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Compared with younger adults, passive heating induced increases in cardiac output are attenuated by ∼50% in older adults. This attenuated response may be associated with older individuals’ inability to maintain stroke volume through ionotropic mechanisms and/or through altered chronotropic mechanisms. The purpose of this study was to identify the interactive effect of age and hyperthermia on cardiac responsiveness to dobutamine-induced cardiac stimulation. Eleven young (26 ± 4 yr) and 8 older (68 ± 5 yr) participants underwent a normothermic and a hyperthermic (baseline core temperature +1.2°C) trial on the same day. In both thermal conditions, after baseline measurements, intravenous dobutamine was administered for 12 min at 5 µg/kg/min, followed by 12 min at 15 µg/kg/min. Primary measurements included echocardiography-based assessments of cardiac function, gastrointestinal and skin temperatures, heart rate, and mean arterial pressure. Heart rate responses to dobutamine were similar between groups in both thermal conditions ( P > 0.05). The peak systolic mitral annular velocity (S′), i.e., an index of left ventricular longitudinal systolic function, was similar between groups for both thermal conditions at baseline. While normothermic, the increase in S′ between groups was similar with dobutamine administration. However, while hyperthermic, the increase in S′ was attenuated in the older participants with dobutamine ( P < 0.001). Healthy, older individuals show attenuated inotropic, but maintained chronotropic responsiveness to dobutamine administration during hyperthermia. These data suggest that older individuals have a reduced capacity to increase cardiomyocyte contractility, estimated by changes in S′, via β1-adrenergic mechanisms while hyperthermic.

Exercise training reduces cardiovascular disease risk, partly due to arterial blood pressure (BP) lowering at rest and during fixed-load exercise. However, it is unclear whether exercise training can reduce BP at rest and during exercise in adults with well-healed burn injuries. Therefore, the purpose of this investigation was to test the hypothesis that 6 mo of unsupervised exercise training reduces BP at rest and during lower-body cycle ergometry in adults with well-healed burn injuries. Thirty-nine adults (28 with well-healed burn injuries and 11 controls) completed 6 mo of unsupervised, progressive exercise training including endurance, resistance, and high-intensity interval components. Before and after exercise training, we measured BP at rest, during fixed-load submaximal exercise (50 and 75 W), during fixed-intensity submaximal exercise (40% and 70% of V̇o

Aerobic exercise is important in the rehabilitation of individuals with prior burn injuries, but no studies have examined whether adult burn survivors demonstrate cardiac remodeling to long-term aerobic exercise training. In this study, we tested the hypothesis that 6 months of progressive exercise training would improve cardiac magnetic resonance imaging-based measures of cardiac structure and function in well-healed burn survivors. Our findings highlight the ability of exercise training to modify cardiac structure and function in well-healed burn survivors and nonburned sedentary controls alike.

Hemorrhage is a leading cause of preventable battlefield and civilian trauma deaths. Low-dose (i.e., an analgesic dose) morphine is recommended for use in the prehospital (i.e., field) setting. Morphine administration reduces hemorrhagic tolerance in rodents. However, it is unknown whether morphine impairs autonomic cardiovascular regulation and consequently reduces hemorrhagic tolerance in humans. Thus, the purpose of this study was to test the hypothesis that low-dose morphine reduces hemorrhagic tolerance in conscious humans. Thirty adults (15 women/15 men; 29 ± 6 yr; 26 ± 4 kg·m(−2), means ± SD) completed this randomized, crossover, double-blinded, placebo-controlled trial. One minute after intravenous administration of morphine (5 mg) or placebo (saline), we used a presyncopal limited progressive lower-body negative pressure (LBNP) protocol to determine hemorrhagic tolerance. Hemorrhagic tolerance was quantified as a cumulative stress index (mmHg·min), which was compared between trials using a Wilcoxon matched-pairs signed-rank test. We also compared muscle sympathetic nerve activity (MSNA; microneurography) and beat-to-beat blood pressure (photoplethysmography) during the LBNP test using mixed-effects analyses [time (LBNP stage) × trial]. Median LBNP tolerance was lower during morphine trials (placebo: 692 [473–997] vs. morphine: 385 [251–728] mmHg·min, P < 0.001, CI: −394 to −128). Systolic blood pressure was 8 mmHg lower during moderate central hypovolemia during morphine trials (post hoc P = 0.02; time: P < 0.001, trial: P = 0.13, interaction: P = 0.006). MSNA burst frequency responses were not different between trials (time: P < 0.001, trial: P = 0.80, interaction: P = 0.51). These data demonstrate that low-dose morphine reduces hemorrhagic tolerance in conscious humans. Thus, morphine is not an ideal analgesic for a hemorrhaging individual in the prehospital setting. NEW & NOTEWORTHY In this randomized, crossover, placebo-controlled trial, we found that tolerance to simulated hemorrhage was lower after low-dose morphine administration. Such reductions in hemorrhagic tolerance were observed without differences in MSNA burst frequency responses between morphine and placebo trials. These data, the first to be obtained in conscious humans, demonstrate that low-dose morphine reduces hemorrhagic tolerance. Thus, morphine is not an ideal analgesic for a hemorrhaging individual in the prehospital setting.

Our knowledge about how low-dose (analgesic) morphine affects autonomic cardiovascular regulation is primarily limited to animal experiments. Notably, it is unknown if low-dose morphine affects human autonomic cardiovascular responses during painful stimuli in conscious humans. Therefore, we tested the hypothesis that low-dose morphine reduces perceived pain and subsequent sympathetic and cardiovascular responses in humans during an experimental noxious stimulus. Twenty-nine participants (14 females/15 males; 29 ± 6 yr; 26 ± 4 kg·m(−2), means ± SD) completed this randomized, crossover, placebo-controlled trial during two laboratory visits. During each visit, participants completed a cold pressor test (CPT; hand in ∼0.4°C ice bath for 2 min) before and ∼35 min after drug/placebo administration (5 mg iv morphine or saline). We compared pain perception (100 mm visual analog scale), muscle sympathetic nerve activity (MSNA; microneurography; 14 paired recordings), and beat-to-beat blood pressure (BP; photoplethysmography) between trials (at both pre- and postdrug/placebo time points) using paired, two-tailed t tests. Before drug/placebo infusion, perceived pain (P = 0.92), ΔMSNA burst frequency (n = 14, P = 0.21), and Δmean BP (P = 0.39) during the CPT were not different between trials. After the drug/placebo infusion, morphine versus placebo attenuated perceived pain (morphine: 43 ± 20 vs. placebo: 57 ± 24 mm, P < 0.001) and Δmean BP (morphine: 10 ± 7 vs. placebo: 13 ± 8 mmHg, P = 0.003), but not ΔMSNA burst frequency (morphine: 10 ± 11 vs. placebo: 13 ± 11 bursts·min(−1), P = 0.12), during the CPT. Reductions in pain perception and Δmean BP were only weakly related (r = 0.34, P = 0.07; postmorphine CPT minus postplacebo CPT). These data provide valuable information regarding how low-dose morphine affects autonomic cardiovascular responses during an experimental painful stimulus. NEW & NOTEWORTHY In this randomized, crossover, placebo-controlled trial, we found that low-dose morphine administration reduced pain perception and blood pressure responses during the cold pressor test via attenuated increases in heart rate and cardiac output. We also determined that muscle sympathetic outflow responses during the cold pressor test seem to be unaffected by low-dose morphine administration. Finally, our exploratory analysis suggests that biological sex does not influence morphine-induced antinociception in healthy adults.

The purpose of this study was to evaluate whether burn survivors have lower adherence compared to non-burned control individuals during a 6-month community-based exercise program. In burn survivors we sought to answer if there was a relation between the size of the burn injury and dropout frequency. Fifty-two burn survivors and 15 non-burned controls (n=67) were recruited for a 6-month community-based (i.e., non-supervised), progressive, exercise training program. During the exercise program, 27% (i.e., 4 of 15 enrolled) of the non-burned individuals dropped out of the study, while 37% (i.e., 19 of 52) of the burn survivors dropped out from the study. There was no difference in the percentage of individuals who dropped out between groups (p = 0.552). There was no difference in size of the burn injury, expressed as percent body surface area burned (%BSA) between the burn-survivors that dropped out versus those who completed the exercise regimen (p = 0.951). We did not observe a relation between %BSA burned and dropouts (log odds = -0.15-0.01(%BSA), B= -0.01, SE = 0.015, p = 0.541). There was no effect of %BSA burned on the probability of dropout [Exp (B) = 0.991, 95% CI (0.961, 1.020)] and there were no differences in the percentage of individuals who dropped out of the study based on %BSA burned (χ2(1) = 0.44, p = 0.51). These data demonstrate that burn survivors have similar exercise adherence relative to a non-burned group and the extent of a burn injury does not affect exercise program adherence.

Female adults have a lower tolerance to central hypovolemia, simulated by tilt testing and lower body negative pressure (LBNP; PMID: 26109186). However, the mechanisms responsible for this observation remain unknown. Previous studies investigated sex differences at baseline and presyncope, but the intermediate responses are not fully understood, particularly when expressed as a percentage of tolerance. Therefore, the purpose of this study was to compare autonomic and cardiovascular responses to a simulated hemorrhage between female and male adults at the same relative percentage of their tolerance. We tested the hypothesis that females would have lower blood pressure (BP) and muscle sympathetic nerve activity (MSNA) at the same relative percentage of their tolerance. Eight female (28±8 years old, 171±8 cm, 77±6 kg, BMI: 27±3 kg/m2) and eight male (age: 32±7 years old, height: 178±9 cm, mass: 86±10 kg, BMI: 27±2 kg/m2) adults completed a progressive LBNP protocol that started at -40 mmHg and was further reduced by 10 mmHg every 3 minutes until the participant reached pre-syncope. Presyncope was based on the following criteria: continued reports by the subject of feeling faint and/or nauseous; a rapid decline in blood pressure resulting in systolic blood pressure < 80 mmHg; and/or a relative bradycardia accompanied by narrowing of pulse pressure. LBNP tolerance was quantified as a cumulative stress index (CSI) (mmHg·min) and was compared between sexes using an unpaired t-test. MSNA (microneurography - radial nerve), beat-to-beat blood pressure (BP; Finometer), and heart rate (HR) were obtained at baseline, at 33% and 66% of maximum CSI (60-second averages for both), and the last 30 seconds before 100% CSI (i.e., presyncope). Data were statistically analyzed between the sexes using mixed effects analysis and are presented as mean ± SD. Consistent with prior findings, tolerance to LBNP was lower in females (female: 607±369 vs. male: 960±339 mmHg·min, p = 0.067). There were no differences in systolic, mean, or diastolic BP or HR between the sexes (e.g., main effect of sex, p > 0.199 for all indices) throughout the protocol. MSNA burst frequency (bursts/min) (baseline: 18±8 vs. 25±11; 33% CSI: 30±13 vs. 50±5; 66% CSI: 38±11 vs. 56±4; 100% CSI: 28±10 vs. 40±12; sex: p = 0.004, stage: p < 0.0001, interaction: p = 0.704) and burst incidence (bursts/100 cardiac cycles) (baseline: 29±9 vs. 41±20; 33% CSI: 38±21 vs. 58±10; 66% CSI: 35±18 vs. 52±10; 100% CSI: 32±18 vs. 37±12; sex: p = 0.047, stage: p = 0.022, interaction: p = 0.952) were lower in females than males throughout the protocol, respectively. However, there was no interaction between sexes and relative LBNP stages for MSNA burst frequency or burst incidence. These findings suggest a lack of sex differences in the magnitude of the increase of MSNA throughout LBNP and that lower basal sympathetic activity may be related to reduced tolerance to central hypovolemia. Department of Defense - US Army W81XWH1820012 (CGC) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Approximately 1 million people in the United States are living with multiple sclerosis (MS) with nearly 75% of those being female. MS is a progressive demyelinating neurological disease of the central nervous system associated with a high prevalence of orthostatic hypotension. Our laboratory has previously shown that individuals with MS have a reduced ability to increase mean arterial pressure during simulated hypotension which was attributed to a blunted vascular response. The purpose of this project was to investigate how spontaneous bursts of muscle sympathetic nerve activity (MSNA) induce end-organ response(s) and ultimately evoke a change in blood pressure (BP) on a heartbeat-to-heartbeat basis in females with MS, a process known as sympathetic transduction to BP. We tested the hypothesis that females with MS have reduced resting sympathetic transduction to BP compared to sex-, height-, weight-, age- and race-matched healthy controls. Beat-to-beat BP (Finometer) and MSNA (peroneal microneurography) were continuously recorded during 10 minutes of quiet supine rest in 9 females with relapsing-remitting MS (age: 39.6 ± 3.3 years; Expanded Disability Status Scale < 6.0) and 10 healthy female controls (age: 35.4 ± 2.1 years). Total vascular conductance (TVC) was estimated using modelflow. Sympathetic transduction was determined by identifying the peak change in diastolic BP and the nadir reduction of TVC over 10 cardiac cycles following spontaneous MSNA bursts using signal averaging. No differences were detected in resting mean arterial pressure (MS: 88 ± 3 mmHg; controls: 85 ± 2; P = 0.42) or MSNA burst frequency (MS: 26 ± 3 bursts/min; controls: 19 ± 3 bursts/min; P = 0.11) between groups. Peak increases in diastolic BP following MSNA bursts were lower in females with MS (1.2 ± 0.2 mmHg) compared to controls (2.5 ± 0.6 mmHg; P = 0.039). Whereas no differences were observed in nadir reductions in TVC (MS: -1.7 ± 0.5 ml/min/mmHg; controls: -3.0 ± 0.8 ml/min/mmHg; P = 0.11). These preliminary data suggest that sympathetic transduction to BP is blunted in females with MS. Reduced sympathetic transduction to BP may contribute to the high occurrence of orthostatic hypotension in this clinical population. Further investigation is warranted to help better understand the potential mechanism(s) underlying lower sympathetic transduction in females with MS. This work was supported by American Heart Association Predoctoral Fellowship (Award #915655, Trotter) and American College of Sports Medicine Doctoral Research Grant (Award # 19-01141, Trotter) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Though traditional medicines have been developed through practice for thousands of years, limited research has discussed the research and development (RD) pattern of traditional medicines. China's discovery of artemisinin accumulated valuable experiences to explore traditional medicine under low-resource settings. With limited RD resources, China mobilized all domestic research units at different levels and departments to develop artemisinin collaboratively. The discovery of artemisinin not only based on valuable experiential wisdom of traditional medicine, but also relied on excellent synergy among all units. In this study, we reviewed the story of how artemisinin was discovered in China, summarized key factors for new drug development from traditional medicines under limited resources, and raised suggestions to utilize traditional medicines in low- and middle-income countries. This case suggested that the vitality of traditional medicine could be extended by promoting new drug development based on modern methods and collaboration.

Skin grafting following a burn injury attenuates/abolishes sweat production within grafted areas. It is presently unknown whether the thermoregulatory consequences of skin grafting depend on anatomical location.Purpose: To test the hypothesis that a simulated burn injury on the torso will be no more or less detrimental to core temperature control than on the limbs during uncompensable exercise-heat stress.Methods: Nine non-burned individuals (7 males, 2 females) completed the protocol. On separate occasions, burn injuries of identical surface area (0.45 ± 0.08 m2 or 24.4% ± 4.4% of total body surface area) were simulated on the torso or the arms/legs using an absorbent, vapor-impermeable material that impedes sweat evaporation in those regions. Participants performed 60 min of treadmill walking at 5.3 km·h-1 and a 4.1% ± 0.8% grade, targeting 6 W·kg-1 of metabolic heat production in 40.1°C ± 0.2°C and 19.6% ± 0.6% relative humidity conditions. Rectal temperature, heart rate, and perceptual responses were measured.Results: Rectal temperature increased to a similar extent with simulated injuries on the torso and limbs (condition-by-time interaction: P = 0.86), with a final rectal temperature 0.9 ± 0.3°C above baseline in both conditions. No differences in heart rate, perceived exertion, or thermal sensation were observed between conditions (condition-by-time interactions: P ≥ 0.50).Conclusion: During uncompensable exercise-heat stress, sized-matched simulated burn injuries on the torso or limbs evoke comparable core temperature, heart rate, and perceptual responses, suggesting that the risk of exertional heat illness in such environmental conditions is independent of injury location.

The purpose of this research study was to determine the extent to which quantitative sensory testing (QST) predicted which patients enrolled in an interdisciplinary pain program (IPP) would drop out. Fifty-three patients with chronic pain enrolled in an IPP were assessed before treatment with mechanical and thermal QST at a painful and a non-painful site, as well as with the PROMIS-29 quality of life survey. Pretreatment findings were compared between non-completers (i.e., attended five or fewer sessions for any component of the IPP) and completers. Resulting significant predictors were included in a logistic regression to predict attrition. Compared with those who completed the program, non-completers (24.5%) reported significantly higher pain intensity and oversensitivity to cold at a non-painful site pretreatment, with both variables also predicting completion of the IPP. In summary, these preliminary findings suggest that higher overall pain intensity and the presence of cold oversensitivity (at baseline) may identify patients at risk for dropping out of an IPP.

KEY POINTS Low dose ketamine is a leading medication used to provide analgesia in pre-hospital and hospital settings. Low dose ketamine is increasingly used off-label to treat conditions such as depression. In animals, ketamine stimulates the sympathetic nervous system and increases blood pressure, but these physiological consequences have not been studied in conscious humans. Our data suggest that low dose ketamine administration blunts pain perception and reduces blood pressure, but not muscle sympathetic nerve activity burst frequency, responses during a cold pressor test in healthy humans. These mechanistic, physiological results inform risk-benefit analysis for clinicians administering low dose ketamine in humans. ABSTRACT Low dose ketamine is an effective analgesic medication. However, our knowledge of the effects of ketamine on autonomic cardiovascular regulation is primarily limited to animal experiments. Notably, it is unknown if low dose ketamine influences autonomic cardiovascular responses during painful stimuli in humans. We tested the hypothesis that low dose ketamine blunts perceived pain, and blunts subsequent sympathetic and cardiovascular responses during an experimental noxious stimulus. Twenty-two adults (10F/12M; 27 ± 6 years; 26 ± 3 kg m-2 , mean ± SD) completed this randomized, crossover, placebo-controlled trial during two laboratory visits. During each visit, participants completed cold pressor tests (CPT; hand in ∼0.4°C ice bath for 2 min) pre- and 5 min post-drug administration (20 mg ketamine or saline). We compared pain perception (100 mm visual analogue scale), muscle sympathetic nerve activity (MSNA; microneurography, 12 paired recordings), and beat-to-beat blood pressure (BP; photoplethysmography) during the pre- and post-drug CPTs separately using paired, two-tailed t tests. For the pre-drug CPT, perceived pain (P = 0.4378), MSNA burst frequency responses (P = 0.7375), and mean BP responses (P = 0.6457) were not different between trials. For the post-drug CPT, ketamine compared to placebo administration attenuated perceived pain (P

INTRODUCTION: Although evaporative heat loss capacity is reduced in burn-injured individuals with extensive skin grafts, the thermoregulatory strain due to a prior burn injury during exercise-heat stress may be negligible if the burn is located underneath protective clothing with low vapor permeability. PURPOSE: To test the hypothesis that heat strain during exercise in a hot-dry environment while wearing protective clothing would be similar with and without a simulated torso burn injury. METHODS: Ten healthy individuals (8M/2F) underwent three trials wearing: Uniform (combat uniform, tactical vest, and replica torso armor plates), Uniform with a 20% total body surface area (TBSA) simulated torso burn (Uniform + Burn), or shorts (and sports bra) only (Control). Exercise consisted of treadmill walking (5.3 km·h(–1); 3.7 ± 0.9% grade) for 60 min at a target heat production of 6.0 W·kg(−1) in 40.0 ± 0.1°C; 20.0 ± 0.6% relative humidity conditions. Measurements included rectal temperature, heart rate, rating of perceived exertion, and thermal sensation. RESULTS: No differences in rectal temperature (P ≥ 0.85), heart rate (P ≥ 0.99), thermal sensation (P ≥ 0.73), or rating of perceived exertion (P ≥ 0.13) occurred between Uniform + Burn and Uniform trials. In the Control trial, however, core temperature, heart rate, thermal sensation, and rating of perceived exertion were lower compared to the Uniform and Uniform + Burn trials (P ≤ 0.04 for all). CONCLUSION: A 20% TBSA simulated torso burn injury does not further exacerbate heat strain when wearing a combat uniform. These findings suggest that the physiological strain associated with torso burn injuries is not different from non-injured individuals when wearing protective clothing during an acute exercise-heat stress.

Though studies describe postconcussive changes in eye movements, there is a need for data describing baseline eye movements. The purpose of this study was to describe baseline eye movements and visual contrast acuity using the King-Devick (KD) Eye Tracking System and KD Visual Contrast Sensitivity Chart. Fewer total saccades were noted in soccer players than basketball players (soccer, 56.9 ± 14.3; basketball, 101.1 ± 41.3; p = .0005). No significant differences were noted for the number of saccades between sexes (males, 60.4 ± 20.3; females, 84.9 ± 41.8, p = .100) or in contrast acuity between all groups (p > .05). These results suggest the presence of sport-specific trends that may invalidate the comparison of postconcussion evaluation to generic baseline athlete eye movements.

十二年國民基本教育重視「素養」的學習，在歷史課程中可以透過「歷史思考」的學習加以實踐。臺灣的高中歷史課程關注「歷史思考」已有多年，但十二年國民基本教育才在課程結構上首度提供了具體的實踐機會。推動歷史思考的教學依然需要涵蓋歷史事實，毋須二分切割，但著重歷史思考，更能落實民主社會的理想，培育良好的人與公民。高中生的認知心智發展已經達到形式運思階段，因此學習歷史思考是沒有問題的，真正的挑戰在於教師如何提供適切可行的課程設計，關鍵即在於通盤衡量十二年國民基本教育歷史課程的學分數和學習重點，才有可能讓歷史思考的學習目標實現。 The twelve-year basic education launched in 2019 centers on forging students’ literacy and competencies can be developed and harnessed with the teaching of historical thinking. Historical thinking has long been envisioned in history learning in senior high schools, but the twelve-year curriculum framework makes the implementation of teaching senior high school students historical thinking become something possible and practical. Only when our youngsters are educated with historical thinking together with historical facts can they be shaped into citizens with humanities. The challenge of teaching historical thinking, however, lies not in senior high school students’ cognitive development when they already reach the stage of formal operational, but instead in how history teachers do their curriculum designs. Every curriculum needs to be reviewed, implemented and evaluated. Once the hours of history classes and students’ learning outcomes are addressed in making curriculum mapping complying with the twelve-year curriculum framework, the success of the implementation of historical thinking in history classes can be foreseen in nowaday Taiwan educational context.

Hemorrhage is a leading cause of battlefield and civilian trauma deaths. Several pain medications, including fentanyl, are recommended for use in the prehospital (i.e., field setting) for a hemorrhaging solider. However, it is unknown whether fentanyl impairs arterial blood pressure (BP) regulation, which would compromise hemorrhagic tolerance. Thus, the purpose of this study was to test the hypothesis that an analgesic dose of fentanyl impairs hemorrhagic tolerance in conscious humans. Twenty-eight volunteers (13 females) participated in this double-blinded, randomized, placebo-controlled trial. We conducted a pre-syncopal limited progressive lower-body negative pressure test (LBNP; a validated model to simulate hemorrhage) following intravenous administration of fentanyl (75 µg) or placebo (saline). We quantified tolerance as a cumulative stress index (mmHg•min), which was compared between trials using a paired, two-tailed t test. We also compared muscle sympathetic nerve activity (MSNA; microneurography) and beat-to-beat BP (photoplethysmography) during the LBNP test using a mixed effects model (time [LBNP stage] x trial). LBNP tolerance was not different between trials (Fentanyl: 647 ± 386 vs. Placebo: 676 ± 295 mmHg•min, P = 0.61, Cohen's d = 0.08). Increases in MSNA burst frequency (time: P < 0.01, trial: P = 0.29, interaction: P = 0.94) and reductions in mean BP (time: P < 0.01, trial: P = 0.50, interaction: P = 0.16) during LBNP were not different between trials. These data, the first to be obtained in conscious humans, demonstrate that administration of an analgesic dose of fentanyl does not alter MSNA or BP during profound central hypovolemia, nor does it impair tolerance to this simulated hemorrhagic insult.

Although the severity of a burn injury is often associated with the percentage of total body surface area burned (%TBSA), the thermoregulatory consequences of a given %TBSA injury do not account for the interactive effects of body morphology and metabolic heat production (H(prod)). PURPOSE: Using a simulated burn injury model to mimic the detrimental effect of a 40% TBSA injury on whole-body evaporative heat dissipation, core temperature response to exercise in physiologically uncompensable conditions between morphologically-disparate groups were examined at (i) an absolute H(prod) (watts, W), and (ii) a mass-specific H(prod) (watts per kilogram of body mass, W·kg(−1)). METHODS: Healthy, young, non-burned individuals of small (SM, n = 11) or large (LG, n = 11) body size cycled for 60 min at 500 W or 5.3 W·kg(−1) of H(prod) in 39°C and 20% relative humidity conditions. A 40% burn injury was simulated by affixing a highly absorbent, vapor-impermeable material across the torso (20% TBSA), arms (10% TBSA), and legs (10% TBSA) to impede evaporative heat loss in those regions. RESULTS: While the elevation in core temperature was greater in SM compared to LG at a H(prod) of 500 W (SM: 1.69 ± 0.26°C, LG: 1.05 ± 0.26°C, P < 0.01), elevations in core temperature were not different at a H(prod) of 5.3 W·kg(−1) between groups (SM: 0.99 ± 0.32°C, LG: 1.05 ± 0.26°C, P = 0.66). CONCLUSION: These data suggest that among individuals with a 40% TBSA burn injury, a smaller body size leads to exacerbated elevations in core temperature during physical activities eliciting the same absolute H(prod) (non-weight-bearing tasks) but not activities eliciting the same mass-specific H(prod) (weight-bearing tasks).

There is considerable interindividual variability in the perception of pain. Given that pain management is a major public health problem, gaining insight into the underlying physiology of these perceptual differences is important. We tested the hypothesis that when interindividual variability in initial muscle sympathetic nerve activity (MSNA) responses to a cold pressor test (CPT) is identified, the divergent responses will be linked to differences in pain perception in healthy young men and women. In the supine position, blood pressure (BP) and MSNA were measured at baseline and during a 2-min CPT. Immediately following the CPT, pain was rated (range 0–10). Two groups were established: positive responders (Pos, n = 12) and negative responders (Neg, n = 12) based on the initial (first 30 s) MSNA response profiles (Pos: 12 ± 9, Neg: −3 ± 3 bursts/min, P

Background Interventional exercises have been developed to help athletes improve scores on the Functional Movement Screen™ (FMS™). However, there is a paucity of research on the effects of a similar program in female athletes, as well as the effects of a standardized corrective exercise regimen. The purpose of this study was to assess whether an in-season, standardized interventional exercise program improves FMS™ score asymmetry and the composite score of female collegiate athletes. Study design Prospective, quasi-experimental, cohort study. Methods Forty-one (mean age 19.5 ± 1.2 years; body mass, 70.6 ± 11.5 kg ; height, 1.70 ± 0.083 m) NCAA Division III female soccer (n=10), softball (n=17), and basketball (n=14) players participated in this study. The athletes completed the FMS™ screens prior to their season, regularly participated in four in-season standardized corrective exercises throughout three to four month athletic seasons, and completed the FMS™ screens in the postseason. Results The average score of all athletes before the season was 15.52 ± 0.63 and 16.04 ± 0.72 after the season. While the mean score of soccer players increased from 14.80 ± 0.92 to 16.1 ± 1.52 and the mean score of softball players increased from 15.83 ± 1.89 to 16.72 ± 1.41 at the end of the season, the mean score of basketball players dropped from 15.93 ± 1.49 to 15.29 ± 1.59. Women's basketball players experienced a decrease in their composite FMS™ score ( x ¯ = -0.571, p x ¯ =+1.30, p x ¯ =+1.12, p 0.05). Conclusions Standardized interventional programs during athletic teams' seasons may be used to help increase FMS™ scores and reduce asymmetry. Though more studies are warranted to address the negative effects of this standardized program in women's basketball players, this study demonstrated that the number of asymmetries significantly decreased from pre- to postseason among soccer and softball players, which may have implications for a higher resistance to injury. Levels of evidence 3.

Objective: To examine heart rate variability (HRV) at rest and with a 2-Back cognitive task involving executive function and sustained attention in athletes during the acute phase following concussion and compare them with the controls. Participants: Twenty-three male and female collegiate athletes (20 ± 1 years) following (4 ± 1 days) a sports-related concussion and 23 sports- and sex-matched noninjured controls. Procedure: Continuous R-R interval was acquired using 3-lead electrocardiogram for 3 minutes each at rest and during the 2-Back task. HRV was quantified as percent high-frequency (HF) power. Results: At rest, lower percent HF power was observed in the concussed athletes (23 ± 11) compared with the controls (38 ± 14; P = .0027). However, with the 2-Back task, an increase in HF power was observed in the concussed group (39 ± 12; P = .0008) from rest and was comparable with the controls (36 ± 15). No difference in HF power between rest and 2-Back task was observed in the controls. Conclusion: Lower HRV was observed at rest following concussion. An increase in HRV, suggestive of enhanced prefrontal cortex (PFC) functioning, was observed during a cognitive task in the concussed athletes. Therefore, cognitive tasks as early as 4 days after injury may increase PFC functioning from rest and expedite return to learn in collegiate athletes.

INTRODUCTION. Vasodilator function is impaired in individuals with well-healed burn injuries, but therapeutic interventions that lessen or reverse this maladaptation are lacking. The purpose of this study was to test the hypothesis that a 6-month community-based exercise training program would increase microvascular dilator function in individuals with well healed burn injuries irrespective of the magnitude of the injured body surface area. Further, we hypothesize that macrovascular dilator function would remain unchanged post-training. METHODS. Microvascular function, (forearm reactive hyperemia), macrovascular function (brachial artery flow-mediated dilation), and the maximal vasodilatory response following ischemic handgrip exercise (an estimate of microvascular remodeling) were assessed before and after exercise training in non-burned control subjects (N = 11) and individuals with burn injuries covering a moderate body surface area (26 ± 7 %; N = 13) and a high body surface area (59 ± 15 %; N = 19). RESULTS. Peak vascular conductance and area under the curve during post-occlusive reactive hyperemia increased from pre- to post-training in control and burn injury groups (both P < 0.05), the magnitude of which did not differ between groups (both P = 0.6). Likewise, the maximal vasodilatory response following ischemic handgrip exercise increased in all groups after exercise training (P < 0.05). Macrovascular dilator function did not differ across time or between groups (P = 0.8). CONCLUSION. These data suggest that a community-based exercise training program improves microvascular function in individuals with well-healed burn injuries, which may be due in part to vascular remodeling.