One of the best ways to reduce your risk of injury as a runner is to strength train, which has been shown to reduce the risk of developing an injury during sport by a third and the risk of an overuse injury by half (1). Strength training, when combined with power training, can also can also improve VO2 max and improve running economy by 4% (2,3,5) (which can translate into faster times). Running economy and VO2 max are considered to be the most important determining factors in running performance (2), so something that significantly improves both, I feel, is to be taken seriously!
It is a commonly held belief that strength and power training for runners and endurance athletes should be low load, high rep training as this is thought of as ‘strength endurance’. However, a number of recent studies have demonstrated that actually the act of running itself is an endurance exercise, and runners benefit more from heavier and more explosive strength training (2,3,5).
The proposed mechanisms by which this may happen are outlined in the Beattie study (2). A brief outline, from what I understood from the study, is as follows:
The paper includes the exact program these runners underwent. If you don’t want to read it, basically, the program consisted of heavy back squats; deadlifts; RDLs; step ups; and lunges; as well as explosive power training including jump squats with 20% 1RM load; drop/depth jumps (drop down from a height then immediately jump as high as possible); and fast continuous jumps.
It was interesting to note that in this study, and seemingly has been a finding in others before it, despite doing 40 weeks of heavy strength training, these elite runners were able to build strength by 25%, but there was NO muscle hypertrophy (meaning they did not gain ANY muscle). I was very very surprised by this. I have definitely had clients and friends who have taken up a more cardio dominant type of exercise (for example, swimming) and experienced hypertrophy, so I read further to find out how this may have been the case.
My research found another study that indicated aerobic exercise can induce hypertrophy (4). This was, however, in untrained individuals to who then took up aerobic exercising 5 days a week. Untrained individuals are quite different to highly trained individuals in terms of their response to exercise - it is much easier to gain muscle for people who have no significant recent training history. So that could explain why taking up swimming, for example, when you aren’t normally a swimmer may ‘beef up’ your upper body; whereas an endurance runner doing 5+ hours running a week and has been for years is unlikely to create any significant muscle mass gain.
What does all this mean? If you’re a runner and you’re interested in strength training, but worried about getting big muscles from it which may hinder performance, its unlikely to happen if you’re quite a serious endurance runner. Of course, everyone responds differently to exercise and different training stimuli, so it makes sense if you are considering taking up strength training and you don’t want to build muscle, you might monitor this using a body composition scan periodically.
I also looked at this from another perspective, thinking about my very enthusiastic exercising friends who are aiming to build muscle whilst simultaneously doing loads of cardio. I wonder where the limit exists for being able to do a substantial amount of cardio and still hope to build muscle. There must be a point at which both are possible, but it obviously depends on the type of weight training; type and duration of cardio; training history; and individual genetics, etc. But it is something to consider for yourself, or if you’re a trainer a point to consider with your clients, as to whether you may be accidentally getting no where by training too much of two conflicting exercise types. It does not appear that high intensity, short bouts of cardio exercise have the same dampening effect on hypertrophy (though I’m sure if you did ENOUGH of it then it could).
Interested? If you haven’t done strength training before, I strongly recommend finding a strength and conditioning coach, personal trainer, exercise physiologist or physiotherapist with adequate background in strength training to help you to get started safely.