Recovery and technology

08/09/23 22:44 Filed in: Riding

For anyone racing their bike 50 years ago, about the only means available for measuring recovery would have been a finger to the neck feeling a pulse while looking at the second hand on a watch counting time – all before getting out of bed. A low(ish) HR suggested things were going OK. A high(ish) HR suggested that perhaps an easy day was in order. Not definitive. Frequently stuffed up by getting out of bed before remembering to measure HR. For the dedicated only.
Then Polar introduced a portable heart rate monitor. Suddenly it was possible to monitor on and off bike heart rates without paying attention. They were very expensive at first, and not terribly robust. But they opened up sports science a lot. By the time I came into cycling, the Polar patent was about to expire and the range of Polar watches was extensive. Prices were way better than they had been years earlier.
Incidentally, when the patent did expire and the market was flooded with copycat technology, all of the models that I saw were basically rubbish. Polar still had the upper hand. The end of Polar as market leader and trend setter roughly equates to the time they first moved production out of Finland.
There was a very high-end Polar that did a morning heart rate test. It required as much dedication and memory as the above-mentioned finger test – it had to be done before you got out of bed (and my athletes forgot as much as they remembered). Slip on the chest strap, get the watch into the correct mode, start recording, lie still for 1 minute, stand and repeat the 1 min. Repeat for 30 days and only then the watch could tell you how tired it thought you were. It worked, but the human weak link made it less successful than I’d hoped.
With a power meter one can calculate TSS – the training stress score. This metric allows characterisation of all rides to a standardised scale. How does an afternoon of sprint training at the velodrome (TSS=80) compare to a leisurely longer ride (TSS=80)? Answer in this example is that they are identical in physiological impact. With TSS the training plan can be measured and recovery allowed for – but only in a predicted sort of way, not in an actual way. By this I mean that, on average, this athlete will be fine with this load so we can keep going. But what if they’re not?
Now most wrist devices can measure heart rate variability as part of their regular routine. A built-in optical heart rate monitor not only measures HR with great accuracy, but it can pick up on the interval between the two peaks in a normal heart rhythm. This interval changes depending on the demands of the sympathetic and parasympathetic nervous systems. Routine monitoring of this gap allows it to be characterised as HRV – heart rate variability. The value is suppressed in tired (unrecovered) persons. It is also low if one is overly rested and lethargic.
Unlike the prior analyses, HRV doesn’t require one to do anything – just wear the watch and check in with the results now and again. And it is accurate right now because it is based on real measurements of fatigue. Done a hard week and handling the load; HRV will remain steady. Done a recovery week and got sick but symptoms haven’t appeared yet; HRV will be depressed.
With HRV you should be able to measure how long is long enough for your personal sleep needs. It’s a cool insight into how the body works, and it is an accurate reflection of how you’re tracking.

Some further notes on HRV
HRV can be measured continuously by a wrist device. That's not sensible because every activity will impact on it in a way that doesn't help interpretation of the value. It should be taken just prior to waking every day. I think - not 100% sure here - that you can set some Garmin's to measure only during sleep. That's better than all the time. The really useful measurement is just at the end of sleep.
I have been comparing the figure that different people get and it is highly variable. In a paper on HRV I saw a range listed from high 20s to over 100. In my own exploration of individual's values, I've seen mid-40s and low-100s. The point of this is that all that really matters is the consistency of your own score. At least to some extent. If you make a lifestyle change and the value increases, that is a positive change in your life.
HRV is really a miniature version of the variation in HR seen across different activities. For example at rest a pro cyclist might have HR of 40. In the middle of the bunch it might increase to 100. And climbing a 17% gradient in a break-away might push it up to 200. So too does HRV respond to the demands of the body. Inhalation and exhalation change the delays in the system. Digestion. Healing. Immune system working hard with an infection. All of these boost or suppress one side of the sympathetic : parasympathetic balance.

Michael Hanslip Coaching

If you want to go faster, you have to pedal harder

Recovery and technology