Hypovolemic intolerance to lower body negative pressure in female runners

Morikawa, Toshihito; Sagawa, Sueko; Torii, R; Endo, Yutaka; Yamazaki, Fumio; Shiraki, Keizō

doi:10.1097/00005768-200112000-00013

Cited by 14 publications

(16 citation statements)

References 18 publications

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“…All investigations demonstrating either negative or neutral effects of aerobic exercise involved the examination of very intense training in young athletes (VO 2 max > 60 mL·kg −1 ·min −1 ) 7-10 and most involved a cross-sectional design. [8][9][10] The only study that involved both a prospective intervention and a subject population of nonathletes demonstrated a large improvement in orthostatic tolerance to upright tilting in young adult military recruits, congruent with the results of this study. 6 To our knowledge, our study is the first to show that even older adults at very high cardiovascular risk due to type 2 diabetes, and age can improve orthostatic tolerance with regular aerobic exercise.…”

Section: Discussionsupporting

confidence: 83%

“…Vigorous aerobic training has been shown to improve orthostatic tolerance in young normal subjects, 6 but some investigations have demonstrated a worsening [7][8][9] or no 10 effect of aerobic training on orthostatic tolerance. The impact of aerobic exercise on GTN-induced orthostatic intolerance in older adults with type 2 diabetes has not been previously examined.…”

Section: Introductionmentioning

confidence: 99%

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Short-term Aerobic Exercise Reduces Nitroglycerin-induced Orthostatic Intolerance in Older Adults With Type 2 Diabetes

Madden

Lockhart²,

Potter³

et al. 2011

Journal of Cardiovascular Pharmacology

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Aims/Hypothesis-Older adults are at a high risk for syncope due to orthostatic intolerance (OI), and this risk increases with comorbid type 2 diabetes and vasoactive medications. Despite many benefits, previous investigations have shown worsening OI with aerobic training. We examined whether aerobic exercise reduced OI in older adults with type 2 diabetes who were given a short-acting vasoactive agent (nitroglycerin).Methods-Forty older adults (25 males and 15 females, mean age 71.4 ± 0.7 years, ranging in age from 65 to 83 years) with type 2 diabetes were recruited. Subjects were randomized to each of 2 groups: an aerobic group (3 months of vigorous aerobic exercise) and a nonaerobic (no aerobic exercise) group. Exercise sessions were supervised by a certified exercise trainer 3 times per week. After being given 400 μg of sublingual nitroglycerin, each subject was placed in a 70° head-up tilt for 30 minutes.Results-When the 2 groups were compared using a Cox proportional hazards model, tilt table tolerance was significantly better in the aerobic group as compared to in the nonaerobic group (χ 2 MC = 7.271, P = 0.007).Conclusions-Our findings indicate that a relatively short aerobic exercise intervention can improve postnitroglycerin orthostatic tolerance in older adults with type 2 diabetes.

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Section: Discussionsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Short-term Aerobic Exercise Reduces Nitroglycerin-induced Orthostatic Intolerance in Older Adults With Type 2 Diabetes

Madden

Lockhart²,

Potter³

et al. 2011

Journal of Cardiovascular Pharmacology

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“…In addition to being a direct vasoconstrictor, angiotensin II increases norepinephrine release from adrenergic nerve terminals and augments the postsynaptic response (29, 30a). Plasma renin activity (PRA) normally increases in response to an orthostatic challenge (12,26,27,41), but this response may be attenuated in some POTS patients (18,21). Jacob et al (18) observed that a subgroup of POTS patients had significantly decreased supine and standing PRA compared with healthy subjects.…”

Section: Discussionmentioning

confidence: 99%

Baroreflex control of muscle sympathetic nerve activity in postural orthostatic tachycardia syndrome

Swift

Charkoudian

Dotson³

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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-Postural orthostatic tachycardia syndrome (POTS) is characterized by excessive tachycardia during orthostasis. To test the hypothesis that patients with POTS have decreased sympathetic neural responses to baroreflex stimuli, we measured heart rate (HR) and muscle sympathetic nerve activity (MSNA) responses to three baroreflex stimuli including vasoactive drug boluses (modified Oxford technique), Valsalva maneuver, and head-up tilt (HUT) in POTS patients and healthy control subjects. The MSNA response to the Valsalva maneuver was significantly greater in the POTS group (controls, 26 Ϯ 7 vs. POTS, 48 Ϯ 6% of baseline MSNA/mmHg; P ϭ 0.03). POTS patients also had an exaggerated MSNA response to 30°HUT (controls, 123 Ϯ 24 vs. POTS, 208 Ϯ 30% of baseline MSNA; P ϭ 0.03) and tended to have an exaggerated response to 45°HUT (controls, 137 Ϯ 27 vs. POTS, 248 Ϯ 58% of baseline MSNA; P ϭ 0.10). Sympathetic baroreflex sensitivity calculated during administration of the vasoactive drug boluses also tended to be greater in the POTS patients; however, this did not reach statistical significance (P ϭ 0.15). Baseline MSNA values during supine rest were not different between the groups (controls, 23 Ϯ 4 vs. POTS, 16 Ϯ 5 bursts/100 heartbeats; P ϭ 0.30); however, resting HR was significantly higher in the POTS group (controls, 58 Ϯ 3 vs. POTS, 82 Ϯ 4 beats/min; P ϭ 0.0001). Our results suggest that POTS patients have exaggerated MSNA responses to baroreflex challenges compared with healthy control subjects, although resting supine MSNA values did not differ between the groups. intolerance; blood pressure; heart rate; Valsalva maneuver; head-up tilt POSTURAL ORTHOSTATIC TACHYCARDIA syndrome (POTS) is a chronic, potentially debilitating condition that often occurs in otherwise healthy individuals who are most often young women. Patients with this condition (also known as idiopathic orthostatic intolerance) exhibit excessive tachycardia [increase in heart rate (HR) of Ͼ30 beats/min] during head-up tilt (HUT) in the absence of significant orthostatic hypotension. They also develop dizziness, fatigue, headache, and/or anxiety with standing or HUT (24,34). Although POTS has become better recognized clinically in recent years, the mechanisms underlying the pathophysiology of this condition remain unclear.In humans, normal baroreflex physiology involves increased HR, increased vascular sympathetic nerve activity, and peripheral vasoconstriction in response to decreased venous return during upright posture (31). These normal responses result in maintenance of arterial pressure with the upright posture and an absence of symptoms such as those reported by POTS patients. It is not clear whether the excessive tachycardia with orthostasis in POTS patients is the cause or the consequence of one or more abnormal steps in the baroreflex pathway. For example, evidence is conflicting regarding baroreflex control of HR in patients with orthostatic intolerance. Some researchers have reported decreased sensitivity of baroreflex control of HR in these ...

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“…Such changes in the leg veins lead to a reduction of blood pressure with a decrease in cardiac filling. It has been thought, therefore, that leg venous distensibility is a determinant of orthostatic tolerance in normothermic humans [41][42][43] . Muscle venous volume accounts for approximately 85% of the leg venous volume in normothermia 44,45) .…”

Section: Increase In Leg Venous Compliancementioning

confidence: 99%

Heat stress and orthostatic tolerance

Yamazaki

2012

JPFSM

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In healthy individuals, exercise and nonexercise (i.e. passive body heating) heat stress induces vulnerability in the cardiovascular system, and is apt to cause hypotension during upright posture, resulting in a reduction of orthostatic tolerance. Reduced orthostatic tolerance is linked to multiple physiological mechanisms including 1) a redistribution of blood flow from central parts of the body to skin, 2) an increase in leg venous compliance, 3) altered baroreflex function, 4) an attenuated venoarterial response in the lower extremities, and 5) a decrease in plasma volume. A combination of countermeasures such as cooling of the body, rehydration, and heat acclimation, can improve orthostatic tolerance in a hot environment. The purpose of this review was to summarize findings investigating the causes of and preventive approaches to heat stress-induced orthostatic intolerance.

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Hypovolemic intolerance to lower body negative pressure in female runners

Cited by 14 publications

References 18 publications

Short-term Aerobic Exercise Reduces Nitroglycerin-induced Orthostatic Intolerance in Older Adults With Type 2 Diabetes

Short-term Aerobic Exercise Reduces Nitroglycerin-induced Orthostatic Intolerance in Older Adults With Type 2 Diabetes

Baroreflex control of muscle sympathetic nerve activity in postural orthostatic tachycardia syndrome

Heat stress and orthostatic tolerance

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