Immersion Of Hand In Cold Water Research Articles

Hand cooling induces changes in the kinetics of oxygen uptake

The objective of this investigation was to assess the impact of elevated catecholamine concentrations, induced through cold-water hand immersion, on the oxygen consumption (V̇O2) kinetics during intense exercise, and to contrast this effect with that of the priming effect. Ten active participants underwent three 8-minute constant work rate exercises (CWR) at ∆25%, with one CWR preceded by hand cooling (2 min at 0 °C, HC) and two consecutive CWR to induced priming effect on the second bout (SB). Pulmonary gas exchange and blood samples were analyzed to measure levels of epinephrine (E) and norepinephrine (NE). Results demonstrated a significant increase in the primary phase amplitude of V̇O2 kinetics in response to both hand HC (33.9 mL.min−1.kg−1; CI [32.2;35.7], p < 0.001) and SB (34.6 mL.min−1.kg−1; CI [33.0;36.3], p < 0.001) relative to the control (32.7 mL.min−1.kg−1; CI [31.5;35.1]). Additionally, the amplitude of the V̇O2 slow component was reduced for both HC (3.2 mL.min−1.kg−1; CI [2.2;4.1], p = 0.018) and SB (2.9 mL.min−1.kg−1; CI [1.8;4.2], p = 0.009) in comparison to control (3.9 mL.min−1.kg−1; CI [2.9;4.2]). These findings suggest that the increase in E and NE induced by hand cooling prior to exercise modifies V̇O2 kinetics in a manner akin to the priming effect. This research underscores the potential role of catecholamines in facilitating the priming effect and its subsequent impact on V̇O2 kinetics. However, further studies are necessary to clearly establish this link.

The Leuven Prolonged Acute Stress Test (L-PAST): A novel paradigm to induce a subjective and glucocorticoid stress response for at least ninety minutes

Laboratory stress tests typically administer stress acutely, ranging from 3 to 15 minutes. However, everyday stressors usually last longer than ten minutes (e.g., examination stressors, work stressors, and social stressors. Moreover, in some studies, it may be relevant to induce stress for a longer period to affect certain psychological or physiological parameters. To this end, we developed a novel stress test that intends to induce psychosocial stress for 90 minutes. The Leuven Prolonged Acute Stress Test (L-PAST) combines physical (hand immersion in cold water), cognitive (mental arithmetic), and psychosocial (social evaluation and feelings of failure) stress elements of two well-known laboratory stress tests, the Maastricht Acute Stress Test (MAST) and the Montreal Imaging Stress Test (MIST). Fifty healthy women were subjected to both the L-PAST and a sham (control) test in a randomized and counterbalanced manner. The stress response was determined by salivary cortisol measurements and assessment of subjective stress ratings at regular time points during the time preceding the stress period (5 min), the stress period (90 min), and the recovery period (35 min). Cognitive reactivity to failure and subjective pain levels were also assessed at various time points. The childhood trauma questionnaire (CTQ) and the perceived stress scale (PSS) were administered prior to the testing phase. As expected, linear mixed models revealed that the stress response was significantly higher during the L-PAST as indicated by a significant time point by condition interaction effect for both the cortisol response (F(10,450)=12.21, p < 0.0001, ηp2=0.11) and the subjective stress response (F(13,637)=13.98, p < 0.0001, ηp2 = 0.12). Moreover, there was a significant time point by condition interaction effect for cognitive reactivity to failure (F(13,637) = 7.97, p < 0.0001, ηp2 = 0.07) and subjective pain (F(13,637) = 38.52, p < 0.0001, ηp2 = 0.27), indicating that the levels were higher during the L-PAST at most stress induction time points. Lastly, higher CTQ scores were associated with higher subjective pain levels during the L-PAST (F(1,44)=6.05, p = 0.02). Collectively, our results confirm the efficacy of the L-PAST in inducing a prolonged subjective as well as cortisol stress response.

Effect of catecholamines stimulation via hand cooling and the priming effect on the oxygen consumption kinetics

Introduction&#x0D; Priming effect has been shown to accelerate the oxygen consumption (V̇O2) kinetics. This phenomenon could be explained by muscle oxygen (O2) enhanced delivery, motor unit recruitment or intracellular O2 enhanced utilization (Goulding et al. 2023). Catecholamines such as epinephrine (E) and norepinephrine (NE) are known to impact the cardiovascular system as well as the respiratory system and metabolic effects (Zouhal et al. 2008). The aim of this study is two folds. Observing the effect of increased E and NE induced by cold-water hand immersion on V̇O2 kinetic during heavy intensity exercise bout (HCWR). Compare the effect of cold-water hand immersion and previous HCWR on V̇O2 kinetic to see if the sympathetic system could partially explain the priming effects.&#x0D; Methods&#x0D; Ten healthy active males (mean ± SD, age 23 ± 5 years, body mass 71 ± 6.5 kg) participated in this study. An incremental test was performed on ergometer to prescribe the intensity for the HCWR exercise (∆ 25%). Participants did an 8 min HCWR normal bout (NO), followed by 8 min rest and a second bout (SB) and hand cooling bout (HC) at heavy intensity in a randomized order. For the HC condition, participants put hands in cold water (0°C) for 2 min then directly did the HCWR. Blood samples has been taken at rest, before and directly after the HCWR.&#x0D; Results&#x0D; Just before exercise, all conditions were different, but HC E (1.095 ± 0.64 nmol/ml) increased by 347% while HC NE (6.98 ± 1.89 nmol/ml) matched values from SB NE (6.89 ± 2.22 nmol/ml). At the end of exercise, no significant difference has been found between NO E (1.44 ± 1.06) and HC E (1.54 ± 1.38 nmol/ml) while SB E (2.35 ± 1.55 nmol/ml) was significantly higher than both conditions but no differences have been found between HC (20.15 ± 8.76 nmol/ml) and SB (20.41 ± 9.74 nmol/ml) NE. V̇O2 kinetic has been sped up for both HC and SB by increasing the absolute primary prime amplitude of HC (33.88 ± 0.96 ml/min/kg),SB (34.60 ± 0.86ml/min/kg) compared to NO (32.75 ± 0.65 ml/min/kg) and reducing the prime amplitude of HC (3.22 ± 0.51 ml/min/kg), SB (2.90 ± 0.64 ml/min/kg) vs NO (3.87 ±0 .56 ml/min/kg) of the slow component of V̇O2.&#x0D; Discussion/Conclusion&#x0D; Catecholamines stimulation via hand cooling accelerated the V̇O2 kinetics enhancing the primary phase and reducing the slow component. This effect seemed to follow the priming effect but with less intensity. Increased O2 delivery appeared to be a common feature of both conditions, Motor neuron excitability due to increased NE was also a likely hypothesis, as both HC and SB had the same values just before exercise. Finally, intra-muscular enhancement illustrated by improved intracellular partial pressure kinetics and mitochondrial O2 utilization might explain the effects of catecholamines and part of the priming effect. Mitochondrial “warm-up” could be influenced by both catecholamines and priming effect resulting in a better production of adenosine triphosphate.&#x0D; References&#x0D; Goulding, R. P., Burnley, M., &amp; Wüst, R. C. I. (2023). How priming exercise affects oxygen uptake kinetics: From underpinning mechanisms to endurance performance. Sports Medicine, 53, 959-976. https://doi.org/10.1007/s40279-023-01832-1&#x0D; Zouhal, H., Jacob, C., Delamarche, P., &amp; Gratas-Delamarche, A. (2008). Catecholamines and the effects of exercise, training and gender. Sports Medicine 38, 401-423. https://doi.org/10.2165/00007256-200838050-00004

Investigating manual performance when using push buttons following cold water hand immersion

The purpose of this study was to investigate manual performance of humans when using push buttons following cold water hand immersion. An experiment involving 29 human participants was carried out to measure the activation rate of twelve different shaped push buttons mounted on a novel test apparatus after their dominant hand was immersed in cold (2 °C) and thermoneutral (34 °C) water for 2 min. A series of standardized hand dexterity tests were completed to assess the participants' baseline tactile sensitivity in a dry thermoneutral state. The mean baseline performance of participants indicates that they were representative of the general population. The button test apparatus was developed specifically for this experiment and was comprised of 12 different buttons at different locations on the panel which were varying in size, surface shape and texture. After the participants immersed their dominant hand in the assigned temperature condition, their index finger was guided to the centre of the panel, and they were instructed to find and press as many buttons as they could in a 2-min time period using only their index finger. For the button panel test, the participants’ view was obstructed from seeing the buttons. The results of the study indicate that temperature does not influence the activation rate of the push buttons on the button test apparatus. In addition, button size (large) was the most significant factor, followed by shape (protruding), however button texture was not a significant parameter. Given that exposure to cold water reduces manual performance, along with anecdotal evidence from survival training centres that users sometimes struggle to activate PLBs, the motivation for this research was to understand how humans interact with these devices in cold water emergency situations. It is expected that the results of this research will be useful for designers of emergency signalling devices used for rescue at sea.

0163 Impact of cold-water hand immersion on cognitive performance and sleepiness during sleep inertia

Abstract Introduction Sleep inertia is a state of impaired cognitive performance upon awakening that dissipates with time awake. Manipulation of the distal-to-proximal skin temperature gradient using cold water has been hypothesized as a potential countermeasure to sleep inertia, but not previously explored (Krauchi et al., 2004). This study examined the effects of cold-water hand immersion on subsequent cognitive performance and sleepiness during sleep inertia. Methods Ten healthy adults (mean±standard deviation [SD] age 23.2±4.96 years; 6M, 4F) have thus far completed an ongoing 8-day protocol. Prior to an overnight in-laboratory visit, participants maintained habitual 8h sleep schedules for 1 week at home. In-laboratory sleep opportunities were timed to coincide with habitual sleep time. Following at least 5-min of electroencephalogram (EEG) verified continuous slow wave sleep (SWS), participants were awakened twice during the night to submerge their non-dominant hand in warm (34 C) or ice-cold water (0 C) for 3 min in a randomized, crossover design. Sleep inertia was assessed with a Mathematical Addition Test (ADD) and the Karolinska Sleepiness Scale (KSS) at ~ 5, 15, and 25 min after each awakening. Outcomes included number of correct responses and median reaction time for correct responses on the ADD and KSS scores. Data were analyzed with mixed-model ANOVA with condition, condition order and time since awakening as fixed factors and subject as a random factor. Results The average (Mean±SD) amount of SWS prior awakening was similar before the cold 7.0±2.3 min and warm 6.6±1.0min conditions (p&amp;gt;0.10). Following cold water immersion, subjective sleepiness was reduced and the median reaction time for correct responses was faster compared with warm water immersion (main effects of condition, p’s&amp;lt; 0.05). The number of correct responses was not significantly different between conditions, nor were there any significant interaction effects among the fixed factors. Conclusion These preliminary findings indicate that cold-water hand immersion may reduce sleepiness and increase the speed of arithmetic calculations during sleep inertia, which could have important implications for military and first responders performing after awakenings from sleep. Support (if any) Office of Naval Research MURI N00014-15-1-2809; NIH RHL165343A and CTSA Grant UL1 TR002535; Undergraduate Research Opportunities Grant, University of Colorado Boulder.

Influence of acute beetroot juice supplementation on cold-induced vasodilation and fingertip rewarming.

Vasoactive ingredients in beetroot (BR) such as nitrate are known to induce vasodilation in temperate conditions. This study investigated the effect of BR ingestion on cold induced vasodilation (CIVD) and rewarming of finger skin temperature (Tfing) during and after hand immersion in cold water. Twenty healthy males (mean ± SD; age 22.2 ± 0.7 years, height 172.6 ± 6.0cm, body mass 61.3 ± 11.7kg) repeated a hand cold water immersion test twice with prior BR or water beverage ingestion (randomised order). They rested for 2h in thermoneutral conditions (27°C, 40% relative humidity) after consuming the beverage, then immersed their non-dominant hand in 8°C water for 30min. They then rewarmed their hand in the ambient air for 20min. Skin temperature at seven body sites, Tfing, finger skin blood flow (SkBFfing), and blood pressure were measured. During hand immersion parameters of CIVD (Tfing and SkBFfing) were not different between BR and water conditions although skin temperature gradient from proximal to distal body sites was significantly smaller with BR (P < 0.05). During rewarming, SkBFfing and cutaneous vascular conductance were significantly higher with BR than with water (P < 0.05). The rewarming speed in Tfing and SkBFfing was significantly faster with BR at 15- (BR 1.24 ± 0.22 vs water 1.11 ± 0.26°C/min) and 20-min rewarming (P < 0.05). Additionally, individuals with slower rewarming speed with water demonstrated accelerated rewarming with BR supplementation. BR accelerated rewarming in Tfing and SkBFfing after local cold stimulus, whereas, CIVD response during hand cold immersion was not affected by BR ingestion.

Inhibition of current perception thresholds in A-delta and C fibers through somatosensory stimulation of the body surface

Somatosensory stimulation of the body surface, such as through tactile and noxious stimulation, is widely known to inhibit pain. However, no studies have measured the threshold changes due to somatosensory stimulation of each nerve fiber (Aβ, Aδ, and C) separately. We examined the changes in the current perception thresholds of Aδ, C, and Aβ fibers induced by non-noxious and noxious somatosensory stimulation of the body surface. The current stimuli were sinusoidal waves at frequencies of 2000 Hz, 250 Hz, and 5 Hz, which selectively stimulated the Aβ, Aδ, and C fibers, respectively. In the case of non-noxious stimulation, lightly rubbing the dorsal side of the forearm with a brush showed no significant physiological or clinical changes in the current perception thresholds of the Aδ, and C fibers; a significant increase was observed only in the Aβ fibers. However, applying noxious stimulation to the body surface through hand immersion in cold water increased pain thresholds in both the Aδ and C fibers, and sensory threshold of the Aβ fibers; changes in tactile thresholds were not significant. Inhibition of sensory information by nociceptive inputs may selectively suppress nociceptive stimuli.

Hyper-connectivity between the left motor cortex and prefrontal cortex is associated with the severity of dysfunction of the descending pain modulatory system in fibromyalgia.

IntroductionThe association between descending pain modulatory system (DPMS) dysfunction and fibromyalgia has been previously described, but more studies are required on its relationship with aberrant functional connectivity (FC) between the motor and prefrontal cortices.ObjectivesThe objective of this cross-sectional observational study was to compare the intra- and interhemispheric FC between the bilateral motor and prefrontal cortices in women with fibromyalgia, comparing responders and nonresponders to the conditioned pain modulation (CPM) test.MethodsA cross-sectional sample of 37 women (23 responders and 14 nonresponders to the CPM test) with fibromyalgia diagnosed according to the American College of Rheumatology criteria underwent a standardized clinical assessment and an FC analysis using functional near-infrared spectroscopy. DPMS function was inferred through responses to the CPM test, which were induced by hand immersion in cold water (0–1°C). A multivariate analysis of covariance for main effects between responders and nonresponders was conducted using the diagnosis of multiple psychiatric disorders and the use of opioid and nonopioid analgesics as covariates. In addition, we analyzed the interaction between the CPM test response and the presence of multiple psychiatric diagnoses.ResultsNonresponders showed increased FC between the left motor cortex (lMC) and the left prefrontal cortex (lPFC) (t = −2.476, p = 0.01) and right prefrontal cortex (rPFC) (t = −2.363, p = 0.02), even when both were considered as covariates in the regression analysis (lMC–lPFC: β = −0.127, t = −2.425, p = 0.021; lMC–rPFC: β = −0.122, t = −2.222, p = 0.033). Regarding main effects, a significant difference was only observed for lMC–lPFC (p = 0.035). A significant interaction was observed between the psychiatric disorders and nonresponse to the CPM test in lMC−lPFC (β = −0.222, t = −2.275, p = 0.03) and lMC−rPFC (β = −0.211, t = −2.2, p = 0.035). Additionally, a significant interaction was observed between the CPM test and FC in these two region-of-interest combinations, despite the psychiatric diagnoses (lMC−lPFC: β = −0.516, t = −2.447, p = 0.02; lMC−rPFC: β = −0.582, t = −2.805, p = 0.008).ConclusionsHigher FC between the lMC and the bilateral PFC may be a neural marker of DPMS dysfunction in women with fibromyalgia, although its interplay with psychiatric diagnoses also seems to influence this association.

Erythromelalgie primitive, une nouvelle observation

Erythromelalgia is a vascular acrosyndrome first described by Mitchell in 1878. It is rare, affecting the feet more than the hands, and the symptoms are triggered by heat and calmed by cold. There are two types: the primary form (exceptional hereditary form and non-familial idiopathic form), the secondary form (associated with hematological disorders and systemic diseases). The exact mechanism is the subject of controversy. It has an important functional impact. We report a new observation. It was a 39-year-old woman, multiparous, in a polygamous marriage, residing in Gao, referred to the emergency room on February 12, 2018 for severe hand pain. She had presented with the same episode in March 2011 relieved by hand immersion in cold water associated with an unidentified analgesic. No similar conditions were found in her family. On examination, the general condition was good, we noted a large placard of both hands, red with a salmon appearance, taking the eminences in a V shape, sparing the back of the hands. The lesion was warm and painful to the touch, without any portal of entry (A, B, C). Blood count, sedimentation rate, blood glucose and antinuclear antibodies were normal. 500mg/day acetylsalicylic acid treatment was instituted. The evolution under this treatment was favorable with complete remission after two weeks (D). The diagnosis of primary idiopathic erythromelalgia was evoked in view of the patient's age, the clinical and biological signs and the response to treatment.

Local hyperalgesia, normal endogenous modulation with pain report beyond its origin: a pilot study prompting further exploration into plantar fasciopathy.

Background and aims Persistent tendinopathies were previously considered solely as peripheral conditions affecting the local tendinous tissue until quantitative sensory testing identified involvement of altered pain processing. In similar fashion, pain in patients with persistent plantar fasciopathy may also involve more than local tissue. The aim of this pilot study was to investigate potential differences in conditioned pain modulation and pressure and thermal pain thresholds, between individuals with PF and healthy pain-free controls, as a precursor to a larger-scale study. Methods We assessed 16 individuals with plantar fasciopathy and 11 pain-free controls. Plantar fasciopathy diagnosis was: palpation pain of the medial calcaneal tubercle or the proximal plantar fascia, duration ≥3 months, pain intensity ≥2/10, and ultrasound-measured plantar fascia thickness ≥4 mm. Quantitative sensory tests were performed locally at the plantar heel and remotely on the ipsilateral elbow. Assessments included pain thresholds for pressure, heat and cold, and conditioned pain modulation measured as change in local resting pressure pain threshold with cold water hand immersion. Participants rated pain intensity at pain threshold. Additionally, the area and distribution of plantar fasciopathy pain was drawn on a digital body chart of the lower limbs. Descriptive analyses were performed and between-group differences/effects expressed as standardised mean differences (d). Results There was no conditioned pain modulation difference between participants with plantar fasciopathy and controls (d = 0.1). Largest effects were on local pressure pain threshold and reported pain intensity on pressure pain threshold (d > 1.8) followed by pain intensity for heat and cold pain thresholds (d = 0.3-1.5). According to the digital body chart, pain area extended beyond the plantar heel. Conclusions The unlikelihood of a difference in conditioned pain modulation yet a pain area extending beyond the plantar heel provide a basis for exploring altered pain processing in a larger-scale study. Implications This was the first study to investigate the presence of altered pain processing in individuals with plantar fasciopathy using a conditioned pain modulation paradigm and thermal pain thresholds. We found no indication of an altered pain processing based on these measures, however, patients rated pain higher on thresholds compared to controls which may be important to clinical practice and warrants further exploration in the future.

Investigating Effects of Cold Water Hand Immersion on Selective Attention in Normobaric Hypoxia.

This study investigated the effect of cold-water hand immersion on selective attention as measured by the Stroop Color Word Test in nomorbaric normoxia and hypoxia. Ten healthy men rested for 60 min, after which they immersed their non-dominant hand into 5 °C water for 15 min. The interference score of the Stroop Color Word Test and thermal sensation were measured at baseline in the final 5 min of resting and in the final 5 min of cold water hand immersion. The interference score was not influenced by hypoxia but was found to be significantly improved compared to resting in both conditions during cold water hand immersion. Selective attention improved during 15 min of cold-water hand immersion, with increased thermal sensations rated as “very cool” of the immersed arm. Cold-water hand immersion may be helpful in improving cognitive function in normoxia and normobaric hypoxia.

Acute effects of salbutamol on systemic vascular function in people with asthma.

Asthmatics are at increased cardiovascular disease risk, which has been linked to beta2(β2)-agonist use. Inhalation of β2-agonists increases sympathetic nerve activity (SNA) in healthy individuals, however the systemic impact of salbutamol in asthmatics using β2-agonists regularly is unknown. This study compared the systemic vascular responses to a clinical dose of salbutamol (Phase I) and following an acute increase in SNA (Phase II) in asthmatics and controls. Fourteen controls and 14 asthmatics were recruited for Phase I. On separate days, flow-mediated dilation (FMD) and peripheral arterial stiffness (pPWV) were evaluated at baseline and following either 400 μg inhaled salbutamol or a placebo inhaler. For Phase II, heart rate, blood pressure, vascular conductance, pPWV, and central (c)PWV were evaluated in response to a large increase in SNA brought on by cold-water hand immersion (i.e. cold-pressor test) or body-temperature water hand immersion (i.e. control) in 10 controls and 10 asthmatics. Following salbutamol, asthmatics demonstrated reduced FMD (-3.0%, p<0.05) and increased pPWV (+0.7m/s, p<0.05); however, salbutamol had no effect in controls. The cold-pressor test resulted in similar increases in blood pressure, vascular flow rates and conductance, pPWV, and cPWV in both asthmatics and controls, suggesting similar neurovascular transduction in asthmatics and controls. Inhaled Salbutamol leads to increased arterial stiffness and reduced FMD in asthmatics. As asthmatics and controls had similar vascular responses to an increase in SNA, these findings suggest asthmatics have heightened sympathetic responses to β2-agonists which may contribute to the increased cardiovascular risk in asthma.

(352) Sex Differences in Sensory Processing: The Role of Stimulus Modality ad Psychological Factors

The experience of pain varies greatly from person to person. Many factors affect individual differences in pain, including sex and psychological factors. Previous studies have separately examined the effects of sex and psychological factors on pain, but most have not examined them in combination. The aim of this preliminary, exploratory analysis was to investigate sex differences in pain in a large sample to determine how pain responses and psychological measures of males compare to those of females using multiple quantitative sensory testing paradigms and multiple psychological measures. 141 participants (55 males, 86 females, mean age=29.1±6.8) were exposed to noxious heat, cold, and non-noxious audio stimuli. Participants were asked to rate their pain intensity and unpleasantness from thermal stimuli and the loudness of auditory stimuli. Psychological measures included the Barratt Impulsiveness Scale, Positive and Negative Affect Scale, PROMIS Anxiety, PROMIS Depression, PROMIS Pain Interference, and Pain Catastrophizing Scales. Univariate analyses and multiple linear models were constructed. Significant sex differences were found for cold and auditory stimuli but not heat. Females had lower cold tolerance during cold water hand immersion (means: males=76.2 seconds, females=59.7 seconds; p=.010). However, for 0.5°C cold phasic contact stimuli, males had greater pain intensity ratings (means: males=1.8, females=1.1; p=.030), and pain unpleasantness ratings (means: males=1.5, females= 0.9; p=0.040). Males had greater sensitivity to auditory stimuli as demonstrated by higher auditory unpleasantness ratings (means: males=4.1, females= 3.1; p=.049). Sex differences in psychological measures were found only for anxiety, which was greater in females (means: males=11.2, females=13.7; p=.006) and impulsivity, which was greater in males (means: males=56.0, females=51.7; p=.003). After adjusting for anxiety and impulsivity, the sex differences in cold pain tolerance, contact cold pain, and auditory sensitivity were not significantly different. Thus, sex differences in sensory processing are modality specific but may arise from sex differences in psychological factors.

Electroencephalographic frontal synchrony and caudal asynchrony during painful hand immersion in cold water.

Recent studies in our laboratory showed that cortical theta oscillations correlate with pain in rodent models. In this study, we sought to validate our pre-clinical data using EEG recordings in humans during immersion of the hand in ice cold water, a moderately noxious stimulus. Power spectral analysis shows that an increase in pain score is associated with an increase in power amplitude within a frequency range of 6-7Hz at the frontal (Fz) electrode. These results are consistent with our previous pre-clinical animal studies and the clinical literature. We also report a novel reduction in power at the caudal (O1) electrode within a broader 3-30Hz rand and decreased coherence between Fz and C3, C4 electrodes within the theta (4-8Hz) and low beta (13-21Hz) bands, while coherence (an indirect measure of functional connectivity) between Fz and O1 increased within the theta and alpha (8-12Hz) bands. We argue that pain is associated with EEG frontal synchrony and caudal asynchrony, leading to the disruption of cortico-cortical connectivity.

(184) Pain sensitivity is associated with vigorous physical activity and high cardiorespiratory fitness

Current activity recommendations are based primarily on epidemiologic evidence of an inverse relationship between volume of physical activity (PA) and overall risk of chronic disease, disability, and ultimately, mortality. Although exercise is often recommended to prevent and treat chronic pain conditions, whether or not greater physical activity reduces pain sensitivity remains unclear. Thus, the primary goal of this study was to compare pain sensitivity in highly active and sedentary adults. We assessed pain sensitivity, 7-day PA, and cardiorespiratory fitness in 59 pain-free adults (29F, 30M; 18-45 yrs). Pain sensitivity was assessed using pressure pain thresholds (PPTs) of the middle deltoid, pressure temporal summation (TS) of the dorsal forearm, and conditioned pain modulation (CPM) using middle deltoid PPTs before and after contralateral cold water hand immersion. PA was assessed via self-report (International Physical Activity Questionnaire) and wrist-worn accelerometry (Actigraph; ± 6g triaxial). Cardiorespiratory fitness was estimated using a submaximal step test to classify participants as having low, average, or high fitness. PPTs were highest (lowest sensitivity) in the high fitness group (p ≤ 0.01) while no differences were noted between fitness groups for TS (p = 0.21) or CPM (p = 0.97). Pressure pain sensitivity decreased with increasing levels of self-reported and measured (accelerometry) vigorous PA (rs = 0.44, p ≤ 0.01). Less TS was observed with increasing vigorous self-reported PA only (rs = -0.29, p < 0.05), while CPM was not associated with activity level. These results suggest that PPTs are more sensitive to physical activity and fitness differences than pressure TS or CPM in a young, healthy cohort. Supported in part by University of Iowa Physical Therapy & Rehabilitation Science Department, University of Iowa, Carver College of Medicine NIH Training Grant, and NIH CTSA U54TR001013.

Acute Effects of Normobaric Hypoxia on Hand-Temperature Responses During and After Local Cold Stress

The purpose was to investigate acute effects of normobaric hypoxia on hand-temperature responses during and after a cold-water hand immersion test. Fifteen males performed two right-hand immersion tests in 8°C water, during which they were inspiring either room air (Fio2: 0.21; AIR), or a hypoxic gas mixture (Fio2: 0.14; HYPO). The tests were conducted in a counterbalanced order and separated by a 1-hour interval. Throughout the 30-min cold-water immersion (CWI) and the 15-min spontaneous rewarming (RW) phases, finger-skin temperatures were measured continuously with thermocouple probes; infrared thermography was also employed during the RW phase to map all segments of the hand. During the CWI phase, the average skin temperature (Tavg) of the fingers did not differ between the conditions (AIR: 10.2 ± 0.5°C, HYPO: 10.0 ± 0.5°C; p = 0.67). However, Tavg was lower in the HYPO than the AIR RW phase (AIR: 24.5 ± 3.4°C; HYPO: 22.0 ± 3.8°C; p = 0.002); a response that was alike in all regions of the immersed hand. Accordingly, present findings suggest that acute exposure to normobaric hypoxia does not aggravate the cold-induced drop in hand temperature of normothermic males. Still, hypoxia markedly impairs the rewarming responses of the hand.

Biologic Measures as Epidemiological Indicators of Risk for the Development of Hypertension in an African American Adolescent Population

Globally, the health disparity of hypertension is disproportionately greater within the African American population and develops at an earlier age. Elevated and continuous interaction of biologic measures during adolescence may be precursors and indicators of risk for blood pressure changes and the subsequent development of adult essential hypertension. The purpose of this study was to describe (1) the prevalence of biologic measures of risk of hypertension, specifically family history of hypertension, prehypertension, elevated salivary cortisol, and hyperresponsive cortisol and cardiovascular reactivity, and (2) the gender difference in the prevalence of biologic risk factors of hypertension. This was an exploratory descriptive design with a nonrandom purposive sample. Participants (N = 106) were high school, African American adolescents, aged 14 to 18 years. Data, including family history of hypertension, resting blood pressure, and blood pressure and cortisol levels before and after induced physiologic stress by cold water hand immersion, were measured. One hundred six African American participants (49 males and 57 females) completed the study. Data described that 71% had a positive family history of hypertension. Overall, the resting blood pressures were 120 mm Hg for systolic and 68 mm Hg for diastolic. Forty-one percent of the patients had prehypertensive blood pressures; 86% had elevated cortisol; 49% had hyperresponsive blood pressure reactivity; and 35% had cortisol hyperresponsivity. Excluding ethnicity, 65% had 3 or more biologic measures of risk of hypertension. Statistically significant gender differences included male systolic pressure and number of males with prehypertension. This study provides evidence of the high prevalence of multiple physiologic biologic measures of risk of hypertension factors within a vulnerable population. The continuous interaction of biologic measures over time may increase the susceptibility and risk of essential hypertension development and supports the development of appropriate physiologically based behavioral interventions.

Hard‐wired for hypertension? The sympathetic nervous system causing havoc to non‐responders’ blood pressure

Hard‐wired for hypertension? The sympathetic nervous system causing havoc to non‐responders’ blood pressure

The Effect of a Sleep High–Train Low Regimen on the Finger Cold-Induced Vasodilation Response

The present study evaluated the effect of a sleep high-train low regimen on the finger cold-induced vasodilation (CIVD) response. Seventeen healthy males were assigned to either a control (CON; n=9) or experimental (EXP; n=8) group. Each group participated in a 28-day aerobic training program of daily 1-h exercise (50% of peak power output). During the training period, the EXP group slept at a simulated altitude of 2800 meters (week 1) to 3400 m (week 4) above sea level. Normoxic (CIVD(NOR); CON and EXP groups) and hypoxic (CIVD(HYPO); F(I)O(2)=0.12; EXP group only) CIVD characteristics were assessed before and after the training period during a 30-min immersion of the hand in 8°C water. After the intervention, the EXP group had increased average finger skin temperature (CIVD(NOR): +0.5°C; CIVD(HYPO): +0.5°C), number of waves (CIVD(NOR): +0.5; CIVD(HYPO): +0.6), and CIVD amplitude (CIVD(NOR): +1.5°C; CIVD(HYPO): +3°C) in both CIVD tests (p<0.05). In contrast, the CON group had an increase in only the CIVD amplitude (+0.5°C; p<0.05). Thus, the enhancement of aerobic performance combined with altitude acclimatization achieved with the sleep high-train low regimen contributed to an improved finger CIVD response during cold-water hand immersion in both normoxic and hypoxic conditions.

Gender Differences in the Effects of Acute Stress on Spatial Ability

Although reports that men and women differ in spatial ability are common, recent research examining stress effects on spatial navigation have not included analyses of gender differences. The current study investigated cue perception and mental rotation after an acute cold-water hand immersion stress in 156 undergraduates from the western United States. Gender differences were observed in spatial performance and spatial anxiety. Discriminant analysis revealed that distal gradient cue identification and mental rotation reaction times as well as spatial anxiety differed among men and women exposed to the acute stress and their warm-water hand immersion controls. These results indicate that stress differentially alters spatial performance in men and women, and underscores the importance of assessing gender differences when examining spatial ability.