Cardiovascular responses to light isometric and aerobic exercise in 21- and 59-year-old males

Optimization of the seat position for a personal vehicle equipped with a crankset: pilot study

The aim of the study was to optimize the seat for a personal vehicle equipped with a crankset mechanism, meant for everyday use. The inclination of the seat backrest was selected on the basis of theoretical considerations. Then dynamic tests were carried out on a group of young, healthy men in order to verify the ergonomic aspects of the seat position in relation to the crankset and determine the efficiency of the human-mechanism system with a load of 50 W. The data obtained from the dynamic tests were subject to statistical analysis. Research has shown that higher seat positions result in statistically higher efficiencies. In addition, a holistic analysis of the personal vehicle design problem shows that the upper position of the seat is also the best. The results of the research can be used to optimize personal vehicles using human force as a drive.

The autonomic and nociceptive response to acute exercise is impaired in people with knee osteoarthritis

Objectives

An acute bout of exercise typically leads to short term exercise induced hypoalgesia (EIH), but this response is more variable in many chronic pain populations, including knee osteoarthritis (OA) and fibromyalgia (FM). There is evidence of autonomic nervous system (ANS) dysfunction in some chronic pain populations that may contribute to impaired EIH, but this has not been investigated in people with knee OA. The aim of this study was to assess the acute effects of isometric exercise on the nociceptive and autonomic nervous systems in people with knee OA and FM, compared to pain-free controls.

Methods

A cross-sectional study was undertaken with 14 people with knee OA, 13 people with FM, and 15 pain free controls. Across two experimental sessions, baseline recordings and the response of the nociceptive and autonomic nervous systems to a 5-min submaximal isometric contraction of the quadriceps muscle was assessed. The nociceptive system was assessed using pressure pain thresholds at the knee and forearm. The ANS was assessed using high frequency heart rate variability, cardiac pre-ejection period, and electrodermal activity. Outcome measures were obtained before and during (ANS) or immediately after (nociceptive) the acute bout of exercise.

Results

Submaximal isometric exercise led to EIH in the control group. EIH was absent in both chronic pain groups. Both chronic pain groups showed lower vagal activity at rest. Furthermore, people with knee OA demonstrated reduced vagal withdrawal in response to acute isometric exercise compared to controls. Sympathetic reactivity was similar across groups.

Discussion

The findings of reduced tonic vagal activity and reduced autonomic modulation in response to isometric exercise raise the potential of a blunted ability to adapt to acute exercise stress and modulate nociception in people with knee OA. The impairment of EIH in knee OA may, in part, be due to ANS dysfunction.

Delay of cerebral autoregulation in traumatic brain injury patients

INTRODUCTION

Adequate cerebral perfusion prevents secondary insult after traumatic brain injury (TBI). Cerebral autoregulation (CAR) keeps cerebral blood flow (CBF) constant when arterial blood pressure (ABP) changes. Aim of the study was to evaluate the existence of delayed CAR in TBI patients and its possible association with outcome.

METHODS

We retrospectively analysed TBI patients. Flow velocity (FV) in middle cerebral artery, invasive intra-cranial pressure (ICP) and ABP were recorded. Cerebral perfusion pressure (CPP) was calculated as ABP - ICP. Mean flow index (Mx) > 0.3 defined altered CAR. Samples from patients with altered CAR were further analysed: FV signal was shifted backward relative to CPP; Mx was calculated after each shift (MxD). Mx > 0.3 plus MxD ≤ 0.3 defined delayed CAR. Favourable outcome (FO) at 6 months was defined as Glasgow Outcome Scale 4-5.

RESULTS

154 patients were included. GCS was 6 [4-9], ICP was 14 [9-20] mmHg. Data on 6 months outcome were available for 131 patients: 104/131 patients (79 %) were alive; GOS was 4 [3-5]; 70/131 (53 %) had FO. Mx was 0.07 [-0.19 to 0.28] overall. Mx was lower in patients with FO compared others (0.00 [-0.21 to 0.20] vs 0.17 [-0.12 to 0.37], p = 0.02). 118 (77 %) patients had intact CAR and 36 (23 %) patients had altered CAR; 23 patients - 15 % of the general cohort and 64 % of patients with altered CAR - had delayed CAR. Delay in the autoregulatory response was 2 [1-4] seconds. 80/98 (82 %) of patients with intact CAR survived, compared to 16/21 (76 %) with delayed and 8/12 (67 %) with altered CAR (p = 0.20). 80/98 (58 %) patients with intact, 10/21 (48 %) patients with delayed and 3/12 (25 %) patients with altered CAR had FO (p = 0.03).

CONCLUSION

A subgroup of TBI patients with delayed CAR was identified. Delayed CAR was associated with better neurological outcome than altered CAR.

Short-term water deprivation attenuates the exercise pressor reflex in older female adults

Older adults have reduced fluid intake and impaired body fluid and electrolyte regulation. Older female adults exhibit exaggerated exercise blood pressure (BP) responses, which is associated with an increased risk of adverse cardiovascular events. However, it is unclear if dysregulated body fluid homeostasis contributes to altered exercise BP responses in older female adults. We tested the hypothesis that short-term water deprivation (WD) increases exercise BP responses in older female adults. Fifteen female adults (eight young [25 ± 6 years] and seven older [65 ± 6 years]) completed two experimental conditions in random crossover fashion; a euhydration control condition and a stepwise reduction in water intake over three days concluding with a 16-hr WD period. During both trials, beat-to-beat BP (photoplethysmography) and heart rate (electrocardiogram) were continuously assessed during rest, handgrip exercise (30% MVC), and post-exercise ischemia (metaboreflex isolation). At screening, older compared to young female adults had greater systolic and diastolic BP (p ≤ .02). Accelerometer-assessed habitual physical activity was not different between groups (p = .65). Following WD, 24-hr urine flow rate decreased, whereas thirst, urine specific gravity, and plasma osmolality increased (condition: p < .05 for all), but these WD-induced changes were not different between age groups (interaction: p ≥ .31 for all). Resting systolic and diastolic BP values were higher in older compared to young adults (p < .01 for both), but were not different between experimental conditions (p ≥ .20). In contrast to our hypothesis, WD was associated with attenuated systolic BP responses during handgrip exercise (post hoc: p < .01) and post-exercise ischemia (post hoc: p = .03) in older, but not young, female adults. These data suggest that reduced water intake-induced challenges to body fluid homeostasis do not contribute to exaggerated exercise BP responses in post-menopausal female adults.

High cardiovascular reactivity and muscle strength attenuate hypotensive effects of isometric handgrip training in young women: A randomized controlled trial

OBJECTIVE

Isometric resistance training may reduce resting blood pressure (BP); however, the magnitude of this effect varies among individual subjects and few studies attempted to predict it. This study aimed to investigate the potential hypotensive effects of isometric training and their association with cardiovascular reactivity to acute isometric exercise and muscle strength in young women.

METHODS

In this randomized trial, twenty young women were randomly assigned to either the training (n = 10) or control (n = 10) group. Women from the training group performed unilateral isometric handgrip sessions for 8 weeks (4 × 2 min at 25% of maximal voluntary contraction [MVC]; 3 days/week). Cardiovascular reactivity to acute isometric exercise and MVC were measured at baseline. Resting BP was assessed during and after the intervention.

RESULTS

Resting systolic BP significantly lowered only in the training group. The change in resting systolic BP following an 8-week intervention was significantly associated with the systolic BP and diastolic BP reactivity to the acute exercise at baseline during set 3 and 4 (P <.05). The handgrip MVC was associated with changes in systolic BP (r = 0.79, P =.007), diastolic BP (r = 0.68, P =.032), and mean arterial pressure (r = 0.79, P =.006). These results indicated that high cardiovascular reactivity and strength attenuate the hypotensive effects following isometric training in young women.

CONCLUSIONS

The hypotensive effects following isometric training may be identified by BP reactivity to acute isometric exercise or handgrip strength in young women.

See red? Turn pale? Unveiling Emotions through Cardiovascular and Hemodynamic Changes

Cardiodynamic and hemodynamic reactions to emotion-eliciting film sequences were investigated. Thirty-two healthy subjects (12 women, 20 men) were randomly assigned to one of two groups. In the first group, anger was induced using selected scenes of the film “Ragtime.” In the second group, scenes of the film “The Shining” were chosen to elicit fear. A documentary film was used as a baseline stimulus in both groups. EKG, impedance cardiography, and blood pressure were continuously monitored. The two emotional conditions elicited significant differential changes in subjective ratings and cardiovascular indices. Fear was associated with decreased cardiac output, increased total peripheral resistance, and a reduction in stroke volume and myocardial contractility. Anger was associated with an increase of cardiac output and small changes in total peripheral resistance. These results support the hypothesis that discrete emotions such as fear and anger elicit differential patterns of physiological responses.

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.

Cardiovascular and hormonal responses to static handgrip in young and older healthy men

The purpose of this study was to investigate the effect of age on cardiovascular changes and plasma concentrations of adrenomedullin (ADM), catecholamines, endothelin-1 (ET-1) and plasma renin activity (PRA) in healthy men. A total of 15 young (21 ± 0.3 years) and 15 older (64 ± 0.7 years) healthy men performed two 3-min bouts of static handgrip at 30% of maximal voluntary contraction, alternately with each hand without any break between the bouts. During exercise heart rate (HR), blood pressure (BP), stroke volume (SV) and pre-ejection period (PEP) and left ventricle ejection time (LVET) were measured. Blood samples were taken before exercise, at the end of both exercise bouts and in the fifth minute of the recovery period. The handgrip-induced increases in HR and cardiac output were significantly smaller in older than in young men (p < 0.01). SV decreased only in older men (p < 0.001). There were no differences between groups in BP increases. The baseline plasma ADM and catecholamines were higher in older man compared to young subjects. Handgrip caused increases in plasma ADM, ET-1 and PRA only in older men (p < 0.05). The increases in plasma ADM correlated positively with those of noradrenaline (NA), PRA, ET-1 and LVET and negatively with changes in total peripheral resistance (TPR), SV, PEP and PEP/LVET ratio. The increases in plasma ET-1 correlated positively with those of NA, PRA, TPR, mean BP and SV. These results revealed that ADM, ET-1 and angiotensin II can contribute to maintain vascular tone during static exercise in older but not in younger men.

Blood pressure response to isometric exercise in patients with peripheral atherosclerotic disease

BACKGROUND

The purpose of this study was to compare the circulatory responses to isometric exercise in patients with peripheral atherosclerotic disease (PAD) with healthy controls.

METHODS

Eleven patients with diagnosed PAD, a control group of eleven healthy young adults, and a control group of eleven healthy age-matched adults participated. Blood pressure, heart rate, stroke volume, cardiac output, blood velocity in the brachial artery, acral skin perfusion was continuously recorded and total peripheral resistance calculated before, during and after 2 min of 40% maximum voluntary contraction of the forearm.

RESULTS

At rest we found a consistently higher level of mean arterial pressure (MAP) and systolic pressure (SP) in the elderly, both PAD patients and elderly controls, compared with the young controls. We found no significant difference in diastolic blood pressure. Two minutes isometric handgrip exercise induced a similar increase in MAP in all three groups (patients 32.6 (17.9) mm Hg [mean (SD)], young control group 25.3 (8.9) mm Hg, age-matched control group 36.1 (10.6) mm Hg). No significant differences were found in the other measured cardiovascular variables during isometric handgrip. Increased TPR is the main factor contributing to the increase in blood pressure in all three groups.

CONCLUSION

Our study indicates that the pressor response continues to be well regulated with age, also when the cardiovascular system is altered by marked atherosclerosis. The consequence is that both PAD patients and elderly controls reach higher SP values during isometric exercise due to higher SP baseline values.

Tai Chi Chih Acutely Decreases Sympathetic Nervous System Activity in Older Adults

BACKGROUND

Aging is associated with increases of sympathetic nervous system activation implicated in the onset of hypertension and cardiovascular disease. The purpose of this study was to examine whether the practice of Tai Chi Chih (TCC), a movement-based relaxation practice, would acutely promote decreases of sympathetic activity in elderly persons.

METHOD

The sample included two groups of older men and women (age > or = 60 years): TCC practitioners (n = 19) and TCC-naïve participants (n = 13). Participants were recruited after completing a 25-week randomized trial of TCC or health education. TCC practitioners performed TCC for 20 minutes, and TCC-naïve participants passively rested. Preejection period, blood pressure, and heart rate were measured before and after the task. A subsample (n = 8) returned for a second evaluation and performed videotape-guided stretching for 20 minutes to evaluate the effects of slow-moving physical activity on sympathetic activity.

RESULTS

Results showed that TCC performance significantly decreased sympathetic activity as indexed by preejection period (p =.01). In contrast, there was no change in preejection period following passive rest or slow-moving physical activity. Neither blood pressure nor heart rate changed after TCC performance.

DISCUSSION

This study is the first to our knowledge to assess the acute effects of TCC practice on sympathetic activity in older adults. TCC performance led to acute decreases in sympathetic activity, which could not be explained by physical activity alone. Further study is needed to determine whether the acute salutary effects of TCC on autonomic functioning are sustained with ongoing practice in older adults.

Delayed cerebrovascular autoregulatory response to ergometer exercise in normotensive elderly humans

BACKGROUND

Relatively little is known about physiological cerebrovascular haemodynamics during physical stress in elderly healthy individuals. The aim of this study was to determine the effect of ergometer stress on cerebrovascular haemodynamics in elderly healthy individuals in comparison with young healthy individuals, using non-invasive methods.

METHODS

Continuous middle cerebral artery blood flow velocity (CBFV; transcranial Doppler ultrasound), beat-to-beat blood pressure, heart rate and transcutaneous pCO(2) were measured in response to 3 min ergometer exercise stress in 18 elderly healthy subjects (mean age +/- SD 66.5 +/- 5.8 years) and 18 healthy young subjects (mean age +/- SD 29.4 +/- 4.7 years). Pulsatility index (PI) was used as a parameter for cerebrovascular resistance. The subjects were in a supine position with an elevated trunk and performed exercise by pedalling on an ergometer, generating 75-100 W. Statistical analysis was carried out using MANOVA, a general linear model with repeated measures.

RESULTS

In both groups, blood pressure increased significantly (p < 0.001) with time during exercise, with no significant differences between the groups or regarding interaction (time sequence/group factor). Heart rate increased significantly with time during exercise (p < 0.001) and was significantly more prominent (p = 0.002) and prolonged (p < 0.001) in the young group. pCO(2) did not differ with time or between the groups and with regard to interaction. Mean CBFV (MFV) increased significantly during time (p < 0.001). Between the groups, there was no significant difference (p = 0.836), but with regard to interaction (time sequence/group factor), there was a significant delay in MFV increase in the group of young subjects (p = 0.002). The PI, a measure of cerebrovascular resistance, increased significantly with time without significant differences between the groups (p = 0.061), but was significantly delayed in the elderly regarding the interaction time sequence/group factor (p < 0.001).

CONCLUSION

The cerebrovascular changes during ergometer exercise may reflect the combined activation of the cerebrovascular autoregulative mechanisms (predominantly neurogenic and myogenic). In healthy normotensive elderly subjects, cerebral autoregulatory capacity is retained but delayed in response to ergometer stress compared with young healthy subjects. We speculate that these findings may contribute to a higher risk of cerebral hypoperfusion in the elderly.

Frequency of spontaneous fist clenching during routine blood pressure measurements and its effect on measurement accuracy

BACKGROUND

Guidelines for office blood pressure reading techniques do not warn us about the possibility that patients may clench their fist during cuff-inflation. It is unknown how often patients do this, and what effect it has on measured blood pressure readings.

DESIGN AND METHODS

We registered double blood pressure readings in 150 outpatient clinic subjects, who were not given specific instructions as to how to hold their hand during the procedure. If they clenched their fist during the first reading, they were asked to relax their hand during the second reading, and vice versa. Double readings with a relaxed hand on both occasions were registered in 100 matched control patients as well.

RESULTS

Twenty-two of 150 patients (15%) spontaneously made a fist during the first reading. No systematic effect (lower or higher blood pressure) from making a fist was observed, but individual effects were often marked, as evidenced by the median absolute differences (regardless of '+' or '-' sign) between the duplicate readings: 5 (range 0-31) versus 3 (0-18) mmHg for systolic blood pressure, and 4 (0-22) versus 2 (0-16) mmHg for diastolic blood pressure in the study group versus the control group, respectively (P < or = 0.05). A different hypertension classification occurred twice as often when a fist was made during one of the two blood pressure readings than with two fistless readings (23 versus 12%, P = 0.04).

CONCLUSION

About one out of every seven patients makes a fist during blood pressure taking. This can seriously affect measurement accuracy, and doubles the risk of misclassification of hypertension.