This is an excerpt from Stronger Legs & Lower Body by Tim Bishop.
Proper Form and Technique
Throughout the exercise section of this book you will notice instructions that relate to posture, specific joint movements (such as extending, flexing, and descending), foot placement, tempo, and breathing. These aspects of strength training are often overlooked, but they have a significant impact on the effectiveness of a strength program and, more important, the risk of injury.
Posture and Joint Movements
Maintain good posture, especially in the spinal region, when you squat, lunge, or step. Keeping your back straight (not rounded), your shoulders drawn back, and your pelvis in a neutral position allow you to handle heavier resistances without compromising your spine. When you lunge or step, keep your knees at 90 degrees to prevent the knees from moving out over the toes. Keep your body weight evenly distributed throughout your feet or even slightly back toward your heels. The combination of limiting knee flexion to 90 degrees and keeping the weight distribution toward the heel takes the pressure off your patellar tendon and the knee joint itself.
Execute machine-based exercises correctly and carefully, too. Proper posture during a leg-press exercise is just as important as proper posture during a squat. Keep your back flat against the pad of the machine and drive the platform with your feet flat, keeping your weight toward the middle of your foot. Limiting the amount of flexion during a leg-extension exercise on a machine protects your tendons and joints just as keeping your knee at 90 degrees during a lunge exercise does.
Foot placement is addressed in almost every lower-body exercise in this book because where you place your feet on the floor or on the machine will functionally change the exercise. Pay close attention to the width (distance apart) of your foot placement and the direction of the toes (pointed out, in, or straight ahead). Generally speaking, widening your stance and turning your feet outward place greater stress on the inner portion of the thigh. Turning the feet inward is usually performed on machine-based exercises only, such as those on a leg-extension machine, and places a greater emphasis on the outer portion of the thigh.
Tempo refers to the pace at which you go through each movement in the exercise. How many times have you seen someone in a gym race through an exercise with his entire body rocking in order to generate enough momentum to move the weight? Racing through an exercise often compromises technique and increases the risk of injury. There are times when a faster pace is appropriate, such as when training for explosive power; however, for the most part, a slow, controlled movement is best.
An exercise has two actions or phases of movement: the concentric phase, or the shortening of the muscle (often referred to as the exertion portion of the exercise); and the eccentric phase, or the lengthening of the muscle (often referred to as the negative or resisting portion of the exercise). During a squat, for example, the eccentric phase occurs during the part of the movement when the hips, knees, and ankles are flexing and the weight is being lowered. The concentric phase occurs when the hips, knees, and ankles extend, pushing the weight back up to the starting position. The tempo is the rate at which you move during both the concentric and eccentric phases of the repetition. It's the speed of the movement.
Depending on your goals, it may be advantageous to favor a slightly quicker tempo or a slightly slower tempo. Generally, it is important to control the weight. A slow, controlled lift is usually the safest and most effective way to perform an exercise. A general rule would be to lower the weight (eccentric movement) at a pace of about 2 to 4 seconds and to lift or push the weight at a pace of about 1 to 3 seconds. The soreness you often feel from resistance training is usually the result of the negative, or eccentric, portion of the lift. While there are some lifting techniques that are ballistic in nature (for instance, power cleans) and require a very fast tempo, generally speaking, a controlled lift with good technique is best.
Proper breathing is an important part of weight training. Often people hold their breath while lifting weights, mistakenly thinking that this gives them more power. Inhaling brings oxygen into the lungs and allows it to be transported throughout the body via blood cells. Exhaling rids the body of toxins such as carbon dioxide. Proper breathing during exercise oxygenates the working muscles, supplies them with nutrient-rich blood, and prevents the buildup of the waste products.
You have probably heard that you should breathe in during the concentric (shortening) phase of the lift and breathe out during the eccentric (lengthening) phase of the lift. Breathing out during the entire eccentric phase, however, is not the most effective procedure.
The proper way to breathe during a lifting exercise is to exhale during the work (push) phase and to inhale during the recovery (rest) phase. In the leg-press exercise, for example, inhale just before you exert force with your feet on the platform. As you exert the force and push the weight of the platform, exhale.
For healthy people with no heart or blood pressure conditions, a modified version of the Valsalva maneuver is a safe and effective way to lift heavy loads. This maneuver involves holding your breath against a closed windpipe and exerting pressure. This procedure was named for Valsalva, a 17th-century physician who studied the human ear and esophagus. Let's apply the modified Valsalva maneuver to the squat exercise. Once you have the bar on your back, expand your chest with your head and neck in a neutral position. Take a deep breath down into your belly and then begin to descend with the weight. Hold your breath through the bottom of your descent and then begin to breathe out after you push through the sticking point of the lift on the ascent. The intra-abdominal pressure that is built by holding in your breath helps support your spine while holding the heavy load. Note that if you have high blood pressure or any heart conditions, you should talk with your physician before attempting any weight-training program, and you should not use the modified Valsalva method.
Read more from Stronger Legs & Lower Body by Tim Bishop.