I know I’m not to only data nerd out there, I wear a fitness tracker, log my sleep, track PR’s and my cycle with exacting dedication. Today we’re going to talk about one of the most important pieces of data out there and that is heart rate recovery. Why is it so important, well its a reliable indicator of your relative level of fitness, whether you might be overtraining and it might even predict your own death. Scary right? A while back I wrote about heart rate variability which has some overlaps with this topic but on the whole heart rate recovery after exercise is much better understood. When a runner I know was starting out with some medical issues this is the metric that his doctor was most concerned with. In fact this metric is so well understood that it’s actually the basis of the cardiac stress test. Yes they are looking at the activity of your heartbeat during exercise but also how it recovers after. Let’s take a deeper dive into the science and see how yours and mine compares!
Why do we even care?
So here’s the anatomy and biology of why we care about heart rate recovery. Simply put it’s how much your heart rate drops in the short time after you stop exercising. In biology and medicine we often can’t look directly at what we want to measure because it will kill you and then really what’s the point? Your vagus nerve (there’s actually 2 but we refer to them in the singular because why not?) Is like hella important in the body. It controls so many important thing like the heart, lungs and the digestive system. It provides parasympathetic control to these systems in other words they type of regulation you can’t control with sheer will. In other words if you have good vagus function then you have good control over your heart rate and that indicates things are ticking along as they should be. Since taking the heart out or the nerve to watch it work would kill you we use heart rate recovery as an indication of how your heart is working as a whole.
The thing is in biology we have to check and see if the thing we are measuring is actually a good stand in for what it represents. In other words if you have slow heart rate recovery is that correlated with poor outcomes and is a fast recovery linked strongly to better outcomes.The answer in this case is a definite yes! When we measure heart rate recovery in patients it is a great predictor of how they will do long term (Cole et al., 1999). In fact these results were more directly measured in both athletes and normal volunteers by measuring heart rate recovery with and without administering drugs that block the activity of the Vagal nerve. Heart rate recovery was slowed after the administration of these drugs showing that measuring recovery heart hate is a good stand in for monitoring the activity of this very important nerve. This study also showed that heart rate recovery was faster in athletes than the average population but people with heart failure showed slower recovery than the average population. (Imai et al., 1994). Interesting fact heart rate recovery acts pretty independently of age. No matter how old or young you are it’s a reliable indicator of your overall level of cardiovascular health (Darr et al., 1988).
Can you improve your heart rate recovery?
Great news you totally can and you don’t necessarily need to run a marathon to do it! Too many forms of exercise to list have been studied for their effects of post training heart rate recovery speed and magnitude have been studied. Suffice to say they all work in elite athletes and recreational exercisers alike from both moderate and heavy forms of exercise (Bellenget et al., 2016). Highly trained athletes show dramatic improvements in heart rate recovery after upping their training like triathletes (Thompson et al., 2015) In fact it’s such a meaningful and easy measurement that I think it’s a great idea to track your heart rate recovery as a means of tracking progress if you’re new to working out. Weight and measurements are great but this measurement actually shows you you are in fact getting healthier and will likely live longer!
What if you already have the super scary diagnosis of chronic heart failure are you doomed in this regard? No, not at all, of course work closely with your doctors but a meta study of many studies showed that all groups that took part in different hospital based, supervised exercise programs showed significant improvements in post-training heart hate recovery and several other measures of heart health (Hsu et al., 2015) and (Aubry et al., 2015). I’m not sure how important improving your heart rate recovery is to you if you’re a highly trained athlete on it’s own but it cloud be pretty cool to keep track of during training to show you are actually getting more fit and ready for race day!
Here’s a nifty chart I found to let you know how you stack up plus you know, goals!
What about that whole predicting death thing?
So now that we’ve talked about all the effects training has on your heart rate recovery and why you should care it’s time to address the big fat death elephant in the room. Whether or not you have cardiovascular issues or not your heart rate recovery rate after exercise can predict your imminent demise. Before we get too freaked out about this though I’m not that sort of doctor. I’m the read and interpolate the research type not the treats people so if you have concerns go talk to someone with a perception pad STAT! Also the data we get from out fitness trackers on this sort of thing is pretty dang good but not quite up to par with a stress test in a hospital so don’t freak out. Last of all having a poor recovery rate on a single workout isn’t cause for concern right away. I don’t know about you but when I get home from a run I almost never end my workout and then sit down immediately. Usually I end it partway up the driveway which happens to be a 150m steep hill and then continue walking up it. If you’re concerned with the data you get make it a point to end your workout and then sit for 2 minutes a few times chances are you’ll see a dramatic improvement and then freak out gone! Also other outside factors are known to negatively effect heart rate recovery like caffeine (Busawat et al., 2014).
We talked about the recovery rate after the stress test in cardiac patients and it’s long been known that it’s actually predictive of dying in these patients. In one study roughly 9500 patients underwent treadmill stress tests until their symptoms limited their exertion levels. In the 5 years following the study a little over 300 of those people died. In general if a person’s heart rate fails to go down by 12 beats per minute in the first minute after stopping exercise that was predictive of death in the next 5 years. Of course not everyone had poor values some did rather well even with a cardiac diagnosis. The researchers were able to determine that after controlling for other factors heart rate recovery values were predictive of both death and not-dying for over 8500 of the 9500 patients (Nishime et al., 2000).
Researchers also redid this experiment with healthy populations and the results were repeated many times over. In other words even in healthy populations with no cardiovascular diagnosis researchers found over and over that lower heart rate recovery values after maximal and sub-maximal effort were predictive of death and or an impending cardiac issue. So much so that the researchers recommend that taking this measurement of patients at regular check ups. The only better predictor of death was age. (Qiu et al., 2017).
I think I always knew that heart rate recovery was super important but that might be because my Dad was always having stress tests when I was little. It was really fun to look into the subject more and I really learned a lot. Do you track your heart rate recovery and does it improve as you up your training?
Read what I read!
Aubry et al., 2015. The Development of Functional Overreaching Is Associated with a Faster Heart Rate Recovery in Endurance Athletes. PLOS One.
Bellenget et al., 2016. Monitoring Athletic Training Status Through Autonomic Heart Rate Regulation: A Systematic Review and Meta-Analysis. Journal of Sports Medicine.
Busawat et al., 2014. Caffeine delays autonomic recovery following acute exercise. European Journal of Preventative Cardiology.
Darr et al., 1998. Effects of age and training status on heart rate recovery after peak exercise. American Journal of Heart and Circulatory physiology.
Cole et al., 1999. Heart-rate recovery immediately after exercise as a predictor of mortality, New England Journal of Medicine.
Hsu et al., 2015. Effects of Exercise Training on Autonomic Function in Chronic Heart Failure: Systematic Review. Biomed Research International.
Imai et al., 1994. Vaguely mediated heart rate recovery after exercise is accelerated in athletes but blunted in patients with chronic heart failure. Journal of American Cardiology.
Nishime et al., 2000. Heart Rate Recovery and Treadmill Exercise Score as Predictors of Mortality in Patients Referred for Exercise ECG. Journal of American Medicine.
Qiu et al., 2017. Heart Rate Recovery and Risk of Cardiovascular Events and All-Cause Mortality: A Meta-Analysis of Prospective Cohort Studies. Journal of the American Heart Association.
Thompson et al., 2015. Improved heart rate recovery despite reduced exercise performance following heavy training: A within-subject analysis. Journal of Science and Medicine in Sport.
Sweat Sweetly 