Growth-Retarding Effect of "Cardio"-Training is not Prevented by BCAA Supplementation. Endurance-Trained Rats Still -3% Smaller than Age-Mates.
|Image 1: Haile Gebrselassie,|
probably the greatest distance
runner in history, set 27 world
records; is his sort stature a
result of too much "cardio"
(image by Alexxx86)
For 5 weeks, Patricia Lopez de Campos-Ferraz and her colleagues, put 32 male Wistar rats (21 days old) on one of four experimental protocols:
- 45mg/kg BCAA + swimming - Sup/Ex
- Standard chow + swimming - Ctrl/Ex
- 45mg/kg BCAA + sedentary - Sup/Sed
- Standard chow + sedentary - Ctrl/Sed
|Figure 1: Effect of treatment (BCAA + "cardio" or "cardio" only) on cartilage weight, skull-to-tale length and tibia length in adolescent rats (data adapted from Campos-Ferraz. 2011)|
|Image 2: If the Hulk loves HIIT,|
he probably has a healthier
heart than many marathon
runners (image from
|Figure 2: Liver and muscle glycogen content in the four groups (data adapted from Campos-Ferraz. 2011)|
|Figure 3: Muscle protein and RNA content in the four groups (data adapted from Campos-Ferraz. 2011)|
[t]his is in accordance with another study, in which oral administration of 270mg leucine to rats enhanced phosphorylation of the eu-karyotic initiation factor (eIF) (4F-BP1), but no differences in protein synthesis were found in the liver, which led them to conclude that the translation of mRNA is disjointed from the rates of total protein synthesis but is related to the degree of SK61 phosphorylation (Anthony et al., 2001).While this may be the case, Campos-Ferraz et al. simply ignore that their "exercise" (I am inclined to say "torture") program was devoid of the most important stimulus of muscle growth, which is muscular overload - what is really surprising is thus not that the rats did not turn into hulk-like muscle-monsters, but rather that the supplemented rats (Sup/Ex) had a statistically non-significant, yet slightly reduced increase in muscle protein content (+3.92mg% vs. +5.52mg%) compared to their exercised peers (Ctrl/Ex) - despite a +23% greater increase in muscle RNA.
Interestingly, we see diametrically opposed effects in the sedentary group, where muscle RNA content is identical, and the BCAA group (Sup/Sed) has a slightly higher muscle protein content (cf. figure 3). So that, after all, we have come full circle to the detrimental effects of arduous "cardio"-training on adolescents ;-)