PMID- 11856966
OWN - NLM
STAT- MEDLINE
DCOM- 20020822
LR  - 20191025
IS  - 0958-0670 (Print)
IS  - 0958-0670 (Linking)
VI  - 87
IP  - 2
DP  - 2002 Mar
TI  - Hyperprolactinaemia during prolonged exercise in the heat: evidence for a 
      centrally mediated component of fatigue in trained cyclists.
PG  - 215-26
AB  - Several lines of evidence suggest that central serotoninergic neurons may mediate 
      fatigue signals during prolonged exercise. In this study we examined the effects 
      of diet and ambient temperature on peripheral modulators and indices of 
      serotoninergic function and their relationship to exercise performance. Six 
      well-trained cyclists participated, in randomised order, in two diet and exercise 
      regimens each lasting 8 days and comprising four cycle tests to exhaustion at 70 
      % of maximum oxygen uptake. On days 1 and 5, subjects exercised to exhaustion to 
      deplete muscle glycogen. For 3 days after the first depletion trial a diet 
      providing 10 % of energy in the form of carbohydrate (CHO) was consumed (low 
      CHO), and for 3 days after the second depletion trial a diet providing 80 % (high 
      CHO) of energy as CHO was consumed, and each diet was followed by a performance 
      trial at the same ambient temperature, either 10 degrees C or 30 degrees C (days 
      4 and 8). This schedule was repeated after 1 week, but performance trials were 
      carried out at the other ambient temperature. In the cold, cycling time increased 
      (P < 0.01) from 89.2 (78.0-129.5) min (median (range)) in the low CHO trial to 
      158.2 (116.9-165.6) min in the high CHO trial. In the heat, cycling time 
      increased from 44.0 (31.8-51.4) min in the low CHO trial to 53.2 (50.2-82.2) min 
      on the high CHO trial (P = 0.02). The serum prolactin (Prl) concentration was 
      higher at exhaustion during the two trials in the heat than in the two trials in 
      the cold. Serum Prl levels were unrelated to the purported peripheral modulators 
      of serotoninergic function (plasma concentrations of total tryptophan (Trp), free 
      Trp, branched-chain amino acids (BCAAs), free Trp/BCAA ratio and total Trp/BCAA 
      ratio) but were significantly related to the rectal temperatures measured during 
      the two trials in the heat. This finding provides indirect evidence that the 
      serotoninergic system may be involved in fatigue during exercise under conditions 
      of heat stress.
FAU - Pitsiladis, Y P
AU  - Pitsiladis YP
AD  - Department of Biomedical Sciences, University Medical School, Aberdeen AB25 2ZD, 
      UK.
FAU - Strachan, A T
AU  - Strachan AT
FAU - Davidson, I
AU  - Davidson I
FAU - Maughan, R J
AU  - Maughan RJ
LA  - eng
PT  - Journal Article
PL  - England
TA  - Exp Physiol
JT  - Experimental physiology
JID - 9002940
RN  - 0 (Amino Acids)
RN  - 0 (Fatty Acids, Nonesterified)
RN  - 333DO1RDJY (Serotonin)
RN  - 9002-62-4 (Prolactin)
SB  - IM
MH  - Adult
MH  - Amino Acids/blood
MH  - Bicycling/physiology
MH  - Body Temperature/physiology
MH  - Body Temperature Regulation/*physiology
MH  - Diet
MH  - Energy Metabolism/physiology
MH  - Fatigue/*physiopathology
MH  - Fatty Acids, Nonesterified/blood
MH  - *Hot Temperature
MH  - Humans
MH  - Hyperprolactinemia/*physiopathology
MH  - Neurons/physiology
MH  - Physical Exertion/*physiology
MH  - Prolactin/blood
MH  - Rectum
MH  - Serotonin/physiology
EDAT- 2002/02/22 10:00
MHDA- 2002/08/23 10:01
CRDT- 2002/02/22 10:00
PHST- 2002/02/22 10:00 [pubmed]
PHST- 2002/08/23 10:01 [medline]
PHST- 2002/02/22 10:00 [entrez]
AID - EPH_2342 [pii]
AID - 10.1113/eph8702342 [doi]
PST - ppublish
SO  - Exp Physiol. 2002 Mar;87(2):215-26. doi: 10.1113/eph8702342.