When I was a member of Fitocracy, those who trained with particularly heavy weights, doing fewer reps, often derided this how preferred to use lighter weights and do more reps. In particular, the arguments were often over which approach was better for increasing muscle mass. So which approach is best?
When we train our muscles, what we are doing is placing them under increasing stress. As the amount of stress increases, more muscle fibres are recruited. When we’ve recruited all the fibres we have (that is, we’ve reached failure) we have a muscle that needs rest.
During this rest, which is not the break between sets but the period after your workout, two things happen. The muscle fibres you have become larger and you grow more fibres (refer to How do muscles grow? by Young sub Kwon, M.S. and Len Kravitz, Ph.D.).
So, how do you stress the fibres sufficiently to create this effect, which is called hypertrophy?
It’s simple – you train until the muscle fails. You can do that by either lifting a heavy weight a few times or a lighter weight more and then allowing your body sufficient time to rest and build the muscle.
While a muscle might look bigger while you train this isn’t actual muscle growth. The increase in size is temporary and caused by the rush of blood into the area being trained.
This is what bodybuilders call “the pump”.
The other thing to remember is that not all muscle fibres are the same.
Traditionally, muscle fibres have been grouped in two categories.
- slow twitch
- fast twitch
But it’s not quite that simple as the fast twitch muscles are further divided into two sub groups.
Slow twitch (Type 1) muscles are better adapted for endurance activities. Fast twitch fibres are more about power.
Fast twitch fibres are better considered as “fast twitch (type IIA)” and “very fast twitch (type IIB)”. This article says
Type I fibres take about 100ms to reach peak power and fatigue slowly. Type IIA fibres take about 50ms to reach their peak and Type IIB reach their peak in about 25ms.
As these fibres all contract, reach peak power and fatigue at different rates, they all fail at different times.
Implications for weight training
If your goal is to increase muscle size, you’ll want to use a combination of lighter weights and higher reps with heavier weights and fewer reps.
When I was weight training more seriously, I used a protocol called 6-20. The goal was to superset six reps at a weight where I failed and then to take a brief break (maybe 30 seconds or so) and then do the same exercise with a lower weight for 20 reps or until I failed.
When I could do six reps heavy, I increased the weight. Or, if I could do 20 reps I increased that weight.
Implications for runners
As a runner, your aim is not to increase muscle mass. However, strength is important for all athletes. And weight training can be an important way of addressing muscle imbalances that lead to injuries.
Running might seem like an endurance activity but it’s also a power sport. Thinking of sprinting, hill running, cross country or trail running. All involve more than simply putting one foot in front of the other.
Although it’s often said hill training is strength training for runners, there’s a place for weight training.
I’ve already outlined my weight training program for runners where the focus is on compound exercises that work multiple muscles at the same time, with a focus on working muscles that aren’t highly stressed in running.
For me, that means working my glutes with squats and deadlifts as well as my upper body and core.
My focus isn’t on getting bigger – the less I have to carry on a long run the better, within reason. My focus is on being a healthy runner.
But, for runners looking for some extra strength, chances are you’re already working the Type I fibres pretty hard in your longer runs. That means putting some focus on the Type IIA and IIB fibres. And that means heavier weights.
I’d stay away from particularly low rep/heavy weight sets. Aiming for six to ten reps with a challenging weight where you’re failing at the end of the set is probably a good way to go. If you train alone, as I do much of the time, you’ll need to hold back a little so you don’t get pinned under a bar and work out in a place where you can throw a weight down or drop it away from your body if you get in trouble.
Strength training is important for runners. And that means doing more than just running.
Add some strength training with weights that are challenging for six to ten reps. Focus on muscle groups that aren’t specifically trained by running. A gait analysis by a podiatrist or at a specialty running store will tell you if you’re not using particular muscles effectively or if something needs strengthening.