Effects of running on hormonal growth factors
| Autor: | Blostein, Ashley C. |
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| Rok vydání: | 1993 |
| Předmět: | |
| Zdroj: | Virtual Press. |
| Popis: | To determine the influence of running on certain blood-born parameters that are involved in bone metabolism, serum levels of calcium, alkaline phosphatase (ALP, a marker of bone formation), growth hormone (hGH), and parathyroid hormone (PTH), were analyzed in 10 male subjects following a 40 min. run at 70% VO2max. Each trial was preceeded by 1 day of inactivity, a 8-12 hr. fast, and drawing of a baseline blood sample by venipuncture. All other blood samples were taken via an indwelling catheter which was inserted in an antecubital vein immediately following the completion of the exercise bout. When the catheter was in place, an "immediate post" sample was drawn. Subsequent samples were taken at 1, 2, 3, 4, 5, 10, 15, 20, 30, 45, and 60 min. after the immediate post sample. Analysis of serum calcium concentrations demonstrated that levels were significantly elevated by 12% following exercise, going from a fasted level of 9.7 ± .53 mg/dl to post-exercise levels of 11.8 ± .73 mg/dl. Serum calcium remained elevated during the first 4 min. following exercise. By 5 min. post-exercise, calcium levels dropped to levels that were significantly lower than the post-exercise sample. However, serum alkaline phosphatase did not change significantly following exercise, as the values remained within normal range throughout the experimental period. Concentrations tended to decrease over time but were not significantly lower than the preor post-exercise levels by the end of the sampling period. Serum concentrations of hGH were more than doubled following a single bout of exercise, going from 4.0 ± 0.98 ng/ml before exercise to 8.8 ± 1.6 ng/ml immediately post-exercise. Following this initial rise, hGH progressively declined and returned to baseline values by 30 min. post-exercise. The concentrations of PTH did not change significantly following exercise. The postexercise sample tended to be higher than baseline values but were not significantly different. The results presented here indicate that an exercise bout 40 min. at 70% V02max results in an elevation of serum calcium and hGH, but does not alter PTH secretion or ALP activity. The data presented in this study indicate that the temporary rise in calcium following exercise is unrelated to PTH. It is hypothesized that the increase in calcium that we observed is attributable to lactate accumulation that would result from an exercise bout of this nature. The buildup of lactic acid and drop in pH causes a dissolution of the crystaline calcium hydroxyapatite compartment of the skeleton, thus causing an increase in ionized calcium. It is not known whether a single bout of exercise can influence hormonal secretion to a sufficient degree to affect bone density, but the hormonal changes demonstrated here could be involved in long-term effects of training. School of Physical Education |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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