Effects of Exhaustion and Calcium Supplementation on Adrenocorticotropic Hormone and Cortisol Levels in Athletes
Vedat Cinar & Oktay Cakmakci & Rasim Mogulkoc & Abdulkerim Kasim Baltaci
Abstract The present study was performed to investigate the effects of strenuous exercise
and calcium supplementation on cortisol and adrenocorticotropic hormone levels in athletes
at rest and exhaustion. Thirty male athletes, ages 17–21 years, were enrolled in the 4-week
study. They were divided into three groups as follows: group 1 (n=10): training without
supplementation; group 2 (n=10): training and calcium supplemented, and group 3 (n=10):
calcium supplemented without training. Venous blood samples were obtained for determination
of the hormones. One-month supplementation with calcium does not influence the
cortisol and adrenocorticotropic hormone in athletes, but strenuous exercise results in a
significant increase in their levels with or without supplementation (p<0.05).
During training, exercise causes the psycho- and physiological systems to work jointly to
manage energy use by the body. Hormonal secretion is affected by leptin and stokins,
secreted from fats [1, 2]. Strenuous exercise imposes a stressful condition on the body,
changing its homeostasis. The hypothalamus–hypophysis adrenal axis is also involved in
the protection of homeostasis [3].
There have been several studies investigating the relationship between exercise and hormones
[4, 5]. Cortisol and catecholamine levels are elevated during exercise. Chronic medium-level
elevation of cortisol is observed in well-trained athletes [2, 3]. On the contrary, it was suggested
Biol Trace Elem Res (2009) 127:1–5
DOI 10.1007/s12011-008-8217-5
V. Cinar (*)
High School of Physical Education and Sport, Karaman, Turkey
e-mail: bsyovedat@yahoo.com
O. Cakmakci
High School of Physical Education and Sport, Konya, Turkey
R. Mogulkoc : A. K. Baltaci
Department of Physiology, Meram Medical School, Selcuk University, Konya, Turkey
that daily exercise at low temperatures of about 4°C would result in a reduction of the
cortisol levels [6]. Football players undergoing extreme training during short periods showed a
39% increase of adrenocorticotropic hormone (ACTH) and a 14% increase of cortisol levels.
Cortisol remains elevated for a period of about 40-min after the exercise is suspended [7].
It has been proposed that not only does distortion of hypothalamus–hypophysis
functions influence the way the body responds to exercise [8, 9] but the type of exercise
also has different effects on hormone levels. Cortisol elevation depends on the duration of
the training [10]. Acute, extreme stress greatly increases ACTH, and cortisol secretion [11].
The presence of magnesium, an important cofactor of many enzymes, may also be involved
in these processes due to its participation in energy metabolism [12, 13].
Calcium is lost along with other electrolytes during training by sweating. Replenishment
of these essential minerals via diet or supplementation is recommended, especially calcium
because of its many physiological functions [14–16].
To date, there are no studies measuring the effects of calcium supplementation on the
hormone levels in training athletes. In the present study, experiments were designed to
investigate if calcium might have effect on ACTH and cortisol at rest and exhaustion.
Materials and Methods
Thirty healthy male athletes of ages between 17–21 years voluntarily enrolled in the study.
Before the start of the research protocol, all the subjects gave their informed consent for
participation in the study. The participants were divided into three groups of ten subjects
each and kept under distinct regimes for 4 weeks as follows:
Group 1: Athletes performing training routines for 90 min/day, 5 days a week.
Group 2: Athletes performing training routines for 90 min/day, 5 days a week while
receiving 35 mg/kg/day BW of a calcium gluconate supplement.
Group 3: Athletes receiving 35 mg/kg/day BW calcium gluconate supplement, no
training. All participants tolerated this dose and produced any side effects or
affected general well-being.
The training routines have been described in a previous paper [17].
Analyses of Hormones
The work was performed at the clinical laboratory of the Medical Faculty, Selcuk
University. Two-milliliter blood samples were drawn into ethylene diamine tetraacetic acid
tubes. For the determination of ACTH, we used an Immulate 1000 autoanalyzer. Cortisol
was determined by an Acces Immunoassay system test kit using a Unicel DXI 800
autoanalyzer. Standard reference materials were used for ACTH (reported in pg/mL, Lot
LKAC1) and for cortisol (reported in μg/dl, Lot 517608).
Statistics
The results are expressed as means ± SD. The statistical analysis was carried out with the
SPSS statistical program. The Kruskal–Wallis analysis of variance was used for comparison
between groups and the Mann–Whitney U test was applied to those with p<0.05.
2 Cinar et al.
Results
The ACTH values of all groups are given on Table 1. All groups show the same values at
the beginning of the study (resting before supplementation, Rbs). The same results were
seen for athletes at exhaustion. Exhaustion values before supplementation (Ebs) are
significantly higher than resting values (p<0.05). After supplementation the highest
elevation was seen in the exercise-only group, but the difference was not significant. In the
third (resting after supplementation, Ras) and fourth measurements (exhaustion after
supplementation, Eas) all groups showed no differences in ACTH levels.
Table 1 also gives the cortisol values of all groups. The baseline level is the same for
all groups, but exhaustion causes a significant increase compared to the initial values (p<
0.05) but not so among the three study groups. In the Ras measurement the cortisol levels
increased by the fourth week supplementation and exercise but the elevation was not
significant. The highest increase was determined in the supplemented training athletes. In
subjects at rest, the supplemented and nonsupplemented groups had higher cortisol levels
than the training-only athletes, both in their before and after supplementation (Ebs and
Eas) values.
Discussion
Exercise affects homeostasis by physiological stress, evoking a response from the
autonomous nervous system and the hypothalamus hypophysis adrenal axes and due to
leptin and stokins secreted from fat tissues [1–3]. Similar results were seen when exercise
was performed under ischemic conditions [18]. Under maximum endurance tests, football
players showed a 39% increase of their ACTH and 14% increase of cortisol values. It was
stated that this increase was due to activation of hypophysis and adreno-cortical axes by
stress derived from intense physical activity [19]. Other studies deal with cases of altered
and dysfunctional hypothalamic–pituitary axis [20, 21] and with hormonal changes due to
training under different conditions [22–26].
Our results show that the plasma ACTH and cortisol levels were increased after
strenuous exercise. The level of ACTH had an almost two-fold increase compared to
cortisol. There were no statistical differences in the cortisol increases among groups. The
increase of cortisol here reported is in agreement with the results of several previously
published studies [2–5].
Table 1 Plasma Adrenocorticotropic Hormone (ACTH) and Cortisol Levelsin Athletes Before and After
Supplementation
Condition Group 1 Group 2 Group 3
ACTH (pg/ml) Rbs 29.11±3.12b 28.25±3.86b 27.44±3.22b
Ebs 54.01±3.86a 52.53±5.54a 54.49±5.45a
Ras 31.17±4.08b 29.87±4.25b 28.59±4.75b
Eas 51.54±4.72a 52.19±5.12a 50.89±7.86a
Cortisol (μg/dl) Rbs 15.08±2.65b 15.01±2.98b 15.15±2.52b
Ebs 18.03±3.08a 19.10±3.76a 18.22±1.89a
Ras 16.31±2.54b 17.25±3.50ba 16.42±3.56ba
Eas 17.92±2.88a 19.40±3.02a 18.59±2.78a
a,b,c Differences among values in the same column
Effects of Exhaustion and Calcium Supplementation 3
Our results establish that 4-week supplementation with calcium has no significant effect
on the hormonal response of the body to strenuous exercise because there were no
significant differences in the ACTH and cortisol levels among the study groups, at rest or
after exhaustion.
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Effects of Exhaustion and Calcium Supplementation 5
