The effect of whole-body high-intensity interval training on heart rate variability in insufficiently active adults

Effects of Exercise Training on Heart Rate Variability in Healthy Adults: A Systematic Review and Meta-analysis of Randomized Controlled Trials

This meta-analysis was conducted to investigate the effects of exercise training on heart rate variability (HRV) parameters associated with the autonomic nervous system (ANS) activity. Randomized controlled trials (RCTs) involving healthy adults (aged ≥ 18 years) were included. We searched PubMed, Scopus, Web of Science, and EBSCO databases to identify relevant studies. A random-effects meta-analysis was performed using the standardized mean difference (SMD) and 95% confidence interval (CI). Sixteen RCTs with a total of 623 participants were selected for the final analysis. The analysis showed that exercise training improved the standard deviation of normal-to-normal intervals (SDNN) (SMD: 0.58 (0.16, 1.00); p = 0.007), the root mean square of successive differences in heart period series (RMSSD) (SMD: 0.84 (0.36, 1.31); p = 0.0005), and the absolute power of high-frequency band (HF) (SMD: 0.89 (0.27, 1.51); p = 0.005) parameters compared to the control group. Analysis of the moderator variables showed that the effect of exercise on HRV indices may be influenced by sex, age, and type of exercise used, specifically in HF band, absolute power of low-frequency band (LF), and LF/HF ratio parameters. Despite the limited number of existing RCTs related to the subject, the results suggest that exercise training enhances HRV parameters associated with vagal-related activity (RMSSD and HF) and both sympathetic and parasympathetic activities (SDNN). This study overcomes the lack of meta-analyses on the effects of exercise training on autonomic modulation among healthy adults and may bridge the gap in understanding the potential physiological underpinnings of the acknowledged positive health benefits of exercise.

Extremely Low-Volume Burpee Interval Training Equivalent to 8 Minutes Per Session Improves Vertical Jump Compared with Sprint Interval Training in Real-World Circumstances

ABSTRACT

Pérez-Ifrán, P, Magallanes, CA, de S. Castro, FA, Astorino, TA, and Benítez-Flores, S. Extremely low-volume burpee interval training equivalent to 8 minutes per session improves vertical jump compared with sprint interval training in real-world circumstances. J Strength Cond Res 38(1): 10-20, 2024-The aim of this study was to compare the cardiometabolic and physical effects of 2 time-matched high-intensity programs in a real-world environment. Forty-three active and healthy adults (sex = 31 men and 12 women; age = 27 ± 5 years; peak heart rate [HR peak ] = 190.7 ± 10.6 beat·min -1 ) were randomized to 2 very low-volume protocols (∼8 minutes): sprint interval training (SIT) ( n = 15), burpee interval training (BIT) ( n = 15), and control (CON) ( n = 13). Subjects in SIT and BIT performed 5 days of 10 × 4 second "all-out" efforts with 30 seconds of recovery. Body composition, blood pressure, countermovement jump (CMJ), 10-m sprint, shuttle run test (SRT), autonomic modulation , self-efficacy, and intention were evaluated before and after training. Sprint interval training elicited a higher %HR peak , energy expenditure, rating of perceived exertion category ratio 10 scale, and feeling scale than BIT ( p < 0.05). SRT distance was significantly improved in SIT ( p = 0.03, d = 0.62), whereas CMJ height was significantly enhanced in BIT ( p = 0.0014, d = 0.72). Self-efficacy progressively worsened for SIT than for BIT as sessions increased, and significant differences were found in 5× a week frequency between protocols ( p = 0.040, d = 0.79). No differences in intention to engage were detected between the regimens ( p > 0.05). No changes were observed in body composition, blood pressure, 10-m sprint, SRTV̇O 2max , or autonomic variables with training ( p > 0.05). Results exhibit that extremely low-volume SIT improved running performance, whereas BIT increased the vertical jump.

Effect of Exercise Modality on Heart Rate Variability in Adults: A Systematic Review and Network Meta-Analysis

Background

The purpose of this study was to use a network meta-analysis (NMA) to compare the effects of aerobic training (AT), resistance training (RT), combined training (CBT), and high-intensity interval training (HIIT) on adult heart rate variability (HRV).

Methods

We searched PubMed, the Cochrane Library, Embase, the Web of Science, Wanfang Data, and the China National Knowledge Infrastructure to identify randomized controlled trials on the effects of exercise on HRV in adults. The search was conducted from the outset of these databases to April 2023. Two reviewers independently screened the retrieved articles, extracted raw data from the relevant studies, and assessed the possible risk of bias in the included studies.

Results

The NMA showed that HIIT had the greatest effect on the low-frequency (LF) power/high-frequency (HF) power ratio, standard deviation of normal-normal intervals (SDNN), and root mean square of successive differences between adjacent normal-to-normal intervals (RMSSD) (surface under the cumulative ranking curve (SUCRA) = 99.75%, 98.7%, and 84.9%); CBT had the greatest effect on the LF power (SUCRA = 66.3%); RT had the greatest effect on the HF power (SUCRA = 72.5%).

Conclusions

Our NMA and SUCRA ranking results suggest that in adults, HIIT is the most effective exercise modality in improving the SDNN, RMSSD, and LF/HF power ratio; RT for the HF power; CBT for the LF power. Any NMA conducted in the future must fully explore the effects of different exercise modalities on HRV in adult subgroups of different ages and genders.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=424054, identifier: CRD42023424054.

Sex Differences in Heart Rate Variability and Vascular Function Following High-Intensity Interval Training in Young Adults

High-intensityintervaltraining (HIIT) issuperiortoothertrainingstrategies in both male andfemalehealthyindividuals. Understanding sex-specificdifferences in cardiac auto-regulation maycontributetothe optimal trainingstrategiesfor HIIT. The presentstudyaimedtoidentifysexdifferences in heart rate variability (HRV) andvascularfunctionfollowing HIIT in youngadults. Twenty-fourphysicallyactiveyoung male andfemaleadults (M: 12, F: 12, age: 19.5 yr, BMI: 22.1 kg·m-2) volunteeredtoparticipate in thestudy. Participantsperformed 10 boutsof HIIT including 20 s of high-intensitycycling at 115-130% Wmaxfollowedby 100 s ofrecovery. The cardiac auto-regulationsincluding HRV andvascularfunctionweremeasured at five different time points. The R-R interval, rMSSD, and SDNN wererecoveredfaster in malesthan in females after 15 min of HIIT. Thereweresexdifferences in theautonomicnervoussystemwhereln LF andln HF activitiesalongwithsympathovagalbalance (ln LF/HF) weregreater in femalescomparedwithmalesimmediatelyand 15 min after HIIT. However, nosignificantdifferences in bloodpressureand brachial-ankle pulse wavevelocitywereobservedbetween male andfemaleparticipants. Overall, HRV was moreactivated in femalesthan in malesfollowing HIIT, but theacuteresponse in vascularfunction was not different betweensexes. In futurestudies, sex-specificadaptationsofcardiacautoregulationfollowingrepeated HIIT mayneedtobeperformed.

Association of lifestyle habits and cardiovascular risk among sedentary adults

This study aimed to analyze the association of lifestyle habits (physical activity, sleep habits, and eating habits) with cardiovascular risk (arterial stiffness and autonomic nervous system function) among sedentary adults. Sixty adults of sedentariness and physical activity were evaluated by accelerometers; sleep and eating habits were assessed by questionnaires; cardiovascular risks were assessed by pulse wave velocity (PWV), ankle-brachial index, flow mediated dilation, and heart rate variability; circulating biomarkers were also determined. Prolonged sitting (represented by longer maximum length of sedentary bouts, lower length of sedentary breaks, and more total time of sitting) were (P < .05) significantly associated with matrix metalloproteinases, neuropeptide Y, C-reactive protein, peptide Y, ghrelin, and leptin; significant associations (P < .05) were also observed of total time in physical activity with most circulating biomarkers except interleukin-6, tumor necrosis factor-α, and adiponectin. Sleep habits, especially sleep efficiency, were (P < .05) significantly associated with PWV, ankle-brachial index, and circulating biomarkers. Eating habits (including emotional overeating and enjoyment of food) were (P < .05) significantly associated with PWVs and flow mediated dilation; satiety responsiveness and enjoyment of food were (P < .05) significantly associated with low-frequency spectral component expressed in normalized units, high frequency spectral component expressed in normalized units, and ratio between low-frequency/high frequency spectral component expressed in normalized units. The findings indicated that several lifestyle habits among sedentary adults were closely associated with increased cardiovascular risk. Sedentary people were encouraged to live with sufficient physical activity, good sleep, and healthy eating habits for decreasing arterial stiffness and balancing autonomic nervous function.

Remote, Whole-Body Interval Training Improves Muscular Endurance and Cardiac Autonomic Control in Young Adults

High-intensity interval training (HIIT) is an exercise modality acknowledged to maintain physical fitness with more engagement in an active lifestyle compared with other traditional exercise models. Nevertheless, its effects on cardiac control and physical performance in an online-guided setting are not yet clarified. The present work assessed physical fitness and heart rate variability (HRV) before and after an online, home-based HIIT program in college-age students while pandemic lockdowns were in effect. Twenty university students (age: 21.9 ± 2.4 years.) that were solely enrolled in online classes were distributed into three groups: control-CON-(n = 6), 14 min of HIIT-HIIT-14-(n = 8), and 21 min of HIIT-HIIT-21-(n = 6). A maximal push-up test was employed to assess muscular endurance and performance, and resting HRV signals were collected with wireless heart rate monitors and were processed in Kubios HRV Std. (Kubios Oy, Finland). There was an increase in total push-up capacity compared to CON (p < 0.05 HIIT-21 vs. CON; p < 0.001 HIIT-14 vs. CON) after 8 weeks. A significant interaction was observed in high-frequency and low-frequency spectra ratios after the HIIT-21 intervention (p < 0.05). The current work demonstrated that either short- or mid-volume online, whole-body HIIT improves muscle strength, whereas mid-volume HIIT (HIIT-21) was the only intervention that developed a sympathovagal adaptation. This study showed promising results on muscular endurance and cardiac autonomic modulation through whole-body HIIT practice at home.

Does Exercise Training Improve Cardiac-Parasympathetic Nervous System Activity in Sedentary People? A Systematic Review with Meta-Analysis

The aim of this study was to investigate the training-induced effect on cardiac parasympathetic nervous system (PNS) activity, assessed by resting heart rate variability (HRV) and post-exercise heart rate recovery (HRR), in sedentary healthy people. Electronic searches were carried out in PubMed, Embase, and Web of Science. Random-effects models of between-group standardised mean difference (SMD) were estimated. Heterogeneity analyses were performed by means of the chi-square test and I2 index. Subgroup analyses and meta-regressions were performed to investigate the influence of potential moderator variables on the training-induced effect. The results showed a small increase in RMSSD (SMD+ = 0.57 [95% confidence interval (CI) = 0.23, 0.91]) and high frequency (HF) (SMD+ = 0.21 [95% CI = 0.01, 0.42]) in favour of the intervention group. Heterogeneity tests reached statistical significance for RMSSD and HF (p ≤ 0.001), and the inconsistency was moderate (I2 = 68% and 60%, respectively). We found higher training-induced effects on HF in studies that performed a shorter intervention or lower number of exercise sessions (p ≤ 0.001). Data were insufficient to investigate the effect of exercise training on HRR. Exercise training increases cardiac PNS modulation in sedentary people, while its effect on PNS tone requires future study.