K. Collomp

The effect of shuttle test protocol and the resulting lactacidaemia on maximal velocity and maximal oxygen uptake during the shuttle exercise test

SummaryThe purpose of this study was to investigate the influence of the shuttle test protocol (20-MST) and the resulting lactacidaemia on maximal velocity (Vmax) and maximal oxygen uptake (VO2max). Firstly, three randomly assigned tests to exhaustion were performed by 12 subjects: the treadmill test, the 20-MST, and a continuous running track test using the same prerecorded 1-min protocol as in the 20-MST (T1). One week later, subjects performed another track test, which was conducted up to the same level of effort as attained during the 20-MST (T2). For each test, Vmax, VO2max) lactate concentration at rest and during recovery, maximal heart rate, and distance covered were determined. The results indicated that the 20-MST underestimated Vmax; only Tl satisfactorily assessed Vmax (F=15.49, P<0.001). At the same level of effort, the peak blood lactate concentration (t=2.7, P<0.02) and VO2max (t=11.35, P<0.001) values were higher for the shuttle than for the continuous protocol. It was concluded that Vmax was limited by the running backwards and forwards in the protocol of the shuttle test. The higher values of peak blood lactate concentration and its earlier appearance obtained for the shuttle may have been one of the limiting factors of Vmax. However, the higher values of VO2max obtained for the 20-MST were most likely due to a combination of the relative hyperlactacidaemia and the biomechanical complexities required for this type of protocol.

Effects of acute salbutamol intake during supramaximal exercise in women.

Objective: To study the effects of an acute therapeutic oral intake of β2 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.

The diurnal patterns of cortisol and dehydroepiandrosterone in relation to intense aerobic exercise in recreationally trained soccer players

Diurnal patterns of cortisol and dehydroepiandrosterone (DHEA) secretion, the two main peripheral secretory products of the hypothalamic–pituitary–adrenal neuroendocrine stress axis, have been well characterized in rest conditions but not in relation to physical exercise. The purpose of this investigation was therefore to determine the effects of an intense 90-min aerobic exercise on the waking diurnal cortisol and DHEA cycles on three separate days [without exercise, with morning exercise (10:00–11:30 h), and with afternoon exercise (14:00–15:30 h)] in nine recreationally trained soccer players. Saliva samples were collected at awakening, 30 min after awakening, and then every 2 h from 08:00 to 22:00 h. A burst of secretory activity was found for cortisol (p < 0.01) but not for DHEA after awakening. Overall, diurnal decline for both adrenal steroids was observed on resting and exercise days under all conditions. However, there was a significant increase in salivary cortisol concentrations on the morning-exercise and afternoon-exercise days at, respectively, 12:00 h (p < 0.05) and 16:00 h (p < 0.01), versus the other trials. This acute response to exercise was not evident for DHEA. The results of this investigation indicate that 90 min of intense aerobic exercise does not affect the circadian pattern of salivary adrenal steroids in recreationally trained athletes over a 16-h waking period, despite a transitory increase in post-exercise cortisol concentration. Further studies are necessary to determine whether these results are applicable to elite athletes or patients with cortisol or DHEA deficiency.

Cortisol, DHEA, and testosterone concentrations in saliva in response to an international powerlifting competition

The purpose of this study was to examine salivary cortisol, dehydroepiandrosterone (DHEA), and testosterone responses to the bench press in an international powerlifting competition and to determine whether these salivary hormone concentrations could be used to predict performance. Twenty-six elite athletes (13 females and 13 males) provided saliva samples during the official weighing-in and after the last attempt at the bench press, as well as at baseline on a non-competition day. Performance index was determined with the Wilks formula, which adjusts powerlifting scores according to body mass. Salivary cortisol concentrations were significantly increased in all subjects after the bench press (p < 0.01), whereas DHEA concentrations were significantly increased in women (p < 0.01) but not in men after the bench press. No significant change in testosterone concentrations was observed during the experiment in either men or women, which resulted in a marked decrease in the testosterone/cortisol ratio. The performance index showed no significant correlation with any of the hormone responses to competition. In conclusion, despite the increase in stress adrenocortical hormone responses to an international powerlifting competition, these hormone concentrations alone are not predictors of bench press performance in elite powerlifting athletes.

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 O2 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.

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.

Changes in steroid hormones during an international powerlifting competition.

The purpose of this study was to assess changes in the steroid hormone levels of elite athletes during an international powerlifting competition. Baseline cortisol, DHEA and testosterone were determined in saliva samples in 19 (8 men, 11 women) junior and sub-junior athletes on the day before competition, and then on the competition day during the official weighing and in the hour after competition. Performance was determined by total output and the Wilks formula. No change in saliva steroid concentrations was observed between samples collected on the day before competition and the weighing samples. There was no gender effect on cortisol concentrations but saliva testosterone levels were always significantly higher in men than in women (p<0.01), as was end-competition DHEA (p<0.05). Cortisol and DHEA were significantly increased in male and female athletes after the competition (respectively, p<0.01 and p<0.05), whereas end-competition testosterone concentrations were only significantly increased in men (p<0.01). Significant relationships were demonstrated between performance and end-competition cortisol levels in women and end-competition testosterone levels in men. These data indicate that workouts during an international powerlifting competition produce a significant increase in adrenal steroid hormones in both genders, with an increase in male gonadal steroid hormone. Further studies are necessary to examine the changes in oestradiol and progesterone in women and their potential impact on performance during international powerlifting competition.

DHEA, physical exercise and doping.

The dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEA-S) concentrations during acute and chronic exercise (training) have been investigated only fairly recently. DHEA is generally preferred to DHEA-S for exploring the acute exercise repercussions in laboratory or field tests because of its shorter elimination half-life. Conversely, DHEA-S is preferred to estimate chronic adaptations. Both can be measured noninvasively in saliva, and it is therefore possible to follow these hormone responses in elite athletes during competitive events and in healthy and pathological populations, without imposing additional stress. Indeed, the correlation between saliva and serum concentrations is high for steroid hormones, both at rest and during exercise. In this review, we will first summarize the current knowledge on the DHEA/DHEA-S responses to exercise and examine the potential modulating factors: exercise intensity, gender, age, and training. We will then discuss the ergogenic effects that athletes expect from the exogenous administration of DHEA and the antidoping methods of analysis currently used to detect this abuse.

Serum and Saliva Adrenocortical Hormones in Obese Diabetic Men During Submaximal Exercise

The aim of this study was to evaluate serum and saliva adrenocortical hormones and their relationships at rest and during submaximal exercise and recovery in 9 obese diabetic middle-aged men (BMI: 35.2 ± 1.6 kg/m (2)). Blood and saliva samples were taken at rest, every 10 min of a 30-min cycling exercise at 70% of maximal heart rate, and after 10 min of recovery in order to analyze cortisol, dehydroepiandrosterone sulfate (DHEA-S) and dehydroepiandrosterone (DHEA). Serum and saliva cortisol increased significantly during recovery (p<0.05), but no significant difference was observed between the rest, exercise, and recovery DHEA-S and DHEA concentrations. A strong correlation was found at rest between both serum and saliva cortisol (r=0.72, p<0.001) and DHEA-S and DHEA (r=0.93, p<0.001). Serum DHEA-S and saliva DHEA remained strongly correlated during and after the submaximal exercise (r=0.81, p<0.001), whereas a weaker but still significant relationship was observed between serum and saliva cortisol during and after the exercise (r=0.52, p<0.001). In conclusion, these results suggest that saliva adrenocortical hormones, and especially saliva DHEA, may offer a practical surrogate for serum concentrations during both rest and exercise in obese diabetic men.

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 O2 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.