Cardio vs. Strength

Its long been believed that cardio burns more calories than strength training does...

However.. This is NOT true.

Doing 30 minutes of strength will burn as many calories as running a 6-minute-mile  for the same amount of time

And a bonus for lifting some weights... your muscles that you worked will continue to burn more calories after you leave the gym.
With running, there is no residual calorie burn... once the work out is done.. its done.

Building muscles is beneficial for more reasons than just calorie burn though..

Women lose about 5lbs of muscle every year - strength training can help you to retain muscle, or slow loss instead!

Muscles have a higher resting metabolic rate than fat does... so build up you muscles and you will speed up your metabolism

Runners who add strength training exercises into their regime tend to do better on runs - why?

Because the strength in their muscles helps to carry them through the run

So you should add 1-2 days of strength training to your program!

If you have the time, do it before you run - then you will be using energy reserves during your run (because you already used blood glucose supply to do the strength)

-Try and move the weights, or do the exercises really slowly - this will increase the amount of muscle activation during the activity.