Beta-Adrenergic Stimulation Induces Resistance Training-Like Adaptations in Human Skeletal Muscle: Potential Role of KLHL41.

Skeletal muscle mass plays a pivotal role in metabolic function, but conditions such as bed rest or injury often render resistance training impractical. The beta-adrenergic receptor has been highlighted as a potential target to promote muscle hypertrophy and treat atrophic conditions. Here, we investigate the proteomic changes associated with beta-adrenergic-mediated muscle hypertrophy, using resistance training as a hypertrophic comparator.

Active ischemic pre-conditioning does not additively improve short-term high-intensity cycling performance when combined with caffeine ingestion in trained young men.

We investigated the effect of ischemic preconditioning (IPC) with and without caffeine supplementation on mean power output (MPO) during a 4-min cycling time-trial (TT). In a double-blinded, randomized, crossover-design, 11 trained men performed a TT on 4 days separated by ∼1 week. One hour before TT, participants ingested either caffeine (3 mg kg bw) or placebo pills, after which femoral blood-flow was either restricted with occlusion cuffs inflated to ∼180 mmHg (IPC), or sham-restricted (0-10 mmHg; Sham) during 3 × 2-min low-intensity cycling (10% of incremental peak power output).

Low-Volume Speed Endurance Training with Reduced Volume Improves Short-Term Exercise Performance in Highly Trained Cyclists.

Purpose: We investigated the effects of low- and high-volume speed endurance training (SET), with a reduced training volume, on sprint ability, short- and long-term exercise capacity, muscle mitochondrial properties, ion transport proteins, and maximal enzyme activity in highly trained athletes.

Methods: Highly trained male cyclists (maximal oxygen consumption (V̇O 2max ): 68.3 ± 5.

No additive effect of creatine, caffeine, and sodium bicarbonate on intense exercise performance in endurance-trained individuals.

Background: Athletes commonly use creatine, caffeine, and sodium bicarbonate for performance enhancement. While their isolated effects are well-described, less is known about their potential additive effects.

Methods: Following a baseline trial, we randomized 12 endurance-trained males (age: 25 ± 5 years, VO: 56.

Beyond bronchodilation: Illuminating the performance benefits of inhaled beta -agonists in sports.

Given the prevalent use of inhaled beta -agonists in sports, there is an ongoing debate as to whether they enhance athletic performance. Over the last decades, inhaled beta -agonists have been claimed not to enhance performance with little consideration of dose or exercise modality. In contrast, orally administered beta -agonists are perceived as being performance enhancing, predominantly on muscle strength and sprint ability, but can also induce muscle hypertrophy and slow-to-fast fiber phenotypic switching.

Inhaled salbutamol induces leanness in well-trained healthy females but not males during a period of endurance training: a randomised controlled trial.

Introduction: Many athletes use short-acting inhaled β-agonists multiple times weekly during training sessions to prevent exercise-induced bronchoconstriction, but it is unclear if treatment impairs training outcomes. Herein, we investigated performance adaptations in well-trained females and males training with prior inhalation of salbutamol.

Methods: 19 females and 21 males with maximal oxygen uptake (') of 50.

Inhaled beta -agonist, formoterol, enhances intense exercise performance, and sprint ability in elite cyclists.

Purpose: Many athletes use long-acting beta -agonist formoterol in treatment of asthma. However, studies in non-athlete cohorts demonstrate that inhaled formoterol can enhance sprint performance calling into question whether its use in competitive sports should be restricted. We investigated whether formoterol at upper recommended inhaled doses (54 μg) would enhance sprint ability and intense exercise performance in elite cyclists.

Decline in Iran's groundwater recharge.

Groundwater recharge feeds aquifers supplying fresh-water to a population over 80 million in Iran-a global hotspot for groundwater depletion. Using an extended database comprising abstractions from over one million groundwater wells, springs, and qanats, from 2002 to 2017, here we show a significant decline of around -3.8 mm/yr in the nationwide groundwater recharge.

Inhaled formoterol impairs aerobic exercise capacity in endurance-trained individuals: a randomised controlled trial.

Background: The 2022 Global Initiative for Asthma guidelines emphasise the inhaled long-acting β-agonist formoterol as part of the first treatment step, and therefore formoterol use among athletes will probably increase. However, prolonged supratherapeutic use of inhaled β-agonists impairs training outcomes in moderately trained men. We investigated whether inhaled formoterol, at therapeutic doses, imposes detrimental effects in endurance-trained individuals of both sexes.

Asthma and exercise-induced bronchoconstriction in athletes: Diagnosis, treatment, and anti-doping challenges.

Athletes often experience lower airway dysfunction, such as asthma and exercise-induced bronchoconstriction (EIB), which affects more than half the athletes in some sports, not least in endurance sports. Symptoms include coughing, wheezing, and breathlessness, alongside airway narrowing, hyperresponsiveness, and inflammation. Early diagnosis and management are essential.

Urine concentrations of vilanterol and its metabolites, GSK932009 and GW630200, after inhalation of therapeutic and supratherapeutic doses.

The 2023 Prohibited List issued by the World Anti-Doping Agency (WADA) permits athletes to inhale the beta -agonist vilanterol at a standard dose of 25 μg daily. However, given limited data on urine pharmacokinetics, vilanterol has no urinary threshold or decision limit to discriminate therapeutic from supratherapeutic use. We investigated urine concentrations of vilanterol and its main metabolites GSK932009 and GW630200 over 0-72 h following inhalation of therapeutic (25 μg) or supratherapeutic (100 μg) doses and repeat-dose administration for 7 days of 25 or 100 μg·day in 25 trained men and women.

Myonuclear addition is associated with sex-specific fiber hypertrophy and occurs in relation to fiber perimeter not cross-sectional area.

It is unclear whether resistance training-induced myofiber hypertrophy is affected by sex, and whether myonuclear addition occurs in relation to the myonuclear domain and can contribute to explaining a potential sex-specific hypertrophic response. This study investigated the effect of 8 wk of resistance training on myofiber hypertrophy and myonuclear addition in 12 males (28 ± 7 yr; mean ± SD) and 12 females (27 ± 7 yr). Muscle biopsies were collected from m.

Analysis of oxygen isotopes of inorganic phosphate (δO) in freshwater: A detailed method description for obtaining oxygen isotopes of inorganic phosphate in environmental water samples.

The ability to identify the origin of phosphorus and understand processes controlling P cycling is essential for designing effective mitigation and restoration of eutrophic freshwater ecosystems. The oxygen isotope composition of orthophosphate (δO) has significant potential as a tracer for P entering freshwater ecosystems. However, methods of analysis of δO are still in their preliminary stages and have proven challenging to implement for new practitioners.

Effects of Follicular and Luteal Phase-Based Menstrual Cycle Resistance Training on Muscle Strength and Mass.

There is an increasing interest in female athletic performance-especially concerning the impact of the female menstrual cycle on training response. Indeed, fluctuations in female sex hormones, estrogen and progesterone, during the menstrual cycle regulate protein metabolism and recovery processes in skeletal muscle and may thus impact exercise training-related outcomes. Studies demonstrate that anaerobic capacity and muscle strength are greatest during the follicular phase of the menstrual cycle, when estrogen levels peak.

Beta -agonist increases skeletal muscle interleukin 6 production and release in response to resistance exercise in men.

Objective: Several tissues produce and release interleukin-6 (IL-6) in response to beta -adrenergic stimulation with selective agonists (beta -agonists). Moreover, exercise stimulates muscle IL-6 production, but whether beta -agonists regulate skeletal muscle production and release of IL-6 in humans in association with exercise remains to be clarified. Thus, we investigated leg IL-6 release in response to beta -agonist salbutamol in lean young men at rest and in recovery from resistance exercise.

Active Relative to Passive Ischemic Preconditioning Enhances Intense Endurance Performance in Well-Trained Men.

Purpose: This study tested the hypothesis of whether ischemic exercise preconditioning (IPC-Ex) elicits a better intense endurance exercise performance than traditional ischemic preconditioning at rest (IPC-rest) and a SHAM procedure.

Methods: Twelve men (average V˙O2max ∼61 mL·kg-1·min-1) performed 3 trials on separate days, each consisting of either IPC-Ex (3 × 2-min cycling at ∼40 W with a bilateral-leg cuff pressure of ∼180 mm Hg), IPC-rest (4 × 5-min supine rest at 220 mm Hg), or SHAM (4 × 5-min supine rest at <10 mm Hg) followed by a standardized warm-up and a 4-minute maximal cycling performance test. Power output, blood lactate, potassium, pH, rating of perceived exertion, oxygen uptake, and gross efficiency were assessed.

Muscle hypertrophic effect of inhaled beta -agonist is associated with augmented insulin-stimulated whole-body glucose disposal in young men.

Rodent studies highlight enhancement of glucose tolerance and insulin sensitivity as potential clinically relevant effects of chronic beta -agonist treatment. However, the doses administered to rodents are not comparable with the therapeutic doses used for humans. Thus, we investigated the physiological effects of prolonged beta -agonist treatment at inhaled doses resembling those used in respiratory diseases on insulin-stimulated whole-body glucose disposal and putative mechanisms in skeletal muscle and adipose tissue of healthy men.

No additive effect of acetaminophen when co-ingested with caffeine on cycling performance in well-trained young men.

We investigated the effect of caffeine and acetaminophen on power output during a 6-min performance test, peripheral fatigue, and muscle protein kinase A (PKA) substrate phosphorylation. Fourteen men [age (means ± SD): 26 ± 6 yr; V̇o: 63.9 ± 5.

An Abductive Inference Approach to Assess the Performance-Enhancing Effects of Drugs Included on the World Anti-Doping Agency Prohibited List.

Some have questioned the evidence for performance-enhancing effects of several substances included on the World Anti-Doping Agency's Prohibited List due to the divergent or inconclusive findings in randomized controlled trials (RCTs). However, inductive statistical inference based on RCTs-only may result in biased conclusions because of the scarcity of studies, inter-study heterogeneity, too few outcome events, or insufficient power. An abductive inference approach, where the body of evidence is evaluated beyond considerations of statistical significance, may serve as a tool to assess the plausibility of performance-enhancing effects of substances by also considering observations and facts not solely obtained from RCTs.

β-Adrenergic agonist salbutamol augments hypertrophy in MHCIIa fibers and sprint mean power output but not muscle force during 11 weeks of resistance training in young men.

In this study, we examined the effect of β-agonist salbutamol at oral doses during a period of resistance training on sprint performance, quadriceps contractile function, skeletal muscle hypertrophy, fiber type composition, maximal activity of enzymes of importance for anaerobic energy turnover, and sarcoplasmic reticulum Ca handling in young men. Twenty-six men (23 ± 2 yr; means ± SD) were randomized to daily intake of oral salbutamol (16 mg/day; RES+SAL) or placebo (RES) during 11 wk of full-body resistance training 3 times/wk. Mean power output during 10-s maximal cycling increased more ( = 0.

Pharmacokinetics of salmeterol and its main metabolite α-hydroxysalmeterol after acute and chronic dry powder inhalation in exercising endurance-trained men: Implications for doping control.

As of 2020, use of beta -agonist salmeterol is restricted by the World Anti-Doping Agency (WADA) and is only permitted by inhalation at therapeutic doses not exceeding 200 μg in 24 h. In contrast to beta -agonists salbutamol and formoterol, WADA has not established a urine threshold for salmeterol despite its muscle hypertrophic actions observed in animals. Herein, we investigated plasma (0-4 h) and urine (0-24 h) concentrations (by ultra-high-performance liquid chromatography-tandem mass spectrometry [UHPLC-MS/MS]) of salmeterol and α-hydroxysalmeterol after dry powder inhalation at supratherapeutic (400 μg) and high therapeutic (200 μg) doses, and after seven consecutive days of therapeutic inhalation (200 μg × day ) in 11 healthy endurance-trained men.

Single-dose administration of clenbuterol is detectable in dried blood spots.

Clenbuterol is a β -agonist prescribed for asthmatic patients in some countries. Based on its anabolic and lipolytic effects observed in studies on rodents and in livestock destined for food production, clenbuterol is abused by bodybuilders and athletes seeking leanness. Urinary clenbuterol analysis is part of routine doping analysis.

Anabolic and lipolytic actions of beta -agonists in humans and antidoping challenges.

Inhaled beta -adrenoceptor agonists (beta -agonists) are among the most used substances in competitive sports. The 2020 Prohibited List issued by the World Anti-Doping Agency restricts use of all selective and non-selective beta -agonists in- and out- of competition with few exemptions. Formoterol, salbutamol, and salmeterol are allowed by inhalation within defined dosing limits.