Really good article from Runner’s World on the importance of strength training and some tips on how to get started.

Strength Training: Basics

From fitness newbie to professional athlete, a basic strength training routine is important for getting the body you want. It’s as fundamental to a fitness regimen as the little black dress to a wardrobe or beer at a ballgame. Strength training will make you stronger, reduce body fat, reduce the chance of injuries, increase bone density, improve your appearance and give you more self-confidence. However, there are several resilient myths out there that can really slow down your progress. Here’s the lowdown:

To strength train, you have to lift weights

Not so. Any resistance exercise is part of a strength training routine, whether you’re lifting a dumbbell, doing a push-up or pulling on a rubber resistance band attached to a doorknob. Any of these exercise types will result in a “training effect” — that is, some response from your body, typically building more muscle and shedding fat. It’s your body’s way of adapting to the physical stress of resistance.

To lose weight, you need cardio; strength training is just for building muscle

Weightlifting is for building muscle and for losing fat. Think of your muscles as calorie-burning furnaces. The more muscle mass you have the more calories you burn, even while at rest. It’s true because it takes more energy for your body to maintain a pound of muscle than it does a pound of fat.

When you start a fitness routine, you might be surprised to see that your weight actually changes very little, but that you look and feel a whole lot better — and your clothes are less snug. That’s because muscle is heavier but takes up less space than fat. So don’t stress about the scale.

High repetitions done with low weight will tone me 

“Toning” is vague goal. To be more specific, you can only build or lose muscle or add or lose fat. You probably want some combination of building muscle and losing fat. If you do a lot of reps with low weight, but you could still do more at the end of the set, the weight is too light to cause the training effect you desire. You need to add weight so that you are fatigued at the end of each set. 

Consider the woman who told her trainer “I don’t want to look like that,” pointing to a beefy guy in the gym and putting down the 7.5 pound dumbbells she was holding.  If only it were so easy! The body needs to be challenged in order to change — and if you aren’t tired at the end of a set, you aren’t getting enough challenge.

If you stop working out, your muscles will turn to fat

Sorry, but you need a better excuse for picking up donuts instead of dumbbells. Muscle doesn’t turn to fat, so there’s no fear that adding more muscle will make you fatter later. If you stop working out, you will gain fat and lose muscle, true. But muscle won’t magically turn into fat.

I need to lift heavier weights each workout to get stronger and bigger

Pick up heavier weights every time you go to the gym and what you’ll get is an injury. Your body needs time to recover in order to get stronger. Give your muscles a day off between strength workouts, by doing a different kind of workout or by working a different part of your body. Then, try the same weight the next time, and only increase it if you can do more than 20 repetitions with good form. When you do increase it, add at most 10 percent more weight.