Aerobic exercise intensity and time of stressor administration influence cardiovascular responses to psychological stress

The effects of acute exercise on stress reactivity assessed via a multidimensional approach: a systematic review

Psychological stress is associated with numerous deleterious health effects. Accumulating evidence suggests acute exercise reduces stress reactivity. As stressors activate a wide array of psychological and physiological systems it is imperative stress responses are examined through a multidimensional lens. Moreover, it seems prudent to consider whether stress responses are influenced by exercise intervention characteristics such as modality, duration, intensity, timing, as well as participant fitness/physical activity levels. The current review therefore examined the role of acute exercise on stress reactivity through a multidimensional approach, as well as whether exercise intervention characteristics and participant fitness/physical activity levels may moderate these effects. Stress reactivity was assessed via heart rate, blood pressure, cortisol, catecholamines, and self-report. A systematic search following PRISMA guidelines of five databases was updated in November 2022. Reviewed studies met the following criteria: English language, participants aged ≥ 18, use of acute exercise, use of a validated stress-inducing task, and assessment(s) of stress reactivity. Thirty-one studies (1386 participants) were included. Acute exercise resulted in reliable reductions to blood pressure and cortisol. Acute exercise yielded mostly negligible effects on heart rate reactivity and negligible effects on self-report measures. As for exercise intervention characteristics, intensity-dependent effects were present, such that higher intensities yielded larger reductions to reactivity measures, while limited evidence was present for duration, modality, and timing-dependent effects. Regarding participant fitness/physical activity levels, the effects on stress reactivity were mixed. Future work should standardize the definitions and assessment time points of stress reactivity, as well as investigate the interaction between physiological and psychological stress responses in real-world contexts.

Acute stress imparts a transient benefit to task-switching that is not modulated following a single bout of exercise

Introduction

Cognitive flexibility represents a core component of executive function that promotes the ability to efficiently alternate-or "switch"-between different tasks. Literature suggests that acute stress negatively impacts cognitive flexibility, whereas a single bout of aerobic exercise supports a postexercise improvement in cognitive flexibility. Here, we examined whether a single bout of aerobic exercise attenuates a stress-induced decrement in task-switching.

Materials and Methods

Forty participants (age range = 19-30) completed the Trier Social Stress Test (TSST) and were randomized into separate Exercise or Rest groups entailing 20-min sessions of heavy intensity exercise (80% of heart rate maximum via cycle ergometer) or rest, respectively. Stress induction was confirmed via state anxiety and heart rate. Task-switching was assessed prior to the TSST (i.e., pre-TSST), following the TSST (i.e., post-TSST), and following Exercise and Rest interventions (i.e., post-intervention) via pro- (i.e., saccade to veridical target location) and antisaccades (i.e., saccade mirror-symmetrical to target location) arranged in an AABB task-switching paradigm. The underlying principle of the AABB paradigm suggests that when prosaccades are preceded by antisaccades (i.e., task-switch trials), the reaction times are longer compared to their task-repeat counterparts (i.e., unidirectional prosaccade switch-cost).

Results

As expected, the pre-TSST assessment yielded a prosaccade switch cost. Notably, post-TSST physiological measures indicated a reliable stress response and at this assessment a null prosaccade switch-cost was observed. In turn, post-intervention assessments revealed a switch-cost independent of Exercise and Rest groups.

Conclusion

Accordingly, the immediate effects of acute stress supported improved task-switching in young adults; however, these benefits were not modulated by a single bout of aerobic exercise.

A single session of exercise reduces blood pressure reactivity to stress: a systematic review and meta-analysis

Stressful situations are common in everyday life and disturb homeostasis. So, an exercise session is a strategy to mitigate blood pressure (BP) peaks in response to stress (i.e., BP reactivity), decreasing the cardiovascular risk. This is a systematic review and meta-analysis that aims to verify the effects of a single session of physical exercises on BP reactivity to stress in adults. The searches were performed in digital databases (MEDLINE, LILACS, EMBASE, SPORTDiscus, and PsycInfo) and 29 studies were included, totaling 795 individuals (quantitative analysis: k = 25, n = 659). As for exercise characteristics, 21 of the 29 studies focused on aerobic exercises, and 23 studies focused on low to moderate intensities. As for the stress tests, we have them in the following order from the most to the least frequent: stroop color and word test, cold pressor test, arithmetic test, public speaking, handgrip, trier social stress test, and study task. Favorable metanalytic results (standardized mean differences through random-effects approach) for the exercises were found, with attenuated reactivity in systolic BP (pooled effect size = - 0.38 [- 0.49; - 0.27], representing average reductions of 3.7 ± 3.8 mmHg), diastolic BP (pooled effect size = - 0.51 [- 0.70; - 0.33], representing average reductions of 2.9 ± 3.7 mmHg), and mean BP (pooled effect size = - 0.51 [- 0.72; - 0.31], representing average reductions of 4.1 ± 3.3 mmHg). So, acute physical exercise lowers systolic, diastolic, and mean blood pressure reactivity in response to stressor tasks. However, given the small magnitude of effects, the clinical relevance of this result must be interpreted with caution and be better explored.

Can Acute Exercise Lower Cardiovascular Stress Reactivity? Findings from a Scoping Review

Exaggerated cardiovascular reactivity to and delayed recovery from stress increase the risk of cardiovascular diseases in the future. While exercise training has been shown to attenuate stress-induced cardiovascular reactivity and enhance recovery from stress, the effects with acute exercise are less characterized. The aim of this scoping review was to explore the range and characteristics of published evidence regarding acute exercise on cardiovascular reactivity and stress recovery. The secondary objective was to highlight research gaps and implications for future research. A total of 36 articles met the review inclusion/exclusion criteria, involving 1200 participants from various age groups, fitness and health status. Blood pressure (BP) reactivity was the most measured outcome, followed by heart rate (HR) reactivity, and to some extent, heart rate variability. Overall, acute exercise particularly of the moderate-intensity aerobic type effectively reduced stress-induced BP reactivity in the general population. The effects on HR reactivity and cardiovascular recovery were inconclusive. Further research would be recommended to establish if other forms of exercise intensity or type are equally beneficial to lower exaggerated cardiovascular responses to stress. Despite methodological differences and limitations, the available evidence supports the therapeutic potential of acute exercise in addressing the ill effects of stress on cardiovascular health.

Joint associations of regular exercise and healthy diet with psychobiological stress reactivity in a healthy male sample

Objectives: Engaging in physical activity and exercise have long been shown to have beneficial effects on (psychosocial) stress reactivity. Initial studies could reveal that these positive effects on stress reactivity also exist for a healthy diet. Aim of this study was to examine whether combining a healthy diet and regular exercise can provide additional benefits on psychobiological stress levels. Methods: Forty-two men self-identifying as non-exercisers or regular exercisers between 18 and 30 years were exposed to the Trier Social Stress Test for Groups. Salivary cortisol (sCort) and alpha-amylase (sAA) as biological stress markers, and self-reported momentary stress were repeatedly examined. Questionnaires on regular exercise and dietary intake were completed once. Results: Two-stage hierarchical multiple regressions predicting participants' stress reactivity, i.e. response and recovery, from diet quality, exercise as well as their interaction appeared inconsistent. sCort response was significantly predicted by regular exercise whereas greater sCort recovery was predicted by higher diet quality. In contrast, higher sAA reactivity was predicted by higher diet quality while participants eating less healthy and exercising more showed the most pronounced sAA recovery. None of the other outcome variables was predicted by the interaction. Subjective stress was unrelated to either health behavior. Conclusions: The present examination among an all-male sample emphasized the stress-buffering capabilities of regular exercise and provided initial evidence for a distinct link to healthy diet. Assumed synergistic benefits could, however, not be confirmed. Advances are needed to better understand how individuals profit the most from which behaviors as well as their interactive effects.

Early targeted heart rate aerobic exercise versus placebo stretching for sport-related concussion in adolescents: a randomised controlled trial

BACKGROUND

Sport-related concussion is a public health problem, particularly in adolescents. Quality of life is reduced in adolescents with persistent post-concussive symptoms (symptoms >28 days). We replicated a previous randomised controlled trial to validate the safety, efficacy, and generalisability of, and objective adherence to, prescribed early targeted heart rate subsymptom threshold aerobic exercise compared with placebo-like stretching exercise for adolescent recovery from sport-related concussion and for reducing the risk of persistent post-concussive symptoms.

METHODS

This randomised controlled trial was done at three community and hospital-affiliated sports medicine concussion centres in the USA. Male and female adolescent athletes (aged 13-18 years) presenting within 10 days of sport-related concussion were randomly assigned to individualised subsymptom threshold aerobic or stretching exercise at least 20 min daily, for up to 4 weeks after injury. Exercise adherence and intensity were measured by heart rate monitors. The primary outcome was clinical recovery (ie, return to baseline symptoms, normal exercise tolerance, and a normal physical examination) within the 4-week intervention period, and development of persistent post-concussive symptoms beyond 28 days after injury. This study is registered with ClinicalTrials.gov, NCT02959216.

FINDINGS

Between Aug 1, 2018, and March 31, 2020, 118 adolescents were recruited (61 were randomly assigned to the aerobic exercise group and 57 to the stretching exercise group) and included in the intention-to-treat analysis. On survival analysis, controlling for sex, site, and mean daily exercise time, patients assigned to aerobic exercise were more likely to recover within 4 weeks after injury compared with those assigned to stretching exercise, with a 48% reduced risk of persistent post-concussive symptoms (hazard ratio for stretching vs aerobic exercise of 0·52 [95% CI 0·28-0·97], p=0·039). No adverse events were reported.

INTERPRETATION

This multicentre study found that early treatment with subsymptom threshold aerobic exercise safely speeds recovery from sport-related concussion and reduces the risk for persistent post-concussive symptoms, an important result given the impact of delayed recovery on adolescent quality of life. Adherence was good and there were no adverse events from this non-pharmacological treatment. These results suggest that physicians should not only permit, but consider prescribing, early subsymptom threshold physical activity to adolescents as treatment for sport-related concussion and to reduce the risk of persistent post-concussive symptoms.

FUNDING

American Medical Society for Sports Medicine.

Attenuation of stress-induced cardiovascular reactivity following high-intensity interval exercise in untrained males

Exaggerated cardiovascular (CV) reactivity to stress is associated with negative cardiovascular outcomes. This study aimed to investigate the effects of acute high-intensity interval exercise (HIIE) and moderate-intensity exercise (MIE) on CV reactivity in response to a stress challenge in untrained males. Thirteen, normotensive males (age: 22.8 ± 2 years, BMI: 21.9 ± 3.6 kg/m²) underwent three conditions in counterbalanced order: HIIE (bodyweight exercises; 80-90% HRR), MIE (treadmill-jog; 55-60% HRR) and seated rest (CON) separated by 7-10 days. Thirty minutes after performing HIIE, MIE or CON, subjects underwent a 2-min cold pressor task (CPT). Blood pressure (BP) and heart rate (HR) were measured before, during, and after CPT. CV reactivity, i.e., the change in BP and HR responses were compared across conditions. Systolic BP reactivity were attenuated following HIIE (-60%, p = 0.015) and MIE (-42%, p = 0.033) compared to CON, but no differences were observed between HIIE and MIE. HR reactivity was not different across all conditions. We conclude that performing HIIE or MIE 30 minutes prior to acute stress exposure lowers BP reactivity compared to rest in untrained males. These findings highlight the potential benefits of HIIE in lowering stress-induced elevations in blood pressure.

Acute aerobic exercise increases respiratory sinus arrythmia reactivity and recovery to a sad film among individuals at risk for depression

Cardiac vagal control (CVC), as indexed by abnormalities in resting, reactivity, and recovery levels of respiratory sinus arrythmia (RSA), has been proposed as an index of impaired self-regulatory capacity in depression. Aerobic exercise has been shown to improve positive and negative affective responses and influence autonomic function; however, it is unknown whether exercise impacts RSA reactivity and subsequent recovery to emotional challenges among individuals at risk for depression. The present study aimed to determine the effects of moderate-intensity aerobic exercise on RSA reactivity and recovery to a sad film. Using a within-subjects design, 47 individuals with variable symptoms of depression completed a 30-min session of exercise and a sedentary control condition on separate days prior to viewing a sad film. On the control day, individuals with elevated depressive symptom severity displayed less vagal withdrawal to the sad film and exhibited impaired post-film RSA recovery. Following exercise, individuals with elevated depressive symptom severity demonstrated a higher degree of vagal withdrawal to the sad film and subsequent post-film recovery that matched individuals with lower depressive symptom severity. These findings suggest that a single session aerobic exercise may be an effective approach to increase emotional and self-regulatory capacity among individual at risk for, or currently experiencing, depression.

Institutional Guidelines for Resistance Exercise Training in Cardiovascular Disease: A Systematic Review

BACKGROUND

Institutional position stands are useful for practitioners when designing exercise routines for specific populations. Resistance training has been included in programs for patients with cardiovascular disease.

OBJECTIVE

The objective of this systematic review was to analyze institutional guidelines providing recommendations for resistance training applied to cardiovascular disease.

METHODS

PubMed, Web of Science, and Scopus databases were searched from inception until 30 April, 2018.

RESULTS

Of 994 articles initially found, 13 position stands were retained. Consensual indications occurred only for number of sets (one to three sets) and training frequency (two to three sessions/week). Recommendations concerning other major training variables were discordant regarding workload (none or loads ranging from < 30% up to 80% 1 repetition maximum) and exercise order (none or vaguely indicating alternation of muscle groups or circuit format), or insufficient regarding intervals between sets and exercises or number and type of exercises. Overall, guidelines lack recommendations of specific procedures for each type of disease at different severity levels, cardiovascular risk during exercise, or criteria for training progression.

CONCLUSIONS

Recommendations provided by institutional guidelines appear to be insufficient to support adequate resistance training prescription in the context of cardiovascular disease.

Habitual and acute exercise effects on salivary biomarkers in response to psychosocial stress

OBJECTIVE

Previous research suggests beneficial effects of physical exercise on stress reactivity due to cross-stressor adaptions of physiological stress response systems. However, results remain inconclusive and it is unclear whether only regular engagement in exercise modulates these physiological adaptations or if acute bouts of exercise can elicit similar adaptations. Thus, the aim of the current study was to investigate and compare the effects of habitual and acute exercise on physiological stress responses.

METHODS

84 male participants between 18 and 30 years (half of them were screened to be habitually high active or low active) were randomized into one of two groups: either an acute exercise intervention group (n = 42 with 50% being habitually high active) which engaged in 30 min of moderate-to-high intensity ergometer bicycling, or a control (placebo exercise) group which engaged in 30 min of light stretching (n = 42 with 50% being habitually high active). Following the intervention period, participants took part in a well validated psychosocial stress paradigm. Saliva samples were taken repeatedly to derive alpha-amylase and cortisol as stress-specific parameters. A multilevel growth curve approach was applied to analyse changes in the stress parameters over time.

RESULTS

Both, acute and habitual exercise have shown to be positively related to stress reactivity. In particular, a reduction in stress activation was found for both types of exercise, but only habitual engagement in exercise exhibited a beneficial effect on peak cortisol levels.

CONCLUSIONS

Taken together, people can profit from regular exercise (i.e. reduced activity of stress-response systems). However, even acute bouts of exercise preceding stress exposure showed beneficial effects on stress reactivity. This finding is particularly important as it may provide a (self-)regulatory mechanism for people facing conceivable acute stress situations.

Physical activity as an adjunct treatment for erectile dysfunction

Increasing data are available to suggest that physical activity and lifestyle modification in general can benefit erectile function, with effect sizes comparable with established treatment options such as testosterone therapy and phosphodiesterase type 5 inhibitors. Despite this evidence, primary-care physicians are rarely afforded critical information on the underlying mechanisms through which physical activity works as a treatment, severely hampering treatment credibility for both physician and patient. Physical activity is associated with psychological and metabolic adaptations that are compatible with the adaptations required for the treatment of erectile dysfunction (ED). These adaptations include increased expression and activity of nitric oxide synthase, strengthened endothelial function, acute rises in testosterone, decreased stress and anxiety, and improved body image. Use of physical activity as a first-line treatment option for ED is limited, and explicit physical activity guidelines for the treatment of ED are required. Such guidelines should include not only a suggested exercise programme but also guidelines for physician-patient communication that might enhance patient receptivity and therapy continuation. An understanding of how physical activity affects erectile function, as well as its effectiveness in treating ED compared with other established treatments, can benefit urologists and primary-care physicians searching for noninvasive treatment options for men presenting with poor erectile function.

Exercise is Medicine for Concussion

Sport-related concussion (SRC) is a physiological brain injury that produces cerebral and systemic effects, including exercise intolerance. Exercise intolerance after concussion is believed to be the result of autonomic nervous system (ANS) dysfunction. Ventilation is inappropriately low for the level of exercise intensity, raising arterial carbon dioxide (PaCO2) levels. Elevated PaCO2 increases cerebral blood flow (CBF) out of proportion to exercise intensity, which is associated with symptoms that limit exercise performance. Thus, elevated exercise PaCO2 may signal incomplete recovery from SRC. This article reviews recent observational and experimental data and presents the evidence that subthreshold aerobic exercise normalizes the cerebrovascular physiological dysfunction and is "medicine" for patients with concussion and persistent postconcussive symptoms (PPCS). It discusses the systematic evaluation of exercise tolerance after concussion using the Buffalo Concussion Treadmill Test (BCTT) and reviews the utility of the Buffalo Concussion Bike Test (BCBT), the data from which are used to establish an individualized heart rate "dose" of subthreshold exercise to safely speed recovery, which also may work in the acute recovery phase after SRC with the potential to reduce the incidence of PPCS. Evaluation and treatment approaches based on the physiology of concussion suggest that exercise is medicine for concussion, potentially adding a new dimension to concussion care to help safely speed recovery and prevent PPCS in some patients.

Driving in an urban environment, the stress response and effects of exercise

Driving may be detrimental to health, with one hypothesis suggesting that driving may elicit an acute stress response and, with repeated exposures, may become a chronic stressor. The present study examined the stress response to driving and the effectiveness of a prior exercise bout in dampening this response. Twenty healthy adults performed three tasks: control, driving and exercise plus driving. Heart rate (HR), heart rate variability (HRV), blood pressure (BP) and cortisol were measured to quantify the acute stress response to each condition. Data indicated a stress response to driving: HR was elevated and HRV was reduced during the driving task compared with control. HR was elevated and HRV was reduced comparing the exercise plus driving with the driving condition. BP and cortisol were not different among conditions. The potential of interventions, such as exercise, to counter daily stressors should be evaluated to safeguard long-term health. Practitioner Summary: this study confirms that driving induces a stress response, with the exercise intervention providing mixed results (an increase in cardiovascular measures and a decrease in cortisol measure trending significance). Given the known consequences of stress and evidence that exercise can mitigate acute stress, further evaluation of exercise interventions is recommended.

The Role of Chronic Psychosocial Stress in Explaining Racial Differences in Stress Reactivity and Pain Sensitivity

OBJECTIVE

To examine the role of psychosocial factors in mediating the relationship between African American (AA) race and both increased pain sensitivity and blunted stress reactivity.

METHODS

Participants included 133 AA and non-Hispanic white (nHW) individuals (mean [SD] age, 37 [9]) matched for age, sex, and socioeconomic status. Participants underwent mental stress testing (Trier Social Stress Test) while cardiovascular, hemodynamic, and neuroendocrine reactivity were measured. Participants completed questionnaires assessing potential sources of psychosocial stress and were tested for pain responses to cold pain and the temporal summation of heat pulses. Mediation analyses were used to determine the extent to which exposure to psychosocial stress accounted for the observed racial differences in stress reactivity and pain.

RESULTS

Chronic stress exposure and reactivity to mental stress was largely similar among AAs and nHWs; however, AAs exhibited heightened pain to both cold (p = .012) and heat (p = .004). Racial differences in the relationship between stress reactivity and pain were also observed: while greater stress reactivity was associated with decreased pain among nHWs, reactivity was either unrelated to or even positively associated with pain among AAs (e.g., r = -.21 among nHWs and r = .41 among AAs for stroke volume reactivity and cold pressor intensity). Adjusting for minor racial differences in chronic psychosocial stress did not change these findings.

CONCLUSIONS

Accounting for psychosocial factors eliminated racial differences in stress reactivity but not racial differences in sensitivity to experimental pain tasks. Increased exposure to chronic stress may not explain AAs' increased pain sensitivity in laboratory settings.

The blood pressure-lowering effect of a single bout of resistance exercise: A systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Current exercise guidelines recommend aerobic types of exercises on most days of the week, supplemented with dynamic resistance exercise twice weekly. Whereas the blood pressure (BP)-lowering effects of a single session of aerobic exercise have been well studied, less is known about the hypotensive effect of a single bout of resistance exercise.

OBJECTIVES

To evaluate the transient effect of resistance exercise on BP by means of meta-analytic techniques.

METHODS

A systematic electronic search in Medline, Scientific Electronic Library Online (SciELO), Latin American and Caribbean Health Sciences Literature (LILACS), Elton B Stephens Company (EBSCO), EMBASE and SPORTDiscus was completed in March 2015 identifying randomised controlled trials investigating the effect of a single bout of resistance exercise on resting or ambulatory BP in healthy adults. A subsequent meta-analysis was performed.

RESULTS

The meta-analysis involved 30 studies, 81 interventions and 646 participants (normotensive (n = 505) or hypertensive (n = 141)). A single bout of resistance exercise elicited small-to-moderate reductions in office systolic BP at 60 minutes postexercise [-3.3 (-4.0 to -2.6)/-2.7 (-3.2 to -2.1) mmHg (CI 95%)], 90 minutes postexercise [-5.3 (-8.5 to -2.1)/-4.7 (-6.9 to -2.4) mmHg (CI 95%)] and in 24-hour ambulatory BP [-1.7 (-2.8 to -0.67)/-1.2 (-2.4 to -0.022) mmHg (CI 95%)] compared to a control session. The reduction in office BP was more pronounced in hypertensive compared to normotensive individuals (p < 0.01), when using larger muscle groups (p < 0.05) and when participants were recovering in the supine position (p < 0.01).

CONCLUSION

A single bout of resistance exercise can have a BP-lowering effect that last for up to 24 hours. Supine recovery and the use of larger muscle groups resulted in greater BP reductions after resistance exercise.

Hemodynamic mechanisms of the attenuated blood pressure response to mental stress after a single bout of maximal dynamic exercise in healthy subjects

To determine the hemodynamic mechanisms responsible for the attenuated blood pressure response to mental stress after exercise, 26 healthy sedentary individuals (age 29 ± 8 years) underwent the Stroop color-word test before and 60 min after a bout of maximal dynamic exercise on a treadmill. A subgroup (N = 11) underwent a time-control experiment without exercise. Blood pressure was continuously and noninvasively recorded by infrared finger photoplethysmography. Stroke volume was derived from pressure signals, and cardiac output and peripheral vascular resistance were calculated. Perceived mental stress scores were comparable between mental stress tests both in the exercise (P = 0.96) and control (P = 0.24) experiments. After exercise, the systolic blood pressure response to mental stress was attenuated (pre: 10 ± 13 vs post: 6 ± 7 mmHg; P < 0.01) along with lower values of systolic blood pressure (pre: 129 ± 3 vs post: 125 ± 3 mmHg; P < 0.05), stroke volume (pre: 89.4 ± 3.5 vs post: 76.8 ± 3.8 mL; P < 0.05), and cardiac output (pre: 7.00 ± 0.30 vs post: 6.51 ± 0.36 L/min; P < 0.05). Except for heart rate, the hemodynamic responses and the mean values during the two mental stress tests in the control experiment were similar (P > 0.05). In conclusion, a single bout of maximal dynamic exercise attenuates the blood pressure response to mental stress in healthy subjects, along with lower stroke volume and cardiac output, denoting an acute modulatory action of exercise on the central hemodynamic response to mental stress.

Physical exercise ameliorates deficits induced by traumatic brain injury

The extent and depth of traumatic brain injury (TBI) remains a major determining factor together with the type of structural insult and its location, whether mild, moderate or severe, as well as the distribution and magnitude of inflammation and loss of cerebrovascular integrity, and the eventual efficacy of intervention. The influence of exercise intervention in TBI is multiple, ranging from anti-apoptotic effects to the augmentation of neuroplasticity. Physical exercise diminishes cerebral inflammation by elevating factors and agents involved in immunomodulatory function, and buttresses glial cell, cerebrovascular, and blood-brain barrier intactness. It provides unique non-pharmacologic intervention that incorporate different physical activity regimes, whether dynamic or static, endurance or resistance. Physical training regimes ought necessarily to be adapted to the specific demands of diagnosis, type and degree of injury and prognosis for individuals who have suffered TBI.

Cardiovascular and autonomic responses after exercise sessions with different intensities and durations

BACKGROUND

Several studies have reported the phenomenon of post-exercise hypotension. However, the factors that cause this drop in blood pressure after a single exercise session are still unknown.

OBJECTIVE

To investigate the effects of aerobic exercise on the acute blood pressure response and to investigate the indicators of autonomic activity after exercise.

METHODS

Ten male subjects (aged 25 ± 1 years) underwent four experimental exercise sessions and a control session on a cycle ergometer. The blood pressure and heart rate variability of each subject were measured at rest and at 60 min after the end of the sessions.

RESULTS

Post-exercise hypotension was not observed in any experimental sessions (P > 0.05). The index of parasympathetic neural activity, the RMSSD, only remained lower than that during the pre-exercise session after the high-intensity session (Δ = -19 ± 3.7 for 15-20 min post-exercise). In addition, this value varied significantly (P < 0.05) between the high- and low-intensity sessions (Δ = -30.7 ± 4.0 for the high intensity session, and Δ = -9.9 ± 2.5 for the low intensity session).

CONCLUSION

The present study did not find a reduction in blood pressure after exercise in normotensive, physically active young adults. However, the measurements of the indicators of autonomic neural activity revealed that in exercise of greater intensity the parasympathetic recovery tends to be slower and that sympathetic withdrawal can apparently compensate for this delay in recovery.

Ethnic differences in cardiovascular-somatosensory interactions and in the central processing of noxious stimuli

Ethnic differences in central sensitization of pain processing and stress-relevant endogenous pain regulatory mechanisms were examined. Forty-four African Americans (AAs; 50% women) and 44 non-Hispanic Whites (nHWs; 50% women) matched for socioeconomic status, were tested for pain responses to the temporal summation of heat pulses and ischemic and cold pain. Resting and stress blood pressure (BP) and norepinephrine (NE) were assessed. AAs had heightened pain responses to all 3 pain tasks relative to nHWs. In nHWs, higher BP and NE were related to reduced pain. In AAs, there was no relationship between BP and pain, but higher NE was related to increased pain. This study provides evidence for ethnic differences in centrally mediated pain and extends prior research demonstrating ethnic differences in endogenous pain regulatory mechanisms. These results have implications for understanding biobehavioral factors contributing to ethnic disparities in clinical pain.

Isometric handgrip exercise improves acute neurocardiac regulation

Isometric handgrip (IHG) training (>6 weeks) has been shown to reduce resting arterial blood pressure (ABP) and improve cardiac autonomic modulation. However, the effects of a single bout of IHG on acute neurocardiac regulation remain unknown. The purpose of this study was to examine the effect of IHG exercise on nonlinear heart rate dynamics and cardiac vagal activity. Nonlinear dynamics were assessed by sample entropy, detrended fluctuation analysis (alpha(1)), and correlation dimension techniques. The 4-second exercise test was used to calculate the cardiac vagal index (CVI), an indirect measure of cardiac vagal activity. In a randomized crossover design, 18 older (70 +/- 5 years of age) subjects completed IHG exercise (four 2-min isometric contractions at 30% MVC) and a time-matched control condition. Following a single bout of bilateral IHG, there was a small reduction in systolic blood pressure (125 +/- 2 to 122 +/- 1 mmHg, P < 0.01), in addition to, a significant decrease in alpha(1) (1.42 +/- 0.12 to 1.22 +/- 0.10, P < 0.05), an increase in sample entropy (1.28 +/- 0.03 to 1.40 +/- 0.05, P < 0.001), and an increase in the CVI (1.24 +/- 0.03 to 1.29 +/- 0.03, P < 0.01). These results suggest improvements in acute cardiac autonomic modulation following a single bout of IHG. This may be mechanistically linked to the observed reductions in ABP seen in previous IHG training studies. Alternatively, these acute effects may have clinical applications and require further investigation.

Hipotensão pós-exercício aeróbio: uma revisão sistemática

Diversos estudos investigaram os efeitos hipotensores após uma sessão de exercício aeróbio em humanos. No entanto, vários aspectos permanecem obscuros em relação à hipotensão pós-exercício (HPE), uma vez que diversas variáveis podem influenciar a resposta hipotensora, como intensidade, duração, tipo de exercício, estado clínico, faixa etária, etnia, sexo e estado de treinamento. Nesse sentido, o objetivo do presente estudo foi revisar sistematicamente a literatura, relacionando as principais variáveis da prescrição de uma sessão de exercício aeróbio e a HPE, assim como apresentar os possíveis mecanismos envolvidos. Foram encontrados 55 estudos que abrangeram a temática HPE e exercício aeróbio em humanos. A ocorrência da HPE está bem estabelecida na literatura, já que vários estudos identificaram reduções da pressão arterial em normotensos e hipertensos. Porém, os possíveis moduladores das respostas hipotensoras, como intensidade e duração da sessão de exercício, ainda são contraditórios. Em relação ao tipo de exercício, porém, existem indicativos de que os realizados de forma intermitente e que utilizam maior massa muscular podem acarretar maior HPE. Além disso, hipertensos devem apresentar maior magnitude e duração da HPE. Contudo, existem lacunas em relação aos diversos mecanismos fisiológicos envolvidos, que parecem ser diferentes entre normotensos e hipertensos.