Inertial Load Power Cycling Training Increases Muscle Mass and Aerobic Power in Older Adults.

PURPOSE: Reductions in skeletal muscle mass, beginning after the third decade of life, reduce maximal neuromuscular power (Pmax). Maximal aerobic power generation is also reduced. The primary purpose of this study was to investigate the effectiveness of maximal power cycling (PC) training using an inertial load ergometer on skeletal muscle mass and cardiovascular function in untrained 50- to 68-yr-old participants. METHODS: The study used a pre- or postoutcome exercise intervention testing untrained 50- to 68-yr-old adults (n = 39, M = 15, mean ± SE = 58.5 ± 0.8, range = 50-68 yr). Over the course of 8 wk, participants performed 15 min of training 3 times per week. Each session involved repeated (15-30 times) 4-s sprints of PC. Measurements were thigh muscle volume, total body lean mass, Pmax, peak oxygen consumption, cardio-ankle vascular index, performance on functional tests of living (FTLChair and FTLRamp), and intermuscular fat volume. RESULTS: Training for 8 wk increased thigh muscle volume (3.7% ± 0.9%, P < 0.001) and total body lean mass (1.5% ± 0.4%, P < 0.01) while increasing total body mass (TBM) (1.4% ± 0.3%, P < 0.01). Physical performance measures increased significantly (all P < 0.05) with improvements in Pmax (12.0% ± 1.5%); peak oxygen consumption (9.8% ± 1.8%), and FTL (8.5% ± 1.3% to 17.2% ± 2%). Cardio-ankle vascular index was significantly decreased -2.3% ± 1.1% (P < 0.05), indicating reduced arterial stiffness. CONCLUSIONS: These results demonstrate that 8 wk of PC training at true maximal power was effective at increasing muscle mass and maximal power, as well as maximal cardiovascular capacity and functional tasks in untrained 50- to 68-yr-olds.

Emotion Regulation in Elementary School-Aged Children with a Maternal History of Suicidal Behavior: A Pilot Study.

Parental history of suicidal behavior is associated with an increased risk of early onset suicidal behavior in their offspring. The objective of this pilot study was to compare clinical characteristics, temperament, and emotion regulation in children, aged 6-9 years, with (PH+) and without (PH-) a maternal history of suicidal behavior to determine which factors could be markers of early vulnerability. At baseline, PH+ children, compared to PH- children, demonstrated more difficulties with temperament, emotion regulation, and experienced more life events in the year prior to their baseline appointment. At study follow-ups, however, no differences were found between PH+ and PH- children. Results suggest there are some signals of early vulnerability present in children with a maternal history of suicidal behavior and recruitment/retention of this group of youth is feasible.

A Surgical Mouse Model for Advancing Laryngeal Nerve Regeneration Strategies.

Iatrogenic recurrent laryngeal nerve (RLN) injury is a morbid complication of anterior neck surgical procedures. Existing treatments are predominantly symptomatic, ranging from behavioral therapy to a variety of surgical approaches. Though laryngeal reinnervation strategies often provide muscle tone to the paralyzed vocal fold (VF), which may improve outcomes, there is no clinical intervention that reliably restores true physiologic VF movement. Moreover, existing interventions neglect the full cascade of molecular events that affect the entire neuromuscular pathway after RLN injury, including the intrinsic laryngeal muscles, synaptic connections within the central nervous system, and laryngeal nerve anastomoses. Systematic investigations of this pathway are essential to develop better RLN regenerative strategies. Our aim was to develop a translational mouse model for this purpose, which will permit longitudinal investigations of the pathophysiology of iatrogenic RLN injury and potential therapeutic interventions. C57BL/6J mice were divided into four surgical transection groups (unilateral RLN, n = 10; bilateral RLN, n = 2; unilateral SLN, n = 10; bilateral SLN, n = 10) and a sham surgical group (n = 10). Miniaturized transoral laryngoscopy was used to assess VF mobility over time, and swallowing was assessed using serial videofluoroscopy. Histological assays were conducted 3 months post-surgery for anatomical investigation of the larynx and laryngeal nerves. Eight additional mice underwent unilateral RLN crush injury, half of which received intraoperative vagal nerve stimulation (iVNS). These 8 mice underwent weekly transoral laryngoscopy to investigate VF recovery patterns. Unilateral RLN injury resulted in chronic VF immobility but only acute dysphagia. Bilateral RLN injury caused intraoperative asphyxiation and death. VF mobility was unaffected by SLN transection (unilateral or bilateral), and dysphagia (transient) was evident only after bilateral SLN transection. The sham surgery group retained normal VF mobility and swallow function. Mice that underwent RLN crush injury and iVNS treatment demonstrated accelerated and improved VF recovery. We successfully developed a mouse model of iatrogenic RLN injury with impaired VF mobility and swallowing function that can serve as a clinically relevant platform to develop translational neuroregenerative strategies for RLN injury.

Low Stroke Volume during Exercise with Hot Skin Is Due to Elevated Heart Rate.

It is well known that hyperthermia lowers stroke volume (SV) during moderate-intensity prolonged exercise, yet the underlying mechanism is inconclusive, especially when skin temperature (Tsk) is hot (≥38°C). PURPOSE: In the present study, HR was independently lowered by a low dose of ß1-blockade (ßB) to investigate its effect on SV during exercise when skin is hot. The effect of rapid skin cooling on reversing cardiovascular responses was also examined. METHODS: Nine men cycled at 62% V˙O2peak wearing a water-perfused suit for 20 min during three conditions: (a) moderate Tsk (~33°C) (MOD), (b) hot Tsk (~38°C) (HOT), and (c) hot Tsk (38°C) with ßB (HOT-ßB). Skin temperature was then rapidly cooled at 20 min in all trials by cold water (0°C-2°C) perfusion while subjects continued cycling for another 20 min. RESULTS: When HR was lowered during HOT-ßB (152 ± 4 bpm) to the same level as MOD (150 ± 4 bpm; P = 0.30), SV in HOT-ßB (132 ± 8 mL) was also restored to the same level as MOD (129 ± 7 mL, P = 0.37) even with a significantly higher cutaneous blood flow (CBF) and lower mean arterial blood pressure. When Tsk was rapidly cooled, cardiac output, HR, and CBF significantly decreased while SV remained lower in HOT. Forearm venous volume was not different between trials during heating and cooling. CONCLUSIONS: The increase in HR rather than an increase in CBF or forearm venous volume was responsible for the decrease in SV during moderate-intensity exercise when Tsk was held at 38°C.

Cardiovascular responses to exercise when increasing skin temperature with narrowing of the core-to-skin temperature gradient.

The decline in stroke volume (SV) during exercise in the heat has been attributed to either an increase in cutaneous blood flow (CBF) that reduces venous return or an increase in heart rate (HR) that reduces cardiac filling time. However, the evidence supporting each mechanism arises under experimental conditions with different skin temperatures (Tsk; e.g., ≥38°C vs. ≤36°C, respectively). We systematically studied cardiovascular responses to progressively increased Tsk (32°C-39°C) with narrowing of the core-to-skin gradient during moderate intensity exercise. Eight men cycled at 63 ± 1% peak oxygen consumption for 20-30 min. Tsk was manipulated by having subjects wear a water-perfused suit that covered most of the body and maintained Tsk that was significantly different between trials and averaged 32.4 ± 0.2, 35.5 ± 0.1, 37.5 ± 0.1, and 39.5 ± 0.1°C, respectively. The graded heating of Tsk ultimately produced a graded elevation of esophageal temperature (Tes) at the end of exercise. Incrementally increasing Tsk resulted in a graded increase in HR and a graded decrease in SV. CBF reached a similar average plateau value in all trials when Tes was above ~38°C, independent of Tsk. Tsk had no apparent effect on forearm venous volume (FVV). In conclusion, the CBF and FVV responses suggest no further pooling of blood in the skin when Tsk is increased from 32.4°C to 39.5°C. The decrease in SV during moderate intensity exercise when heating the skin to high levels appears related to an increase in HR and not an increase in CBF. NEW & NOTEWORTHY This study systematically investigated the effect of increasing skin temperature (Tsk) to high levels on cardiovascular responses during moderate intensity exercise. We conclude that the declines in stroke volume were related to the increases in heart rate but not the changes in cutaneous blood flow (CBF) and forearm venous volume (FVV) during moderate intensity exercise when Tsk increased from ~32°C to ~39°C. High Tsk (≥38°C) did not further elevate CBF and FVV compared with lower Tsk during moderate intensity exercise.

Prescription Opioid Exposures Among Children and Adolescents in the United States: 2000-2015.

OBJECTIVES: This study analyzes and compares exposures to prescription opioids among children and adolescents younger than 20 years old in the United States. METHODS: Data from the National Poison Data System for 2000 through 2015 were analyzed. RESULTS: Poison control centers received reports of 188 468 prescription opioid exposures among children aged <20 years old from 2000 through 2015. The annual number and rate of exposures increased early in the study period, but declined after 2009, except for buprenorphine exposures, which increased during the last 3 study years. Hydrocodone accounted for the largest proportion of exposures (28.7%), and 47.1% of children exposed to buprenorphine were admitted to a health care facility (HCF). The odds of being admitted to an HCF were higher for teenagers than for children aged 0 to 5 years (odds ratio [OR]: 2.86; 95% confidence interval [CI]: 2.78-2.94) or children aged 6 to 12 years (OR: 6.62; 95% CI: 6.06-7.02). Teenagers also had greater odds of serious medical outcomes than did children aged 0 to 5 years (OR: 3.03; 95% CI: 2.92-3.15) or children aged 6 to 12 years (OR: 4.59; 95% CI: 4.21-5.00). The rate of prescription opioid-related suspected suicides among teenagers increased by 52.7% during the study period. CONCLUSIONS: Prescription opioid-related HCF admissions and serious medical outcomes were higher among teenagers. Contrary to trends for other prescription opioids, exposures to buprenorphine have increased in recent years; children aged 0 to 5 years accounted for almost 90% of buprenorphine exposures. These findings indicate that additional prevention efforts are needed.