Best time of day to exercise?

Summary

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Podcast Summary: What's That Rash?

Episode: Best Time of Day to Exercise?
Date: November 25, 2025
Hosts: Norman Swan & Tegan Taylor
Source: ABC News

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Overview

This episode tackles the ever-relevant health question: Is there a “best” time of day to exercise? Inspired by a listener concerned about exercise risks for older adults—particularly the possibility of heart attack or stroke when exercising at certain times—hosts Norman and Tegan dive into what the science says about timing, fitness, age, and personal “chronotype” (whether you're a night owl or early bird). The discussion separates myth from evidence, examines major studies, and leaves listeners with practical advice (plus a few laughs).

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Key Discussion Points & Insights

1. Background Risk: Can Exercising at the “Wrong” Time Be Deadly?

• Listener Helen’s Question: Her husband heard that morning exercise, especially without warming up, is dangerous for over-60s. She wants to know if there’s real evidence of increased risk tied to exercise timing and what factors matter most.
• Norman:
  • Regular exercise reduces risk of sudden cardiac death, heart attack, and stroke, regardless of timing.
  • However, there is a natural spike in blood pressure upon waking. If a person with vulnerable artery plaque jumps into strenuous morning exercise, this spike may rarely trigger a heart attack.
  • Epidemiology studies show heart attacks are more common in the morning, but not exclusive to it.
  • Quote:

    "There is an effect on the risk of sudden cardiac death on time of day, of exercise, time of day, and it's thought to be a problem of blood pressure." — Norman [03:36]

2. What Does the Data Say? (UK Biobank Study)

• The UK Biobank tracked about 500,000 people over years—one of the largest health datasets.
• Key Findings:
  • Morning and evening both show small spikes in sudden cardiac death risk.
  • Exercisers overall had LOWER risk than non-exercisers, regardless of time.
  • Chronotype (internal clock) matters:
    • Morning people exercising in the morning had no extra risk; night people exercising at night had no extra risk.
    • "Fighting your nature" raised risk slightly (e.g., night owls exercising early).
• Quote:

  “So if you're a night person and you exercise in the morning, then you had a slightly increased risk of sudden cardiac death... again at a lower level than you would expect because they were exercising.” — Norman [06:16]

3. Making Sense of Risk

• The absolute risk increase is small.
  • Of 94,489 people followed for seven years, only 629 sudden cardiac deaths occurred (about 100/year).
  • For those with “misaligned” exercise timing, risk might go from 1% to 1.5%.
• Quote:

  "Hopefully that puts Helen’s mind at ease... if your risk... was 1%, it maybe went up to 1.5%." — Tegan [07:37]

4. Is There a “Best” Time of Day to Exercise?

• Norman: "Best time to exercise is the one... that you actually can exercise." [08:00]
• While early morning or late evening are labeled “less favorable” in some studies, doing exercise is more important than perfect timing.
• Nearly half of Australian adults do not get enough physical activity—just getting moving matters most.
• Quote:

  "The time of day where you can take exercise and take it easy, build it up." — Norman [13:47]

5. Starting Out: Pace Yourself

• Don’t jump into intense workouts after a sedentary period, especially if over 40 and unfit.
• Build gradually: start with brisk walking and only increase intensity as your fitness improves.
• “No need for embarrassment if out of breath at first—you’ll improve!” [08:35-09:48]

6. Body Clock Effects and Performance

• Exercise acts as a “zeitgeber”—a cue for your body clock.
  • For night owls, some morning exercise may help nudge the body clock earlier.
• Performance specifics:
  • Accuracy-based sports (e.g., tennis) may benefit from morning sharpness.
  • Power and strength (e.g., weight training) may be slightly better in the evening.
  • These are marginal differences, mostly relevant for elite athletes.
• Quote:

  "In sports where you require accuracy... you are probably better in the morning... but there are plenty of sports where you’re a bit better off in the afternoon." — Norman [10:35]

7. Weight Loss & Timing

• Some studies find morning exercise may aid weight control, possibly due to appetite changes (delayed or reduced hunger for breakfast).
• Individual reactions vary.
• Quote:

  "There is quite good evidence that morning exercise helps you control your weight." — Norman [11:44]

8. Who Exercises When?

• Demographics shape exercise time:
  • Midday exercisers are often retired or not employed, with different health and lifestyle patterns.
  • These differences don’t seem to change the heart risk findings.
• “So many different things that might feed into your overall health.” — Tegan [12:35]

9. Bottom Lines and Practical Advice

• Heart Risk:
  • Know your risk factors (cholesterol, blood pressure) and manage them early—even if young.
  • Don’t skip doctor consultations. Podcast isn’t a replacement for medical advice.
• Timing:
  • Do exercise whenever you are most likely to actually do it.
  • Build up gradually, listen to your body, and don’t get hung up on the clock.

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Notable Quotes & Memorable Moments

• On ‘Fighting Your Nature’:

  "It was when people were fighting their nature." — Tegan [06:11]
  “Correct.” — Norman [06:14]

• On Absolute Risk:

  "Is that a lot? It sounds like a lot, but it's not really a big proportion." — Tegan [07:12]

• On Practical Priorities:

  “Nearly half, 46% of Australian adults don't meet the physical activity guidelines… one of the biggest ways that we can protect against coronary heart disease.” — Tegan [08:21]

• On Retirement:

  “Don't retire.” — Norman [12:53]
  (Joking about his own age, Norman resists giving up work.)

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Timestamps for Key Segments

• 01:51: Listener Helen’s question & concerns
• 02:36: Does exercise timing increase heart attack risk?
• 04:12: Large-scale study findings on timing and chronotype
• 05:40: The importance of chronotype (“night owl” vs “lark”)
• 06:37: How much does risk actually increase?
• 08:00: Is there a “best” time? (Short answer: when you can)
• 09:48: Gradual progression for beginners
• 10:13: Exercise as a body clock cue
• 10:35: Performance differences by time of day
• 11:24: Timing and weight loss
• 12:01: Who exercises when & demographic factors
• 13:15: Summary: what should you actually do?

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Final Takeaways (in Their Words)

• Norman:

  "If you're worried, you know, everybody should know their cardiac risk factors... So know what your coronary risk factors are and if they're raised, do something about them, which doesn't necessarily always mean...drugs in conjunction with your doctor and not solely based on the information you hear on a podcast." [13:15]

• Norman (on time of day):

  "Just take exercise. The time of day where you can take exercise and take it easy, build it up." [13:47]

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Bottom Line:
Exercise when it works for your body and schedule. Listen to your body’s cues, consider your risk factors, and don’t let the clock be a barrier to simply moving more. The health benefits of exercise vastly outweigh the small, timing-related risks—especially if you match workout time to your natural “chronotype.”

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For questions or feedback: Email the hosts at thatrashbc.net.au
Next Week: More unusual health questions—maybe even Norman’s takedown of retirement!

Transcript

[Claire Nicholls]

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[Tegan]

ABC Listen podcasts, radio, news, music and more.

[Claire Nicholls]

It is a truth universally acknowledged that on one's 250th birthday there should be a celebration. I'm Claire Nicholls and on the Book show we're raising our teacups to Jane Austen.

[Norman]

Why Austen? What is it about her?

[Claire Nicholls]

Authors Colm Toveen, Karen Joy Fowler and more will Explore why in 2025 the Austen effect is bigger than ever.

[Tegan]

That's quite incredible.

[Claire Nicholls]

Search for the Book show and look for Dear Jane wherever you get your podcasts or hear it now on the ABC Listen app.

[Norman]

Tegan when do you take your exercise?

[Tegan]

I am definitely a morning exerciser. I mean, I do exercise at night. Sometimes I'll go to a weight session at night because that's when it's on. But if I was left to my own devices, I would absolutely be exercising at the crack of dawn. It's my preferred time of day.

[Norman]

So here's the second question. Are you a morning person or a night person?

[Tegan]

I'm a morning person.

[Norman]

Right.

[Tegan]

What about you?

[Norman]

I'm probably more of a night person.

[Tegan]

When are you an exerciser?

[Norman]

I tend to do it in the morning because if I leave it to the end of the day, I don't get it done.

[Tegan]

This is it. This is it. So there's like scheduling issues and then there's also like your chronotype. Anyway, let's get into it because that is what we are talking about today on what's that Rash, the podcast where.

[Norman]

We answer the health questions that everyone's asking.

[Tegan]

So this week's question comes from Helen saying, hello, I really enjoy your program and its sister. By which I'm sure she means the health report. Helen says, my husband has recently come across information suggesting that exercising in the morning, especially without some gentle movement, first, significantly increases the risk of heart attack or stroke. Over 60s. Helen says, Is there good evidence to support this more broadly, is there at least dangerous time or a more beneficial time? What are the main considerations for best time of day, level of fitness, age and awake time, that is Night owl or lark? Norman I thought this was Just gonna be about, like, when do you exercise? I didn't realise that people were maybe dying for choosing the wrong time of day.

[Norman]

Well, let's talk about dying first, since that's what Helen's worried about for her husband, maybe even for herself. There's no question that taking exercise reduces the risk of. Of sudden cardiac death. Without any question of doubt. If you've got a background risk of a sudden cardiac death and you exercise regularly, your risk of that drops, your risk of a heart attack drops, and your risk of a stroke drops on the other side of it, and it doesn't outweigh the benefit of exercise. There is an effect on the risk of sudden cardiac death on time of day, of exercise, time of day, and it's thought to be a problem of blood pressure. So if you've got cardiac risk factors, and we've all got cardiac risk factors, even though we might think we don't, which is plaque atherosclerosis in our arteries. But what's thought to happen in terms of time of day is that in the morning, as you get up out of bed, your blood pressure has a spike and that spike is exaggerated. If you then take exercise and if you've got soft plaque in your arteries, that burst of blood pressure can open up the plaque and cause a heart attack. That's the. The behind morning exercise. And when you look at the epidemiology of heart attacks, they more often than not occur in the morning. They don't exclusively occur in the morning, but they more often than not occur in the morning.

[Tegan]

You're really making a strong case for hitting that snooze button, Norman. Like, if I'm already in my bed and I'm like, I don't want to get up and go for a run, it's like, because I might die of a heart attack if I do.

[Norman]

So here's the good news. And the good news comes from a massive study that you and I have spoken about before, which is called the UK Biological Biobank Study. This is where 500,000 people or thereabouts, have been incredibly altruistic and agreed to have their health monitored. A lot of knowledge about their health and well being recorded, their genes measured and their medical records followed through time. And international researchers have been using this database because it's almost unique worldwide and learned a lot from it. So they've looked at this very question about the risk of death morning, midday or night in terms of exercise, and they're able to compare it to the risk of coronary heart disease and indeed, Their chronotype, are they a morning person or a night person? The results were fascinating. There was indeed a morning spike of heart attack. They were looking at sudden cardiac death. So yeah, there was a morning spike, but there was also an evening spike as well. So it wasn't that it was exclusively to the morning, it's that people who exercised in the evening also had a small risk of sudden cardiac death. And remember, I can't say this often enough. Overall, people who exercised had a lower risk of sudden cardiac death. So coronary risk factors did make a difference. So if you had risk factors for coronary heart disease, your risk of sudden cardiac death went up, which is what you'd expect. But your chronotype mattered.

[Tegan]

So chronotype being, are you a night owl, are you an early bird, Are you somewhere in between? We have talked about this before. There's a previous WhatsApp rash on night owls and early birds.

[Norman]

So it turns out that if you are a morning person and you exercise in the morning, according to the UK Biobank study, there's no increased risk of sudden cardiac death. Oh, if you are an evening person and you exercise in the evening, there's no risk, significantly increased risk of sudden cardiac death.

[Tegan]

So it was when people were fighting their nature.

[Norman]

Correct.

[Tegan]

Really, that's.

[Norman]

So if you're a night person and you exercise in the morning, then you had a slightly increased risk of sudden cardiac death. They were the ones who got it again at a lower level than you would expect because they were exercising and vice versa. There was a lower spike in the evening, but it tended to be people who were morning people and exercising in the evening.

[Tegan]

That is wild and a great excuse to get out of going exercising early in the morning with your early bird friend. If you don't want to. Can we just put some numbers around what the increased risk was? Because I think that this is the sort of thing that's like headline more likely to die. If you're a night owl and you exercise in the morning, what actual absolute risk are we talking about here?

[Norman]

So just to give you a perspective here, out of all the Biobank sample, they looked at 94,489 people.

[Tegan]

Okay.

[Norman]

Overall, during a follow up of seven years, there were 629 sudden cardiac deaths.

[Tegan]

Is that a lot? It sounds like a lot, but it's not really a big proportion.

[Norman]

No. So it's like 100 a year. Fewer than 100 a year out of 94,000. And what they don't talk about here is what's called the absolute Risk. So in other words, if I am an evening person and I exercise in the morning, what's my personal increased risk? And they didn't actually do that. But you're asking the right question. Cause you want to know what the increased risk is.

[Tegan]

For me, myself, for example, if your risk, if your absolute risk was 1%, it maybe went up to 1.5%.

[Norman]

Correct.

[Tegan]

Hopefully that puts Helen's mind at ease at least a little bit in terms of the risk of getting out of bed and going for an exercise at all. So can we talk a bit about her subsequent questions, which are really like, is there a best time of day to exercise? What do we know about this?

[Norman]

Best time to exercise is the one. Is the time that. That you actually can exercise.

[Tegan]

Well, that's like what you were saying, right? Like you exercise in the morning because that's. If you don't do it, then it might not happen.

[Norman]

Yeah. Early morning and late in the evening are. The way the paper puts it is those are less favorable times to exercise. But, you know, if you're going in tune with your body, the risk is really low.

[Tegan]

And I think it's worth calling out here that nearly half, 46% of Australian adults don't meet the physical activity guidelines, which are, like you said, Norman, one of the biggest ways that we can protect against coronary heart disease.

[Norman]

And one of the ways you do that, you think that, well, I've got to start bashing the pavement and doing fast jogging and so on. If you're going from the reason why it's safe is that it's moderate exercise. And if you've not had any exercise for a long time and you're getting off the couch to do exercise, walking for 30 or 40 minutes along the flat will be moderate exercise. You'll get out of breath and that will be you getting out of breath. Nobody's saying to you that you got off the couch and you run, you walk, and you walk fast enough along the flat that you're getting out of breath. And don't be embarrassed that you're getting out of breath walking along the flat, because two weeks later you won't be out of breath, which means you've got to add in a hill or you got to walk faster so that you are out of breath. So this progression, which you need to do happens slowly and steadily and your body adjusts. It's not sudden. This is. You know, there's well documented sudden cardiac deaths where you play tennis once a week and that's the only exercise you get or squash. And suddenly from a sitting start, you go and you do this extreme exercise, which is going to raise your blood pressure and your pulse acutely. When you're not fit, that's not good for you.

[Tegan]

So time of day in general, then? So we're not worried so much about, like, having sudden cardiac death. We very much hope that. But we are wanting to optimize our exercise and working in the time of day with that. I mean, for starters, exercise is a really important part of our body clocks and it's a zeitgeber. It gives us time in our brain and our body.

[Norman]

That's right. And if you're an evening person, it might be quite good for you to get up there in the morning and maybe you get this small adjustment which means you're barking away and not falling asleep in front of the telly as easily.

[Tegan]

So what about performance? Are there certain times of day that we are maybe more likely to, you know, if you were in a. In a competition, that that would give you an advantage.

[Norman]

The evidence is all over the place with that. Although, as you would imagine, in elite sports, they've got some greater understanding. So in sports where you require accuracy, such as tennis and so on, you are probably better in the morning, that your accuracy is higher in the morning.

[Tegan]

Because you're more mentally sharp.

[Norman]

Yeah, but there are plenty of sports where you're a bit better off in the afternoon. But I think these are marginal changes. And the reality is, if you qualify for Wimbledon, you'll just take what you get.

[Tegan]

I thought I'd heard before that your muscle performance is better in the evening. Like if you're wanting to do weight training.

[Norman]

I think there's some truth to that. Yes. I think what changes in the morning is the skill base rather than the power base or the aerobic base.

[Tegan]

So that's lifting weights. What if you're trying to shed weight?

[Norman]

Well, you think that physics applies here. You know, calories in, calories out. It turns out that studies of weight loss suggest that morning exercise is better for weight loss. Now, this may well be because it changes your appetite during the day, that you're not feeling as hungry for breakfast and you delay your eating.

[Tegan]

And you what from exercising in the morning? If I exercise in the morning, I am ravenous for the rest of the day.

[Norman]

I have to say. I cycle into work, and when I get into work, I just need something. It's true. But there is quite good evidence that morning exercise helps you control your weight.

[Tegan]

Well, there you go, look.

[Norman]

And the other thing in all this is people who exercise are not necessarily the same kind of people as people who don't exercise. And people who exercise at different times of the day aren't the same. And what we didn't talk about in this UK Biobank study, which I said earlier, is that the group that exercised in the middle of the day were less likely to be employed, more likely to be retired. So there was a different profile for people who are exercising at different times of day. And it would make you think that you're actually going to be more likely, if you're a retiree and exercising at midday, to have a sudden cardiac death. But that wasn't the case.

[Tegan]

But maybe you've also got enough time to make yourself a nice salad for lunch and get enough sleep at night. Maybe you're not quite as stressed. There's so many different things that might feed into your overall health.

[Norman]

Don't get me onto retirement. That's another. Watch that rash.

[Tegan]

Ooh, now I'm really intrigued. Is it good for you or bad for you? Just give me like a top line.

[Norman]

Don't retire.

[Tegan]

That's why you're still working at the ripe old age of 55.

[Norman]

No, 55's down the track a bit.

[Tegan]

You know, of course. Sorry, my mistake. 50. 51. 51.

[Norman]

Thank you.

[Tegan]

But, yeah, bottom line, two bottom lines. One, if I'm worried about a heart attack, what do I do? And two, is there an optimum time of the day to exercise for my health?

[Norman]

So the answer to the first one is, if you're worried, you know, everybody should know their cardiac risk factors, even from your 20s and 30s, once in that decade, each decade should know what your bl. You should know what your cholesterol levels are so that you can actually do something about them, even if it's a lifestyle change. And sometimes you'll find very high levels, which means you need medications and that will be life saving. So know what your coronary risk factors are and if they're raised, do something about them, which doesn't necessarily always mean.

[Tegan]

Drugs in conjunction with your doctor and not solely based on the information you hear on a podcast.

[Norman]

Exactly. And secondly, time of day, just take exercise. The time of day where you can take exercise and take it easy, build it up.

[Tegan]

What did you do today, Norman?

[Norman]

Cycled into work.

[Tegan]

I haven't done my exercise yet, but I'm thinking of going for a swim tonight.

[Norman]

Good.

[Tegan]

Well, thank you so much, Helen, for the question. You can email us your [e-mail] au we love having a go at answering them. Maybe you will be the person that asks us about retirement so Norman can unpack his answer that he gave me.

[Norman]

Before and we've had some feedback on acupuncture and dry needling.

[Tegan]

Yes, so we had this email from Chris about acupuncture who Chris was very sceptical of it because they tried it as a low back pain treatment. Didn't really work. However, Chris has an N of one involving Chris's dog. She was a German shepherd, had a dreadful issue of hip dysplasia and spinal pain. We reached the point where the vet advised we could do no more apart from lots of drugs. Anyway, a friend suggested acupuncture at that stage, bj the dog had to be lifted into the car and her back end swayed like a drunken sailor, frequently giving out. When we arrived at the acupuncturist said he could help putting needles all along her spine and her back legs and paws, leaving them in for about half an hour. She looked like a hedgehog, but she took it out without any sign of complaint or discomfort. Chris writes once removed, she stood up, shook herself and walked steadily out of the room and to my shock jumped back into the four wheel drive. She was like a new dog. No way she could have been influenced by the hype around it. So it convinced me that acupuncture works for. Well, Chris says some people. Maybe he should have said some creatures.

[Norman]

Some beings, some human and non human animals. Well that's true. I mean it's hard to ascribe a placebo effect to a dog. So well done. I'm glad that BJ's back on her feet.

[Tegan]

Me too. Thank you so much Chris, as always. You can email your questions, comments, feedback, dog stories to that rashbc.net au See you next week. See you then.