Exercise In Healthy Young Adults Research Articles

Comparison of sEMG activity of submental muscles between the head-lift exercise, tongue-press exercise and the head extension tongue-press exercise in healthy young adults.

Swallowing is a complex function that requires precise coordination between different muscles. Weakness in submental muscles can lead to complications such as pharyngeal residue and aspiration. Therefore, exercise interventions targeting these muscles, such as the Head-Lift Exercise (HLE), are clinically important but pose challenges. This study aimed to compare the myoelectric activity of submental muscles during traditional Head-Lift Exercise (HLE), Tongue-Press Exercise (TPE) and Head Extension Tongue-Press Exercise (HETPE), providing potential alternatives to HLE. Thirty healthy volunteers (22 females and 8 males, mean age 25.63 ± 5.27 years) participated in this cross-sectional study. Surface electromyography (sEMG) recorded activity of the submental muscles bilaterally during HLE, TPE and HETPE. Participants performed each manoeuvre for 14 s, repeated three times in a counterbalanced order. Statistical analyses assessed differences in mean, maximum and median frequency of the sEMG signals among manoeuvres using repeated-measures analysis of variance (RM-ANOVA). The experienced irritation levels by participants during manoeuvres were also compared by the Friedman test. HETPE exhibited significantly higher maximum sEMG activity compared to HLE and TPE (p < .05). Mean sEMG activity was significantly increased during HETPE compared to TPE. Median frequency was significantly lower during HETPE compared to the two other exercises, indicating greater muscle fatigue. Participants reported similar levels of irritation for HLE and HETPE, and significantly lower levels during TPE. These results indicate that HETPE is effective in activating and strengthening submental muscles, potentially serving as a viable alternative to HLE without added difficulty. Further research is recommended to assess the long-term impacts on swallowing physiology in patients with dysphagia.

Blood pressure and heart rate variability to assess autonomic response to an acute bout of high intensity interval exercise in healthy young adults.

Autonomic nervous system (ANS) activity causes acute variations in blood pressure (BP) and heart rate (HR). These systems are challenged during high intensity interval exercise (HIIE). However, BP variability (BPV) and HR variability (HRV) response to HIIE is unknown. We characterized BPV and HRV during an acute HIIE bout using spectral low frequency [LF] and high frequency [HF] domains. We hypothesized that BPV would increase and HRV would decrease during high-intensity and active-recovery of HIIE compared to baseline [BL] and BPV would reduce and HRV would increase during cool down, post-HIIE, and 30 min post-HIIE compared to BL. HIIE involved 10 min of alternating high-intensity and active-recovery (approximately 70% and 10% of Wattmax) on a recumbent stepper. We did a secondary analysis on 23 datasets. The participants were 25 ± 1.5 years, 48% females. Our results showed high-intensity BPV LF was not significantly different from BL while HF increased. HRV LF and HF decreased compared to BL. During active-recovery, LF and HF for BPV and HRV increased greater than high-intensity. HRV LF and HF returned to BL after 30 min of recovery, whereas BPV HF was higher compared to BL. The rapid switching during HIIE uniquely modulates cardiovascular and ANS.

Rapid adjustments to autonomic control of cardiac rhythm at the onset of isometric exercise in healthy young adults.

Sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) influences on cardiac rhythm at the onset of exercise, a time of rapid autonomic adjustments, are clinically important areas of investigation. Continuous wavelet transform (CWT) involves time-frequency-based heart rate variability (HRV) analysis allowing investigation of autonomic influences on cardiac rhythm during short durations of exercise. Therefore, the purpose of this study was to characterize SNS and PNS influences on cardiac rhythm at the onset of isometric exercise in healthy young adults. CWT analysis was retrospectively applied to R-R interval data (electrocardiogram) previously collected from 14 healthy young adults (26 ± 2 years) who performed 30-s, one-legged, isometric, calf exercise at 70% maximal voluntary contraction (MVC; 70% MVC trial) or rested (0% MVC trial). Absolute and normalized low-frequency (aLF, nLF; 0.04-0.15 Hz) and high-frequency (aHF, nHF; 0.15-0.4Hz) bands and LF/HF were used to analyze one 30-s baseline period and six 5-s time windows during the 30-s exercise (70% MVC) or rest (0% MVC). Statistical analysis involved two-way analysis of variance with post-hoc analysis. aHF, aLF, LF/HF, nHF, and nLF displayed a trial-time interaction (all p ≤ 0.027). In the 70% compared to the 0% MVC trial, aHF and nHF were lower after 5-30 s (all p ≤ 0.040), aLF was lower after 20-30 s (all p ≤ 0.011) and LF/HF and nLF were higher after 5-20 s (all p ≤ 0.045). These results indicate the reduction of the PNS influence on cardiac rhythm begins sooner than the augmentation of the SNS influence at the onset of isometric exercise in healthy young adults.

Repeatability of Brain Activity as Measured by a 32-Channel EEG System during Resistance Exercise in Healthy Young Adults.

Electroencephalography (EEG) is attracting increasing attention in the sports and exercise fields, as it provides insights into brain behavior during specific tasks. However, it remains unclear if the promising wireless EEG caps provide reliable results despite the artifacts associated with head movement. The present study aims to evaluate the repeatability of brain activity as measured by a wireless 32-channel EEG system (EMOTIV flex cap) during resistance exercises in 18 apparently healthy but physically inactive young adults (10 men and 8 women). Moderate-intensity leg press exercises are performed with two evaluations with 48 h. between. This intensity allows enough time for data analysis while reducing unnecessary but involuntary head movements. Repeated measurements of EEG during the resistance exercise show high repeatability in all frequency bands, with excellent ICCs (>0.90) and bias close to zero, regardless of sex. These results suggest that a 32-channel wireless EEG system can be used to collect data on controlled resistance exercise tasks performed at moderate intensities. Future studies should replicate these results with a bigger sample size and different resistance exercises and intensities.

Hemodynamic responses during inspiratory muscle exercise in healthy young adults

RESUMO A literatura carece de um consenso sobre respostas hemodinâmicas durante o exercício muscular inspiratório (EMI). Este estudo buscou avaliar e comparar as respostas hemodinâmicas durante uma sessão de EMI com e sem carga resistiva. Para tanto, 15 homens sedentários foram submetidos a duas sessões randomizadas de EMI: 40% da pressão inspiratória máxima (EMI 40%) e sem carga resistiva (sham), realizadas por dois minutos em oito sessões e com intervalos de um minuto. A pressão arterial sistólica (PAS), pressão arterial diastólica (PAD), pressão arterial média (PAM), resistência periférica total (RPT), volume sistólico (VS), débito cardíaco (DC) e frequência cardíaca (FC) foram medidos por fotopletismografia infravermelha digital por cinco minutos basais e durante as sessões de EMI. Anova de uma via e o teste t de Student para dados pareados foram usados para analisar a resposta hemodinâmica e os valores delta entre as sessões. O tamanho do efeito foi avaliado pelo d de Cohen. Adotou-se nível de significância de 5%. As respostas de PAS (sham: ∆−1±2 vs. 40%: ∆−4±2mmHg, p=0,27), PAD (sham: ∆2±1 vs. 40%: ∆1±2mmHg, p=0,60) e PAM (sham: ∆2±1 vs. 40%: ∆0±2mmHg, p=0,28) foram semelhantes entre as sessões. Os aumentos da FC foram maiores na sessão de EMI 40% do que nas sessões sham (sham: ∆9±2 vs. 40%: ∆3±2bpm, p=0,001). O VS diminuiu exclusivamente durante a sessão sham mas a resposta foi semelhante entre as sessões (sham: ∆−2±2 vs. EMI 40%: ∆−6±2ml, p=0,13). Ambas as sessões não causaram alteração nas variáveis PAS, PAD, PAM, DC e RPT, mas notamos um aumento maior da FC na sessão EMI 40%. Apenas a sessão sham reduziu o VS.

High-Dose Nitrate Supplementation Attenuates the Increased Blood Pressure Responses to Isometric Blood Flow Restriction Exercise in Healthy Males.

The effect of nitrate (NO3−) supplementation on blood pressure (BP) responses during large muscle mass isometric and ischaemic exercise in healthy young adults is unclear. The aim of the present study was to assess the effect of 5-day supplementation of NO3− on BP responses during a short isometric contraction and a sustained ischaemic contraction. In a randomised, double-blinded, crossover design, 14 healthy active young adults underwent BP measurements after 5 days of either NO3− (NIT) or placebo (PLA) supplementation. Beat-by-beat BP was measured at pre- and post-exercise rest, and during a short (20 s) isometric contraction at 25% maximal strength and throughout a sustained ischaemic contraction. Plasma nitrite (NO2−) concentration increased significantly after NO3− supplementation compared to placebo (475 ± 93 nmol·L−1 vs. 198 ± 46 nmol·L−1, p < 0.001, d = 3.37). Systolic BP was significantly lower at pre- (p = 0.051) and post-exercise rest (p = 0.006), during a short isometric contraction (p = 0.030), and throughout a sustained ischaemic contraction (p = 0.040) after NO3− supplementation. Mean arterial pressure was significantly lower at pre- (p = 0.004) and post-exercise rest (p = 0.043), during a short isometric contraction (p = 0.041), and throughout a sustained ischaemic contraction (p = 0.021) after NO3− supplementation. Diastolic BP was lower at pre-exercise rest (p = 0.032), but not at post-exercise rest, during a short isometric contraction, and during a sustained ischaemic contraction (all p > 0.05). Five days of NO3− supplementation elevated plasma NO2− concentration and reduced BP during a short isometric contraction and a sustained ischaemic contraction in healthy adults. These observations indicate that multiple-day nitrate supplementation can decrease BP at rest and attenuate the increased BP response during isometric exercise. These findings support that NO3− supplementation is an effective nutritional intervention in reducing SBP and MAP in healthy young males during submaximal exercise.

Effects of pre-exercise H2 inhalation on physical fatigue and related prefrontal cortex activation during and after high-intensity exercise.

Objective: In this study, we examined the effects of pre-exercise H2 gas inhalation on physical fatigue (PF) and prefrontal cortex (PFC) activation during and after high-intensity cycling exercise. Methods: Twenty-four young men completed four study visits. On the first two visits, the maximum workload (Wmax) of cycling exercise of each participant was determined. On each of the other two visits, participants inhaled 20 min of either H2 gas or placebo gas after a baseline test of maximal voluntary isometric contraction (MVIC) of thigh. Then participants performed cycling exercise under their maximum workload. Ratings of perceived exertion (RPE), heart rate (HR) and the PFC activation by using functional near-infrared spectroscopy (fNIRS) was measured throughout cycling exercise. The MVIC was measured again after the cycling. Results: It was observed that compared to control, after inhaling H2 gas, participants had significantly lower RPE at each workload phase (p < 0.032) and lower HR at 50% Wmax, 75% Wmax, and 100% Wmax during cycling exercise (p < 0.037); the PFC activation was also significantly increased at 75 and 100% Wmax (p < 0.011). Moreover, the H2-induced changes in PF were significantly associated with that in PFC activation, that is, those who had higher PFC activation had lower RPE at 75% Wmax (p = 0.010) and lower HR at 100% Wmax (p = 0.016), respectively. Conclusion: This study demonstrated that pre-exercise inhalation of H2 gas can alleviate PF, potentially by maintaining high PFC activation during high-intensity exercise in healthy young adults.

Low Vitamin D Status Relates to the Poor Response of Peripheral Pulse Wave Velocity Following Acute Maximal Exercise in Healthy Young Men.

The primary objective of this study was to determine the effects of vitamin D levels on peripheral pulse wave velocity (pPWV) following acute maximal exercise in healthy young adults. Fifty male healthy adults from National Chung Cheng University participated in the study. Participants were divided into the 25-hydroxyvitamin D (25(OH)D) sufficiency group (n = 28, 25(OH)D ≥ 50 nmol/L) and deficiency group (n = 22, 25(OH)D < 50 nmol/L). The acute maximal exercise was performed using an incremental cycling test to exhaustion. Additionally, the pPWV and blood pressure were obtained at rest and 0, 15, 30, 45, 60 min after acute maximal exercise. The results show that 25(OH)D deficiency group had higher pPWV at post-exercise (5.34 ± 0.71 vs. 4.79 ± 0.81 m/s, p < 0.05), post-exercise 15 min (5.13 ± 0.53 vs. 4.48 ± 0.66 m/s, p < 0.05) and post-exercise 30 min (5.26 ± 0.84 vs. 4.78 ± 0.50 m/s, p < 0.05) than the sufficiency group. Furthermore, there was a significant inverse correlation between 25(OH)D levels and pPWV following acute maximal exercise. Our study demonstrated that low vitamin D status relates to the poor response of pPWV following maximal exercise in healthy young men. Vitamin D deficiency may increase the risk of incident cardiovascular events after acute exhaustive exercise, even in healthy and active adults.

Rapid Adjustments to Autonomic Control of Cardiac Rhythm at the Onset of Exercise in Healthy Young Adults

Changes in sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) influences on cardiac rhythm during exercise can be reflected in time‐ and frequency‐based heart rate variability (HRV) analysis and differ depending on exercise intensity. However, the SNS and PNS contributions to cardiac rhythm at the onset of exercise has not been investigated due to the complexity of applying HRV analysis during short durations of exercise. Continuous wavelet transform (CWT) combines time‐ and frequency‐based analyses to allow autonomic influences on beat‐to‐beat fluctuations in R‐R intervals (RRI) to be captured in rapidly changing signals, such as at the onset of exercise. Therefore, the objective of this study was to characterize the rapid autonomic adjustments influencing cardiac rhythm at the onset of exercise in healthy young adults. This study was a secondary analysis of data previously collected from 14 healthy young adults (26 ± 2 years, 6 male/8 female) during two trials: a 5‐minute baseline followed by performance of isometric, right‐calf exercise at 70% maximal voluntary contraction (MVC) for 30 seconds (70% MVC) or continued rest (0% trial). Heart rate was continuously measured using a three‐lead electrocardiogram from which RRIs were derived. Analysis involved applying CWT to the RRI data using low‐frequency (LF; 0.04‐0.15 Hz) and high‐frequency (HF; 0.15‐0.4 Hz) bands for HRV analysis. Log‐transformed absolute (aLF, aHF) and normalized (nLF, nHF) LF and HF time‐frequency bands and their ratio (LF/HF) were calculated for each time period (one baseline time period – 0‐30 seconds, and six rest/exercise time periods – 300‐305, 305‐310, 310‐315, 315‐320, 320‐325, and 325‐330 seconds) in each trial (0% and 70% MVC). Group means and standard deviations for all five variables were calculated for each time period in each trial. Statistical analysis involved two‐way repeated measures analysis of variance with post hoc analysis involving paired t tests and a Holm‐Bonferroni correction with statistical significance set at P &lt; 0.05. It was hypothesized that the SNS influence on cardiac rhythm, measured by LF and LF/HF, would increase while the PNS influence on cardiac rhythm, measured by HF, would decrease at the onset of exercise in healthy young adults. There was a significant trial‐time interaction for aHF, aLF, and LF/HF (P &lt; 0.001, P = 0.003, and P = 0.027, respectively). aHF was lower during 5‐30 seconds (all P ≤ 0.025), aLF was lower during 20‐30 seconds (all P ≤ 0.011), and LF/HF was higher during 5‐20 seconds (all P ≤ 0.045) following the start of exercise in the 70% MVC trial compared to the 0% trial. There were significant effects of trial for aHF, nLF, nHF, and LF/HF (all P ≤ 0.014) and time for aHF and LF/HF (all P ≤ 0.011). These results indicate that the reduction of the PNS influence on cardiac rhythm begins sooner than the augmentation of the SNS influence on cardiac rhythm at the onset of exercise in healthy young adults.

Sex Differences In Pulse Pressure Amplification Responses During Different Intensities Of Isometric Handgrip Exercise In Healthy Young Adults

Pulse pressure amplification (PPA) refers to the elevated pulse pressure (PP) in the peripheral arteries relative to the central arteries and is the result of differences in vascular tone and time-dependent forward and reflected wave coupling within the arterial tree. PPA has been shown to predict sex differences in cardiovascular (CV) and all-cause mortality risk in middle-aged and older populations. Although PPA has been shown to increase during dynamic exercise in men, no study has investigated sex differences in PPA response to different intensities of isometric handgrip (IHG) exercise. METHODS: A total of 14 healthy young adults, 7 men (27 1 years) and 7 women (25 1 years) participated in the study. Each participant engaged in IHG exercises for 2-minutes at 20%, 30%, and 40% of their maximum voluntary contraction (MVC). Using a SphygmoCor device, radial artery tonometry was performed continuously throughout the experiment to collect PPA and other relevant peripheral and central hemodynamic data derived from the radial and estimated aortic waveforms. PPA is represented as a ratio of peripheral PP to central PP (radial PP/aortic PP). RESULTS: Baseline PPA values for all three intensities were not different between men and women (all P > 0.005). ΔPPA from baseline had significant group by time interaction during static HG exercise at 20% (P = 0.0418) and 30% (P = .0495) of MVC but not at 40% of MVC (P = 0.6701). Initially, ΔPPA increased in men and women from baseline to 30(s) at 20%, 30%, and 40% of MVC except in women at 30% of MVC. From 30(s) to 120(s), men and women had a decrease in ΔPPA for all HG intensities. The largest sex differences in ΔPPA observed at 120(s) at 20% and 30% of MVC trend toward significance (P = 0.1399 and P = 0.0517, respectively). CONCLUSIONS: The data support that there are intensity-dependent sex differences in PPA responses to static exercise. Supported by AHA Undergraduate Student Fellowship (Eckenrode), NIH P01 HL134609 (Sinoway), and UL1 TR002014 (Sinoway)

Similar improvements in cognitive inhibitory control following low-intensity resistance exercise with slow movement and tonic force generation and high-intensity resistance exercise in healthy young adults: a preliminary study

This study compared the effects of low-intensity resistance exercise with slow movement and tonic force generation (ST-LRE) and high-intensity resistance exercise (HRE) on post-exercise improvements in cognitive inhibitory control (IC). Sixteen young males completed ST-LRE and HRE sessions in a crossover design. Bilateral knee extensor ST-LRE and HRE (8 repetitions/set, 6 sets) were performed with 50% of one-repetition maximum with slow contractile speed and 80% of one-repetition maximum with normal contractile speed, respectively. The IC was assessed using the color–word Stroop task at six time points: baseline, pre-exercise, immediate post-exercise, and every 10 min during the 30-min post-exercise recovery period. The blood lactate response throughout the experimental session did not differ between ST-LRE and HRE (condition × time interaction P = 0.396: e.g., mean ± standard error of the mean; 8.1 ± 0.5 vs. 8.1 ± 0.5 mM, respectively, immediately after exercise, P = 0.983, d = 0.00). Large-sized decreases in the reverse-Stroop interference scores, which represent improved IC, compared to those before exercise (i.e., baseline and pre-exercise) were observed throughout the 30 min post-exercise recovery period for both ST-LRE and HRE (decreasing rate ≥ 38.8 and 41.4%, respectively, all ds ≥ 0.95). The degree of post-exercise IC improvements was similar between the two protocols (condition × time interaction P = 0.998). These findings suggest that despite the application of a lower exercise load, ST-LRE improves post-exercise IC similarly to HRE, which may be due to the equivalent blood lactate response between the two protocols, in healthy young adults.

Lower-body dynamic exercise reduces wave reflection in healthy young adults.

What is the central question of this study? There is a paradoxical reduction in augmentation index during lower-body dynamic (LBD) exercise in the face of an increase in central pressure. To determine causality, the amplitudes of forward and backward pressure waves were assessed separately using wave separation analysis. What is the main finding and its importance? Reflection magnitude decreased during LBD exercise in healthy young adults and was attributable to an increased forward pressure wave amplitude and decreased backward pressure wave amplitude. This vasoactive response might limit the adverse effects of wave reflection during LBD exercise, optimizing ventricular-arterial interactions. Acute lower-body dynamic (LBD) exercise decreases surrogate measures of wave reflection, such as the augmentation index. However, the augmentation index is influenced by the combined effects of wave reflection timing, magnitude and other confounding factors external to wave reflection, which make it difficult to discern the origin of changes in surrogate measures. The relative contributions of forward (Pf) and backward (Pb) pressure wave amplitudes to central pressure can be determined by wave separation analysis. Reflection magnitude (RM=Pb/Pf) and the timing of apparent wave reflection return can also be determined. We tested the hypothesis that acute LBD exercise decreases RM and reflected wave transit time (RWTT). Applanation tonometry was used to record radial artery pressure waveforms in 25 adults (24 ± 4 years of age) at baseline and during light-, moderate- and vigorous-intensity exercise. Wave separation analysis was conducted offline using a personalized physiological flow wave to determine Pf, Pb, RM and RWTT. The RM decreased during all intensities of exercise compared with baseline (all P<0.001; baseline, 43 ± 5%; light, 33 ± 6%; moderate, 23 ± 7%; vigorous, 17 ± 5%). The reduction in RM was attributable to the combined effect of increased Pf and decreased Pb during exercise. The RWTT decreased during all intensities of exercise compared with baseline (all P<0.04; baseline, 156 ± 17ms; light, 144 ± 15ms; moderate, 129 ± 16ms; vigorous, 121 ± 17ms). Lastly, in a stepwise multilinear regression, Pf, but not Pb and RWTT, contributed to increased central pulse pressure during LBD exercise. These data show that wave reflection decreased and that central pulse pressure is most influenced by Pf during LBD exercise.

Effect of hip abduction angle on trunk muscle activation during plank exercise

Background and objectives: The purpose of this study was to investigate the effect of hip joint abduction an-gle change on trunk muscle activities during plank exercise. Materials and methods: This study was conducted with 34 subjects but 4 subjects dropped out during the measurement and 30 subjects completed the study. Muscle activities were measured while performing plank exercise with hip joint abduction angles at 0, 15, 30, or 45 degrees. Electrodes were placed on four muscles: rectus abdominis, external oblique, internal oblique, and erector spinae muscles. Two-way repeated measures ANOVA was used to analyze the interaction between hip joint abduction angle and trunk muscle activities. One-way repeated measures ANOVA was performed to determine trunk muscle activities of each muscle at each hip joint abduction angle. Eta-squared (η2) values were used to determine effect sizes. Results: A significant interaction was found between hip joint abduction angle and muscle type (p &lt; 0.05). Hip joint abduction angle was significantly associated with rectus abdominis and erector spinae activities (p &lt; 0.05). Conclusions: When the hip joint is abducted during plank exercise in healthy young adults, the muscle activities of rectus abdominis and erector spinae are inversely proportional to hip joint abduction angles.

Exercise-related blood pressure response is related to autonomic modulation in young adults: A new extension study.

BACKGROUND: The delayed blood pressure recovery (BPR) at post-exercise has been in association with a major risk of cardiovascular disease and death.OBJECTIVE: The study focused on evaluating the systolic and diastolic blood pressure recovery (SBPR, DBPR) and the autonomic modulation following treadmill exercise in healthy young adults. Although considerable literature had been published about BPR and HRV, the association between BPR and ultra-short-term HRV has not yet been completely described.METHODS: Fifteen subjects performed exercise with three different intensities on a treadmill, the speed was 6 km/h, 9 km/h, 12 km/h, respectively. SBP and DBP was measured per 30 s in each trial. The synchronous 5-min electrocardiogram (ECG) signals were recorded and HRV parameters including SDNN, RMSSD, SDNN/RMSSD, SD1, SD2 and SD1/SD2 were calculated every 30 s periods in 5 min ECG signals to match the corresponding BPR.RESULTS: The intraclass correlation coefficient (ICC) values and the Bland-Altman plots indicated good consistency and repeatability between HRV and HRV at three post-exercise trials, with most ICC values 0.75. Besides, SBPR and DBPR generally decreased and returned to the Rest level in 5 mins. The Spearman correlation coefficients showed strong relationships between BPR and HRV sympathetic-vagal balance parameters, i.e., ratio SDNN/RMSSD and ratio SD1/SD2.CONCLUSIONS: These observations represented a new insight into the cardiovascular regulation at post-exercise, which could contribute to physical exercise areas in the future.

Choroidal Thickness and Volume Modifications Induced by Aerobic Exercise in Healthy Young Adults

Introduction: Our aim was to evaluate the changes in choroidal thickness (CT) and volume (CV) following aerobic physical exercise in healthy young adults. Methods: This study included 72 eyes from healthy volunteers between 22 and 37 years old. Using the International Physical Activity Questionnaire, total physical activity was computed. Measurements using an autorefractometer, ocular biometry, and spectral-domain optical coherence tomography using the Enhanced Depth Imaging protocol were taken. OCT was performed as a baseline measurement and after performing 10 min of dynamic physical exercise (3 and 10 min post-exercise). The choroidal layer was manually segmented, and the CT and CV in different areas from the Early Treatment Diabetic Retinopathy Study grid were obtained. Results: In healthy adults, at 3 min post-exercise, CT was higher in the subfoveal, the 3-mm nasal, and the 6-mm superior areas. Between 3 and 10 min post-exercise, the CT was reduced in all areas, and in some areas, the values were even smaller than the baseline measurements. The CV values showed changes after exercise similar to those of thickness. The total CV recovery after exercise was related to sex and physical activity level. Conclusion: Individuals with higher physical activity habits had greater CV at rest than those with lower physical activity levels. During exercise, healthy young people adjust CT and CV. At 3 min post-exercise, CT and CV increase. Women and individuals with greater physical activity levels reduce their total CV more than others during recovery.

Acute FeNO and Blood Pressure Responses to Air Pollution Exposure in Young Adults during Physical Activity.

During physical exercise, the absorbed dose of air pollutants increases. Acute effects of exposure to air pollutants during exercise in healthy young adults remain poorly documented. The aim of this study was to assess the acute responses in fractionated exhaled nitric oxide (FeNO) and blood pressure to air pollution exposure during exercise in young adults with different physical activity levels (low or high). In this study, 76 healthy university students participating in physical activity classes (low level of physical activity) and attending sports training (high level of physical activity) completed two indoor exercise trials when air pollutant concentrations were high (exposure trial) and when the quality of the air was good (control trial). We monitored indoor particulate matter with diameter <10 µm and <2.5 µm (PM10 and PM2.5) and outdoor PM10, nitric oxides (NO2, NOx, NO), and sulfur dioxide (SO2) concentrations. Systolic and diastolic blood pressure (SBP and DBP), heart rate (HR), oxygen saturation (SpO2), and FeNO were measured at baseline and after 45–60 min of physical activity. There were no significant differences between physiological responses to training performed under different exposure conditions in blood pressure, HR, and SpO2. Significant positive correlations between post-exercise ΔFeNO during exposure trials and ambient air pollutants were found. FeNO increase during the exposure trial was associated with a higher physical activity level and higher outdoor PM10 and NO2 concentrations. In young and healthy adults, some differences in physiological responses to physical activity between polluted and control environments could be observed. Participants with a high physical activity level were more likely to have an increase in FeNO after exercise in a polluted environment but not after the control exercise trials.

Dynamic and isometric handgrip exercise increases wave reflection in healthy young adults.

Early return and increased magnitude of wave reflection augments pulsatile load, wastes left ventricular effort, and is associated with cardiovascular events. Acute handgrip (HG) exercise increases surrogate measures of wave reflection such as augmentation index. However, augmentation index does not allow distinguishing between timing versus magnitude of wave reflection and is affected by factors other than wave reflection per se. Wave separation analysis decomposes central pressure into relative contributions of forward (Pf) and backward (Pb) pressure wave amplitudes to calculate reflection magnitude (RM = Pb/Pf) and determine the timing of apparent wave reflection return. We tested the hypothesis that acute dynamic and isometric HG exercise increases RM and decreases reflected wave transit time (RWTT). Applanation tonometry was used to record radial artery pressure waveforms in 30 adults (25 ± 4 yr) at baseline and during dynamic and isometric HG exercise. Wave separation analysis was performed offline using a physiological flow wave to derive Pf, Pb, RM, and RWTT. We found that RM increased during dynamic and isometric HG exercise compared with baseline (P = 0.04 and P < 0.01, respectively; baseline 40 ± 5, dynamic 43 ± 6, isometric 43 ± 7%). Meanwhile, RWTT decreased during dynamic and isometric HG exercise compared with baseline (P = 0.03 and P < 0.001, respectively; baseline 164 ± 23, dynamic 155 ± 23, isometric 148 ± 20 ms). Moreover, the changes in RM and RWTT were not different between dynamic and isometric HG exercise. The present data suggest that wave reflection timing (RWTT) and magnitude (RM) are important factors that contribute to increased central blood pressure during HG exercise.NEW & NOTEWORTHY This study demonstrated that wave reflection magnitude is increased while reflected wave transit time is decreased during handgrip exercise in healthy young adults. The larger backward pressure waves and earlier return of these pressure waves were not different between dynamic and isometric handgrip exercise. These acute changes in wave reflection during handgrip exercise transiently augment pulsatile load.

Vascular function is related to blood flow during high-intensity, but not low-intensity, knee extension exercise.

While vascular function, assessed as the ability of the vasculature to dilate in response to a stimulus, is related to cardiovascular health, its relationship to exercise hyperemia is unclear. This study sought to determine if blood flow during submaximal and maximal exercise is related to vascular function. Nineteen healthy adults completed multiple assessments of vascular function specific to the leg, including passive leg movement (PLM), rapid onset vasodilation (ROV), reactive hyperemia (RH), and flow-mediated dilation (FMD). On a separate day, exercise blood flow (Doppler ultrasound) was assessed in the same leg during various intensities of single-leg, knee-extension (KE) exercise. Vascular function, determined by PLM, ROV, and RH, was related to exercise blood flow at high intensities, including maximum work rate (WRmax) (r = 0.58-0.77, P < 0.001), but not low intensities, like ~21% WRmax (r = 0.12-0.34, P = 0.12-0.62). Relationships between multiple indices of vascular function and peak exercise blood flow persisted when controlling for quadriceps mass and exercise work rate (P < 0.05), indicating vascular function is independently related to the blood flow response to intense exercise. When divided into two groups based upon the magnitude of the PLM response, subjects with a lower PLM response exhibited lower exercise flow at several absolute work rates, as well as lower peak flow (P < 0.05). In conclusion, leg flow during dynamic exercise is independently correlated with multiple different indices of microvascular function. Thus microvascular function appears to modulate the hyperemic response to high-intensity, but not low-intensity, exercise.NEW & NOTEWORTHY While substantial evidence indicates that individuals with lower vascular function are at greater risk for cardiovascular disease, with many redundant vasodilator pathways present during exercise, it has been unclear if low vascular function actually impacts blood flow during exercise. This study provides evidence that vascular function, assessed by multiple noninvasive methods, is related to the blood flow response to high-intensity leg exercise in healthy young adults. Importantly, healthy young adults with lower levels of vascular function, particularly microvascular function, exhibit lower blood flow during high-intensity, and maximal knee extension exercise. Thus it appears that in addition to increasing one's risk of cardiovascular disease, lower vascular function is also related to a blunted blood flow response during high-intensity exercise.

Localized Bicep Tissue Bioimpedance Alterations Following Eccentric Exercise in Healthy Young Adults

Objective: The localized bicep tissue bioimpedance was measured from participants who completed an eccentric exercise protocol with one arm and no exercise with the other arm to compare changes that occur as a result of the exercise protocol over a 96h observation period. Methods: The localized bicep bioimpedance, bicep circumference, and self-reports of bicep pain were collected from 6 volunteers at pre, post, 24h, 48h, 72h, and 96h timepoints after completing an eccentric exercise protocol of the elbow flexor muscles. Results: The unexercised bicep showed no statistically significant differences between the pre-exercise and post-exercise measures at any timepoints for all impedance measures and circumference. The exercised bicep showed statistically significant decreases ( $p ) for 10 kHz, 50 kHz, and 100 kHz impedance (resistance and reactance) and increases of bicep circumference at the 72h and 96h post-protocol timepoints, compared to the pre-protocol measurements. The self-reports of pain of the exercised bicep also showed statistically significant increases ( $p ) at the 48h and 72h timepoints compared to the baseline reports. Conclusion: Completion of the eccentric protocol resulted in increases of bicep circumference and decreases in the magnitude of resistance and reactance components of the localized tissue bioimpedance; with maximum changes of swelling and impedance occurring at the same post-protocol timepoints. These changes support that localized tissue bioimpedance is sensitive to the changes that occur as a result of the exercise protocol with the potential to quantify tissues for exercise induced changes. Significance: Localized tissue bioimpedance is sensitive to the changes that occur from eccentric exercise and may be a potential method to non-invasively quantify tissues for changes due to exercise, fatigue, injury, and recovery.

Influence of Sex and Exercise Intensity on Acute Flow‐Mediated Dilation Response to Aerobic Exercise in Healthy Young Adults

Brachial artery flow‐mediated dilation (FMD), a measure of endothelial function, is an independent predictor of future cardiovascular events. Sex and exercise intensity influence the acute FMD response to aerobic exercise in older adults, but in young adults this has not been investigated. Therefore, the purpose of this study was to compare the acute FMD response to a single bout of high‐intensity interval training (HIIT), moderate‐intensity continuous training (MICT) and low‐intensity continuous training (LICT) in young men vs. women. Twenty‐eight healthy young adults (14 men and 14 premenopausal women, 21.2±0.3 vs. 21.5±0.8 years of age, means ± SE, P =0.7) participated in this randomized crossover study. Brachial artery FMD was measured in response to reactive hyperemia following 5‐min forearm occlusion using high resolution ultrasonography. FMD measures were obtained prior to exercise, at the end of a single bout of HIIT (40 min, 4 × 4‐min intervals at 90% peak heart rate (HRpeak), MICT (47 min, 70% HRpeak) and LICT (47 min, 50% HRpeak) on the treadmill and following 60‐min recovery from exercise. The acute FMD response was influenced by exercise intensity but not sex (P=0.006 for exercise intensity × time and P=0.9 for sex × exercise intensity × time), thus the results are presented for men and women combined. FMD was attenuated by 20.7% following the end of HIIT (6.96±0.51 vs. 5.47±0.48%, pre‐ vs. end of exercise; P=0.001) and returned to pre‐exercise levels following 60‐min recovery (P&gt;0.99). However, FMD did not change in response to MICT(7.10±0.53 vs. 6.32±0.57 vs. 7.26±0.37%; P≥0.3) and LICT (7.14±0.41 vs. 7.46±0.56 vs. 7.15±0.43%; P&gt;0.99). In conclusion, exercise intensity, but not sex, significantly impacts the acute FMD response to aerobic exercise in young adults.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.