1. Lie on your side and brace your core muscles.
2. Raise yourself up on the side of one foot and your elbow.
3. Raise your trunk off the floor. Do not let your middle sag. Squeeze your obliques, the muscles that cover the sides of your body (photo).
4. Hold for 30 seconds, and increase the hold to two minutes as you improve. Alternatively, you can hold for 10 seconds and repeat 10 times. (The side plank can be modified by supporting your legs with your knees.)
Your knees are biomechanical wonders. Key to your knees are your quadriceps, the four large muscles in the front of your legs.
Straight Leg Raises
1. Lying flat on your back, engage your core.
2. Bend one leg up at the knee, and keep the other leg straight.
3. Still lying flat on your back, tighten the quad muscle of your straight leg, and raise it up off the floor until your thighs are parallel. Hold this position five seconds, and then lower your leg until it almost touches the floor. Be careful not to let your back sway up off the floor. Repeat 10 times. Do two sets, and switch to the other leg.
You may not even notice the muscles in the lower part of your legs—that is, until one of them is irritated or inflamed. While I have other exercises in my book that require exercise bands, you can strengthen your lower legs (and prevent muscle imbalance and shin splints) without any equipment at all. You can do these exercises in your office, at the airport, or in the kitchen while cooking.
Wall Shin Raises
1. Stand with your back and shoulders against the wall with your feet shoulder width apart and about 1 foot in front of the wall.
2. Raise your toes as high off the ground toward your body as you can with your weight on your heels.
3. Slowly lower your toes until they are almost but not quite on the floor, and then flex them up again. Repeat this 10 times. As you get better at this exercise, you can "pulse" quickly from flexing up and extending your ankle down.
Heel Step Downs
1. Stand with your feet together, and take a natural step forward.
2. As your heel strikes the floor in front of you, prevent your foot from flexing down as you transfer your weight forward.
3. Return your foot to the starting position, and repeat on the other side.
4. Perform 10 of these step downs on each side. When you have mastered this with short strides, you can increase your stride length to make the exercise more difficult.