A non-volitional skeletal muscle endurance test measures functional changes associated with impaired blood flow.

Introduction: An electrically stimulated intermittent fatigue test using mechanomyography was recently proposed as a possible tool for detecting clinically relevant changes in muscle function. This study was designed to determine whether the proposed test can detect additional fatigue when it should be present. Methods: Subjects (n = 10) underwent two trials each (occluded and normal blood flow) with a standardized fatigue protocol on the Ankle Dorsiflexors (AD) and Wrist Extensors (WE) using a clinical electrical stimulator. Results: Mean normalized twitch acceleration was strongly predictive of mean normalized torque (R 2 = 0.828). The WE experienced lower twitch magnitudes throughout the tourniquet trial (10.81 ± 1.25 m/s2) compared to normal blood flow (18.05 ± 1.06 m/s2). The AD twitches were overall reduced in the tourniquet trial (3.87 ± 0.48 m/s2) compared with the control trial (8.57 ± 0.91 m/s2). Conclusion: Occluding blood flow to a muscle should cause greater muscle fatigue. The ability to detect reduced contraction magnitudes during an electrically stimulated fatigue protocol resulting from low blood flow suggests the proposed test may be capable of detecting clinically relevant muscle deficits.

2021 Year in Review: E-Cigarettes, Hookah Use, and Vaping Lung Injuries During the COVID-19 Pandemic.

Electronic cigarettes (e-cigarettes) and hookah smoking have gained tremendous popularity over the past decade. With the constantly evolving e-cigarette market and potential impact of the COVID-19 pandemic on users of these tobacco products, research is needed to assess the prevalence and safety of these devices as well as potential public health implications and cessation tools. For this year in review, PubMed was searched from January 2021-December 14, 2021, for articles related to e-cigarettes, vaping-related lung injury, and hookah smoking. Relevant articles addressing the objectives were included in this review. This review focused primarily on articles based on United States populations. Gray literature and nonpublished articles were not included in this review. The 2020 pandemic resulted in a decline in e-cigarette usage among youth (potentially due to the COVID-19 pandemic); however, recent research in 2021 suggests that e-cigarette usage is increasing again among youth. Conflicting evidence exists for e-cigarettes and the risk of COVID-19 infection, but biological plausibility suggests that e-cigarette users are more susceptible to COVID-19 infection and more severe COVID-19 infection compared to non-e-cigarette users. Hookah smoking has remained stable across the past several years and remains a primarily social activity among youth. New e-cigarette devices are constantly emerging, resulting in an increased demand to understand the safety of these devices. Additionally, hookah smoking continues to be a concerning public health issue with the increase in hookah bars and venues coupled with lack of policy regulations for hookah smoking.

Substance use and deaths by suicide: A latent class analysis of the National Violent Death Reporting System.

Substance use is strongly associated with suicide completions. However, little is known about the patterns of substances used in suicide deaths. The purpose of this analysis is to determine latent classes of toxicology-reported substances among individuals who completed suicide. The sample consists of suicide victims in the National Violent Death Reporting System (NVDRS) during years 2003-2017 (n = 202,838). Toxicology reports were used to construct latent class analyses of substance use among suicide victims. Correlates for latent class membership included sex, race/ethnicity, previous experiences of child abuse, homelessness, and intimate partner violence (IPV) victimization. The majority of suicide victims were male (77.7%), straight/heterosexual (99.5%) and white (88.3%). The final unconditional model yielded a four-class model, including a "No substance/single substance use" class, an "Alcohol and other substance" class, a "Marijuana and other substance" class, and an "Opiate use" class. Compared to the reference class of "No substance/single substance," females were more likely than males to be classified in the "Alcohol and other substance" class, the "Multi-substance use" class, and the "Opiate use" class. Homelessness was associated with classification in the "Marijuana and other substance" class and the "Opiate use" class compared to the "No substance/single substance" class. IPV was associated with both polysubstance use classes ("Alcohol plus other substance" and "Marijuana plus other substance") along with the "Opiate use" class compared to the "No substance/single substance" class. These classes highlight profiles of suicide descendants and emphasize the importance of polysubstance use prevention among females, homeless individuals, and those who experience IPV.

Dual Use of Electronic Cigarettes and Traditional Cigarettes Among Adults: Psychosocial Correlates and Associated Respiratory Symptoms.

BACKGROUND: Prolonged use of both electronic cigarettes (e-cigarettes) and traditional cigarettes can increase breathing difficulties and other adverse health effects. Research is needed to provide a deeper understanding of predictors of dual use, particularly given rapid changes in the e-cigarette market and related public health communications and policy. METHODS: The sample consists of subjects in the National Longitudinal Study of Adolescent to Adult Health Wave 5 (cross-sectional) subsample (N = 3,800) from 2016 to 2018. Participants were 31-42 y old. Multinomial logistic regression analyses were used to determine predictors of mutually exclusive categories: e-cigarette use only, cigarette use only, and concurrent e-cigarette and traditional cigarette use (compared to no use). Predictors included sex, age, poverty status, race/ethnicity, self-reported diagnosed depression, self-reported diagnosed anxiety, and previous experience of child maltreatment. RESULTS: Among the total sample (N = 3,800), 2% reported e-cigarette use only, 20% reported traditional cigarette use only, and 3% reported dual use of both e-cigarettes and traditional cigarettes. Among subjects who reported any e-cigarette or traditional cigarette use (n = 957), 12% reported dual use. In the final adjusted multivariable multinomial model, dual use was associated with living at or below the poverty line (odds ratio 2.49 [95% CI 1.19-5.70]), self-reported diagnosed depression (odds ratio 1.99 [95% CI 1.10-3.61]), and a history of child maltreatment (odds ratio 1.80 [95% CI 1.10-2.95]). Additionally, Hispanic-American individuals were more likely to report dual use compared to cigarette-only use. CONCLUSIONS: Prolonged dual use of both e-cigarettes and traditional cigarettes is a considerable public health problem. While our study identified a low percentage of dual usage among U.S. adults, dual use was disproportionately prevalent among those with depression, history of child maltreatment, living at or below the poverty line, and among Hispanic-American individuals. Culturally appropriate interventions and increasing access to cessation programs may help mitigate health disparities pertaining to dual use.

Downhill Running Impairs Activation and Strength of the Elbow Flexors.

ABSTRACT: Brandenberger, KJ, Warren, GL, Ingalls, CP, Otis, JS, and Doyle, JA. Downhill running impairs activation and strength of the elbow flexors. J Strength Cond Res 35(8): 2145-2150, 2021-The purpose of this study was to determine if knee extensor injury induced by 1 hour of downhill running attenuated force production in the elbow flexors. Subjects completed either downhill running for 1 hour (injured group; n = 6) or sedentary behavior (control group; n = 6). Strength and voluntary activation (%VA) were measured by isometric twitch interpolation of the elbow flexor and knee extensor muscles at the following time points in relation to the injury: before injury (Pre), after injury (Post), 24 hours after injury (24Post), and 48 hours after injury (48Post). Mean (±SE) knee extensor strength was significantly reduced (53.5 ± 9.9%) Post and remained reduced at 24Post and 48Post in the injury group. Knee extensor muscle twitch strength was reduced Post and 24Post after the downhill run (p < 0.022). Elbow flexor muscle strength was significantly reduced Post (13.2 ± 3.9%) and 24Post (17.3 ± 4.0%). Elbow flexor muscle twitch strength was not significantly different at any time point. Elbow flexor muscle %VA was not significantly reduced compared with Pre, at Post (16.2 ± 5.1%), 24Post (20.9 ± 6.7%), or 48Post (12.9 ± 4.5%). A 1-hour downhill run significantly injured the knee extensors. The elbow flexor muscles remained uninjured, but strength of these muscles was impaired by reduced %VA. These data suggest muscle injury can lead to prolonged strength deficits in muscles distant from the injury and should be accounted for when scheduling training that may lead to delayed-onset muscle soreness.

A retrospective analysis of associations between BMI and days spent on mechanical ventilation in a level 1 trauma facility.

OBJECTIVE: To examine whether BMI impacts the outcomes of mechanically ventilated patients. METHODS: Data was collected retrospectively among patients involved in motor vehicle accidents in intensive care at a major trauma center in Atlanta, GA. Patients were categorized into five BMI groups: underweight (BMI < 18.5), normal weight (BMI of 18.5-24.9), overweight (BMI of 25-29.9), obese (BMI of 30-39.9), and morbidly obese (BMI of >40). RESULTS: Among all patients (n=2,802), 3% of patients were underweight, 34% were of normal weight, 30% were overweight, 27% were obese, and 6% were morbidly obese. The mean number of ventilator days for normal weight patients was 4.6, whereas the mean number of ventilator days for underweight and morbidly obese patients were higher (10.3 and 7.4, respectively). CONCLUSIONS: Underweight and morbidly obese populations may require additional interventions during their ICU stays to address the challenges presented by having an unhealthy BMI.

Consumption of a 5-mg Melatonin Supplement Does Not Affect 32.2-km Cycling Time Trial Performance.

Brandenberger, KJ, Ingalls, CP, Rupp, JC, and Doyle, JA. Consumption of a 5-mg melatonin supplement does not affect 32.2-km cycling time trial performance. J Strength Cond Res 32(10): 2872-2877, 2018-Some studies suggest that exogenous melatonin supplementation may improve athletic performance in hot humid environments because of its precooling effect. However, melatonin is also consumed as a sleep aid for its depressive effects on the central nervous system (CNS), which may hinder performance. Therefore, this study was conducted to determine whether consuming a 5-mg supplement of melatonin would affect performance in a laboratory-simulated 32.2-km cycling time trial. The time trial was conducted in a thermoneutral environment to separate CNS depressive effects of the melatonin from the cooling effects. Trained male subjects (n = 10; V[Combining Dot Above]O2max = 62.7 ± 6.3 ml·kg·min; age = 25.1 ± 4.0 years; mass = 69.9 ± 9.1 kg; height = 176.0 ± 7.1 cm) performed three 32.2-km time trials on an electronically braked cycle ergometer. The first trial was a familiarization. During the 2 experimental trials, subjects received in a random order either a placebo or a 5-mg melatonin supplement 15 minutes before exercise in a double-blind, crossover design. Variables were measured before exercise and at 8-km intervals. The mean 32.2-km time trial completion times for the melatonin (64.94 ± 5.95 minutes) and placebo (65.26 ± 6.85 minutes) trials were not different (p = 0.682). The mean time trial power output for the melatonin (190.4 ± 40.4 watts) and placebo (190.0 ± 45.7 watts) trials was not different (p = 0.927). Rectal temperature was not significantly different for melatonin compared with placebo (p = 0.827). These results suggest that a 5-mg melatonin supplement administered 15 minutes before exercise does not measurably impact the performance of a 32.2-km cycling time trial in a thermoneutral environment.