Adrenal medulla responsiveness to the sympathetic nervous activity in sprinters and untrained subjects during a supramaximal exercise.
The purpose of this study was to compare the adrenal medullar responsiveness to the sympathetic nervous activity between sprinters and untrained subjects after a supramaximal exercise (Wingate-test). Thirteen subjects took part in this study: 7 male athletes (20.3+/-1.8 years) competing in sprint running (S) and 6 untrained men (UT) (21+/-1.3 years). They performed an incremental treadmill test to determine the maximal oxygen uptake (VO2max), a force-velocity test and a Wingate-test on 3 different days, separated by a maximal interval of 15 days. The maximal power (Wmax) and the mean power (W) were determined from the Wingate-test on a cycle ergometer. Plasma lactate, adrenaline and noradrenaline concentrations were determined at rest (La0, A0, NA0), immediately after the Wingate-test (Amax, NAmax) and after 5 minutes recovery (Lamax, A5 and NA5). S exhibited higher performances than UT during the Wingate-test as shown by their significantly higher values of Wmax (1111+/-38 w in S vs 886+/-148 w in UT), W (822+/-37 w in S vs 646+/-69 w in UT) and Lamax (16.8+/1.8 mmol x l(-1) in S vs 12.2+/-2.5 mmol x l(-1) in UT). At the end of the test the NAmax values were similar in both groups whereas the Amax were significantly higher in S (7.6 +/- 1.4 nmol x l(-1) in S vs 3.6 +/- 3.2 nmol x l(-1) in UT). This leads to a higher Amax/NAmax ratio for sprinters compared to untrained subjects (0.7+/-0.2 in S vs 0.3+/-0.2 in UT, p < 0.05). As the disappearance of A (estimated by the Amax-A5 difference) was not lower in S (6.4+/1.5 nmol x l(-1) in S vs 1.8+/-4 nmol x l(-1) in UT), the higher Amax values in S might be explained by a greater secretion level of A. Conversely the identical NAmax values in both groups suggested that this kind of exercise induced the same sympathetic input in S and UT. Consequently the higher Amax/NAmax ratio in S argued in favor of a higher responsiveness of the adrenal medulla of sprinters to the same sympathetic input.
Zouhal
H
H
Laboratoire de Physiologie et de Biomécanique de l'Exercice Musculaire, UFR-APS, Université de Rennes, France.
Rannou
F
F
Gratas-Delamarche
A
A
Monnier
M
M
Bentué-Ferrer
D
D
Delamarche
P
P
D000313:Adrenal Medulla / Q000502:physiology*; D000328:Adult; D004837:Epinephrine / Q000097:blood*; D005080:Exercise Test; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D009638:Norepinephrine / Q000097:blood*; D010806:Physical Education and Training; D005082:Physical Exertion / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology; D012420:Running / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology*
D019344:Lactic Acid; D009638:Norepinephrine; D004837:Epinephrine