The effect of low-carbohydrate diet on the pattern of hormonal changes
during incremental, graded exercise in young men.
Langfort JL, Zarzeczny R, Nazar K, Kaciuba-Uscilko H.
Source
Department of Applied Physiology, Medical Research Centre, Polish Academy of
Sceinces, 5 Pawinskiego Str., PL-02-106 Warsaw, Poland.
Abstract
The purpose of this study was to discover whether severe dietary
carbohydrate (CHO) restriction modifies the relationship between exercise
intensity and hormonal responses to exercise. Changes in the plasma
adrenaline (A), noradrenaline (NA), growth hormone (hGH), testosterone (T),
and blood lactate (LA) during an incremental exercise performed until
volitional exhaustion were determined in 8 physically active volunteers
after 3 days on low CHO (< 5% of energy content; L-CHO) and isocaloric mixed
(M) diets. Following L-CHO diet, the basal plasma A, NA, and hGH
concentrations were increased, whilst T and LA levels were decreased. During
exercise all the hormones increased exponentially, with thresholds close to
that of LA. Neither the magnitude nor the pattern of the hormonal changes
were affected by L-CHO diet except the NA threshold, which was lowered.
Blood LA response to exercise was diminished and LA threshold was shifted
towards higher loads by L-CHO diet. It is concluded that restriction of CHO
intake (a) does not affect the pattern of changes in plasma A, hGH, and T
concentrations during graded exercise but lowers NA threshold, indicating
increased sensitivity of the sympathetic nervous system to exercise
stimulus; (b) alters the basal and exercise levels of circulating hormones,
which may have an impact on the balance between anabolic and catabolic
processes and subsequently influence the effectiveness of training

 
 
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