Thursday, 11 August 2011

Acute Responses and Chronic Effects

A number of recommendations in resistance training are made by authors attempting to extrapolate from an acute mechanism or response to infer a chronic training adaptation. In many cases this inference is independent of any corroborating intervention studies manipulating the variables in question to produce said acute response, then utilising a valid measurement of the inferred chronic effect in attempt to either prove or disprove the hypothesis. This situation predominantly lies within the realm of hormonal and molecular regulation of muscle mass.

I made a comment on a post at Drew's blog a while back highlighting this issue:

"Understanding of the acute processes I think is important to direct further research, for example a lot of recent research looks at measures of acute ‘protein synthesis’ in response to different protocols i.e. high vs low volume, occluded training etc. But they draw the assumption that the higher measure of an acute surrogate marker in one arm of the trial compared to another will necessarily translate into a greater chronic hypertrophic response. When we look at the volume example for instance however and consider the empirical data, the training studies, we see that low volume, single set exercise is just as effective as high volume, multiple set exercise in producing strength increases and hypertrophy."
In addition Chris made a post a while back highlighting this "Black Box" approach to physiology.

The thing is that for a hypothesis to be plausible it requires both a biological plausibility, that is an acute process (and chronic) by which the variable exerts it's hypothesised effect, and empirical data from intervention studies demonstrating it as a chronic adaptation.

In light of this I was pleased to see this concept discussed by Dr Ralph Carpinelli recently with reference to large muscle mass exercise producing a greater acute testosterone response. It seems that although this is an acute occurrence, it does not translate into an enhanced response in hypertrophy or strength.

Here is a link to the full paper.

http://www.medicinasportiva.pl/new/pliki/ms_2011_01_07_Carpinelli.pdf

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