Runners have their own set of rules: some are valid, but many are suspect. The November 2011 Runner’s World has an article on “Breaking the Rules“. One of the “rules” they dismiss is “Don’t Bulk Up”.
Sarcopenia – the loss of one to two percent of muscle mass per year after age 40 – is a challenge for runners. The Runner’s World article recommends a twice-weekly routine targeting both upper and lower body.
The problem with this approach is twofold. First, a workout routine of this type tends to take quite a long time: most of us find it difficult to add an hour or two of strength training every week to our normal running training. The second problem is that a program like this is not effective in building strength and may actually make matters worse.
To understand why this is true, we need to look at muscle physiology. When we exercise a muscle, we break down tissue; when we rest the muscle, the tissue repairs and we build strength. It’s important to recognize that the strengthening does not occur during exercise, but during the rest after exercise, when the tissue repair.
It takes about 24-48 hours after exercise before the tissues start to repair, which is why you should not do strength training on consecutive days. It takes about 3-5 days for the muscles to recover to the point where they were before the exercise. During the next 5 days or so they will actually build back stronger than before.
Putting all this together means that to build strength you need to allow up to ten days between exercises of any given muscle group. If you do not allow time for the secondary recovery (the anabolic phase) you will not add muscle strength, and if the interval between similar exercises is too short (the catabolic phase) you will break down muscle tissue and never repair it. This is the reason why the 7 minute workout cycles through 5 different muscle groups working out only 3 times per week: exercising every other day allows 10 days before any workout repeats.
The other important factor is the type of workout. For maximum benefit, you need to work each muscle group as hard as possible until failure. Only one such set is required, with typically 10-15 repetitions. That’s how we can keep the exercise time down to 7 minutes, or about 20 minutes per week!
For more information, see my fitness website.