Understanding Orthostatic Intolerance and Exercise Programming for the Health and Fitness Practitioner

The purpose of this manuscript is to briefly review Orthostatic Intolerance (OI) and discuss proper exercise programming and progression guidelines for working with those affected by OI; a disorder associated with autonomic nervous system dysfunction, characterized by a difficulty standing upright. In order to do this, we performed a review of the published literature using google scholar and PubMed search engines. Evidence indicated that a light to moderate intensity aerobic exercise program would aid in improving orthostatic tolerance. Previous studies have indicated that progressive resistance training aids in mechanisms that are dysfunctional in OI such as blood volume increases and a decrease in baroreceptor responses. Preparticipation physical exams and initial value assessments are an integral part of the OI exercise prescription as many individuals will have unhealthy vital capacities due to OI symptomology and accompanying deconditioning. Many Individuals with OI have responded positively to aerobic and resistance training. Using informed judgment when prescribing exercise and careful progression of frequency, intensity, and duration should be considered

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

International Journal of Exercise Science 14(2): 802-814, 2021. The purpose of this study was to examine autonomic modulation using multiple quantitative measures before and after a resistance training (RT) intervention. Seventeen young adults (age 18-35 years) were tested for body composition, muscular strength, and autonomic activity. The RT protocol targeted total-body large muscle groups, which were performed three days a week for eight-weeks. Autonomic assessments included respiratory sinus arrhythmia (RSA), static handgrip exercise, Valsalva maneuver, heart rate variability (HRV), and tilt-table testing. The main finding was that tilt-table duration increased by 68 seconds (p = 0.05) after RT. Upper body strength increased by 11.2 kg (p = 0.001) and lower body strength increased by 68.3 kg (p \u3c 0.001) following completion of the RT intervention. The average total lean mass increased by 1.5 kg (p \u3c 0.01), while total fat mass was unchanged (∆ = 0.5 kg, p = 0.23). RSA (∆ = 0.4, p = 0.89), Valsalva ratio (∆= -0.09, p = 0.48), static handgrip (∆ = 8 mm Hg, p = 0.07), and HRV (∆ = -0.4, p = 0.53) were not affected by RT. The results from this study suggest that RT improves tilt-table tolerance in a young healthy population as evidence by improved tilt-table duration. However, RT seemed to have no effect on cardio-vagal or adrenergic function

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

International Journal of Exercise Science 12(2): 1265-1279, 2019. The purpose of this study was to determine sex differences in the contribution of sensory nerves to rapid cutaneous thermal hyperemia. Healthy young females (n = 15, tested during both the early follicular (EF) and the mid-luteal (ML) phase of the menstrual cycle) and males (n = 15) had a 4 cm2 area of skin on one forearm and one leg treated with a eutectic mixture of local anesthetic (EMLA). EMLA sites, along with corresponding control sites, were instrumented with laser Doppler flowmetry probes and local skin heaters. Baseline (33 °C), rapid and sustained vasodilation (42 °C), and maximal vasodilation (44 °C) skin blood flow data were obtained and expressed as a percentage of maximal cutaneous vascular conductance (%CVCmax). Contribution of sensory nerve involvement was determined by comparing the EMLA site to its matched control site utilizing the formula [(% CVCmax control - % CVCmax treatment) / % CVCmax control] × 100. The contribution of sensory nerves to rapid cutaneous thermal hyperemia in the forearm was 24 ± 18 %CVCmax in males, 41 ± 17 %CVCmax in ML females (p = 0.02 vs. males), and 35 ± 17 %CVCmax in EF females (p \u3e 0.05 vs. males). In the leg, the contribution of sensory nerves was 16 ± 15 %CVCmax in males, 34 ± 17 %CVCmax for ML females (p = 0.02 vs. males), and 28 ± 21 %CVCmax in EF females (p \u3e 0.05 vs. males). ML females exhibited a greater contribution of sensory nerves to rapid cutaneous thermal hyperemia in the forearm and leg, possibly attributed to elevated reproductive hormones during the ML phase

Thermoregulatory Adaptations following Sprint Interval Training

Traditional endurance training typically involves weeks of long-duration (60–90 min) exercise performed at a moderate to vigorous intensity. An alternative paradigm, sprint interval training, is characterized by multiple bouts of short-duration, high-intensity exercise. Similar fitness benefits from the two paradigms have been demonstrated, but whether sprint interval training—like traditional endurance training—induces heat acclimation remains unclear. Purpose To test the hypothesis that sprint interval training performed over six sessions results in measureable thermoregulatory and cardiovascular adaptations consistent with heat acclimation. Methods Seven untrained men [mean ± SD, 13 ± 5% body fat, 22 ± 3 y, 3.1 ± 0.3 L/min peak oxygen uptake (V̇O2peak)] performed 6 sprint interval training sessions over 12 days with 48­–72 h between sessions. Sessions consisted of 4–6 thirty-second Wingate Anaerobic Tests separated by ~4 min. Before and after the two-week training protocol, participants cycled for 30 min at 65% V̇O2peak in 25 °C to assess the effects of sprint interval training on heat acclimation. Results Main outcome variables (onset of sweating, sweat sensitivity, heart rate at end of exercise, percent change in plasma volume, and core temperature change from pre- to post-exercise) were not different from pre- to post-training (all p \u3e 0.05). Conclusion Two weeks of sprint interval training performed under the conditions specified does not result in heat acclimation

Head Trauma not Associated with Long Term Effects on Autonomic Function

International Journal of Exercise Science 14(3): 779-790, 2021. Contact-sports can elicit concussions, which impacts autonomic function, as well as elicit repetitive head trauma, where autonomic function has not yet been assessed. The purpose of this study was to determine if differences in autonomic function exist among three groups (CTRL: healthy non-contact-sport participant, RHT: repetitive head trauma contact-sport participant, CONC: previous concussion). Forty participants (16 men and 24 women), aged 18-37 (22 ± 3), participated in the study. Participants were grouped based on their sport and concussion history (CTRL, RHT, and CONC). Body composition was measured via air displacement plethysmography. Prior to testing, participants were outfitted with equipment to evaluate heart rate, blood pressure, and cerebral-artery blood flow velocity (CBFv). The participant performed against three stimuli: deep breathing, Valsalva maneuver, and a 70° head-up tilt test. Following autonomic function testing, a YMCA submaximal cycle test was performed. All group comparisons were analyzed using a one-way ANOVA and all data are presented as means ± standard deviation. The results of this study indicated that the groups did not differ in respiratory sinus arrhythmia (CTRL: 22 ± 6 bpm, RHT: 21 ± 8 bpm, CONC: 19 ± 7 bpm, p = 0.471), Valsalva ratio (CTRL: 2.19 ± 0.39, RHT: 2.09 ± 0.37, CONC: 2.00 ± 0.47, p = 0.519), CBFv (CTRL: 47.74 ± 25.28 cm/s, RHT: 40.99 ± 10.93 cm/s, CONC: 43.97 ± 17.55 cm/s, p = 0.657), or tilt time (CTRL: 806.09 ± 368.37 sec, RHT: 943.07 ± 339.54 sec, CONC: 978.40 ± 387.98 sec, p = 0.479). However, CONC (113.24 ± 11.64 mmHg) had a significantly higher mean systolic blood pressure during the tilt test than CTRL (102.66 ± 7.79 mmHg, p = 0.026), while RHT (107.9 ± 9.0 mmHg) was not significantly different than CTRL (p = 0.39) or CONC (p = 0.319). The results of this study are the first step in determining if long-lasting deficits to the autonomic nervous system occur following a diagnosis of concussion. However, concussions do not seem to have lasting effects on autonomic function. Overwhelmingly, dysautonomia is not present during chronic recovery from concussions or in individuals with RHT from contact-sports. In the future, sex should be considered as a variable

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Identifying associations between diabetes and acute respiratory distress syndrome in patients with acute hypoxemic respiratory failure: an analysis of the LUNG SAFE database

Background: Diabetes mellitus is a common co-existing disease in the critically ill. Diabetes mellitus may reduce the risk of acute respiratory distress syndrome (ARDS), but data from previous studies are conflicting. The objective of this study was to evaluate associations between pre-existing diabetes mellitus and ARDS in critically ill patients with acute hypoxemic respiratory failure (AHRF). Methods: An ancillary analysis of a global, multi-centre prospective observational study (LUNG SAFE) was undertaken. LUNG SAFE evaluated all patients admitted to an intensive care unit (ICU) over a 4-week period, that required mechanical ventilation and met AHRF criteria. Patients who had their AHRF fully explained by cardiac failure were excluded. Important clinical characteristics were included in a stepwise selection approach (forward and backward selection combined with a significance level of 0.05) to identify a set of independent variables associated with having ARDS at any time, developing ARDS (defined as ARDS occurring after day 2 from meeting AHRF criteria) and with hospital mortality. Furthermore, propensity score analysis was undertaken to account for the differences in baseline characteristics between patients with and without diabetes mellitus, and the association between diabetes mellitus and outcomes of interest was assessed on matched samples. Results: Of the 4107 patients with AHRF included in this study, 3022 (73.6%) patients fulfilled ARDS criteria at admission or developed ARDS during their ICU stay. Diabetes mellitus was a pre-existing co-morbidity in 913 patients (22.2% of patients with AHRF). In multivariable analysis, there was no association between diabetes mellitus and having ARDS (OR 0.93 (0.78-1.11); p = 0.39), developing ARDS late (OR 0.79 (0.54-1.15); p = 0.22), or hospital mortality in patients with ARDS (1.15 (0.93-1.42); p = 0.19). In a matched sample of patients, there was no association between diabetes mellitus and outcomes of interest. Conclusions: In a large, global observational study of patients with AHRF, no association was found between diabetes mellitus and having ARDS, developing ARDS, or outcomes from ARDS. Trial registration: NCT02010073. Registered on 12 December 2013

Association of Variants in the SPTLC1 Gene With Juvenile Amyotrophic Lateral Sclerosis

Importance: Juvenile amyotrophic lateral sclerosis (ALS) is a rare form of ALS characterized by age of symptom onset less than 25 years and a variable presentation.Objective: To identify the genetic variants associated with juvenile ALS.Design, Setting, and Participants: In this multicenter family-based genetic study, trio whole-exome sequencing was performed to identify the disease-associated gene in a case series of unrelated patients diagnosed with juvenile ALS and severe growth retardation. The patients and their family members were enrolled at academic hospitals and a government research facility between March 1, 2016, and March 13, 2020, and were observed until October 1, 2020. Whole-exome sequencing was also performed in a series of patients with juvenile ALS. A total of 66 patients with juvenile ALS and 6258 adult patients with ALS participated in the study. Patients were selected for the study based on their diagnosis, and all eligible participants were enrolled in the study. None of the participants had a family history of neurological disorders, suggesting de novo variants as the underlying genetic mechanism.Main Outcomes and Measures: De novo variants present only in the index case and not in unaffected family members.Results: Trio whole-exome sequencing was performed in 3 patients diagnosed with juvenile ALS and their parents. An additional 63 patients with juvenile ALS and 6258 adult patients with ALS were subsequently screened for variants in the SPTLC1 gene. De novo variants in SPTLC1 (p.Ala20Ser in 2 patients and p.Ser331Tyr in 1 patient) were identified in 3 unrelated patients diagnosed with juvenile ALS and failure to thrive. A fourth variant (p.Leu39del) was identified in a patient with juvenile ALS where parental DNA was unavailable. Variants in this gene have been previously shown to be associated with autosomal-dominant hereditary sensory autonomic neuropathy, type 1A, by disrupting an essential enzyme complex in the sphingolipid synthesis pathway.Conclusions and Relevance: These data broaden the phenotype associated with SPTLC1 and suggest that patients presenting with juvenile ALS should be screened for variants in this gene.</p

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

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

Body mass index (BMI) has been used for years by clinicians to approximate total body fat. However, the body adiposity index (BAI), body adiposity index from the FELS longitudinal study (BAIFELS), and an equation developed by Deurenberg et al. (BFD) were created recently to offset BMI’s limitations and accurately estimate percent body fat (%BF). The prevalence of overweight and obese Caucasian men is increasing in the United States; currently, there is no established way to quickly and accurately predict their %BF. Purpose: To compare the existing %BF equations (BAI, BAIFELS, and BFD) to measured %BF via air displacement plethysmography (ADP) in order to determine the most accurate way to predict %BF in overweight and obese Caucasian men. Methods: Four hundred and fifty-two Caucasian men aged from 18 to 76, with a BMI of 25.0 to 42.4 kg/m2, participated in this study. Height, weight, waist circumference, hip circumference, and body composition using ADP were measured on each participant. These measurements were inserted into the three equations to determine any differences between the equations and the actual %BF measured by ADP. Results: Differences in %BF between ADP and the BAI (p \u3c 0.001) and ADP and the BAIFELS (p \u3c 0.001) were discovered. While no differences (p = 1.00) between ADP and BFD existed. Conclusion: In a population of overweight and obese Caucasian adults from the United States, the BAI and BAIFELS are not appropriate to predict %BF while the BFD prediction equation proved worthy of consideration