li>
		<li>Instruct the participants to remain seated while cycling and secure their feet to the pedals using toe clips, and verbally encourage the participants to give a maximal effort to exercise at the desired intensity throughout each session.</li>
	</ol>
	</li>
	<li>HIE protocol: Repeat 4 min bouts of exercise on a stress testing cycle ergometer at an intensity of 90% V&#775;O2max, followed by a 3 min passive recovery (complete rest) until the targeted 200 kJ of work is achieved.</li>
	<li>SIE protocol: Repeat 1 min bouts of exercise on a stress testing cycle ergometer at an intensity of 120% of V&#775;O2max, followed by a 1.5 min passive recovery until the targeted 200 kJ of work is achieved.</li>
	<li>RSE protocol: Repeat 6 s &#8220;all-out&#8221; sprints interspersed with 9 s passive recovery periods on a Wingate testing cycle ergometer, with a resistance of 1.0 kg until the targeted 40 repetitions are achieved, and the total mechanical work was recorded.</li>
	<li>MCE protocol: Perform continuous cycling exercise, until a target of 200 kJ of work is achieved, at an intensity of 60% V&#775;O2max.</li>
</ol>
4. Statistical Analyses
<ol>
	<li>Perform data analysis using a statistical software package. Evaluate the normality of the data using the Kolmogorov&#8211;Smirnov test12. Use P &#60; 0.05 for assessing statistical significance.</li>
	<li>Compare the differences in HRmean (mean heart rate during exercise session) and %HRmax across the four groups (HIE, SIE, RSE and MCE) and the two observed exercise sessions (1ST and 6TH) using two-way ANOVA, with repeated measures. Use the Newman&#8211;Keuls post-hoc test for cases in which the main effect is significant.</li>
	<li>Compare cTnT across the time points (pre-exercise and peak post-exercise) and two observed exercise sessions (1ST and 6TH) using the non-parametric Wilcoxon signed ranks test because of the skewed distribution of the cTnT data. Further, the Kruskal-Wallis test was used to assess the statistical significance of differences in cTnT levels across the four groups (HIE, SIE, RSE and MCE), and the Mann-Whitney U test was used for pairwise comparisons where appropriate.</li>
</ol>

<ol>
	<li>Blair, S. N., Morris, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Healthy+hearts--and+the+universal+benefits+of+being+physically+active:+physical+activity+and+health.">Healthy hearts--and the universal benefits of being physically active: physical activity and health.</a> Annals of Epidemiology. 19 (4), 253-256 (2009).</li><li>Siscovick, D. S., Weiss, N. S., Fletcher, R. H., Lasky, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+incidence+of+primary+cardiac+arrest+during+vigorous+exercise.">The incidence of primary cardiac arrest during vigorous exercise.</a> The New England Journal of Medicine. 311 (14), 874-877 (1984).</li><li>Albert, C. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Triggering+of+sudden+death+from+cardiac+causes+by+vigorous+exertion.">Triggering of sudden death from cardiac causes by vigorous exertion.</a> The New England Journal of Medicine. 343 (19), 1355-1361 (2000).</li><li>Thygesen, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fourth+universal+definition+of+myocardial+infarction+(2018).">Fourth universal definition of myocardial infarction (2018).</a> European Heart Journal. 40 (3), 237-269 (2019).</li><li>Gresslien, T., Agewall, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Troponin+and+exercise.">Troponin and exercise.</a> International Journal of Cardiology. 221, 609-621 (2016).</li><li>MacInnis, M. J., Gibala, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physiological+adaptations+to+interval+training+and+the+role+of+exercise+intensity.">Physiological adaptations to interval training and the role of exercise intensity.</a> The Journal of Physiology. 595 (9), 2915-2930 (2017).</li><li>Poon, E. T., Sheridan, S., Chung, A. P., Wong, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Age+specific+affective+responses+and+self-efficacy+to+acute+high-intensity+interval+training+and+continuous+exercise+in+insufficiently+active+young+and+middle-aged+men.">Age specific affective responses and self-efficacy to acute high-intensity interval training and continuous exercise in insufficiently active young and middle-aged men.</a> Journal of Exercise Science and Fitness. 16 (3), 106-111 (2018).</li><li>Gaesser, G. A., Angadi, S. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-intensity+interval+training+for+health+and+fitness:+can+less+be+more.">High-intensity interval training for health and fitness: can less be more.</a> Journal of Applied Physiology(1985). 111 (6), 1540-1541 (2011).</li><li>Mehta, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Post-exercise+cardiac+troponin+release+is+related+to+exercise+training+history.">Post-exercise cardiac troponin release is related to exercise training history.</a> International Journal of Sports Medicine. 33 (5), 333-337 (2012).</li><li>World Health Organization. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Asia-Pacific+perspective:+redefining+obesity+and+its+treatment.">The Asia-Pacific perspective: redefining obesity and its treatment.</a> World Health Organization. , (2000).</li><li>Medbo, J. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anaerobic+capacity+determined+by+maximal+accumulated+O2+deficit.">Anaerobic capacity determined by maximal accumulated O2 deficit.</a> Journal of Applied Physiology. 64 (1), 50-60 (1985).</li><li>Tian, Y., Nie, J., Huang, C., George, K. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+kinetics+of+highly+sensitive+cardiac+troponin+T+release+after+prolonged+treadmill+exercise+in+adolescent+and+adult+athletes.">The kinetics of highly sensitive cardiac troponin T release after prolonged treadmill exercise in adolescent and adult athletes.</a> Journal of Applied Physiology. 113 (3), 418-425 (2012).</li><li>Nie, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+impact+of+high-intensity+interval+training+on+the+cTnT+response+to+acute+exercise+in+sedentary+obese+young+women.">The impact of high-intensity interval training on the cTnT response to acute exercise in sedentary obese young women.</a> Scandinavian Journal of Medicine &amp; Science in Sports. 29 (2), 160-170 (2019).</li><li>Zhang, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+cTnT+response+to+acute+exercise+at+the+onset+of+an+endurance+training+program:+evidence+of+exercise+preconditioning.">The cTnT response to acute exercise at the onset of an endurance training program: evidence of exercise preconditioning.</a> European Journal of Applied Physiology. 119 (4), 847-855 (2019).</li><li>Nie, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+high-intensity+interval+training+and+moderate-intensity+continuous+training+on+resting+and+postexercise+cardiac+troponin+T+concentration.">Impact of high-intensity interval training and moderate-intensity continuous training on resting and postexercise cardiac troponin T concentration.</a> Experimental Physiology. 103 (3), 370-380 (2018).</li><li>Levinger, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=What+Doesn't+Kill+You+Makes+You+Fitter:+A+Systematic+Review+of+High-Intensity+Interval+Exercise+for+Patients+with+Cardiovascular+and+Metabolic+Diseases.">What Doesn't Kill You Makes You Fitter: A Systematic Review of High-Intensity Interval Exercise for Patients with Cardiovascular and Metabolic Diseases.</a> Clinical Medicine Insights: Cardiology. 9, 53-63 (2015).</li></ol>

The authors declare that they have no competing financial interests.

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 (&#8220;near maximal&#8221; efforts) and SIE (&#8220;supramaximal&#8221; efforts), using a common classification scheme6. In addition, RSE is a particularly intense form of SIE, where the activity is &#8220;all-out&#8221; but only lasts for 3 to 7 s6. To the best of our knowledge, this is the first integrated s...

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 exercise2,3. Individuals with low levels of regular physical activity show higher risk towards AMI2,3. 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 diagnostic role of the cTnT assay5.
The repetitive bouts of relatively intense exercise interspersed with short breaks are a typical element of high-intensity interval exercise (HIE), which is growing in popularity in various fields such as cardiac rehabilitation, health and fitness6,7. The widespread interest in HIE is due in part to the ability of HIE training to elicit beneficial physiological adaptations similar or superior to the traditional moderate-intensity continuous exercise (MCE) training, despite a reduced total exercise volume and time commitment6. However, concerns related to the safety of HIE have been expressed due to the high cardiac demand8. To date, available data related to cTnT release upon HIE is limited. Moreover, no previous integrated study has investigated the effect of various modalities of HIE and traditional MCE on the appearance of cTnT with exercise. Thus, it is unclear whether, with equalization of total mechanical work between HIE and MCE, different exercise formats will lead to the distinction in cTnT concentrations and what the range of the elevated cTnT values is. Given that exercise conducted at higher intensities might lead to a higher risk of cardiac events2,3, it is pertinent to develop a representative HIE and MCE proposals with the known range of cTnT responses. The evaluation of exercise-associated cTnT elevation could potentially be helpful in clinical decision-making and assist clinical physiologists in developing more effective and safe exercise prescriptions.
Consequently, we outline protocols of the three representative types of HIE and one representative type of MCE to gather physiological data while observing cTnT responses. Considering that the risk of acute cardiac events is higher in people who do not engage in regular exercise2,3 and the overall release of cTnT induced by exercise reduces with regular training9, this study recruited sedentary, overweight females who completed a 10 day training program. This provided the prospect to work in the early stage of training and target an under-researched group.

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

impact of high-intensity interval exercise and moderate-intensity continuous exercise on the cardiac troponin t level at an early stage of training

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% V&#775;O2max interspersed with 3 min rest, 200 kJ/session); sprint interval exercise (SIE, repeated 1 min cycling at 120% V&#775;O2max 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% V&#775;O2max, 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.

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 HRmean and %HRmax, at the 1ST assessment is similar (all P &#62; 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 bet...

Watch this Scientific Journal Video about Impact of High-intensity Interval Exercise and Moderate-Intensity Continuous Exercise on the Cardiac Troponin T Level at an Early Stage of Training at JoVE.co

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

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.

An elevation in cardiac troponin T (cTnT), as a highly specific biomarker of cardiomyocyte damage, after moderate-intensity continuous exercise (MCE) has ...

impact-high-intensity-interval-exercise-moderate-intensity-continuous

Research

JoVE Journal

Behavior

7.2K Views.  Hebei Normal University. We presenteren protocol van drie representatieve types van hoge intensiteit interval oefening en een representatief type van matige intensiteit continue oefening. Om de reactie van circulerende cardiale troponine T-concentratie te observeren om uit te oefenen. We rekruteerden sedentaire, overgewicht vrouwen, die een 10-daagse trainingsprogramma voltooid.Dit stelde ons in staat om in een vroeg stadium van de opleiding te werken. En richt je op een onder onderzochte groep. Het frame van ...

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

A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis

Each year, an estimated 785,000 Americans will have a new coronary attack, or acute coronary syndrome (ACS). The pathophysiology of ACS involves rupture of an atherosclerotic plaque; hence, treatment is aimed at plaque stabilization in order to prevent cellular death. However, there is considerable debate among clinicians, about which treatment pathway is best: early invasive using percutaneous coronary intervention (PCI/stent) when indicated or a conservative approach (i.e., medication only with PCI/stent if recurrent symptoms occur).
There are three types of ACS: ST elevation myocardial infarction (STEMI), non-ST elevation MI (NSTEMI), and unstable angina (UA). Among the three types, NSTEMI/UA is nearly four times as common as STEMI. Treatment decisions for NSTEMI/UA are based largely on symptoms and resting or exercise electrocardiograms (ECG). However, because of the dynamic and unpredictable nature of the atherosclerotic plaque, these methods often under detect myocardial ischemia because symptoms are unreliable, and/or continuous ECG monitoring was not utilized.
Continuous 12-lead ECG monitoring, which is both inexpensive and non-invasive, can identify transient episodes of myocardial ischemia, a precursor to MI, even when asymptomatic. However, continuous 12-lead ECG monitoring is not usual hospital practice; rather, only two leads are typically monitored. Information obtained with 12-lead ECG monitoring might provide useful information for deciding the best ACS treatment.
Purpose. Therefore, using 12-lead ECG monitoring, the COMPARE Study (electroCardiographic evaluatiOn of ischeMia comParing invAsive to phaRmacological trEatment) was designed to assess the frequency and clinical consequences of transient myocardial ischemia, in patients with NSTEMI/UA treated with either early invasive PCI/stent or those managed conservatively (medications or PCI/stent following recurrent symptoms). The purpose of this manuscript is to describe the methodology used in the COMPARE Study.
Method. Permission to proceed with this study was obtained from the Institutional Review Board of the hospital and the university. Research nurses identify hospitalized patients from the emergency department and telemetry unit with suspected ACS. Once consented, a 12-lead ECG Holter monitor is applied, and remains in place during the patient's entire hospital stay. Patients are also maintained on the routine bedside ECG monitoring system per hospital protocol. Off-line ECG analysis is done using sophisticated software and careful human oversight.

Continuous 12-lead electrocardiographic (ECG) monitoring can identify transient myocardial ischemia, even when asymptomatic, among patients with suspected acute coronary syndrome (ACS). In this article we describe our method for initiating patient monitoring using a Holter device, downloading the ECG data for off-line analysis, and how to utilize the ECG software to identify transient ischemia.

Each year, an estimated 785,000 Americans will have a new coronary attack, or acute coronary syndrome (ACS). The pathophysiology of ACS involves rupture ...

Medicine

Short Session High Intensity Interval Training and Treadmill Assessment in Aged Mice

High intensity interval training (HIIT) is emerging as a therapeutic approach to prevent, delay, or ameliorate frailty. In particular short session HIIT, with regimens less than or equal to 10 min is of particular interest as several human studies feature routines as short as a few minutes a couple times a week. However, there is a paucity of animal studies that model the impacts of short session HIIT. Here, we describe a methodology for an individually tailored and progressive short session HIIT regimen of 10 min given 3 days a week for aged mice using an inclined treadmill. Our methodology also includes protocols for treadmill assessment. Mice are initially acclimatized to the treadmill and then given baseline flat and uphill treadmill assessments. Exercise sessions begin with a 3 min warm-up, then three intervals of 1 min at a fast pace, followed by 1 min at an active recovery pace. Following these intervals, the mice are given a final segment that starts at the fast pace and accelerates for 1 min. The HIIT protocol is individually tailored as the speed and intensity for each mouse are determined based upon initial anaerobic assessment scores. Additionally, we detail the conditions for increasing or decreasing the intensity for individual mice depending on performance. Finally, intensity is increased for all mice every two weeks. We previously reported in this protocol enhanced physical performance in aged male mice and here show it also increases treadmill performance in aged female mice. Advantages of our protocol include low administration time (about 15 min per 6 mice, 3 days a week), strategy for individualizing for mice to better model prescribed exercise, and a modular design that allows for the addition or removal of the number and length of intervals to titrate exercise benefits.

Short session (&#8804;10 min) high intensity interval training (HIIT) is emerging as an alternative to longer exercise modalities, yet the shorter variants are rarely modeled in animal studies. Here, we describe a 10 min, 3 day a week, uphill treadmill HIIT protocol that enhances physical performance in male and female aged mice.

High intensity interval training (HIIT) is emerging as a therapeutic approach to prevent, delay, or ameliorate frailty. In particular short session HIIT, ...

A Rapidly Incremented Tethered-Swimming Maximal Protocol for Cardiorespiratory Assessment of Swimmers

Incremental exercise testing is the standard means of assessing cardiorespiratory capacity of endurance athletes. While the maximal rate of oxygen consumption is typically used as the criterion measurement in this regard, two metabolic breakpoints that reflect changes in the dynamics of lactate production/consumption as the work rate is increased are perhaps more relevant for endurance athletes from a functional standpoint. Exercise economy, which represents the rate of oxygen consumption relative to performance of submaximal work, is also an important parameter to measure for endurance-athlete assessment. Ramp incremental tests comprising a gradual but rapid increase in work rate until the limit of exercise tolerance is reached are useful for determining these parameters. This type of test is typically performed on a cycle ergometer or treadmill because there is a need for precision with respect to work-rate incrementation. However, athletes should be tested while performing the mode of exercise required for their sport. Consequently, swimmers are typically assessed during free-swimming incremental tests where such precision is difficult to achieve. We have recently suggested that stationary swimming against a load that is progressively increased (incremental tethered swimming) can serve as a &#34;swim ergometer&#34; by allowing sufficient precision to accommodate a gradual but rapid loading pattern that reveals the aforementioned metabolic breakpoints and exercise economy. However, the degree to which the peak rate of oxygen consumption achieved during such a protocol approximates the maximal rate that is measured during free swimming remains to be determined. In the present article, we explain how this rapidly incremented tethered-swimming protocol can be employed to assess the cardiorespiratory capacity of a swimmer. Specifically, we explain how assessment of a short-distance competitive swimmer using this protocol revealed that his rate of oxygen uptake was 30.3 and 34.8 mL&#8729;min-1&#8729;kg-1BM at his gas-exchange threshold and respiratory compensation point, respectively.

As opposed to measurement during free swimming, which presents inherent challenges and limitations, determination of important parameters of cardiorespiratory function for swimmers can be made using a more feasible and easier to administer tethered-swimming rapidly incremented protocol with gas exchange and ventilatory data collection.

Incremental exercise testing is the standard means of assessing cardiorespiratory capacity of endurance athletes. While the maximal rate of oxygen ...

Biochemistry

Evaluation of Blood Lactate and Plasma Insulin During High-intensity Exercise by Antecubital Vein Catheterization

The measurement of metabolic and endocrinal markers during physical activity is of relevance to understanding the physiological implications of different exercise modalities. During some exercise modalities (e.g., high-intensity interval exercise), blood metabolites and hormonal levels change in short periods of time. In the present study, we describe a method to catheterize the antecubital vein, which allows the collection of several blood samples during exercise. Insulin and venous lactate concentrations were measured during high-intensity exercise by the application of the described method. The exercise consisted of three 30 s bouts of high-intensity exercise separated by 4 min of recovery. After the last recovery period, a Wingate test was performed. Blood samples from the antecubital vein were obtained before and after each 30 s bout and before and after the Wingate test. As a result, it was possible to evaluate the plasma insulin and venous blood lactate variations during the exercise.

Here we present a protocol to obtain several blood samples from the antecubital vein during high-intensity interval training. This protocol may be useful for the measurement of blood metabolites and endocrinal markers during exercise.

The measurement of metabolic and endocrinal markers during physical activity is of relevance to understanding the physiological implications of different ...

Immunology and Infection

Accumulated High-intensity Interval Training Protocol: A New Approach to Study Health Markers in Wistar Rats

High-Intensity Interval Training (HIIT) and accumulated exercises are two time-efficient programs to improve health in humans and animal models. However, to date, there are no studies on whether HIIT performed in an accumulated fashion is as effective as a traditional HIIT performed with single daily sessions in improving health markers. This paper presents the effects of a new HIIT protocol, called accumulated HIIT, on body weight gain, maximal oxygen consumption (VO2max), and cardiac hypertrophy in young Wistar rats. 
Sixty-day-old male Wistar rats were assigned to three groups: untrained (UN; n = 16), HIIT performed with single daily sessions (1-HIIT; n = 16), and HIIT performed with three daily sessions (3-HIIT; n = 16). Body weight and VO2max were recorded before and after the training period. The VO2max measurements were taken using a metabolic analyzer at the maximal running velocity (Vmax). The training was performed for both HIIT groups five days per week over eight weeks with the same weekly progression of the exercise intensity (85-100% Vmax). The 1-HIIT group performed single daily sessions (6 bouts of 1 min interspersed with 1 min of passive recovery). The 3-HIIT group performed three daily sessions (2 bouts of 1 min interspersed with 1 min of passive recovery with an interval of 4 h between bouts). After the last VO2max test, the rats were euthanized, and their hearts were harvested and weighed.
The results showed that 3-HIIT had similar beneficial effects to 1-HIIT in preventing body weight gain, improving VO2max, and inducing cardiac hypertrophy. These findings reveal for the first time the efficacy of an accumulated HIIT protocol on the health markers of young Wistar rats. This new HIIT protocol may be more feasible than traditional HIIT protocols as exercise can be split into very short sessions throughout a day in this new approach.

Here, we present accumulated high-intensity interval training (HIIT) protocols, which may be a more feasible and time-efficient strategy than traditional HIIT protocols.

High-Intensity Interval Training (HIIT) and accumulated exercises are two time-efficient programs to improve health in humans and animal models. However, ...

A Real-World High-Intensity Interval Training Protocol for Cardiorespiratory Fitness Improvement

High-Intensity Interval Training (HIIT) has emerged as an interesting time-efficient approach to increase exercise adherence and improve health. However, few studies have tested the efficiency of HIIT protocols in a &#34;real world&#34; setting, e.g., HIIT protocols designed for outdoor spaces without specialized equipment. This study presents a &#34;real world&#34; training protocol, named &#34;beep training&#34;, and compares the efficiency of a HIIT regiment versus a traditional long-duration Moderate-Intensity Continuous Training (MICT) regiment using this beep training protocol on VO2 max of overweight untrained men. Twenty-two subjects performed outdoor running with MICT (n = 11) or HIIT (n = 11). Cardiorespiratory fitness was assessed before and after training protocols using a metabolic analyzer. Both training protocols were performed 3 days a week for 8 weeks using the Beep Test results. The MICT group performed the exercise program at 60%-75% of the maximum speed of the 20 m shuttle test (Vmax) and with a progression of the distance of 3,500-5,000 m. The HIIT group performed the interval exercise with 7-10 bouts of 200 m at 85%-100% of the maximum speed of the 20 m shuttle test (Vmax), interspersed with 1 min of passive recovery. Although the HIIT group presented a significantly lower training volume than the MICT group (p &#60; 0.05) after 8 weeks of beep training, HIIT was superior to MICT in improving VO2 max (MICT: ~4.1%; HIIT: ~7.3%; p &#60; 0.05). The &#34;real world&#34; HIIT regiment based on beep training protocol is a time-efficient, low-cost, and easy-to-implement protocol for overweight untrained men.

This study presents a low-cost and easy-to-implement "real world" high-intensity interval training (HIIT) protocol for scientific research and discusses its efficiency for cardiorespiratory fitness.

High-Intensity Interval Training (HIIT) has emerged as an interesting time-efficient approach to increase exercise adherence and improve health. However, ...

Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice

Regular physical exercise is a major contributor to cardiovascular health, influencing various metabolic as well as electrophysiological processes. However, in certain cardiac diseases such as inherited arrhythmia syndromes, e.g., arrhythmogenic cardiomyopathy (ACM) or myocarditis, physical exercise may have negative effects on the heart leading to a proarrhythmogenic substrate production. Currently, the underlying molecular mechanisms of exercise-related proarrhythmogenic remodeling are largely unknown, thus it remains unclear which frequency, duration, and intensity of exercise can be considered safe in the context of disease(s).
The proposed method allows to study proarrhythmic/antiarrhythmic effects of physical exercise by combining treadmill training with real-time monitoring of the ECG. Implantable telemetry devices are used to continuously record the ECG of freely moving mice over a period of up to 3 months both at rest and during treadmill training. Data acquisition software with its analysis modules is used to analyze basic ECG parameters such as heart rate, P wave duration, PR interval, QRS interval, or QT duration at rest, during and after training. Furthermore, heart rate variability (HRV) parameters and occurrence of arrhythmias are evaluated. In brief, this manuscript describes a step-by-step approach to experimentally explore exercise induced effects on cardiac electrophysiology, including potential proarrhythmogenic remodeling in mouse models.

Electrocardiogram (ECG) is the key variable to understanding cardiac electrophysiology. Physical exercise has beneficial effects but may also be harmful in the context of cardiovascular diseases. This manuscript provides a method of recording real-time ECG during exercise, which can serve to investigate its effects on cardiac electrophysiology in mice.

Regular physical exercise is a major contributor to cardiovascular health, influencing various metabolic as well as electrophysiological processes. ...

A Chronic High-Intensity Interval Training and Diet-Induced Obesity Model to Maximize Exercise Effort and Induce Physiologic Changes in Rats

Compared to continuous-moderate or low-intensity training, high-intensity interval training (HIIT) is a more time-efficient alternative method that results in similar physiologic benefits. This paper presents a HIIT protocol that can be used to assess various health markers in a Sprague-Dawley rat model of diet-induced obesity. Female Sprague Dawley rats aged 21 days old were randomly assigned to the following groups: control (CON, n = 10), exercise-trained (TRN, n = 10), high-fat diet (HFD, n = 10), and high-fat diet/exercise training (HFD/TRN, n = 10). The control diets consisted of commercial laboratory chow with 10% kilocalories (kcal) from fat (3.82 kcal/g), and the high-fat diets (HFD) consisted of 45% kcal from fat (4.7 kcal/g). The animals had ad libitum access to their assigned diet throughout the study. After an 8 week diet induction period, the exercise cohorts completed four HIIT sessions per week for 8 weeks. Each HIIT session consisted of 10 intervals of 1 min sprints/2 min rest using a rodent treadmill with a motor-driven belt. After the 8 weeks of training, the animals were sacrificed for tissue collection. The results revealed no differences in the distance run between the TRN and HFD/TRN groups, and the training speed steadily increased over the duration of the study, with a final running speed of 115 cm/s and 111 cm/s for the TRN and HFD/TRN groups, respectively. The weekly caloric intake was decreased (p &#60; 0.05) in the TRN group relative to the CON group but increased (p &#60; 0.05) in the HFD/TRN group relative to the HFD group. Lastly, the animals on the HFD had greater (p &#60; 0.05) adiposity, and the trained animals had reduced (p &#60; 0.05) adiposity relative to controls. This protocol demonstrates an efficient method to evaluate the effects of HIIT on various physiologic outcomes in a diet-induced obesity model.

This paper presents the morphometric responses and training performance outcomes of a high-intensity interval training (HIIT) protocol in a Sprague-Dawley rat model of diet-induced obesity. The purpose of this protocol was to maximize exercise intensity and determine the physiologic responses to HIIT in lean and obese rats.

Compared to continuous-moderate or low-intensity training, high-intensity interval training (HIIT) is a more time-efficient alternative method that ...

Biology

A Swimming-Induced Zebrafish Exercise Apparatus for Versatile Training Approaches

To comprehensively investigate the effects of exercise on health and disease, animal models play a pivotal role. Zebrafish, a widely utilized vertebrate model organism, offers a unique platform for such studies. This study introduced the development of a cost-effective apparatus tailored for zebrafish exercise studies utilizing readily available materials. The device is founded on the principles of a swim tunnel and encompasses a network of pipes and valves linked to a submersible pump. Water flow is meticulously monitored by a sensor and regulated via valves. To assess the apparatus&#39;s effectiveness, two training protocols were implemented: moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT). Fish were trained collectively, and their swimming performance was assessed through an endurance test. Both training protocols led to improvements in swimming performance following 30 days of training and induced alterations in the molecular response to exercise compared to a sedentary control group. Notably, HIIT demonstrated superior efficiency over MICT. The zebrafish training system proved to be a valuable tool for investigations in exercise physiology and further advances the utility of the zebrafish model in this field.

The exercise apparatus designed for less fortunate fish facilitates the implementation of diverse exercise protocols with varying intensities by manipulating water flow speed, achievable through rheotaxis.

To comprehensively investigate the effects of exercise on health and disease, animal models play a pivotal role. Zebrafish, a widely utilized vertebrate ...

Blood Studies for Cardiovascular System I: Cardiac Biomarkers

Cardiac biomarkers are enzymes, proteins, and hormones released into the blood when cardiac cells are injured. They are powerful tools for triaging.
The essential diagnostic tools for detecting myocardial necrosis and monitoring individuals suspected of having acute coronary syndrome (ACS) include:
Troponins
Troponins, particularly cardiac troponins I and T, are the most precise and sensitive markers of myocardial injury. They are detectable within 4-6 hours of myocardial injury and remain elevated for 10-14 days. High-sensitivity troponin assays have revolutionized the timely detection of ACS, allowing for earlier intervention and improved patient outcomes. Elevated troponin levels are definitive indicators of myocardial infarction, guiding immediate therapeutic interventions and informing prognosis.
Myoglobin
Myoglobin, an oxygen-binding protein, is released early after myocardial injury, often within 1 to 3 hours. It reaches peak concentrations at 12 hours and returns to baseline quickly. The early release of myoglobin makes it a crucial marker for rapidly identifying myocardial injury, although its specificity is lower than that of other biomarkers.
Creatine Kinase-MB (CK-MB)
Creatine kinase-MB (CK-MB), a subtype of creatine kinase, is released during myocardial infarction (MI). CK-MB levels rise rapidly, peaking within 12 to 24 hours post-infarction and normalizing within 48 hours. The quick rise and fall of CK-MB levels make them particularly useful in detecting reinfarction, offering a temporal marker for recurring myocardial injury.
Clinical Significance of Cardiac Biomarkers
Myocardial cells that become necrotic from prolonged ischemia or trauma release specific enzymes (creatine kinase [CK]), CK isoenzymes (CK-MB), and proteins (myoglobin, troponin T, and troponin I). These substances leak into the interstitial spaces of the myocardium and are carried by the lymphatic system into general circulation. As a result, abnormally high levels of these substances can be detected in serum blood samples, aiding in diagnosing and managing myocardial injury and ACS.

Cardiac biomarkers are enzymes, proteins, and hormones released into the blood during cardiac cell injury. They aid in the management of myocardial ...

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

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