Development of a prediction equation to estimate lower-limb arterial occlusion pressure with a thigh sphygmomanometer.

INTRODUCTION: Previous investigators have developed prediction equations to estimate arterial occlusion pressure (AOP) for blood flow restriction (BFR) exercise. Most equations have not been validated and are designed for use with expensive cuff systems. Thus, their implementation is limited for practitioners. PURPOSE: To develop and validate an equation to predict AOP in the lower limbs when applying an 18 cm wide thigh sphygmomanometer (SPHYG18cm). METHODS: Healthy adults (n = 143) underwent measures of thigh circumference (TC), skinfold thickness (ST), and estimated muscle cross-sectional area (CSA) along with brachial and femoral systolic (SBP) and diastolic (DBP) blood pressure. Lower-limb AOP was assessed in a seated position at the posterior tibial artery (Doppler ultrasound) using a SPHYG18cm. Hierarchical linear regression models were used to determine predictors of AOP. The best set of predictors was used to construct a prediction equation to estimate AOP. Performance of the equation was evaluated and internally validated using bootstrap resampling. RESULTS: Models containing measures of either TC or thigh composition (ST and CSA) paired with brachial blood pressures explained the most variability in AOP (54%) with brachial SBP accounting for majority of explained variability. A prediction equation including TC, brachial SBP, and age showed good predictability (R2 = 0.54, RMSE = 7.18 mmHg) and excellent calibration. Mean difference between observed and predicted values was 0.0 mmHg and 95% Limits of Agreement were ± 18.35 mmHg. Internal validation revealed small differences between apparent and optimism adjusted performance measures, suggesting good generalizability. CONCLUSION: This prediction equation for use with a SPHYG18cm provided a valid way to estimate lower-limb AOP without expensive equipment.

Blood flow restriction as a potential therapy to restore physical function following COVID-19 infection.

Accumulating evidence indicates that some COVID-19 survivors display reduced muscle mass, muscle strength, and aerobic capacity, which contribute to impairments in physical function that can persist for months after the acute phase of illness. Accordingly, strategies to restore muscle mass, muscle strength, and aerobic capacity following infection are critical to mitigate the long-term consequences of COVID-19. Blood flow restriction (BFR), which involves the application of mechanical compression to the limbs, presents a promising therapy that could be utilized throughout different phases of COVID-19 illness. Specifically, we hypothesize that: 1) use of passive BFR modalities can mitigate losses of muscle mass and muscle strength that occur during acute infection and 2) exercise with BFR can serve as an effective alternative to high-intensity exercise without BFR for regaining muscle mass, muscle strength, and aerobic capacity during convalescence. The various applications of BFR may also serve as a targeted therapy to address the underlying pathophysiology of COVID-19 and provide benefits to the musculoskeletal system as well as other organ systems affected by the disease. Consequently, we present a theoretical framework with which BFR could be implemented throughout the progression from acute illness to outpatient rehabilitation with the goal of improving short- and long-term outcomes in COVID-19 survivors. We envision that this paper will encourage discussion and consideration among researchers and clinicians of the potential therapeutic benefits of BFR to treat not only COVID-19 but similar pathologies and cases of acute critical illness.

Effects of Single-Session Meditation on Aortic Pulsatility and Anxiety in Mildly to Moderately Anxious Adults.

Context: Anxiety is a common mental health concern in the USA that is associated with an increased risk of hypertension, arterial stiffness, and cardiovascular disease. Therapists have used eight-week programs for mindfulness meditation to treat anxiety; however little is known about the psychophysiological effects of a single meditation session. Objective: The study intended to assess the effects of a one-hour, mindfulness-meditation session on anxiety symptomology and cardiovascular function, including aortic pulsatility. Design: The research team performed a prospective, single-group study. Setting: The study took place at Michigan Technological University. Participants: Participants were 14 young adults with an initial Beck Anxiety Inventory (BAI) score of 8 to 26, showing mild to moderate anxiety. Intervention: Participants took part in a single, one-hour, guided, mindfulness-meditation session. Outcome Measures: The research team: (1) administered the BAI during an orientation session and at 60-minutes post intervention, and (2) measured the cardiovascular variables of qualified participants at the orientation, at baseline prior to the intervention, immediately post intervention, and at 60 minutes post intervention, including systolic arterial blood pressure (SAP), diastolic arterial blood pressure (DAP), heart rate (HR), aortic pulse pressure (aPP), aortic pulsatility, aortic augmentation index (AIx) at 75 bpm, carotid-radial pulse wave velocity (crPWV), carotid-femoral pulse wave velocity (cfPWV), and respiratory rate. Results: Participants had a significant decrease in the BAI scores between baseline and 60-minutes post intervention (P = .01) and a significant reduction in aortic pulsatility-aPP x HR-between baseline and immediately post intervention and between baseline and 60-minutes post intervention (both P < .01). Conclusions: Preliminary results suggest that one hour of introductory mindfulness meditation can have both psychological and cardiovascular benefits for anxious individuals.

Blood pressure and muscle sympathetic nerve activity are associated with trait anxiety in humans.

Chronic anxiety is prevalent and associated with an increased risk of cardiovascular disease. Prior studies that have reported a relationship between muscle sympathetic nerve activity (MSNA) and anxiety have focused on participants with anxiety disorders and/or metabolic syndrome. The present study leverages a large cohort of healthy adults devoid of cardiometabolic disorders to examine the hypothesis that trait anxiety severity is positively associated with resting MSNA and blood pressure. Resting blood pressure (BP) (sphygmomanometer and finger plethysmography), MSNA (microneurography), and heart rate (HR; electrocardiogram) were collected in 88 healthy participants (52 males, 36 females, 25 ± 1 yr, 25 ± 1 kg/m2). Multiple linear regression was performed to assess the independent relationship between trait anxiety, MSNA, resting BP, and HR while controlling for age and sex. Trait anxiety was significantly correlated with systolic arterial pressure (SAP; r = 0.251, P = 0.018), diastolic arterial pressure (DAP; r = 0.291, P = 0.006), mean arterial pressure (MAP; r = 0.328, P = 0.002), MSNA burst frequency (BF; r = 0.237, P = 0.026), and MSNA burst incidence (BI; r = 0.225, P = 0.035). When controlling for the effects of age and sex, trait anxiety was independently associated with SAP (ß = 0.206, P = 0.028), DAP (ß = 0.317, P = 0.002), MAP (ß = 0.325, P = 0.001), MSNA BF (ß = 0.227, P = 0.030), and MSNA BI (ß = 0.214, P = 0.038). Trait anxiety is associated with increased blood pressure and MSNA, demonstrating an important relationship between anxiety and autonomic blood pressure regulation.NEW & NOTEWORTHY Anxiety is associated with development of cardiovascular disease. Although the sympathetic nervous system is a likely mediator of this relationship, populations with chronic anxiety have shown little, if any, alteration in resting levels of directly recorded muscle sympathetic nerve activity (MSNA). The present study is the first to reveal an independent relationship between trait anxiety, resting blood pressure, and MSNA in a large cohort of healthy males and females devoid of cardiometabolic comorbidities.

Post-Exercise Arterial Stiffness Responses Are Similar After Acute Eccentric and Concentric Arm Cycling.

Upper-body resistance exercise effectively increases muscular strength, but may concomitantly increase arterial stiffness. Eccentric exercise can lead to muscle soreness and arterial stiffness in untrained participants. However, it is unclear if upper-body eccentric exercise could reduce arterial stiffness in a single session for participants that have undergone progressive training. Our purpose was to compare acute responses to upper-body eccentric (novel, ECCarm) and concentric (traditional, CONarm) steady state arm cycling. We hypothesized that arm arterial stiffness would be reduced after both ECCarm and CONarm. Twenty-two young healthy individuals performed either ECCarm (n = 11) or CONarm (n = 11) at ~70% of peak heart rate for 20 min after a training period. Heart rate, central pulse wave velocity (cPWV), and peripheral pulse wave velocity (pPWV; i.e., arm arterial stiffness) were assessed before, 10 min, and 30 min after exercise. Heart rate was not elevated at 10 min post ECCarm, but was elevated at 10- and 30-min post CONarm (p < 0.01). After exercise, pPWV was decreased at 10 min post for both ECCarm (7.1 ± 0.3 vs. 6.5 ± 0.2 m/s) and CONarm (7.0 ± 0.2 vs. 6.5 ± 0.2 m/s; p < 0.05), while both groups returned to baseline values 30 min post. cPWV did not change in either group. Our results indicate that acute ECCarm provides a high-force, low energy cost form of resistance exercise that acutely reduces arm arterial stiffness. The reduction in pPWV and rapid heart rate recovery suggests that ECCarm is a safe form of exercise for overall and cardiovascular health.

An experiential learning course for cardiovascular and sleep technology.

Undergraduate programs related to allied health are often pursued by students to prepare for entrance into professional programs, but many students also ask about what types of employment options they may have upon completion of the bachelor's degree. This experiential learning course in cardiovascular and sleep technology was designed to provide opportunities for students to gain hands-on clinical skills that could help them to enter professional programs or to find employment in an allied health field such as cardiopulmonary rehabilitation, cardiovascular technology, or sleep technology. The prerequisites for this course were the completion of two semesters of anatomy and physiology. This course was based on experiential learning and was structured into three modules: clinical exercise physiology, autonomic physiology, and sleep physiology. As part of the course students completed a 4-page scientific report for one designated topic within each of the modules. The two exams in the course were essay based. The design of this course required students to review key topics from anatomy and physiology, to comprehend peer-reviewed manuscripts, to gain hands-on experiences with sophisticated physiological equipment, to work as individuals and in groups, and to become better oral and written communicators. The sleep physiology module included an introduction to electroencephalography (EEG) and a student-led nap study, which may be an effective way to introduce students to sleep medicine. We are hopeful that the summary of this course will be useful to physiology educators as they work to provide the most meaningful experiences to their undergraduates in the health sciences.NEW & NOTEWORTHY Experiential learning in clinical exercise, autonomic regulation, and sleep physiology is an impactful way to train undergraduate biomedical students to enter a variety of careers in healthcare, graduate programs in the health professions, or traditional research graduate programs. A hands-on course such as Cardiovascular and Sleep Technology provides a way, in addition to or independent of original research, to provide clinically relevant training.

Evening binge alcohol disrupts cardiovagal tone and baroreflex function during polysomnographic sleep.

STUDY OBJECTIVES: Binge alcohol consumption is associated with increased cardiovascular risk. The effects of evening binge alcohol consumption (i.e. 4-5 beverages within 2 h) on the vagal components of HRV and cardiovagal baroreflex sensitivity (cvBRS) during sleep remain largely equivocal. The present study examined the effects of evening binge alcohol consumption on nocturnal cardiac vagal tone and baroreflex sensitivity during stage N2, slow wave (SWS), and rapid eye movement (REM) sleep. We hypothesized that evening binge drinking would reduce HRV and cvBRS in each sleep stage. METHODS: Following a familiarization night within the laboratory, twenty-three participants were examined following a night of binge alcohol consumption and a fluid control (randomized, crossover design). A quality nocturnal beat-to-beat blood pressure signal was obtained in both conditions in 16 participants (seven men, nine women; 25 ± 1 years). RESULTS: Binge drinking reduced both the high frequency (HF) and time-domain components (i.e. pNN50 and RMSSD) of HRV in stage N2 sleep, SWS, and REM. In addition, cvBRS up-up (vagal activation) was reduced following binge alcohol consumption in stage N2 (21 ± 3 vs. 15 ± 3 ms/mmHg, p = 0.035) and REM (15[11-28] vs. 11[9-18] ms/mmHg, p = 0.009). Binge alcohol consumption reduced cvBRS down-down (vagal withdrawal) in stage N2 (23 ± 2 vs. 14 ± 2 ms/mmHg, p < 0.001), SWS (20[14-30] vs. 14[9-17] ms/mmHg, p = 0.022), and REM (14[11-24] vs. 10[7-15] ms/mmHg, p = 0.006). CONCLUSIONS: Evening binge alcohol consumption disrupts cardiac vagal tone and baroreflex function during nearly all sleep stages. These findings provide mechanistic insight into the potential role of binge drinking and alcohol abuse on cardiovascular risk. CLINICAL TRIALS DETAILS: Alcohol and Neural Cardiovascular Control in Binge Drinkers, www.clinicaltrials.gov/ct2/show/NCT03567434, NCT03567434.

Morning sympathetic activity after evening binge alcohol consumption.

Binge alcohol consumption elicits acute and robust increases of muscle sympathetic nerve activity (MSNA), yet the impact of evening binge drinking on morning-after MSNA is unknown. The present study examined the effects of evening binge alcohol consumption on polysomnographic sleep and morning-after MSNA. We hypothesized that evening binge drinking (i.e. 4-5 drink equivalent in <2 h) would reduce sleep quality and increase morning-after blood pressure (BP) and MSNA. Following a familiarization night within the sleep laboratory, 22 participants (12 men, 10 women; 25 ± 1 yr) were examined after simulated binge drinking or fluid control (randomized, crossover design). Morning MSNA was successfully recorded across both conditions in 16 participants (8 men, 8 women) during a 10-min baseline and three Valsalva's maneuvers (VM). Binge drinking reduced rapid eye movement (REM) sleep (15 ± 1 vs. 20 ± 1%, P = 0.003), increased stage II sleep (54 ± 1 vs. 51 ± 1%, P = 0.002), and increased total urine output (2.9 ± 0.2 vs. 2.1 ± 0.1 liters, P < 0.001) but did not alter morning-after urine specific gravity. Binge drinking increased morning-after heart rate [65 (54-72) vs. 58 (51-67) beats/min, P = 0.013] but not resting BP or MSNA. Binge drinking elicited greater sympathoexcitation during VM (38 ± 3 vs. 43 ± 3 bursts/min, P = 0.036). Binge drinking augmented heart rate (P = 0.002), systolic BP (P = 0.022), and diastolic BP (P = 0.037) reactivity to VM phase IV and blunted cardiovagal baroreflex sensitivity during VM phases II (P = 0.028) and IV (P = 0.043). In conclusion, evening binge alcohol consumption disrupted REM sleep and morning-after autonomic function. These findings provide new mechanistic insight into the potential role of binge drinking on cardiovascular risk.NEW & NOTEWORTHY Chronic binge alcohol consumption is associated with future cardiovascular disease (CVD) risk in both men and women. In addition, binge alcohol consumption is known to disrupt normal sleep quality during the early morning hours, coinciding with the morning sympathetic surge. In the present study, an evening of binge alcohol consumption increased baseline morning heart rate and cardiovascular reactivity during the Valsalva maneuver (VM) strain. Specifically, muscle sympathetic nerve activity and phase IV hemodynamic responses increased during VM the morning after binge alcohol consumption. The autonomic dysfunction and increased cardiovascular reactivity during VM suggests a contributing mechanism to CVD risk present in individuals who binge drink.

Moving student research forward during the COVID-19 pandemic.

The COVID--19 pandemic has impacted undergraduate and graduate student research. With the uncertainty right now, it is a challenge for faculty to offer clear guidance for how students can proceed with their research and capstone projects. In this brief editorial, we offer suggestions for moving student research forward during the COVID-19 pandemic.

Chronic Standing Desk Use and Arterial Stiffness.

BACKGROUND: Sedentary activity and sitting for at least 10 hours per day can increase the risk for cardiovascular disease by more than 60%. Use of standing desks may decrease sedentary time and improve cardiovascular health. Acute standing lowers pulse wave velocity (PWV), but chronic effects remain unknown. The purpose of this study was to determine the effect of chronic standing desk use on arterial stiffness versus seated controls. METHODS: A total of 48 adults participated in this study. Twenty-four participants qualified as seated desk users (age 41 [10] y, body mass index 25 [4] kg/m2) and 24 as standing desk users (age 45 [12] y, body mass index 25 [5] kg/m2). Arterial stiffness was assessed as PWV within the aorta, arm, and leg. RESULTS: Carotid-femoral PWV (cfPWV) was not different between seated (6.6 [1.3] m/s) and standing (6.9 [1.3] m/s) groups (P = .47). Similarly, there were no differences in arm or leg PWV between groups (P = .13 and P = .66, respectively). A secondary analysis of traditional factors of age and aerobic fitness revealed significant differences in cfPWV in seated and standing desk participants. Age also significantly influenced cfPWV across conditions. CONCLUSIONS: Standing for >50% of a workday did not affect PWV. Consistent with previous research, fitness and age are important modulators of arterial stiffness.

The relationship of high-intensity cross-training with arterial stiffness.

BACKGROUND: Central arterial stiffness is a cardiovascular risk factor that can be readily affected through engagement in physical exercise training, with resistance and aerobic exercise having disparate affects. Despite the growing popularity of high-intensity cross-training (HICT), little is currently known about the effects of this mixed modality exercise stimulus on arterial stiffness. Therefore, the purpose of this study was to characterize the arterial stiffness of habitual HICT participants vs. aerobically active and sedentary controls using a cross-sectional design. METHODS: A total of 30 participants were recruited: 10 middle-aged long-term participants of HICT (CrossFit) and 20 age, sex, and height matched controls (10 recreationally active, 10 sedentary). Central and peripheral pulse wave velocities were measured for the carotid-femoral and femoral-dorsalis pedis arterial segments. Aerobic fitness (maximal oxygen uptake, VO2max) was measured and typical exercise participation rates were self-reported for each group. RESULTS: HICT participants manifested central pulse wave velocity (PWV) (5.3 ± 1.0 m/s, mean ± SD) and VO2max (43 ± 6 mL/kg/min) values nearly identical to active controls. Both active groups had significantly better values than sedentary controls (7.1 ± 1.0 m/s, p ≤ 0.001; and 32 ± 7 mL/kg/min, p = 0.01). No differences were observed in peripheral PWV between groups. CONCLUSION: Habitual participation in HICT exercise was not associated with increased central nor peripheral arterial stiffness. Long-term HICT participants presented with similar fitness and arterial stiffness as compared with participants who practiced traditional aerobic exercise. Compared to sedentary living, HICT may offer musculoskeletal and cardiovascular health benefits without negatively impacting arterial stiffness.

Does persistent snowpack inhibit degradation of fecal stress indicators?

Physiological stress in wildlife can be a useful indicator of a population's response to environmental factors. By using non-invasive endocrinological techniques, such as fecal sampling, potential confounding factors associated with the stress of capture can be avoided. A potential drawback of fecal sampling, however, is degradation of samples which may produce aberrant measurements of fecal glucocorticoid metabolites. In vertebrates, glucocorticoids, such as corticosterone, become elevated in response to stress. We sought to gauge the reliability of measurement of fecal glucocorticoid metabolites from white-tailed deer (Odocoileus virginianus) fecal samples exposed to a temperate winter with substantial snow cover and cold temperatures for up to 90 days, by repeatedly subsampling fecal samples every 10 days and performing a corticosterone enzyme-linked immunosorbent assay (ELISA). Measurements of fecal glucocorticoid metabolites at 10 days were consistent with initial measurements, after which (20 days) they became aberrant following a period of thawing. Consequently, glucocorticoid metabolite levels in feces appear to remain stable under ambient conditions if temperatures remain below freezing at least for 10 days. While it's possible that samples may remain useful beyond this time frame based on previous laboratory studies of samples stored in a freezer, further work is needed to determine how samples weather in situ under extreme cold (e.g. Arctic) or periods of partial thawing.

Chronic eccentric arm cycling improves maximum upper-body strength and power.

INTRODUCTION: Eccentric leg cycling (cycle ergometry adapted to impose muscle lengthening contractions) offers an effective exercise for restoring lower-body muscular function, maintaining health, and improving performance in clinical and athletic populations. PURPOSE: We extended this model to the upper body and evaluated the effectiveness of a 7-week eccentric arm cycling (ECCarm) intervention to improve upper-body muscular function. We also explored whether ECCarm would alter arterial function. METHODS: Participants performed ECCarm (n = 9) or concentric arm cycling (CONarm; n = 8) 3×/week while training intensity increased (5-20 min, 60-70% upper-body peak heart rate). Maximum elbow extensor strength, upper-body concentric power, and peripheral and central arterial stiffness were assessed before and after training. RESULTS: During training, heart rates and perceived exertion did not differ between groups (~68% upper-body peak heart rate, ~12 Borg units, both P > 0.05), whereas power during ECCarm was ~2× that for CONarm (122 ± 43 vs. 59 ± 20 W, P < 0.01). Muscle soreness for ECCarm was greater than CONarm (P = 0.02), however, soreness was minimal for both groups (<0.50 cm). Following training, ECCarm exhibited greater changes in elbow extensor strength (16 ± 10 vs. 1 ± 9%, P = 0.01) and upper-body power (6 ± 8 vs. -3 ± 7%, P < 0.01) compared to CONarm. Peripheral and central arterial stiffness did not change for either group (both P > 0.05). CONCLUSION: Upper-body eccentric exercise improved dynamic muscular function while training at low exertion levels. Results occurred with minimal soreness and without compromising arterial function. ECCarm findings parallel eccentric leg cycling findings and indicate that eccentric cycle ergometry offers a robust model for enhancing upper-body muscular function. ECCarm could have applications in rehabilitation and sport training.

Cerebral Blood Flow Velocity During Combined Lower Body Negative Pressure and Cognitive Stress.

BACKGROUND: Lower body negative pressure (LBNP) decreases middle cerebral artery blood velocity (MCAv) and can induce hypotension. Mental stress increases MCAv, but the MCAv response to combined LBNP and mental stress (COMBO) is unknown. We hypothesized that performing a stressful cognitive challenge (i.e., mental stress) concurrently with LBNP would prevent LBNP-induced reductions of MCAv. METHODS: There were 18 subjects (9 men, 9 women; ages 20.1±0.3 yr) who completed 3 randomized 3-min trials: 1) LBNP (-40 mmHg); 2) mental stress (serial subtraction); and 3) COMBO (LBNP+mental stress). All reported values are mean±SE. Mean arterial pressure (MAP), heart rate (HR), forearm blood flow (FBF), and MCAv were measured continuously. Subjects also reported perceived stress following the mental stress and COMBO trials. RESULTS: LBNP decreased MAP (Δ-1.4±0.5 mmHg), MCAv (Δ-2.6±1.1 cm s(-1)) and FBF (Δ-0.8±0.1 units), and increased HR (Δ2.7±1.2 bpm). Mental stress increased MAP (Δ10.1±1.3 mmHg), HR (Δ17.4±2.2 bpm), and FBF (Δ2.4±0.4 units), while MCAv (Δ2.8±1.3 cm s(-1)) tended to increase. COMBO increased MAP (Δ5.3±2.3 mmHg) and HR (Δ21.3±2.6 bpm), and tended to increase FBF (Δ0.5±0.3 units). However, MCAv (Δ-4.6±2.0 cm s(-1)) decreased during COMBO. Decreases in MCAv during COMBO were not statistically different from LBNP-induced decreases (Δ-4.6±2.0 vs. Δ-2.6±1.1 cm s(-1)). Subjective ratings of perceived stress (standard 0 to 4 scale) tended to be higher during COMBO than mental stress (2.9±0.1 vs. 2.5±0.1 units). CONCLUSION: Our results suggest that mental stress does not effectively preserve MCAv when combined with central hypovolemia (i.e., LBNP).

Injury Risk Estimation Expertise: Assessing the ACL Injury Risk Estimation Quiz.

BACKGROUND: Available methods for screening anterior cruciate ligament (ACL) injury risk are effective but limited in application as they generally rely on expensive and time-consuming biomechanical movement analysis. A potentially efficient alternative to biomechanical screening is skilled movement analysis via visual inspection (ie, having experts estimate injury risk factors based on observations of athletes' movements). PURPOSE: To develop a brief, valid psychometric assessment of ACL injury risk factor estimation skill: the ACL Injury Risk Estimation Quiz (ACL-IQ). STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: A total of 660 individuals participated in various stages of the study, including athletes, physicians, physical therapists, athletic trainers, exercise science researchers/students, and members of the general public in the United States. The ACL-IQ was fully computerized and made available online (www.ACL-IQ.org). Item sampling/reduction, reliability analysis, cross-validation, and convergent/discriminant validity analyses were conducted to refine the efficiency and validity of the assessment. RESULTS: Psychometric optimization techniques identified a short (mean time, 2 min 24 s), robust, 5-item assessment with high reliability (test-retest: r = 0.90) and high test sensitivity (average difference of exercise science professionals vs general population: Cohen d = 2). Exercise science professionals and individuals from the general population scored 74% and 53% correct, respectively. Convergent and discriminant validity was demonstrated. Scores on the ACL-IQ were best predicted by ACL knowledge and specific judgment strategies (ie, cue use) and were largely unrelated to domain-general spatial/decision-making ability, personality, or other demographic variables. Overall, 23% of the total sample (40% of exercise science professionals; 6% of general population) performed better than or equal to the ACL nomogram. CONCLUSION: This study presents the results of a systematic approach to assess individual differences in ACL injury risk factor estimation skill; the assessment approach is efficient (ie, it can be completed in <3 min) and psychometrically robust. The results provide evidence that some individuals have the ability to visually estimate ACL injury risk factors more accurately than other instrument-based ACL risk estimation methods (ie, ACL nomogram). The ACL-IQ provides the foundation for assessing the efficacy of observational ACL injury risk factor assessment (ie, does simple skilled visual inspection reduce ACL injuries?). The ACL-IQ can also be used to increase our understanding of the perceptual-cognitive mechanisms underlying injury risk assessment expertise, which can be leveraged to accelerate learning and improve performance.

Role of the ovarian cycle on neural cardiovascular control in sleep-deprived women.

The midluteal (ML) phase of the ovarian cycle is often sympathoexcitatory compared with the early follicular (EF) phase. We recently reported that 24-h total sleep deprivation (TSD) augmented cardiovascular reactivity in both men and women, but that sex differences existed in resting muscle sympathetic nerve activity (MSNA) responses to TSD. In the present study, we hypothesized increased resting MSNA and augmented cardiovascular reactivity to acute laboratory stressors during the ML phase in sleep-deprived women. Heart rate (HR), mean arterial pressure (MAP), forearm vascular conductance (FVC), and MSNA were measured in 14 eumenorrheic women (age, 20 ± 1 yr) during 10 min supine rest, 5 min mental stress (MS) trial, and 2 min cold pressor test (CPT) trial. Subjects were tested twice after TSD: once during EF phase and once during ML phase (randomized, crossover design). Estradiol (29 ± 2 vs. 63 ± 8 pg/ml, P = 0.001) and progesterone (1.6 ± 0.2 vs. 4.4 ± 0.7 ng/ml, P = 0.002) were elevated during the ML phase. Resting supine MAP (75 ± 2 vs. 72 ± 1 mmHg, P = 0.042) was lower during the ML phase. In contrast, resting supine HR, MSNA, and FVC were not significantly different between EF and ML phases. MAP, HR and FVC reactivity to MS were not statistically different between the EF and ML phases. Similarly, MAP and HR reactivity to CPT were not different between the ovarian phases. Contrary to our original hypothesis, the ML phase was not associated with sympathoexcitation or exaggerated cardiovascular reactivity in sleep-deprived premenopausal women. However, our data reveal elevated resting blood pressure during the EF phase in sleep-deprived women.