Longer Work/Rest Intervals During High-Intensity Interval Training (HIIT) Lead to Elevated Levels of miR-222 and miR-29c

Abstract

Aim: MicroRNA-222 (miR-222) and miR-29c have been identified as important modulators of cardiac growth and may protect against pathological cardiac remodeling. miR-222 and -29c may thus serve as functional biomarkers for exercise-induced cardiac adaptations. This investigation compared the effect of two workload-matched high-intensity interval training (HIIT) protocols with different recovery periods on miR-222 and -29c levels.Methods: Sixty-three moderately trained females and males (22.0 ± 1.7 years) fulfilled the eligibility criteria and were randomized into two HIIT groups using sex and exercise capacity. During a controlled 4-week intervention (two sessions/week) a 4 × 30 HIIT group performed 4 × 30 s runs (all-out, 30 s active recovery) and a 8 × 15 HIIT group performed 8 × 15 s runs (all-out, 15 s active recovery). miR-222 and -29c as well as transforming growth factor-beta1 (TGF-beta1) mRNA levels were determined during high-intensity running as well as aerobic exercise using capillary blood from earlobes. Performance parameters were assessed using an incremental continuous running test (ICRT) protocol with blood lactate diagnostic and heart rate (HR) monitoring to determine HR recovery and power output at individual anaerobic threshold (IAT).Results: At baseline, acute exercise miR-222 and -29c levels were increased only in the 4 × 30 HIIT group (both p < 0.01, pre- vs. post-exercise). After the intervention, acute exercise miR-222 levels were still increased in the 4 × 30 HIIT group (p < 0.01, pre- vs. post-exercise) while in the 8 × 15 HIIT group again no acute effect was observed. However, both HIIT interventions resulted in elevated resting miR-222 and -29c levels (all p < 0.001, pre- vs. post-intervention). Neither of the two miRNAs were elevated at any ICRT speed level at baseline nor follow-up. While HR recovery was improved by >24% in both HIIT groups (both p ≤ 0.0002) speed at IAT was improved by 3.6% only in the 4 × 30 HIIT group (p < 0.0132). Correlation analysis suggested an association between both miRNAs and TGF-beta1 mRNA (all p ≤ 0.006, r ≥ 0.74) as well as change in speed at IAT and change in miR-222 levels (p = 0.024, r = 0.46).Conclusions: HIIT can induce increased circulating levels of cardiac growth-associated miR-222 and -29c. miR-222 and miR-29c could be useful markers to monitor HIIT response in general and to identify optimal work/rest combinations.

Research Article Expression of miR-15b, miR-29b, miR-219 and miR-222 microRNAs in rats with focal cerebral ischemia submitted to physical exercise

“…Although we did not observe a statistically significant difference in our study, miR-222 presented increased levels of expression in animals submitted to cerebral ischemia associated with physical exercise. Therefore, our results corroborated both with Schmitz et al (2018) and with Liu et al (2015). Both studies demonstrated the protective role of physical exercise with increased expression of miR-222 in the cardiovascular system that leads us to suggest a possible systemic vascular action of this miRNA also targeting cerebrovascular regeneration.…”

“…Researchers point out the miRNAs as potential biomarkers for the different intensities of physical exercise training directly involved in various physiological processes and with different response depending on the intensity applied during the training (Schmitz et al, 2018).…”

“…We did not observe differences in miR-29b expression levels in the rats, allowing us to suggest that the experimental design conditions, such as the duration of the ischemia period as well as the reperfusion time are directly associated with the standard expression of miR-29b. Schmitz et al (2018) found increased expression levels of miRNAs miR-222 and miR-29c induced by high-intensity interval training (HIIT) in adult individuals in both men and women. These authors associated both miRNAs as potential cardiac biomarkers in response to HIIT with significant differences evidenced in the study between rest and physical exercise.…”

The Development of a Personalised Training Framework: Implementation of Emerging Technologies for Performance

“…In time, as research in this field progresses, it may be possible to match specific miRNAs to a specific molecular process; here, coaches will be able to understand whether the desired training effects-such as an increase in mitochondrial biogenesis-are actually occurring. We are close to the starting line here; the identification of miR-222 and -29c as drivers of cardiac adaptations following exercise illuminates the potential utility of monitoring the concentrations of these miRNAs-should an individual not see an elevation in these miRNAs, then training intensity/duration may have to be modified to elicit such a change [96]. Additionally, lower concentrations of miR-33 are associated with greater activation of AMPK following aerobic training [102], and miR-29b alters PGC-1α production [103]-both molecular signals for mitochondrial biogenesis-again demonstrating how real-time monitoring of miRNA concentrations could allow coaches to understand the specific adaptations an exercise is stimulating.…”

Commentary: MicroRNA-221/222 Family Counteracts Myocardial Fibrosis in Pressure Overload-Induced Heart Failure

“…Taken together, it seems likely that miRNA-222 may indeed have cardioprotective effects in adult animals (and potentially humans) and in certain disease conditions such as heart failure rather than being detrimental. Several studies have shown that miRNA-222 may be specifically induced by physical exercise not only in athletes ( 10 – 12 ) but also in moderately trained healthy individuals ( 13 ) as well as patients with heart failure ( 8 ). It may therefore be of interest to initiate further studies to investigate to what extend miRNA-222 might be a useful marker to monitor cardioprotective exercise in primary and secondary prevention and rehabilitation of heart failure patients.…”