Biology o Spo , Vol. 24 No4, 2007
.
PROLACTIN RESPONSES TO STRESS INDUCED BY A COMPETITIVE
SWIMMING EFFORT
L. Ca asco Páez1, G.T. Luque1, C.V. Gu ié ez2, C.M. Ol as2
1Dep . o Heal h and Spo Sciences, Ca holic Uni e si y o Mu cia, Spain; 2Dep .
o Nu sing, Uni e si y o G anada, Spain
Abs ac . Pu pose: The aim o he p esen s udy was o in es iga e he changes in
p olac in (PRL) plasma concen a ions induced by compe i i e swimming p ac ice.
Me hods: Twen y- h ee males, 13 ained swimme s (expe imen al g oup) and 10
seden a y and heal hy s uden s (age-ma ched con ol g oup) ook pa in his
in es iga ion. The swimme s we e assessed a h ee poin s: basal condi ions, p e-
and pos -swimming compe i ion (100 m ees yle), whe eas subjec s om he
con ol g oup only unde ook he basal ial. The a iables analysed we e: se e al
body composi ion measu es, anxie y le el (STAI ques ionnai e), PRL and lac ic
acid concen a ions. Resul s: No s a is ical di e ences we e obse ed in PRL basal
le els be ween g oups. An e iden PRL esponse o p e-compe i ion psychological
s ess was obse ed in he expe imen al g oup, since he PRL plasma
concen a ion ose om 4.02±0.53 ng/ml (basal condi ions) o 5.52±0.53 ng/ml
(p≤0.05). The PRL esponse o he compe i i e e o p oduced an impo an
inc ease in i s plasma concen a ion (10.07±1.59 ng/ml), showed s a is ical
di e ences om p e-compe i ion (p≤0.01) and om basal condi ions (p≤0.001). A
signi ican ise in plasma lac a e le els jus a he end o he e o was ound,
al hough i did no co ela e wi h PRL le els in he same si ua ion. Conclusion:
While we obse ed a ema kable esponse o PRL o psychological and
physiological s ess induced by a sho e m compe i i e e o in swimming, no
changes in PRL basal le els we e exhibi ed wi h swim aining. Mo e esea ch is
needed o cla i y hese indings. (Biol.Spo 24:311-323, 2007)
Key Wo ds: Anxie y - Ho monal elease - Anae obic exe cise - Compe i ion
In oduc ion
The esponses and adap a ions o se e al ho mones denomina ed “s ess
ho mones” which a e sec e ed om an e io pi ui a y gland, can gi e an in eg a ed
Rep in eques o: D . Luis Ca asco Páez.Mu illo 13, 1ºB.03600 Elda, Alican e, Spain
Tel: 00 34 968278824, Fax: 00 34 968278658; E-mail: [email p o ec ed]m.edu
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L. Ca asco Páez e al.
Biol.Spo 24(4), 2007
312
in o ma ion abou psychological and soma ic s ess ha a hle es can o expe ience
in a compe i i e e o .
P olac in (PRL) is a polypep idic ho mone o a single chain wi h 198
aminoacids, s uc u e e y simila o he human g ow h ho mone (hGH). Thei
p incipal biological ac ions a e mamo h opic and gonado h opic, al hough
no mally se e al ex e nal s imulus can o imp o e he PRL sec e ion. S ess, om
psychological o soma ic o igin, is one o his s imulus [1].
As o soma ic s ess induced by exe cise, se e al au ho s ha e ocused hei
a en ion in he s udy o PRL esponses o a maximal e o s, unde anae obic
ene gy sou ce suppo . In his sense, ises o e 100% om he PRL basal le els
ha e been ound a e a p og essi e and maximal e o [7,22]. In o he
in es iga ion, he esponse o PRL o an in e al and exhaus i e exe cise was
analysed in ained subjec s. Jus a he end o he e o PRL plasma concen a ions
ose 230% abo e o basal le els [17]. Also, a impo an inc ease in PRL plasma
concen a ions a e an exhaus i e exe cise was ound, al hough cu iously he peak
concen a ion was eached 60 min a e exe cise [14]. Howe e , anae obic e o s,
o sho du a ion and high in ensi y, like a 60 s o consecu i e e ical jumps,
leaded o inc ease PRL plasma concen a ion, e en hough no s a is ical
signi icance was ound [5].
On he o he hand, an impo an numbe o in es iga ions o analyse PRL
esponse ela ed o ae obic exe cises ha e been de eloped. In his sense, he
al e a ions in PRL plasma concen a ion in long dis ance unning (hal ma a hon
and ma a hon) ha e been analysed. In his s udies, a signi ican inc ease in PRL
concen a ion was obse ed a he end o exe cise [25,30]. In spi e o ha , he e
a e da es which o e some con o e sy o he indica ed be o e, since a e o
examine PRL plasma concen a ions in 11 male ained a hle es be o e, du ing and
a he end o a unning ace o 110 km, no a ia ions we e egis e ed [15].
Al hough wi h some excep ions, e e y hing poin s o ae obic and anae obic
exe cises a e p esen ed like a su icien s imulus o induce PRL sec e ion. In ac ,
a e 60 min o con inuous ae obic exe cise and a e 60 min o in e mi en
anae obic exe cise, he PRL plasma concen a ions o nine subjec s who
pa icipa ed in his in es iga ion ose signi ican ly abo e he basal le els [18].
Ano he objec i e o pu sue in his ype o in es iga ions is he es ablishmen o
a minimal in ensi y o e o om which he PRL esponse and/o elease o PRL
occu . In he i s in es iga ions de eloped wi h his aim, he anae obic h eshold
was es ablished such as minimal in ensi y necessa y o o induce he PRL esponse
[9]. In he nex in es iga ions his in ensi y was loca ed be ween 70 and 80% o
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P olac in and s ess in compe i i e swimming
Biol.Spo 24(4), 2007
313
VO2máx, demons a ing ha exe cises o mino in ensi y a e unable o al e PRL
plasma le els, o e en can lead o educe hem [12,21].
By he o he hand, and ela ed wi h s ess om psychological sou ce, he e is no
e idence ha his ype o s ess would o s imula e he PRL esponse and o cause
an inc ease o i s plasma concen a ion. This is ga he ed om he ew s udies in
which he esponses o PRL o psychological s ess ela ed o compe i ion ha e
been e alua ed [25,29].
A e his p eceden s, he aims o he p esen in es iga ion a e: a) o de e mine
he psychological s ess (anxie y) gene a ed by a highly demanding e o –an
o icial swimming compe i ion–, and assessing he PRL esponse o his e en , and
b) o de e mine he plasma PRL eac i i y o he soma ic s ess induced by his
maximal and sho du a ion e o .
Ma e ials and Me hods
Thi een na ional le el male swimme s, all o whom we e specialis s in
swimming dis ances o 100 and 200 m wi h an expe ience o a leas 6 yea s in
sys ema ic aining (expe imen al g oup) and en heal hy male s uden s (age-
ma ched con ol g oup) ook pa in his s udy. In o med w i en consen was
ob ained om all pa icipan s, and he p ojec was app o ed by he e hical
commi ee o he Uni e si y o G anada. Gene al and an h opome ic
cha ac e is ics o he subjec s a e p esen ed in Table 1.
Table 1
Subjec cha ac e is ics
Age
(y )
Heigh
(cm)
Weigh
(kg)
BMI
(kg/m2)
Body a
(%)
Expe imen al
18.62
±0.78
174.95
±1.80
65.11
±2.14
21.28
±0.66
10.75
±1.00
Con ol
19.10
±0.82
171.55
±2.24
74.07
±4.19
25.09
±1.15**
21.59
±1.93***
Da a ep esen means ± SEM
**p≤0.01, ***p≤0.001 o Mann-Whi ney es compa ing expe imen al and con ol
g oups
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L. Ca asco Páez e al.
Biol.Spo 24(4), 2007
314
The swimme s unde wen h ee expe imen al ials. In he i s ial, he
swimme s and he con ol g oup, we e es ed in basal condi ions (subjec s we e
asked o abs ain om s enuous physical ac i i y o a leas 24 h and o as o 8 h
be o e es ing). Upon a i al o he labo a o y, an h opome ical and body
composi ion pa ame e s: heigh , weigh , body mass index (BMI), and body a
pe cen age (bioelec ic impedance, OMRON BF300 analyse ) we e egis e ed, and
a blood sample (10 mL) was ob ained om he an ecubi al ein. Subsequen ly, all
subjec s comple ed he S a e - T ai Anxie y In en o y (STAI) [28]. One week
la e , a app oxima ely he same ime o day (be ween 8:30 and 10:00 am), in he
same es ing and as ing condi ions o he i s ial, he swimme s pa icipa ed in
an o icial swimming compe i ion. Be o e compe i ion, and a e 10 min. o es in
he swimming pool, a blood sample (10 mL) was ob ained om swimme s, and
hey comple ed he STAI ques ionnai e (s a e e sion). This was ollowed by a
s anda d wa m-up (20 min. easy swimming). Immedia ely a e he wa m-up
pe iod, he swimme s compe ed in hei espec i e 100m ees yle hea s. Time o
comple e his dis ance was he mean o ha egis e ed by wo o icial imekeepe s.
Immedia ely a e each hea (1-2 min. pos -exe cise) he swimme s we e subjec ed
o ano he blood ex ac ion (10 mL), and comple ing he STAI ques ionnai e (s a e
e sion). The en i onmen condi ions egis e ed in he compe i ion we e he
ollowing: 27.5º C o wa e empe a u e, 29.4º C o ai empe a u e and 58% o
ela i e ai humidi y (simila o i s ial condi ions).
Each blood sample was di ided in wo aliquo s o 5 mL (EDTA K2 ubes wi h
50 µl o ap o inin: SIGMA A6279). One o he aliquo s was des ined o
haema ological analysis (Coul e JT3 analyse ), and plasma was ob ained om he
emaining aliquo . Biochemical pa ame e s measu ed in plasma samples we e: PRL
concen a ion (RIA, Radim-Ibé ica. In a-assay a ia ion: 4%; in e -assay
a ia ion: 6%), o al p o ein concen a ion (elec opho ome y; Hi achi 737
au oanalyse , Bohe inge -Mannheim) and lac a e concen a ion (enzyma ic
de e mina ion and e lec ance pho ome y me hod, Accuspo ®,
Roche/Boeh inge -Mannheim). Haemog am (haemoglobin concen a ion and
haema oc i alue) was pe o med o calcula e he possible changes in plasma
olume (PV) ha could al e he esul s o he biochemical analysis [13].
Mo eo e , he plasma o al p o ein concen a ion was de e mined in o de o
co obo a e hese changes in PV.
Da a a e exp essed as mean ± s anda d e o o he mean (SEM). Non-
pa ame ic me hods we e used in s a is ical analysis. F iedman es was used o
compa e he expe imen al ials, and Mann-Whi ney es was used o compa e he
a iables be ween he expe imen al and he con ol g oup. Fu he mo e, linea
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P olac in and s ess in compe i i e swimming
Biol.Spo 24(4), 2007
315
eg ession analysis was pe o med, and Pea son co ela ion coe icien was
calcula ed o de e mine he ela ionship be ween a iables. In all cases, s a is ical
signi icance was es ablished a an alpha le el o 0.05.
Resul s
No signi ican di e ences we e obse ed o plasma PRL and lac a e
concen a ion measu ed in basal condi ions be ween he expe imen al and con ol
g oups. Simila ly, no signi ican di e ences we e obse ed in STAI sco es
egis e ed in basal condi ions be ween g oups (Table 2).
Table 2
Plasma PRL and lac a e concen a ions and STAI sco es egis e ed in basal
condi ions
PRL
(ng/mL)
Lac ic acid
(mmol/L)
STAI sco es
S a e
T ai
Expe imen al
4.02±0.53
1.77±0.07
18.46±2.79
21.77±3.02
Con ol
4.36±1.09
1.72±0.07
1.72±0.07
22.10±3.63
Da a ep esen means ± SEM.
A signi ican inc ease in plasma PRL concen a ion (p≤0.05) was obse ed in
p e-compe i ion compa ed wi h basal condi ions (5.52±0.53 s 4.02±0.53 ng/mL,
espec i ely). Howe e , plasma lac a e concen a ion in p e-compe i ion si ua ion
was simila o he concen a ion obse ed in basal condi ions (1.89±0.04 s
1.77±0.07 mmol/L, espec i ely) (Fig. 1 and Fig. 2). The STAI sco es in p e-
compe i ion si ua ion (24.5±3.1) we e signi ican ly highe han hose egis e ed in
basal condi ions (Fig. 3), al hough no s a is ical ela ionship was es ablished
be ween PRL plasma concen a ions and p e-compe i i e STAI sco es ( =-0.20;
p=0.95).
Time o comple e he 100 m ees yle was 61.47±1.98 s. In e es ingly, e en
hough he compe i ion was o such a b ie du a ion, one inding o his s udy was
he dec ease in PV obse ed a e he e o . This dec ease was 11.42±1.28 %
compa ed o p e-compe i ion alues. In i s compu a ion, he haemoglobin
concen a ions as well as he haema oc i alues p e- and pos -compe i ion we e
conside ed. The dec ease in PV was suppo ed by a s a is ically signi ican inc ease
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L. Ca asco Páez e al.
Biol.Spo 24(4), 2007
316
o he plasma o al p o ein concen a ion obse ed immedia ely a e he
compe i i e e o (Table 3). We used his indi idual pe cen change o co ec
each o he ho monal and biochemical de e mina ions.
Table 3
Biochemical pa ame e s and changes in plasma olume
O icial compe i ion (100 m ees yle)
P e – compe i ion
Pos – compe i ion
To al plasma p o ein (g/dL)
7.77±0.11
8.55±0.11***
Haemoglobin (g/dL)
15.65±0.22
16.54±0.21
Haema oc i (%)
47.27±0.59
50.68±0.66
PV change (%)
- 11.42±1.28
Da a ep esen means ± SEM
The PRL esponse o he compe i i e e o p oduced a signi ican inc ease in
he ci cula ing le els o his ho mone, eaching mean alues o 10.07±1.59 ng/mL.
These alues we e signi ican ly highe han he ones ound in basal condi ions and
hose obse ed in he p e-compe i ion si ua ion (Fig. 1). Simila inc eases we e
obse ed in plasma lac a e. Mean alues o 9.72±0.53 mmol/L we e egis e ed
pos -compe i ion. These alues we e also signi ican ly highe han hose ound in
basal condi ions and obse ed be o e he swim (Fig. 2). Howe e , eg ession and
co ela ion analyses showed no ela ionship be ween PRL and plasma lac a e
concen a ions in pos -compe i ion si ua ion ( =0.02; p=0.95). On he o he hand,
he pos -compe i ion anxie y alues (22.7±3.2), we e sligh ly lowe han hose
ound be o e he beginning o he compe i i e swimming e o , and sligh ly highe
han basal le els. No signi ican di e ences we e obse ed wi h ega d o hese
STAI sco es (Fig. 3). A signi ican co ela ion (p=0.04) was ound be ween PRL
plasma concen a ions and STAI sco es a e he swim, al hough he alue (0.57)
showed a weak ela ionship.
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P olac in and s ess in compe i i e swimming
Biol.Spo 24(4), 2007
317
Fig. 1
Swimme s’ plasma PRL concen a ions measu ed in all expe imen al ials. *p≤
0.05; ***p≤ 0.001 compa ed wi h basal condi ion; ++p≤0.01 compa ed wi h p e-
compe i ion ial
Fig. 2
Swimme s’ plasma lac a e concen a ions measu ed in all expe imen al ials.
***p≤ 0.001 compa ed wi h basal condi ion; +++p≤ 0.001 compa ed wi h p e-
compe i ion ial
0
2
4
6
8
10
12
14
P e- Pos -
Basal Compe i ion
PRL (ng/mL)
*
***
++
0
2
4
6
8
10
12
P e- Pos -
Basal Compe i ion
Lac ic acid (mmol/L)
***
+++
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L. Ca asco Páez e al.
Biol.Spo 24(4), 2007
318
Fig. 3
Swimme s’ s a e – anxie y le els acco ding o he sco es ob ained in he STAI
ques ionnai e in he h ee expe imen al si ua ions. **p≤ 0.01 compa ed wi h basal
condi ions
Discussion
F om a psychosoma ic pe spec i e, he e a e ew si ua ions which can p oduce
al e a ions such as hose obse ed when an a hle e has o unde ake a maximal
e o in compe i ion. In he esponse o hose al e a ions he endoc ine sys em is
p omp ly ac i a ed, and he hypo halamic-pi ui a y-ad enoco ical (HPA) axis
plays a key ole in he esponse o s ess, whe he his s ess has a soma ic o a
psychological o igin (27).
PRL is eleased in o he blood in esponse o di e en ypes o s ess. Fo his
eason, i s possible ha he analyses o PRL plasma le els in basal si ua ion can o
e lec an adap a ion o s ess induced by swimming aining. PRL plasma
concen a ions ob ained in basal condi ions o bo h g oups in his in es iga ion a e
wi hin he ange p oposed as no mal e e ence alues o adul s (8) and a e e y
simila o hose egis e ed in o he s udies (10).
Wi h his esul s, and ake in o accoun ha in a la ge numbe o in es iga ions
he PRL basal concen a ions o ained and seden a y subjec s a e e y simila
[11,21,25] we concluded ha his ho mone le els a e no use ul o e alua e he
adap a ion o ch onic s ess induced by swimming aining.
0
5
10
15
20
25
30
P e- Pos -
Basal Compe i ion
STAI sco es
**
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P olac in and s ess in compe i i e swimming
Biol.Spo 24(4), 2007
319
The mean plasma lac a e alues in basal condi ions a e highe han hose
epo ed in o he s udies wi h swimme s [3]. These alues a e, howe e , wi hin he
ange desc ibed by he a o emen ioned au ho s (0.9-2.3 mmol/L).
Ano he impo an aspec o conside is he possible exis ence o psychological
al e a ions (anxie y) in he subjec s e alua ed, since his could be he main igge
o he PRL elease. Once he sco es om he STAI ques ionnai e, wi h ega d o
ai -anxie y and s a e-anxie y we e analysed, and a e compa ing hem wi h he
e e ence scale p o ided by Spielbe ge e al. [28] o he spanish popula ion, we
conclude ha he sco es we e close o he mean o his popula ion. Al hough
se e al s udies ha e epo ed highe ai - anxie y le els in emale swimme s han
in ama eu swimme s and seden a y sex and age ma ched g oups [24], compe i i e
swimming p ac ice no seems o ha e an e ec on swimme s e alua ed in he
p esen in es iga ion.
An impo an PRL esponses in swimming compe i ion we e egis e ed. We
ound a signi ican inc ease (40%,p≤0.05) in PRL plasma concen a ion be o e
aking pa in he swimming compe i ion compa ed o basal alues. These esul s
show how PRL esponded o a si ua ion whe e some deg ee o psychological s ess
(anxie y) was gene a ed. An inc ease in he s a e-anxie y sco es compa ed wi h he
sco es ob ained in he basal condi ion (p≤0.001) e i ied his esponse. These
inc eases in he anxie y le els a e in acco dance wi h hose p e iously epo ed
[20], al hough in hese s udies he p e-compe i ion s a e-anxie y le els ound in he
swimme s we e highe han he le els we ha e eco ded. Ne e heless, he e is no
doub abou he ele ance o he swimming compe i ion analysed in ou
in es iga ion since p o oked an impo an ise in swimme ’s anxie y le els. In his
sense, he ele ance o compe i ion can be conside ed as a decisi e ac o in his
ype o in es iga ions [23]. Ou esul s a e opposed o hose epo ed by se e al
au ho s whom no ound PRL esponses o p e-compe i ion anxie y [25,29]. As
expec ed, he plasma lac a e alues in he p e-compe i ion si ua ion (samples aken
be o e wa ming-up) showed no signi ican di e ences om he basal alues.
Immedia ely a e inishing he swimming maximal e o (pos -compe i ion),
signi ican inc eases in PRL plasma le els we e egis e ed. These alues we e up o
150% highe han basal concen a ions (p≤ 0.001) and 82% highe han hose ound
p e-compe i ion (p≤0.01). This la e pe cen change could indica e he ex en o
which he physical (soma ic) e o i sel accoun s o he PRL esponse. Al hough
i ha e ound PRL esponses o p og essi e and maximal e o s [10,18,31], ou
indings, opposed o hose ob ained in p e ious s udies [5], show an e iden PRL
esponse o high-in ensi y, sho - e m anae obic exe cise.
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