The effect of heart rate on shooting - Part 1

Quite a long time ago now, I noticed that the beating of my heart appeared to slow when I was in the aim. I remarked as such to a medically-qualified friend, who replied that he was not in the least surprised as it is known that it is possible to consciously slow heart rate*. Having recently bought myself a Garmin 225 GPS watch combined with a heart rate monitor as a training aid for running, I decided that it would be interesting to see what results I got when measuring my heart rate during a SCATT session.

The Effect of Heartbeats on Aim
It's logical that heart rate (and possibly strength of heartbeat) will have an effect on aim. The hydrostatic pressure of the surge of blood around the body will disturb the fine aiming required to shoot a rifle accurately, either as it passes through the organs of the body or through the major blood vessels of the upper limb**. Indeed, the disturbance caused by heartbeats can be observed using a SCATT as is shown in the diagram below.

Fig 1.0 - The effect of heartbeats on SCATT traces. The notation indicates the heartbeat number in sequence and the time before the shot broke.

What is perhaps less logical, or at least less well known, is that it is possible to consciously control heart rate to some degree. By extending this, maybe it's possible that some people can subconsciously control their heart rate under circumstances or, to put another way, do I subconsciously decrease my heart rate while shooting?

The Measurement of Heart Rate
I bought my watch primarily for running, as my pace judgement isn't great and this is critically-important when running long distances. Go out 15 seconds per mile too fast in a marathon and the last 10k is likely to be deeply unpleasant, not to mention very slow. The watch that I bought also has an integrated heart monitor, which works by detecting colour changes under the skin of your wrist when bloodflow increases. Once an activity is recorded, the data can be viewed through the Garmin website or through a 3rd party app like Strava. The plan is simple, start the heart rate monitor and then correlate the heart rate output with shots from SCATT.

Fig 1.1 - Strava output for my last 5k parkrun. The red line is heart rate.

Experimental Conditions
I fired a good 10 shot group using my SCATT wearing the heart monitor. I was careful to try and do this as close to normally as I was able using my normal kit and technique. I switched on the heart rate monitor after warming up, but before I got down to shoot.

Fig 1.2 - SCATT results.

Heart rate monitor results
The heart rate trace yielded some great results and demonstrated exactly the effect I wanted to observe; however it also yielded something rather unexpected. Given that my resting heart rate is somewhere around 50bpm*** I was expecting to see my heart rate decrease to around that level or possibly lower while in the aim, and it to increase moderately when back out of the aim to, say 90bpm. The raw graph looks not dissimilar to this expectation.

Fig 1.3 - Heart rate results. Note the average heart rate of 90bpm.

When I superimposed the shots on the graph, as is shown below and then actually looked at the specific heart rate numbers I was rather surprised to see that the average during shots was 60-65bpm and between shots it went as high as 130-135bpm,which is approximately the same as when I run at a 9 minute mile pace on a flat course.

Preliminary conclusions
It is clear from the result that I am subconsciously controlling my heartbeat when doing SCATT sessions; however the range of heart rates was much broader than was expected. In the next article, I'll have a crack at explaining what might account for this variation and whether there's any way of using it to our advantage.

* Vid. http://www.ncbi.nlm.nih.gov/pubmed/22744827
** It is worth noting at this point that at least two aspects of shooting technique are aimed at diminishing the effect of heartbeats on aim: The modified Estonian position is supposed to reduce the effect of bloodflow through your guts on aim, and correct positioning of the sling on the upper arm reduces disturbance from the brachial artery.
** Average for a 40 year-old man is something like 70bpm according to http://www.topendsports.com/testing/heart-rate-resting-chart.htm but I've been running for few years now, which has had a significant effect.

In sickness and in health?

I am pretty rarely ill. Aside from a couple of broken bones (right medial malleolus in a rock climbing accident and an RDI fracture of the left distal radius) and appendicitis as an eight year-old, I'm rarely out and out ill. I average one day off work every other year, give or take. As a result, I hate being ill and feel guilty about it when it does happen, particularly if I have to take time of work or training.

I'm currently ill with man 'flu and I hate it. I've been ill enough to have a sore throat, headaches and general cold-like symptoms but not so ill that I feel justified in taking time off work. So I'm left wondering what to do about training.

The question really asking here is; when should you say "to hell with it all, I am going to take time off  training"?

And the answer we're really going to get is "it depends".

In my case, I've laid off the phys and the cardio for most of this week; although I've possibly taken the cardio a teensy bit far in recent months, so laying off this is no bad thing anyway, even if just to give my legs' connective tissues a rest from being beaten into the pavement for 50+ miles each week. But this is all really a sideshow, what I would like to work out is when to take time off the important thing, the real deal; when to take time off shooting.

It's always going to be a judgement call: the training you have planned, the illness, the weather conditions, the distance to the nearest bathroom (really important in some cases). Yes, all are relevant factors but that said, to my mind they are all subservient to one thing; do you feel like going shooting? I think that I've already set out to address questions motivation and how the quality of training is just as important as the volume of training, so this is fundamental. In other words, if you don't want to go train or shoot and you don't think that you'll warm to the idea as you get into it, then don't waste your time. You'll probably just end up going through the motions and not putting quality time in, which is possibly worse than not putting time in at all.

Today, I'm taking the day off with man 'flu. Despite the offer of a day's shooting at 1,000 yards in autumn sunshine out on the East coast I'm lying in bed typing this having had a wonderful lie-in and not one, but two breakfasts in bed. I don't feel guilty in the slightest.

Bugger.

Decided to record my heart rate using my Garmin 225 watch during this evening's SCATT session as part of an experiment but must have accidentally deleted the session. Bugger. Will try again tomorrow.