Dose-response relationship between very vigorous physical activity and cardiovascular health assessed by heart rate variability in adults: Cross-sectional results from the EPIMOV study

Stress influence on real-world driving identified by monitoring heart rate variability and morphologic variability of electrocardiogram signals: the case of intercity roads

Objectives. This study examines which of the heart rate variability (HRV) and morphologic variability (MV) metrics may have the highest accuracy in different stress detection during real-world driving. Methods. The cross-sectional study was carried out among 93 intercity mini-bus male drivers aged 22-67 years. The Trillium 5000 Holter Recorder and GARMIN Virb Elite camera were used to determine heart rate and vehicle speed measurements along the path, respectively. We considered the HRV and MV metrics of electrocardiogram (ECG) signals including the mean RR interval (mRR), mean heart rate (mHR), normalized low-frequency spectrum (nLF), normalized high-frequency spectrum (nHF), normalized very low-frequency spectrum (nVLF), difference of normalized low-frequency spectrum and normalized high-frequency spectrum (dLFHF), and sympathovagal balance index (SVI). Results. The analysis showed that the HRV metrics mHR, mRR, nVLF, nLF, nHF, dLFHF and SVI are effective in mental stress detection while driving as compared to rest time. We obtained a high accuracy of stress detection for MV metrics as compared to the traditional HRV analysis, of approximately 92%. Conclusions. Our findings indicate that driver stress could be detected with an accuracy of 92% using MV metrics as an accurate physiological index of the driver's state.

Accelerometer-Measured Physical Activity Data Sets (Global Physical Activity Data Set Catalogue) That Include Markers of Cardiometabolic Health: Systematic Scoping Review

BACKGROUND

Cardiovascular disease accounts for 17.9 million deaths globally each year. Many research study data sets have been collected to answer questions regarding the relationship between cardiometabolic health and accelerometer-measured physical activity. This scoping review aimed to map the available data sets that have collected accelerometer-measured physical activity and cardiometabolic health markers. These data were then used to inform the development of a publicly available resource, the Global Physical Activity Data set (GPAD) catalogue.

OBJECTIVE

This review aimed to systematically identify data sets that have measured physical activity using accelerometers and cardiometabolic health markers using either an observational or interventional study design.

METHODS

Databases, trial registries, and gray literature (inception until February 2021; updated search from February 2021 to September 2022) were systematically searched to identify studies that analyzed data sets of physical activity and cardiometabolic health outcomes. To be eligible for inclusion, data sets must have measured physical activity using an accelerometric device in adults aged ≥18 years; a sample size >400 participants (unless recruited participants in a low- and middle-income country where a sample size threshold was reduced to 100); used an observational, longitudinal, or trial-based study design; and collected at least 1 cardiometabolic health marker (unless only body mass was measured). Two reviewers screened the search results to identify eligible studies, and from these, the unique names of each data set were recorded, and characteristics about each data set were extracted from several sources.

RESULTS

A total of 17,391 study reports were identified, and after screening, 319 were eligible, with 122 unique data sets in these study reports meeting the review inclusion criteria. Data sets were found in 49 countries across 5 continents, with the most developed in Europe (n=53) and the least in Africa and Oceania (n=4 and n=3, respectively). The most common accelerometric brand and device wear location was Actigraph and the waist, respectively. Height and body mass were the most frequently measured cardiometabolic health markers in the data sets (119/122, 97.5% data sets), followed by blood pressure (82/122, 67.2% data sets). The number of participants in the included data sets ranged from 103,712 to 120. Once the review processes had been completed, the GPAD catalogue was developed to house all the identified data sets.

CONCLUSIONS

This review identified and mapped the contents of data sets from around the world that have collected potentially harmonizable accelerometer-measured physical activity and cardiometabolic health markers. The GPAD catalogue is a web-based open-source resource developed from the results of this review, which aims to facilitate the harmonization of data sets to produce evidence that will reduce the burden of disease from physical inactivity.

Self-recorded heart rate variability profiles are associated with health and lifestyle markers in young adults

PURPOSE

To quantify associations between self-recorded heart rate variability (HRV) profiles and various health and lifestyle markers in young adults.

METHODS

Otherwise healthy volunteers (n = 40, 50% male) recorded 60-s, post-waking HRV with a cost-free mobile application in supine and standing positions for 7 days. The 7-day average and coefficient of variation (CV, reflects daily fluctuation) for the mean RR interval and root mean square of successive differences (LnRMSSD) were assessed. 7-day sleep duration and physical activity profiles were characterized via wrist-worn accelerometer. Subsequent laboratory assessments included aerobic fitness ([Formula: see text]O₂peak) and markers of cardiovascular, metabolic, and psychoemotional health. Associations were evaluated before and after [Formula: see text]O₂peak adjustment.

RESULTS

Bivariate correlations (P < 0.05) demonstrated that higher 7-day averages and/or lower CV values were associated with higher activity levels and superior cardiovascular (lower systolic and diastolic blood pressure [BP] and aortic stiffness [cf-PWV]), metabolic (lower body fat percentage, fasting glucose, and low-density lipoprotein cholesterol [LDL-C]), and psychoemotional health (lower perceived stress) markers, with some variation between sexes and recording position. In males, associations between HRV parameters and cf-PWV remained significant following [Formula: see text]O₂peak adjustment (P < 0.05). In females, HRV parameters were associated (P < 0.05) with numerous cardiovascular (systolic and diastolic BP, cf-PWV) and metabolic (fasting glucose and LDL-C) parameters following [Formula: see text]O₂peak adjustment.

CONCLUSIONS

Higher or more stable supine and standing HRV were generally associated with superior health and lifestyle markers in males and females. These findings lay groundwork for future investigation into the usefulness of self-recorded ultra-short HRV as a health-promoting behavior-modification tool in young adults.

Historical development of accelerometry measures and methods for physical activity and sedentary behavior research worldwide: A scoping review of observational studies of adults

This scoping review identified observational studies of adults that utilized accelerometry to assess physical activity and sedentary behavior. Key elements on accelerometry data collection were abstracted to describe current practices and completeness of reporting. We searched three databases (PubMed, Web of Science, and SPORTDiscus) on June 1, 2021 for articles published up to that date. We included studies of non-institutionalized adults with an analytic sample size of at least 500. The search returned 5686 unique records. After reviewing 1027 full-text publications, we identified and abstracted accelerometry characteristics on 155 unique observational studies (154 cross-sectional/cohort studies and 1 case control study). The countries with the highest number of studies included the United States, the United Kingdom, and Japan. Fewer studies were identified from the continent of Africa. Five of these studies were distributed donor studies, where participants connected their devices to an application and voluntarily shared data with researchers. Data collection occurred between 1999 to 2019. Most studies used one accelerometer (94.2%), but 8 studies (5.2%) used 2 accelerometers and 1 study (0.6%) used 4 accelerometers. Accelerometers were more commonly worn on the hip (48.4%) as compared to the wrist (22.3%), thigh (5.4%), other locations (14.9%), or not reported (9.0%). Overall, 12.7% of the accelerometers collected raw accelerations and 44.6% were worn for 24 hours/day throughout the collection period. The review identified 155 observational studies of adults that collected accelerometry, utilizing a wide range of accelerometer data processing methods. Researchers inconsistently reported key aspects of the process from collection to analysis, which needs addressing to support accurate comparisons across studies.

Mapping features and patterns of accelerometry data on human movement in different age groups and associated health problems: A cross-sectional study

PURPOSE

Human movement is considered one of the important factors for maintaining an independent life. Individuals in different age groups have different characteristics of locomotion patterns and some health conditions can affect or be affected by mobility changes. Few studies clarify or present data about the influence of different ages and biopsychosocial factors on accelerometry features. The aim of this study was to identify characteristics and variables in the frequency signals for different age groups and their relationship with associated health conditions in raw accelerometry data obtained from the use of a triaxial accelerometer during 7 days of activities of daily living.

METHOD

A cross-sectional study was conducted based on the database of the first evaluations of the Epidemiological Study of Movement (EPIMOV) cohort. Frequency, signal amplitude, and entropy accelerometry features of EPIMOV participants who used a triaxial accelerometer for 7 days were extracted. Sociodemographic, clinical, anthropometric and physical activity assessments were also performed. Two-way ANOVA was performed to compare accelerometry features within different age groups. A series of stepwise multiple regressions were performed on accelerometry variables to analyze their relationships with demographic, anthropometric and cardiovascular risk variables.

RESULTS

The sample consisted mostly of female, white, and high school graduates. The most prevalent cardiovascular risk factors were sedentary behavior and obesity. When analyzing the accelerometry variables, it was possible to observe that the entropy feature, and the counts, decrease in the group of older adults, while the feature of harmonic components of gait (frequency × amplitude) increases in the group of older adults. Regarding the amplitude feature, there were no significant differences between the groups. Through stepwise multiple linear regression, it was possible to observe that demographic, anthropometric and cardiovascular risk factors are associated with most accelerometry variables.

CONCLUSION

The results confirm that human movement can be influenced by different ages, sex, demographic, anthropometric and cardiovascular risk factors. Future studies and clinical analyzes can use the methods proposed in this research to adjust movement patterns for sex and different age groups, thus obtaining new interpretations about human movement.

Mediator Effect of Cardiorespiratory Fitness on the Association between Physical Activity and Lung Function in Adults: Cross-Sectional Results from the Epimov Study

We investigated whether cardiorespiratory fitness (CRF) mediates the association between moderate-to-vigorous physical activity (MVPA) and lung function in asymptomatic adults. We examined the cross-sectional results of 1362 adults aged 18–80 years from the Epidemiology and Human Movement Study. Participants were submitted to spirometry to obtain forced vital capacity (FVC) and forced expiratory volume in 1s (FEV1). Additionally, we used cardiopulmonary exercise testing to obtain peak oxygen uptake (V˙O2) as a measure of CRF. Participants used a triaxial accelerometer for 4–7 days to obtain MVPA. Mediation analyses were performed considering the CRF as a mediator, MVPA as an independent variable, and FVC and FEV1 as dependent variables with adjustment for age, sex, and cardiovascular risk score. We aimed to investigate the total (path c) and direct (paths a, b, c’) effects through the regression coefficients. We also examined the indirect effect, which was obtained from the product of the coefficients (path ab). Our sample was composed mainly of overweight and middle-aged women. MVPA was positively related to CRF (path a), as well as CRF and lung function (path b). MVPA also presented a significant positive total effect (path c) in the lung function. However, this relationship became non-significant when CRF was included in the model for both FVC and FEV1 (path c’). We did not observe a direct effect of MVPA on the lung function. In contrast, the indirect effect was significant (path ab). Lastly, CRF mediated 60% of the total effect of MVPA on FVC and 61.9% on FEV1. CRF mediates the relationship between lung function and MVPA in asymptomatic adults. Therefore, our results reinforce the need to include CRF assessment in practice clinical routine and suggest that strategies focusing on CRF might be more promising to prevent respiratory diseases in adults.

Associations between objectively measured physical activity, sedentary time, and cardiorespiratory fitness with inflammatory and oxidative stress markers and heart rate variability

Background

To assess the associations between physical activity (PA) and sedentary time (SEDT) with inflammatory and oxidative stress markers, heart rate variability (HRV) and post-exercise recovery (HRR) controlling for cardiorespiratory fitness (CRF) and potential confounders.

Design and methods

The following data was collected from 44 participants during 2019 (age = 49.5 ± 6.4 years, 66% women): Plasma levels of C-reactive protein (CRP) and cytokines (IL-1β, INF-γ, TNF-α, MCP-1, IL-6, IL-8, IL-10, IL-18, IL-23); catalase (CAT) and glutathione peroxidase (GPX) activities; resting heart (HR) rate for HRV analysis, anthropometric measures, a submaximal cycling test to evaluate CRF with active recovery to assess and HRR (absolute and ΔHR), and 7-day accelerometry.

Results

Women spent significantly more SEDT (p = 0.035), had higher inflammatory markers (IL-6 and TNF) and lower HRV indices [SDNN, LF/HF, SD2 (p > 0.05)]. Significant associations were found between SEDT and markers of inflammation [CRP, B = 0.006, p = 0.001; MCP-1, B = 0.003, p = 0.038]. HRV indices were significantly associated with inflammatory/oxidative stress markers [IL-10 (p = 0.04), GPX (p = 0.014), ln-IL 23 (p = 0.036), CAT (p = 0.026)] while HRR was positively associated with light PA [Δ3 (B = 0.051, p = 0.043), Δ4 (B = 0.062, p = 0.021)] and inversely related to catalase [Δ3 (B = -54.7, p = 0.042), Δ4 (B = -54.1, p = 0.021] and CRP [Δ5 (B = -19.8, p = 0.033)]. Higher CRF showed lower values for TNF-α (p = 0.02) and IL-10 (p = 0.003) and better HRV/HRR indices [RMSSD, PNS, SampEn, SD1 (p < 0.05)].

Conclusions

SEDT had a higher impact on inflammation and autonomic balance, independently of PA levels with differences by sex and CRF. PA appears to be more important for a better HRR. Lower HRV and HRR could be indicative of inflammatory status.

Association of cardiac autonomic modulation with different intensities of physical activity in a small Brazilian inner city: a gender analysis

AbstractPhysical activity has been linked to higher cardiac autonomic modulation. However, it is not clear in the literature which type of intensity of physical activity (sedentary, light, moderate, or vigorous) could be related to better cardiac autonomic modulation and whether this relationship is similar in men and women. The aim of this study was to analyze the relationship between cardiac autonomic modulation and the different intensities of physical activity in men and women. The sample included 100 men and 131 women. Cardiac autonomic modulation was obtained by heart rate variability (SDNN, RMSSD, LF un, HF un, SD1, and SD2). Time spent in different intensities (sedentary, light, moderate, and vigorous intensity physical activity) was measured using a waist-worn accelerometer for seven days. Linear regression was used to verify the relationship between physical activity and cardiac autonomic modulation, considering the adjustment for age, ethnicity, and socioeconomic level. Among men, a significant relationship of moderate intensity was observed with SDNN (β=2.442; p = 0.021) and SD2 (β=2.936, p = 0.028), and of vigorous intensity with SDNN (β=12.826, p = 0.028), RMSSD (β=16.370, p = 0.018), and SD1 (β=12.344, p = 0.025) indices. Among women, light-intensity physical activity was significantly related with LFnu (β= .655, p = 0.005) and HFnu (β= -.590, p = 0.010). Moderate and vigorous physical activity was associated with better cardiac autonomic modulation in men. Light physical activity was associated with lower sympathetic modulation in women.

Association between cardiac autonomic function and physical activity in patients at high risk of sudden cardiac death: a cohort study

Background

High levels of physical activity (PA) and heart rate variability (HRV) are associated with cardiovascular benefits in patients with cardiovascular diseases. HRV, representing cardiac autonomic function, is positively associated with PA. However, the impacts of PA and cardiac autonomic function on cardiovascular outcomes were not analysed in the same study population. This lack of evidence supported our hypothesis that PA might contribute to cardiovascular benefits via enhanced cardiac autonomic function.

Methods

Patients with implantable cardioverter defibrillator (ICD) or cardiac resynchronisation therapy defibrillator (CRT-D) implantation were included from the SUMMIT registry. HRV and PA values were assessed during the first 30–60 days post device implantation using a continuous home monitoring system. Causal mediation analysis was conducted to explore the possible mediation function of HRV in the association of PA with long-term cardiac death and all-cause mortality in patients at a high risk of sudden cardiac death.

Results

Over a mean follow-up period of 47.7 months, 63 cardiac deaths (18.9%) and 85 all-cause death events (25.5%) were observed among 342 patients with ICD/CRT-D implantation. A positive linear association between HRV and PA was demonstrated and the β value of HRV was 0.842 (95% confidence interval [CI]: 0.261–1.425, P = 0.005) in the multiple linear regression analysis. Multivariable Cox proportional hazards analysis revealed that high levels of PA (≥11.0%) and HRV (≥75.9 ms) were independent protective factors against cardiac death (PA: hazard ratio [HR] = 0.273; 95% CI, 0.142–0.526, P < 0.001; HRV: HR = 0.224; 95% CI, 0.103–0.489, P < 0.001) and all-cause mortality (PA: HR = 0.299; 95% CI, 0.177–0.505, P < 0.001; HRV: HR = 0.394; 95% CI, 0.231–0.674, P = 0.001). Causal mediation analysis demonstrated partial mediation effects of PA that were mediated through HRV on cardiac death (mediation proportion = 12.9, 95%CI: 2.2–32.0%, P = 0.006) and all-cause mortality (mediation proportion = 8.2, 95%CI: 1.6–20.0%, P = 0.006).

Conclusions

HRV might be a modest mediator in the association between high levels of PA and the reduced risks of cardiac death and all-cause mortality in ICD/CRT-D recipients. This finding supports that enhanced cardiac autonomic function might be one of the underlying mechanisms by which regular PA contributes to cardiovascular benefits.

Dynamic physiological responses in obese and non-obese adults submitted to cardiopulmonary exercise test

PURPOSE

Obese individuals have reduced performance in cardiopulmonary exercise testing (CPET), mainly considering peak values of variables such as oxygen uptake ([Formula: see text]), carbon dioxide production ([Formula: see text]), tidal volume (Vt), minute ventilation ([Formula: see text]) and heart rate (HR). The CPET interpretation and prognostic value can be improved through submaximal ratios analysis of key variables like [Formula: see text], [Formula: see text], [Formula: see text] [Formula: see text] and oxygen uptake efficiency slope (OUES). The obesity influence on these responses has not yet been investigated. Our purpose was to evaluate the influence of adulthood obesity on maximal and submaximal physiological responses during CPET, emphasizing the analysis of submaximal dynamic variables.

METHODS

We analyzed 1,594 CPETs of adults (755 obese participants, Body Mass Index ≥ 30 kg/m2) and compared the obtained variables among non-obese (normal weight and overweight) and obese groups (obesity classes I, II and III) through multivariate covariance analyses.

RESULT

Obesity influenced the majority of evaluated maximal and submaximal responses with worsened CPET performance. Cardiovascular, metabolic and gas exchange variables were the most influenced by obesity. Other maximal and submaximal responses were altered only in morbidly obese. Only a few cardiovascular and ventilatory variables presented inconsistent results. Additionally, Vtmax, [Formula: see text], Vt/Inspiratory Capacity, Vt/Forced Vital Capacity, Lowest [Formula: see text], [Formula: see text], and the y-intercepts of [Formula: see text] did not significantly differ regardless of obesity.

CONCLUSION

Obesity expressively influences the majority of CPET variables. However, the prognostic values of the main ventilatory efficiency responses remain unchanged. These dynamic responses are not dependent on maximum effort and may be useful in detecting incipient ventilatory disorder. Our results present great practical applicability in identifying exercise limitation, regardless of overweight and obesity.

Classification of cardiorespiratory fitness using the six-minute walk test in adults: Comparison with cardiopulmonary exercise testing

BACKGROUND

The six-minute walk test (6MWT) distance could facilitate the assessment of cardiorespiratory fitness (CRF) in clinical practice as recommended. We aimed to develop a CRF classification using the 6MWT distance in asymptomatic adults considering the treadmill maximum oxygen uptake (V˙O_2max) as the gold standard method.

METHODS

We evaluated V˙O_2max and 6MWT distance in 1295 asymptomatic participants aged 18-80 years (60% women). Age- and sex-related CRF was classified based on the percentiles as very low (<5th percentile), low (5th-25th percentile), regular (26th-50th percentile), good (51st-75th percentile), excellent (76th-95th percentile), and superior (>95th percentile) for both V˙O_2max and 6MWT distance. We investigated the 6MWT distance cut-off (%pred.) with the highest sensitivity and specificity for identifying each V˙O_2max classification.

RESULTS

V˙O_2max declined by 8.7% per decade in both men and women. The 6MWT distance declined by 9.3% per decade in women and 9.5% in men. We formulated age- and sex-related classification tables for CRF using the 6MWT distance. Moreover, the 6MWT distance (%pred.) showed excellent ability to identify very low CRF (6MWT distance ≤ 96%; AUC=0.819) and good ability to differentiate CRF as low (6MWT distance=97%-103%; AUC=0.735), excellent (6MWT distance=107%-109%; AUC=0.715), or superior (6MWT distance>109%; AUC=0.790). It was not possible to differentiate between participants with regular and good CRF.

CONCLUSION

The CRF classification by the 6MWT distance is valid in comparison with V˙O_2max, especially for identifying adults with low CRF. It could be useful in clinical practice for screening and monitoring the cardiorespiratory risk in adults.

ActiGraph and Short-term Heart Rate Variability Study Protocol: Amended for the COVID-19 Pandemic

BACKGROUND

ActiGraph accelerometry is widely used in nursing research to estimate daily physical activity. Heart rate variability (HRV), a measure of autonomic modulation, can be assessed in conjunction with the ActiGraph using a Polar H7 Bluetooth heart rate monitor. There is a paucity of nursing literature to guide nurse researchers' protocol development when using the ActiGraph to assess both physical activity and short-term HRV via its Bluetooth capabilities.

OBJECTIVES

The aim of this study was to describe a standardized research ActiGraph and HRV (ActiGraph HRV) protocol for an ongoing randomized controlled trial to measure physical activity and short-term HRV in patients with ischemic heart disease who report hopelessness.

METHODS

We outline the study protocol for the standardization of reliable and rigorous physical activity and HRV data collection using the ActiGraph wGT3X-BT and Polar H7 Bluetooth heart rate monitor, and data analysis using ActiLife and Kubios software programs.

RESULTS

Sixty-four participants enrolled in the randomized controlled trial to date, and 45 (70.3%) have completed or are actively participating in the study. Heart rate variability data have been collected on 43 of the 45 participants (96%) to date. During the first data collection time point, 42 of 44 participants (95.5%) wore the ActiGraph for a minimum of 5 valid days, followed by 28 of 31 participants (90.3%) and 25 of 26 participants (96.2%) at subsequent data collection time points. The intraclass correlation for physical activity in this study is 0.95 and 0.98 for HRV.

DISCUSSION

Revisions to the protocol were successfully implemented at the onset of the COVID-19 pandemic for data collection using social distancing. The protocol was additionally amended in response to an unanticipated problem with ActiGraph battery life using Bluetooth technology. Use of the ActiGraph HRV protocol has led to a reliable and rigorous measurement of physical activity and HRV for patients with ischemic heart disease who report hopelessness in this randomized controlled trial.

CONCLUSION

We provide an ActiGraph HRV protocol that can be adapted as a model in the development of ActiGraph HRV protocols for future nursing research in community and home-based settings while maximizing social distancing in the current and future pandemics.

Cortical hemodynamics as a function of handgrip strength and cognitive performance: a cross-sectional fNIRS study in younger adults

BACKGROUND

There is growing evidence for a positive correlation between measures of muscular strength and cognitive abilities. However, the neurophysiological correlates of this relationship are not well understood so far. The aim of this study was to investigate cortical hemodynamics [i.e., changes in concentrations of oxygenated (oxyHb) and deoxygenated hemoglobin (deoxyHb)] as a possible link between measures of muscular strength and cognitive performance.

METHODS

In a cohort of younger adults (n = 39, 18-30 years), we assessed (i) handgrip strength by a handhold dynamometer, (ii) short-term working memory performance by using error rates and reaction times in the Sternberg task, and (iii) cortical hemodynamics of the prefrontal cortex (PFC) via functional near-infrared spectroscopy (fNIRS).

RESULTS

We observed low to moderate negative correlations (rp =  ~ - 0.38 to - 0.51; p < 0.05) between reaction time and levels of oxyHb in specific parts of the PFC. Furthermore, we noticed low to moderate positive correlations (rp =  ~ 0.34 to 0.45; p < 0.05) between reaction times and levels of deoxyHb in distinct parts of the PFC. Additionally, higher levels of oxyHb (rp (35) = 0.401; p = 0.014) and lower levels of deoxyHb (rp (34) = - 0.338; p = 0.043) in specific parts of the PFC were linked to higher percentage of correct answers. We also found low to moderate correlations (p < 0.05) between measures of handgrip strength and levels of oxyHb (rp =  ~ 0.35; p < 0.05) and levels of deoxyHb (rp =  ~ - 0.25 to - 0.49; p < 0.05) in specific parts of the PFC. However, there was neither a correlation between cognitive performance and handgrip strength nor did cortical hemodynamics in the PFC mediate the relationship between handgrip strength and cognitive performance (p > 0.05).

CONCLUSION

The present study provides evidence for a positive neurobehavioral relationship between cortical hemodynamics and cognitive performance. Our findings further imply that in younger adults higher levels of handgrip strength positively influence cortical hemodynamics although the latter did not necessarily culminate in better cognitive performance. Future research should examine whether the present findings can be generalized to other cohorts (e.g., older adults).

Heart rate variability as a possible predictor of sport performance in junior rhythmic gymnastics

BACKGROUND: Heart rate variability may reveal sensitive information about the athletes’ physiological adaptation when exercising for sport performance. OBJECTIVE: The aim of this study was to demonstrate whether heart rate variability (HRV) measurements were able to predict sport results and determine which type of measurements, at rest or during routines, were relevant in anticipating the performance. METHOD: Ten female gymnasts, aged 11–14 years old, and 16 age-matched non-active adolescents participated in this study. HRV was measured at rest for 10 minutes and throughout the training routines one week prior to competition. Correlations and multivariate analysis determined the parameters predicting performance. Significance was set at p⩽ 0.05. Results: At rest, the gymnasts displayed higher HRV values than controls. At rest, sympathetic parameters correlated with sport results whereas no correlation was observed during routines. The magnitude of the predictive factors highlighted the importance of Ln SD2 (coefficient =-117, 95CI -130 to -106), Ln RMSSD (coefficient =-24.5, 95CI -29.2 to -19.8), Ln pNN50 (coefficient =-10.7, 95CI -11.5 to -9.9), and Ln Total power (coefficient =-2.5, 95CI -13.4 to -11.5). CONCLUSIONS: HRV at rest may predict results in competition, being a complementary tool for coaches.

Role of Type and Volume of Recreational Physical Activity on Heart Rate Variability in Men

The aim of this study was to investigate the effect of recreational aerobic physical activity (PA) type and volume on heart rate variability (HRV) in Arab men. This was a retrospective, cross-sectional study, and included men (n = 75, age = 37.6 ± 7.1 years, body mass index (BMI) = 26.7 ± 3.1 kg/m²) who were members of a walking group, cycling group, or were inactive controls. Monthly distances from the past three months were obtained from walking and cycling groups, and the volume of PA was classified into three subgroups (high, moderate, low). HRV was measured using a computerized electrocardiographic data acquisition device. R–R interval recordings were performed while participants rested in a motionless supine position. RR intervals were recorded for 15 minutes, and a five-minute segment with minimal ectopic beats and artifacts was selected for HRV analysis. Time-domain parameters included the mean R–R interval, standard deviation of the mean R–R interval (SDNN), and root-mean-squared difference of successive RR intervals (RMSSD). The frequency-domain parameters included high-frequency power (HF), low-frequency power (LF), and LF to HF ratio (LF/HF). Results showed that there were no significant differences between walking, cycling, and control groups for all HRV parameters. Time-domain analyses based on PA volume showed that age-adjusted SDNN for the high-active group was greater than the low-active group (P = 0.03), and RMSSD for the moderate-active group was greater than the control group (P = 0.009). For the frequency domain, LF for the high-active group was greater than the low-active and control groups (P = 0.006), and HF for the moderate-active group was greater than the low-active group (P = 0.04). These data indicate that walking >150 km per month, or cycling >100 km per month at a speed >20 km/h may be necessary to derive cardiac autonomic benefits from PA among Arab men.

Does squatting need attention?-A dual-task study on cognitive resources in resistance exercise

INTRODUCTION

Accumulating evidence shows that acute resistance exercises and long-term resistance training positively influence cognitive functions, but the underlying mechanisms have been rarely investigated. One explanatory approach assumes that the execution of resistance exercises requires higher cognitive processes which, in turn, lead to an 'indirect' training of higher cognitive functions. However, current knowledge on the engagement of higher cognitive functions during the execution of resistance exercises is relatively sparse. Hence, the purpose of this study was to examine to what extent cognitive resources are needed to perform a resistance exercise in the form of barbell back squatting.

METHODS

Twenty-four young adults performed a cognitive task (serial subtraction of 7's) during standing and during barbell back squatting on a Smith machine. The total number and the number of correct responses were analyzed and taken as indicators of the cognitive load imposed by the experimental condition (squatting) and the control condition (standing). Additionally, participants' perceived exertion, mean heart rate, and the number of squats they were able to perform were assessed.

RESULTS

While accuracy scores were found not to be significantly different between conditions, the numbers of total and of correct responses were significantly lower during squatting than during standing. Additionally, during squatting a higher number of total answers was given in the fifth set compared to the first set. We attribute this phenomenon to a learning effect. Furthermore, there was no statistically significant correlation between cognitive measures and perceived exertion.

CONCLUSION

Results suggest that perceived exertion cannot explain the higher dual-task costs observed during squatting. They rather reflect that more cognitive resources are needed to perform low-load barbell back squats than during standing. However, further research is necessary to confirm and generalize these findings.

The relationship between physical activity intensity and domains with cardiac autonomic modulation in adults: An observational protocol study

INTRODUCTION

Cardiac autonomic modulation is an important marker of cardiovascular health and the practice of physical activity is a fundamental tool for good maintenance or increments in this marker. However, it is not clear in the literature whether different intensities and different domains of physical activity are related in the same way to cardiac autonomic modulation.

OBJECTIVES

This randomized epidemiologic study will examine the relationship between cardiac autonomic modulation and different intensities and domains of physical activity in a representative sample of adults.

METHODS

The sample of study will consist of 252 subjects aged from 18 years and above. The sample will be randomized through census sectors in which the neighborhoods, streets, and houses will also be randomized. Cardiac autonomic modulation will be assessed by heart rate variability and the intensity (mild, moderate, intense) of physical activity will be evaluated by means of accelerometers, while the different domains of physical activity (physical activity at work, occupational activities) will be evaluated through a questionnaire. The relationship between cardiac autonomic modulation and different physical activity intensities, as well as the different domains will be analyzed by linear regression, considering a statistical significance of 5% and a 95% confidence interval. This research protocol is registered in ClinicalTrials.gov at number NCT03986879.