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Unlabelled: 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).Discussion/conclusion: 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. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare in amateur swimmers the critical swimming velocity (CV) with the swimming velocity corresponding to a blood lactate concentration of 4 mmol l ( V). Ten amateur swimmers volunteered for this study (six men, age 22.3 ± 2 years; four women, age 21.3 ± 1 years) and performed a 7 × 200-m swimming test (at 70%, 75%, 80%, 85%, 90%, 95% and 100% of their 200-m best time) with 5 min rest between each repetition. Blood lactate concentration was determined after each repetition. V was determined from the speed-lactate curve. In order to calculate CV, the best front-crawl swimming results over 50, 100, 200 and 400 m were used. CV was expressed as the slope of the linear relationship between time and distance. Swimming velocities obtained with the two tests (CV 1.086 ± 0.151 m s; V 1.087 ± 0.128 m s) were positively and significantly correlated ( r = 0.93, p < 0.05) and no significant differences were found. A Bland-Altman plot showed a good agreement between the two measurement methods. These results confirm that the CV seems to be a valid and noninvasive method for also determining training intensities and monitor endurance capacity in less-experienced athletes. [ABSTRACT FROM AUTHOR]