Why the insane Heart Rate suddenly?

In the last couple of weeks I've found that my heart rate has gone absolutely sky high in the first 10 minutes of a 5km run. I mean, really sky high. I'll start jogging and will feel absolutely fine and  breathing no harder than if I were sat on the sofa, but my HR has hit 170+ BPM, the kind of rate that should mean I'm sprinting, squat-jumping, or absolutely hammering it up a hill on my bike.

This is not normal. At Frimley Lodge parkrun last weekend I hit 190 BPM which is utterly insane given my peak HR is considered to be 192 BPM - I should be at near-maximum output to warrant that, not jogging along looking in alarm at my watch!

Saturday 1st December, Frimley Lodge parkrun

After 10 minutes it drifts down a bit, but is still very high. For jogging round a parkrun in 28 minutes I'd expect to be 125-135 BPM for most of the time.

Initially I suspected this was as a result of the Bulletproof Coffee I'd been having for breakfast - however there is another occurrence, this time in the evening. On Thursday I went for a run when I got home from work, unusually I hadn't cycle commuted so started the run from cold.

A 5km run after work on my local route

Similarly, I set off very slowly and suffered a huge spike in heart rate before it settled somewhat. Still higher than I would normally expect but closer.

This morning Mrs and I took a drive to Brighton & Hove parkrun. I had decided to warmup slowly, and then run at whatever pace was required to keep my heart rate in HR Zone 1, under 152 BPM. During the warmup I walked briskly with a heart rate of around 100 BPM as expected, but as soon as I took the first few slow jogging steps it rocket straight up to over 170 BPM, literally (and I mean literally) within 5-10 seconds. I've never seen anything like it. I stopped jogging after a few steps, and it came down just as quickly. I carried on in this fashion for 15 minutes, gradually able to jog very slowly for slightly longer each time.

Warmup, featuring ridiculous heart rate responses

For the run I decided there was no way I could stay in Zone 1, I'd have to walk round the course! Instead I set off very very slowly, and held a pace keeping my heart rate under observation.

Brighton & Hove parkrun

So it did come down, eventually! A big step down after 10 minutes, before finally getting more normal after 20 minutes or so. Note that my speed was relatively constant throughout this variation. Is it all due to not warming up slowly enough?

After a very slow first km my pace was relatively constant

There's an interesting data point from earlier this week. I went for a 5km on my local route earlier in the week, but this time I had cycled home first. My commute home starts in the West End of London, and is therefore very slow for the first 15 minutes, and not much better after that being punctuated as it is by hundreds of sets of traffic lights.

This heart rate plot looks totally normal for a cycle commute, well within HR Zone 1 (under 152 BPM)

I took this as a brick session, meaning I got in, got changed as fast as I could, and ran out immediately. I was still thoroughly warmed up form the bike ride. I wanted to blow out some cobwebs, so this run was harder than many recent runs, and I completed the 5km in a little over 24 minutes. Still a couple of minutes outside my personal best, but fast enough to have to work hard - the upward drifting heart rate during the run validates that I was certainly working hard to maintain pace.

A faster 5km brick run on my local route

This shows that following a 45 minute low to medium intensity bike ride I don't experience the same spike. This graph is exactly how a hard 5km run always used to look, and just what I'd expect to see. No starting spike whatsoever.

So it looks like there are a few options:

1. Warm up really very very slowly (so slow I can barely even jog!)
2. Warm up with a bike ride every time I run (potentially impractical), or find some other way to warm up (drills? some squat jumps?)
3. Warm up with a 15 minute jog ahead of the start of a run and just let any spike happen and pass - or if there's no time to warm up just accept that I have a huge heart rate spike at the outset of a run and jog through it, saving any harder effort for after 8-10 minutes

Maybe this is a side effect of a low carbohydrate and high fat diet? Why is it happening? My suspicion is that as my metabolism and fuelling has changed, there's some trigger which is not yet attuned to this physiological state.

My body goes "Right, get ready to exercise!" and everything plays according to the rules apart from my cardio-vascular system which for some reason thinks it needs to get a record amount of oxygen to my muscles, or the signal to say that it was already delivering enough is suppressed (fat metabolism takes more oxygen, but I wouldn't have thought that alone explains this).

So, why the insane heart rate suddenly?

Diary of a wanna-be fat burner: Days 5-7

Day 5: Wednesday 14th November

A little harder to get going this morning as I was fast asleep when my alarm went off. Soon perked up though, with a portion of lovely Bulletproof Coffee and the surprise of being a whole kilogram lighter than yesterday. It's impossible to lose weight from fat at this rate, indeed the maximum advised rate is about 1kg (2.2lb) per week, so clearly I was releasing some retained fluid or have further depleted my glycogen store. My full glycogen stores will weigh around 1kg (varies according to weight and other factors), but there's water you lose at the same time.

If you adopt the Atkins diet which is similar in profile to what I'm doing, rapid weight loss during the adaptation phase is one known effect. This invariable leads to cries from the dieter of "Yay! It's working! I lost 10lb in 2 weeks on the Atkins diet!" - in fact as shown on their website that's one of the primary selling points.

This rate of loss is, of course, unsustainable. You only have a certain amount of glycogen and fluid to lose (though there will be some fat loss too during this period), and once that's gone the diet "fails" (rate of loss becomes comes much reduced) and the yo-yo dieter goes back to their normal dietary habits, and "piles the weight back on" (restocks glycogen, fluids, and probably some fat too). They haven't waited long enough to properly adapt.

I'm not aiming for rapid weight loss, I want some amount of controlled loss but the priority is metabolic change. I feel It's important for me to maintain a strong and regular exercise ethic during this process. I'm trying not to be in a high calorie deficit during this phase (though I am taking in fewer calories than I have been in recent weeks).

Bulletproof Coffee

I was very hungry this morning - but it's hard to tell if it's genuine. I had a yoghurt snack at 09:30, and bacon and egg with some cherry tomatoes at 10:45. Quite different to yesterday where I wasn't at all hungry until lunch time.

In the evening, we had our first attempt at having a meal out, going to one of our favourite local places, the Light House in Wimbledon. It is possible, but some self control, and careful choosing of menu items is required.

 

Pork Belly with crackling, hold the mash, add broccoli and spinach side dish

If your starter comes with toast, like my chicken liver pâté did, hide it in the bread (which you, of course, aren't eating).

Toast in the bread, obviously

....and even with all this yum, I came in at only 32.1g carbohydrate for the day. And we had wine. And I had a Gin and Tonic.


Day 6: Thursday 15th November

Weirdest. Hangover. Ever. Awoke with a banging headache and expected a day of sluggishness and a feeling of guilt for not being able to focus on my work tasks properly (standard hangover modus operandi)  - but the headache cleared in minutes after I got up and downed a bulletproof coffee. I did feel a bit tired (probably as a result of poor quality sleep), but not energy-crashingly so like I would expect to be. I ate on-plan through the day and didn't experience the usual hangover carb-cravings in the slightest (I need toast! And a bacon and egg roll! And a lardy lunch! And a Snickers!).

I was scheduled for a long and serious meeting in the afternoon. Conventionally, this is where I'd have had a big slump and really struggled to stay attentive, the 1pm to 3pm danger zone (probably as a result of a massive slump following an insulin spike resulting from a carb-laden lunch) - but this simply didn't happen. I felt alert and focussed the whole way through - I have done for the whole day, in fact. I fully approve of this experience!

In the evening I had a run scheduled - "Run until it hurts" the Doctor said (more on my knee later). First time running on this plan and only my third run in a fortnight so I was a bit creaky but felt pretty good. I wasn't going very fast, just under 25 minutes for 5km, but my energy levels seemed to be normal. I'm starting to feel a bit weird, like I'm hardly eating any carbs, but I'm not getting tired or being unable to do physical things - where is this energy coming from? Am I metabolising fat already? I did feel a little weak towards the end but that might be as a result of my knee starting to hurt. I'm looking forward to an experimental long run at some point soon.


Day 7: Friday 16th November

My weight continues to evaporate - I was 81.8kg this morning (actually 81.75kg but I always round up), much closer to the "around 80kg" that I'd be happy with. As previously explained, this isn't a weight-loss initiative, but it's a perfectly acceptable side effect! When I started day 1 last Saturday I weighed in at 84.3kg.

I've been feeling more and more alert as the week has progressed. I'm finding it hard to believe that i'm getting through almost the entire morning, including a cycle commute of a reasonable intensity (mid-to upper HR zone 1), with nothing other than a cup of coffee (all be it a 376 calorie one with 41.2g of fat in it).

I'm starting to wonder if my dropping ability to really focus and make good progress on things at work in recent months was as a result of diet? Could it be that simple? I had got well into the habit of having two breakfasts in the morning. This was as a result of a normally fairly heavy morning training load, but as the training load dropped off at the end of the season my breakfasts didn't - quite the opposite. Recently I'd been having peanut butter in porridge in the morning, and then cereal and a banana when I got in - even on the days when I got the tube in. That's clearly excessive.

A genuine typical first few hours of the day - this was October 22nd

By 10:30 I'd consumed 719 calories including 100.8g of carbohydrate.

I'm continuing to feel more alert, more mentally agile, and more focussed and constructive. How much of this is genuine versus psychosomatic? I'm thinking a large percentage is for real. I hadn't read or heard anywhere about a change of mental state and therefore wasn't looking for it.

Mrs mentioned this evening that she'd seen a few articles about the effect of a high fat/low carbohydrate diet on the brain, so I'm definitely going to take a look at that - I'll let you know what I find!