Quantifying how hard you’re training with simple measurements, such as heart rate or the traditional constituents of training (mileage, intensity, frequency) will reflect the effort you’re putting into your training but, what it won’t do is assess your actual response to that training.
Just like measuring how much petrol you put into your car won’t tell you exactly how far you can drive before the tank is empty again, (that depends on engine performance, how you drive the car etc), simply knowing that you ran 40 miles in a week can’t really tell you if you’ll end up running a faster marathon.
If only training adaptation was as simple as the equation: training + nutrition + sleep – life stress – every other hassle = adaptation!
If it was that straightforward, then changing one or more of those variables should result in improvements in fitness. But unfortunately it just isn’t that clear-cut and much of the research into genetics and exercise is devoted to understanding what separates the training “responders” from the “non-responders.”
However, the question of how to assess and quantify the effects of training on the body may finally have an easy, and surprisingly accessible answer.
Thanks to recent technological advances, it has now become possible to measure a physiological function called Heart Rate Variability (HRV). And best of all, the means of measuring this metric has broken out of the clinic lab and is now within reach of most people’s pockets.
So what is Heart Rate Variability?
HRV reflects the heart’s automatic regulation. Specifically, it measures the time gap between each heartbeat and is usually assessed while the person is resting. It may appear to us that the gap between each of our heartbeats is always the same, particularly when we’re resting. In fact, it isn’t. Tiny, millisecond differences occur in the length of gap between each heartbeat – and research has linked a high HRV – that’s a greater variation between each heart beat – as a marker of the heart’s ability to adapt, and so a sign of fitness. The converse of this is that a low HRV is linked to fatigue and over-training.
And what does this mean for sportsmen and women?
Well, in practical terms, it means that HRV can be used to determine your response to training in general; and even your response to specific types of training.
In a 2016 study, presented in Medicine and Science in Sports and Exercise, researchers examined the effects of an 8-week HRV guided running programme on running performance. Forty recreational endurance runners were divided into an HRV-guided experimental training group and a traditional, predefined training group (trained according to a predefined training programme that included 2-3 moderate/high intensity training sessions/week). For the experimental HRV group, the timing of higher intensity training was based solely on HRV, measured every morning. If the subject’s HRV was within a normal, acceptable range, higher intensity workouts were programmed. If HRV fell outside that range, then low intensity training was performed instead.
The researchers found that at the end of the 8-week training period, only the HRV–guided training group improved its performance in a 3000m running trial, even though they performed less moderate and high intensity training sessions compared with the predefined training group. The study concluded: “The timing of moderate and high intensity training sessions according to HRV is more optimal compared to subjectively predefined training.” In short, following a training plan out of a book or off of a website may not optimally improve performance.
HRV shows promise in identifying what types of exercise are individually optimal before an exercise programme is started. In another study, published in the Scandinavian Journal of Medicine and Science in Sports in 2015, researchers measured the response of recreational runners to either high volume or high intensity training. By assessing HRV before the training period started, the researchers hoped to better understand how individuals would respond to different intensities and amounts of exercise.
At the end of the 16-week programme, the study indicated that the runners with a higher HRV improved to a greater degree with high-intensity training while those with a lower HRV responded better to a higher training volume rather than training intensity. The researchers concluded that: “HRV may be used to individualise endurance training in recreational endurance runners, especially to adjust training volume and intensity, to achieve greater improvements in endurance performance.”
It seems that HRV may hold the key to telling runners how to train for maximum gain before they start a training programme. Having a high HRV may indicate that you can take a greater dose of high intensity training; whilst a low HRV may be a red flag, or at least a yellow one, warning that long, slow distance training is needed instead of intense practice.
Wouldn’t you like to know the most efficient way to train for your next event?
The lead author of both of the above studies, Dr. Ville Vesterinen of Finland’s Research Institute for Olympic Sports, recommends that between 3 and 4 HRV assessments are carried out each week to achieve a good, overall view of the current training status. Dr Vesterinen states: “Given the large day-to-day variation, it is better to use long-term (e.g. 7-day) trends rather than one single HRV value. It is also essential to standardise the assessment protocol – time of day, length of measurement – to ensure good quality information.”
Measuring heart rate variability used to require complicated cardiac monitoring in a laboratory. Now, all it takes is a small ear-clip sensor, some computer software (to analyse the data) and, of course, a computer!
The StressChecker HRV package, produced by Respilex, a Netherlands-based biotech company, is an inexpensive, easy to use piece of kit, that enable athletes, body builders and other sportsmen and women to add HRV assessment to their training arsenal.
Using HRV undoubtedly helps to take the guesswork out of training, so instead of the hit and miss approach, of trying different programmes to see which one works for you, the information gleaned from measuring your HRV could serve to quickly turn you from a training non-responder to someone showing real gains.
This post is adapted from an original article by Ian McMahan, which first appeared on Competitor.com, published 22nd March 2016