I’ve long thought you don’t necessarily get good at things by just doing those things.
I mean, for example, no musician would expect to play gigs by only ever playing gigs. Things involving motor skills need a lot of practice, in particular using repetition, focussing on difficult sections etc.

Likewise in football, I don’t think you get good at the game by only playing matches. There are things in football you just don’t do enough times during a game – or even at all in some games – to provide the repetition needed to make them habitual enough to stick.
I also came to the conclusion that if you want to be as fit as you can to play football, you need to do more than play football.
That came from my experience as I ran more frequently and played football once a week. As I ran more / more intensely, football got physically easier.
I had got into running again over lockdown and settled on 10km races as something I enjoyed — if that’s the right word — and from late summer 2021 trained for a few races in succession over the winter months.
So, my weekly schedule since around late summer 2021 has been something like:
- Monday: Football (5- to 8-a-side)
- Wednesday: Running 8km to 13km, at around lactate threshold heart rate (LTHR).
- Friday: 10km training, usually intervals/repeats at target 10km race pace. This tended to be at LTHR and above.
What I found was that during weekly recreational football I tired a lot less. I ended games a lot fresher than I used to. I didn’t run any greater distance in games (I average 4.5km in 60 minutes), but I didn’t seem to hit that wall where there was no gas left in the tank.
How could I measure this?
I looked at Strava heart rate zone data for games. As a snapshot, it seemed to confirm football was easier than running for an hour.
This would be a fairly typical HR zone chart from Strava for Monday football. ‘Time’ is moving time:

But this kind of HR zone profile would be typical for a running or running training session:

It seemed to confirm that the effort required to play football felt nothing like the effort required to run at a decent pace for an hour or so.
Obviously, those are snapshots so I tried to look at the numbers over time, and downloaded my Strava data.
I wrangled the data to ID the football sessions and label them so I could compare Strava relative effort (RE) logged during runs and during football. Strava RE measures exercise by duration, intensity etc to give it a score so that different activities can be compared.
The result seems to confirm what I expected. That is, over the last year as I ran harder during running sessions, the effort recorded during football trended downward.

There are lots of potential caveats, and one I wanted to check was distance. Was I covering the same distance in my weekly football sessions?
Here’s the chart. There’s a slight decline in the session distance trend line. Some of the low ones (the lower points in October) are accounted for by not switching my watch on, for example, and one session the day after a 10km race. But there’s a clear tail-off in the effort expended too, as indicated by the points fading from red to green.

Conclusions
What I think has happened is that “being fitter” as a result of running during the rest of the week, translates to improved lactate threshold. That’s the heart rate beyond which your body ceases to successfully shunt waste products from your muscles. Once you’ve got to it, and pushed over it for a while, that’s when you feel the tank is empty.
Running at it or near it for an hour at a time pushes that threshold to higher heart rates for longer.
That kind of exercise seems to have prepared me well for an hour of football that demands nowhere near the same levels of sustained effort.
Has my football got better? I think so. But as a result of running, it could only be in terms of fitness and not being as easily fatigued. In other words, endurance at relatively high HR only enables any base technical skill that already exists that might otherwise fade with tiredness. I’ve not turned into Messi. Just a more mobile old hoofer that can go on for an hour without tiring.
Do I get out of breath? Yes, early in a game. No training prepares you for the ‘oxygen debt’ the body suffers as it tries to move from one steady state of effort to another. But once through that I find recovery is quick or barely required and I don’t get that feeling of the tank having been drained, at least over an hour.
Would this work for everyone?
Your mileage may vary. My circumstances are not everyone’s. I’m 58, and play low-level recreational football once a week. I’ve played on and off for years and this has been a way of getting fitter to play with people who are often half my age, and to leave enough recovery days during the week in between exercise. Other rec players may not have the time, desire or need to do what I do. Some might have different needs. A skinny youngster — or not so youngster — might spend their time better building muscle, for example.
And those that play at much higher levels would have pre-season training to provide roughly similar effects — an ‘aerobic base’ — but then have to sustain playing lots of matches at high intensities during the season, and to avoid injury.
But for an average rec player that wants to improve their fitness? It worked for me.