There’s no doubt that strength training is beneficial for distance runners, but if you want to reap the maximum benefit from your time in the gym, you have to do it properly. A common mistake runners make during their strength training sessions is to lift for endurance (doing a high number of repetitions with light weight) as opposed to strength (heavier weight, fewer reps). While it seems sensible that endurance runners should lift for endurance, it’s actually the opposite. If runners want to get stronger (and not bigger) they should be lifting heavy.
The case against endurance lifting
It seems to make sense that lifting light weights for a high number of repetitions would improve the endurance capacity of your muscles, but this actually isn’t true. In fact, research has shown that doing 12 to 20 reps of an exercise does not increase endurance any more than doing six to eight reps. Considering that you’re already training your muscles for endurance during your runs and speed workouts anyway, trying to train the same system in the gym is redundant, and less useful since it’s not as sport-specific.
When you’re hitting the weight room, it’s important to keep in mind why you’re there: to get stronger. Stronger bodies are more resistant to injuries, and can also apply more force to the ground with each step. A more powerful stride means you’ll be able to run faster and you’ll be more resistant to fatigue, so you can maintain that higher capacity for longer. So while it seems counterintuitive to train the opposite energy system to the one you use when you’re running long distances, it actually has a more direct impact on your performance than lifting for endurance.
No, lifting heavy weights won’t “bulk you up”
This is one of the biggest worries runners have with regards to strength training, but here’s the good news: it’s a myth. Incidentally, doing high repetitions with moderate weights (also known as hypertrophy workouts) will add muscle mass, a.k.a. “bulk you up.” True strength training, which involves heavy weights and only four to six reps per set (and long rest between sets) will make your muscles stronger without adding mass.
Given that running is a catabolic activity (meaning it breaks down muscle), and most runners include no more than two to three gym sessions per week in their training plan, putting on any significant muscle mass would be very unlikely. Muscle gain requires at least four to five sessions of focused hypertrophy workouts with adequate rest from catabolic activities in order to see any significant changes.
Get started safely
Just like you wouldn’t jump right into doing VO2 max workouts when you’re a beginner runner, you shouldn’t go straight to the gym and try to pick up the heaviest thing you can find, either. If you’ve never done any kind of heavy lifting (or if it’s been a while), it’s important to start out lighter and work your way up to the heavy stuff to avoid injuries.
It’s also important that you perform each exercise with proper form so that you don’t hurt yourself. Of course, enlisting the help of a personal trainer or coach who can guide you through the movements is ideal, but if that’s not possible, there are plenty of tutorials online that teach you how to do basic lifts, like squats, deadlifts, single-leg squats and lunges, with proper form. Once you’re confident you can do each exercise safely, you can start to add weight and challenge yourself.