Plasma growth hormone, cortisol and testosterone responses to repeated and intermittent ergometer exercise at different pedalling rates.
Journal Title: Biology of Sport - Year 2003, Vol 20, Issue 2
Abstract
The aim of this work was the evaluation of the hormonal response to the repeated and intermittent exercises at different rates. Nine students of the physical education (age: 24.1±0.39 years; body mass: 81.2±10.17kg; height: 182.1±7.32 cm; VO2max – 4.121±0.697 l O2/min) performed in the laboratory conditions series of 5 efforts on the cycle ergometer lasting for 3 min with the loading of 250 W and divided with 2 min intervals. In the first day the pedalling rate amounted to 45circ/min (W45), in the second day to 80circ/min (W80). In both cases the work performed (225 kJ), time lasting and power of efforts were the same. The growth hormone (GH), testosterone (T) and cortisol (C) were denoted in the capillary blood taken with the immuno-enzymatic methods from the finger tip. The anabolic – catabolic index (T/C) was also determined. The blood acid – alkali balance parameters were registered using the gas analyser Ciba-Corning 248. The blood was taken: before effort, after third effort (13 min), immediately after fifth effort (23 min) and 30 min after the test. Series of the repeated and intermittent exercises caused the significant (P<0.05) lowering of the capillary blood pH, respectively from: 7.392–7.409 before effort to: 7.316±0.092 (W45) and 7.287±0.068 (W80) after fifth effort. The differences between W45 and W80 were statistically insignificant. The highest concentrations of GH and T were noticed after all efforts in both series. The T concentration grew significantly, similarly in both series: W45 –5.8±1.93 and W80 –5.9±1.59 ng/ml from the restful level ≈ 4.6 ng/ml. The significant differentiation of the response on different pedalling rates was observed in case of GH. The highest GH concentration amounted to: 7.7±5.43 ng/ml after W45 and after W80 to: 16.8±6.68 ng/ml. The GH concentration changes presented lower level (P<0.05) during work performed with the smaller rate i.e.: 45circ/min. As regards cortisol (C), the significant increase until the 30th min after effort occurred after the series with the rate of 80 circ/min (increase from: 158.8±52.55 ng/ml before to 236.1±102.43 ng/ml after) unlike in the series with the rate of 45circ/min where the concentration of C, 30 min after effort, presented level close to the level reached before the test (181.6±62.50 ng/ml before effort and 161.5±102.62 ng/ml in 13th min of the rest). The effort test with the higher pedalling rate caused the significant lowering of the T/C index unlike the W45 when its growth in the third and thirteenth min of the repose was observed (P<0.05). Negative correlations between the highest GH concentration in both series and the decrease of the blood pH (r= -0.569; P<0.01); a GH peak and the T/C index (r= -0.819; P<0.001 ) and the examined VO2max and the GH peak (r= -0.753; P<0.05) were determined. As a conclusion it may be stated that the rate/speed of performed work influences hormonal responses through the increase of cortisol and growth hormone concentrations alongside the similar level of the acid-alkali blood balance disturbances during work with the higher pedalling rate. The anabolic – catabolic balance disturbances (decrease of the T/C index ) present strong impulse for the growth hormone secretion.
Authors and Affiliations
BH Opaszowski, K Buśko
Keywords
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