Can blood pressure decrease after maximal exercise test predict the blood pressure lowering effect of aerobic training in treated hypertensive men?

The acute decrease in blood pressure (BP) observed after a session of exercise (called post-exercise hypotension) has been proposed as a tool to predict the chronic reduction in BP induced by aerobic training. Therefore, this study investigated whether post-exercise hypotension observed after a maximal exercise test is associated to the BP-lowering effect of aerobic training in treated hypertensives. Thirty hypertensive men (50 ± 8 years) who were under consistent anti-hypertensive treatment underwent a maximal exercise test (15 watts/min until exhaustion), and post-exercise hypotension was determined by the difference between BP measured before and at 30 min after the test. Subsequently, the patients underwent 10 weeks of aerobic training (3 times/week, 45 min/session at moderate intensity), and the BP-lowering effect of training was assessed by the difference in BP measured before and after the training period. Pearson correlations were employed to evaluate the associations. Post-maximal exercise test hypotension was observed for systolic and mean BPs (-8 ± 6 and -2 ± 4 mmHg, all P < 0.05). Aerobic training reduced clinic systolic/diastolic BPs (-5 ± 6/-2 ± 3 mmHg, both P < 0.05) as well as awake and 24 h mean BPs (-2 ± 6 and -2 ± 5 mmHg, all P < 0.05). No significant correlation was detected between post-exercise hypotension and the BP-lowering effect of training either for clinic or ambulatory BPs (r values ranging from 0.00 to 0.32, all p > 0.05). Post-exercise hypotension assessed 30 min after a maximal exercise test cannot be used to predict the BP-lowering effect of aerobic training in treated hypertensive men.

Can postexercise hypotension also be observed in African and Asian populations: a systematic review and meta-analysis of randomized controlled trials.

Worldwide, raised blood pressure (BP) or hypertension is the global leading risk factor for the development of cardiovascular diseases and all-cause mortality, with the highest prevalence found in Asian and African origin populations. Post-exercise hypotension (PEH), defined as a sustained reduction in BP after a single bout of exercise is an important physiological phenomenon in BP management. However, little is known about the hypotensive effect of a single bout of exercise in non-Caucasian populations. We systematically summarized the acute effects of a single bout of aerobic exercise on BP in a population of African or Asian origin. We searched the MEDLINE database identifying randomized controlled trials investigating the effect of a single bout of aerobic exercise on BP in African or Asian populations with optimal BP, high normal BP or hypertension published in a peer reviewed journal up to August 2021. A subsequent meta-analysis was performed using random-effect models fitted to estimate effect sizes. We identified 10 aerobic exercise trials performed in individuals of Asian origin (n = 136; mean age: 29.51 (21.2-69) years: 78% male; baseline systolic BP/diastolic BP: 118.9 ± 9.64/68.9 ± 2.69 mmHg) and 11 aerobic exercise trials involving individuals of African origin (n = 157; mean age: 41.05 (29.9-49) years; 59% male; baseline systolic BP/diastolic BP: 134.5 ± 8.65 mmHg/82.2 ± 3.24 mmHg). Non-significant reductions in office systolic BP and diastolic BP at 30 min post exercise (-2.25 [-6.38, 1.88] mmHg, p = 0.28/-1.02 [-2.51, 0.47] mmHg, p = 0.18) and 60 min post exercise (-2.80 [-7.90, 2.28], p = 0.27/-1.95, [-5.66, 1.75], p = 0.3) were observed compared to the control intervention. No statistically significant differences were found between both ethnic groups (p > 0.05). Ambulatory BP was reported only in a few African groups. No effect was found on 24h-systolic BP post exercise, but 24h-diastolic BP was statistically significantly reduced (-1.89 [-3.47, -0.31] mmHg, p < 0.01) after a bout of aerobic exercise compared to the control intervention. The available evidence is insufficient to recommend a single session of aerobic exercise as an efficient tool to lower BP in African and Asian populations. Though, the paucity of data in non-Caucasian populations underscores the need for additional efforts to establish the efficacy of single bouts of exercise, including isometric and dynamic resistance exercise, as a potential non-pharmacological adjunct to help lowering BP in the daily life of descendants of Asian or African origin.

Is postexercise hypotension a method-dependent phenomenon in chronic stroke? A crossover randomized controlled trial.

BACKGROUND: This study assessed the reproducibility of postexercise hypotension (PEH) detection after two bouts of mixed circuit training (MCT) using three approaches that accounts the pre-exercise values and/or a control session (CTL) to calculate PEH [i.e., ( A 1 = post - exercise - pre - exercise ${A}_{1}=\text{post}{\rm{ \mbox{-} }}\text{exercise}-\text{pre}{\rm{ \mbox{-} }}\text{exercise}$ ); ( A 2 = post - exercise - post - CTL ) $({A}_{2}=\text{post}{\rm{ \mbox{-} }}\text{exercise}-\text{post}{\rm{ \mbox{-} }}\text{CTL})$ ; A 3 = ( post - exercise - pre - exercise ) - ( post - CTL - pre - CTL ) ] ${A}_{3}=(\text{post}{\rm{ \mbox{-} }}\text{exercise}-\text{pre}{\rm{ \mbox{-} }}\text{exercise})-(\text{post}{\rm{ \mbox{-} }}\text{CTL}-\text{pre}{\rm{ \mbox{-} }}\text{CTL})]$ in chronic stroke (i.e., ≥6 months poststroke). The proportion of PEH responders determined using different cut-off values for PEH was also compared (4 mmHg vs. minimal detectable difference). METHODS: Seven participants (age: 56 ± 12 years; time post-stroke: 91 ± 55 months) performed two bouts of MCT and a CTL. The MCT involved 10 exercises with 3 sets of 15-repetition maximum, with each set interspersed with 45 s of walking. The systolic (SBP) and diastolic (DBP) blood pressures were assessed 10-min before and every 10-min along 40-min after CTL and MCT. RESULTS: The two-way random intraclass correlation coefficient for single measurements (ICC2,1 ) ranges for SBP were: A1 : 0.580-0.829, A2 : 0.937-0.994, A3 : 0.278-0.774; for DBP: A1 : 0.497-0.916, A2 : 0.133-0.969, A3 : 0.175-0.930. The proportion of PEH responders detected using 4 mmHg or the minimal detectable difference as cut-off values was not different in 97% of analyses (p > 0.05), and higher when using 4 mmHg in 3% of analyses (p = 0.031). The standard error of measurement was ≥4 mmHg in 47% of analyses for SBP, and 40% for DBP. CONCLUSIONS: The most reliable approach for determining PEH in chronic stroke was to subtract the postexercise from the post-CTL values. The proportion of PEH responders was not affected by the cut-off values applied.

Postexercise hypotensive response in stroke patients following acute moderate or high intensity cycling session.

BACKGROUND: Hypertension is highly prevalent in stroke patients and reducing blood pressure is a priority. Aerobic exercise is known to induce postexercise hypotensive responses, but limited studies have documented this concept in stroke patients. The purpose was to investigate the effect of a single bout of moderate intensity continuous training (MICT) and high-intensity interval training (HIIT) on postexercise ambulatory blood pressure with patients with prior ischemic stroke or transient ischemic attack (TIA). METHODS: Ten hypertensive adults (mean age: 70±9 years) with prior ischemic stroke or TIA participated using a randomized crossover design. Ambulatory blood pressure was monitored for up to 8 hours after either ergocycle MICT or HIIT of respectively 50% and 95% of peak power output. Blood pressure was compared to pre-exercise resting measure. RESULTS: HIIT and MICT induced a decrease of systolic blood pressure of -11.0±9.2 mmHg and -4.7±4.5 mmHg respectively (P=0.03) immediately after the exercise. Ambulatory systolic blood pressure showed a steady linear increase (R2=0.90; P<0.001) of ~1.2 mmHg/hour and returned to pre-exercise measure after 8 hours. Effect of the two exercise conditions over time did not significantly differ (P=0.278). Diastolic blood pressure was not affected by both exercises. CONCLUSIONS: Those results suggest that HIIT induce a systolic blood pressure reduction of greater magnitude than MICT immediately after cycling exercise among patients with prior ischemic stroke or TIA. For both exercises, effects on ambulatory blood pressure are similar and persist up to 8 hours.

Consistency of hemodynamic and autonomic mechanisms underlying post-exercise hypotension.

Post-exercise hypotension (PEH) is a clinically relevant phenomenon, but its mechanisms vary between different studies and between the participants within each study. Additionally, it is possible that PEH mechanisms are not consistent in each individual (i.e. within-individual variation), which has not been investigated yet. Thus, the aim of the current study was to assess the within-individual consistency of PEH hemodynamic and autonomic mechanisms. For that, 30 subjects performed 4 sessions divided in 2 blocks (test and retest). In each block, an exercise (cycling, 45 min, 50%VO2peak) and a control (seated rest, 45 min) session was randomly conducted. Blood pressure (BP) and its mechanisms were evaluated pre- and post-interventions. In each block, individual responses were calculated as post-exercise minus post-control, and a response was considered present when its magnitude reached the typical error of the measurement. Consistencies were evaluated by comparing test and retest responses through kappa coefficient (k). PEH consistency was calculated using role sample, while mechanisms consistency was evaluated in those with consistent PEH. Twenty-one (70%) participants showed consistent PEH, 5 (17%) presented PEH in only test or retest and 4 (13%) had absent PEH response, characterising a good consistency (k = 0.510). Regarding mechanisms' responses, good consistency was found for heart rate (k = 0.456), sympathovagal balance (k = 0.438), and baroreflex sensitivity (k = 0.458); while systemic vascular resistance (k = 0.152), cardiac output (k = -0.400), stroke volume (k = -0.055), and sympathetic vasomotor modulation (k = -0.096) presented marginal consistencies. Thus, PEH is a highly consistent physiological phenomenon, although its mechanisms present variable consistencies.

Acute Hemodynamic Responses to Repetitions to Failure Using Different Resistance Exercises and Protocols in Normotensive Men: A crossover study.

The present crossover design study investigated acute hemodynamic responses to two sets of leg press (LP) and bench press (BeP) at 10 and 20 repetition maximum (RM) in ten normotensive young men. At the end of each set, an increase in systolic blood pressure (SBP), heart rate (HR), and rate pressure product (RPP) was observed (p < .01), with no differences between intensities, but SBP was greater during the LP exercise (p < .01). Lower resting values of diastolic blood pressure (DBP) were observed in the post-BeP exercise period (p < .05), suggesting that DBP post-exercise hypotension may be more evident after upper-limb exercise.

The effects of aquatic and land exercise on resting blood pressure and post-exercise hypotension response in elderly hypertensives.

OBJECTIVE: This study compared resting blood pressure (BP) using ambulatory BP monitoring (ABPM) responses in two groups of subjects trained in land exercise (LE) and aquatic exercise (AE), and assessed post-exercise hypotension (PEH) using ABPM, after land- and aquatic-based exercises. METHODS: ABPM (24 hours) was used to measure the baseline BP in elderly hypertensive women trained in LE and AE and the PEH induced by exercise. For this, 40 subjects were evaluated at rest and after a land- or aquatic-based exercise session (aerobic: 75% of reserve heart rate combined with resistance exercise). RESULTS: The daytime BP was lower for AE [systolic BP (SBP) 124 ± 1.0 mmHg, diastolic BP (DBP) 70 ± 1.5 mmHg] than for LE (SBP 134 ± 0.9 mmHg, DBP 76 ± 0.9 mmHg), but there were no differences at night-time. The aquatic exercise-induced PEH in the second hour was maintained at the 24th hour post-exercise. For land exercise-induced PEH, it was maintained at the 12th hour post-exercise. The SBP and DBP were lower at the 24th hour for AE than for LE. CONCLUSIONS: Elderly hypertensive people trained in AE had lower baseline BP during the daytime. SBP and DBP values were lower for individuals trained in AE, and their PEH was more rapid and longer lasting after AE.

Recommendations in Post-exercise Hypotension: Concerns, Best Practices and Interpretation.

Post-exercise hypotension (PEH) is a clinically relevant phenomenon that has been widely investigated. However, the characteristics of study designs, such as familiarization to blood pressure measurements, duration of PEH assessments or strategies to analyze PEH present discrepancies across studies. Thus identifying key points to standardize across PEH studies is necessary to help researchers to build stronger study designs, to facilitate comparisons across studies, and to avoid misinterpretations of results. The goal of this narrative review of methods used in PEH studies was therefore to gather and find possible influencers in the characteristics of study design and strategies to analyze blood pressure. Data found in this review suggest that PEH studies should have at least two familiarization screening visits, and should assess blood pressure for at least 20 min, but preferably for 120 min, during recovery from exercise. Another important aspect is the strategy to analyze PEH, which may lead to different interpretations. This information should guide a priori study design decisions.

Postexercise hypotension in central aortic pressures following walking and its relation to cardiorespiratory fitness.

BACKGROUND: Central aortic blood pressure (BP) is reduced after exercise. The aim of this study was to determine whether cardiorespiratory fitness relates to postexercise reductions in aortic BP. METHODS: Sixteen young adults completed maximal exercise testing for peak oxygen uptake (VO2). Participants walked at a slow (80 steps/min, ~47% maxHR) and fast (125 steps/min, ~65% maxHR) stepping cadence for 3000 steps on two nonconsecutive days. Before and after each walking condition, radial tonometry was used to derive aortic pressures. Measurements after walking were taken after 30 and 60 min of supine recovery. RESULTS: The change in aortic BP was similar between walking cadences. Aortic systolic BP (-2.3 mmHg, P=0.03) and pulse pressure (-3.2 mmHg, P<0.001) were significantly reduced after 60 min of recovery as compared to baseline. The reduction in aortic pulse pressure was associated with decreased forward (r=0.69, P<0.001) and backward wave pressure (r=0.70, P<0.001). Peak VO2 was not associated (P>0.05) with these changes, but was strongly associated with non-significant changes in aortic systolic BP (30min: r=-0.54, P=0.03) and diastolic BP (30 min: r=-0.64, 60 min: r=-0.77; both P<0.01) after slow walking only. CONCLUSIONS: These results indicate that cardiorespiratory fitness associates with aortic pressure reductions after walking dependent on exercise intensity.

Separate aftereffects of morning and evening exercise on ambulatory blood pressure in prehypertensive men.

BACKGROUND: Clinic postexercise hypotension (PEH) is different after aerobic exercise performed in the morning and in the evening. Thus, ambulatory PEH should also differ after exercises conducted at different times of day. However, because of the circadian pattern of blood pressure (BP), ambulatory PEH should be assessed considering a control condition. Thus, this study was designed to verify the effects of morning and evening exercises on postexercise ambulatory BP averages and circadian parameters by comparing responses obtained at each time of day after an exercise and a control session. METHODS: Thirteen prehypertensive men underwent four sessions (randomized order): two in the morning (9 am) and two in the evening (6:30 pm). At each time of day, a control (C) and an exercise (E: cycle ergometer 45 min, 50% VO2peak) sessions were performed. After the sessions, an ambulatory BP and heart rate (HR) monitoring was started for 24 h. Paired t-test or Wilcoxon Signed Rank Test were used to compare the E and the C sessions at each time of day. RESULTS: In the morning, 24 h, daytime and nighttime HR were higher after the E than the C session. In the evening, nighttime systolic BP (116±11 vs. 120±10 mmHg, P=0.04) and rate pressure product (7981±1294 vs. 8583±1523 mmHg.bpm, P=0.04), as well as MESOR (128±11 vs. 130±10 mmHg, P=0.03) were lower in the E than the C session. CONCLUSIONS: In prehypertensive men, morning exercise increased ambulatory HR, while evening exercise decreased nighttime BP and cardiac work, reducing the MESOR of systolic BP.

Angiotensin converting enzyme 2 polymorphisms and postexercise hypotension in hypertensive medicated individuals.

The renin-angiotensin aldosterone system (RAAS) is associated with diverse physiological responses and adaptations to exercise. The angiotensin converting enzyme (ACE) 2 has vasodilatory effects, which might be associated with the blood pressure (BP) responses to acute exercise. The aim of this study was to investigate the role of ACE2 polymorphisms in postexercise hypotension (PEH). Thirty-four medicated hypertensive (61·3 ± 1·7 years, 76·1 ± 2·7 kg, 160 ± 1·6 cm) men (n = 12) and women (n = 22), participated in a control and a moderate intensity exercise session in a randomized order. After both experimental sessions, they left the laboratory wearing an ambulatory BP device for 24-h monitoring. ACE2 polymorphisms (Int-1 and Int-3) were assessed by polymerase chain reaction. Over the course of 5-h monitoring, we observed a significant reduction in SBP and DBP following exercise in the AA/AG of the Int-1 polymorphism (p-interaction = 0·02 and 0·001, respectively), whereas this could not be found in the individuals homozygous G (p-interaction = 0·76 and 0·51, respectively). With regard to Int-3 polymorphism, individuals AA/AG showed a significant reduction in SBP following exercise (p-interaction <0·0001) but not for DBP (p-interaction = 0·06) whereas GG individuals showed only a significant reduction in DBP following exercise (p-interaction = 0·02). Our results suggest that ACE2 polymorphism could affect PEH; however, larger trials are needed to confirm our findings.

Postexercise Hypotension After Aquatic Exercise in Older Women With Hypertension: A Randomized Crossover Clinical Trial.

BACKGROUND: Hypertension can be prevented and modified with lifestyle interventions that include regular exercise. Aquatic exercise is widely recommended for older adults for a variety of health benefits, but few studies have assessed the immediate ambulatory blood pressure (BP) response to aquatic exercise, a response termed postexercise hypotension (PEH). Thus, we assessed PEH after a session of aquatic exercise in physically active, older women with hypertension. METHODS: Twenty-four women 70.0 ± 3.9 years with a resting systolic (SBP)/diastolic (DBP) BP of 124.0/72.3 mm Hg and body mass index of 29.8 ± 4.1 kg/m2 were randomly assigned to participate in a 45-minute session of moderate intensity, water-based exercise (WATER) and a 45-minute land control session (CONTROL). All experimental sessions started at 9 am sharply with 7 days between them. Subjects left the experiments wearing an ambulatory BP monitor for the next 21 hours. RESULTS: SBP was lower by 5.1 ± 1.0 mm Hg after WATER than CONTROL over 21 hours (P < 0.001), over awake hours by 5.7 ± 1.1 mm Hg (P < 0.001), and sleep hours by 4.5 ± 0.4 mm Hg (P = 0.004). DBP was lower following WATER compared to CONTROL: 1.2 ± 0.3 mm Hg over 21 hours (P = 0.043); 0.9 ± 0.6 mm Hg over awake hours (P = 0.101); and 1.4 ± 0.9 mm Hg over sleep hours (P = 0.039). CONCLUSIONS: Aquatic exercise elicited PEH (~5 mm Hg) over 21 hours, BP reductions that are comparable in magnitude to land aerobic exercise. The immediate antihypertensive benefits of acute aquatic exercise should continue to be explored in future studies.

Postexercise Hypotension as a Predictor for Long-Term Training-Induced Blood Pressure Reduction: A Large-Scale Randomized Controlled Trial.

OBJECTIVE: To investigate the correlation between acute exercise effects and chronic training effects on blood pressure (BP). DESIGN: Randomized, controlled training study focusing on the optimization of preventive effects of physical training. SETTING: The study was performed in a university department. PARTICIPANTS: One hundred twenty-seven healthy, untrained subjects. INTERVENTION: Subjects were divided into 4 groups: interval endurance training (IET) (n = 26, 4 × 4 min at 95% maximal heart rate), continuous endurance training (CET) (n = 23, 45 minutes at 60% heart rate reserve), strength endurance training (SET) (n = 40, 8 machine-based exercises, each 2 x 15 repetitions at the 20 repetition maximum), and control (CON) (n = 38). In the 3 training groups, subjects trained 3 times a week for 6 months, the CON group was asked to retain their sedentary lifestyle. MAIN OUTCOME MEASURES: The acute exercise effect on BP was defined as the change of BP after an exhaustive stage test, compared with baseline. The chronic training effect on BP was determined as the change of resting BP after the 6-month training period. RESULTS: For CET, a significant correlation between acute and chronic effects on systolic (r = 0.66, P = 0.001) and diastolic (r = 0.66, P = 0.001) BP was observed. For SET, a significant correlation (r = 0.45, P = 0.007) was found only for diastolic BP. No significant correlations were found for IET. CONCLUSIONS: It can be assumed that postexercise hypotension is an easy-to-use predictor for the efficacy of CET to reduce BP, and may be a valuable tool for physicians to individualize prescribed training schedules for patients to reduce cardiovascular risk. TRIAL REGISTRATION: www.clinicaltrials.gov; ID: NCT01263522.

Reproducibility (Reliability and Agreement) of Post-exercise Hypotension.

This study determined the reproducibility of post-exercise hypotension (PEH) calculated by the following methods: PEH_I=post-exercise BP - pre-exercise BP; PEH_II=post-exercise BP - post-control BP; and PEH_III=[(post-exercise BP - pre-exercise BP)-(post-control BP - pre-control BP)]. Twenty-five participants underwent four sessions divided in two blocks (test and retest). Each block consisted of one exercise and one control session. BP pressure was measured before and after the interventions. The presence of systematic error (paired t-tests), reliability [intraclass coefficient correlation (ICC)], and agreement [typical error (TE) and minimal detectable difference (MDD)] were evaluated. PEHs calculated by the three methods were similar between test and retest. For systolic PEH, ICC was>0.74, TE ranged from 2.6 to 4.6 mmHg and MDD from 7.2 to 12.8 mmHg for the three methods. For diastolic PEH, ICC was<0.48, TE ranged from 3.5 to 5.6 mmHg and MDD from 9.8 to 15.4 mmHg for the three methods. Thus, systolic PEH calculated by the three methods has good/excellent reliability, while diastolic PEH has fair/poor reliability. Regarding agreement, TE and MDD varied among the methods, which implies that the specific parameters given for each method should be used to estimate sample sizes for studies and the minimal individual difference considered real when comparing PEHs.

Effects of concurrent and aerobic exercises on postexercise hypotension in elderly hypertensive men.

Despite the fact that simultaneous performance of resistance and aerobic exercises (i.e., concurrent exercise) has become a standard exercise prescription for the elderly, no information is available on its effects on post-exercise hypotension (PEH) in elderly men with hypertension. PURPOSE: To compare the effects of different types of exercise on PEH in elderly men with hypertension. METHODS: Twenty elderly men with essential hypertension participated in three crossover interventions, in random order, and on separate days: a non-exercise control session at seated rest, aerobic exercise performed for 45min, and 45min of concurrent resistance and aerobic exercise consisted of 4 sets of 8 repetitions at 70% 1RM of resistance exercise followed by aerobic exercise on treadmill. After each session, blood pressure (BP) was measured continuously for 1h in the laboratory and for 24h under ambulatory conditions. RESULTS: During the first hour in laboratory, diastolic BP was lower after aerobic (-5mmHg) and concurrent exercise (-6mmHg) in comparison with Control. Day-time diastolic BP was significantly lower after aerobic exercise (-7mmHg) when compared to the control. No significant differences were found among the three experimental sessions for night-time and 24-hour diastolic BP, as well as day-time, night-time and 24-hour systolic BP. CONCLUSION: Concurrent exercise produced acute PEH similar to aerobic exercise but such effect did not last as long as aerobic exercise in elderly patients with essential hypertension.

Inter- and Intra-Individual Analysis of Post-Exercise Hypotension Following a Single Bout of High-Intensity Interval Exercise and Continuous Exercise: A Pilot Study.

Recently, post-exercise blood pressure (BP) has been considered a predictive tool to identify individuals who are responsive or not to BP reductions with exercise training (i. e., "high" and "low responders"). This study aimed to analyze the inter- and intra-individual BP responsiveness following a single bout of high-intensity interval exercise (HIIE) and continuous exercise (CE) in normotensive men (n=14; 24.5±4.2 years). Mean change in BP during the 60 min period post-exercise was analyzed and minimal detectable change (MDC) was calculated to classify the subjects as "low" (no post-exercise hypotension [PEH]) and "high responders" (PEH occurrence) following each exercise protocol (inter-individual analysis). The MDC for systolic and diastolic BP was 5.8 and 7.0 mmHg. In addition, a difference equal/higher than MDC between the exercise protocols was used to define an occurrence of intra-individual variability in BP responsiveness. There were "low" and "high" PEH responders following both exercise protocols (inter-individual variability) as well as subjects who presented higher PEH following a specific exercise protocol (intra-individual variability between exercise protocols). These results were observed mainly for systolic BP. In summary, PEH is a heterogeneous physiological phenomenon and, for some subjects, seems to be exercise-protocol dependent. Further investigations are necessary to confirm our preliminary findings.

Post-exercise syncope: Wingate syncope test and visual-cognitive function.

Adequate cerebral perfusion is necessary to maintain consciousness in upright humans. Following maximal anaerobic exercise, cerebral perfusion can become compromised and result in syncope. It is unknown whether post-exercise reductions in cerebral perfusion can lead to visual-cognitive deficits prior to the onset of syncope, which would be of concern for emergency workers and warfighters, where critical decision making and intense physical activity are combined. Therefore, the purpose of this experiment was to determine if reductions in cerebral blood velocity, induced by maximal anaerobic exercise and head-up tilt, result in visual-cognitive deficits prior to the onset of syncope. Nineteen sedentary to recreationally active volunteers completed a symptom-limited 60° head-up tilt for 16 min before and up to 16 min after a 60 sec Wingate test. Blood velocity of the middle cerebral artery was measured using transcranial Doppler ultrasound and a visual decision-reaction time test was assessed, with independent analysis of peripheral and central visual field responses. Cerebral blood velocity was 12.7 ± 4.0% lower (mean ± SE; P < 0.05) after exercise compared to pre-exercise. This was associated with a 63 ± 29% increase (P < 0.05) in error rate for responses to cues provided to the peripheral visual field, without affecting central visual field error rates (P = 0.46) or decision-reaction times for either visual field. These data suggest that the reduction in cerebral blood velocity following maximal anaerobic exercise contributes to visual-cognitive deficits in the peripheral visual field without an apparent affect to the central visual field.

Postexercise orthostatic intolerance: influence of exercise intensity.

NEW FINDINGS: What is the central question of this study? Following exercise, hypotension is often reported and syncope is more likely. It is unresolved whether the postexercise hypotension associated with different exercise intensities contributes to the rate at which syncope develops. What is the main finding and its importance? The physiological events that induce presyncope are the same both before and after exercise; however, more intense exercise accelerated the development of hypocapnia, hypotension and, ultimately, syncope. These data indicate that higher intensity exercise induces a postexercise hypotension that reduces cardiovascular reserve, an earlier development of hypocapnia and, ultimately, cerebral hypoperfusion. After exercise, a reduction in mean arterial pressure is often experienced and is referred to as postexercise hypotension. Whilst syncope is more likely following exercise, it is unknown whether orthostatic tolerance is impacted by any exercise intensity-mediated effect on postexercise hypotension. We examined the effect of exercise intensity on time to presyncope, induced via combined head-up tilt and lower body negative pressure following 1 h of cycling at 30 and 70% of heart rate range. Healthy participants (n = 8; mean ± SD, 28 ± 5 years old) completed orthostatic testing to presyncope before and after exercise. Beat-to-beat middle cerebral artery blood flow velocity (MCAv), mean arterial pressure and cerebral oxygenation (measured by near-infrared spectroscopy) were recorded continuously throughout orthostatic testing. During exercise, heart rates were 95 ± 6 and 147 ± 5 beats min(-1) for 30 and 70% heart rate range, respectively, with average power outputs of 103 ± 22 and 221 ± 45 W, respectively. Time to presyncope occurred 32% sooner after the 70% heart rate range trial (952 ± 484 versus 1418 ± 435 s; P = 0.004). Both before and after exercise, presyncope occurred at the same reduction in MCAv (grouped mean, -30 ± 11 cm s(-1) ), mean arterial pressure (-18 ± 13 mmHg), total oxygenation index (-6 ± 2%) and partial pressure of end-tidal CO2 (-16 ± 8 mmHg; all P > 0.1). At presyncope following exercise, the MCAv response was related more to the change in partial pressure of end-tidal CO2 from the baseline preceding orthostatic testing (r(2)  = 0.50, P = 0.01) than to the hypotension (r(2)  = 0.12, P = 0.17). Presyncope both before and after exercise occurred as a result of the same physiological perturbations, albeit greatly accelerated following more intense exercise.

Effects of fractionized and continuous exercise on 24-h ambulatory blood pressure.

PURPOSE: The objective of this study is to compare the effects of fractionized aerobic exercise (three 10-min exercise sessions) and continuous exercise (one 30-min exercise session) on 24-h ambulatory blood pressure (ABP). METHODS: Eleven healthy prehypertensive subjects (28.3 ± 8.0 (SD) yr) completed three randomly assigned conditions: 1) three 10-min sessions of aerobic exercise (3 × 10 min), 2) one continuous 30-min session of aerobic exercise (1 × 30 min), and 3) a nonexercise control trial (control). The mode of exercise was walking on a motor-driven treadmill at 75%-79% of maximum heart rate (HRmax) (60%-65% V˙O2peak). Twenty-four-hour ABP was monitored with an automated ABP device (Oscar 2™; SunTech Medical, Morrisville, NC). Linear mixed models were used to compare 24-h ABP responses between trials. RESULTS: The mean ± SD 24-h systolic blood pressure (SBP) was significantly lower during the 3 × 10-min trial (127 ± 15 mm Hg) compared with control (130 ± 15 mm Hg) (P < 0.001). Although both 3 × 10-min and 1 × 30-min trials reduced SBP compared with control during daytime/evening (1300-2300 h), only the 3 × 10-min trial reduced SBP during nighttime (2300-0800 h, 118 ± 16 vs 122 ± 14 mm Hg, P = 0.024) and the following morning (0800-1200 h, 127 ± 15 vs 131 ± 15 mm Hg, P = 0.016). For 24 h, 26.7% of SBP values during 3 × 10 min were normal (i.e., <120 mm Hg) compared with 18.3% for 1 × 30 min and 19.4% for control (P < 0.001). CONCLUSIONS: In prehypertensive individuals, fractionized exercise (e.g., three 10-min aerobic exercise sessions spread and effective exercise alternative to continuous exercise for cardiovascular risk reduction in this population.