by Robh » Thu Apr 30, 2009 9:25 pm
[quote="Marek"]http://www.thefredcast.com/?p=731
There is an interesting bit on this episode of the Fredcast. I am hearing quite a lot more about very short sharp intervals helping significantly improving performance. There is a bit on this podcast at about 20mins in or so. A bit yankee, but quite interesting.
Cheers
Marek...
Marek,
Here's a study against high intensity for mitochondrial biogenesis :-
" Metabolic Acidosis Reduces Exercise-induced Up-regulation of PGC-Ialpha mRNA."
D. Bishop,J.Edge,T.Mundel, E. Hawk, M.Leikis, H.Pilegaard University of Verona Italy., University of Palmerston North New Zealand,Wellington Hospital New Zealand, University of Copenhagen Denmark.
Purpose :
Recent research has shown that sodium bicarbonate (NaHCO3) supplementation during interval exercise rersults in greater improvement in mitochondiral respiration and endurance performance. It was hypothesised that this may have been due to a negative effect of metabolic acidosis on the up-regulation of genes responsible for aerobic adaptation. A key regulator of mitochondrial biogenesis is peroxisome proliferator activated receptor gamma co-activator (PGC-I) alpha. The purpose of this study was to determine the effects of metabolically-induced acidosis on the exercise mediated mRNA response on PGC-Ialpha mRNA expression.
Methods:
Eight active males performed 10 x 2 min cycle intervals at 80 % VO2 max intensity on two separate occasions ( 2 weeks apart).Participants ingested either ammonium chloride ( acidosis) or calcium carbonate (Placebo ) the day before and on the day of the exercise trial in a randomized, counterbalanced order,using a cross over design. Biopsis were taken from the vastus lateralis muscle before, immediately after exercise and also after 2 and 6 hours recovery. The RNA content of PGC-Ialpha was determind by RT-PCR and normalized to total cDNA content determind by OliGreen.
Result:
Exercise markedly increased PGC-Ialpha mRNA content at 2 and 6 h of recovery in both conditions. However, ACIDOSIS was associated with a supressed response relative to the Placebo condition at 2 and 6 h of recovery ( 2 - 3 fold decrease , respectively. A similar response was also observed for citrate syntase mRNA at 2 h recovery.
Conclusion:
The present data demonstrate that metabolic acidosis reduces exercise enduced up -regulation of PGC -I alpha m RNA, suggesting that metabolic acidosis may interfere with training induced mitochondrial biogenesis."