[Angela Foster] (0:00 - 0:29)
Amazing. So for a woman listening to this, who is, let's say someone who's kind of intermediate level, right? This is not beginner, they're used to doing resistance training and maybe some HIIT themselves or classes.

When you talk about your research in relation to HIIT, are these short intervals that they were doing, but they have quite long recoveries, are they HIIT sort of on its own in terms of a cardiovascular based activity or are they using weights or can it be all of the above? Are there any specific requirements we should be thinking of?

[Dr. Abbie Smith-Ryan] (0:29 - 2:11)
Yeah, I love it. Thanks for bringing it back to what matters most. And it really is, it can look a lot of different ways.

Typically in a laboratory based setting and what we leverage a lot of work on is with high intensity interval training of one minute hard, one minute rest up to 10 times. That's kind of our base model based on several things that we've looked at. One interesting thing, we've actually looked at some genetic mice models between male and female mice and women and female mice respond always to this exercise approach.

I say always like it's in mice, but we know that the muscle and the mitochondria are going to respond pretty quickly. And a lot of this leverages some of initial Martin Gabala's work on HIIT. And it's very quick.

So we know that you can get an effective metabolic load and stimulus in muscle protein synthesis in just one to two sessions a week with effects we've seen in three weeks. And I'll say, one of the things that we've also seen is specifically related to visceral fat. And so HIIT training is really seems to be the primary method of training that helps reduce visceral fat.

Now we can't spot reduce, but because of the metabolic demand of high intensity interval training, our group and others have shown a decrease in visceral fat. However, it does seem to be more effective if you have more visceral fat, like you're not going to go from zero to zero. But if you have more visceral fat, HIIT in shortest three weeks appears to decrease that visceral fat, which can be really effective for midlife women.

[Angela Foster] (2:12 - 2:30)
And really effective for time poor individuals, right? If your time crunched one minute on one minute off, I mean, it's a really efficient workout. Is that just literally like doing running or cycling or rowing or something like that?

Or is it for people who like, say, for example, they wanted to do sled pulls or kettlebell swings? Could they do that?

[Dr. Abbie Smith-Ryan] (2:31 - 3:23)
Yeah. So typically it's more of an aerobic based training just to get the part of it is leveraged heart rate. So elevating the heart rate for an extended period of time.

And so typically it's, you know, running, biking, swimming at an intensity that you could not hold for a minute and a half, and then you rest for a minute. Now you could do that probably with a sled push, but if you are doing that effectively, you're not pushing that for a minute, but it can look different. Like if you, it does to me come down to time.

You can still see benefit from a sled pull in a HIIT type of a workout. I would call that more of like a sprint interval training or a circuit training. You can see those benefits.

It's just working a slightly different energy system. If I'm going shorter, I'm not leveraging as much of my fat utilisation. I'm more leveraging things like our phosphagen system and our glycolysis, which is also helpful.

[Angela Foster] (3:23 - 3:27)
So this is tends to be specifically one minute on one minute off.

[Dr. Abbie Smith-Ryan] (3:27 - 4:16)
Yeah. And we've looked at different protocols. So for instance, if you are someone that wants to see more of those cardiovascular adaptations, then a longer interval in a shorter rest interval can be beneficial.

So sometimes two minutes on or four minutes on with one to two minutes off. You hit the nail on the head when we talk about, like, I think long, slow distance in zone two training is great, but we're talking about a group of women that have minimal time to train and we're trying to see benefit. And that's where this HIIT comes in.

If you have 20 minutes, we all have 20 minutes, and even there's lower data or even more data that shows lower time is also effective. So even if you only have time for five intervals, 10 minutes, you'll still see a benefit. It just won't be quite as large.

[Angela Foster] (4:17 - 4:36)
Interesting. Very effective. I've also noticed that by splitting out the resistance training from the HIIT, that actually personally helps me recover faster.

When I try and mix weights and cardiovascular aerobic training together, you can end up sort of leaving everything on the floor and then you don't have energy for your kids and your career and everything else.

[Dr. Abbie Smith-Ryan] (4:37 - 5:24)
Well, it's working different. You have different goals. So I agree 100%.

And at the same time, sometimes what I'll do is add HIIT after I do resistance training, if that's like a top off or I don't have a lot of time. But you're exactly right. If you're doing HIIT and resistance training, something's going to be sacrificed.

So another word to the wise is always do the training session first that you're trying to get the most out of. And sometimes if my goal is to get the most out of my aerobic or cardiovascular, I'll do HIIT first and then finish up with some repetition weights. And I'd flip that if days I don't have.

So yes, if you have the option to split them, I would 100% agree it's better for training volume and outcomes. But if you are still crunched for time, then do the one first that you that you want to get the most out of.

[Angela Foster] (5:24 - 5:34)
It sounds like you're still splitting them. So you're kind of doing resistance training though, and then HIIT as opposed to it's all muddled in together like a kind of traditional class, right, which then doesn't stimulate quite enough in anyone.

[Dr. Abbie Smith-Ryan] (5:35 - 6:34)
Yeah. And one thing actually that we've done too is used high intensity resistance training. So a lot of times people are doing a class or they're doing circuit training, which is beneficial, but it goes back to load.

And one of the high intensity resistance training methods that we've used in several papers and actually recently used in our perimenopausal women is trying to do a load that you can only lift six to eight repetitions. And you do it three sets of leg press or a push, a bench press, a lunge, a shoulder press, a bicep curl, and a tricep extension. And that's done with three sets, 30 seconds in between each set, two minutes in between each exercise, all done very heavy in about 30 minutes.

And another way we see that a lot, that increases heart rate much more than let's say a traditional resistance training workout. And so it's this idea of load and minimal time.

[Angela Foster] (6:34 - 7:02)
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Interesting. So you're taking one exercise, 30 second rest between sets and then a two minute break, and then you're moving to the next exercise too. Okay.

I'm going to try that. Sounds quite fun.

[Dr. Abbie Smith-Ryan] (7:02 - 7:12)
And it's actually, I love doing it when I'm crunched for time, because you're going six to eight reps, you're holding or doing a weight that you can only do six to eight repetitions. So it's heavy, but you get through it pretty quickly.

[Angela Foster] (7:13 - 7:34)
Yeah, that sounds fun. You mentioned Dr. Martin Gabala's work there and the longer intervals. So if we look at kind of the Norwegian four by four, that's typically talked about in terms of improving VO2 max with the four minutes on three minutes off, will that pull as efficiently from things like visceral fat and improve metabolic health as well as the one minute on, one minute off?

[Dr. Abbie Smith-Ryan] (7:34 - 8:46)
Absolutely. I just find that we've even played around early on in my career of what is the best method. We played around with two minutes on, one minute off.

And the four by four is amazing. It's just hard to do something that hard for four minutes, especially if you take someone that's maybe a non-athlete. Whereas we have found that one minute on, one minute off, you don't need any special training.

You can kind of gut out for a minute on, you can do anything for a minute. And not always the goal is, it's not always an increase in VO2 max. And so, yes, there are so many different approaches to take.

I don't know about you, but, and this is where we would say I would take a female midlife. If I told a woman to do repeated four minute protocols, they would get it done, but it would take a lot of mental, you got to get yourself pumped up for that. And then it takes recovery.

Whereas a one minute on protocol, like it's just a lower barrier and you can do it on your own. And so there's just more intangibles, but yes, the Norwegian four by four is very effective. So as a one minute on, one minute off, a lot of Gabala's early work was repeated 30 second bouts like wind gates.

It just requires a bit more specialised equipment to add the appropriate load.

[Angela Foster] (8:46 - 9:05)
I found when you go on the shorter intervals, like if you're doing it, for example, in a gym on a treadmill, it's actually quite difficult to get the treadmill even fast enough to get the stimulus. So I found that like tilting, like inclining, should I say the treadmill? So you're going uphill and that also seems to help with injury risk, right?

So there's other ways people can make it challenging.

[Dr. Abbie Smith-Ryan] (9:05 - 9:29)
A hundred percent. And I love actually recommending to do something that you're not good at. Like if you're a runner, go do the rower or go swim because your heart rate gets elevated more and you get to a point where it might not rise as much.

And then the other piece you mentioned is interval training is, it does seem to be better for injury because it's lower volume. You're getting the same benefit with lower volume.

If you’re a woman in midlife and short on time, HIIT may be one of the most efficient ways to improve metabolic fitness and target visceral fat. In this conversation, Dr. Abbie Smith-Ryan breaks down the exact HIIT protocol her research group uses most often: one minute hard, one minute recovery, repeated for up to 10 rounds.

KEY TAKEAWAYS

The 1:1 HIIT Protocol — One minute hard followed by one minute recovery is the base model Dr. Smith-Ryan frequently uses in research.
Visceral Fat Can Respond Quickly — HIIT has been associated with reductions in visceral fat in as little as three weeks in women with higher levels to begin with.
You Don’t Need Long Workouts — Even five intervals can still provide benefit when time is tight.
Keep HIIT and Strength Distinct — Combining both into one muddled circuit can compromise the quality of each training stimulus.
Do Your Priority First — If strength is the goal, lift first; if cardiovascular adaptation is the priority, do HIIT first.
Heavy Resistance Can Be Time-Efficient — Dr. Abbie describes a 30-minute protocol using 6–8 rep loads and short rest periods.
The Norwegian 4x4 Works Too — Longer intervals are effective, but one-minute bouts may be easier to execute consistently in midlife.