Why Assess the ANS?

I just finished watching a presentation by Andy O’Brien entitled “Modern Concepts in Program Design – A Systematic Approach to Individualization”. Andy O’Brien works with elite athletes including NHL star Syndey Crosby. His presentation is 28 minutes long and is truly worth watching if you work with athletes. After listening to his talk, you’ll understand why he works with such high level athletes. I’d also like to add that this is yet another great free resource put out by John Berardi and his team at PN. I have no problem endorsing a company that continually puts out top notch information for free. The thoughts in this post are inspired from the ideas and concepts discussed by Andy O’Brien.

In his presentation, Coach O’Brien essentially views program design as problem solving. Naturally, the first step in designing a program is assessing the athlete. An assessment allows us to form a needs analysis and determine limiting factors that impede progression.

An example was provided of a weight loss client who wanted to lose X amount of fat in time for a wedding. After the trainer decided that diet was not the limiting factor, emphasis was placed on increasing calorie expenditure. What would appear to be a very effective program for improving body composition was prescribed (resistance training, aerobic and anaerobic conditioning, plus a thermogenic supplement). The results however were quite surprising. The client in fact gained fat after several weeks. The reason? Incorrect identification of the limiting factor.

It turns out that the client had a significant ANS imbalance of sympathetic predominance. Even before the exercise program, the nature of her work and lifestyle was highly stressful. Adding intense exercise 5 days/week only further increased this imbalance resulting in unfavorable hormonal responses and poor adaptation to the program.

O’Brien mentions a related study by Messina et al. (2012) entitled “Enhanced parasympathetic activity of sportive women is paradoxically associated to enhanced resting energy expenditure”. Unfortunately I do not have access to this text at the moment but here is an excerpt from the abstract; “These findings demonstrate that resting energy expenditure is higher in the athletes than in sedentary women, despite the augmented parasympathetic activity that is usually related to lower energy expenditure.”

This is one example of why it is important to assess the ANS. I think there are many folks who reject HRV as a useful metric in monitoring athletes or individuals. Perhaps this is because there is a misunderstanding of what the data is telling us or perhaps because interpretation of the data is difficult. Maybe it’s a compliance issue. Regardless, in my opinion, an objective measure of ANS status requires at the very least, periodic assessment for several reasons.

We measure strength, power, body comp, etc. yet ignore one major component of the body that largely acts as a moderator in training response and adaptation. HRV is likely the cheapest and most efficient non-invasive tool we can use to acquire ANS information.

To be clear, I’m not saying that HRV is first in the hierarchy of assessment (if one exists). I’m merely saying that the ANS plays a huge role in our health and performance and requires monitoring and assessing just as much as performance and body composition. How can we rule it out as a limiting factor if we don’t consider it at all?