Pharmacogenetic Effects of Inhaled Salbutamol on 10-km Time Trial Performance in Competitive Male and Female Cyclists

Beta2-agonist Impairs Muscle Insulin Sensitivity in Persons With Insulin Resistance

CONTEXT

Given the promising effects of prolonged treatment with beta2-agonist on insulin sensitivity in animals and nondiabetic individuals, the beta2-adrenergic receptor has been proposed as a target to counter peripheral insulin resistance. On the other hand, rodent studies also reveal that beta2-agonists acutely impair insulin action, posing a potential caveat for their use in treating insulin resistance.

OBJECTIVE

To assess the impact of beta2-agonist on muscle insulin action and glucose metabolism and identify the underlying mechanism(s) in 10 insulin-resistant subjects.

METHODS AND PARTICIPANTS

In a crossover design, we assessed the effect of beta2-agonist on insulin-stimulated muscle glucose uptake during a 3-hour hyperinsulinemic isoglycemic clamp with and without intralipid infusion in 10 insulin-resistant, overweight subjects. Two hours into the clamp, we infused beta2-agonist. We collected muscle biopsies before, 2 hours into, and by the end of the clamp and analyzed them using metabolomic and lipidomic techniques.

RESULTS

We establish that beta2-agonist, independently from and additively to intralipid, impairs insulin-stimulated muscle glucose uptake via different mechanisms. In combination, beta2-agonist and intralipid nearly eliminates insulin-dependent muscle glucose uptake. Although both beta2-agonist and intralipid elevated muscle glucose-6-phosphate, only intralipid caused accumulation of downstream muscle glycolytic intermediates, whereas beta2-agonist attenuated incorporation of glucose into glycogen.

CONCLUSION

Our findings suggest that beta2-agonist inhibits glycogenesis, whereas intralipid inhibits glycolysis in skeletal muscle of insulin-resistant individuals. These results should be addressed in future treatment of insulin resistance with beta2-agonist.

Prevalence of Prohibited Substance Use and Methods by Female Athletes: Evidence of Gender-Related Differences

To achieve optimal sports performances, women and men may show specific doping practices because of the physiological and psychological gender differences, but there are few data on this topic. Here, we report the apparent use of prohibited substances and methods by female athletes based on analyses of the doping tests collected by the French Anti-Doping Agency from 2013 to 2019. We compared the frequency of use and the ergogenic and side effects to those of their male counterparts. The results revealed lower use of prohibited substances in female vs. male athletes, with significantly fewer anabolic agents, hormone and metabolic modulators, and cannabinoids. Gender specificity in utilization of substance classes was also shown. Relatively lower use of hormone modulators and cannabinoids and higher use of beta-2 agonists, diuretics and glucocorticoids were found in the woman cohort compared with men cohort, combined with the different choice of substances, possibly because of the altered ergogenic and/or side effects. However, no impact due to gender regarding the sports disciplines was observed, with both women and men showing similar use of anabolic agents, mainly in the anaerobic sports, and EPO and corticoids, mainly in endurance or mixed sports. Further studies are needed to put these French data into a global perspective, comparing uses across countries and exploring possible new developments in the fight against doping in women.

Inconsistent calculation methodology for the eucapnic voluntary hyperpnoea test affects the diagnosis of exercise-induced bronchoconstriction

Introduction

The eucapnic voluntary hyperpnoea (EVH) challenge is used to screen for exercise-induced bronchoconstriction. Several criteria have been proposed to determine the decrease in lung function (fall index, FI) following EVH. We compared three published FI calculation methods to determine if they affect the diagnostic classification.

Methods

The three FIs were calculated for 126 EVH tests. Spirometry was performed in duplicate at baseline and repeated 3, 5, 10, 15 and 20 min following 6 min of EVH. The higher of the two forced expiratory volume in 1 s (FEV₁) measures at all time-points post-hyperpnoea was selected for the calculation of the FIs. The FI_A was determined as the single lowest of the five postchallenge values, and a test was considered positive if FEV₁ decreased ≥10 %. In FI_B, a test was considered positive if FEV₁ decreased ≥10% at two consecutive post-challenge time-points. The FI_C was calculated identically to FI_A, but was normalised to the achieved minute ventilation during the EVH challenge.

Results

Calculation method affected the raw FIs with FI_B generating the smallest and FI_C generating the highest values (p<0.001) and a within-subject range of 7%±10%. The number of positive tests differed between the calculation criteria: FI_A: 62, FI_B: 48 and FI_C: 70, p<0.001. Nineteen participants (15%) tested positive in one or two FI methods only, indicating that the FI method used determined whether the test was positive or negative.

Discussion

Inconsistency in methodology of calculating the FI leads to differences in the diagnostic rate of the EVH test, with potential implications in both treatment and research outcomes.