Isometric handgrip training does not improve flow-mediated dilation in subjects with normal blood pressure

Isometric Exercise Training and Arterial Hypertension: An Updated Review

Hypertension is recognised as a leading attributable risk factor for cardiovascular disease and premature mortality. Global initiatives towards the prevention and treatment of arterial hypertension are centred around non-pharmacological lifestyle modification. Exercise recommendations differ between professional and scientific organisations, but are generally unanimous on the primary role of traditional aerobic and dynamic resistance exercise. In recent years, isometric exercise training (IET) has emerged as an effective novel exercise intervention with consistent evidence of reductions in blood pressure (BP) superior to that reported from traditional guideline-recommended exercise modes. Despite a wealth of emerging new data and endorsement by select governing bodies, IET remains underutilised and is not widely prescribed in clinical practice. This expert-informed review critically examines the role of IET as a potential adjuvant tool in the future clinical management of BP. We explore the efficacy, prescription protocols, evidence quality and certainty, acute cardiovascular stimulus, and physiological mechanisms underpinning its anti-hypertensive effects. We end the review with take-home suggestions regarding the direction of future IET research.

Handgrip exercise does not alter CO2 -mediated cerebrovascular flow-mediated dilation

Handgrip exercise (HG), a small muscle exercise, improves cognitive function and is expected to provide a useful exercise mode to maintain cerebral health. However, the effect of HG on cerebral blood flow regulation is not fully understood. The present study aimed to examine the effect of acute HG on cerebral endothelial function as one of the essential cerebral blood flow regulatory functions. Thirteen healthy young participants performed interval HG, consisting of 4 sets of 2 min HG at 25% of maximum voluntary contraction with 3 min recovery between each set. Cognitive performance was evaluated before and at 5 and 60 min after interval HG using the Go/No-Go task (reaction time and accuracy). The diameter and blood velocity of the internal carotid artery (ICA) were measured using a duplex Doppler ultrasound system. To assess cerebral endothelial function, hypercapnia (30 s of hypercapnia stimulation, end-tidal partial pressure of CO2 : +9 mmHg)-induced cerebrovascular flow-mediated dilatation (cFMD) was induced, calculated as relative peak dilatation from baseline diameter. The shear rate (SR) was calculated using the diameter and blood velocity of the ICA. As a result, cognitive performance improved only at 5 min after interval HG (reaction time, P = 0.008; accuracy, P = 0.186), whereas ICA SR during interval HG and cFMD after interval HG were unchanged (P = 0.313 and P = 0.440, respectively). These results suggest that enhancement in cerebral endothelial function is not an essential mechanism responsible for acute HG-induced cognitive improvement. NEW FINDINGS: What is the central question of this study? Does handgrip exercise, a small muscle exercise, improve cerebral endothelial function? What is the main finding and its importance? Acute interval isometric handgrip exercise (2 min of exercise at 25% maximum voluntary contraction, followed by 3 min of recovery, repeated for a total of 4 sets) did not improve cerebral endothelial function. Since the cerebrovascular shear rate did not change during exercise, it is possible that acute handgrip exercise is not sufficient stimulation to improve cerebral endothelial function.

Effects of isometric resistance training and detraining on ambulatory blood pressure and morning blood pressure surge in young normotensives

Isometric resistance training (IRT) has been shown to reduce resting and ambulatory blood pressure (BP), as well as BP variability and morning BP surge (MBPS). However, there are no data available regarding how long after cessation of IRT these effects are maintained. Therefore, the purpose of this study was to determine the effects of 8 weeks of detraining on resting BP, ambulatory BP and MBPS following 8 weeks of IRT in a population of young normotensive individuals and to further substantiate previously reported reductions in MBPS following IRT. Twenty-five apparently healthy participants with resting BP within the normal range (16 men, age = 23 ± 6 years; 9 women, age = 22 ± 4 years, resting BP: 123 ± 5/69 ± 7 mmHg) were randomly assigned to a training-detraining (TRA-DT, n = 13) or control (CON, n = 12) group. Resting BP, ambulatory BP and MBPS were measured prior to, after 8 weeks of bilateral leg IRT using an isokinetic dynamometer (4 × 2-min contractions at 20% MVC with 2-min rest periods, 3 days/week) and following an 8-week detraining period. There were significant reductions in 24-h ambulatory systolic BP (SBP) and calculated SBP average real variability (ARV) following IRT that were maintained after detraining (pre-to-post detraining, −6 ± 4 mmHg, p = 0.008, −2 ± 1.5 mmHg, p = 0.001). Similarly, the training-induced decreases in daytime SBP and daytime SBP ARV (pre-to-post detraining, −5 ± 6 mmHg, p = 0.001; −2 ± 1.2 mmHg, p = 0.001, respectively), MBPS (pre-to-post detraining, −6 ± 9 mmHg, p = 0.046) and resting SBP (pre-to-post detraining, −4 ± 6 mmHg, p = 0.044) were preserved. There were no changes in night-time or night-time SBP ARV across all time points (pre-to-post detraining, −1 ± 8 mmHg, p = 1.00, −0.7 ± 2.9 mmHg, p = 1.00). These results confirm that IRT causes significant reductions in resting BP, ambulatory BP, ambulatory ARV and MBPS. Importantly, the changes remained significantly lower than baseline for 8 weeks after cessation of training, suggesting a sustained effect of IRT.

Effect of Lower- versus Higher-Intensity Isometric Handgrip Training in Adults with Hypertension: A Randomized Controlled Trial

This study compared the effects of lower- versus higher-intensity isometric handgrip exercise on resting blood pressure (BP) and associated clinical markers in adults with hypertension. Thirty-nine males were randomly assigned to one of three groups, including isometric handgrip at 60% maximal voluntary contraction (IHG-60), isometric handgrip at 30% IHG-30, or a control group (CON) that had been instructed to continue with their current activities of daily living. The volume was equated between the exercise groups, with IHG-60 performing 8 × 30-s contractions and IHG-30 performing 4 × 2-min contractions. Training was performed three times per week for 8 weeks. Resting BP (median [IQR]), flow-mediated dilation, heart rate variability, and serum markers of inflammation and oxidative stress were measured pre- and post-intervention. Systolic BP was significantly reduced for IHG-60 (−15.5 mmHg [−18.75, −7.25]) and IHG-30 (−5.0 mmHg [−7.5, −3.5]) compared to CON (p < 0.01), but no differences were observed between both the exercise groups. A greater reduction in diastolic BP was observed for IHG-60 (−5.0 mmHg [−6.0, −4.25] compared to IHG-30 (−2.0 mmHg [−2.5, −2.0], p = 0.042), and for both exercise groups compared to CON (p < 0.05). Flow-mediated dilation increased for both exercise groups versus CON (p < 0.001). IHG-30 had greater reductions in interleukin-6 and tumor necrosis factor-α compared to the other groups (p < 0.05) and CON (p = 0.018), respectively. There was a reduction in Endothelin-1 for IHG-60 compared to CON (p = 0.018). Both the lower- and higher-intensity IHG training appear to be associated with reductions in resting BP and improvements in clinical markers of inflammation and oxidative stress.

The relationship between sleep quality and physical activity among patients with heart failure: a cross-sectional study

BACKGROUND

Sleep disorders are one of the most common and annoying problems among patients with heart failure, which decrease their quality of life. Participation in physical activity is one of the most effective methods to reduce sleep disorders; however, few patients participate. This study was conducted to examine the relationship between physical activities and sleep quality among heart failure patients.

METHODS

A convenience sample of 100 patients with heart failure referred to rehabilitation centers in southeastern Iran was used in this descriptive cross-sectional study. The Pittsburgh Sleep Quality Index and the Rapid Assessment of Physical Activity (RAPA) were used to collect data. The Spearman correlation coefficient and regression were used to analyze the data. The significance level was < 0.05.

RESULTS

The results revealed that the mean score of sleep quality was 8.74 ± 2.83, with the majority of them (84.47%) having poor sleep quality. The mean score of physical activity was 2.59 ± 1.33, and the majority of them (95.15%) had sub-optimal physical activity. There was a significant and inverse relationship between the total scores of sleep quality and physical activity, and patients' sleep quality improved while physical activity increased. Physical activity, sex, history of heart surgery, and the stage of illness were found to account for 31% of the variances in patients' sleep quality.

CONCLUSION

The results of this study showed better sleep quality among patients who were more physically active. Given that the majority of patients with heart failure suffer from sleep disorders, patients' knowledge of physical activity should be increased to improve their quality of sleep and quality of life.

Acute cardiac autonomic and haemodynamic responses to leg and arm isometric exercise

OBJECTIVES

Acute cardiovascular responses following a single session of isometric exercise (IE) have been shown to predict chronic adaptations in blood pressure (BP) regulation. It was hypothesised that exercises which recruit more muscle mass induce greater reductions in BP compared to exercises using smaller muscle mass. To test this hypothesis, the current study aimed to compare the acute haemodynamic and autonomic responses to a single session of isometric wall squat (IWS) and isometric handgrip (IHG) training.

METHODS

Twenty-six sedentary participants performed a single IWS and IHG session in a randomised cross-over design, with training composed of 4 × 2-min contractions, with 2-min rest, at 95 HR_peak and 30% MVC respectively. Haemodynamic and cardiac autonomic variables were recorded pre, during, immediately post, and 1-h post-exercise, with the change from baseline for each variable used for comparative analysis.

RESULTS

During IWS exercise, there was a significantly greater increase in systolic BP (P < 0.001), diastolic BP (P < 0.001), mean BP (P < 0.001), heart rate (P < 0.001), and cardiac output (P < 0.001), and a contrasting decrease in baroreflex effectiveness index (BEI) and cardiac baroreceptor sensitivity (cBRS). In the 10-min recovery period following IWS exercise, there was a significantly greater reduction in systolic BP (P = 0.005), diastolic BP (P = 0.006), mean BP (P = 0.003), total peripheral resistance (TPR) (P < 0.001), BEI (P = 0.003), and power spectral density (PSD-RRI) (P < 0.001). There were no differences in any variables between conditions 1-h post exercise.

CONCLUSIONS

Isometric wall squat exercise involving larger muscle mass is associated with a significantly greater post-exercise hypotensive response during a 10-min recovery window compared to smaller muscle mass IHG exercise. The significantly greater reduction in TPR may be an important mechanism for the differences in BP response.

Effects of resistance training on endothelial function: A systematic review and meta-analysis

BACKGROUND AND AIMS

The effects of resistance training on flow-mediated dilation (FMD), which has been the gold standard non-invasive assessment of endothelial function and is associated with the risk of cardiovascular events, are not well known. We conducted a systematic review to analyze the effects of resistance training on FMD.

METHODS

We searched Pubmed, Embase, CINAHL, SPORTDiscuss, Scopus, Web of Science and PEDro databases for studies that met the following criteria: (a) randomized controlled trials of resistance exercise with a comparative non-exercise group or contralateral untrained limb in adults and/or elderly; (b) studies that measured post-occlusion brachial artery FMD by ultrasonography, before and after intervention. Mean differences (MDs) with 95 % confidence interval (95 % CI) were calculated using an inverse variance method with a random effects model.

RESULTS

Twenty-three studies were included in the meta-analysis (n = 785 participants; 53 % females). Resistance training on FMD responses showed a favorable result for the resistance training group (n = 366) compared to the control group (n = 358) (MD 2.39, 95%CI 1.65, 3.14; p<0.00001). Subgroup analysis indicated favorable results for the dynamic resistance training (n = 545; MD 2.12, 95 % CI 1.26, 2.98; p<0.00001) and isometric handgrip training (n = 179; MD 3.32, 95 % CI 1.68, 4.96; p<0.0001) compared to the control group. The effect of resistance training on FMD responses was also favorable regardless of the condition of the participants (Healthy [n = 261]: MD 2.11, 95 % CI 1.04, 3.18; p<0.0001; Cardiovascular disease [n = 310]: MD 2.89, 95 % CI 0.88, 4.90; p = 0.005; metabolic disease [n = 153]: MD 2.40, 95 % CI 1.59, 3.21; p<0.00001).

CONCLUSIONS

Resistance training improves FMD in healthy individuals and patients with cardiovascular and metabolic diseases.

A brief experimental examination of post-exercise hypotension and the impact of calculation method

PURPOSE

There is great variability in the reported values of post-exercise hypotension (PEH), with inconsistent calculation methods employed across primary research. This study aimed to explore the influence of the mathematical calculation method on PEH variability, with the hypothesis that the method of identifying the lowest single reduction point (LSRP) would yield false-positive results.

METHODS

Young, normotensive (108 ± 7/69 ± 5 mmHg), apparently healthy, male (n = 20) were included in this study. Participants completed three random-order experimental sessions, with blood pressure and heart rate measured before (10 min) and after (30 min) an acute bout of either isometric handgrip exercise, aerobic cycling, or a nonexercise control. Three PEH calculation methods were analyzed: LSRP, 30-min average across the full post-exercise recovery, and 15-min binned averages with two recovery windows (0-15 min, 15-30 min).

RESULTS

The only calculation method to consistently identify PEH was the LSRP method, which identified PEH for SBP, DBP, and mean arterial pressure, across handgrip exercise, aerobic cycling, and even nonexercise control (P < 0.001). All other calculation methods inconsistently identified PEH across experimental sessions, supporting the hypothesis that LSRP inaccurately overreports PEH.

CONCLUSION

Mathematical calculation method appears to be one source of variability contributing to the inconsistency in reported PEH among young, healthy males. This brief experimental examination reveals that the LSRP method should be avoided as it inaccurately overreports PEH. Alternatively, binned averages of smaller time windows across the recovery period may be a potentially advantageous approach and require further examination to determine to ideal level of granularity.

Validity and reliability of the 'Isometric Exercise Scale' (IES) for measuring ratings of perceived exertion during continuous isometric exercise

Isometric exercise (IE) interventions are an effective non-medical method of reducing arterial blood pressure (BP). Current methods of prescribing and controlling isometric exercise intensity often require the use of expensive equipment and specialist knowledge. However, ratings of perceived exertion (RPE) may provide a more accessible means of monitoring exercise intensity. Therefore, the aim of this study was to assess the validity of a specific Isometric Exercise Scale (IES) during a continuous incremental IE test. Twenty-nine male participants completed four incremental isometric wall squat tests. Each test consisted of five 2-min stages of progressively increasing workload. Workload was determined by knee joint angle from 135° to 95°. The tests were continuous with no rest periods between the stages. Throughout the exercise protocol, RPE (IES and Borg’s CR-10), heart rate and blood pressure were recorded. A strong positive linear relationship was found between the IES and the CR-10 (r = 0.967). Likewise, strong positive relationships between the IES and wall squat duration (r = 0.849), HR (r = 0.819) and BP (r = 0.841) were seen. Intra-class correlation coefficients and coefficients of variations for the IES ranged from r = 0.81 to 0.91 and 4.5–54%, respectively, with greater reliability seen at the higher workloads. The IES provides valid and reliable measurements of RPE, exercise intensity, and the changes in physiological measures of exertion during continuous incremental IE; as such, the IES can be used as an accessible measure of exercise intensity during IE interventions.

Effects of isometric handgrip training on blood pressure among hypertensive patients seen within public primary healthcare: a randomized controlled trial

BACKGROUND

Meta-analyses have demonstrated that isometric handgrip training (IHT) decreases blood pressure in hypertensive individuals. Nonetheless, most studies were conducted in laboratory settings and its effects in real-world settings remain unclear.

OBJECTIVE

To analyze the effects of IHT on office and ambulatory blood pressure in hypertensive patients attended within primary healthcare.

DESIGN AND SETTING

Randomized controlled trial conducted in primary healthcare units within the Family Health Program, Petrolina, Pernambuco, Brazil.

METHODS

63 hypertensive patients (30-79 years old; 70% female) were randomly allocated into IHT or control groups. IHT was performed three times per week (4 x 2 minutes at 30% of maximal voluntary contraction, one-minute rest between bouts, alternating the hands). Before and after the 12-week training period, office and ambulatory blood pressure and heart rate variability were obtained. The significance level was set at P < 0.05 (two-tailed testing) for all analyses.

RESULTS

IHT significantly decreased office systolic blood pressure (IHT: 129 ± 4 versus 121 ± 3 mmHg, P < 0.05; control: 126 ± 4 versus 126 ± 3 mmHg, P > 0.05), whereas there was no effect on diastolic blood pressure (IHT: 83 ± 3 versus 79 ± 2 mmHg, P > 0.05; control: 81 ± 3 versus 77 ± 3 mmHg, P > 0.05). Heart rate variability and ambulatory blood pressure were not altered by the interventions (P > 0.05 for all).

CONCLUSION

IHT reduced office systolic blood pressure in hypertensive patients attended within primary care. However, there were effects regarding diastolic blood pressure, ambulatory blood pressure or heart rate variability.

CLINICALTRIALS.GOV IDENTIFIER

NCT03216317.

The efficacy of 'static' training interventions for improving indices of cardiorespiratory fitness in premenopausal females

PURPOSE

Cardiovascular disease (CVD) is the leading cause of death worldwide. Many risk factors for CVD can be modified pharmacologically; however, uptake of medications is low, especially in asymptomatic people. Exercise is also effective at reducing CVD risk, but adoption is poor with time-commitment and cost cited as key reasons for this. Repeated remote ischaemic preconditioning (RIPC) and isometric handgrip (IHG) training are both inexpensive, time-efficient interventions which have shown some promise in reducing blood pressure (BP) and improving markers of cardiovascular health and fitness. However, few studies have investigated the effectiveness of these interventions in premenopausal women.

METHOD

Thirty healthy females were recruited to twelve supervised sessions of either RIPC or IHG over 4 weeks, or acted as non-intervention controls (CON). BP measurements, flow-mediated dilatation (FMD) and cardiopulmonary exercise tests (CPET) were performed at baseline and after the intervention period.

RESULTS

IHG and RIPC were both well-tolerated with 100% adherence to all sessions. A statistically significant reduction in both systolic (- 7.2 mmHg) and diastolic (- 6 mmHg) BP was demonstrated following IHG, with no change following RIPC. No statistically significant improvements were observed in FMD or CPET parameters in any group.

CONCLUSIONS

IHG is an inexpensive and well-tolerated intervention which may improve BP; a key risk factor for CVD. Conversely, our single arm RIPC protocol, despite being similarly well-tolerated, did not elicit improvements in any cardiorespiratory parameters in our chosen population.

Resting blood pressure reductions following handgrip exercise training and the impact of age and sex: a systematic review and narrative synthesis

BACKGROUND

The risk of developing cardiovascular disease can be directly correlated to one's resting blood pressure (BP), age, and biological sex. Resting BP may be successfully reduced using handgrip exercise training, although the impact of age and sex on training effectiveness has yet to be systematically evaluated. The objective of this systematic review is to determine this impact of age and sex on handgrip-induced changes to resting BP.

METHODS

Data sources included MEDLINE, Embase, Cochrane Reviews, CINAHL, SPORTDiscus, Web of Science, AMED, PubMed, and Scopus through May 2018. Eligibility criteria were those with prospective handgrip exercise training of ≥ 4 weeks with reported impact on resting systolic BP (SBP). Screening of articles, data extraction, and quality appraisal were completed in duplicate. When necessary, the corresponding authors were contacted to provide segregated data based on age (younger, 18-54 years; aged, > 55 years) and sex (men, women) categories. SBP was primarily explored with numerous secondary outcomes of interest summarized as a narrative synthesis.

RESULTS

After screening 1789 articles, 26 full texts were reviewed. Eight studies reported data in a way that facilitated age and sex comparisons of primary outcomes, while 7 of 18 studies reporting pooled data (men and women) provided segregated results. Research spans 1992-2018 and represents 466 participants; at least 43.1% of whom are women. Although weighted mean differences reveal that handgrip training-induced SBP reductions are similar when merely comparing sexes (women; - 5.6 mmHg, men; - 4.4 mmHg) or ages (younger; - 5.7 mmHg, aged; - 4.4 mmHg), when the impact of sex and age is simultaneously evaluated, aged women experience the largest reduction in SBP (- 6.5 mmHg). Many factors were explored for their impact on resting BP reductions and have been summarized in the corresponding narrative synthesis.

CONCLUSIONS

Handgrip exercise is an effective modality for resting BP reduction resulting in clinically significant reductions for men and women of all ages.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015019792.

Characterizing and Comparing Acute Responses of Blood Pressure, Heart Rate, and Forearm Blood Flow to 2 Handgrip Protocols

PURPOSE

Growing evidence supports handgrip exercise training for reducing resting blood pressure (BP), with inconsistent exercise protocols reported throughout the literature. To verify safety of such protocols, real-time cardiovascular responses must be assessed. Consequently, this research sought to evaluate the acute impact of dissimilar handgrip protocols on the cardiovascular responses of BP, heart rate (HR), and forearm blood flow.

METHODS

Using a randomized intraindividual crossover design, 20 post-menopausal women completed 2 distinct handgrip protocols compared with a nonexercise control: 4 × 2-min sustained grips at 30% moderate intensity with 1-min rest between sets (ZONA), and 32 × 5-sec intermittent grips at maximal intensity with 5-sec rest between sets (MINT). Cardiovascular responses were measured throughout exercise and post-exercise recovery.

RESULTS

Compared to ZONA, the MINT protocol required less time and less exercise effort, yet caused greater average BP perturbations (systolic, MINT: 16.9 ± 12.9 mm Hg, ZONA: 7.9 ± 11.6 mm Hg; diastolic, MINT: 8.7 ± 7.2 mm Hg, ZONA: 4.5 ± 4.9 mm Hg) (P < .05), with peak BP changes far below published safety guidelines. Average HR responses were similarly elevated between protocols (MINT: 5.4 ± 4.9 beats/min, ZONA: 3.4 ± 3.6 beats/min). Post-exercise recovery of BP and HR occurred swiftly following MINT while remaining elevated following ZONA.

CONCLUSIONS

Handgrip exercise protocols with distinct design features (ie, grip intensity, grip strategy, and exercise duration) cause dissimilar acute cardiovascular responses. Careful and controlled attention should be directed toward determining how such acute dissimilarities influence corresponding training outcomes. Given the confirmed safety of acute BP perturbations, future researchers can have confidence in prescribing even the high-intensity MINT protocol for at-home, unsupervised activity.

The safety of isometric exercise: Rethinking the exercise prescription paradigm for those with stage 1 hypertension

Few studies have investigated the relative safety of prescribing isometric exercise (IE) to reduce resting blood pressure (BP). This study aimed to ascertain the safety of the hemodynamic response during an IE wall squat protocol.Twenty-six hypertensive (BP of 120-139 mm Hg systolic and/or 80-90 mm Hg diastolic) males (45 ± 8 years; 1.78 ± 0.07 m; 89.7 ± 12.3 kg; mean ± SD), visited the laboratory on 2 separate occasions. Heart rate (HR) and BP were measured at rest and continuously throughout exercise. In visit 1, participants completed a continuous incremental isometric wall squat exercise test, starting at 135° of knee flexion, decreasing by 10° every 2 minutes until 95° (final stage). Exercise was terminated upon completion of the test or volitional fatigue. The relationship between knee joint angle and mean HR was used to calculate the participant-specific knee joint angle required to elicit a target HR of 95% HRpeak. This angle was used to determine exercise intensity for a wall squat training session consisting of 4 × 2 minute bouts (visit 2).Systolic BPs during the exercise test and training were 173 ± 21 mm Hg and 171 ± 19 mm Hg, respectively, (P > .05) and were positively related (r = 0.73, P < .05) with ratio limits of agreement (LoA) of 0.995 ×/÷ 1.077. Diastolic BPs were 116 ± 14 mm Hg and 113 ± 11 mm Hg, respectively, (P > .05) and were positively related (r = 0.42, P < .05) with ratio LoA of 0.99 ×/÷ 1.107. No participant recorded a systolic BP > 250 mm Hg. Diastolic BP values > 115 mm Hg were recorded in 12 participants during the incremental test and 6 participants during the training session. Peak rate pressure product was 20681 ± 3911 mm Hg bpm during the IE test and was lower (18074 ± 3209 mm Hg bpm) during the IE session (P = .002). No adverse effects were reported.Based on the current ACSM guidelines for aerobic exercise termination, systolic BP does not reach the upper limit during IE in this population. Diastolic BP exceeds 115 mm Hg in some during the IE protocol, which may suggest the need to individualise IE training prescription in some with suboptimal BP control. Future research is required to ascertain if IE requires modified BP termination guidelines.

The Effects of Exercise Training on Brachial Artery Flow-Mediated Dilation: A Meta-analysis

PURPOSE

Flow-mediated dilation, a barometer of cardiovascular (CV) health, is reported to increase with exercise training (ET); however, the potential moderating factors of ET are not clear to date. The purpose of this study was to determine the effect of ET assessed by brachial artery flow-mediated dilation (BAFMD).

METHODS

Authors searched PubMed between January 1999 and December 2013, bibliographies, and reviews to identify studies examining ET and BAFMD. Two independent reviewers extracted quality, descriptive, exercise, and outcome data of eligible studies. Data were presented as weighted effect sizes (ESs) and 95% confidence limits.

RESULTS

Analysis included 66 studies reporting BAFMD data (1865 ET and 635 control subjects). Overall, ET had significant improvements in BAFMD compared with controls (P < .0001). Exercise training at higher ET intensities resulted in a greater increase in BAFMD (9.29; 95% CI, 5.09-13.47) than lower ET intensities (3.63; 95% CI, -0.56 to 7.83) or control (-0.42; 95% CI, -2.06 to 1.21). Subjects whose ET duration was ≥150 min/wk (11.33; 95% CI, 7.15-15.51) had a significant improvement in BAFMD compared with those with <150 min/wk (4.79; 95% CI, 3.08-6.51) or control (-0.30; 95% CI, -1.99 to 1.39). Age (P = .11) and baseline artery diameter (P = .31) did not modify the BAFMD response to ET.

CONCLUSION

Exercise training contributes to a significant increase in BAFMD. These results provide indirect evidence that ET alters a well-known factor associated with the primary and secondary prevention of CV diseases. Exercise training interventions, including greater intensity and duration, may optimize the increase in BAFMD.

Isometric Handgrip as an Adjunct for Blood Pressure Control: a Primer for Clinicians

Considered a global health crisis by the World Health Organization, hypertension (HTN) is the leading risk factor for death and disability. The majority of treated patients do not attain evidence-based clinical targets, which increases the risk of potentially fatal complications. HTN is the most common chronic condition seen in primary care; thus, implementing therapies that lower and maintain BP to within-target ranges is of tremendous public health importance. Isometric handgrip (IHG) training is a simple intervention endorsed by the American Heart Association as a potential adjuvant BP-lowering treatment. With larger reductions noted in HTN patients, IHG training may be especially beneficial for those who (a) have difficulties continuing or increasing drug-based treatment; (b) are unable to attain BP control despite optimal treatment; (c) have pre-HTN or low-risk stage I mild HTN; and (d) wish to avoid medications or have less pill burden. IHG training is not routinely prescribed in clinical practice. To shift this paradigm, we focus on (1) the challenges of current HTN management strategies; (2) the effect of IHG training; (3) IHG prescription; (4) characterizing the population for whom it works best; (5) clinical relevance; and (6) important next steps to foster broader implementation by clinical practitioners.

Reductions in Resting Blood Pressure in Young Adults When Isometric Exercise Is Performed Whilst Walking

Aerobic and isometric training have been shown to reduce resting blood pressure, but simultaneous aerobic and isometric training have not been studied. The purpose of this study was to compare the changes in resting systolic (SBP), diastolic (DBP), and mean arterial blood pressure (MAP) after 6 weeks of either (i) simultaneous walking and isometric handgrip exercise (WHG), (ii) walking (WLK), (iii) isometric handgrip exercise (IHG), or control (CON). Forty-eight healthy sedentary participants (age 20.7 ± 1.7 yrs, mass 67.2 ± 10.2 kg, height 176.7 ± 1.2 cm, male n = 26, and female n = 22) were randomly allocated, to one of four groups (n = 12 in each). Training was performed 4 × week-1 and involved either treadmill walking for 30 minutes (WLK), handgrip exercise 3 × 10 s at 20% MVC (IHG), or both performed simultaneously (WHG). Resting SBP, DBP, and MAP were recorded at rest, before and after the 6-week study period. Reductions in resting blood pressure were significantly greater in the simultaneous walking and handgrip group than any other group. These results show that simultaneous walking and handgrip training may have summative effects on reductions in resting blood pressure.

Home-based isometric exercise training induced reductions resting blood pressure

PURPOSE

Isometric exercise training (IET) reduces resting blood pressure (BP). Most previous protocols impose exercise barriers which undermine its effectiveness as a potential physical therapy for altering BP. An inexpensive, home-based programme would promote IET as a valuable tool in the fight against hypertension. The aims of this study were: (a) to investigate whether home-based wall squat training could successfully reduce resting BP and (b) to explore the physiological variables that might mediate a change in resting BP.

METHODS

Twenty-eight healthy normotensive males were randomly assigned to a control and a 4 week home-based IET intervention using a crossover design with a 4 week 'washout' period in-between. Wall squat training was completed 3 × weekly over 4 weeks with 48 h between sessions. Each session comprised 4 × 2 min bouts of wall squat exercise performed at a participant-specific knee joint angle relative to a target HR of 95% HR_peak, with 2 min rest between bouts. Resting heart rate, BP, cardiac output, total peripheral resistance, and stroke volume were taken at baseline and post each condition.

RESULTS

Resting BP (systolic -4 ± 5, diastolic -3 ± 3 and mean arterial -3 ± 3 mmHg), cardiac output (-0.54 ± 0.66 L min^-1) and heart rate (-5 ± 7 beats min^-1) were all reduced following IET, with no change in total peripheral resistance or stroke volume compared to the control.

CONCLUSION

These findings suggest that the wall squat provides an effective method for reducing resting BP in the home resulting primarily from a reduction in resting heart rate.

Clinically meaningful blood pressure reductions with low intensity isometric handgrip exercise. A randomized trial

There exists no examination of what is the minimum anti-hypertensive threshold intensity for isometric exercise training. Twenty two normotensive participants were randomly assigned to training intensities at either 5 % or 10 % of their maximal contraction. Twenty participants completed the study. Clinical meaningful, but not statistically significant, reductions in systolic blood pressure were observed in both 5 % and 10 % groups -4.04 mm Hg (95 % CI -8.67 to +0.59, p=0.08) and -5.62 mm Hg (95 % CI -11.5 to +0.29, p=0.06) respectively after 6 weeks training. No diastolic blood pressure reductions were observed in either 5 % -0.97 mm Hg (95 % CI -2.56 to +0.62, p=0.20) or 10 % MVC +1.8 mm Hg (95 % CI -1.29 to +4.89, p=0.22) groups respectively after training. In those unable to complete isometric exercise at the traditional 30 % intensity, our results suggest there is no difference between 5 and 10 % groups and based on the principle of regression to the mean, this could mean both interventions induce a similar placebo-effect.

Low intensity resistance exercise training with blood flow restriction: insight into cardiovascular function, and skeletal muscle hypertrophy in humans

Attenuated functional exercise capacity in elderly and diseased populations is a common problem, and stems primarily from physical inactivity. Decreased function and exercise capacity can be restored by maintaining muscular strength and mass, which are key factors in an independent and healthy life. Resistance exercise has been used to prevent muscle loss and improve muscular strength and mass. However, the intensities necessary for traditional resistance training to increase muscular strength and mass may be contraindicated for some at risk populations, such as diseased populations and the elderly. Therefore, an alternative exercise modality is required. Recently, blood flow restriction (BFR) with low intensity resistance exercise (LIRE) has been used for such special populations to improve their function and exercise capacity. Although BFR+LIRE has been intensively studied for a decade, a comprehensive review detailing the effects of BFR+LIRE on both skeletal muscle and vascular function is not available. Therefore, the purpose of this review is to discuss previous studies documenting the effects of BFR+LIRE on hormonal and transcriptional factors in muscle hypertrophy and vascular function, including changes in hemodynamics, and endothelial function.

Evidence for the role of isometric exercise training in reducing blood pressure: potential mechanisms and future directions

Hypertension, or the chronic elevation in resting arterial blood pressure (BP), is a significant risk factor for cardiovascular disease and estimated to affect ~1 billion adults worldwide. The goals of treatment are to lower BP through lifestyle modifications (smoking cessation, weight loss, exercise training, healthy eating and reduced sodium intake), and if not solely effective, the addition of antihypertensive medications. In particular, increased physical exercise and decreased sedentarism are important strategies in the prevention and management of hypertension. Current guidelines recommend both aerobic and dynamic resistance exercise training modalities to reduce BP. Mounting prospective evidence suggests that isometric exercise training in normotensive and hypertensive (medicated and non-medicated) cohorts of young and old participants may produce similar, if not greater, reductions in BP, with meta-analyses reporting mean reductions of between 10 and 13 mmHg systolic, and 6 and 8 mmHg diastolic. Isometric exercise training protocols typically consist of four sets of 2-min handgrip or leg contractions sustained at 20-50 % of maximal voluntary contraction, with each set separated by a rest period of 1-4 min. Training is usually completed three to five times per week for 4-10 weeks. Although the mechanisms responsible for these adaptations remain to be fully clarified, improvements in conduit and resistance vessel endothelium-dependent dilation, oxidative stress, and autonomic regulation of heart rate and BP have been reported. The clinical significance of isometric exercise training, as a time-efficient and effective training modality to reduce BP, warrants further study. This evidence-based review aims to summarize the current state of knowledge regarding the effects of isometric exercise training on resting BP.

Intensity-dependent reductions in resting blood pressure following short-term isometric exercise training

To reduce resting blood pressure, a minimum isometric exercise training (IET) intensity has been suggested, but this is not known for short-term IET programmes. We therefore compared the effects of moderate- and low-intensity IET programmes on resting blood pressure. Forty normotensive participants (22.3 ± 3.4 years; 69.5 ± 15.5 kg; 170.2 ± 8.7 cm) were randomly assigned to groups of differing training intensities [20%EMGpeak (~23%MVC, maximum voluntary contraction, or 30%EMGpeak (~34%MVC)] or control group; 3 weeks of IET at 30%EMGpeak resulted in significant reductions in resting mean arterial pressure (e.g. -3.9 ± 1.0 mmHg, P < 0.001), whereas 20%EMGpeak did not (-2.3 ± 2.9 mmHg; P > 0.05). Moreover, after pooling all female versus male participants, IET induced a 6.9-mmHg reduction in systolic blood pressure in female participants, but only a 1.5-mmHg reduction in systolic blood pressure in male participants, although the difference was not significant. An IET intensity between 20%EMGpeak and 30%EMGpeak is sufficient to elicit significant resting blood pressure reductions in a short-term training period (3 weeks). In addition, sexual dimorphism may exist in the magnitude of reductions, but further work is required to confirm this possibility, which could be important in understanding the mechanisms responsible.

Isometric exercise training for blood pressure management: a systematic review and meta-analysis

OBJECTIVE

To conduct a systematic review and meta-analysis quantifying the effects of isometric resistance training on the change in systolic blood pressure(SBP), diastolic blood pressure (DBP), and mean arterial pressure in subclinical populations and to examine whether the magnitude of change in SBP and DBP was different with respect to blood pressure classification.

PATIENTS AND METHODS

We conducted a systematic review and meta-analysis of randomized controlled trials lasting 4 or more weeks that investigated the effects of isometric exercise on blood pressure in healthy adults (aged ≥18 years) and were published in a peer-reviewed journal. PubMed, CINAHL, and the Cochrane Central Register of Controlled Trials were searched for trials reported between January 1, 1966, and July 31, 2013. We included 9 randomized trials, 6 of which studied normotensive participants and 3 that studied hypertensive patients, that included a total of 223 participants (127 who underwent exercise training and 96 controls).

RESULTS

The following reductions were observed after isometric exercise training: SBP-mean difference (MD), -6.77 mm Hg (95% CI, -7.93 to -5.62 mm Hg; P<.001); DBP-MD, -3.96 mm Hg (95% CI, -4.80 to -3.12 mm Hg; P<.001); and mean arterial pressure-MD, -3.94 mm Hg (95% CI, -4.73 to -3.16 mm Hg; P<.001). A slight reduction in resting heart rate was also observed (MD, -0.79 beats/min; 95% CI, -1.23 to -0.36 beats/min; P=.003).

CONCLUSION

Isometric resistance training lowers SBP, DBP, and mean arterial pressure. The magnitude of effect is larger than that previously reported in dynamic aerobic or resistance training. Our data suggest that this form of training has the potential to produce significant and clinically meaningful blood pressure reductions and could serve as an adjunctive exercise modality.

The effects of isometric wall squat exercise on heart rate and blood pressure in a normotensive population

The isometric wall squat could be utilised in home-based training aimed at reducing resting blood pressure, but first its suitability must be established. The aim of this study was to determine a method of adjusting wall squat intensity and explore the cardiovascular responses. Twenty-three participants performed one 2 minute wall squat on 15 separate occasions. During the first ten visits, ten different knee joint angles were randomly completed from 135° to 90° in 5° increments; five random angles were repeated in subsequent visits. Heart rate and blood pressure (systolic, diastolic and mean arterial pressure) were measured. The heart rate and blood pressure parameters produced significant inverse relationships with joint angle (r at least -0.80; P < 0.05), demonstrating that wall squat intensity can be adjusted by manipulating knee joint angle. Furthermore, the wall squat elicited similar cardiovascular responses to other isometric exercise modes that have reduced resting blood pressure (135° heart rate: 76 ± 10 beats ∙ min(-1); systolic: 134 ± 14 mmHg; diastolic: 76 ± 6 mmHg and 90° heart rate: 119 ± 20 beats ∙ min(-1); systolic: 196 ± 18 mmHg; diastolic: 112 ± 13 mmHg). The wall squat may have a useful role to play in isometric training aimed at reducing resting blood pressure.

Isometric handgrip does not elicit cardiovascular overload or post-exercise hypotension in hypertensive older women

BACKGROUND

Arterial hypertension is a serious health problem affecting mainly the elderly population. Recent studies have considered both aerobic and resistance exercises as a non-pharmacological aid for arterial hypertension treatment. However, the cardiovascular responses of the elderly to isometric resistance exercise (eg, isometric handgrip [IHG]) have not yet been documented.

OBJECTIVE

The purpose of this study was to investigate cardiovascular responses to different intensities of isometric exercise, as well as the occurrence of post-isometric exercise hypotension in hypertensive elderly people under antihypertensive medication treatment.

PATIENTS AND METHODS

Twelve women volunteered to participate in the study after a maximal voluntary contraction test (MVC) and standardization of the intervention workload consisting of two sessions of IHG exercise performed in four sets of five contractions of a 10-second duration. Sessions were performed both at 30% of the MVC and 50% of the MVC, using a unilateral IHG protocol. Both intensities were compared with a control session without exercise. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) at rest (R), during peak exercise (PE), and after 5, 10, 15, 30, 45, and 60 minutes of post-exercise recovery were evaluated.

RESULTS

No significant changes were observed after isometric exercise corresponding to 30% MVC for either SBP (R: 121 ± 10; PE: 127 ± 14; 5 min: 125 ± 13; 10 min: 123 ± 12; 15 min: 122 ± 11; 30 min: 124 ± 11; 45 min: 124 ± 10; 60 min: 121 ± 10 mmHg) or DBP (R: 74 ± 9; PE: 76 ± 6; 5 min: 74 ± 5; 10 min: 72 ± 8; 15 min: 72 ± 5; 30 min: 72 ± 8; 45 min: 73 ± 6; 60 min: 75 ± 7 mmHg). Similarly, the 50% MVC did not promote post-isometric exercise hypotension for either SBP (R: 120 ± 7; PE: 125 ± 11; 5 min: 120 ± 9; 10 min: 122 ± 9; 15 min: 121 ± 11; 30 min: 121 ± 9; 45 min: 121 ± 9; 60 min: 120 ± 7 mmHg) or DBP (R: 72 ± 8; PE: 78 ± 7; 5 min: 72 ± 7; 10 min: 72 ± 8; 15 min: 71 ± 7; 30 min: 72 ± 8; 45 min: 75 ± 10; 60 min: 75 ± 7 mmHg).

CONCLUSION

Our data reveal that cardiovascular overload or post-exercise hypotension did not occur in elderly women with controlled hypertension when they undertook an IHG session. Thus this type of resistance exercise, with mild to moderate intensity, with short time of contraction appears to be safe for this population.

Effects of isometric handgrip training dose on resting blood pressure and resistance vessel endothelial function in normotensive women

Isometric handgrip (IHG) training lowers resting blood pressure (BP) in both hypertensives and normotensives, yet the effect of training dose on the magnitude of reduction and the mechanisms associated with the hypotensive response are elusive. We investigated, in normotensive women, the effects of two different doses of IHG training on resting BP, and explored improved resistance vessel endothelial function and heart rate variability (HRV) as potential mechanisms of BP reduction. Resting BP, HRV, and resistance vessel endothelial function (venous strain-gauge plethysmography with reactive hyperemia) were assessed in 32 women before and after 4 and 8 weeks of 3×/week (n = 12) or 5×/week (n = 11) IHG training (four, 2-min unilateral contractions at 30 % maximal voluntary contraction), or 0×/week control (n = 9). IHG training decreased systolic BP in the 3×/week (94 ± 6 to 91 ± 6 to 88 ± 5 mmHg, pre- to mid- to post-training; P < 0.01) and 5×/week (97 ± 11 to 90 ± 9 to 91 ± 9 mmHg, P < 0.01) groups, concomitant with increased forearm reactive hyperemic blood flow (26 ± 7 to 30 ± 8 to 36 ± 9 mL/min/100 mL tissue, P < 0.01; and 26 ± 7 to 29 ± 7 to 38 ± 13 mL/min/100 mL tissue, P < 0.01, respectively), yet both remained unchanged in the control group. No changes were observed in diastolic BP, mean arterial BP, or any indices of HRV in any group (all P > 0.05). In conclusion, IHG training lowers resting systolic BP and improves resistance vessel endothelial function independent of training dose in normotensive women.

Blood flow restricted exercise and vascular function

It is established that regular aerobic training improves vascular function, for example, endothelium-dependent vasodilatation and arterial stiffness or compliance and thereby constitutes a preventative measure against cardiovascular disease. In contrast, high-intensity resistance training impairs vascular function, while the influence of moderate-intensity resistance training on vascular function is still controversial. However, aerobic training is insufficient to inhibit loss in muscular strength with advancing age; thus, resistance training is recommended to prevent sarcopenia. Recently, several lines of study have provided compelling data showing that exercise and training with blood flow restriction (BFR) leads to muscle hypertrophy and strength increase. As such, BFR training might be a novel means of overcoming the contradiction between aerobic and high-intensity resistance training. Although it is not enough evidence to obtain consensus about impact of BFR training on vascular function, available evidences suggested that BFR training did not change coagulation factors and arterial compliance though with inconsistence results in endothelial function. This paper is a review of the literature on the impact of BFR exercise and training on vascular function, such as endothelial function, arterial compliance, or other potential factors in comparison with those of aerobic and resistance training.

Effects of the intensity of leg isometric training on the vasculature of trained and untrained limbs and resting blood pressure in middle-aged men

The purpose of this study was to establish whether changes in resting blood pressure and the vasculature of trained and untrained limbs are dependent on training intensity, following isometric-leg training. Thirty middle-aged males undertook an 8 week training programme (4 × 2 min bilateral-leg isometric contractions 3 times per week). Two groups trained at either high (HI; 14%MVC) or low (LO; 8%MVC) intensity a third group (CON) acted as controls. All parameters were measured at baseline, 4-weeks and post-training. Resting SBP (−10.8 ± 7.9 mmHg), MAP (−4.7 ± 6.8 mmHg) and HR (−4.8 ± 5.9 b·min⁻¹) fell significantly in the HI group post-training with concomitant significant increases in resting femoral mean artery diameter (FMAD; 1.0 ± 0.4 mm), femoral mean blood velocity (FMBV; 0.68 ± 0.83 cm·s⁻¹), resting femoral artery blood flow (FABF; 82.06 ± 31.92 ml·min⁻¹) and resting femoral vascular conductance (FVC, 45%). No significant changes occurred in any brachial artery measure nor in any parameters measured in the LO or CON groups. These findings show that training-induced reductions in resting blood pressure after isometric-leg training in healthy middle-aged men are associated with concomitant adaptations in the local vasculature, that appear to be dependent on training intensity and take place in the later stages of training.

The association of arterial shear and flow-mediated dilation in diabetes

While adjusting flow-mediated dilation (FMD), a measure of vascular function, for shear rate may be important when evaluating endothelial-dependent vasodilation, the relationship of FMD with shear rate in study populations with cardiovascular risk factors is unclear. We aimed to investigate the association of four measures of shear rate (peak shear rate (SR(peak)) and shear rate area under the curve through 30 seconds (SR(AUC 0-30)), 60 seconds (SR(AUC 0-60)), and time to peak dilation (SR(AUC 0-ttp))) with FMD in 50 study subjects with type 2 diabetes and mild hypertension undergoing baseline FMD testing for an exercise intervention trial. Associations among measures of shear rate and FMD were evaluated using Pearson's correlations and R(2). The four measures of shear rate were highly correlated within subjects, with Pearson's correlations ranging from 0.783 (p < 0.001) to 0.972 (p < 0.001). FMD was associated with each measure of shear rate, having a correlation of 0.576 (p < 0.001) with SR(AUC 0-30), 0.529 (p < 0.001) with SR(AUC 0-60), and 0.512 (p < 0.001) with SR(peak). Nine of 50 subjects (18%) did not dilate following the shear stimulus. Among the 41 responders, FMD had a correlation of 0.517 (p < 0.001) with SR(AUC 0-ttp) and similar correlations to those found in the full sample for SR(AUC 0-30), SR(AUC 0-60), and SR(peak). In conclusion, shear rate appears to explain up to a third of between-person variability in FMD response and our results support the reporting of shear rate and FMD with and without adjustment for shear rate in similar clinical populations with CVD risk factors.

Exercise and arterial adaptation in humans: uncoupling localized and systemic effects

Previous studies have established effects of exercise training on arterial wall thickness, remodeling, and function in humans, but the extent to which these changes are locally or systemically mediated is unclear. We examined the brachial arteries of the dominant (D) and nondominant (ND) upper limbs of elite racquet sportsmen and compared them to those of matched healthy inactive controls. Carotid and superficial femoral artery responses were also assessed in both groups. High-resolution duplex ultrasound was used to examine resting diameter, wall thickness, peak diameter, and blood flow. We found larger resting arterial diameter in the preferred arm of the athletes (4.9 ± 0.5 mm) relative to their nonpreferred arm (4.3 ± 0.4 mm, P < 0.05) and both arms of control subjects (D: 4.1 ± 0.4 mm; ND: 4.0 ± 0.4, P < 0.05). Similar limb-specific differences were also evident in brachial artery dilator capacity (5.5 ± 0.5 vs. 4.8 ± 0.4, 4.8 ± 0.6, and 4.8 ± 0.6 mm, respectively; P < 0.05) following glyceryl trinitrate administration and peak blood flow (1,118 ± 326 vs. 732 ± 320, 737 ± 219, and 698 ± 174 ml/min, respectively; P < 0.05) following ischemic handgrip exercise. In contrast, athletes demonstrated consistently lower wall thickness in carotid (509 ± 55 μm), brachial (D: 239 ± 100 μm; ND: 234 ± 133 μm), and femoral (D: 479 ± 38 μm; ND: 479 ± 42 μm) arteries compared with control subjects (carotid: 618 ± 74 μm; brachial D: 516 ± 100 μm; ND: 539 ± 129 μm; femoral D: 634 ± 155 μm; ND: 589 ± 112 μm; all P < 0.05 vs. athletes), with no differences between the limbs of either group. These data suggest that localized effects of exercise are evident in the remodeling of arterial size, whereas arterial wall thickness appears to be affected by systemic factors.

The impact of exercise training on the diameter dilator response to forearm ischaemia in healthy men

AIM

Recent studies found differences between groups in the rate of diameter increase following the flow-mediated dilation (FMD). Whilst exercise training alters the magnitude of the FMD, little is known about the impact of exercise training on the rate of diameter increase. The aim of this study is to examine post-cuff deflation changes in brachial artery diameter following 5 min forearm ischaemia every 2 weeks across 8-weeks of a handgrip exercise training regimen.

METHODS

Post-deflation changes in brachial artery diameter following 5-min of ischaemia were examined before, after and every 2-weeks across an 8-week handgrip training programme in healthy young men (n = 11) using echo-Doppler.

RESULTS

The magnitude of dilation increased at week 2-4-6, but returned towards baseline values at week 8 (anova: P = 8.001). The time-to-peak diameter (42 ± 15s) demonstrated a significant prolongation at week 4 (77 ± 32s), but returned towards baseline values at weeks 6 and 8 (anova: P < 0.001). The rate of diameter increase did not differ across the intervention.

CONCLUSION

Exercise training in healthy subjects is initially characterized by a larger dilation. Since the rate of dilation did not change, a longer time-to-peak dilation was necessary to achieve the increase in magnitude of dilation. As exercise training continues, the timing and magnitude of the peak diameter response returns to near baseline levels.

Arterial prehabilitation: can exercise induce changes in artery size and function that decrease complications of catheterization?

Coronary angiography and angioplasty are common invasive procedures in cardiovascular medicine, which involve placement of a sheath inside peripheral conduit arteries. Sheath placement and catheterization can be associated with arterial thrombosis, spasm and occlusion. In this paper we review the literature pertaining to the possible benefits of arterial 'prehabilitation'--the concept that interventions aimed at enhancing arterial function and size (i.e. remodelling) should be undertaken prior to cardiac catheterization or artery harvest during bypass graft surgery. The incidence of artery spasm, occlusion and damage is lower in larger arteries with preserved endothelial function. We conclude that the beneficial effects of exercise training on both artery size and function, which are particularly evident in individuals who possess cardiovascular diseases or risk factors, infer that exercise training may reduce complication rates following catheterization and enhance the success of arteries harvested as bypass grafts. Future research efforts should focus directly on examination of the 'prehabilitation' hypothesis and the efficacy of different interventions aimed at reducing clinical complications of common interventional procedures.

Impact of inactivity and exercise on the vasculature in humans

The effects of inactivity and exercise training on established and novel cardiovascular risk factors are relatively modest and do not account for the impact of inactivity and exercise on vascular risk. We examine evidence that inactivity and exercise have direct effects on both vasculature function and structure in humans. Physical deconditioning is associated with enhanced vasoconstrictor tone and has profound and rapid effects on arterial remodelling in both large and smaller arteries. Evidence for an effect of deconditioning on vasodilator function is less consistent. Studies of the impact of exercise training suggest that both functional and structural remodelling adaptations occur and that the magnitude and time-course of these changes depends upon training duration and intensity and the vessel beds involved. Inactivity and exercise have direct "vascular deconditioning and conditioning" effects which likely modify cardiovascular risk.

Shear stress mediates endothelial adaptations to exercise training in humans

Although episodic changes in shear stress have been proposed as the mechanism responsible for the effects of exercise training on the vasculature, this hypothesis has not been directly addressed in humans. We examined brachial artery flow-mediated dilation, an index of NO-mediated endothelial function, in healthy men in response to an acute bout of handgrip exercise and across an 8-week period of bilateral handgrip training. Shear stress responses were attenuated in one arm by cuff inflation to 60 mm Hg. Similar increases were observed in grip strength and forearm volume and girth in both limbs. Acute bouts of handgrip exercise increased shear rate (P<0.005) and flow-mediated dilation percentage (P<0.05) in the uncuffed limb, whereas no changes were evident in the cuffed arm. Handgrip training increased flow-mediated dilation percentage in the noncuffed limb at weeks 2, 4, and 6 (P<0.001), whereas no changes were observed in the cuffed arm. Brachial artery peak reactive hyperemia, an index of resistance artery remodeling, progressively increased with training in the noncuffed limb (P<0.001 and 0.004); no changes were evident in the cuffed arm. Neither acute nor chronic shear manipulation during exercise influenced endothelium-independent glyceryl trinitrate responses. These results demonstrate that exercise-induced changes in shear provide the principal physiological stimulus to adaptation in flow-mediated endothelial function and vascular remodeling in response to exercise training in healthy humans.

Increase in calf post-occlusive blood flow and strength following short-term resistance exercise training with blood flow restriction in young women

The response of calf muscle strength, resting (R (bf)) and post-occlusive (PO(bf)) blood flow were investigated following 4 weeks resistance training with and without blood flow restriction in a matched leg design. Sixteen untrained females performed unilateral plantar-flexion low-load resistance training (LLRT) at either 25% (n = 8) or 50% (n = 8) one-repetition maximum (1 RM). One limb was trained with unrestricted blood flow whilst in the other limb blood flow was restricted with the use of a pressure applied cuff above the knee (110 mmHg). Regardless of the training load, peak PO(bf), measured using venous occlusion plethysmography increased when LLRT was performed with blood flow restriction compared to no change following LLRT with unrestricted blood flow. A significant increase (P < 0.05) in the area under the blood time-flow curve was also observed following LLRT with blood flow restriction when compared LLRT with unrestricted blood flow. No changes were observed in R (bf) between groups following training. Maximal dynamic strength (1 RM), maximal voluntary contraction and isokinetic strength at 0.52 and 1.05 rad s(-1) also increased (P < 0.05) by a greater extent following resistance training with blood flow restriction. Moreover, 1 RM increased to a greater extent following training at 50% 1 RM compared to 25% 1 RM. These results suggest that 4 weeks LLRT with blood flow restriction provides a greater stimulus to increase peak PO(bf) as well as strength parameters than LLRT with unrestricted blood flow.

The hypotensive effects of isometric handgrip training using an inexpensive spring handgrip training device

PURPOSE

Research has demonstrated the efficacy of isometric handgrip (IHG) training to attenuate resting blood pressure. These studies have relied on the use of programmable digital handgrips for training. This study aimed to determine the effectiveness of simple, inexpensive spring-loaded handgrip devices in producing hypotensive effects.

METHODS

The study was a randomized controlled trial of 49 normotensive participants (66.4 +/- 0.9 years; 57% women). Participants in the exercise group (n = 25) trained and had blood pressure measured twice weekly for 8 weeks. Control participants (n = 24) completed weekly blood pressure measurements. Pre- and posttraining measurements were each assessed over 3 visits. Statistical analysis of the pre-post data involved analyses of variance and hierarchical linear modeling was used to examine changes over time.

RESULTS

Following 8 weeks, IHG participants demonstrated significant reductions in resting blood pressure. Systolic and diastolic blood pressures were reduced from 122 +/- 3 mm Hg to 112 +/- 3 mm Hg (P < .001) and from 70 +/- 1 mm Hg to 67 +/- 1 mm Hg (P < .05), respectively. Hierarchical linear modeling analysis also revealed a significant cross-level (ie, group / time) interaction, with an estimated reduction in systolic blood pressure of 5.4 mm Hg (P < .001) over the training period in the IHG group.

CONCLUSIONS

In agreement with previous studies, IHG training reduced resting arterial pressure following 8 weeks of training. Hypotensive effects linked to IHG training may be achieved using simple, inexpensive spring handgrip training devices and may provide a convenient and affordable therapeutic alternative or adjunctive therapy for lowering blood pressure.