No.
Well that was a short article. Maybe I should expand a little. I'll start with what fitness is. Dictionary.com calls it the "capability of the body of distributing inhaled oxygen to muscle tissue during increased physical effort." CrossFit founder Greg Glassman defines it as "increased work capacity across broad time and modal domains" and goes into much more detail in his seminal article "What is fitness, and who is fit?" The National Strength and Conditioning Association in its pamphlet "The foundations of fitness programming", many facets of fitness are discussed, but no singular definition emerges. That said, there is a growing consensus that fitness is a multi-faceted quality, reflecting the capacity of the individual to perform physical tasks. With that thought in mind, running presents a problem or two; it adds little strength, flexibility, power or indeed much else outside of cardiovascular endurance and aerobic efficiency. Sure, there are some initial leg strength gains to be had, and the specialist may develop some raw speed. Runners will also develop, or at least maintain, low levels of coordination and balance, but nobody is seriously arguing that running is a total fitness solution.
So why bother? Well, running might not be a fitness solution, but I would contend that it is an important part of one. It is also a life skill that you never know you need until it's too late. There remain several situations you might likely find yourself in that would turn out much better if you could run; it may even save your life, or help you save someone else's. There's much more to running though, a heck of a lot more. While running alone won't make you fit, it provides opportunities and experiences that aren't otherwise available, adds to a well rounded physical fitness programme if structured well, and is a great way to escape, spend time with friends, or just enjoy the great outdoors.
There are plenty of beautiful locations in the United Kingdom that are only accessible on foot. Sure, you could walk, but then you will see much less in the time that you have available. You will also reap less of the fitness benefits, and you'll miss out on that endorphin high once you finish. Running is your gateway to this, and so much more. Running is truly an exercise that fits time alone just as much as it offers social interaction, and is pretty unique in doing so. You can run for hours without seeing another person, or set off with a group around your local track or town, or anything in between.
Physically, running lacks a full range of motion, and suffers from quite a high injury rate, but both of these can be addressed by making running a part of a programme that involves some functional movements and strength work, and also can be helped by varying the type of runs you do, and the terrain over which you run. The benefits of trail running to the ankles and lower leg muscles are quite well documented.
Running is also pretty cheap and simple to start. A pair of trainers, some shorts and a t-shirt, and you're good to go. Of course you can spend a lot of money on fancy add-ons, but a lot of it is surplus to requirements. This accessibility means it suits many people's schedules and budgets, but it also means you can do it almost anywhere, at almost any time. For what it's worth, I would suggest not just starting without a plan, which I talk about in a previous blog here, but consider following a plan, such as the Run Strong 10km Programme, which includes strength sessions, and plans out your different types of run, and even varies the terrain.
So will running make you fit? Not on its own, no, but as part of a plan, it can bey a key component, and even an enjoyable one once there is a plan, a goal and some structure, or even just as an unplanned escape from it all.
So what next? Find yourself a programme, buy some basic weights to get you started, and go from there. Dumbbells and kettlebells which you can use TH5 to save money on if you purchase using this link, are the simplest and most flexible way to start building strength. They are pretty portable, take up little space, and basic exercises are easy to learn and comparatively low risk. You can pick up some tips for various movements on my YouTube channel for free, and add them into your existing programme, if you're not yet ready to take the leap to a full, integrated programme.