I, like so many of you reading this, am a runner.
I run. Sometimes for fun, sometimes competing, always for good health and in my case for weight maintenance.
When I started running it was after a period of being sedentary in my work and home life. My diet wasn't great but I wasn't a walking advert for shopping at Iceland either. Running had the immediate effect of helping me lose weight. My diet didn't change but the running created a calorie deficit and I started to lose weight. Slowly at first and then progressively quicker. The same thing happened with my running too. I started slowly and injury prone, but I got progressively quicker and stronger.
Running, like all other forms of exercise, places stress on the body.
And the body is a clever thing.
When placed under repeated stress the body adapts to better deal with that stress. It's two principles known as overload and adaptation. The body gets placed under more stress than it's used to (overload) and it changes to meet the new needs (adaptation).
This kept me in good check for years. I kept the weight off and got better and more efficient at running. I assumed that I would continue to improve if I continued to run.
But here is the catch. The overload that you place the body under needs to be progressively increased. This is what causes the body to continually adapt.
It's what sees performance continue to improve, and other goals to be reached too, be they fat reduction, muscle increase, PB's etc. I found that my running performance had levelled out. I had reached a plateau and the benefits had stopped coming. My body had adapted to the stress and done no more. After all why would it, like I said, the body is a clever thing.
So after years of running I found myself in the gym. Faced with machines and weights that I hadn't seen in years, because as a runner I didn't think I needed them.
I was wrong.
Running is a full body exercise. When you've run as far and as fast as you can, you need to change your training to continue to adapt so that your performance can improve further. Cross train to reduce the stress on your knees and use compound weight exercises to build strength. Squats and lunges incorporate all the running muscles and more importantly the muscles used to support these to allow them to do their job longer and better.
Running uses the quads and hamstrings as well as calf muscles, but to keep you upright and your form good, the core muscles, hip flexors and glutes are engaged and training these using resistance techniques will see an improvement in running form and efficiency.
You don't need a gym membership. Many of us run because its (relatively) cheap. Squats and lunges can be done at home using body weight as resistance, results come within weeks, not months and unlike running the performance is more visible and quickly achieved.
It may well be that to improve your running, you need to stop running so much and grab some weights. It might just be worth it.....