Performance and thermoregulatory effects of chronic bupropion administration in the heat.
The combination of acute dopamine/noradrenaline reuptake inhibition (bupropion; BUP) and heat stress (30 degrees C) significantly improves performance (9%). Furthermore the maintenance of a higher power output resulted in the attainment of significantly higher heart rates and rectal temperatures--above 40 degrees C--in the BUP trial compared to the placebo trial. Since BUP is an aid to cease smoking that is taken for longer periods, question remains if similar performance and thermoregulatory effects are found following administration of BUP over several days (10 days). The purpose of the present study was to examine the effects of chronic BUP on exercise performance, thermoregulation and hormonal variables in the heat. Eight trained male cyclists participated in the study. Subjects completed two trials consisting of 60 min fixed intensity exercise (55% W (max)) followed by a time trial (TT) in a double-blind randomized crossover design. Exercise was performed in 30 degrees C. Subjects took either placebo (PLAC) or BUP (Zyban) for 3 days (150 mg), followed by 300 mg for 7 days. Chronic BUP did not influence TT performance (BUP 40'42'' +/- 4'18''; PLAC 41'36'' +/- 5'12''), but significantly increased core temperature (P = 0.030). BUP significantly increased circulating growth hormone levels (PLAC: 9.8 +/- 5.8 ng L(-1); BUP: 13 +/- 6.8 ng L(-1); P < 0.008).


CONCLUSIONS
Chronic BUP did not influence TT performance in 30 degrees C and subjects did not reach core temperature values as high as observed during the acute BUP study. It seems that chronic administration results in an adaptation of central neurotransmitter homeostasis, resulting in a different response to the drug.
Roelands
Bart
B
Department of Human Physiology and Sports Medicine, Faculty of Physical Education and Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium.
Hasegawa
Hiroshi
H
Watson
Philip
P
Piacentini
Maria Francesca
MF
Buyse
Luk
L
De Schutter
Guy
G
Meeusen
Romain
R
D000220:Adaptation, Biological / Q000502:physiology; D000328:Adult; D001833:Body Temperature Regulation / Q000187:drug effects* / Q000502:physiology*; D016642:Bupropion / Q000008:administration & dosage*; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage; D004334:Drug Administration Schedule; D015444:Exercise / Q000502:physiology; D005080:Exercise Test; D013006:Growth Hormone / Q000097:blood; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006358:Hot Temperature; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000187:drug effects* / Q000502:physiology*
D018765:Dopamine Uptake Inhibitors; D016642:Bupropion; D013006:Growth Hormone