Glucocorticoid administration in athletes: Performance, metabolism and detection

It is generally acknowledged in the sporting world that glucocorticoid (GC) use enhances physical performance. This pharmacological class is therefore banned by the World Anti-Doping Agency (WADA) in in-competition samples after systemic but not local (defined as any route other than oral, intravenous, intramuscular or rectal) administration, which thus allows athletes to use GCs for therapeutic purposes. According to the 2016 WADA list, the urine reporting level for all GCs is set at 30ng/ml to distinguish between the authorized and banned routes of administration. The actual data on the ergogenic effects of GC intake are nevertheless fairly recent, with the first study showing improved physical performance with systemic GC administration dating back only to 2007. Moreover, the studies over the last decade coupling ergogenic and metabolic investigations in humans during and after GC intake have shown discrepant results. Similarly, urine discrimination between banned and authorized GC use remains complex, but it seems likely to be improved thanks to new analytical studies and the inclusion of the authorized GC uses (local routes of administration and out-of-competition samples) in the WADA monitoring program. In this review, we first summarize the current knowledge on the ergogenic and metabolic GC effects in humans during various types of exercise. We then present the antidoping legislation and methods of analysis currently used to detect GC abuse and conclude with some practical considerations and perspectives.

Salbutamol intake and substrate oxidation during submaximal exercise

In order to test the hypothesis that salbutamol would change substrate oxidation during submaximal exercise, eight recreationally trained men twice performed 1 h at 60% VO(2) peak after ingestion of placebo or 4 mg of salbutamol. Gas exchange was monitored and blood samples were collected during exercise for GH, ACTH, insulin, and blood glucose and lactate determination. With salbutamol versus placebo, there was no significant difference in total energy expenditure and substrate oxidation, but the substrate oxidation balance was significantly modified after 40 min of exercise. ACTH was significantly decreased with salbutamol during the last 10 min of exercise, whereas no difference was found between the two treatments in the other hormonal and metabolic parameters. The theory that the ergogenic effect of salbutamol results from a change in substrate oxidation has little support during relatively short term endurance exercise, but it is conceivable that longer exercise duration can generate positive findings.

Effects of short-term prednisolone intake during submaximal exercise

PURPOSE

To examine the prednisolone's ergogenic and metabolic effects during submaximal exercise.

METHODS

Ten recreational male athletes completed two cycling trials at 70-75% peak O2 consumption until exhaustion after either placebo (Pla, lactose) or oral prednisolone (Pred, 60 mg.d(-1) for 1 wk) treatment, according to a double-blind and randomized protocol. Blood samples were collected at rest and during exercise and recovery to determine ACTH, growth hormone (GH), prolactin (PRL), DHEA, insulin, blood glucose, and blood lactate values.

RESULTS

Time of cycling was significantly increased after chronic Pred treatment (Pred: 74.5+/-9.5 min; Pla: 46.1+/-3.3 min, P<0.01). Pred intake significantly lowered basal, exercise, and recovery ACTH, DHEA, and PRL concentrations, whereas GH concentrations were significantly lowered by Pred after 30 min of exercise. Blood glucose and insulin were significantly (P<0.05) increased by Pred during the whole experiment and until 30 min of exercise. Blood lactate concentrations were higher after Pred versus Pla at 10 min of exercise until 10 min of recovery (P<0.05).

CONCLUSION

From these data, short-term Pred intake did seem to significantly improve performance during submaximal exercise, with concomitant alterations in hormonal and metabolic responses. Further studies will be necessary to elucidate the mechanisms of these hormonal and metabolic changes, and to determine whether the changes may be associated with the marked performance improvement obtained.

Short-term glucocorticoid intake combined with intense training on performance and hormonal responses

OBJECTIVE

To investigate the effects of short-term prednisolone ingestion combined with intense training on exercise performance, hormonal (adrenocorticotrophic hormone (ACTH), prolactin, luteinising hormone (LH), growth hormone (GH), thyroid-stimulating hormone (TSH), dehydroepiandrosterone (DHEA), testosterone, insulin) and metabolic parameters (blood glucose, lactate, bicarbonate, pH).

METHODS

Eight male recreational athletes completed four cycling trials at 70-75% peak O(2) consumption until exhaustion just before (1) and after (2) either oral placebo or prednisolone (60 mg/day for 1 week) treatment coupled with standardised physical training (2 hours/day), according to a double-blind and randomised protocol. Blood samples were collected at rest, during exercise and passive recovery for the hormonal and metabolic determinations.

RESULTS

Time of cycling was not significantly changed after placebo but significantly increased (p<0.05) after prednisolone administration (50.4 (6.2) min for placebo 1, 64.0 (9.1) min for placebo 2, 56.1 (9.1) min for prednisolone 1 and 107.0 (20.7) min for prednisolone 2). There was no significant difference in any measured parameters after the week of training with placebo but a decrease in ACTH, DHEA, PRL, GH, TSH and testosterone was seen with prednisolone treatment during the experiment (p<0.05). No significant change in basal, exercise or recovery LH, insulin, lactate, pH or bicarbonate was found between the two treatment, but blood glucose was significantly higher under prednisolone (p<0.05) at all time points.

CONCLUSION

Short-term glucocorticoid administration induced a marked improvement in endurance performance. Further studies are needed to determine whether these results obtained in recreational male athletes maintaining a rigorous training schedule are gender-dependent and applicable to elite athletes.

Effects of acute prednisolone intake on substrate utilization during submaximal exercise

We examined the hypothesis that acute therapeutic glucocorticoid intake could change the contribution of fat and carbohydrate (CHO) in energy production during exercise. Nine healthy recreationally-trained male subjects twice performed submaximal exercise (60 min at 60 % VO2max) after ingestion of placebo (Pla) or 20 mg of prednisolone (Pred), according to a double blind and randomized protocol. Respiratory exchange was monitored during exercise and blood samples were collected at rest, every 10 min during exercise and after 5, 10, and 20 min of passive recovery. Pred intake significantly increased total energy expenditure during exercise, but CHO oxidation was lower and fat oxidation higher after Pred vs. Pla. ACTH and IL-6 concentrations were significantly decreased with Pred during exercise, whereas no variations were found in GH, insulin, blood glucose, and lactate between the 2 treatments. In conclusion, it appears that acute prednisolone systemic administration does reduce total carbohydrate oxidation during submaximal exercise. Further studies are necessary to clarify the mechanisms involved and to determine whether this modification in the substrate oxidation balance under glucocorticoid administration in recreationally-trained male subjects could result in a competitive advantage in elite athletes.

Effects of acute prednisolone administration on exercise endurance and metabolism

OBJECTIVE

To examine whether acute glucocorticoid (GC) intake alters performance and selected hormonal and metabolic variables during submaximal exercise.

METHODS

In total, 14 recreational male athletes completed two cycling trials at 70-75% maximum O(2) uptake starting 3 h after an ingestion of either a lactose placebo or oral GC (20 mg of prednisolone) and continuing until exhaustion, according to a double-blind randomised protocol. Blood samples were collected at rest, after 10, 20, 30 minutes, and at exhaustion and recovery for measurement of growth hormone (GH), adrenocorticotropic hormone (ACTH), dehydroepiandrosterone (DHEA), prolactin, insulin, blood glucose, lactate and interleukin (IL)-6 determination.

RESULTS

Cycling duration was not significantly changed after GC or placebo administration (55.9 (5.2) v 48.8 (2.9) minutes, respectively). A decrease in ACTH and DHEA (p<0.01) was observed with GC during all of the experiments and in IL-6 after exhaustion (p<0.05). No change in basal, exercise or recovery GH, prolactin, insulin or lactate was found between the two treatments but blood glucose was significantly higher with GC (p<0.05) at any time point.

CONCLUSION

From these data, acute systemic GC administration does seem to alter some metabolic markers but did not influence performance during submaximal exercise.

Effects of acute salbutamol intake during supramaximal exercise in women

OBJECTIVE

To study the effects of an acute therapeutic oral intake of beta(2) agonist on performance and substrate response during supramaximal exercise in women.

METHODS

12 healthy moderately trained female volunteers performed a Wingate test after ingestion of placebo (Pla) and salbutamol (Sal; 4 mg) according to a double-blind randomised crossover study. Blood samples were collected at rest, at the end of exercise and after 5 (r5), 10 (r10) and 15 (r15) min of passive recovery for adrenocorticotropic hormone (ACTH), growth hormone (GH), insulin, blood glucose and lactate measurements.

RESULTS

Peak power (PP) and mean power (MP) significantly increased whereas time to peak power was significantly shorter with Sal than with Pla (p<0.05). No change was observed in the fatigue index. ACTH was not significantly modified but r15 growth hormone significantly decreased (p<0.05) after the intake of Sal. Both blood INS and blood glucose were significantly increased by the intake of Sal during all the experiments (p<0.01). Blood lactate was significantly increased by the intake of Sal compared with that of Pla (p<0.05) after 10 and 15 min of passive recovery.

CONCLUSION

From these data, acute therapeutic oral intake of Sal seems to induce, irrespective of the subjects' gender, an improvement in performance during a supramaximal exercise--that is, increase in PP and MP. Further studies are necessary to clarify whether the mechanisms involved in the response to intake of Sal are linked to central and/or peripheral pathways.

Effects of acute prednisolone intake during intense submaximal exercise

To study the effects of a therapeutical dose of corticosteroid alone or associated with beta-2 agonist on performance and substrate response during intense submaximal exercise, seven healthy moderately trained male volunteers participated in the double-blind randomized cross-over study. An intense endurance exercise test to exhaustion was performed after ingestion of placebo (Pla), 20 mg prednisolone (Pred), and 20 mg prednisolone plus 4 mg salbutamol (Pred-Sal). Blood samples were collected at rest, after 5, 10 min of exercise, at exhaustion, and after 5 (r5), 10 (r10), and 20 (r20) min of passive recovery for ACTH, growth hormone, insulin, blood glucose, and lactate measurements. There were no significant differences in exercise time to exhaustion between the three treatments (Pla: 21.5 +/- 2.9; Pred: 22.0 +/- 2.5; Pred-Sal: 24.2 +/- 2.8 min). ACTH was significantly lowered after Pred and Pred-Sal vs. Pla from the start of exercise to the end of the experiment (p < 0.05). Pred and Pred-Sal increased resting and recovery (r10 and r20) significantly but not exercise blood glucose values. There were no significant differences in growth hormone concentrations between the three treatments whereas insulin was significantly higher at rest, during exercise, and at r20 after Pred-Sal administration vs. Pred and Pla (p < 0.05). Pred and Pred-Sal showed no significant effect on blood lactate compared with Pla treatment. These preliminary results do not support the hypothesis that acute oral therapeutic corticosteroid intake alone or associated with beta-2 mimetic improves performance during intense submaximal exercise, but further studies are necessary with tests of longer duration.

Short term salbutamol ingestion and supramaximal exercise in healthy women

OBJECTIVE

To test the hypothesis that chronic salbutamol intake improves performance during supramaximal exercise and to estimate the effects of this treatment on body composition, bone mass, and metabolic indices in healthy women.

METHODS

Fourteen female volunteers (seven sedentary and seven recreationally trained) performed a 30 second Wingate test with and without salbutamol ingestion (12 mg/day for four weeks) in a random, double blind, crossover design. Blood samples were collected at rest, at the end of the test, and during passive recovery for lactate measurement. Body composition and bone mass were determined by dual energy x ray absorptiometry.

RESULTS

Peak power appeared significantly earlier and was significantly (p<0.05) increased after salbutamol intake in all subjects. There was no difference in total work performed and fatigue indices with salbutamol compared with placebo. No significant alterations in lean or fat body mass and bone variables were observed with salbutamol treatment in either trained or untrained subjects during the trial. In contrast, blood lactate was significantly (p<0.05) increased during the recovery period after salbutamol ingestion compared with placebo.

CONCLUSION

As in men, chronic administration of therapeutic concentrations of salbutamol did not induce an anabolic effect in women but increased maximal anaerobic power. Further studies are necessary to clarify the mechanisms involved.

Alteration of trabecular bone under chronic beta2 agonists treatment

PURPOSE

beta2 adrenergic agonists are widely used as doping agents. Their side effects on bone, especially microarchitecture, remain unknown. The purpose of this study was to evaluate the effects of chronic clenbuterol and salbutamol treatment on bones of growing rats.

METHODS

Twelve-week-old Wistar female rats were divided into three groups: salbutamol (4 mg.kg(-1).d(-1)), clenbuterol (2 mg.kg(-1).d(-1)), and normal saline (0.5 mL.kg(-1).d(-1)) and treated for 6 wk. Proximal tibia and lumbar spine L4 were analyzed by absorptiometry and by 3D microcomputed tomography. Bending and compression tests were used to measure their mechanical properties.

RESULTS

After 6 wk, the salbutamol and clenbuterol groups had lower bone mineral density (BMD) in the tibia, proximal tibia, and vertebrae. Trabecular number and bone volume for the vertebrae were lower in animals treated with clenbuterol (Tb.N: -14.31%, P < 0.001; BV/TV: -21.07%, P < 0.001) or salbutamol (TbN: -12.7%, P < 0.001; BV/TV: -19.7%, P < 0.001) than in controls. Mechanical properties of the tibia were affected by clenbuterol with a lower ultimate force (P = 0.02) and a trend in lower energy to ultimate force (P = 0.053). In vertebrae, salbutamol and clenbuterol induced lower ultimate force. Clenbuterol significantly increased muscle mass (+58.83%, P < 0.01) and reduced fat mass (-28.75%, P < 0.01) compared with controls +17.07 and -7.34%, respectively.

CONCLUSION

This study shows a negative effect of clenbuterol and salbutamol on the mechanical properties and microarchitecture of trabecular bone. In the clenbuterol group it was notable that the bone loss contrasts with the anabolic effect on muscle mass. Clearly an increase of muscle mass with enhanced bone fragility augments the risk of fractures for humans or animals treated with beta2 agonists as part of a doping regimen.

The mode of bone conservation does not affect the architecture and the tensile properties of rat femurs

The bone samples used in clinical and experimental trials must be the less damaged as possible to avoid alterations of their properties. However, the mode of storage might possibly alter the bone properties, particularly microarchitecture and strength. The aim of our study was to analyze the effects of deep-freezing and alcohol conservation techniques on the densitometric, microarchitectural and biomechanical parameters of rat femurs. The left femurs were elongated in uniaxial tension up to breakdown in order to calculate biomechanical parameters. The densitometric and microarchitectural properties of right femurs were evaluated using dual-energy X-ray absorptiometry and microcomputed tomography, respectively. Results showed no significant difference in the parameters investigated between deep-freezing, alcohol storage and fresh femurs when comparing each parameter separately. Therefore, one month storage in alcohol or deep-freezing seemed to induce no harmful effect on densitometric, microarchitectural and biomechanical parameters of rat femurs.

Severe bone alterations under beta2 agonist treatments: bone mass, microarchitecture and strength analyses in female rats

AIMS

Beta2 adrenergic agonists are widely used in therapeutics and as doping agents by athletes. However, their effects on bone tissue, especially bone microarchitecture, remain poorly understood. Using three-dimensional (3D) microtomography, dual-energy X-ray absorptiometry, biomechanical testing and enzyme-linked immunosorbent assay, we evaluated the effects of two beta2 agonists, clenbuterol and salbutamol, on bone in growing rats.

METHODS

Twelve-week-old Wistar female rats (N = 39), divided in 3 groups, received during 6 weeks either salbutamol (4 mg/kg/day), clenbuterol (2 mg/kg/day) or normal saline (0.5 ml/kg/day) by subcutaneous injections.

RESULTS

After 6 weeks, the salbutamol and clenbuterol groups displayed lower bone mineral content (BMC), femoral length and cortical width than controls. Clenbuterol treatment further reduced bone mineral density. Bone microarchitecture was clearly altered by clenbuterol, as evidenced by lower trabecular number (-40.40%; P < 0.001), connectivity and trabecular bone volume (-42.85%; P < 0.001), leading to lower ultimate force. Clenbuterol significantly increased muscle mass (P < 0.01) and reduced fat mass when compared to controls. Salbutamol did not seem to have any effect on bone microarchitecture or body composition. Both beta2 agonists increased the bone resorption marker (C-terminal collagen crosslinks) without any change of a bone formation marker. At the end of the treatment, a drop in leptin was seen in the clenbuterol group only. Leptin levels were correlated with BMC (r = 0.69, P = 0.003).

CONCLUSION

These results confirm the deleterious effect of beta2 agonists on bone mass and show the negative effects of clenbuterol on trabecular bone microarchitecture. Bone loss occurred independently from muscle mass but was related to fat mass. A leptin-mediated effect on bone tissue seems likely. These pathophysiological effects may have important consequences in human therapeutics and doping.

Effects of Long-Term Tennis Playing on the Muscle-Bone Relationship in the Dominant and Nondominant Forearms

The relationship between muscle strength and bone mineral density illustrates the positive effect of mechanical loading on bone. But local and systemic factors may affect both muscle and bone tissues. This study investigated the effects of long-term tennis playing on the relationship between lean tissue mass and bone mineral content in the forearms, taking the body dimensions into account. Fifty-two tennis players (age 24.2 ± 5.8 yrs, 16.2 ± 6.1 yrs of practice) were recruited. Lean tissue mass (LTM), bone area, bone mineral content (BMC), and bone mineral density were measured at the forearms from a DXA whole-body scan. Grip strength was assessed with a dynamometer. A marked side-to-side difference (p <  0.0001) was found in favor of the dominant forearm in all parameters. Bone area and BMC correlated with grip strength on both sides (r = 0.81-0.84, p <  0.0001). The correlations were still significant after adjusting for whole-body BMC, body height, or forearm length. This result reinforced the putative role of the muscles in the mechanical loading on bones. In addition, forearm BMC adjusted to LTM or grip strength was higher on the dominant side, suggesting that tennis playing exerts a direct effect on bone. Key words: bone mineral content, muscle strength, unilateral loading, mechanical stress, absorptiometry