OK, so here’s a question then.

Zwift related for me, but could just as easily be outdoors.

45 mins at 92-95% of max HR, so basically flat out from the go to the end.
1hr30 at 65-70% of max HR, so a nice cruise all the way.

Assuming we accept certain things like the ‘afterburn’ effect and take the higher intensity as working the body harder… Which is likley to have the best calorific/weight effects out of the 2 ?

Which is likely to produce the higher levels of fatigue ?

This is a complicated question and depends on your physiology, your eating strategy and IMO where you’re starting from.

Yeah, i guess….

Lets assume ‘we’ are fairly average, with your generic average/poor diet, the odd beer, take away, bad things, good levels of fitness and starting at 90kg then, having been training/exercising regularly for the last 10 years.

I’m no expert, but i’d expect 1hr30 at 65-70% of max HR to burn more calories and have a greater long term impact of weight loss, but 45 mins at 92-95% of max HR to cause more fatigue (unless that’s how you always ride).

When I say it depends on your physiology, I mean to a large extent your genetics.

I’d read one of the many training books on the subject, if I were you.

I’d read one of the many training books on the subject, if I were you.

Books don’t know my genetics…. I’m also assuming you’ve read it ?

Over 90% for 45 mins that’s race-level effort and typical for someone pretty well trained and conditioned. Are your sure your MHR is correct – have you done a proper ramp test?

Surely it has to be the longer, less intense effort for weight loss? Or am I missing something?

Also feeling queasy at the prospect of 90%+ for 45 mins!!😂

My guess would be on an intense 45 minutes burning more calories than a 90 minute cruise. Keep in mind that you also burn calories when you’re resting, so 45 minutes of resting calorie burn has to be added to the 45 minute workout to compare it to the 90 minute workout.

Edit. Forgot to add that some actual research on the subject would be much more useful than relying on a bunch of people on the internet guessing.

From my own experiences, relatively brutal (either extreme under-over intervals, or something more steady near your FTP) sub 1 hour sessions will burn far more Calories and produce more fatigue.

Lower intensity rides will burn more fat as a %, but you will burn less Calories both during and after the exercise.

Broadly speaking, the same will apply to heart rate as power, but your rate will be influenced by other things besides your activity level.

45 mins at 92-95% of max HR

I’d be very surprised if you are actually able to do that, and if so it will be mentally very taxing and I would imagine will burn more calories, it’s a much higher work rate and higher afterburn.

IAE I’d be googling this rather than relying on armchair experts!

Books don’t know my genetics…. I’m also assuming you’ve read it ?

Er.. the point about books is that they contain lots of information, some of which may be pertinent. A book is different from a training plan. You need a coach for the latter.

So does the higher calorie burn automatically imply more weight loss? Or is that too simplistic? What about if you spend the following 45 minutes troughing a bargain bucket as a reward?

If this is a weight loss strategy, you need to consider the fatigue of the intense duration.
You could do a long easy ride every day, but a very intense session could lead to less riding time over the duration of a week for example.

Exercise as a weight loss technique isn’t the way to go btw

I think you’ll burn more calories riding for 90 minutes, but be more fatigued riding at 92-95% max HR for 45 minutes. Whether either of these translate in to weight loss, who knows.

Riding at 95% max HR would be incredibly difficult, even for ‘just’ 45 minutes. I have never managed that and I have turned myself inside out on more than one occasion. (I think you’d be better off using power to measure the effort, HR is too variable.)

OK, if i race zwift for 45 mins i average 168-170bpm, with a max i’ve ever seen at 183. So considering the first 5 mins is gettig HR up to speed puts my race effort over 90% ?

That’s a 92-93% average. I was only saying holding 95% max HR for 45 minutes would be very difficult and something I’ve never managed. You might be able to do it.

Back to losing weight, I assume you mean fat. I think the longer ride in conjunction with controlling (or reducing) your calorie intake ‘should’ mean you’ll end up over time with less body fat, and the longer ride should also be less fatiguing. (It’s possible you could end up losing fat, gaining muscle and actually weighing more.)

I doubt the riding on its own without paying attention to what you eat will be very productive in losing body fat.

In terms if fitness, HIT and regular are about the same but obviously the duration varies. Even running up a flight of stairs can equal a long walk.

In terms of calories (for weight loss) forget exercise. Lowering caloric intake is the only way, according to the most recent research.

yeah, I think cromollolly has it there. I’ve not got the willpower for it but I think it’s the way to go for sheer weight loss.

… and cutting cals (further than currently) while smashing out zwift races may not end well, so gentler rides

IAMNtheauthorofadietbook

with a max i’ve ever seen at 183

Unless you’ve properly gone for a max, this won’t be your max.

I forgot to say that once you have lost the weight, if that is your goal, exercise is crucial to maintaining the new weight, apart from the other benefits

Of course you can loose weight through exercise.

Eg my commute. If you’re burning 1500 calories getting to work and back they have to come from somewhere

It depends.

If weight loss is your goal you need to look at it longer term.

I am currently doing lots of short 1hr medium type efforts (around 180-200w av, ftp is 250ish) with a fortnightly 2hr 200-220w session. At this pace, I can also easily swim for 30-1hr in a lunch break and fit in 1-2 gym sessions with a med pace 20min 5k row and weights/stretching.

I haven’t lost weight…but I’ve lost fat.

This is approach seems to be much better for me as I’m a bit detuned from young kids – last year I was trying to do what I used to do (smash out a 20mph 3 hr ride, pop out for a casual 100miler you know) and I was ending up with loads of illness and injury because whilst I could complete the session it destroyed me so bad it took me ages to recover.

So long answer to say I’m in favour of lots of shorter moderate sessions that are sustainable till you get to your target weight / fitness plateaus/ you are free from niggles. After that its time to use HiT

I also find, a couple of 350-500c burning sessions easy to cope with, with normal eating. If I do a harder session, say burning 1500c + I get the massive munchies and I’m sure I eat way more than 1500 in ‘recovering’

High intensity intervals much better for weight / fat loss than plodding along for hours.

Unless you’ve properly gone for a max, this won’t be your max.

I wouldn’t have said if it if i hadn’t done it with a little bit of scientific planning.

Can see where your name comes from.

From what I understand HIT and regular exercisr can burn similar amount of calories just one is more time efficient.

Also the HIT routines require you to go proper balls outs. A sustainable good level of effort is not enough you need to be properly done by the end. The high really does mean HIGH.

Also depending on your genetic make up you may get better results from one or the other.

Regarding fat loss I’ve got better results in the weeks I was much stricter on the diet.

I do 3×1 hour HIT weightlifting sessions per week. Some sessions I can barely lift my arms to shampoo my head when showering afterwards. No heart rate monitor stats but I’m trying very hard.

The weeks I was really controlling the portion sizes and the foods I was eating I got much better weight loss.

I was surprised at how small portions you can eat and still function well in the gym the next day.

And remember the less you weight the food you need so as I lost weight I would reduce the portion size by a little bit.

If your main aim is just to gain strength and don’t care about weight then maybe this strategy is not for you.

I’m 180cm tall I went from 90kgs to 79kgs in 3 months and that included xmas and a few weeks of hols. 24% body fat down to around 19%. Not bad for only 3 hours exercise a week.

“max I’ve ever seen” doesn’t imply that tho does it?

Fair enough if so, riding 15 beats below max for 45m is proper racing stuff.

OP needs to do a proper maximal test to determine what it is, not some estimate from Zwift. If you are doing more than a couple of race-intensity efforts per week, you’ll more likely end up fatigued / over-trained than losing weight.

If you are doing more than a couple of race-intensity efforts per week, you’ll more likely end up fatigued / over-trained than losing weight.

Fatigued is quite a common feeling, but my performances in Zwift/real-life don’t really seem to suffer for it. I’m not sure what the difference is between tired, over tired, fatigued and destroyed. After races i’m completely spent, the HR is up around 180 at the end so up in the higher end of where i’m about to expire…

Lets establish something here, this isn’t a bragging competition, this isn’t me bigging myself up, whether i’m at 90% for the 45 mins, or 93% or indeed 95% doesn’t really matter, it’s more the context of the question.
In the same way of the KFC eating thing, i’m eating what i eat on a given day, whether it’s a hard day or a long slow day, the eating isn’t changing (so can kind of be ignored).

I’m well aware of where my weaknesses are as a person regarding eating and i’m also aware you can’t out-train a bad diet as they say, but i can optimise what i do or don’t do within certain parameters of course.

If the question cannot be answered then that fine, that’s all OK. It wasn’t really supposed to be about ‘me’ anyway, but more a general discussion on which type of exercise is best suited to weight loss, assuming all other factors are equal.

Jairaj, thanks for your input. 🙂

Time isn’t a major issue for me, i can easily put in 5-10 hours if i were physically capable without impacting family time etc.

Strength and gym stuff doesn’t massively interest me though. I exercise for fun and pleasure, i get very little of either from weights.

I know everyone is different but I’ll echo what others have said, 90% max for any significant length of time is pretty good so either you must be very mentally strong or you’ve a bit more top end than you’ve seen.

My max hr is 202, my 20min tt is 178bpm (so 88%) this hurts and I’ll need a bit of a sit down afterwards, my 2 to 3 hr bloody hard so I fall off / hurt and have tunnel vision is 166bpm (82%). I train with power these days but the hr stuff has stayed pretty much static, I just put out slightly more or less power for the same bpm.

Fatigued is quite a common feeling, but my performances in Zwift/real-life don’t really seem to suffer for it. I’m not sure what the difference is between tired, over tired, fatigued and destroyed.

Fatigued and destroyed is getting up in the morning after 8 hours sleep, sitting on the sofa with a 1000 yard stare, aching all over not being able to contemplate moving, feeling cold, then immediately falling asleep again.

I’ve been there a couple of times now at the end of training blocks and its quite unpleasant.

I wasn’t suggesting to do weight training was just explaining my routine. It was more a comment that high intensity short exercise is working for me. Previously 3 hours of exercise was just one ride out of a few a week. So I’m surprised by the gains or losses I’ve seen.

If the diet isn’t going to change then I’d do a experiment with couple weeks doing lower intensity but longer rides and a after that try higher intensity and shorter rides.

Weight your self regularly and see which method works for you.
Try to keep everything the same so try and eat the same things and quantity during both methods.

Newer wisdom is to go for high intensity training compared to older wisdom of slow and steady. While many have seen great results with high intensity training it’s not for everyone. So either get a genetic test or try both methods to see what works. It won’t be very scientific but hopeful will show an indication for what works for you.

Of course you can loose weight through exercise.

That’s all the science told then

Eg my commute. If you’re burning 1500 calories getting to work and back they have to come from somewhere

If you are 90kg and cycle continuously at a rate of around 20mph for 1 1/2 hrs on average you will burn 1500 calories. If you eat 4000 calories per day you won’t be losing any weight.

People drastically underestimate the amount of calories they take in and massively overestimate the amount of calories they can burn by exercise.

Buy a fatiguWiz a weightWiz and a caloriesWiz

or use common sense 😉

I’d say lots of short hard intervals would burn the most fat as the calories burnt afterwards are going to be more biased towards fat?

But, you couldn’t do that every day, you could do a lot of very long z2 rides though which would burn more than a few interval sessions?

Books don’t know my genetics…. I’m also assuming you’ve read it ?

Yea. But you’re not a unique snowflake with completely unique characteristics, you’re 99.9recuring% the same as Mo Farah, Chris Hoy and Bez from the happy mondays. You can’t ask a question then say an answer doesn’t account for something even you don’t know.

Using the workout builder on Training Peaks, they come out as approximately the same TSS

1.30:00 at 0.65 IF = 63TSS

0.45:00 at 0.92 IF = 63TSS

So physiologically, they should be equivalent in terms of fatigue.  But it depends where your aerobic threshold is, and your lactate threshold.  I can ride all day at 65% intensity and not feel it later, but a 45 min workout/race at 92%+ intensity will have me hurting for days.

AFAIK, the idea that different types of activity or level of effort are more or less efficient at burning fat are nonsense. The important thing is how many calories you burn. If you eat more calories than you burn, the excess will be stored as fat. If you eat less calories than you burn, you body has to burn fat to make up the shortfall. However, it’s impossible to sustain high intensity exercise if you are starving and burning fat, so you just won’t be able to train hard if you are aiming to lose serious amounts of weight and you won’t be able to lose serious amounts of weight if you are training to increase power.

Hols2 .

That’s already been proven completely wrong by genetics *

* We did this last month with the op and it aS rubbished then .

I’ve managed 94% for an hour during a CX race so it’s not uncommon in a race situation. Although excercising for that long at that rate requires pretty accurate fueling to ensure you don’t bonk, whereas less intense for longer should require less immediate fueling.

https://www.strava.com/activities/2060282395

https://www.strava.com/activities/1919234436

There are so many variables, perhaps it’s worth experimenting on yourself, noting your intake for a couple of months and see what the effects are for each type of training. I think for me training peaks gives a good indicator of my form and fatigue. If your not signed up perhaps give the trial a go?