Fergus Crawley

So the mechanism at play there is mTOR is the energy pathway that allows for strength adaptation, AMPK is the energy pathway that allows for endurance adaptation.

Up until recently, so 2000s, they looked at this in more detail.

There's been a meta-analysis since.

They believe that mTOR and AMPK were switches.

So if mTOR was activated, AMPK could not be activated and vice versa.

So therefore, the interference effect means that you cannot progress in strength and endurance concurrently.

If you look back to the original study,

six hard effort lower body sessions a week, six hard effort runs a week combined together is just terrible programming.

So it created this concept of the interference effect, which effectively is cardio kills gains.

But generally speaking, it's considered to be a poor focus group to get there.

So then more recently, it's been discovered through more research that they're not on and off switches and that they're rather blunted.

To what degree, it can't be measured in a percentage, but when you are lifting and mTOR is activated, then the response that you can get from an endurance adaptation is going to be reduced for a limited period of time because that is activated.

So that's where trying to, where possible, separate these disciplines

is the best way to adapt towards specific goals.

So the best one is to lift in the morning and run in the evening?

In general terms, but only if you need to be doing two sessions a day in the first place.

And that's where working backwards from specific goals is key because most people don't need to be doing two sessions a day

to be able to make the progress towards the goals that they've got.

So there's not much room in terms of fatigue.

Not really, no.