Top
Best
New

Posted by bookofjoe 7 hours ago

Exercise intensity influences body composition in healthy older adults (2025)(www.maturitas.org)
165 points | 140 comments
yawnxyz 2 hours ago|
> Healthy older adults (n = 123, average age 72.0 years, body mass index 25.8 kg/m2) completed three 45-min supervised exercise sessions per week for 6 months. Participants were randomised to treadmill-based moderate-intensity training (n = 45), or high-intensity interval training (n = 41) or a low-intensity active control condition (n = 37), with individualised heart-rate prescription. Dual-energy x-ray absorptiometry was used to quantify body composition at baseline, and at 3 and 6 months.

ok they didn't even include light/moderate weight lifting as another control, so this is a fairly poorly executed study

basically it comapres hiit with treadmill walking in which case yes, it's slightly more useful, but hiit also causes a lot of damage in a lot of ways

fsloth 51 minutes ago|
"hiit also causes a lot of damage in a lot of ways"

Oh! I didn't know about this. Are there any references you could quote?

Systemerror7A69 5 hours ago||
I think it's important to note that this study, at least to my understanding, compared cardio training - not weightlifting or resistance training. Participants did 3 weekly sessions of either low intensity, moderate treadmill excercise or HIIT ( 4-min @ 85–95%, 3min 60-70% ).

I get the feeling some commenters here are misunderstanding this as a lot of the discussions seems to center about weightlifting.

Additionally from what I understood the biggest difference was that the HIIT group lost less muscle while fat loss was roughly the same.

thesz 4 hours ago||
HIIT is a borderline strength training.

Consider Tabata protocol.

It is supermaximal effort protocol, participants are required to exert maximum effort repeatedly.

The duration of active phase of Tabata is 20 seconds, half of approximately 40 seconds after which maximum performance (power output) drops significantly, because body switches to a different energy system.

In my experience, Tabata squats are done in range of 16-21 per 20 seconds of active phase. So, basically, Tabata squats are equal to somewhat less than 8 sets of 16-20 repetitions done close to failure. The failure usually come after first active phase, so that's why there are "somewhat less than 8 sets." I personally define failure as breakage of exercise form or exercise pace, and this is what I and others experience in Tabata squats.

And you know what? If you go close to failure, muscle mass and strength grow in the range of 5 to 35 repetitions [1].

[1] https://www.youtube.com/watch?v=dN_c4sQwfTI

PS

Other HIIT protocols are similar. For example, 3 one-minute-active-phase-one-minute-rest supermaximal protocol also leans close to "3 sets of 35 repetitions done to failure" - squats' pace noticeably quickly deteriorate to 1 squat in two seconds.

storus 3 hours ago|||
Tabata is the craziest workout ever, with Tabata sprints I couldn't feel my legs 3 minutes in and after 4 minutes all I could do was to vomit while shaking on the ground. 7-minute workout with as many reps as possible (even if not in perfect form) helped more overall.
alfiedotwtf 3 hours ago|||
So that’s for building muscle, but what about if you wanted to lose a few kilos and increase endurance for long distance running? What would be the way to go to optimise your time?
projektfu 37 minutes ago|||
Eat less to lose the weight. Tirzepatide or something similar makes that a lot easier.

Tabata (the sprint/recover running technique) was developed, I believe, to increase VO2-max. It should help with overall endurance, and you can go on a long run each week. That would probably be efficient.

nemomarx 3 hours ago||||
If you want to increase endurance for running I think the general suggestion is to hit the track and do running? Get your mile time down or similar.

In my personal experience I've found strength training better for losing weight than just cardio but any activity will help a bit. You'll really need to adjust your diet in some way for it though, or at least start counting and keep your calories steady as you do more activity. Trying to outburn what you eat takes like an hour of exercise a day otherwise, it's tough.

Earw0rm 2 hours ago||
Strength training has more of a positive effect on body composition.

The problem with doing a lot of cardio is that you need muscle to burn calories (especially so without injury and as you get older), and too much medium intensity cardio will start to chew up lean mass.

No harm in doing a bit of both though, especially if your goal is fitness/maintenance rather than maximum strength or a particular look.

meroes 2 hours ago||||
Longer slower running burns more fat because your body isn’t forced to use as much glycogen as faster paced running.

I guess the answer for optimizing time is to get a home treadmill if removing the commute to a trail/track will make the timing work.

hobonation 2 hours ago|||
Overnight hiking. It's not boring, and you get 7 hours of hiking in with a backpack per day.
tomjakubowski 1 hour ago||
And if you're Andrew Skurka, in peak form, you'll get 15 hours in per day.

https://www.keithfoskett.com/the-andrew-skurka-interview/

bitexploder 5 hours ago|||
This study is completely unsurprising to me having read a lot of fitness studies over the years. Work muscles harder, muscles get stronger. That is how hormesis goes. The fat loss is simple energy expenditure. You are still producing roughly the same work as someone doing more steady state work. Only effect that might come up is post exercise metabolism elevation but that effect is relatively small and probably present for both groups.
ralferoo 4 hours ago|||
> The fat loss is simple energy expenditure.

But it's not, unless there is a calorie deficit.

If you do aerobic exercise, almost all the energy comes from burning fat. Because your body will have used very little glucose, you're unlikely to feel particularly hungry after that exercise.

If you do anaerobic exercise, almost all the energy comes from glycogen stores. Your body will crave carbohydrates immediately after exercise, and only resort to glucogenesis burning fat if you don't fuel enough afterwards.

There's a significantly higher risk of over-consumption after doing anerobic exercise and aerobic exercise because your body wants to replace the glycogen that got used up.

bitexploder 2 hours ago|||
"If you do aerobic exercise, almost all the energy comes from burning fat. " This is directionally incorrect. Your body will burn both concurrently. For low intensity aerobic exercise, fat is used as the dominant energy source. However even at moderate intensity levels like jogging and "zone 2" aerobic you are 50/50. At higher intensity you have crossed the inflection point and are using more glycogen than not. All strictly aerobic exercise. And it all works on a balance anyway. You use glycogen, it gets replaced until everything is topped off. Doing that means it isn't getting converted to fat.

Both forms of exercise are shown to have an "anti-hunger" effect.

And unless you are walking, your body is also shunting blood away from your gut which also has a secondary hunger dampening effect as it doesn't resume blood flow too it immediately.

So for anything we would call aerobic exercise, that is zone 2 "cardio" or greater, I would have to disagree with your main claims about it.

ralferoo 2 hours ago||
> This is directionally incorrect. Your body will burn both concurrently.

For aerobic exercise, your body gets around 95% of the energy from burning fat. If you are doing exercise where you are 50/50, then it is by definition no longer aerobic exercise but anaerobic.

Anaerobic exercise starts at the point that your body is forced to use glucose from glycogen to provide energy because you have reached the limit of the energy your body can produce from burning fat, because your body can't provide oxygen at the rate required to do so.

kazinator 1 hour ago||
There are two exercise intensity thresholds related to respiration: VT1 and VT2 (ventilatory threshold).

Everything from minimal activity far below VT1 to VT2 (a.k.a. "lactate threshold", LT, a.k.a. "anaerobic threshold", AT) is "aerobic".

Near the VT2 limit, very little fat is used compared to glucose. Fat burning proportions as high as 95% are only reached under very light activity. (And/or in glycogen depleted exercisers whose body has switched to fat out of necessity). That doesn't represent the entire aerobic range.

There is aerobic use of glucose (below the lactate threshold, "clean burning") and anaerobic (above AT, generating lactic acid).

A useful parameter is the absolute fat burn rate. Maximal fat burning does not occur at exercise intensities that derive a large proportion of energy from fat. Supposedly, this "FatMax" exercise intensity fairly closely coincides with the VT1 threshold. Here, around 60% of the energy comes from fat.

I'm "fat checking" all this as I type; I used to know more about this stuff, but forgot a lot.

aix1 52 seconds ago||
This article has a graph from a lab test:

https://knowledgeiswatt.substack.com/p/20-120-vs-90-gh-of-ca...

I thought it would help illustrate what you're saying but, gosh, those Y axes aren't making things easy to interpret. 1g of FAT is 9 kcal and 1g of CHO is 4 kcal.

tryagainian 2 hours ago|||
Can you clarify your last paragraph, looks like there’s a typo or grammatical error that states the same outcome for both arguments put forward in the preceding paragraphs.
ralferoo 2 hours ago|||
I can't edit it now as it was posted more than 2 hours ago, but good spot.

"anerobic exercise and aerobic exercise" should have read "anerobic exercise compared to anaerobic exercise".

faangguyindia 2 hours ago|||
some people may become experience increased appetite from workout while others may have hunger dampening effect.

but bigger reason imho is that people overestimate calorie burn from exercises and fool themselves into thinking now it's OK to consume more food.

IncreasePosts 10 minutes ago|||
I would have thought the fat loss comes from hormonal changes, not merely the energy used during exercise.
lambdasquirrel 2 hours ago|||
Also worth noting that not all muscle mass is the same. Too many people read these things and lacking context, they get swindled one way and then another.
nubg 3 hours ago||
can you tldr me if weightlighting will put me roughly in the "hiit" group discussed in the paper, and give me its benefits?
Schiendelman 1 hour ago||
No, you also need cardio. Even if your heart rate goes up while lifting, it's sustained cardio that really improves your cardiovascular health, keeping your heart rate up in zone 2+ for 45+ minutes at a time a few times a week.
proee 3 hours ago||
So warning about super-high intensity workouts. For a good while I would sprint hard as possible up 8 flights of stairs everyday instead of taking the elevator. I would do this multiple times per day (3,4 sometimes 5) with no warm-up/cool-down . Each time I would try to push for a PR, figuring might as well go for it! One day, after about a year of doing this, I noticed my heart rate at the top felt a little off. I tested with my watch and it said I was in AFIB. I was able to get back to normal sinus rhythm via getting zapped at the ER, but ever since then if I push too hard (usually on longer runs, going all out) I end up back in AFIB. Though it will reset the next morning.

This could be pure coincidence, but I would recommend doing proper warm-up and cool-down before going all out with HIIT. FYI I'm in my 40's.

Bogdanp 2 hours ago||
Regardless of the sport you practice, you probably need to be doing some form of periodization. You can’t go for PRs every session because at some point your body stops being able to recover => you get hurt.
JumpCrisscross 2 hours ago|||
You may want to talk to your doctor about potential exercise-induced cardiac remodeling. Not an expert on this at all. But it’s an injury mode that’s been recently characterized due to sudden deaths among young, seemingly-healthy sprinters.
deeth_starr_v 2 hours ago||
Very interesting. I can also get Afib after many years of high intensity exercise
all2 1 hour ago||
This happens to me occasionally, but it's typically stimulant and blood sugar related.

There are some indications that it might be related to ion availability in your body, so copper, zinc, and calcium specifically. You may also consider that HF RF found in phones, wifi, and Bluetooth can do not great things to the calcium channels in cell walls (it essentially locks the channels open in some cases).

There are a lot of factors to this, but these are things I've picked up in my reading for my own issues.

AnimalMuppet 1 hour ago||
> FYI I'm in my 40's.

Bad news: Age is a risk factor for AFIB. The older you get, the more likely it is to happen.

proee 1 hour ago||
Also a significant increase in AFIB risk for runners. I am doing around 10-20MPW over the last 5 years. Not sure if this is enough training load, but I've had a habit of pushing too hard on my runs as well.
fiveg 4 hours ago||
One thing that I think gets looked past in studies like this is the “noob gains” effect. These participants are healthy adults but not highly trained. It’s pretty well known, in cycling at least, that hard interval training is super effective for untrained people or people coming back from a break, but the gains plateau relatively quickly, and the stress of doing this kind of work is hard to sustain for long periods. Another notable thing is that they are doing 45 minute sessions regardless of intensity, in the real world it’s common for lower intensity sessions to be longer, and for those sessions to be a foundation on which higher intensity sessions are carefully added.
bluGill 3 hours ago||
This study followed everyone for 6 months so they probably got past that factor.
pigeonwarz 3 hours ago||
I doubt it. In my experience (at least when it comes to lifting), newbie gains last at least a year. Good chance that if they've been untrained all their life (or the majority of it) that phase is gonna last a real long time.
globular-toast 3 hours ago|||
A year of continuous gains for a 72 year old? I highly doubt it. For a skinnyfat 20 year old, sure.
monkpit 34 minutes ago||
> I highly doubt it.

Not a very convincing discussion point without some support.

bluGill 3 hours ago|||
I stand corrected then.
jcdavis 2 hours ago|||
I've read a looot of physiology studies about running, and the same dynamics hold true there. This is a flaw (IMO) of of the whole "Norwegian 4x4 protocol" you hear parroted around by biohacker/longevity influencer online, of course with 0 nuance or context of the underlying study and its limitations
tryagainian 2 hours ago||
> It’s pretty well known, in cycling at least, that hard interval training is super effective for untrained people or people coming back from a break, but the gains plateau relatively quickly, and the stress of doing this kind of work is hard to sustain for long periods.

This is 100% experience with both cycling and running, and something I worked out on my own early on, prior to the advent of smartphones and even talking to anyone who knew anything.

I enjoy sprinting, both running and cycling, but it’s mostly something I do to regain my endurance ability after a break. Two two weeks of high intensity interval training, and then I’m able to sustain moderate intensity jogging for 30+ plus again, or an hour cycling.

maerF0x0 3 hours ago||
> average age 72.0 years, body mass index 25.8

Careful before you assume you'll have the same outcomes. That's a group of people who are already fairly light compared to the American populace, and likely are suffering from sarcopenia of sorts and have low potential to gain much more muscle. (Protein absorption, hormone profile)

> Dietary intake was assessed using a 3-day food diary at baseline and analysed for total energy intake (kcal) and macronutrient intake (kcal) by a dietician dietary analysis software (Foodworks, Xyris®, AUS).

So this is both recall + ad libitum. The change could be due to hormone profile, the exercise itself, inadvertent changes in consumption, inadvertent changes in NEAT.

froobius 3 hours ago||
Erm that's higher than the healthy BMI range, so not "fairly light". >25 is considered overweight.
jerlam 2 hours ago|||
It's still lighter than the average American BMI, which is around 29. On average, Americans are classified as overweight.
maerF0x0 2 hours ago||
Yes thats what i was referring to, you're both correct on your respective angles.
tryagainian 2 hours ago|||
My BMI is 28.7 at 181cm and 94kg at 45.25 years old.

Am I overweight, not far off obesity?

You probably wouldn’t say so if you saw me.

BMI is mostly only a useful metric when it is.

maerF0x0 1 hour ago||
I'm with ya at 29.4. I carry a lot more muscle than the average populace, so I'm both high BMI and appear to be "fit" to casual onlookers. But dexa says 26% which is about double what I would like.
tryagainian 2 hours ago||
> NEAT

non-Exercise Activity Thermogenesis?

I’m a bit of a fitness enthusiast, but not enthusiastic enough to have come across all the acronyms.

personalityson 1 hour ago||
Insulin -- the fat storing hormone. The opposite hormones -- cortisol and adrenaline mobilize fat tissue for burning. Chronic cortisol leads to fat gain because cortisol receptors become desensitized. Spiking cortisol in short bursts is better than long bouts of elevated cortisol.
lol8675309 4 hours ago||
'were small and not meaningful' why is this on the front page of HN?
tryagainian 2 hours ago|
The perennial question.

Well, at least it’s spurred intellectually curious discussion.

shermantanktop 1 hour ago||
Is it? What I mostly see is people describing their anecdotal experience and opinions about exercise in general.

I assume that only a few of them are actually in the age group of 65-85, so relevance of personal experience is dubious.

To be fair there are some questioning the study methodology and conclusions.

javier_e06 5 hours ago||
Some move all their lives and keep adapting their movements as their age. Others did not move much through the lives and when they hit 60s and they start loosing the mobility, doctors suggest for them to move more, if anything. If you never hiked and you start hiking in your 60s for health reasons. Pick up short flat trails.
gcanyon 1 hour ago||
Everyone talking about strength training: that’s nice, but it’s not what this study was about. That doesn’t make it a bad study, it just means you’re looking for a different study.
HSO 2 hours ago|
this gets reheated over and over…

look at the study period.

hiit is not sustainable beyond a brief period. by definition you can only do a limited amount of high intensity before you get cooked.

what you really want is periodization and looking over long periods and aggregate volumes

More comments...