Impact of moderate-intensity aerobic exercise in combined hypoxic and hot conditions on endothelial function

There is no study that has investigated the impact of exercise in a combined hypoxic and hot environment on endothelial function. Therefore, we tested whether aerobic exercise in a combined hypoxic and hot conditions induces further enhancement of endothelial function. Twelve healthy males cycled at a constant workload (50% of their maximal oxygen uptake under normoxic/thermoneutral conditions) for 30 min in four different environments: exercise under normoxic condition (NOR: fraction of inspiratory oxygen or FiO2 = 20.9%, 20°C), exercise under hypoxic condition (HYP: FiO2 = 14.5%, 20°C), exercise under hot condition (HOT: FiO2 = 20.9%, 30°C), and exercise under combined hypoxia and hot conditions (HH: FiO2 = 14.5%, 30°C). Before, during, and after exercise, cardiovascular variables (e.g., heart rate, blood flow, and shear rate), blood variables, and endothelial function evaluated by flow-mediated dilation (FMD) were assessed. Heart rates were significantly higher throughout the HH trial's experimental period than the other trials (p < 0.05). However, in the HH trial, brachial artery blood flow and shear rate did not differ from those in other trials after exercise. Plasma catecholamines (epinephrine, norepinephrine, and dopamine) elevations in response to exercise were significantly higher in the HH trial than in the other three trials (p < 0.05). No considerable differences were observed in FMD responses among trials before and after the exercise. In conclusion, aerobic exercise in a combined hot and hypoxic environment further activated sympathetic nervous activity but did not considerably enhance blood flow, shear rate, or endothelial function.

Acute Effects of Combining Weight and Elastic Resistance Exercise on Vascular Function in Older Adults

Prior research has suggested that resistance exercise may result in a temporary decrease in vascular function, as measured by flow-mediated dilation (FMD), among untrained young individuals. However, the immediate impact of combined elastic and weight resistance training on older adults remains insufficiently explored. We assessed vascular function before, after, and 30 min after acute exercise under three resistance conditions to evaluate whether a combination of weight and elastic resistance exercises has an acute effect on vascular function in older adults. Fourteen older adults (65.6 ± 2.9 years) executed three sets of 12 repetitions at 65% of one repetition maximum (1 RM) of the bench press (BP) exercise. Testing was performed on three separate days as follows: (1) barbell alone (BA); (2) barbell plus elastic bands (10% of 65% 1 RM) (BE10); and (3) barbell plus elastic bands (20% of 65% 1 RM) (BE20). A two-way (time × condition) repeated measures analysis of variance was employed to assess the time and condition effects on flow-mediated dilation (FMD) and pulse wave velocity (PWV). At 0 min post-exercise, FMD was significantly higher during BE10 than during BA (p < 0.05); however, at 30 min post-exercise, no significant difference (p ≥ 0.05) was observed between the three conditions. In each condition, FMD results did not differ significantly at different times (p ≥ 0.05). For FMD, the main effect of the condition (F[2,26] = 3.86, p = 0.034) and that of the time and condition (F[4,52] = 3.66, p = 0.011) were significant. For PWV, only the difference between the BA and BE10 conditions was significant at 0 min (p < 0.05). PWV increased from baseline in the BA condition (p < 0.05) but not significantly in the BE10 and BE20 conditions (p ≥ 0.05). Therefore, BA, BE10, and BE20 demonstrated various changes in vascular function. Long-term training intervention studies are needed to validate these findings.

Making the case for resistance training in improving vascular function and skeletal muscle capillarization

Through decades of empirical data, it has become evident that resistance training (RT) can improve strength/power and skeletal muscle hypertrophy. Yet, until recently, vascular outcomes have historically been underemphasized in RT studies, which is underscored by several exercise-related reviews supporting the benefits of endurance training on vascular measures. Several lines of evidence suggest large artery diameter and blood flow velocity increase after a single bout of resistance exercise, and these events are mediated by vasoactive substances released from endothelial cells and myofibers (e.g., nitric oxide). Weeks to months of RT can also improve basal limb blood flow and arterial diameter while lowering blood pressure. Although several older investigations suggested RT reduces skeletal muscle capillary density, this is likely due to most of these studies being cross-sectional in nature. Critically, newer evidence from longitudinal studies contradicts these findings, and a growing body of mechanistic rodent and human data suggest skeletal muscle capillarity is related to mechanical overload-induced skeletal muscle hypertrophy. In this review, we will discuss methods used by our laboratories and others to assess large artery size/function and skeletal muscle capillary characteristics. Next, we will discuss data by our groups and others examining large artery and capillary responses to a single bout of resistance exercise and chronic RT paradigms. Finally, we will discuss RT-induced mechanisms associated with acute and chronic vascular outcomes.

Training-induced impairment of endothelial function in track and field female athletes

Professional athletes are often exposed to high training loads that may lead to overfatigue, overreaching and overtraining that might have a detrimental effects on vascular health. We determined the effects of high training stress on endothelial function assessed by the flow-mediated dilation (FMD) and markers of glycocalyx shedding. Vascular examination as well as broad biochemical, hormonal and cardiometabolic evaluation of sprint and middle-distance female runners were performed after 2 months of preparatory training period and compared to age-matched control group of women. Female athletes presented with significantly reduced FMD (p < 0.01) and higher basal serum concentrations of hyaluronan (HA) and syndecan-1 (SDC-1) (p < 0.05 and p < 0.001, respectively), that was accompanied by significantly lower basal serum testosterone (T) and free testosterone (fT) concentrations (p < 0.05) and higher cortisol (C) concentration (p < 0.05). It resulted in significantly lower T/C and fT/C ratios in athletes when compared to controls (p < 0.01). Moreover, fT/C ratio were significantly positively correlated to FMD and negatively to HA concentrations in all studied women. Accordingly, the training load was significantly negatively correlated with T/C, fT/C and FMD and positively with the concentrations of HA and SDC-1. We concluded that young female track and field athletes subjected to physical training developed impairment of endothelial function that was associated with anabolic-catabolic hormone balance disturbances. Given that training-induced impairment of endothelial function may have a detrimental effects on vascular health, endothelial status should be regularly monitored in the time-course of training process to minimalize vascular health-risk in athletes.

Acute impact of aerobic exercise on local cutaneous thermal hyperaemia

Little is known about the acute changes in cutaneous microvascular function that occur in response to exercise, the accumulation of which may provide the basis for beneficial chronic cutaneous vascular adaptations. Therefore, we examined the effects of acute exercise on cutaneous thermal hyperaemia. Twelve healthy, recreationally active participants (11 male, 1 female) performed 30-minute cycling at 50 % (low-intensity exercise, LOW) or 75 % (high-intensity exercise, HIGH) maximum heart rate. Laser Doppler flowmetry (LDF) and rapid local skin heating were used to quantify cutaneous thermal hyperaemia before (PRE), immediately following (IMM) and 1-h (1HR) after exercise. Baseline, axon reflex peak, axon reflex nadir, plateau, maximum skin blood flow responses to rapid local heating (42 °C for 30-min followed by 44 °C for 15-min) at each stage were assessed and indexed as cutaneous vascular conductance [CVC = flux / mean arterial blood pressure (MAP), PU·mm Hg^-1], and expressed as a percentage of maximum (%CVC_max). Exercise increased heart rate (HR), MAP and skin blood flow (all P < 0.001), and to a greater extent during HIGH (all P < 0.001). The axon reflex peak and nadir were increased immediately and 1-h after exercise (all comparisons P < 0.01 vs. PRE), which did not differ between intensities (peak: P = 0.34, axon reflex nadir: P = 0.91). The endothelium-dependent plateau response was slightly elevated after exercise (P = 0.06), with no effect of intensity (P = 0.58) nor any interaction effect (P = 0.55). CONCLUSION: Exercise increases cutaneous microvascular axonal responses to local heating for up to 1-h, suggesting an augmented sensory afferent function post-exercise. Acute exercise may only modestly affect endothelial function in cutaneous microcirculation.

Exercise as an Aging Mimetic: A New Perspective on the Mechanisms Behind Exercise as Preventive Medicine Against Age-Related Chronic Disease

Age-related chronic diseases are among the most common causes of mortality and account for a majority of global disease burden. Preventative lifestyle behaviors, such as regular exercise, play a critical role in attenuating chronic disease burden. However, the exact mechanism behind exercise as a form of preventative medicine remains poorly defined. Interestingly, many of the physiological responses to exercise are comparable to aging. This paper explores an overarching hypothesis that exercise protects against aging/age-related chronic disease because the physiological stress of exercise mimics aging. Acute exercise transiently disrupts cardiovascular, musculoskeletal, and brain function and triggers a substantial inflammatory response in a manner that mimics aging/age-related chronic disease. Data indicate that select acute exercise responses may be similar in magnitude to changes seen with +10-50 years of aging. The initial insult of the age-mimicking effects of exercise induces beneficial adaptations that serve to attenuate disruption to successive "aging" stimuli (i.e., exercise). Ultimately, these exercise-induced adaptations reduce the subsequent physiological stress incurred from aging and protect against age-related chronic disease. To further examine this hypothesis, future work should more intricately describe the physiological signature of different types/intensities of acute exercise in order to better predict the subsequent adaptation and chronic disease prevention with exercise training in healthy and at-risk populations.

Slow-Speed Low-Intensity but Not Normal-Speed High-Intensity Resistance Exercise Maintains Endothelial Function

Purpose: High-intensity resistance exercise two or three times a week has been considered optimal for muscle hypertrophy, although it can remarkably elevate blood pressure (BP). In contrast, slow-speed resistance exercise with low intensity and tonic force generation (slow-low) can induce muscle hypertrophy without elevating BP. However, it is unclear how endothelial function changes after slow-low. Therefore, this study examined whether slow-low would maintain brachial artery endothelial function in comparison with normal-speed with high intensity resistance exercise (normal-high) and normal-speed with low-intensity resistance exercise (normal-low). Methods: Eleven healthy young men performed leg-extensions with slow-low (3 sets of 8 repetitions at 50% of 1RM), normal-high (3 sets of 8 repetitions at 80% of 1RM), and normal-low (3 sets of 8 repetitions at 50% of 1RM). Flow-mediated dilation (FMD) in the brachial artery was evaluated at pre-exercise and at 10, 30, and 60 min after exercise. Result: The results showed that normal-high caused significant impairment of FMD at 30 (3.7 ± 2.7%) and 60 (3.7 ± 2.8%) min after exercise (P < .05). In contrast, slow-low and normal-low showed no significant difference from baseline. FMD was significantly lower in normal-high compared with slow-low and normal-low at 30 and 60 min after exercise (P < .05). Additionally, systolic BP was significantly higher during normal-high compared with slow-low and normal-low (P < .05). Conclusion: We concluded that slow-low did not impair brachial artery FMD concomitant with lower systolic BP, and may therefore be a useful mode of exercise training to improve muscle hypertrophy without provoking transient endothelial dysfunction.

Low-to-Moderate-Intensity Resistance Exercise Is More Effective than High-Intensity at Improving Endothelial Function in Adults: A Systematic Review and Meta-Analysis

Aerobic exercise has been confirmed to improve endothelial function (EF). However, the effect of resistance exercise (RE) on EF remains controversial. We conducted this systematic review and meta-analysis on randomized controlled trials (RCTs) to determine the effect of RE and its intensities on EF. We searched Web of Science, PubMed/MEDLINE, Scopus, and Wiley Online Library, and included 15 articles (17 trials) for the synthesis. Overall, RE intervention significantly improved flow-mediated dilatation (FMD) in brachial artery (SMD = 0.76; 95% CI: 0.47, 1.05; p < 0.00001), which represents improved EF. Meta-regression showed that the RE intensity was correlated with changes in FMD (Coef. = −0.274, T = −2.18, p = 0.045). We found both intensities of RE improved FMD, but the effect size for the low- to moderate-intensity (30–70%1RM) was bigger (SMD = 1.02; 95% CI: 0.60, 1.43; p < 0.0001) than for the high-intensity (≥70%1RM; SMD = 0.48; 95% CI: 0.21, 0.74; p = 0.005). We further noticed that RE had a beneficial effect (SMD = 0.61; 95% CI: 0.13, 1.09; p = 0.01) on the brachial artery baseline diameter at rest (BAD_rest), and the age variable was correlated with the changes in BAD_rest after RE (Coef. = −0.032, T = −2.33, p = 0.038). Young individuals (<40 years) presented with a bigger effect size for BAD_rest (SMD = 1.23; 95% CI: 0.30, 2.15; p = 0.009), while middle-aged to elderly (≥40 years) were not responsive to RE (SMD = 0.07; 95% CI: −0.28, 0.42; p = 0.70). Based on our findings, we conclude that RE intervention can improve the EF, and low- to moderate-intensity is more effective than high-intensity.

Acute flywheel exercise does not impair the brachial artery vasodilation in healthy men of varying aerobic fitness

BACKGROUND

The cardiovascular response to variable load exercise on a flywheel ergometer is still unknown.

OBJECTIVE

This study examined the effects of flywheel exercise on cardiovascular response and brachial artery vasodilation capacity in healthy, active men.

METHODS

In this cross-sectional study, nineteen men (20-57 years old) completed three laboratory visits, including a ramp exercise test to determine their maximal oxygen uptake JOURNAL/blpmo/04.03/00126097-202106000-00008/inline-graphic1/v/2021-04-27T091817Z/r/image-tiff max, and exercise intervention on a flywheel ergometer set at 0.075 kg·m2 moment of inertia. After the ramp test cessation, all participants were allocated into aerobically untrained (n = 10) and trained (n = 9) groups. Throughout the flywheel exercise, cardiovascular demands were continuously monitored via Finapres, while a pre/postflow-mediated dilation (FMD) assessment was performed using ultrasound imaging.

RESULTS

There were no differences observed between the groups in their anthropometrics, age or resting brachial artery diameter, while the JOURNAL/blpmo/04.03/00126097-202106000-00008/inline-graphic2/v/2021-04-27T091817Z/r/image-tiff max was ~15% higher (P = 0.001) in trained compared to aerobically untrained group. The cardiovascular response to the flywheel exercise was similar between the groups, with peak mean arterial pressure and heart rate readings reaching ~160 mmHg and ~140 bpm, respectively. The flywheel exercise did not impair the FMD (%) response, which was comparable between the groups (P = 0.256). When these data were pooled, the regression analysis showed an inverse relationship among FMD (%), age (β = -0.936, P = 0.001) and JOURNAL/blpmo/04.03/00126097-202106000-00008/inline-graphic3/v/2021-04-27T091817Z/r/image-tiffmax. (β = -0.359, P = 0.045).

CONCLUSION

Although aerobic fitness alone does not directly explain the FMD response to flywheel exercise, aerobically untrained individuals, as they get older, tend to have lower brachial artery FMD.

Exercise modality, but not exercise training, alters the acute effect of exercise on endothelial function in healthy men

We used a within-subject crossover design to examine the impact of exercise modality, i.e., resistance (RT) and endurance (END), on the acute impact of exercise on endothelial function. Then, we examined whether a 4-wk period of chronic exercise training altered the acute exercise-induced change in endothelial function in healthy individuals. Thirty-four healthy, young men (21 ± 2 yr) reported to our laboratory and completed assessment of endothelial function [using the brachial artery flow-mediated dilation test (FMD)] before and immediately after a single bout of RT (leg-extension) or END (cycling). Subsequently, participants completed a 4-wk period of training (12 sessions), followed by evaluation of the FMD before and after a single bout of exercise. Following a 3-wk washout, participants repeated these experiments with the different exercise modality (in a balanced crossover design). An exercise × modality interaction effect was found (P < 0.001). Post hoc pairwise analyses revealed a decrease in FMD after END (P < 0.001) but not after RT (P = 0.06). Four weeks of exercise training improved resting FMD after END and RT (P = 0.04) but did not alter the acute effect of exercise on FMD (exercise × modality × training effect: P = 0.63), an effect independent of the modality of exercise (exercise × training interaction: P = 0.46 and P = 0.11 in RT and END, respectively). These distinct changes in FMD following acute exercise may relate to the different prolonged physiological responses induced by endurance versus resistance exercise. Specifically, endurance exercise, but not resistance exercise, causes a decrease in brachial artery endothelial function, which was unaffected by 4 wk of chronic exercise training.NEW & NOTEWORTHY We found that resistance and endurance exercise modalities lead to different endothelial function responses after a single bout of exercise. Endothelial function increased after an acute bout of resistance exercise, whereas it decreased after an acute bout of endurance exercise. Four weeks of chronic exercise training did not affect the acute endothelial function response.

Effects of Traditional and Vascular Restricted Strength Training Program With Equalized Volume on Isometric and Dynamic Strength, Muscle Thickness, Electromyographic Activity, and Endothelial Function Adaptations in Young Adults

Ramis, TR, Muller, CHdL, Boeno, FP, Teixeira, BC, Rech, A, Pompermayer, MG, Medeiros, NdS, Oliveira, ÁRd, Pinto, RS, and Ribeiro, JL. Effects of traditional and vascular restricted strength training program with equalized volume on isometric and dynamic strength, muscle thickness, electromyographic activity, and endothelial function adaptations in young adults. J Strength Cond Res 34(3): 689-698, 2020-The purpose of the study was to evaluate and compare the acute and chronic effects of partial vascular occlusion training in young, physically active adults. Neuromuscular, morphological, and endothelial function responses were compared between high-intensity resistance training (HI-RT) and low-intensity resistance training with partial vascular occlusion (LI-BFR), despite the same training volume. The 28 subjects (age, 23.96 ± 2.67 years) were randomly assigned into 2 groups: LI-BFR (n = 15) and HI-RT (n = 13). Both groups performed unilateral exercise of elbow flexion (EF) and knee extension (KE) 3 times per week for 8 weeks. This study was approved by the ethics committee. Flow-mediated dilation showed a significant difference in baseline and post-training in the LI-BFR group (4.44 ± 0.51 vs. 6.35 ± 2.08 mm, respectively). For nitrite/nitrate concentrations only, there was a significant difference when comparing pre- and post-acute exercise in both groups. The torque and rep. Sixty percent 1 repetition maximum had improvements in both groups. There were differences between groups only in isometric delta EF and isokinetic delta KE (EF 3.42 ± 5.09 and 9.61 ± 7.52 N·m; KE 12.78 ± 25.61 and 42.69 ± 35.68 N·m; LI-BFR and HI-RT groups, respectively). There was a significant increase of muscle thickness in both groups. An increase of both isokinetic and isometric electromyography (EMG) of biceps of the HI-RT group was observed. The same was observed for the LI-BFR group regarding isokinetic and isometric EMG of vastus lateralis. Thus, in addition to strength and hypertrophy gains, this study also shows benefits related to vascular function. For practical applications, this study demonstrates a clinical importance of LI-BFR training as an alternative methodology.

Maintenance of endothelial function following acute resistance exercise in females is associated with a tempered blood pressure response

Acute resistance exercise-induced hypertensive stimulus impairs endothelial function in males. Because prior work indicates that female subjects have a tempered blood pressure response to acute resistance exercise, we hypothesized that, compared with males, females would better maintain endothelial function following resistance exercise and that this preservation would be associated with a lower hypertensive stimulus. Twenty-nine young healthy males (n = 16) and females (n = 13) participated in this study. All subjects performed a session of resistance exercise (leg extension) at the same relative workload [65% of one repetition maximum (1RM)]. The blood pressure response to exercise was characterized, and brachial artery flow-mediated dilation (FMD) was measured before and after. Males performed a second experimental trial in which the blood pressure response to resistance exercise was matched to that of females. This was accomplished by reducing the workload (~25% of 1RM). When resistance exercise was performed at the same relative workload, the systolic blood pressure was greater in males compared with females. Congruently, resistance exercise caused a significant impairment in FMD in males but not in females (P < 0.001). When the exercise workload was reduced in males, they no longer displayed an impairment in FMD following resistance exercise and, as such, the sex difference was abolished (P > 0.05). The present study reveals that acute resistance exercise transiently impairs endothelial function in young, healthy males but not in age-matched females. Notably, the maintenance of endothelial function in females is associated with a lower blood pressure response during resistance exercise.NEW & NOTEWORTHY The present data demonstrate for the first time that acute resistance exercise impairs endothelial function in young, healthy male but not female subjects. In addition, we show that the preservation of endothelial function in females is associated with a mitigated blood pressure response during resistance exercise. Accordingly, this work portrays a sexual dimorphism in the barostress response, and ensuing vascular effects, to resistance exercise.

Flow-Mediated Dilation in Healthy Young Individuals Is Impaired after a Single Resistance Exercise Session

The current pool of data investigating the effects of a single resistance exercise session on endothelial function is divergent and inconclusive. Therefore, the purpose of the present study was to evaluate the effect of a single resistance exercise session on flow-mediated dilation (FMD) in trained individuals. Eleven healthy, young, recreationally resistance-trained individuals participated in the study. After determining the resistance exercise workload, the participants performed three sets of 10–12 repetition of leg press and leg extension exercises. By using ultrasound equipment, brachial artery FMD was assessed before (PRE) and 30 min after (POST) the resistance exercise protocol or resting (control) to evaluate endothelial function. A significant reduction in FMD response (PRE: 5.73% ± 1.21% vs. POST: 4.03% ± 1.94%, p < 0.01) after resistance exercise was observed, accompanied by a large effect size (d = 1.05). No significant difference was observed in FMD in the control condition (PRE: 5.82% ± 1.19% vs. POST: 5.66% ± 1.24%, p = 0.704). Additionally, no significant difference in baseline brachial artery diameter between resistance exercise (PRE: 3.30 ± 0.32 vs. POST: 3.40 ± 0.34 mm, p = 0.494) and resting (PRE: 3.64 ± 0.41 vs. POST: 3.67 ± 0.62 mm, p = 0.825) was observed. Our findings showed that a single resistance exercise session induced a reduction in FMD in resistance-trained individuals.

Endothelial function in response to exercise in the cold in patients with coronary artery disease

BACKGROUND

Regular long-term physical exercise has favourable effects on endothelial function in patients with coronary artery disease (CAD). However, the effects of an acute exercise bout in the cold on endothelial function are not known.

METHODS

At first, the effects of moderate-intensity aerobic lower-body exercise were assessed in CAD patients (n = 16) in a neutral [+22°C] and cold [-15°C] environment. Secondly, responses to static and dynamic upper-body exercise in a neutral [+22°C] and cold [-15°C] environment were investigated in CAD patients (n = 15). All experiments were performed in a random order. Endothelial function was measured by flow-mediated dilation (FMD) of the brachial artery in response to reactive hyperaemia, before and after the exposures in a neutral environment.

RESULTS

No significant temperature*exercise*condition (pre-post) interaction was observed in FMD% when comparing rest versus aerobic exercise or static versus dynamic upper-body exercise. Relative reactive hyperaemia during FMD protocol, measured by changes in shear rate, was elevated after rest compared to aerobic exercise (p = .001) and after static compared to dynamic upper-body exercise (p < .001). However, no significant temperature*exercise*condition interaction was observed when FMD% was normalized for shear rate.

CONCLUSIONS

Endothelial function to an acute bout of exercise among CAD patients was not modified by the environmental temperature where the exercise was performed. The present findings argue against the hypothesis that exercise in cold environmental conditions impairs endothelial function in patients with CAD.

Effects of resveratrol or estradiol on postexercise endothelial function in estrogen-deficient postmenopausal women

Regular exercise enhances endothelial function in older men, but not consistently in estrogen-deficient postmenopausal women. Estradiol treatment improves basal endothelial function and restores improvements in endothelial function (flow-mediated dilation, FMD) to aerobic exercise training in postmenopausal women; however, estradiol treatment is controversial. Resveratrol, an estrogen receptor ligand, enhances exercise training effects on cardiovascular function and nitric oxide (NO) release in animal models, but impairs exercise training effects in men. We conducted a randomized cross-over, double-blinded, placebo-controlled pilot study to determine whether acute (single dose) resveratrol (250-mg tablet) or estradiol (0.05 mg/day transdermal patch) treatment enhances FMD at rest and after a single bout of moderate-intensity aerobic exercise in healthy estrogen-deficient postmenopausal women (n = 15, 58.1 ± 3.2 yr). FMD was measured before and after (30, 60, and 120 min) a 40-min bout of moderate-intensity treadmill exercise (60-75% peak heart rate) under the respective conditions (separated by 1-2 wk). FMD was higher (P < 0.05) before exercise and at all post-exercise time points in the resveratrol and estradiol conditions compared to placebo. FMD was increased from baseline by 120 min postexercise in the estradiol condition (P < 0.001), but not resveratrol or PL conditions. Consistent with our previous findings, estradiol also enhances endothelial function in response to acute endurance exercise. Although resveratrol improved basal FMD, there was no apparent enhancement of FMD to acute exercise and, therefore, may not act as an estradiol mimetic.NEW & NOTEWORTHY The benefits of endurance exercise training on endothelial function are diminished in estrogen-deficient postmenopausal women, but estradiol treatment appears to restore improvements in endothelial function in this group. We show that basal endothelial function is enhanced with both acute estradiol and resveratrol treatments in estrogen-deficient postmenopausal women, but endothelial function is only enhanced following acute endurance exercise with estradiol treatment.

Post-exercise Response of Arterial Parameters for Arterial Health Assessment Using a Microfluidic Tactile Sensor and Vibration-Model-Based Analysis: A Proof-of-Concept Study

OBJECTIVE

Arterial stiffness and endothelial function are two established surrogate markers of subclinical atherosclerosis and are quantified by three arterial parameters: elasticity, viscosity and radius of the arterial wall. Yet, the current methods for their assessment are unsuitable for routine use. Post-exercise response of the cardiovascular (CV) system serves as a more sensitive detection of subclinical arterial abnormalities that are not apparent at-rest. The objective of this study is to propose a novel method that can measure post-exercise response of arterial parameters and is also suitable for routine use.

APPROACH

A microfluidic tactile sensor with a location-insensitive configuration was used for arterial pulse signal measurements on six asymptomatic male subjects, offering measurement reliability, ease use by a layperson, and affordability. By treating the arterial pulse signal as a vibration signal of the arterial wall, vibration-model-based analysis of only one measured pulse signal with no calibration was conducted for simultaneous estimation of three arterial parameters. Exercise-intensity-normalized percent changes in arterial parameters were utilized to remove the influence of variation in exercise intensity on post-exercise response, and then their measured values were compared for difference in post-exercise response between the subjects.

MAIN RESULTS

One subject who was obese, on subject who had insomnia, and the oldest subject in the study demonstrated differences in post-exercise response at the radial artery (RA), as compared with the three subjects free of those three factors. Despite a lack of statistical significance, the observed difference at the RA between subjects was supported by (i) their consistency with the related findings in the literature, and (ii) their consistency with the measured values at the carotid artery (CA) and superficial temporal artery (STA) and the anatomical difference between the three arteries.

SIGNIFICANCE

The proposed method has the potential of offering an affordable and convenient diagnosis tool for routine arterial health assessment.

The Impact of Different Exercise Intensities on Vasodilation and Shear Rate Patterns in Children

PURPOSE

The effect of exercise intensity on vasodilator function is poorly understood in children. The authors compared the acute effect of high-intensity interval exercise (HIIE) with moderate-intensity steady-state exercise (MISS) on postexercise vasodilation and shear patterns in 7- to 12- year-old children.

METHODS

Superficial femoral artery diameter, shear rates, and flow-mediated dilation were measured pre, immediately following (post), and 1 hour after (post60) HIIE (six 1-min sprints at 90% peak power [Wmax], with 1-min recovery) and MISS (15 min at 44% Wmax).

RESULTS

Baseline superficial femoral artery diameter increased similarly following both HIIE (pre 4.23 [0.41] mm, post 4.73 [0.56] mm) and MISS (pre 4.28 [0.56] mm, post 4.59 [0.64] mm), returning to preexercise values post60. Blood flow and antegrade shear rate were increased post HIIE and MISS, but to a greater extent, post HIIE (P < .05). Retrograde shear rate was attenuated post both exercise conditions and remained post60 (P < .001). There was a decline in flow-mediated dilation postexercise (HIIE Δ -2.9%; MISS Δ -2.4%), which was no longer apparent when corrected for baseline diameter.

CONCLUSION

Acute bouts of external work-matched HIIE or MISS exert a similar impact on shear-mediated conduit artery vasodilation and flow-mediated dilation in children, and this is reversed 1 hour after exercise.

Effects of a Single Session of High- and Moderate-Intensity Resistance Exercise on Endothelial Function of Middle-Aged Sedentary Men

Regular resistance exercise is associated with metabolic, neuromuscular and cardiovascular adaptations which improve quality of life and health. However, sedentary subjects have shown acute impairments in endothelial function after high-intensity resistance exercise. The aim of this study was to evaluate endothelial function in sedentary middle-aged men after a single session of resistance exercise at different intensities. Eleven sedentary middle-aged men (40.1 ± 3.9 years; 27.3 ± 1.4 kg/m²) underwent three different conditions of assessment: (1) single knee extension exercise at moderate intensity (MI) [4 sets of 12 repetitions at 50% of one repetition maximum (1RM) for each leg], (2) single knee extension exercise at high intensity (HI) (4 sets of 8 repetitions at 80% of 1RM for each leg), (3) resting for the control condition (CON). Flow-mediated dilation (FMD) was assessed before, 30 and 60 min after exercise. Plasma concentrations of endothelin-1 (ET-1), nitrites and nitrates (NO_x) and thiobarbituric acid reactive substances (TBARS) were measured before, immediately after and 60 min after exercise. Blood pressure (BP) was measured prior to the experimental protocols, and in the following times: immediately following, and 2, 5, 10, 15, 30, and 60 min after exertion. There was a significant improvement in FMD 30 min after MI condition (12.5 ± 4.10 vs. 17.2 ± 3.9%; p = 0.016). NO_x levels were significantly higher immediately after MI (6.8 ± 3.3 vs. 12.6 ± 4.2 μM; p = 0.007) and there was a significant increase in the concentration of ET-1 immediately after HI (20.02 ± 2.2 vs. 25.4 ± 2.1 pg/mL; p = 0.004). However, there was no significant difference for BP (MI vs. HI) and TBARS among the experimental conditions. Resistance exercise performed at moderate intensity improved vasodilatation via increases on NOx levels and FMD in sedentary middle-aged men.

High-intensity resistance exercise with low repetitions maintains endothelial function

Resistance exercise impairs endothelial function, and this impairment is thought to be mediated by sustained elevation in blood pressure. Herein, we tested the hypothesis that resistance exercise-induced endothelial dysfunction would be prevented by high-intensity resistance exercise with low repetitions. This type of resistance exercise is known to induce temporal elevation in blood pressure due to low repetitions and a long resting period between sets. Thirteen young healthy subjects completed three randomized experimental trials as follows: 1) moderate-intensity exercise with moderate repetitions (moderate-moderate trial), 2) low-intensity exercise with high repetitions (low-high trial), and 3) high-intensity exercise with low repetitions (high-low trial). After baseline brachial artery flow-mediated dilation (FMD) and blood pressure measurements, subjects performed resistance exercise according to the different types of trials. Thereafter, brachial artery FMD and blood pressure measurements were repeated 10, 30, and 60 min after the exercise. Exercise-induced increases in blood flow and shear rate were significantly lower in the high-low trial than in the other two trials ( P < 0.05). Although systolic blood pressures were significantly elevated after exercise in all trials ( P < 0.05), the magnitudes of rise in blood pressure increase were significantly lower in the high-low trial than in the moderate-moderate and low-high trials ( P < 0.05). Moderate-moderate and low-high trials caused a significant impairment in brachial artery FMD ( P < 0.05), which could be prevented through high-intensity resistance exercise with low repetitions (  > 0.05). In conclusion, endothelial function was maintained by conducting high-intensity resistance exercise with low repetitions. NEW & NOTEWORTHY Data from the present study reveal that high-intensity resistance exercise with low repetitions can maintain endothelial function. Thus, this study provides the first evidence that the detrimental vascular effects of resistance exercise are preventable when resistance exercise is performed in high intensity with low repetitions. Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/type-of-resistance-exercise-and-endothelial-function/ (Japanese version: https://ajpheart.podbean.com/e/japanese-language-podcast-type-of-resistance-exercise-and-endothelial-function/ ).

Acute exhaustive rowing exercise reduces skin microvascular dilator function in young adult rowing athletes

PURPOSE

The effect of acute exhaustive exercise session on skin microvascular reactivity was assessed in professional rowers and sedentary subjects. A potential involvement of altered hemodynamic parameters and/or oxidative stress level in the regulation of skin microvascular blood flow by acute exercise were determined.

METHODS

Anthropometric, biochemical, and hemodynamic parameters were measured in 18 young healthy sedentary men and 20 professional rowers who underwent a single acute exercise session. Post-occlusive reactive hyperemia (PORH), endothelium-dependent acetylcholine (ACh), and endothelium-independent sodium nitroprusside (SNP) microvascular responses were assessed by laser Doppler flowmetry in skin microcirculation before and after acute exercise. Serum lipid peroxidation products and plasma antioxidant capacity were measured using spectrophotometry.

RESULTS

At baseline, rowers had significantly lower diastolic blood pressure (DBP) and heart rate (HR), and higher stroke volume (SV), PORH, and endothelium-dependent vasodilation than sedentary. Acute exercise caused a significant increase in systolic blood pressure, DBP, HR, and SV and a decrease in total peripheral resistance in both groups. Acute exercise induced a significant impairment in PORH and ACh-induced response in rowers, but not in sedentary, whereas the SNP-induced vasodilation was not affected by acute exercise in any group. Antioxidant capacity significantly increased only in sedentary after acute exercise.

CONCLUSION

Single acute exercise session impaired microvascular reactivity and endothelial function in rowers but not in sedentary, possibly due to (1) more rowing grades and higher exercise intensity achieved by rowers; (2) a higher increase in arterial pressure in rowers than in sedentary men; and (3) a lower antioxidant capacity in rowers.

Do acute effects of exercise on vascular function predict adaptation to training?

Purpose

No previous study has explored the importance of exercise-induced changes in vascular function to prolonged adaptations. Therefore, the purpose was to explore the within-subject relationship between the acute post-exercise change in brachial artery endothelial function (flow-mediated dilation, FMD) and the change in resting FMD after a 2-week exercise training in healthy volunteers.

Methods

Twenty one healthy, young men (24 ± 5 years) underwent assessment of brachial artery FMD using high-resolution ultrasound before and after 30-min of moderate-intensity cycle exercise (80% maximal heart rate). Subsequently, subjects performed five 30-min cycle exercise bouts at 80% maximal heart rate across a 2-week period, followed by repeat assessment of resting brachial FMD post-training.

Results

Correcting for changes in diameter and shear, FMD did not change after the initial exercise bout (P = 0.26). However, a significant correlation was found between post-exercise changes in FMD and adaptation in resting FMD after training (r = 0.634, P = 0.002), where an acute decrease in post-exercise FMD resulted in a decrease in baseline FMD after 2 weeks and vice versa. We also found a positive correlation between antegrade shear rate during exercise and change in FMD% after acute exercise and after exercise training (r = 0.529 and 0.475, both P < 0.05).

Conclusion

Our findings suggest that acute post-exercise changes in vascular function are related to changes in resting FMD after a 2-week endurance exercise training period in healthy men, an effect that may be related to exercise-induced increases in antegrade shear rate. This provides further insight into the relevance of acute changes in shear and FMD for subsequent adaptation.

Hypertension during Weight Lifting Reduces Flow-Mediated Dilation in Nonathletes

PURPOSE

The purpose of this study was to determine whether increased intraluminal pressure is the damaging factor that reduces flow-mediated dilation (FMD) in young, healthy subjects after resistance exercise to maximal exertion.

HYPOTHESIS

Attenuating the rise in brachial artery pressure during weight lifting by placing a blood pressure cuff on the upper arm prevents postexercise impairment of brachial artery FMD in sedentary individuals.

METHODS

Nine sedentary individuals who exercise once a week or less and six exercise-trained individuals who exercise three times a week or more performed leg press exercise to maximal exertion on two separate occasions. During one visit, a blood pressure cuff, proximal to the site of brachial artery measurement, was inflated to 100 mm Hg to protect the distal vasculature from the rise in intraluminal pressure, which occurs during resistance exercise. Brachial artery FMD was determined using ultrasonography before and 30 min after weight lifting.

RESULTS

Without the protective cuff, brachial artery FMD in sedentary individuals was reduced after weight lifting (9.0% ± 1.2% prelift vs 6.6% ± 0.8% postlift; P = 0.005), whereas in exercise-trained individuals, FMD was unchanged (7.4% ± 0.7% prelift vs 8.0% ± 0.9% postlift; P = 0.543). With the protective cuff, FMD no longer decreased but rather increased in sedentary individuals (8.7% ± 1.2% prelift vs 10.5% ± 1.0% postlift, P = 0.025). An increase in FMD was also seen in exercise-trained subjects when the cuff was present (6.6% ± 0.7% prelift vs 10.9% ± 1.5% postlift, P < 0.001).

CONCLUSION

Protecting the brachial artery from exercise-induced hypertension enhances FMD in sedentary and exercise-trained individuals. These results indicate that increased intraluminal pressure in the artery contributes to the reduced FMD after heavy resistance exercise in sedentary individuals.

The effect of an acute bout of resistance exercise on carotid artery strain and strain rate

Arterial wall mechanics likely play an integral role in arterial responses to acute physiological stress. Therefore, this study aimed to determine the impact of low and moderate intensity double‐leg press exercise on common carotid artery (CCA) wall mechanics using 2D vascular strain imaging. Short‐axis CCA ultrasound images were collected in 15 healthy men (age: 21 ± 3 years; stature: 176.5 ± 6.2 cm; body mass; 80.6 ± 15.3 kg) before, during, and immediately after short‐duration isometric double‐leg press exercise at 30% and 60% of participants' one‐repetition maximum (1RM: 317 ± 72 kg). Images were analyzed for peak circumferential strain (PCS), peak systolic and diastolic strain rate (S‐SR and D‐SR), and arterial diameter. Heart rate (HR), systolic and diastolic blood pressure (SBP and DBP) were simultaneously assessed and arterial stiffness indices were calculated post hoc. A two‐way repeated measures ANOVA revealed that during isometric contraction, PCS and S‐SR decreased significantly (P < 0.01) before increasing significantly above resting levels post exercise (P < 0.05 and P < 0.01, respectively). Conversely, D‐SR was unaltered throughout the protocol (P = 0.25). No significant differences were observed between the 30% and 60% 1RM trials. Multiple regression analysis highlighted that HR, BP, and arterial diameter did not fully explain the total variance in PCS, S‐SR, and D‐SR. Acute double‐leg press exercise is therefore associated with similar transient changes in CCA wall mechanics at low and moderate intensities. CCA wall mechanics likely provide additional insight into localized intrinsic vascular wall properties beyond current measures of arterial stiffness.

Cardiorespiratory fitness modulates the acute flow-mediated dilation response following high-intensity but not moderate-intensity exercise in elderly men

Impaired endothelial function is observed with aging and in those with low cardiorespiratory fitness (V̇o2peak). Improvements in endothelial function with exercise training are somewhat dependent on the intensity of exercise. While the acute stimulus for this improvement is not completely understood, it may, in part, be due to the flow-mediated dilation (FMD) response to acute exercise. We examined the hypothesis that exercise intensity alters the brachial (systemic) FMD response in elderly men and is modulated by V̇o2peak. Forty-seven elderly men were stratified into lower (V̇o2peak = 24.3 ± 2.9 ml·kg−1·min−1; n = 27) and higher fit groups (V̇o2peak = 35.4 ± 5.5 ml·kg−1·min−1; n = 20) after a test of cycling peak power output (PPO). In randomized order, participants undertook moderate-intensity continuous exercise (MICE; 40% PPO) or high-intensity interval cycling exercise (HIIE; 70% PPO) or no-exercise control. Brachial FMD was assessed at rest and 10 and 60 min after exercise. FMD increased after MICE in both groups {increase of 0.86% [95% confidence interval (CI), 0.17–1.56], P = 0.01} and normalized after 60 min. In the lower fit group, FMD was reduced after HIIE [reduction of 0.85% (95% CI, 0.12–1.58), P = 0.02] and remained decreased at 60 min. In the higher fit group, FMD was unchanged immediately after HIIE and increased after 60 min [increase of 1.52% (95% CI, 0.41–2.62), P < 0.01, which was correlated with V̇o2peak, r = 0.41; P < 0.01]. In the no-exercise control, FMD was reduced in both groups after 60 min ( P = 0.05). Exercise intensity alters the acute FMD response in elderly men and V̇o2peak modulates the FMD response following HIIE but not MICE. The sustained decrease in FMD in the lower fit group following HIIE may represent a signal for vascular adaptation or endothelial fatigue.

NEW & NOTEWORTHY This study is the first to show that moderate-intensity continuous cycling exercise increased flow-mediated dilation (FMD) transiently before normalization of FMD after 1 h, irrespective of cardiorespiratory fitness level in elderly men. Interestingly, we show increased FMD after high-intensity cycling exercise in higher fit men, with a sustained reduction in FMD in lower fit men. The prolonged reduction in FMD after high-intensity cycling exercise may be associated with future vascular adaptation but may also reflect a period of increased cardiovascular risk in lower fit elderly men.

Resistance-based interval exercise acutely improves endothelial function in type 2 diabetes

Different modes of exercise, disease, and training status can modify endothelial shear stress and result in distinct effects on endothelial function. To date, no study has examined the influence of type 2 diabetes (T2D) and training status on the acute endothelial response to different modes of interval exercise (INT). We examined the effect of a single session of resistance- and cardio-based INT compared with a time-matched control on endothelial function in 12 age-matched T2D participants, 12 untrained, and 11 trained adults (aged 56 ± 7 yr). Flow-mediated dilation (%FMD) of the brachial artery was assessed at baseline and immediately, 1, and 2 h after an acute bout of cardio interval (C-INT), resistance interval (R-INT), and seated control (CTL); these interventions were randomized and separated by >2 days. C-INT involved seven 1-min cycling intervals at 85% of peak power with 1-min recovery between. R-INT involved the same pattern of seven 1-min intervals using leg resistance exercises. Endothelial function (%FMD) was improved after R-INT in all groups (Condition × Time interaction, P < 0.01), an effect that was most robust in T2D where %FMD was higher immediately (+4.0 ± 2.8%), 1 h (+2.5 ± 2.5%), and 2 h (+1.9 ± 1.9%) after R-INT compared with CTL (P < 0.01 for all). C-INT improved %FMD in T2D at 1-h postexercise (+1.6 ± 2.2%, P = 0.03) compared with CTL. In conclusion, R-INT acutely improves endothelial function throughout the 2-h postexercise period in T2D patients. The long-term impact of resistance exercise performed in an interval pattern is warranted.

Impact of handgrip exercise intensity on brachial artery flow-mediated dilation

PURPOSE

Previous studies that have examined the impact of exercise intensity on conduit artery endothelial function have involved large muscle group exercise which induces local and systemic effects. The aim of this study was to examine flow-mediated dilation (FMD) before and after incremental intensities of handgrip exercise (HE), to assess the role of local factors such as blood flow and shear rate on post-exercise brachial artery function.

METHODS

Eleven healthy men attended the laboratory on three occasions. Subjects undertook 30 min of handgrip exercise at three intensities (5, 10 or 15 % MVC). Brachial artery FMD, shear and blood flow patterns were examined before, immediately after and 60 min post exercise.

RESULTS

Handgrip exercise increased mean and antegrade shear rate (SR) and blood flow (BF) and reduced retrograde SR and BF (all P < 0.01). Exercise intensity was associated with a dose-dependent increase in both mean and antegrade BF and SR (interaction, P < 0.01). Post-hoc tests revealed that, whilst handgrip exercise did not immediately induce post-exercise changes, FMD was significantly higher 60 min post-exercise following the highest exercise intensity (5.9 ± 2.8-10.4 ± 5.8 %, P = 0.01).

CONCLUSIONS

Handgrip exercise leads to intensity-and time-dependent changes in conduit artery function, possibly mediated by local increases in shear, with improvement in function evident at 1 h post-exercise when performed at a higher intensity.

Effects of acute exercise on flow-mediated dilatation in healthy humans

Although the effects of exercise training on vascular function have been well studied, less is known about the effects of acute exercise bouts. This synthesis summarizes and integrates knowledge derived from papers relating acute impacts of exercise on artery function, specifically endothelial function assessed by flow-mediated dilatation (FMD). We propose that an immediate decrease in FMD ("nadir") occurs soon after exercise cessation and that this is followed by a (supra)normalization response. The magnitude of the nadir and (supra)normalization and duration of this biphasic pattern of response appears to be influenced by numerous factors, including the nature of the exercise stimulus (e.g., type, duration, intensity), the subject population (e.g., trained vs. untrained), and various methodological factors. The impact of these factors on the biphasic pattern are most likely mediated through stimuli that underpin altered FMD postexercise, including shear and oxidative stress, changes in arterial diameter, and antioxidant status. We propose that a combination of these stimuli act synergistically to balance the vasomotor responses postexercise. Finally, we discuss the potential (clinical) relevance of the biphasic response after acute exercise, as the immediate nadir may represent an essential response for subsequent training-induced adaptations but may also represent a transient period of increased cardiovascular risk leading to the "exercise paradox."