This is a very popular question. Read running magazines and you will think the answer is obvious. Well, do a little more research and the answer becomes much more fuzzy.

The first research I suggest doing for any questions of training is to look at what the elite runners do. These are the people who have gotten the most out of their training. They have figured out what is worth their time and energy and what isn't. So, what do the elite runners do? Well, very few elite runners who focus on events of 5k and up go anywhere near weight rooms. That doesn't mean they don't do strength training, though. The most popular form of strength training for elites is running hills. Repeats, circuits, easy and long runs over hills, fartleks, you name it. The bottom line is that they spend a lot of time running up and down. That's not all they do, though. Core strengthening is something that almost all of them do. Abdominal training is done by many elites. Circuit training is also popular with some, as well as body weight exercises, like pushups, pullups, step-ups, one-leg squats or lunges, one-leg hops or toe raises. Some, although they are a distinct minority, especially as their goal distance becomes longer, also lift weights.

Another form of research that I like to look through would be scientific studies. So, what do they say? Well, not a whole lot for lifting weights for distance runners. Studies have shown that lifting weights is most likely beneficial for racing distances that take less than 10 minutes to complete. What about the longer distances? Well, things change sharply. In fact, I have seen only one study that showed lifting weights is beneficial for "well trained" athletes and I found that study to be questionable. That study also said it is beneficial for the 5k but findings were inconclusive once the race distance was over 20 minutes. I have yet to see one study that found weight training to be beneficial for anything longer than that. What about athletes who are not "well trained"? Well, studies have shown that adding weight lifting on top of their current training routine does help improve performance, which makes sense. You are increasing training load. Regardless of what that training is, increasing training load will increase fitness. But there's a catch. Using that increased training load to do more running instead of lifting weights leads to much more significant performance improvements. In the end, almost all studies have found that lifting weights has no statistically significant positive effect on racing performance in events of longer than 10 minutes and some suggest that there may be a negative effect on performance. What about other forms of strength training? Well, studies have shown that running hills is one of the most beneficial forms of training that a runner can do. Circuit training, core training, and body weight exercises haven't been studied enough to offer any quality assessments.

Of course, there is one variable that I have purposely left out so far. Many people believe lifting weights is good for injury prevention. While this sounds great, for the typical biomechanically sound runner, there is simply no evidence supporting these claims. In fact, in an unscientific study of one, my injury rates have been higher when lifting weights (under the supervision of trainers and strength and conditioning coaches) than when not lifting weights. On the other hand, if you have a biomechanical inefficiency, lifting weights may make sense to correct any imbalances.

In the end, there is not a whole lot of evidence supporting the use of weight training for performance benefit. This doesn't mean it's not worth a shot. Experiment, we are all studies of one. However, as I always say, why assume you are in the minority when chances are you are in the majority? If weight training isn't working for you, move on and find something that would make better use of your limited training time and energy. If you have to decide between a few extra miles on the roads or hitting the weight room, by all means, run a few extra miles. That is where you are going to get the best performance benefit.

In closing, I would like to offer a link to a Peak Performance Online article about strength training. I have been using the exercises mentioned in this article since my college days and find them to be much more beneficial than anything I could do in the weight room.