Placebo Exercise Research Articles

Acetaminophen influences musculoskeletal signaling but not adaptations to endurance exercise training.

Acetaminophen (ACE) is a widely used analgesic and antipyretic drug with various applications, from pain relief to fever reduction. Recent studies have reported equivocal effects of habitual ACE intake on exercise performance, muscle growth, and risks to bone health. Thus, this study aimed to assess the impact of a 6-week, low-dose ACE regimen on muscle and bone adaptations in exercising and non-exercising rats. Nine-week-old Wistar rats (n = 40) were randomized to an exercise or control (no exercise) condition with ACE or without (placebo). For the exercise condition, rats ran 5 days per week for 6 weeks at a 5% incline for 2 min at 15 cm/s, 2 min at 20 cm/s, and 26 min at 25 cm/s. A human equivalent dose of ACE was administered (379 mg/kg body weight) in drinking water and adjusted each week based on body weight. Food, water intake, and body weight were measured daily. At the beginning of week 6, animals in the exercise group completed a maximal treadmill test. At the end of week 6, rats were euthanized, and muscle cross-sectional area (CSA), fiber type, and signaling pathways were measured. Additionally, three-point bending and microcomputer tomography were measured in the femur. Follow-up experiments in human primary muscle cells were used to explore supra-physiological effects of ACE. Data were analyzed using a two-way ANOVA for treatment (ACE or placebo) and condition (exercise or non-exercise) for all animal outcomes. Data for cell culture experiments were analyzed via ANOVA. If omnibus significance was found in either ANOVA, a post hoc analysis was completed, and a Tukey's adjustment was used. ACE did not alter body weight, water intake, food intake, or treadmill performance (p > .05). There was a treatment-by-condition effect for Young's Modulus where placebo exercise was significantly lower than placebo control (p < .05). There was no treatment by condition effects for microCT measures, muscle CSA, fiber type, or mRNA expression. Phosphorylated-AMPK was significantly increased with exercise (p < .05) and this was attenuated with ACE treatment. Furthermore, phospho-4EBP1 was depressed in the exercise group compared to the control (p < .05) and increased in the ACE control and ACE exercise group compared to placebo exercise (p < .05). A low dose of ACE did not influence chronic musculoskeletal adaptations in exercising rodents but acutely attenuated AMPK phosphorylation and 4EBP1 dephosphorylation post-exercise.

Incobotulinumtoxin A and Yoga-like Isometric Exercise in Adolescent Idiopathic Lumbar Scoliosis—A Randomized Pilot Study

Background: Approximately 90% of scoliosis cases are adolescent-idiopathic (AIS). From the first appearance of scoliosis at 10–14 years of age until the age of 18, the spine is most vulnerable to deterioration; young, growing people are most susceptible to the worsening of one or more scoliotic curves. An effective non-surgical means of remediation would be welcome. Design: This was a randomized, controlled, two-arm study assessing the safety and efficacy of combining incobotulinum injections with yoga to reverse lumbar and thoracolumbar AIS. Methods: In a private clinic setting, non-pregnant, healthy 12–18 year-olds were either taught a symmetrical “placebo” yoga pose (control sub-group 1), performed the side plank (Vasisthasana) three times daily with a placebo injection (control sub-group 2) or performed the three-times-daily side plank with a botulinum injection (intervention group 3). Injection: For the injection, 33 IU of incobotulinumtoxin type A (Xeomin) was injected into the concave-side lumbar paraspinals and quadratus lumborum at L2–3 and the psoas muscle at L3–4, or participants were injected similarly with a placebo. Randomization was achieved using random.org. Objective: The objective was to determine whether the treatment of muscular asymmetry with botulinum toxin injections and side planks is safe and effective in AIS. Results/Outcome: Eleven intervention and thirteen placebo patients (Groups 1 + 2), who were 12–18 years old, completed the three-month study. Mean daily side plank time = 165 s. The mean initial lumbar curvature was 36.9 degrees (SD 14.36), (p &lt; 0.0001); the mean Group 3 curvature at 3 weeks was 29.5 degrees (SD 14.23) (p &lt; 0.0001); and the mean Group 3 curvature at 3 months was 26.0 degrees (SD 12.81). Onset vs. 3-month value: p &lt; 0.0001. Harms were limited to one patient in Group 2 and one in Group 3, who complained of transient shoulder pain and supported themselves temporarily on their forearm instead of the palm of the extended hand. Conclusion: Muscle strength asymmetry appears to be relevant to AIS treatment. Incobotulinum injections combined with side planks performed with the convex side downward may be more effective in reversing lumbar AIS than placebo exercises or side planks and placebo injections.

Effects of Exercise on Functional Recovery in Patients with Bipolar Depression: A Study Protocol for a Randomized Controlled Trial.

Treatment of bipolar disorder is prone to prolongation despite various treatments, including medication. The efficacy of exercise treatment (i.e., interventions involving physical exercise and sports intervention) for major depressive disorders has been reported for depressive symptoms, cognitive function, and sleep disturbances. However, its efficacy for bipolar disorder has yet to be established. We designed a randomized, controlled, double-blind clinical trial that includes 100 patients with bipolar disorder aged 20-65 years. This will be a cluster-randomized, two-group trial that will be conducted in ten psychiatric hospitals. The hospitals will be randomly assigned to an exercise intervention + treatment as usual (exercise) group or a placebo exercise intervention (stretching) + treatment as usual (control) group. Patients will be assessed using an extensive battery of clinical tests, physical parameters, sleep status, biological parameters (cytokines, neurotrophic factors), and genetic parameters (DNA and RNA) at baseline after a 6-week intervention period, at 10-week follow-up, and at 6-month follow-up. This innovative study may provide important evidence for the effectiveness of exercise in the treatment of bipolar depression based on clinical, biological, genetic, and physiological markers.

Does the internet help the unemployed find jobs?

This study examines the effect of internet job search (IJS) on job-finding rates among unemployed job seekers during the rapid expansion of the internet from the mid-1990s to the early 2010s. To address endogenous selection into IJS, I use an instrumental variables (IV) strategy exploiting the rise of IJS within occupations over time, which varied across occupations depending on pre-internet exposure to computers at work. The analysis sample includes unemployed workers from the December 1998, August 2000, September 2001, October 2003, and July 2011 Current Population Survey (CPS) Computer and Internet Use Supplements and the September 1992 Basic Monthly CPS, longitudinally matched with their employment outcomes from the subsequent monthly CPS files. The IV estimates indicate that IJS increased the 15-month job-finding rate by 12.9 percentage points (25.1% relative to the mean). Results from placebo exercises and various specification checks support a causal interpretation of the estimated effects. Additionally, the effectiveness of IJS remained stable over time throughout the analysis period.

Effects of Aerobic Exercise Concurrent with Caffeine Supplementation on Weight and Body Fat Among Overweight Women

Background: Obesity and overweight are among serious global epidemics that significantly threaten human health, especially among women. Objectives: This study aimed to assess the concurrent effects of 6-week caffeine supplementation with moderate-intensity aerobic exercise on weight and body fat among overweight women. Methods: Thirty overweight females (age: 36.47 ± 6.48 years; BMI: 27.61 ± 1.54 kg/m2; mean ± SD) with a sedentary lifestyle were recruited to the study. The participants were randomly allocated to the experimental group, EC (exercise + caffeine) group, who took 100 milligrams of caffeine of the “API” brand supplement 30 minutes before exercise training (n = 15) or control group, EP (exercise + placebo) (n = 15). All participants performed moderate-intensity aerobic exercise with an intensity of 40 to 60% of heart rate reserve based on the individual's exercise test for 30 minutes, three days a week for six weeks. Measurements, including the percentage of body fat, waist circumference, and skinfold (suprailiac, abdominal), were done two times, at baseline and after six weeks of exercising. Results: There were no significant differences between control and experimental groups related to weight (P = 0.22), percentage body fat (P = 0.88), and other measurements after six weeks. Conclusions: 6 weeks of caffeine supplementation combined with moderate-intensity aerobic exercise without dietary interventions couldn’t make a significant reduction in weight and central or total body fat among overweight women.

Long-term effect of full-body pulsed electromagnetic field and exercise protocol in the treatment of men with osteopenia or osteoporosis: A randomized placebo-controlled trial

Background: Osteoporosis is the most prevalent metabolic disease affecting bones. Objective: To investigate the long-term effect of pulsed electromagnetic field (PEMF) combined with exercise protocol on bone mineral density (BMD) and bone markers in men with osteopenia or osteoporosis. Methods: Ninety-five males with osteopenia or osteoporosis (mean age, 51.26 ± 2.41 years; mean height, 176 ± 2.02 cm; mean weight, 83.08 ± 2.60 kg; mean body–mass index (BMI), 26.08 ± 1.09 kg/m2) participated in the study, and they were randomly assigned to one of three groups: Group 1 received a full-body PEMF and exercise protocol (PEMF +EX), Group 2 received a placebo full-body PEMF and exercise protocol (PPEMF +EX), and Group 3 received a full-body PEMF alone (PEMF). PEMF was applied for the whole body using a full-body mat three times per week for 12 weeks, with an exercise protocol that includes flexibility, aerobic exercise, strengthening, weight-bearing, and balance exercises followed by whole-body vibration (WBV) training. Outcome measures include BMD of total hip and lumbar spine and bone markers [serum osteocalcin (s-OC), Serum amino-terminal cross-linking telopeptide of type I collagen (s-NTX), Serum carboxy-terminal cross-linking telopeptide of type I collagen (s-CTX), Parathyroid hormones (PTH), Bone-specific Alkaline Phosphatase (BSAP), and 25-hydroxy vitamin D (Vit D)]. Results: The BMD of total hip and lumbar spine was significantly increased post-treatment in all groups, and more so in Group 1 and Group 2 than Group 3. There was a significant difference in bone markers in all groups, more so in Group 1 and Group 2 than in Group 3. Conclusion: PEMF combined with exercise protocol exerts a potent role for treating OP, is more effective than exercise and PEMF alone for increasing BMD and enhancing bone formation, and suppresses bone-resorption markers after 12-weeks of treatment with the impact lasting up to 6 months.

Effects of Sling-Based Thoracic Active Exercise on Pain and Function and Quality of Life in Female Patients with Neck Pain: A Randomized Controlled Trial

This study aimed to investigate the effects of sling-based thoracic active exercise on pain, function, and quality of life in female patients with neck pain. A total of 27 female patients with neck pain were divided into the sling-based thoracic active exercise group (n = 14) and the control group (n = 13). The study group performed a sling-based thoracic active exercise with cervical manual therapy for 50 min a day, twice a week for 4 weeks, whereas the control group performed a placebo exercise with cervical manual therapy in the same manner as the study group. Evaluation of the degree of pain before and after treatment was based on the pressure pain threshold and numeric pain rating scale scores. The craniovertebral angle and neck disability index (NDI) were used to evaluate neck function, and quality of life was measured using the Short Form-36. Afterwards, the patients’ pressure pain thresholds were significantly increased, and the numeric pain rating scale score was significantly decreased in both groups (p < 0.05). In terms of function, the craniovertebral angle was significantly increased in both groups (p < 0.05), and neck dysfunction significantly decreased (p < 0.05). The quality of life significantly increased in both groups (p < 0.05). The pressure pain threshold, craniovertebral angle, neck dysfunction index, and quality of life scores (p < 0.05) were significantly different between groups, except the numeric pain scale score. Our results showed that sling-based thoracic active exercise is effective in reducing pain and improving function and quality of life in female patients with neck pain, thus emphasizing the need for thoracic treatment for such patients.

Long-term effect of full-body pulsed electromagnetic field and exercise protocol in the treatment of men with osteopenia or osteoporosis: A randomized placebo-controlled trial

Background: Osteoporosis is the most prevalent metabolic disease affecting bones. Objective: To investigate the long-term effect of pulsed electromagnetic field (PEMF) combined with exercise protocol on bone mineral density (BMD) and bone markers in men with osteopenia or osteoporosis. Methods: Ninety-five males with osteopenia or osteoporosis (mean age, 51.26 ± 2.41 years; mean height, 176 ± 2.02 cm; mean weight, 83.08 ± 2.60 kg; mean body–mass index (BMI), 26.08 ± 1.09 kg/m2) participated in the study, and they were randomly assigned to one of three groups: Group 1 received a full-body PEMF and exercise protocol (PEMF +EX), Group 2 received a placebo full-body PEMF and exercise protocol (PPEMF +EX), and Group 3 received a full-body PEMF alone (PEMF). PEMF was applied for the whole body using a full-body mat three times per week for 12 weeks, with an exercise protocol that includes flexibility, aerobic exercise, strengthening, weight-bearing, and balance exercises followed by whole-body vibration (WBV) training. Outcome measures include BMD of total hip and lumbar spine and bone markers [serum osteocalcin (s-OC), Serum amino-terminal cross-linking telopeptide of type I collagen (s-NTX), Serum carboxy-terminal cross-linking telopeptide of type I collagen (s-CTX), Parathyroid hormones (PTH), Bone-specific Alkaline Phosphatase (BSAP), and 25-hydroxy vitamin D (Vit D)]. Results: The BMD of total hip and lumbar spine was significantly increased post-treatment in all groups, and more so in Group 1 and Group 2 than Group 3. There was a significant difference in bone markers in all groups, more so in Group 1 and Group 2 than in Group 3. Conclusion: PEMF combined with exercise protocol exerts a potent role for treating OP, is more effective than exercise and PEMF alone for increasing BMD and enhancing bone formation, and suppresses bone-resorption markers after 12-weeks of treatment with the impact lasting up to 6 months.

Pilot study testing the emotional response to physical exercise following a negative emotional induction in adults with borderline personality disorder

IntroductionPhysical exercise is a well-documented treatment for individuals with mental disorder. It helps improve symptoms and functioning of these individuals. Moreover, recent studies indicated that exercise improve emotional regulation which is one of the main target in borderline personality disorder (BPD) treatment. Therefore, exercise might have important benefits in this population. However, no previous study examined this effect.ObjectivesThis pilot study documents the facceptability of a protocol testing the effects of exercise on the response to a negative emotion in adults with BPD.Methods28 adults with a diagnosis of BPD have been recruited in a psychiatric hospital. Participants filled several questionnaires then viewed a scene from Silence of the Lambs to induce negative emotions. They were then assigned to 20 minutes of exercise or a neutral video of 20 minutes. Affects were assessed 7 times during the protocol.ResultsIn this sample, 9 participants reported at least equal levels of affect after the induction than before. Preliminary results show a tendency of higher response of physical exercise than control on positive affects and no participant had any adverse effect from exercise.ConclusionsThis pilot study was the first to test the effects of exercise on symptoms of BPD. It also informs on the best way to conduct the principal study. First, the mood induction was poor, thus it will be changed for a stronger induction strategy. Then, the control intervention will be a placebo exercise. These modifications will enable a better understanding of the effects of exercise on emotion regulation with BPD population.

Effectiveness of Mulligan manual therapy over exercise on headache frequency, intensity and disability for patients with migraine, tension-type headache and cervicogenic headache \u2013 a protocol of a pragmatic randomized controlled trial

BackgroundNon - pharmacological management of migraine, tension-type headache (TTH), and cervicogenic headache (CGH) may include spinal manual therapy and exercise. Mulligan Manual Therapy (MMT) utilizes a protocol of headache elimination procedures to manage headache parameters and associated disability, but has only been evaluated in CGH. There is little evidence for its effectiveness in migraine and TTH. This study aims to determine the effectiveness of MMT and exercise over exercise and placebo in the management of migraine, TTH, and CGH.MethodsThis pragmatic trial is designed as a prospective, three-armed randomised controlled trial in a clinical setting provided at a general hospital physiotherapy department. Two hundred ninety-seven participants with a diagnosis of migraine, TTH or CGH based on published headache classification guidelines will be included. An assessor blind to group allocation will measure outcomes pre-and post-intervention as well as 3 and 6 months after commencement of treatment. Participants will be allocated to one of the three groups: MMT and exercise; placebo and exercise; and exercise alone. The primary outcome measure is headache frequency. Secondary outcome measures are headache duration and intensity, medication intake, pressure pain threshold (PPT), range of motion recorded with the flexion rotation test, and headache disability recorded with Headache Activities of Daily Living Index (HADLI). The intention-to-treat principle will be followed for statistical analysis. Between groups differences for all outcome measures at baseline and at reassessment points and 95% confidence intervals will be calculated using a mixed model ANOVA. Post hoc tests will be conducted to identify any significant difference between groups and over time.DiscussionThis pragmatic study will provide evidence for the effectiveness of MMT when compared with a placebo intervention and exercise on headache frequency, intensity, and disability. Limitations are that baseline evaluation of headache parameters may be affected by recall bias. External validity will be limited to the population with a minimum 1-year history of headache. The HADLI is not yet extensively evaluated for its psychometric properties and association between PPT and headache parameters is lacking. Performance bias is inevitable as a single therapist will be delivering all interventions.Trial registrationThe trial was registered prospectively under the Clinical Trial Registry India (Registration number: CTRI/2019/06/019506, dated on 03/06/2019). .

Rural electrification and agricultural family time allocation decisions

ABSTRACT This article investigates the effects of electricity on time allocation in labour market and subsistence activities among adults, adolescents and children living in households in Brazilian rural areas. It explores the eligibility rule of a large-scale public policy programme on access to electricity in rural areas as an instrumental variable. Using the microdata from 2000 to 2010 Demographic Census, it finds that the access to electricity increases the time devoted to subsistence and decreases the time spent in the labour market among all members of agricultural families. These effects are stronger among female individuals. Also, it shows an increase in school attendance among children and male adolescents. There is no schooling effect among female adolescents. Finally, placebo exercises for urban areas suggest that instrumental variable is indeed capturing the effect of the program.

Mutual Fund Bets on Market Power

Taking a firm's competitive position into account benefits investors who are better at evaluating this qualitative information. I find that fund managers who overweight companies with market power outperform their peers. Placebo exercises and an exogenous shock to product market competition around the 9/11 terrorist attacks support this finding. Managers with larger bets on market power are more experienced and long-term oriented. They pursue more illiquid investment strategies, select superior innovators, and more actively avoid competition within their portfolio. My findings show how managers with a superior information production utilize hard-to-process information about industrial organization when picking stocks.

Simultaneus effect of aerobic training and garlic supplementation on resting levels serum of amino transferases in obese men

Background: Obesity is a risk factor for several diseases including metabolic and cardiovascular diseases and is underlying cause of liver diseases. Researches indicate that life style modification via changes in physical activity levels and healthy diet can be beneficial for liver function. The aim of this study was to investigate the effects of aerobic training and garlic supplementation on serum levels of ALT and AST. Methods: In a clinical trial, forty obese men (BMI&gt;30 kg/m2) were randomly assigned into four groups (10 per each) including 1- Exercise+Sepplement (ES) 2- Supplement (S) 3- Exercise+Placebo (EP) and 4- Placebo (P). The subjects received garlic capsule two times per day (each capsule contained 500 mg garlic powder) or placebo (starch) over a period of eight weeks. The subjects in exercise groups performed a supervised progressive aerobic training (3 times a week, %50-%70 HRmax, 20-40 mins) at the same time. Before and after the experimental period body composition analysis was performed and blood samples were taken in a fasting state. Data were analyzed using paired t-test, One-Way ANOVA and Tukey’s post hoc tests at the significance level of P&lt;0.05. Results: The results showed that ALT and AST levels were decreased following 8-week aerobic training (P&lt;0.05). Garlic supplementation also decreased serum levels of aminotransferases (P&lt;0.05). Inter-group differences were seen between exercise groups and placebo (P&lt;0.05). Conclusion: It can be concluded that aerobic training and garlic supplementation can decreases serum aminotransferases levels; however, garlic supplementation has no additional effect on the effects of exercise.

A Randomized Controlled Trial Comparing Physical and Mental Lingual Exercise for Healthy Older Adults.

Mental practice using motor imagery (MP-MI) has been shown to improve motor outcomes of upper and lower extremities especially when combined with physical exercise. Here, we studied community-dwelling, healthy older adults to determine the effects of including an MP-MI component with lingual strengthening exercise. In this pilot study, twenty-nine typically aging participants were assigned to an intervention group: physical lingual exercise (n = 7), physical and MP-MI lingual exercise (n = 8), MPMI lingual exercise (n = 7), or a control group (placebo exercise) (n = 7). All participants completed the assigned exercise regimen with three sessions per day, three days a week, for 6 consecutive weeks. Maximum isometric pressure (MIP) and regular effort saliva swallowing (RESS) pressure were collected at baseline and weeks 2, 4, and 6. A post hoc Bonferroni corrected treatment effect from baseline to week 6 was shown for only participants in the MP-MI/Physical exercise group for MIP (p = 0.003 MPMI/ Physical group; p = 0.11 Control group; p = 0.32 Physical only group; p = 0.14 MP-MI only group) and RESS (p = 0.009 MP-MI/Physical group; p = 0.14 Control group; p = 0.10 Physical only group; p = 0.04 MP-MI only group). Findings also indicate spontaneous carryover of significantly increased swallowing pressure when mental and physical exercise are combined. In conclusion, the potential effect of including an MPMI lingual exercise component in preventative and rehabilitative frameworks with older persons to possibly enhance functional swallowing improvement is promising and should be investigated.

The effect of high doses of ω-3 fatty acid on the structure of the gastrocnemius muscle and on the lipidic profile of Wistar rats submitted to swimming.

Evidence suggests that ω-3 fatty acids (FA) may have an anabolic effect on skeletal muscle. However, questions about dosage, frequency, combined protein supplementation, or different physical exercises remain unanswered. The aim of this study was to quantify by stereology whether supplementation with high dosages of ω-3 FA combined with swimming has an anabolic effect on the skeletal musculature and on the lipid profile of rats. Sixty male Wistar rats were divided into four groups: placebo sedentary (PS), ω-3 FA sedentary (ω-3 S), placebo exercise (PE), and ω-3 FA exercise (ω-3 E). The animals in the PE and ω-3 E groups were submitted to swimming 5 d/wk, with an overload of 15% of body weight. The animals received ω-3 FA or olive oil (placebo) by gavage. After sacrifice, blood samples and the gastrocnemius muscle were collected for analysis. Results from this study did not show a difference in the cross-sectional areas of the gastrocnemius muscle between groups. The administration of high doses of ω-3 FA reduced plasmatic concentrations of low-density lipoprotein. Additionally, an interaction effect was observed between physical exercise and supplementation with ω-3 on levels of high-density lipoprotein. Therefore, the association between these two treatments increased high-density lipoprotein levels. The administration of high doses of ω-3 associated with physical activity may be beneficial in the treatment of dyslipidemia. High doses of ω-3 FA do not cause muscle mass alteration.

Multigenerational Effects of Education Reform: Mother’s Education and Children’s Human Capital in Nepal

Abstract The impact of national efforts to increase supply of education, such as Nepal’s National Education System Plan, may vary across social groups due to differences in social factors that determine access to and demand for education. This paper studies the heterogeneous impact of this reform across gender and caste groups—two important social dimensions in Nepal’s context—over two generations. It uses data from the Nepal National Population and Housing Census 2011 and implements a difference-in-differences framework that utilizes across district variation in intensity of the reform measured by placement of trained teachers per 100 children and across cohort variation in exposure determined by birth year. The study finds that the reform improved females’ education attainment, but such positive effects are not present among women belonging to lower-caste subgroups. In addition, it finds that the reform had positive effects on schooling of the next generation; the multigenerational effects are also concentrated among girls from higher-caste households. The study validates its main findings by conducting a placebo exercise on a sample of individuals who had surpassed their school-going age by the time of the reform.

Does money have a conservative bias? Estimating the causal impact of Citizens United on state legislative preferences

Recent work has suggested that the US Supreme Court’s ruling in Citizens United (2010), eliminating restrictions on independent campaign expenditures, increased the election probabilities of Republican state legislative candidates (Klumpp et al. in J Law Econ 59(1):1–43, 2016). Left unexplored has been whether the Court’s ruling in Citizens United increased not only the number of Republican state legislators, but also the conservatism of their estimated policy preferences, net of any effects on election probabilities. We attempt to distinguish between the possible electoral and preference effects of Citizens United. Our estimates consistently suggest that Citizens United led not only to greater likelihoods of election for Republican state legislative candidates, but also to larger within-district increases in their conservatism. The estimates, which are robust to a series of matching and placebo exercises, may provide support for the claim that more money in elections has contributed to greater conservatism among state-level Republican officeholders.

Shift-Share Designs: Theory and Inference*

Abstract We study inference in shift-share regression designs, such as when a regional outcome is regressed on a weighted average of sectoral shocks, using regional sector shares as weights. We conduct a placebo exercise in which we estimate the effect of a shift-share regressor constructed with randomly generated sectoral shocks on actual labor market outcomes across U.S. commuting zones. Tests based on commonly used standard errors with 5% nominal significance level reject the null of no effect in up to 55% of the placebo samples. We use a stylized economic model to show that this overrejection problem arises because regression residuals are correlated across regions with similar sectoral shares, independent of their geographic location. We derive novel inference methods that are valid under arbitrary cross-regional correlation in the regression residuals. We show using popular applications of shift-share designs that our methods may lead to substantially wider confidence intervals in practice.

Immediate Effect of Semioccluded Vocal Tract Exercises Using Resonance Tube Phonation in Water on Women Without Vocal Complaints

To analyze the immediate effects of semioccluded vocal tract exercises on vocal quality and vocal self-assessment using resonance tube phonation in water in women without voice complaints, and to compare these results with those obtained using tongue trills and unvoiced fricative exercises. This was a quasi-experimental study. The participants were 30 women aged 18-39 years and without vocal complaints. All participants performed three exercises for 3 minutes: experimental exercise (EE: phonation into a resonance flexible tube in water exercise), control exercise (tongue trill exercise), and placebo exercise (PE: unvoiced fricative exercise). Three outcomes were analyzed-vocal self-assessment, auditory-perceptual evaluation, and acoustic analysis. The vocal self-assessment showed significantly greater improvement after EE than after the other exercises. There were no significant differences in auditory-perceptual evaluation or acoustic analyses in any of the voice exercises. The EE promoted an immediate positive effect in the subjective self-assessment, with better results compared with PE. However, the clinical vocal evaluation did not indicate immediate positive effects after 3 minutes of EE, control exercise, or PE.

Dietary Nitrate Supplementation Improves Exercise Tolerance by Reducing Muscle Fatigue and Perceptual Responses.

The present study was designed to provide further insight into the mechanistic basis for the improved exercise tolerance following dietary nitrate supplementation. In a randomized, double-blind, crossover design, twelve recreationally active males completed a dynamic time-to-exhaustion test of the knee extensors after 5 days of consuming both nitrate-rich (NITRATE) and nitrate-depleted beetroot juice (PLACEBO). Participants who improved their time-to-exhaustion following NITRATE performed a time-matched trial corresponding to the PLACEBO exercise duration with another 5 days of dietary nitrate supplementation. This procedure was performed to obtain time-matched exercise trials with (NITRATEtm) and without dietary nitrate supplementation (PLACEBO). Neuromuscular tests were performed before and after each time-matched condition. Muscle fatigue was quantified as percentage change in maximal voluntary torque from pre- to post-exercise (ΔMVT). Changes in voluntary activation (ΔVA) and quadriceps twitch torque (ΔPS100) were used to quantify central and peripheral factors of muscle fatigue, respectively. Muscle oxygen saturation, quadriceps muscle activity as well as perceptual data (i.e., perception of effort and leg muscle pain) were recorded during exercise. Time-to-exhaustion was improved with NITRATE (12:41 ± 07:18 min) compared to PLACEBO (09:03 ± 04:18 min; P = 0.010). NITRATEtm resulted in both lower ΔMVT and ΔPS100 compared to PLACEBO (P = 0.002; P = 0.001, respectively). ΔVA was not different between conditions (P = 0.308). NITRATEtm resulted in reduced perception of effort and leg muscle pain. Our findings extend the mechanistic basis for the improved exercise tolerance by showing that dietary nitrate supplementation (i) attenuated the development of muscle fatigue by reducing the exercise-induced impairments in contractile muscle function; and (ii) lowered the perception of both effort and leg muscle pain during exercise.