rojeee

Nick should leave London and go live in the countryside - that’s the only place where traditional British values are alive and well.

Nitpick but Alex Yee won gold in 2024, Blummenfelt was 12th!

I'm working on a running app. Mainly for me but others have expressed interest.

It's a performance analytics platform for runners who love to dive into the details after they've been for a run and to be able to accurately track their progress over time.

It's not like Strava because I'm not including any social elements, intitally. And not like trainingpeaks because it's focused on individuals as opposed to teams or coaches. Also the analytics and models I offer are peronalised as opposed to one-size-fits-all. It's also running only. No cycling or anything else.

Ideal target market would be fairly decent amateur runners (e.g. sub 3 hour marathoners) who already know quite a bit about training but don't have a coach and are not good enough to be pro and have a full team doing this stuff for them. The pros have awesome tools but sadly most are not available for us mere mortals BUT I can build some of them! Example features:

1. Personalised "adjusted speed" models. The strava GAP model doesn't fit very well for me and many others, so I've made my own personalised model which gets updated each week. If you get better/worse at running up hills then model adjustments take that into account. The idea is not to provide a physiological correct model but more a performance based one.

2. I'm trying to do the same for surface types, heat and humidity as well. Of course these models are not personalised. I'll get to wind later on as it's much more complicated than the former. The idea is to have an accurate representation of "effort pace", which you can use as an input to performance models.

3. Using adjused pace data I will offer a pace/duration model to estimate critical speed/LT1/LT2/VO2max and this model forms the basis of tracking progress over time. Clearly most training wont be all out efforts, so I also estimate race performances based upon current fitness as well. E.g. if you ran X speed for Y time at a sub maximal effort then you can estimate what a maximal effort would be based upon the remaining aerobic and anaerobic power. From reading sports science literure, this is the most advanced way to track performance at the moment. The actual model I use is called an omniduration model.

4. I also have build some other models, e.g. Daniels running formula, which can be used but I don't find them to be as useful as the omniduration model.

5. I'm also trying to model how a workout or training session will effect your fitness. Where it's base/aerobic, threshold, VO2max or an anaerobic effect. Then, the idea would be to look at future training performance to assess whether the model was correct. You can then assess which types of training you respnd best to as well as which types of sessions you need to get the performance gains you need for your next race.

6. Specific race time predictor. Most platforms offer a single figure prediction for a distance but I want to offer specific race perdictions which take the course and weather into account. The model will give you splits taking all this into account.

7. Cohort adjusted performance models. How are you tracking against people your age? But more importantly, how are you tracking against people doing a similar volume and type of training to you? Are you improving at a similar rate?

There's a tonne of other stuff I can add but I'm going to keep it simple and focus on performance modelling for now because no-one seems to offer any decent tools around this at the moment.

If anyone found this interesting then I'd love to hear any feedback - let me know. Cheers!

"it never gets easier, you just get faster", or so the saying goes

Sure. It's a binary file and there is a spec for it on the garmin website. There's lots of libraries available for most popular languages for decoding and encoding. You can download an app for your computer. I believe it's called Garmin Express, which allows you to sync fit files to your machine.

I'm building a running analytics app, which is really just for myself but if it turns out to be any good then I'll might turn it into a SaaS. Target market would be for fairly decent amateur runners (e.g. 2:20-2:30 marathon) but not good enough to be pro. The pros have awesome tools but sadly most are not available for us mere mortals but I can build some of them! Example features:

1. The strava GAP model doesn't fit very well for me. So I've made my own. I update the model each month too.

2. I've also built a wind resistance model which works quite well. I'm trying to do the same for surface types, heat and humidity as well.

3.Using adjused pace data I built a pace/duration model to estimate critical speed and this model forms the basis of tracking progress over time. Clearly most training wont be all out efforts, so I also estimate race performances based upon current fitness as well. E.g. if you ran X speed for Y time at a sub maximal effort then you can estimate what a maximal effort would be based upon the remaining aerobic and anaerobic power. From reading sports science literure, this is the most advanced way to track performance at the moment. The actual model I use is called an omniduration model [1].

4. I also have build some other models, e.g. Daniels running formula, which can be used but I don't find them to be as useful as the omniduration model.

5. I'm also trying to model how a workout will effect your fitness. Where it's base/aerobic, threshold, VO2max or an anaerobic effect. Then, the idea would be to look at future training performance to assess whether the model was correct. This was you might be able to determine which types of sessions result in the best outcomes for you.

[1] https://pubmed.ncbi.nlm.nih.gov/32131692/

Yup, I have a Garmin Fenix 8 AMOLED. It's an excellent watch. I run for 6-8 hours a week and I only need to charge it once a week. It is very hard wearing and has so many capabilities I don't know where to start. It even has a flashlight with red LED for during the night. With Garmin connect down I can just grab the FIT file from the watch and upload to Strava manually or perform my own analysis locally.

Well.. a crude estimate of relative running economy is pace/heart rate and tracking it over time. Seeing the number go upwards means your economy is increasing and vice versa.

A fair amount of people track this because it's a feature of pretty much every training/coaching app.

Simply because I find it gets me much better results. I know that to run a 15 minute 5km I need to be able to run that pace in training. I don't really care what my lactate threshold or VO2max is other than it's just interesting to know. I use a critical speed (pace/duration) model to know what paces are metabolically steady state and which are not. So based upon how I perform in training, I know pretty much what paces should be within the realms of possibility for a maximal effort and I use that to guide my training.

edit: I'll just add that I do use physiology to guide the training paces. But when you've been training for a while you know that 1) Marathon pace is aerobic threshold pace. 2) Half maraton is lactate threshold pace. 3) 5km is critical speed. 4) 10km is between critical speed and lactate threshold. So whilst I do use physiology to guide trianing paces I don't use a zone system or anything like that. I just design workouts which I know touch on the various systems I need to improve.

I think you are right regarding lactate threshold but im not sure how they factor in running economy as it's difficult to calculate. You need an accurate VO2 measurement. I guess they use HR as a proxy but in practise I find HR isn't such a good measure of metabolic output for various reasons; hills, unrelated stressors, heat, aerobic decoupling, etc.

Good question. Haven't done a cooper test but from my pace duration curve I'd be looking at a touch over 4km for 12 minutes. The calculator I used online said my VO2max would be 78, which can't be right. I'm one of those athletes with good running economy and a high lactate threshold but comparitvely lower VO2max. I've always been worse than sprinting and at shorter distances than my peers but I find longer distances easier.

I'm sorry I can't find the paper which discusses VO2max and how it could potentially fall with lots of low aerobic training e.g. aerobic threshold running. The idea of the paper was to show that training to improve physiological markers like VO2max didn't necessarily translate to better race performance and infact sometimes training to improve the marker actually decreased it... One of the things they noticed was that certain marathon runners actually had a fall in VO2max but ended up with faster race times, illustrating that race performance is determined by factors other than VO2max.

Annoying, if I find it, I'll reply to your comment with the link. It's just one paper though, probably something in it but it's definitely not the consensus view of exercise physiologists.

Yeah only for 5km though. I can't run a marathon at that pace!

Apologies, my wife is not keen on me sharing Strava profile on the web as people can basically see where we live (UK countryside and we are the only house in the area!).

Low 15:00s. I doubt I'll be able to break 15 though as I'm just getting too old now. I used to train seriously when I was a teenager so maybe those adaptations stick with you as you get older.

It's a good question. I find that the most important thing is running at or close to race pace. I follow Canova's training philosophy quite closely. Definitely recommend reading the runningwritings link I posted above.

I do between 80km to 100km a week.

Most of my running is done at a moderate pace. I just do this to get mileage in. Most of it is quite hilly. Looking at about 300-400m elevation for each 10km and runs range from 10km to 20km. Pace is around 4:00/km to 4:20/km.

If I do a workout, I follow it with a recovery run. Pace around 4:40/km. If a super hard workout then I do two days of recovery runs.

I never run doubles because I have young kids and don't have the time.

The most important ingredients are the workouts. I never repeat the same workout. A typical one for 5km training would be: a few km warm up, then 3km @ 97% 5km pace, 2 min moderate, 2km @ 5km pace, 2min moderate, 1km @ 103% 5km pace, then a recovery pace warm down. About 15km in total. That's a hard workout and would be followed with easy running the next day. I would do that workout to improve lactate buffering and improve anearobic capacity.

For lactate threshold I'd do something like 20x400m at LT pace with walking rest for 3 minmutes inbetween. This is where I might use the hyperbolic model to figure out when all the metabolic byproducts are flushed out so you can basically do the next 400m mostly recovered.

Other workouts might be aerobic thresohld runs. So marathon pace running for 15km to 30km. These are the long fast runs that canova talks about. They are hard and you need a lot of recovery after. I really find they improve performance quite alot. They are not presecribed in most training plans and I feel they are a key missing ingredient.

I do a fair bit of hill reps and sprints as well. They are probably best for improving VO2max. Lots of rest inbetween reps, you need to be fully recoved for the next one to get the benefit.

Lastly, you need to keeo touching on all the various metabolic systems. If you don't use it, you lose it. Keep your training varied. Sprints, short interbvals, long intervals, long fast runs, hill reps, ladders, alternates, with varying levels of recovery and at different speeds. Make sure your training is additive. Don't remove any class of session, just add more different types.

Do strength/core workouts. Plyometrics. You need to be strong to bash out miles at MP and not get injured.

I use theragun after any hard workout. Helps recovery loads.

Eat. Alot. On hard workout/long run days I do about 5000kcal.

Most importantly, I think, don't listen to any of the 80/20 polarised nonsense, MAF method, or anything like that. One size fits all training regimes don't work very well because everyone is different. They work for beginners because _any_ running will have them improve.

For more experienced athletes, to run fast you need to practise running fast at the paces you will race at. So doing a training plan which prescribes 80% of easy running as a rule is no good. You only run easy if you need to recover. Every other workout/session needs to target some metabolic system to promote adaptinos which help you run faster. It's the workouts which really make a difference to your race performance.

That makes sense. If you do longer runs (and long fast runs) then your half/marathon time will be more accurate. In general, the issue with using VO2max to priduct race performance is that it doesn't take into account account running economy which is a massive factor in determining performance for longer distances. Same with lactate threshold, which has a big impact on all distances. E.g. at what point do you go from a metabolic steady state to an unsustainable state. It's the most important factor in distance running in my opinion. The threshold can be at quite a slow pace even for someone with a high VO2max if they are not doing the right training. E.g. think of someone who is excellent at HIIT and has a VO2max of 60+ but can't run a fast 10km.

In my experience the only way to get an accurate VO2max is to do a lab test. I'm 40. My Garmin Fenix 8 suggests my VO2max is 69 at the moment but it's actually 64 as I recently did a lab test. Other things to consider: 1) VO2max changes day to day depending how recovered you are. 2) Environmental conditions will also change the value e.g. too hot/cold. 3) You need to be running on completely flat ground to get a decent result as although some of the estimation algorithms take elevation and surface into account, I'm sceptical as to their efficacy.

Ultimately, VO2max, whilst a good health indicator, it's not the be all and end all for running performance. VO2max doesn't take into account lactate threshold and running economy. Two athletes can have the same VO2max but quite different race results for common distances. One might have a very large aerobic capacity but very poor running economy, so metabolically, they require more effort to run at the same pace as someone with a lower VO2max. Also, as you get aerobically fitter, for running long distances, it has been observed that VO2max falls. Need to dig out the reference for this. Like anything, there's lots of nuance.

Some people mentioned race time predictions from VO2max. If you are into running you are better off using recent interval performances to predict race times and measure your fitness. You can use the hyperbolic critical speed model (Similar to FTP). It's only accurate for durations from a minute or so to 20 minutes. Other models can be used to fill in the gaps. This paper explains it [1]

I'm a big advocate of not getting too caught up in physiology when it comes to running. What really matters is "how fast can you run for race distances" and you can improve that by doing more running at or near race speed. E.g. for 5k, do intervals at 105% 5k race pace and longer runs at 95% 5k race pace. This is the essence of Renato Canova's percentage based training [2] which has been very effective for Kenyan Elite's and also myself!

I'm currently building out a training platform which uses the omni domain speed model (see below) as the basis for prescribing training paces and workouts. I'm currently using the system for myself to great effect. Managed to get my 5km race time from around 20 minutes to 15 minutes in under 2 years (and im 40).

[1] "Development and field validation of an omni- domain power-duration model, Michael J. Puchowicz, Jonathan Baker & David C. Clarke"

[2] https://runningwritings.com/2023/06/canova-marathon-book.htm...

Yes, sorry, you are right to point that out. I meant 30 mins!

My point is that if the capability of your aerobic system is very poor - and it is for the vast majority of people, including many HIIT advocates - then whatever exercise you do, you'll very quickly be approaching anearobic territory and find it very difficult to stay at a metabolic steady state for long durations of exercise. When I mean anaerobic, I don't mean "zone 5". I just mean that there will be a much higher percentage of anaerobic glycolysis happening than perhaps should be for a particular level of exertion.

For these people, their aerobic system is so bad that they need to walk to stay in "zone 2". It stands to reason that if they are doing a HIIT session then they are very quickly in the territory of zones 3 and 4, so we are looking at lactate threshold or critical power levels of exertion. So you are looking at more than 60-70% of power coming from anaerobic metabolism. That puts a lot of stress on the body.

For these people to develop their aerobic systems, they need to do a lot of slow jogging or fast walking. Eventually if they do that enough then they'll be much healthier, find HIIT sessions easier and recover much faster. People that spend too much time doing intense exercise will eventually end up with some degree of autonominc dysfunction. I've seen it plenty of times with HIIT people that want to start doing running. They train multiple times a week. Look stressed and knackered. Think they are aerobically fit but can't run a 5km in less than 20 minutes and can't run a 10km at all.

I do HIIT all the time, e.g. 20x400m on the track with 3min walking recovery. But as you noted, one doesn't do these sessions to increase ability to exercise for a long duration, you do long runs e.g. 25km at aerobic threshold for that. I don't do these sessions to primarily target adaptions to my aerobic system either. Instead, I do HIIT sessions like 20x400m with varying levels of recovery to target different apations. E.g. with long recovery I can target anearobic capacity. With shorter recoveries and a lower amount of reps, I can improve lactate buffering and usage.

Finally, it's reasonably well known in athletics circles that if you improve your lcatate threshold, i.e. increase the intensity that you are able to stay sustainably aerobic, then you end up decreasing your anaerobic capcity. The reason why is that the lactate threshold training reduces your ability to produce lactate.

Source: I've been running a long time and have coached runners of various levels.

Depends what you want to do. Run a fast 5k? Improve aerobic system? Something else? Short fast bursts of running will improve your anearobic capacity. Slightly longer intervals run a bit slower may target your lactate threshold and lactate clearance rates. Slower running for longer distances will target your aerobic system.

As people, and the featured article, notes, short intense intervals may burn the most calories but I would argue for more well rounded fitness you need to do a bit of everything.

Due to HIIT, there's loads of people around the world now who have great anearobic metabolism but non-existant aerobic metabolism. The effects are increased autonomic stress from all the anearobic work and an inability to exercise for long durations without quite a lot of stress on your body.

I'm not an exercise physiologist but I have an interest in it. The article states that more energy is used when the body is gearing up for an activity and I'm guessing this is because if you exercise for only up to a few minutes at a time with sufficient rest in between intervals then you'll end up mostly using the phosphocreatine and anaerobic glycolosis systems which are less efficient than aerobic glycolosis or aerobic lipoylsis. It's why when you start running without a sufficient warm up, you're always a bit out of breath even when running at sub maximal efforts and later on in the same run, even when running faster, your breathing can be super relaxed. The aerobic system takes a while to "spin up". In other words, you start with poor running economy... using more calories to run the same speed but as your aerobic system spins up, your running economy increases and you use less calories to run the same speed.

It's my understanding that by doing the type of exercise mentioned in the article - short bursts - you'll get positive physiological adaptations to your anearobic capacity but it won't have much impact on your aerobic capcity, which I would argue is the more important system to train for everyday operations of the human body!

I've been tracking HRV for about 8 years and can conclude that (for me) any HRV measurement overnight using a wearable or related wearable readiness metrics are largely useless. Now, what I do - as recommended by Marco Altini, an HRV researcher - is measure in the morning, steated with a chest strap. I use his app, HRV4Training which I would recommend [1]. It's the only way to get decent data in my experience. HRV is so senstive to various stimulii you need to measure it under exacting conditions, which you don't really get when you are sleeping. Sleep stages matter, how you are breathing, body temperature, etc.

I think my Oura ring is great but... it consistently records average nighttime HRV of around 15ms, which is implausable. However, when I wake up and measure with my Polar chest strap I'll get a more sensible reading. Fully recovered it will by about 150ms. Hurting after a hard workout it will be around 40ms. Some other interesting experiences with oura/garmin/apple are:

1. Higher nightime HRV after drinking alcohol than abstaining for weeks but then I measure with a strap and it will be low as expected

2. HRV spikes when I get out of bed in the middle to the night to do childcare related things, when it should be lower when walking around

Another thing to note is that I think I have parasympathetic saturation which means due to physiology and environmental factors you actually end up with a super low HRV when you are lying down/resting. Endurance athletes often get it - I run about 100km a week and my resting HR when fully recovered is about 40 bpm, so I guess that's the reason. When I de-train then nighttime HRV goes back to normal.

If anyone is interested in HRV I definitely recommend reading Marco's blog [1], you will learn alot.

[1] https://www.hrv4training.com

[2] https://substack.com/@marcoaltini

I qualified as a CA with EY in London around 15 years ago in banking audit. Left soon after qualifying. Some weeks I clocked in over 50 hours but never usually much more. Never had to do an all-nighter though I knew loads of people who did. Part of the reason I had a good experience was that I was lucky enough to work with an excellent manager who was well organised and knew how to audit without wasting time on spurious nonsense. I had to sacrifice a few Easter bank holidays in busy season but we got back the time in lieu. Outside of busy season was fairly quiet - Thursday afternoon pub lunches etc.

Some people did far more hours than me but I think it was mostly self imposed. A small minority of the partners were twats but the vast majority were mindful of people’s well-being. Friday evening drinks in corney and barrow were sacred and on days I didnt want to work longer I just got up and left to the disbelief of the audit room - they got over it though!

This is definitely true. Distance/time running is the most effective lever you can pull to increase performance assuming your form isn’t completely messed up.

I used to run competitively in my teens. Now nearly 40 and getting back into it. Recently upped distance to 50 miles a week (mostly slow) from 20 and I’m suddenly doing sub 17min 5ks. Couldn’t get below 19 mins before upping mileage.

Very good! Can second that. I run alot and sometimes get knotty leg muscles/tendons. I've found for quad knots, the best way is to jam your elbow into the knot and hold until the muscle releases. For harder to reach areas like IT band then I use a massage gun with the pointy tip but you need to be careful not to bruise the area.

A few questions about this...

Fit athletes can run quite fast at a low heart rate, that in some cases might even be lower than walking for regular people. That is to say, the runners are exerting themselves less from a cardiovascular perspective than an unfit person walking. E.g. I can run 8min/mile pace on the flat at a 120bpm heart rate (around 67% of VO2max). But I know people who have the same (or higher) heart rate by just walking or doing house work. So what exactly are we saying by pointing out that running is bad for you? High heart rates for a long period of time are bad for you? The action of running is bad for you? Something else? None of this research makes sense to me.

But why just running? What about other sports like cross country skiing, or rowing? Mountaineering? What is it specifically about running which is bad? Or are all these other sports bad too?

I had a cardiovascular age test done recently which uses pulse wave velocity [1] to determine arterial stiffness. It turns out my "cardio age" is 11 years younger than my actual age and I run at least 50 miles a week. Mostly slow, some fast. So that seems to contradict some of this research, or the pulse wave velocity test is BS?

On another note, there's so much nonsense in that linked thread above I don't even know where to start. Great timing because I enjoyed reading this hackernews thread [2] about the phenomenon that most info about a subject is wrong and you only really notice it if you are an expert or have first hand knowledge.

[1] https://en.wikipedia.org/wiki/Pulse_wave_velocity [2] https://news.ycombinator.com/item?id=40733956

I have 6.5kW of solar PV and a 16kWh battery system in the UK. On a sunny day I’ll generate about 50kWh and export more than half of that to the grid. The rest is for charging my hybrid car (25kWh) and just general house use.

So far this year, our net grid import is 3000kWh and solar generation is 2500kWh. We have a 5kW heat pump and that uses quite a lot of electricity in winter when we don’t generate too much.

I remember teaching in China nearly 20 years ago and all the kids did this. I thought it was so strange. Crazy music would come on between each class, which was the prompt to start “eye exercises”. They all stopped what they were doing and massaged their eyes and forehead for about two minutes. Then got back to doing whatever they were doing. Non-participation was punished.

When I was living in London after COVID, at first, I didn't enjoy it. I still came into the office but when no-one else was there I realised "what's the point?". The office was exposed as the dull/boring/clinical place it's always been. The people I found going into the office were either those who were young and lived close by and somewhat used work as a social club, or those with nothing else better to do (also me at the time!). Anyone with a family was not there. Meanwhile, I've continuted to work remotely and I moved to the Cotswolds. I swapped a Victorian terrace for a much bigger detatched Cotswold cottage. I have a big garden, a glorious wild flower meadow and sheep grazing adjacent to the garden. There's no traffic on the roads and the nearby countryside is amazing. London is a veritable shithole in comparison. Getting a train to London is like travelling to a different - worse - country.

If I still lived in London and commuted to the office, I would never see my young kids. I'd be out the door by 7:30 and back by 7ish. It would also put a lot more stress on my wife, as she would have to do everything during the day. I'd also get about 30 mins or so a day with my kids. That's terrible. Now, I can play with my kids until 9am and then start work. I finish at 5:30pm and get 2 hours with them before bed. I can also go running during the day.

Switching off isn't really a problem for me because well... work is work. It pays the bills. So I'm quite happy to shut my laptop and forget about it. We had a cabin built in the garden, so my new commute is about 1 minute down the garden to the "shed" during which time I miraciously forget I even have a job in the first place when returning "home". I don't have any work apps on my phone for obvious reasons. I appreciate that's not the same for everyone though.

Regarding cost of commute We've had it drilled into us over the years (gaslighted, even) that it is acceptable for us to spend hours of our day commuting to work and for us to bear the financial burden. Why should that be the case? I used to spend £10 a day on the commute. Commuting 200 days a year, that's £2,000 of my salary I need to spend on just getting to work. For others it is much more. That's absurd but it's just the monetary cost. The opportunity cost in terms of MY time is huge. It's about 2 weeks of the year sitting on a horrid underground train. I realise, you can do things on the train but I guess my point is that being on a train limits you from doing other things like playing with kids or doing some gardening. When recruiters have been getting in touch about new roles I make it clear up front that if said company wants me to routinely attend the office they must pay me for commuting time and the commute cost, otherwise it's a "no" from me. Some companies agree remote is acceptable in that case. I mean, I don't mind paying for the odd trip to the office but on a regular cadence and if it's expected (part of contract), then they must pay.

Also, let's not forget the environmental impact of all this mostly pointless travel to work every day for knowledge workers. How much less carbon would we emit if we stopped doing it? Judging by the dip in CO2 emissions during COVID, quite a bit.

Also an endurance runner and read Pontzer's book. I do enough running for my wife to get pissed off! I agree with you that there's definitely more work which needs doing to understand metabolism in the context of endurance athletes. I don't think his work is outright nonsense though. Here's something to think about...

I ran 21 km yesterday, in zone 2, in a fairly glycogen depleted state. That was about 4:30min/km for 21km, with 600m of elevation - about 1500kcal of energy. I didn't eat or drink anything throughout the run. I'm a big nerd, so I took a lactate sample at the end. I didn't hit the first ventilatory threshold for the whole run and that indicates I'm burning a large proportion of fat compared to a normal person (and probably a normal recreational runner).

Afterwards, I ate a banana and had a couple of spoons of peanut butter + honey. A few 100kcal. Fast forward to the evening. I didn't eat any more than I usually would do if I had a few days off running. I went on with my day as normal and recovered fine the next day. I didn't feel hungrier than usual. Fairly standard. My body is well adapted to this kind of exertion. I think my body is quite efficient at doing every day things. I don't get out of breath walking up stairs, for example. Maybe it's fair to say I'm more energy efficient than a regular person. Perhps, I don't need to eat any more than usual immediately after running because I'm burning a high proportion of fat and my metabolism is quite efficeint anyway.

Someone who has a poor aerobic system wouldn't be capable of doing that. They'd likely be running at a much higher heart rate and bonk after 10km having not eaten any carbs the day before. They'd also likely need to eat a huge bowl of pasta afterwards just to feel OK. I suspect this person would feel like crap for the rest of the day (maybe even multiple days... Imagine.. they've likely just done a 10km at VO2max untrained) and I could completely imagine them having a nap or watching TV for the rest of the day as they'd have no energy to do anything else. Their bodies are not adapted to this kind of exertion. They are not efficient. Their body needs to rest to get back in equilibrium.

The energy requirement is the same in both cases but it comes from a different source. In my case the high fat oxidation is acting as a battery/buffer. In the average person, those fat stores are not really accessible when doing anything more than sitting or light walking. Both examples are in equilibrium but present in different ways.

Our son had no screen time and the odd bit of TV up until 2 years old. On his second birthday my wife thought it would be a nice idea to give him an amazon fire kids (because everyone else had one, though not sure how true that is!). A few things we observed:

1. Whilst there IS good content on there. A lot of it is complete nonsense. cocomelon, paw patrol, baby shark, AI generated rubbish etc. and quite a lot of the games are terrible. Toddlers don't know the difference between what is good and what is bad. You cannot monitor them effectively because amazon provides access to all content by default. He would quite easily get through 20-30 apps/videos in one sitting. That's a lot of different content!

2. Instead of reading, playing with his lego, wooden blocks, trainset or doing puzzles, his goto became the tablet. He wanted it at all meal times, in the car, and before bed. If we didn't give it to him, he had a meltdown. So we ended up giving it to him as we didn't have time to deal with the meltdown. Before the tablet, he didn't really meltdown at all.

3. Whilst he communicates well and talks a lot for a 2 year old. When using the tablet, he would completely zone out... "Would you like to eat supper?" ... tumbleweed. That's not great and aligns with TFA.

4. Not sure if correlated because there are lots of other factors at play but his bedtimes became a nightmare. He wanted the tablet, when before we read books like Mog the Cat or similar. Instead of being content with Daddy singing Jelly on the Plate, he wanted the horrid video on the tablet.

5. We live in a lovely rural area in the UK and he stopped wanting to go outside to instead play with the tablet.

6. Again, not sure if correlated but he became more irritable and restless after using the tablet.

7. He would complain there is nothing to do despite the availabily of toys.

And so... One day we told him the computer was broken. Mummy sent it to the factory to get it repaired. And... It's still being repaired to this day.

The first day was hell but now he's stopped asking for it and he's back to his normal self.

Perhaps we'll introduce it again when he's a bit older.

Can probably add a few more kW of solar PV but I'm not sure there's much point unfortunately. What I've realised is that the limiting factor is really the rubbish UK weather. Over the last 4 weeks the most I've generated in a day is 5kWh. I guess that will change in a month or two though when the days get longer and hopefully sunnier.

Live in rural England and have a heat pump with 7kW of solar PV and 16kWh of battery.

Any outdoor temperature around 10 degrees the, heat pump keeps the house at 20C using about 1kW of power and is only drawing power for half the day. Warmer than 10C, the amount of power it uses is negligible. However, today it’s -1C and the heat pump is drawing nearly 3kW all day to keep the house at 20C. Imported 40kWh from the grid today mostly for heating. Price per kWh is about 27p. Not cheap.

It all balances out when the days get longer and sunnier. Can generate 50+ kWh of electricity, which more than covers our usage so we export a fair bit.

I set the heat pump to heat water to 55C between 2am to 5am and again between 2pm and 4pm if necessary. We also divert any excess electricity after usage and charging batteries to heating the water tank via immersion heater. Had 4 family member over for Christmas and we didn’t run out of hot water once!

Pretty happy with it overall.