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December Research Round-Up: the HRV Edition


  • Joakim says:


    How come there was an increase in parasympathetic dominance in the functionally overreaching athletes? Isn’t overtraining rather associated with a suppression of the parasympathetic nervous system?

    Or was it rather that they didn’t find any signs of overtraining in the functionally overreaching athletes?

    • Bret says:

      I had to look into this too as I thought that overreaching led to sympathetic dominance but that’s not the case.

      • John says:

        Functional overreaching can “scatter” HRV. In general a sympathetic predominance would characterise the functionally overreached but like literature on other indices of overtraining/overreaching the relationship isn’t black and white. Read Plews et al. 2013.

      • Joakim says:

        Thanx for the answer, and looking forward to the next issue of the S&CRR

  • The key is that HRV changes can be used, but as the study showing a shift towards parasymp when overreached –you need to look at the group too if they are endurance based (as was studied above) or strength based.

    In general, for most strength based athletes you tend to become more sympathetic dominant, but you can shift quite rapidly to massive parasymp if you push it too far for too long. I think of it as your body’s way of surviving–it will “shut you down” so that you won’t do much of anything. I’ve seen athletes who are massively parasymp and feel horrible, hormones crashed and are probably over trained (OTS).. Once you get to that point, it takes a long time to come back.

    This is also why you need to compare HRV to performance and other markers and not just pluck 1 number off. As the other study showed, comparing it to the athlete’s baseline is the best way to go. I personally have them run a 4 week baseline before I do anythng with the HRV number.

    For the clients I train, I find the overall baseline to be the best indicator and which direction it is going. If it is tanking (becoming more symp driven), I will have them back off or change up their training to –gasp—ore easy aerobic driven for a few sessions with low to moderate heart rates. Ideally those sessions would also be semi fasted (no pretraining carbs).

    Thanks for the great info!
    Mike T Nelson

  • Rich says:

    Nice post!

    Any thoughts on non-training stressors and HRV? Could HRV be used to predict or prevent illness and if one is sick, does it show up on HRV scores?

  • Rich,
    I have seen that HRV is normally quite good for that actually When I’ve been sick over the past 3 years, my HRV just tanked. I’ve seen that in clients too. There is some data to support it too and we know there is a connection between OTS and the immune system
    Mouse study

    Mike T Nelson

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