Search

Background: This study aims to examine the relationship between resting vagal‐related heart rate variability (HRV) parameters and heart rate (HR) with resting metabolic rate (RMR) and respiratory exchange ratio (RER) in young adults. Methods: A total of 74 young adults (22 ± 2 years old, 51 women) were included in this cross‐sectional study. HRV was assessed using a HR monitor, whereas RMR and RER were determined by indirect calorimetry. Results: Linear regression analyses showed a positive association between HR and RER in women (standardized β = 0.384, p = 0.008), while negative associations were observed between vagal‐related HRV parameters and RER in women (β ranged from −0.262 to −0.254, all p ≤ 0.042). No significant association was found between the abovementioned physiological parameters in men. Conclusion: Here, we show that HR is positively associated with RER in young women but not in men, while vagal‐related HRV parameters are inversely related to RMR, therefore suggesting a potential sexual dimorphism between cardiac rhythm and its relationship with markers of cardiometabolic health status. Trial Registration: ClinicalTrials.gov identifier: NCT02365129. [ABSTRACT FROM AUTHOR]

Predictive equations are widely employed for estimating the volume of oxygen consumption (VO2) while walking, which is ultimately employed to determine energy expenditure and tailor exercise prescription. This study aimed to test the agreement between the measured VO2 and estimated VO2 during a walking protocol on a treadmill at 3.5, 4.5, 5.5, and 6.5 km/h. Thirty‐eight young adults (50% women) participated in this cross‐sectional study. The Omnical (Maastricht Instruments, Maastricht, The Netherlands) and K5 (Cosmed, Rome, Italy) metabolic systems were used to measure VO2. To determine the predictive equations, a comprehensive literature search was conducted using the MEDLINE database from May 2022 to July 2023. Seven predictive equations were found and included for estimating VO2 values. We calculated the mean bias (mean difference between measured VO2 and estimated VO2) obtained at each speed using one‐sample t‐tests. We compared the VO2 measured and estimated values using repeated measures analysis of variance and the Bland–Altman method. One‐sample t‐tests showed that all score errors were different from zero (ranging from 1.1 to 5.4 mL/kg/min). Thus, no predictive equation estimated similar VO2 values in comparison with the Omnical and K5 metabolic systems at all intensities. However, the Weyand equation showed the lowest bias across all intensities (score error of 1.1 mL/kg/min). This study showed a lack of agreement between the Omnical and K5 systems compared to diverse predictive equations specially designed to estimate VO2 during walking. Nevertheless, based on our results, the Weyand equation should be the preferred option. Highlights: The estimated VO2 values derived from all predictive equations showed no agreement with VO2 values measured by the Omnical and K5 metabolic systems, highlighting the importance of taking into account the error introduced by VO2 walking predictive equations when estimating VO2.The Weyand equation presented the lowest bias in comparison to the VO2 measured by the Omnical metabolic cart, which is the gold‐standard metabolic cart (i.e., system of reference).These findings may hold practical implications when transitioning from clinically based programs to exercise interventions tailoring or self‐guided exercise programs in young adults. Moreover, these results can contribute to individualize exercise programs by sport scientists using freely available and affordable tools as predictive equations. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the effects of a 5-week training cessation on the cardiac autonomic response after a 50-m swimming time-trial test. Methods: Twenty trained and highly trained adolescent swimmers (17.1 [2.7] y) performed a 50-m front-crawl all-out test before (visit 1) and after a 5-week training cessation (visit 2). After the warm-up, heart-rate variability (HRV) was recorded in a seated position using a Polar RS800CX heart-rate monitor during the 10 minutes before (preexercise) and immediately after the 50-m front-crawl all-out test (postexercise). Two-way analysis of variance (time × visit) and analysis of covariance were conducted to compute the effect of the 50-m all-out test on vagal-related HRV parameters (mean R-R, standard deviation of R-R intervals [SDNN], square root of the mean squared differences between successive R-R intervals [RMSSD], the percentage number of pairs of adjacent normal R-R intervals differing by more than 50 milliseconds in the entire recording [pNN50], and power in the high frequency [HF]) with Bonferroni post hoc test. Results: All the HRV parameters had a time main effect (P <.05), showing a reduction after the 50 m in both visits (P <.05). All the variables exhibited a visit main effect (P <.05); the preexercise and postexercise mean R-R, natural logarithm SDNN, natural logarithm RMSSD, and natural logarithm HF values declined after the training cessation (P <.05). Natural logarithm pNN50 preexercise values were reduced in visit 2 compared with visit 1 (P <.05). Only mean R-R was further reduced in response to the test in visit 2 compared with visit 1 (P <.05). Conclusions: After 5 weeks of training cessation, all the preexercise and postexercise vagal-related HRV parameters evidenced a reduction, suggesting an impairment in swimmers' physical status. Coaches should be cautious with training loads at the start of the season. [ABSTRACT FROM AUTHOR]

Background: Children with overweight/obesity often exhibit alterations in their plasma protein profiles and reduced heart rate variability (HRV). Plasma proteomics is at the forefront of identifying biomarkers for various clinical conditions. We aimed to examine the association between plasma‐targeted proteomics involved in cardiovascular health and resting vagal‐related HRV parameters in children with overweight/obesity. Methods: Forty‐four children with overweight/obesity (10.2 ± 1.1 years old; 52% boys) participated in the study. Olink's technology was used to quantify 92 proteins involved in cardiovascular health. HRV was measured using a heart rate monitor (Polar RS800CX). Four resting vagal‐related HRV parameters were derived in time‐ and frequency‐domain. Results: Eight proteins (KIM1, IgG Fc receptor II‐b, IDUA, BOC, IL1RL2, TNFRSF11A, VSIG2, and TF) were associated with at least one out of the four vagal‐related HRV parameters (β values ranging from −0.188 to 0.288; all p <.05), while KIM1, IDUA, and BOC associated with ≥ three vagal‐related HRV parameters. Multiple hypothesis testing corrections did not reach statistical significance (false discovery rate [FDR >0.05]). Conclusion: Plasma‐targeted proteomics suggested novel biomarkers for resting vagal‐related HRV parameters in children with overweight/obesity. Future studies using larger cohorts and longitudinal designs should confirm our findings and their potential clinical implications. [ABSTRACT FROM AUTHOR]

Objective: To determine differences in resting heart rate variability (HRV) and heart rate (HR) between young adults with normal‐weight obesity (NWO) and normal‐weight lean (NWL). Methods: A total of 65 normal‐weight individuals (18–25 years old, 50 women, body mass index 18.5 to 24.9 kg/m2) were included in this cross‐sectional study. Body fat percentage was determined using a whole‐body dual energy x‐ray absorptiometry scanner. Resting HRV and HR were assessed with the Polar RS800CX. Forty‐one participants were classified as NWO and 24 NWL using cutoff points for body fat percentage (33.3% for women and 23.1% for men). Results: There were no differences in HRV between NWO and NWL groups (all p >.05). HR was higher in NWO (mean 70 beats per minute [bpm], standard deviation [SD] 8) than in NWL adults (mean 65 bpm, SD 10), the adjusted mean difference 5 bpm (95% CI, 0 to 10 bpm). Conclusion: HR is a noninvasive biomarker and relatively cheap, fast, and easy to measure that could detect "apparently healthy" young individuals with an adverse cardiovascular disease risk profile despite presenting a normal body weight. [ABSTRACT FROM AUTHOR]

Concurrent training has been postulated as an appropriate time‐efficient strategy to improve physical fitness, yet whether the exercise‐induced adaptations are similar in men and women is unknown. An unblinded randomized controlled trial was conducted to investigate sex‐specific dose–response effects of a 24‐week supervised concurrent exercise training program on cardiorespiratory fitness and muscular strength in young adults. One hundred and forty‐four sedentary adults aged 18–25 years were assigned to either (i) a control group (n = 54), (ii) a moderate intensity exercise group (MOD‐EX, n = 46), or (iii) a vigorous intensity exercise group (VIG‐EX, n = 44) by unrestricted randomization. Cardiorespiratory fitness (VO2max), hand grip strength, and one‐repetition maximum of leg press and bench press were evaluated at baseline and after the intervention. A total of 102 participants finished the intervention (Control, n = 36; 52% women, MOD‐EX, n = 37; 70% women, and VIG‐EX, n = 36; 72% women). In men, VO2max significantly increased in the MOD‐EX (~8%) compared with the control group and in the VIG‐EX group after the intervention (~6.5%). In women, VO2max increased in the MOD‐EX and VIG‐EX groups (~5.5%) compared with the control group after the intervention. There was a significant increment of leg press in the MOD‐EX (~15.5%) and VIG‐EX (~18%) groups compared with the control group (~1%) in women. A 24‐week supervised concurrent exercise was effective at improving cardiorespiratory fitness and lower body limbs muscular strength in young women—independently of the predetermined intensity—while only at moderate intensity improved cardiorespiratory fitness in men. [ABSTRACT FROM AUTHOR]