Before I get into it, I’d like to just state that strength training benefits everyone. If I took an endurance runner and kept him/her at their same size, but got him stronger, he will in fact increase his or her endurance. Obviously you don’t want to pack on too much size, but that’s where you need to know what your end goal is.
Is Your Sport Endurance Based, or Do You Just Want to Run??
All sports training comes down to sport specificity. If your sport is endurance running, then 3/4ths of your training should revolve around that. The most optimal way to get good at any skill is by practicing it. If you are an endurance athlete, I would only include one day of resistance training, and one day of corrective work. If you are just someone who wants to be strong, but maybe eventually wants to run a marathon, I would stick with 2-3 days of training, and slowly work in increasing the mileage.
The resistance training workouts should reflect your sports needs as well. No, that doesn’t mean box jumps to get your legs strong. A common mistake people don’t realize when it comes to strength training athletes is that the work they put in the gym is to PREVENT injury more than it is to purely make them stronger. Their sport is repetitive in nature. Imbalances will form, and muscles will be neglected. In order for an athlete to perform at their peak, they need all the stability and support their joints can get, so that means focusing on strengthening neglected areas as well as strengthening the range of motion of commonly used areas.
Endurance runners over time usually have bad posture. Their ankles might tighten up, their back is rounded, their lower back is tight. All of this needs to be addressed. Have you ever had to take a break from running because your joints started acting up? Don’t ignore it, fix it!
For a marathon runner, I would focus on different lunge variations. Forward lunges, side lunges, and a lunge matrix are all good movements. In running, you spend so much time only running forward that your legs don’t learn to stabilize on lateral movements. These movements can help keep the knee stable and get rid of joint pain there.
Let’s not forget the bad posture I mentioned. Single arm rows, bent over rows, and all row variations will help strength the upper and mid back. Doing so, will help keep your torso more upright preventing that sluggish lean forward. Running also involves a lot of core. You’re running miles and miles having to stay upright. The best runners have optimal form so that the energy translated from the ground to the upper body carries all the way through. If your core gets tired after a certain mileage, you start getting energy “leaks”. In other words, instead of staying nice and tight in the core your body starts little by little moving all over the place tiring you out a lot quicker than you should be.
For specifics on good mobility, and corrective exercises, I recommend you check out my article on mobility for runners.