> >>Interesting article... if you read it further...
> >>
> >>This was a study of "well-trained cyclists" and the
> >>exercise test was
> >>performed at 62%-64% of VO2max. Have you any idea
> >>how low an intensity this
> >>is for a trained athlete?
> >>
>
>Then why did these cyclists reach the failure point in about 150
>minutes?  I'm missing something here.

Your question is a little unclear, but I guess you're asking if the
intensity was so low, why would the athletes be exhuasted after 2.5hrs?

That would be because all endurance exercise relies on glycogen to a certain
extent. Even at low intensities, while fat is the predominant energy source,
glycogen is being utilized. As soon as all glycogen is used, the athlete
will have to stop due to feeling of severe fatigue, even dizzyness and
delerium (commonly known as the knock, bonk, or 'hitting the wall').

With hi-carb junkies, they would have full glycogen stores and their bodies
would be used-to using them up predominantly knowing more glycogen would
replace it later (in the diet). With low-carb (junkies also? :-)), the body
would be more glycogen sparing, would rely on fat more and could make the
small amount of muscle glycogen go further. However, in both cases the
limiting factor is glycogen. As soon as that's gone, the exercise must
cease.

It would be interesting to see if the results differed if the protocol was
reversed. Looking at the study the athletes had 4 weeks of further training
between the first and second test. That could easily account for the
difference. The authors checked VO2max between the two tests, to ensure that
had not changed, but the athletes lactate threshold may have changed with 4
weeks training making sub-maximal exercise less glycogen dependent,
accounting for the 4% difference.

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