When properly performed, strength training can provide significant functional benefits and improvement in overall health and well-being including increased bone, muscle, tendon and ligament strength and toughness, improved joint function, reduced potential for injury, increased bone density, improved cardiac function and elevated good cholesterol. Training commonly uses the technique of progressively increasing the force output of the muscle through incremental increases of weight, elastic tension or other resistance, and uses a variety of exercises and types of Weight training equipment to target specific muscle groups. Strength training is primarily an anaerobic activity, although some proponents have adapted it to provide the benefits of aerobic exercise through circuit training.
Strength training differs from bodybuilding, weightlifting, powerlifting and strongman, which are sports rather than forms of exercise. However, participants in these and many other sports often use strength training as part of their training regiment.
Until the 20th century, the history of strength training was essentially a history of weight training. With the advent of modern technology, materials and knowledge, the methods that can be used for strength training have multiplied significantly.
Hippocrates explained the principle behind strength training when he wrote "that which is used develops, and that which is not used wastes away", referring to muscular hypertrophy and atrophy. Progressive resistance training dates back at least to Ancient Greece, when legend has it that wrestler Milo of Croton trained by carrying a newborn calf on his back every day until it was fully grown. Another Greek, the physician Galen, described strength training exercises using the halteres (an early form of dumbbell) in the 2nd century. Ancient Persians used the meels, which became popular during the 19th century as the Indian club, and has recently made a comeback in the form of the clubbell.
The dumbbell was joined by the barbell in the latter half of the 19th century. Early barbells had hollow globes that could be filled with sand or lead shot, but by the end of the century these were replaced by the plate-loading barbell commonly used today.
Strength training with isometric exercise was popularised by Charles Atlas from the 1930s onwards. The 1960s saw the gradual introduction of exercise machines into the still-rare strength training gyms of the time. Strength training became increasingly popular in the 1980s following the release of the bodybuilding movie Pumping Iron and the subsequent popularity of Arnold Schwarzenegger. Since the late 1990s increasing numbers of women have taken up strength training, influenced by programs like Body for Life; currently nearly one in five U.S. women engages in weight training on a regular basis.
The goal of resistance training, according to the American Sports Medicine Institute (ASMI), is to "gradually and progressively overload the musculoskeletal system so it gets stronger." Research shows that regular resistance training will strengthen and tone muscles and increase bone mass.
Strength training also requires the use of 'good form', performing the movements with the appropriate muscle group(s), and not transferring the weight to different body parts in order to move greater weight/resistance (called 'cheating'). Failure to use good form during a training set can result in injury or an inability 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.
The benefits of strength training include increased muscle, tendon and ligament strength, bone density, flexibility, tone, metabolic rate and postural support.
Individuals typically perform one to six sets per exercise, and one to three exercises per muscle group, with short breaks between each set - the specific combinations of reps, exercises, sets and break duration depends on the goals of the individual program. The duration of these breaks determines which energy system the body utilizes. Performing a series of exercises with little or no rest between them, referred to as "circuit training", will draw energy mostly from the aerobic energy system. Brief bursts of exercise, separated by breaks, are fueled by anaerobic systems, which use either phosphagens or glycolysis.
For developing endurance, gradual increases in volume and gradual decreases in intensity is the most effective program.
It has been shown that for beginners, multiple-set training offers minimal benefits over single-set training with respect to either strength gain or muscle mass increase, but for the experienced athlete multiple-set systems are required for optimal progress. However, one study shows that for leg muscles, three sets are more effective than one set.
Beginning weight-trainers are in the process of training the neurological aspects of strength, the ability of the brain to generate a rate of neuronal action potentials that will produce a muscular contraction that is close to the maximum of the muscle's potential.
|Load (% of 1RM)||80-100||70-100||60-80||40-60|
|Reps per set||1-5||1-5||8-15||25-60|
|Sets per exercise||4-7||3-5||4-8||2-4|
|Rest between sets (mins)||2-6||2-6||2-5||1-2|
|Duration (seconds per set)||5-10||4-8||20-60||80-150|
|Speed per rep (% of max)||60-100||90-100||60-90||60-80|
|Training sessions per week||3-6||3-6||5-7||8-14|
|Table reproduced from Siff, 2003|
Weights for each exercise should be chosen so that the desired number of repetitions can just be achieved.
However, performing exercises at the absolute limit of one's strength (known as one rep max lifts) is considered too risky for all but the most experienced practitioners. Moreover, most individuals wish to develop a combination of strength, endurance and muscle size. One repetition sets are not well suited to these aims. Practitioners therefore lift lighter (sub-maximal) weights, with more repetitions, to fatigue the muscle and all fibres within that muscle as required by the progressive overload principle.
Commonly, each exercise is continued to the point of momentary muscular failure. Contrary to widespread belief, this is not the point at which the individual thinks they cannot complete any more repetitions, but rather the first repetition that fails due to inadequate muscular strength. Training to failure is a controversial topic with some advocating training to failure on all sets while others believe that this will lead to overtraining, and suggest training to failure only on the last set of an exercise. Some practitioners recommend finishing a set of repetitions just before the point of failure; e.g. if you can do a maximum of 12 reps with a given weight, only perform 11. Adrenaline and other hormones may promote additional intensity by stimulating the body to lift additional weight (as well as the neuro-muscular stimulations that happen when in “fight-or-flight” mode, as the body activates more muscle fibres), so getting "psyched up" before a workout can increase the maximum weight lifted.
Weight training can be a very effective form of strength training because exercises can be chosen, and weights precisely adjusted, to safely exhaust each individual muscle group after the specific numbers of sets and repetitions that have been found to be the most effective for the individual. Other strength training exercises lack the flexibility and precision that weights offer.
These variables are important because they are all mutually conflicting, as the muscle only has so much strength and endurance, and takes time to recover due to microtrauma. Increasing one by any significant amount necessitates the decrease of the other two, eg. increasing weight means a reduction of reps, and will require more recovery time and therefore fewer workouts per week. Trying to push too much intensity, volume and frequency will result in overtraining, and eventually lead to injury and other health issues such as chronic soreness and general lethargy, illness or even acute trauma such as avulsion fractures. A high-medium-low formula can be used to avoid overtraining, with either intensity, volume, or frequency being high, one of the others being medium, and the other being low. One example of this training strategy can be found in the following chart:
|Intensity (% of 1RM)||10-40%||50-70%||80-100%|
|Volume(per muscle)||1 exercise||2 exercises||3+ exercises|
|Sets||1 set||2-3 sets||4+ sets|
|Reps||20+ reps||8-15 reps||1-6 reps|
|Session Frequency||1 p/w||2-3 p/w||4+ p/w|
A common training strategy is to set the volume and frequency the same each week (eg. training 3 times per week, with 2 sets of 12 reps each workout), and steadily increase the intensity (weight) on a weekly basis. However, to maximize progress to specific goals, individual programs may require different manipulations, such as decreasing the weight, and increase volume or frequency.
Making program alterations on a daily basis (daily undulating periodization) seems to be more efficient in eliciting strength gains than doing so every 4 weeks (linear periodization), but for beginners there are no differences between different periodization models.
For this example, the lifter has a 1 rep max of 225 lb:
|Week||Set 1||Set 2||Set 3||Set 4||Set 5||Volume Lbs.||Peak Intensity(Last Set)||% of 1 Rep Max(Last Set)|
|1||95 lb x 8reps||100 lb x 8reps||110 lb x 8reps||115 lb x 8reps||120 lb x 8reps||4,320||73%||52.5%|
|2||105 lb x 8reps||110 lb x 7reps||115 lb x 7reps||125 lb x 7reps||130 lb x 7reps||4,200||79%||57.75%|
|3||110 lb x 7reps||120 lb x 7reps||125 lb x 6reps||135 lb x 6reps||140 lb x 6reps||4,010||84%||63%|
|4||125 lb x 6reps||130 lb x 6reps||140 lb x 6reps||145 lb x 5reps||155 lb x 5reps||3,870||88%||68.25%|
|5||130 lb x 5reps||140 lb x 5reps||150 lb x 5reps||155 lb x 5reps||165 lb x 4reps||3,535||94%||73.5%|
|6||140 lb x 4reps||150 lb x 4reps||160 lb x 4reps||165 lb x 4reps||175 lb x 4reps||3,160||99%||79%|
This is an example of periodization where the volume decreases while the intensity and weight increases.
Many people take up weight training to improve their physical attractiveness. Most men can develop substantial muscles; most women lack the testosterone to do this, but they can develop a firm, "toned" (see below) physique, and they can increase their strength by the same proportion as that achieved by men (but usually from a significantly lower starting point). Ultimately an individual's genetics dictate the response to weight training stimuli to some extent.
The body's basal metabolic rate increases with increases in muscle mass, which promotes long-term fat loss and helps dieters avoid yo-yo dieting. Moreover, intense workouts elevate the metabolism for several hours following the workout, which also promotes fat loss.
Weight training also provides functional benefits. Stronger muscles improve posture, provide better support for joints, and reduce the risk of injury from everyday activities. Older people who take up weight training can prevent some of the loss of muscle tissue that normally accompanies ageing—and even regain some functional strength—and by doing so become less frail. They may be able to avoid some types of physical disability. Weight-bearing exercise also helps to prevent osteoporosis. The benefits of weight training for older people have been confirmed by studies of people who began engaging in it even in their 80s and 90s.
Strength training is the key to maintaining good flexibility. It takes your body parts through a full range of motion and if you use the right technique, you will be able to develop strength throughout an entire range of movement. The ability of the body to resist the stresses that can result from an injury can be increased by obtaining a greater amount of strength. That is true in the athletic world and it has its advantages in performing everyday activities, such as lifting or carrying objects. Strength contributes to the overall efficiency of the human body. Starting a strength training program, means you have started a new lifestyle because strength is reversible. It will decline if you do not continue to obtain a strength stimulus throughout your entire life.
Stronger muscles improve performance in a variety of sports. Sport-specific training routines are used by many competitors. These often specify that the speed of muscle contraction during weight training should be the same as that of the particular sport.
Though weight training can stimulate the cardiovascular system, many exercise physiologists, based on their observation of maximal oxygen uptake, argue that aerobics training is a better cardiovascular stimulus. Central catheter monitoring during resistance training reveals increased cardiac output, suggesting that strength training shows potential for cardiovascular exercise. However, a 2007 meta-analysis found that, though aerobic training is an effective therapy for heart failure patients, combined aerobic and strength training is ineffective.
Bodybuilding, strongman competitions and other sports are illustrations of how the basic principles and methods of strength training can be applied to achieve very different goals.
A light, balanced meal prior to the workout (usually one to two hours beforehand) ensures that adequate energy and amino acids are available for the intense bout of exercise. Water is consumed throughout the course of the workout to prevent poor performance due to dehydration. A protein shake is often consumed immediately following the workout, because both protein uptake and protein usage are increased at this time. Glucose (or another simple sugar) is often consumed as well since this quickly replenishes any glycogen lost during the exercise period. To maximise muscle protein anabolism, recovery drink should contain glucose (dextrose), protein (usually whey) hydrosylate containing mainly dipeptides and tripeptides, and leucine. Some weight trainers also take ergogenic aids such as creatine or steroids to aid muscle growth. However, the effectiveness of some products is disputed and others are potentially harmful.
The results obtained by female bodybuilders are extremely atypical: they are self-selected for their genetic ability to build muscle, perform enormous amounts of exercise, their musculature is exaggerated by very low body fat, and like many male bodybuilders their results may be enhanced by anabolic steroids. Unless a woman dedicates her life to bodybuilding, she will not achieve the same results as a professional female bodybuilder. In addition, though bodybuilding uses the same principles as strength training, it is with a goal of gaining muscle bulk. Strength trainers with different goals and programs will not gain the same mass as a female professional bodybuilder.
What muscle builders refer to as a toned physique is one that combines reasonable muscular size with moderate levels of body fat, qualities that may result from a combination of diet and exercise. High-repetition exercises indeed do cause hypertrophy of both slow-twitch and high-twitch muscle fibers, contributing to overall increased muscle bulk.
Dieting has no effect on muscle hypertrophy of any type of muscle fiber. It may however decrease the thickness of the subcutaneous fat between muscle and skin, through an overall reduction in body fat, thus making muscle striations more visible.
Younger children are at greater risk of injury than adults should they drop a weight on themselves or perform an exercise incorrectly; further, they may lack understanding of, or ignore the safety precautions around weight training equipment. Safer alternatives for children include the use of sandbags or a lightly loaded weight vest such as the Hyper Vest. As a result, supervision of minors is considered vital to ensuring the safety of any youth engaging in strength training.
This too depends on the type of strength training utilized. Because weight training generally is used for bulking, this bulking method will more than likely increase weight because of the diet involved. However, when resistance or circuit training is used, because it is not geared towards bulking, women tend to lose weight more quickly. Lean muscle requires calories to maintain itself at rest, which will help reduce fat through the Basal Metabolic Rate.
An exercise should be halted if marked or sudden pain is felt, to prevent further injury. However, not all discomfort indicates injury. Weight training exercises are brief but very intense, and many people are unaccustomed to this level of effort. The expression "no pain, no gain" refers to the discomfort expected from such vigorous effort. It does not suggest ignoring the more severe pain that comes from injury.
Discomfort can arise from other factors. Individuals who perform large numbers of repetitions, sets and exercises for each muscle group may experience lactic acid build-up in their muscles, which, contrary to popular belief, is not the cause of the harmless burning sensation in the muscles. These individuals may also experience a swelling sensation in their muscles from increased blood flow (the "pump"), which is also harmless.
Beginners are advised to build up slowly to a weight training program. Untrained individuals may have some muscles that are comparatively stronger than others. An injury can result if, in a particular exercise, the primary muscle is stronger than its stabilising muscles. Building up slowly allows muscles time to develop appropriate strengths relative to each other. This can also help to minimise delayed onset muscle soreness. A sudden start to an intense program can cause significant muscular soreness. Unexercised muscles contain cross-linkages that are torn during intense exercise.
Weight trainers commonly spend 5 to 20 minutes warming up their muscles with aerobic exercise before starting a workout. They also stretch muscles after they have been exercised. The exercises are performed at a steady pace, taking at least two to four seconds to lift and lower the weight, to avoid jerks that can damage muscles and joints.
Exercises where a barbell is held above the body, such as the squat or the bench press, are normally performed inside a squat cage, which can catch the bar, or in the presence of one or more spotters, who can safely re-rack the barbell at the end of the set if the weight trainer is unable to do so.
Anyone beginning an intensive physical training program is typically advised to consult a physician, because of possible undetected heart or other conditions for which such activity is contraindicated.
There have been mixed reviews regarding the use of weightlifting belts and other devices, such as lifting straps. Critics claim that they allow the lifter to use more weight than they 'should'. Using a belt is more controversial as it does not prepare people for real situations, as they do not normally wear lifting belts when performing real-life tasks. This can lead to inadequate inter-abdominal pressure and torso/lower back stabilization ability. Some criticize that the gripping muscles in the forearms receive less benefit from the deadlift when using straps. This is not a concern to people who do other exercises for forearm development, or who are not concerned with forearm development. Strap-like implements are commonly used in real-life deadlifting situations, and in many cases weights are levered against the body or sandwiched between the arms, so that not as much gripping strength is used anyway. One less abrasive alternative to deadlifting with straps would be to lift wearing wrist weights, as they would add to the weight without further stressing the grip.
Weight training is primarily an isotonic form of exercise, because the muscles are used to push or pull weighted objects. Any object can be used for weight training, but dumbbells, barbells and other specialised equipment are normally used because they can be adjusted to specific weights, and are easily gripped. However, some exercises are not strictly isotonic because the force on the muscle varies as the joint moves through its range of motion, even though the force of the exercise remains constant.
Some forms of weight training use isometric contractions to further stress the muscles after or during a period of isotonic exercise. In this case the muscles flex and hold a stationary position, and no movement of a load takes place.
Another form of training that often uses weights has a different goal. Plyometric exercises exploit the stretch-shortening cycle of muscles to enhance the myotatic (stretch) reflex. This involves rapid alternation of lengthening and shortening of muscle fibers against a 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 or the body with a weight vest that allows movement such as the Hyper Vest. Plyometrics is used to develop explosive speed, and focuses on power instead of maximal strength, and may be used to improve the effectiveness of a boxer's punch, for example, or to increase the vertical jumping ability of a basketball player.
An isolation exercise is one where the movement is restricted to one joint. For example, the leg extension is an isolation exercise for the quadriceps. The other muscle groups are only minimally involved—they just help the individual maintain a stable posture—and movement occurs only around the knee joint. Other examples are the straight-legged deadlift (hip extension) and the dumbbell/barbell curl (elbow flexion).
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.
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 powerlifter would focus on the specific compound exercises that are performed at powerlifting 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.
There are a number of exercise machines and other equipment that are commonly found in strength training facilities.
Free weights include dumbbells, barbells and other objects. Unlike some exercise machines, they do not constrain users to specific, fixed movements, and require more stabilization skills. It is often argued that free weight exercises are superior for precisely this reason. As exercise machines can prevent 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. Many serious athletes, bodybuilders and fitness enthusiasts prefer to train with free weights and compound exercises.
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.
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 a good posture.
Except in the extremes, a muscle will fire fibres of both the aerobic or anaerobic types on any given exercise, in varying ratio depending on the load on the intensity of the contraction. This is known as the energy system continuum. At higher loads, the muscle will recruit all muscle fibres possible, both anaerobic ("fast-twitch") and aerobic ("slow-twitch"), in order to generate the most force. However, at maximum load, the anaerobic processes contract so forcefully that the aerobic fibers are completely shut out, and all work is done by the anaerobic processes. Because the anaerobic muscle fibre uses its fuel faster than the blood and intracellular restorative cycles can resupply it, the maximum number of repetitions is limited. In the aerobic regime, the blood and intracellular processes can maintain a supply of fuel and oxygen, and continual repetition of the motion will not cause the muscle to fail.
Circuit weight training is a form of exercise that uses a number of weight training exercise sets separated by short intervals. The cardiovascular effort to recover from each set serves a function similar to an aerobic exercise, but this is not the same as saying that a weight training set is itself an aerobic process.
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 most common exercises for these muscle groups are listed below. (Videos of these and other exercises are available at exrx.net and from the University of Wisconsin) The sequence shown below is one possible way to order the exercises. The large muscles of the lower body are normally trained before the smaller muscles of the upper body, because these first exercises require more mental and physical energy. 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. The stabilising muscles in the waist should be trained last.
Wrist straps: Wrist straps (lifting straps) are sometimes used to assist in gripping very heavy weights. They are particularly useful for the deadlift. Some lifters avoid using wrist straps in order to develop their grip strength, just as some go further by using thick bars. Wrist straps can allow a lifter initially to use more weight than they might be able to handle safely for an entire set, as unlike simply holding a weight, if it is dropped then the lifter must descend with it or be pulled down. Straps place stress on the bones of the wrist which can be potentially harmful if excessive.