Head Trauma not Associated with Long Term Effects on Autonomic Function.

Contact-sports can elicit concussions, which impacts autonomic function, as well as elicit repetitive head trauma, where autonomic function has not yet been assessed. The purpose of this study was to determine if differences in autonomic function exist among three groups (CTRL: healthy non-contact-sport participant, RHT: repetitive head trauma contact-sport participant, CONC: previous concussion). Forty participants (16 men and 24 women), aged 18-37 (22 ± 3), participated in the study.

The Influence of a Total Body Resistance Training Program on Autonomic Modulation and Strength Variables in Young Adults.

The purpose of this study was to examine autonomic modulation using multiple quantitative measures before and after a resistance training (RT) intervention. Seventeen young adults (age 18-35 years) were tested for body composition, muscular strength, and autonomic activity. The RT protocol targeted total-body large muscle groups, which were performed three days a week for eight-weeks.

Comparison of Body Composition Prediction Equations with Air Displacement Plethysmography in Overweight and Obese Caucasian Males.

Unlabelled: Body mass index (BMI) has been used for years by clinicians to approximate total body fat. However, the body adiposity index (BAI), body adiposity index from the FELS longitudinal study (BAIFELS), and an equation developed by Deurenberg et al. (BFD) were created recently to offset BMI's limitations and accurately estimate percent body fat (%BF).

Effect of Sex and Menstrual Cycle on Skin Sensory Nerve Contribution to Local Heating.

The purpose of this study was to determine sex differences in the contribution of sensory nerves to rapid cutaneous thermal hyperemia. Healthy young females ( = 15, tested during both the early follicular (EF) and the mid-luteal (ML) phase of the menstrual cycle) and males ( = 15) had a 4 cm2 area of skin on one forearm and one leg treated with a eutectic mixture of local anesthetic (EMLA). EMLA sites, along with corresponding control sites, were instrumented with laser Doppler flowmetry probes and local skin heaters.

Postural orthostatic tachycardia syndrome in primary care: diagnosis, treatment and a case of African-American man presenting with POTS.

Postural orthostatic tachycardia syndrome (POTS) is a heterogeneous autonomic disorder characterised by orthostatic intolerance and a rise in heart rate by at least 30 bpm or an absolute heart rate value of at least 120 bpm within 10 min of standing or during a tilt table test. Overwhelmingly, POTS affects young Caucasian women, which can lead physicians to miss the diagnosis in men or non-white patients. We describe a case of 29-year-old African-American man who developed lightheadedness, generalised weakness, tachycardia and palpitations and was subsequently diagnosed with POTS.

Effect of sympathetic nerve blockade on low-frequency oscillations of forearm and leg skin blood flow in healthy humans.

Objective: To Examine the effect of inhibiting sympathetic function on cutaneous vasomotion in the forearm and leg.

Methods: Intradermal microdialysis fibers were placed in the forearm and leg, one as an untreated control (lactated Ringer's) and the other perfused with bretylium tosylate to block sympathetic nerves. Skin blood flow was monitored using laser Doppler flowmetry.

Neuropeptide Y not involved in cutaneous vascular control in young human females taking oral contraceptive hormones.

We previously reported that the cutaneous vasodilator response to local warming in males required noradrenaline (NA) and neuropeptide-Y (NPY). Animal work has shown no role for NPY in female vascular control. We investigated the contribution of NA and NPY in human female cutaneous vascular control.

The effect of heating rate on the cutaneous vasomotion responses of forearm and leg skin in humans.

We examined skin blood flow (SkBF) and vasomotion in the forearm and leg using laser-Doppler fluxmetry (LDF) and spectral analysis to investigate endothelial, sympathetic, and myogenic activities in response to slow (0.1 °C·10 s(-1)) and fast (0.5 °C·10 s(-1)) local heating.

Oscillatory lower body negative pressure impairs task related functional hyperemia in healthy volunteers.

Neurovascular coupling refers to the link between an increase in neural activity in response to a task and an increase in cerebral blood flow denoted "functional hyperemia." Recent work on postural tachycardia syndrome indicated that increased oscillatory cerebral blood flow velocity (CBFv) was associated with reduced functional hyperemia. We hypothesized that a reduction in functional hyperemia could be causally produced in healthy volunteers by using oscillations in lower body negative pressure (OLBNP) to force oscillations in CBFv.

The contribution of sensory nerves to the onset threshold for cutaneous vasodilatation during gradual local skin heating of the forearm and leg.

During local skin heating, the temporal onset of vasodilatation is delayed in the leg compared to the forearm, and sensory nerve blockade abolishes these differences. However, previous work using rapid skin heating did not allow for determination of sensory nerve influences on temperature thresholds for vasodilatation. Two sites were examined on both the forearm and leg, one control (CTRL), and one treated for sensory nerve blockade (EMLA).

The contribution of sensory nerves to cutaneous vasodilatation of the forearm and leg to local skin heating.

Purpose: The initial cutaneous vasodilatory response to local skin heating is larger in the forearm than the leg. While the initial vasodilatation of the forearm to local heating is primarily dependent on sensory nerves, their role in the leg is unknown. We compared the contribution of sensory nerves in driving the cutaneous vasodilatory response of the forearm and leg to local heating using local anaesthetic (EMLA) cream.

Comparison of the noradrenergic sympathetic nerve contribution during local skin heating at forearm and leg sites in humans.

Purpose: We investigated the role of noradrenergic sympathetic nerves in the cutaneous circulation at rest and in response to local heating.

Methods: Dorsal forearm and lateral leg sites were each instrumented with 2 microdialysis fibers, 2 local skin heaters, and 2 laser-Doppler probes. All sites were heated from 33° to 42 °C.

Oscillatory cerebral blood flow is associated with impaired neurocognition and functional hyperemia in postural tachycardia syndrome during graded tilt.

We hypothesize that upright cognitive impairment in patients with postural tachycardia syndrome (POTS) is caused by reduced cerebral blood flow (CBF). The CBF velocity (CBF(v)) measured by transcranial Doppler ultrasound decreased excessively during 70° tilt in a minority of patients with intermittent hyperpnea/hypocapnia. Incremental tilt showed no difference in mean CBF(v).

To reheat, or to not reheat: that is the question: the efficacy of a local reheating protocol on mechanisms of cutaneous vasodilatation.

The aim of this study is to determine the effect of repeated bouts of local skin heating on the roles of nitric oxide synthase (NOS) and sympathetic nerves in cutaneous vasodilatation. In 3 repeated-heating protocols skin blood flux of the forearm and leg was measured using laser-Doppler flowmetry and data are presented as cutaneous vascular conductance (CVC; flux/blood pressure). Local heating was performed from 33°C (thermoneutral) to 42°C at 0.

Altered oscillatory cerebral blood flow velocity and autoregulation in postural tachycardia syndrome.

Decreased upright cerebral blood flow (CBF) with hyperpnea and hypocapnia is seen in a minority of patients with postural tachycardia syndrome (POTS). More often, CBF is not decreased despite upright neurocognitive dysfunction. This may result from time-dependent changes in CBF.

Blunted cerebral blood flow velocity in response to a nitric oxide donor in postural tachycardia syndrome.

Cognitive deficits are characteristic of postural tachycardia syndrome (POTS). Intact nitrergic nitric oxide (NO) is important to cerebral blood flow (CBF) regulation, neurovascular coupling, and cognitive efficacy. POTS patients often experience defective NO-mediated vasodilation caused by oxidative stress.

Noninvasive examination of endothelial, sympathetic, and myogenic contributions to regional differences in the human cutaneous microcirculation.

The aim of this study was to examine whether there are regional differences in the cutaneous microvascular responses of the forearm and the leg. Utilizing a non-invasive measure (spectral analysis),we looked at the influence of the endothelial, sympathetic, and myogenic function between regions at thermoneutral conditions (33 °C) and in response to local skin warming (42 °C) using laser-Doppler flowmetry (LDF). We recruited 18 young, healthy participants, who visited the lab on 2 separate occasions.

Reduced cerebral blood flow with orthostasis precedes hypocapnic hyperpnea, sympathetic activation, and postural tachycardia syndrome.

Hyperventilation and reduced cerebral blood flow velocity can occur in postural tachycardia syndrome (POTS). We studied orthostatically intolerant patients, with suspected POTS, with a chief complaint of upright dyspnea. On the basis of our observations of an immediate reduction of cerebral blood flow velocity with orthostasis, we hypothesize that the resulting ischemic hypoxia of the carotid body causes chemoreflex activation, hypocapnic hyperpnea, sympathetic activation, and increased heart rate and blood pressure in this subset of POTS.

The regional differences in the contribution of nitric oxide synthase to skin blood flow at forearm and lower leg sites in response to local skin warming.

We investigated the role of nitric oxide synthase (NOS) on regional cutaneous vascular function at rest (thermoneutral conditions) and during the vasodilator response to increased local skin temperature (Tloc). Dorsal forearm and lateral leg sites were instrumented with microdialysis fibers, local heaters, and laser-Doppler probes. All sites were heated from 33 °C to 42 °C.

Effects of forearm vs. leg submersion in work tolerance time in a hot environment while wearing firefighter protective clothing.

This study compared physiological responses and total work tolerance time following forearm submersion (FS) or leg submersion (LS) in cool water, after performing work in a hot environment while wearing fire fighting protective clothing (FPC). Participants walked at 3.5 mph on a treadmill in a hot environment (WBGT 32.