Weight training is a common type of strength training for developing the strength and size of skeletal muscles. It uses the force of gravity (in the form of weighted bars, dumbbells or weight stacks) to oppose the force generated by muscle through concentric or eccentric contraction. Weight training uses a variety of specialized equipment to target specific muscle groups and types of movement.
Weight training differs from bodybuilding, weightlifting, power lifting and strongman, which are sports rather than forms of exercise. Weight training, however, is often part of the athlete's training regimen.
Weight training vs. Strength Training
Strength training is an inclusive term for all types of exercise devoted towards increasing muscular strength and size (as opposed to muscular endurance, associated with aerobic exercise, or flexibility, associated with stretching exercise like yoga or pilates, though endurance and flexibility can improve as a byproduct of training). Weight training is one type of strength training and the most common, seen by all but specialists as synonymous with strength training. The difference between weight training and other types of strength training is how the
opposition to muscular contraction is generated. Resistance training uses elastic or hydraulic forces to oppose muscular contraction and isometric exercise uses structural or intramuscular forces (e.g. doorways or the body's own muscles).
Strength training
The basic principles of weight training are essentially identical to those of strength training, and involve a manipulation of the number of repetitions (reps), sets, tempo, exercise types and weight moved to cause desired increases in strength, endurance, size or shape. The specific combinations of reps, sets, exercises and weight depends upon the aims of the individual performing the exercise; sets with fewer reps can be performed with heavier weights, but have a reduced impact on endurance.
In addition to the basic principles of strength training, a further consideration added by weight training is the equipment used. Types of equipment include barbells, dumbbells, pulleys and stacks in the form of weight machines or the bodies own weight in the case of chin-ups and push-ups. Different types of weights will give different types of resistance, and often the same absolute weight can have different relative weights depending on the type of equipment used. For example, lifting 10 kilograms using a dumbbell requires significantly more force than moving 10 kilograms on a weight stack due to the use of pulleys.
Weight training also requires the use of 'good form', performing the movements with the appropriate muscle group, and not transferring the weight to different body parts in order to move greater weight (called 'cheating'). Failure to use good form during a training set can result in injury or a failure to meet training goals since the desired muscle group is not challenged sufficiently, the threshold of overload is never reached and the muscle does not gain in strength.
Weight training can be a very effective form of strength training because exercises, weights, sets and reps can be precisely manipulated to challenge individual muscle groups in a way found to be the most effective for the individual. Other strength training exercises or equipment may lack the flexibility and precision that weights offer, and often cannot be safely taken to the point of momentary muscular failure.
Isotonic and plyometric exercises
These terms combine the prefix "iso" (meaning "same") with "tonic" (strength) and "plio" (more) with "metric" (distance). In "isotonic" exercises the force applied to the muscle does not change (while the length of the muscle decreases or increases) while in "plyometric" exercises the length of the muscle stretches and contracts rapidly to increases the power output of a muscle.
Weight training is primarily an isotonic form of exercise, as the force produced by the muscle to push or pull weighted objects should not change (though in practice the force produced does decrease as muscles fatigue). Any object can be used for weight training, but dumbbells, barbells and other specialized equipment are normally used because they can be adjusted to specific weights and are easily gripped. Many exercises are not strictly isotonic because the force on the muscle varies as the joint moves through its range of motion. Movements can become easier or harder depending on the angle of muscular force relative to gravity - for example, a standard biceps curl becomes easier as the hand approaches the shoulder as more of the load is taken by the structure of the elbow. Certain machines such as the Nautilus involve special adaptations to keep resistance constant irrespective of the joint angle.
Plyometric exercises exploits the stretch-shortening cycle of muscles to enhance the myotatic (stretch) reflex. This involves rapid alternation of lengthening and shortening of muscle fibers against resistance. The resistance involved is often a weighted object such as a medicine ball, but can also be the body itself as in jumping exercises. Plyometrics is used to develop explosive speed, and focuses on maximal power instead of maximal strength by compressing the force of muscular contraction into as short a period as possible, and may be used to improve the effectiveness of a boxer's punch, or to increase the vertical jumping ability of a basketball player.
Isolation Exercises vs. Compound Exercises
The leg extension is an isolation exercise. An isolation exercise is one where the movement is restricted to one joint and one muscle group. For example, the leg extension is an isolation exercise for the quadriceps. Specialized types of equipment are used to ensure that other muscle groups are only minimally involved—they just help the individual maintain a stable posture—and movement occurs only around the knee joint. Most isolation exercises involve machines rather than dumbbells and barbells (free weights), though free weights can be used when combined with special positions and joint bracing.
Compound exercises work several muscle groups at once, and include movement around two or more joints. For example, in the leg press movement occurs around the hip, knee and ankle joints. This exercise is primarily used to develop the quadriceps, but it also involves the hamstrings, glutes and calves. Compound exercises are generally similar to the ways that people naturally push, pull and lift objects, whereas isolation exercises often feel a little unnatural. Compound exercises generally involve dumbbells and barbells (free weights), involving more muscles to stabilize the body and joints as well as move the weight.
The leg press is a compound exercise. Each type of exercise has its uses. Compound exercises build the basic strength that is needed to perform everyday pushing, pulling and lifting activities. Isolation exercises are useful for "rounding out" a routine, by directly exercising muscle groups that cannot be fully exercised in the compound exercises.
The type of exercise performed also depends on the individual's goals. Those who seek to increase their performance in sports would focus mostly on compound exercises, with isolation exercises being used to strengthen just those muscles that are holding the athlete back. Similarly, a power lifter would focus on the specific compound exercises that are performed at power lifting competitions. However, those who seek to improve the look of their body without necessarily maximizing their strength gains (including bodybuilders) would put more of an emphasis on isolation exercises. Both types of athletes, however, generally make use of both compound and isolation exercises.
Free weights vs. Weight Machines
Swiss balls allow a wider range of free weight exercises to be performed. They
are also known as exercise balls, fitness balls, gym balls, sports balls, therapy
balls or body balls. They are sometimes confused with medicine balls. Free
weights are dumbbells, barbells, and kettle bells. Unlike weight machines, they
do not constrain users to specific, fixed movements, and therefore require more
effort from the individual's stabilizer muscles. It is often argued that free weight
exercises are superior for precisely this reason.
As weight machines can go some way toward preventing poor form, they are somewhat safer than free weights for novice trainees. Moreover, since users need not concentrate so much on maintaining good form, they can focus more on the effort they are putting into the exercise. However, most athletes, bodybuilders and serious fitness enthusiasts prefer to use compound free weight exercises to gain functional strength.
Some free weight exercises can be performed while sitting or lying on a Swiss ball. This makes it more difficult to maintain good form, which helps to exercise the deep torso muscles that are important for maintaining posture.
There are a number of weight machines that are commonly found in neighborhood gyms. The Smith machine is a barbell that is constrained to move only vertically upwards and downwards. The cable machine consists of two weight stacks separated by 2.5 meters, with cables running through adjustable pulleys (that can be fixed at any height) to various types of handles. There are also exercise-specific weight machines such as the leg press. A multi-gym includes a variety of exercise-specific mechanisms in one apparatus.
One limitation of many free weight exercises and exercise machines is that the muscle is working maximally against gravity during only a small portion of the lift. Some exercise-specific machines feature an oval cam (first introduced by Nautilus) which varies the resistance so that the resistance and the muscle force required, remains constant throughout the full range of motion of the exercise.
Exercises for specific muscle groups
The back extension should be left to the end of the workout, because in other exercises the lower back muscles are used to keep the back straight. This is not possible if the muscles have already been exercised and exhausted. Weight trainers commonly divide the body's individual muscles into ten major muscle groups. These do not include the hip, neck and forearm muscles, which are rarely trained in isolation. The large muscles of the lower body are normally trained before the smaller muscles of the upper body, because these first exercises require more physical and mental effort. The core muscles of the torso are trained before the shoulder and arm muscles that assist them. Exercises often alternate between "pushing" and "pulling" movements to allow their specific supporting muscles time to recover.
Comparison to other types of strength training
The benefits of weight training overall are comparable to most other types of strength training - increased muscle, tendon and ligament strength, bone density, flexibility, tone, metabolic rate and postural support. There are benefits and limitations to weight training as compared to other types of strength training.
Weight training vs. Resistance Training
Resistance training involves the use of elastic or hydraulic resistance to contraction rather than gravity. Weight training provides the majority of the resistance at the beginning, initiation joint angle of the movement, when the muscle must overcome the inertia of the weight's mass. After this point the overall resistance alters depending on the angle of the joint. In comparison, hydraulic resistance provides a fixed amount of resistance throughout the range of motion, depending on the speed of the movement. Elastic resistance provides the greatest resistance at the end of the motion, when the elastic element is stretched to the greatest extent.
Weight Training vs. Isometric Training
Isometric exercise provides a fixed amount of resistance based on the force output of the muscle. This strengthens the muscle at the specific joint angle at which the isometric exercise occurs, with some lesser gains in strength also occurring at proximal joint angles. In comparison, weight training strengthens the muscle throughout the range of motion the joint is trained in, causing an increase in physical strength from the initiating through to terminating joint angle.
Weight training & Bodybuilding
Although weight training is similar to bodybuilding, they have different objectives. Bodybuilders compete in bodybuilding competitions; they train to maximize their muscular size and develop extremely low levels of body fat. In contrast, most weight trainers train to improve their strength and anaerobic endurance while not giving special attention to reducing body fat below normal. Weight trainers tend to focus on compound exercises to build basic strength, whereas bodybuilders often use isolation exercises to visually separate their muscles, and to improve muscular symmetry.
However, the bodybuilding community has been the source of many of weight training's principles, techniques, vocabulary, and customs. Weight training does allow tremendous flexibility in exercises and weights which can allow bodybuilders to target specific muscles and muscle groups, as well as attain specific goals.