Strength training

Many people take up strength training to improve their physical attractiveness. There is evidence that a body type consisting of broad shoulders and a narrow waist, attainable through strength training, is the most physically attractive male attribute according to women participating in the research.[8] Most men can develop substantial muscles; most women lack the testosterone to do it, 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). An individual's genetic make-up dictates the response to weight training stimuli to a significant extent. Training can not exceed a muscle's intrinsic genetically determined qualities, though polymorphic expression does occur e.g., myosin-heavy chains.[9]

Studies also show that people are able to tell the strength of men based on photos of their bodies and faces, and that physical appearance indicates cues of strengths that are often linked to a man's physical formidability and, therefore, his attractiveness.[10] This is aligned with studies that reveal those who undergo strength training attain more self-esteem and body cathexis when compared to individuals who do not undergo training or exercise.[11] In addition, people who undergo strength training tend to have a more favorable body image even than those who also engage in regular physical activities such as walking and running.[12] More women are also increasingly revealed to be dissatisfied with their body today than those surveyed in 1984 and they often turn to exercise such as strength training to improve their body shape.[13]

Workouts elevate metabolism for up to 14 hours following 45 minutes of vigorous exercise.[14][15]

Strength 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 aging—and even regain some functional strength—and by doing so become less frail.[16] They may be able to avoid some types of physical disability. Weight-bearing exercise also helps to prevent osteoporosis and to improve bone strength in those with osteoporosis.[17] 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.

Though strength 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.[18]

Strength training may be important to metabolic and cardiovascular health. Recent evidence suggests that resistance training may reduce metabolic and cardiovascular disease risk. Overweight individuals with high strength fitness exhibit metabolic/cardiovascular risk profiles similar to normal-weight, fit individuals rather than overweight unfit individuals.[19]

For many people in rehabilitation or with an acquired disability, such as following stroke or orthopaedic surgery, strength training for weak muscles is a key factor to optimise recovery.[20] For people with such a health condition, their strength training is likely to need to be designed by an appropriate health professional, such as a physiotherapist or an occupational therapist.

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.[21]

One side effect of intense exercise is increased levels of dopamine, serotonin, and norepinephrine, which can help to improve mood and counter feelings of depression (dopamine and serotonin were not found to be increased by resistance training).[22][23]

Developing research has demonstrated that many of the benefits of exercise are mediated through the role of skeletal muscle as an endocrine organ. That is, contracting muscles release multiple substances known as myokines which promote the growth of new tissue, tissue repair, and various anti-inflammatory functions, which in turn reduce the risk of developing various inflammatory diseases.[24]

Strength training has a variety of terms used to describe parameters of strength training:

• Exercise – different movements which involve rotating joints in specific patterns to challenge muscles in different ways.
• Form – each exercise has a specific form, a topography of movement designed to maximize safety and muscle strength gains.
• Rep – short for repetition, a rep is a single cycle of lifting and lowering a weight in a controlled manner, moving through the form of the exercise.
• Set – a set consists of several repetitions performed one after another with no break between them with the number of reps per set and sets per exercise depending on the goal of the individual. The number of repetitions one can perform at a certain weight is called the Rep Maximum (RM). For example, if one could perform ten reps at 75 lb, then that weight would be their 10RM. 1RM is therefore the maximum weight that someone can lift in a given exercise—i.e. a weight that they can only lift once without a break.
• Tempo – the speed with which an exercise is performed; the tempo of a movement has implications for the weight that can be moved and the effects on the muscle.

For developing endurance, gradual increases in volume and gradual decreases in intensity is the most effective program.[27][28] Sets of thirteen to twenty repetitions develop anaerobic endurance, with some increases to muscle size and limited impact on strength.[29]

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.[30][29][31][32] However, one study shows that for leg muscles, three sets are more effective than one set.[33]

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.

Weights for each exercise should be chosen so that the desired number of repetitions can just be achieved.

The basic method of weight training uses the principle of progressive overload, in which the muscles are overloaded by attempting to lift at least as much weight as they are capable. They respond by growing larger and stronger.[35] This procedure is repeated with progressively heavier weights as the practitioner gains strength and endurance.

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.[36] Some practitioners recommend finishing a set of repetitions just before reaching a personal maximum at a given time. 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.

Split training involves working no more than three muscle groups or body parts per day, instead spreading the training of specific body parts throughout a training cycle of several days. It is commonly used by more advanced practitioners due to the logistics involved in training all muscle groups maximally. Training all the muscles in the body individually through their full range of motion in a single day is generally not considered possible due to caloric and time constraints. Split training involves fully exhausting individual muscle groups during a workout, then allowing several days for the muscle to fully recover. Muscles are worked roughly twice per week and allowed roughly 72 hours to recover. Recovery of certain muscle groups is usually achieved on days while training other groups, i.e. a 7-day week can consist of a practitioner training trapezius, side shoulders and upper shoulders to exhaustion on one day, the following day the arms to exhaustion, the day after that the rear, front shoulders and back, the day after that the chest. In this way all mentioned muscle groups are allowed the necessary recovery.[37]

Perhaps the most common form of training split in recent decades is the body-part split (sometimes known as "bodybuilder split" or "bro split"), which became popular due to being used in professional bodybuilding, and is discussed in a number of sources dedicated to physical training, such as Bodybuilding.com, T-Nation, and Muscle & Strength.[38][39][40] This kind of split is structured so that the body is divided up in what are considered the major muscle groups, i.e. chest, back, legs, shoulders, and arms (biceps and triceps), each part is then trained to exhaustion once a week on a dedicated day. Optionally, the biceps can be trained along with the back, due to the fact that they are both involved in pulling movements; conversely, the triceps can be trained along with the chest of the shoulders, as all these muscles are involved in pushing movements. Abdominal work can be spread out over multiple sessions or concentrated on just one day.

Despite the popularity of body-part splits, recent evidence suggests that multiple training sessions for the same muscle group over the course of a week are a more effective training strategy. One recent meta-analysis of experimental trials on resistance training found out that, when total training volume is equated, "frequencies of training twice a week promote superior hypertrophic outcomes to once a week".[41]

Three important variables of strength training are intensity, volume, and frequency. Intensity refers to the amount of work required to achieve the activity and is proportional to the mass of the weights being lifted. Volume refers to the number of muscles worked, exercises, sets, and reps during a single session. Frequency refers to how many training sessions are performed per week.

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, e.g. 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:

A common training strategy is to set the volume and frequency the same each week (e.g. 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.[42]

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),[43] but for beginners there are no differences between different periodization models.[44]

There are many complicated definitions for periodization, but the term simply means the division of the overall training program into periods which accomplish different goals.

Periodization is the modulating of volume, intensity, and frequency over time, to both stimulate gains and allow recovery.

In some programs for example; volume is decreased during a training cycle while intensity is increased. In this template, a lifter would begin a training cycle with a higher rep range than they will finish with.

For this example, the lifter has a 1 rep max of 225 lb:

This is an example of periodization where the number of repetitions decreases while the weight increases.

There are many methods of strength training. Examples include weight training, circuit training, isometric exercise, gymnastics, plyometrics, Parkour, yoga, Pilates, Super Slow.

Strength training may be done with minimal or no equipment, for instance bodyweight exercises. Equipment used for strength training includes barbells and dumbbells, weight machines and other exercise machines, weighted clothing, resistance bands, gymnastics apparatus, Swiss balls, wobble boards, indian clubs, pneumatic exercise equipment, hydraulic exercise equipment.

Strength training exercise is primarily anaerobic.[45] Even while training at a lower intensity (training loads of ~20-RM), anaerobic glycolysis is still the major source of power, although aerobic metabolism makes a small contribution.[46] Weight training is commonly perceived as anaerobic exercise, because one of the more common goals is to increase strength by lifting heavy weights. Other goals such as rehabilitation, weight loss, body shaping, and bodybuilding often use lower weights, adding aerobic character to the exercise.

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.[32] 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.[47] 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.

A back extension

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.

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 stabilizing muscles in the waist should be trained last.

A number of techniques have been developed to make weight training exercises more intense, and thereby potentially increase the rate of progress. Many weight lifters use these techniques to bring themselves past a plateau, a duration where a weightlifter may be unable to do more lifting repetitions, sets, or use higher weight resistance.

A drop set is an easy method of strength training where you perform a set of any exercise to failure or right before failure, and then reduce the weight and continue to lift for more repetitions with the decreased weight.

Pyramid sets are weight training sets in which the progression is from lighter weights with a greater number of repetitions in the first set, to heavier weights with fewer repetitions in subsequent sets.

A reverse pyramid is the opposite in which the heavier weights are used at the beginning and progressively lightened.

Burnouts combine pyramids and drop sets, working up to higher weights with low reps and then back down to lower weights and high reps. There are a few different ways one could perform burnout sets but the main idea is to perform an exercise until failure. You should start with a weight that is 75% of the amount of the maximum amount of weight you can lift for 1 rep. Once you've performed the exercise to exhaustion, reduce the weight and perform another set until failure, which will usually consist of much fewer repetitions. Burnout sets sound very similar to supersets but there are differences in the results they produce. Supersets help increase muscle mass, but are more efficient for producing muscle definition and shape. Burnout sets help increase muscle growth because of the buildup of lactic acid in the muscle when it's forced to the point of failure.

The diminishing set method is where a weight is chosen that can be lifted for 20 reps in one set, and then 70 repetitions are performed in as few sets as possible.[48]^:17

The rest-pause training method takes one whole set and breaks it down into a few mini sets. There are two different goals that are associated with rest-pause training, including both hypertrophy and strength. To increase hypertrophy, an athlete typically performs a set at a comfortable weight for 6 to 10 reps and then sets the weight down. Next, they would take 15 seconds' worth of deep breaths, pick the weight back up, and lift to failure. The last step can be repeated any number of times after this, but it is commonly done twice. In order to increase strength using rest-pause method, most people choose a weight that is 85–95% of their one rep max. They then perform 1 rep with this weight, followed by a longer 30- to 45-second break, and repeat this process several times.[49]

The Giant set, is a form of training that targets one muscle group (e.g. the triceps) with four separate exercises performed in quick succession, often to failure and sometimes with the reduction of weight halfway through a set once muscle fatigue sets in. This form of intense training 'shocks' the muscles and as such, is usually performed by experienced trainers and should be used infrequently.[50]

Supersets

Supersets combine two or more exercises with similar motions to maximize the amount of work of an individual muscle or group of muscles.[51] The exercises are performed with no rest period in between the exercises. The two main types of supersets are opposing muscle group supersets and same muscle group supersets. An example would be doing bench press, which predominantly works the pectoralis and triceps muscles, and then moving to an exercise that works just the triceps such as the triceps extension or the pushdown.

Push-pull supersets

Push-pull supersets are similar to regular supersets, but exercises are chosen which work opposing muscle groups. This is especially popular when applied to arm exercises, for example by combining biceps curls with the triceps pushdown. Other examples include the shoulder press and lat pulldown combination, and the bench press and wide grip row combination. A calisthenic example is alternating between pull-ups and dips.

Pre-exhaustion

Pre-exhaustion combines an isolation exercise with a compound exercise for the same muscle group. The isolation exercise first exhausts the muscle group, and then the compound exercise uses the muscle group's supporting muscles to push it further than would otherwise be possible. For example, the triceps muscles normally help the pectorals perform their function. But in the "bench press" the weaker triceps often fails first, which limits the impact on the pectorals. By preceding the bench press with the pec fly, the pectorals can be pre-exhausted so that both muscles fail at the same time, and both benefit equally from the exercise.

Breakdowns

Breakdowns were developed by Frederick Hatfield and Mike Quinn to work the different types of muscle fibers for maximum stimulation. Three different exercises that work the same muscle group are selected, and used for a superset. The first exercise uses a heavy weight (~85% of 1 rep max) for around five reps, the second a medium weight (~70% of 1 rep max) for around twelve reps, and finally the third exercise is performed with a light weight (~50% of 1 rep max) for twenty to thirty reps, or even lighter (~40% of 1 rep max) for forty or more reps. (Going to failure is discouraged.) The entire superset is performed three times.[48]^:16–17

Forced reps

Forced reps occur after momentary muscular failure. An assistant provides just enough help to get the weight trainer past the sticking point of the exercise, and allow further repetitions to be completed. Weight trainers often do this when they are spotting their exercise partner. With some exercises forced reps can be done without a training partner. For example, with one-arm biceps curls the other arm can be used to assist the arm that is being trained.

Cheat reps

Cheating is a deliberate compromise of form to maximize reps. Cheating has the advantage that it can be done without a training partner, but compromises safety. A typical example of cheat reps occurs during biceps curls when, beginning with the load at the waist, the exerciser swings the barbell or dumbbell forward and up during the concentric phase utilizing momentum to assist their bicep muscles in moving the load to a shortened muscle position. Momentum assistance during the concentric phase allows them to move greater loads during the more difficult concentric phase. The objective can be to position greater loads of resistance to the biceps in preparation of performing the eccentric phase than the more difficult concentric phase would otherwise allow. Replacing a typical function of a training partner with a solo exerciser performing cheat reps facilitates forced reps or negative reps when training alone.

Weight stripping a.k.a. Number Setting

Weight stripping is a technique used after failure with a normal resistance in certain exercises, particularly with easily adjustable machines, whereby the weight trainer or a partner gradually reduces the resistance after a full set is taken to failure. With each reduction in resistance, as many possible reps are completed and the resistance is then reduced again. This is continued until the resistance is approximately half the original resistance.

Negative reps

Negative reps are performed with much heavier weights. Assistants lift the weight, and then the weight trainer attempts to resist its downward progress through an eccentric contraction. Alternatively, an individual can use an exercise machine for negatives by lifting the weight with both arms or legs, and then lowering it with only one. Or they can simply lower weights more slowly than they lift them: for example, by taking two seconds to lift each weight and four seconds to lower it.

Partial reps

Partial reps, as the name implies, involves movement through only part of the normal path of an exercise. Partial reps can be performed with heavier weights. Usually, only the easiest part of the repetition is attempted.

Burns

Burns involve mixing partial reps into a set of full range reps in order to increase intensity. The partials can be performed at any part of the exercise movement, depending on what works best for the particular exercise. Also, the partials can either be added after the end of a set or in some alternating fashion with the full range reps.[52] For example, after performing a set of biceps curls to failure, an individual would cheat the bar back to the most contracted position, and then perform several partial reps.

Progressive movement training

Progressive movement training attempts to gradually increase the range of motion throughout a training cycle. The lifter will start with a much heavier weight than they could handle in the full range of motion, only moving through the last 3 to 5 inches of the movement. Throughout the training cycle, the lifter will gradually increase the range of motion until the joint moves through the full range of the exercise. This is a style that was made popular by Paul Anderson.

Time under tension

Time under tension or TUT repetitions are performed with lighter weights. Time under tension refers to the amount of time your muscle under stress during a set. This consists of the time spent in the concentric or the shortening phase, peak contraction phase, as well as the eccentric or the lengthening phase. For example, if you go perform a set of 10 reps and each rep takes 3 seconds to complete, your muscle is under tension for a total of 30 seconds. If you were to perform the same exercise but if you spent 2 seconds in the concentric phase, 1 second to stop during peak contraction, and 3 seconds to lower the weight during the eccentric phase of the rep, the same 10 reps would end up putting your muscles under tension for about 60 seconds.

Using a wrist strap

Wrist straps

Wrist straps (lifting straps) are sometimes used to assist in gripping very heavy weights. Wrist straps can be used to isolate muscle groups like in "lat pull-downs", where the trainee would primarily use the latissimus dorsi muscles of the back rather than the biceps. They are particularly useful for the deadlift. Some lifters avoid using wrist straps 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.

Loaded plyometrics involve the addition of weights to jumping exercises. The weights may be held or worn. For instance, vertical jumps whilst holding a trap bar or jumping split squats whilst holding dumbbells. This helps to enhance the explosive power of the athlete.[53]

Complex training, also known as contrast training, involves the alternation of weight training and plyometric exercises. Ideally, both sets of exercises should move through similar ranges of movement; such a pairing is called a complex, or contrast, pair. For instance, a set of heavy back squats at about 85–95% 1RM followed by a set of jumping exercises. The intention is to utilise the intense nervous system activation and increased muscle fibre recruitment from the heavy lift in the plyometric exercise; thereby increasing the power with which it can be performed. Over a period of training, this may result in the athlete being able to perform the plyometric exercise more powerfully, without the requirement of the preceding heavy lift.[54] Working on the same principles, a sports specific action may be incorporated instead of the plyometric exercise; the intention, in this case, being to increase the athlete's ability to perform the sports specific action more powerfully.

Ballistic training, sometimes referred to as power training, is based upon the principle of maximizing the acceleration phase of the exercise and minimizing the deceleration phase; this helps to improve the athlete's explosive power. On this basis, ballistic training may include exercises which involve the throwing of a weight, such as a medicine ball, or jumping whilst holding or wearing a weight.[55]

Contrast loading is the alternation of heavy and light loads i.e. a heavy bench press set at about 85–95% 1RM followed by a light bench press set at about 30–60% 1RM. The heavy set should be performed fast with the light set being performed as fast as possible. The joints should not be locked as this inhibits muscle fibre recruitment and reduces the speed at which the exercise can be performed. A loaded plyometric exercise, or ballistic exercise, may take the place of the light lift.

Similarly to complex training, contrast loading relies on the intense nervous system activation and enhanced muscle fibre recruitment from the heavy lift to help improve the power with which the subsequent exercise can be performed.[56] This physiological effect is commonly referred to as post-activation potentiation, or the PAP effect. By way of explanation, if a light weight is lifted, and then a heavy weight is lifted, and then the same light weight is lifted again, then the light weight will feel lighter the second time it is lifted. This is due to the increased PAP effect from the heavy lift allowing for greater power to be applied and thus making the subsequent lighter lift feel even lighter than before. Explosive power training programs are frequently designed to specifically utilize the PAP effect.

Bodybuilding is a sport in which the goal is to increase muscle size and definition. Bodybuilding increases the endurance of muscles, as well as strength, though not as much as if they were the primary goals. Bodybuilders compete in bodybuilding competitions, and use specific principles and methods of strength training to maximize muscular size and develop extremely low levels of body fat. In contrast, most strength trainers train to improve their strength and endurance while not giving special attention to reducing body fat below normal. Strength 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. Pre-contest training for bodybuilders is different again, in that they attempt to retain as much muscular tissue as possible while undergoing severe dieting. However, the bodybuilding community has been the source of many strength training principles, techniques, vocabulary, and customs.

Due to the androgenic hormonal differences between males and females, women are generally unable to develop large muscles regardless of the training program used.[68] Normally the most that can be achieved is a look similar to that of a fitness model. Muscle is denser than fat, so someone who builds muscle while keeping the same body weight will occupy less volume; if two people weigh the same (and are the same height) but have different lean body mass percentages, the one with more muscle will appear thinner.[69]

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 professional bodybuilder.

Some weight trainers perform light, high-repetition exercises in an attempt to "tone" their muscles without increasing their size.

The word tone derives from the Latin "tonus" (meaning "tension"). In anatomy and physiology, as well as medicine, the term "muscle tone" refers to the continuous and passive partial contraction of the muscles, or the muscles' resistance to passive stretching during resting state as determined by a deep tendon reflex. Muscle tonus is dependent on neurological input into the muscle. In medicine, observations of changes in muscle tonus can be used to determine normal or abnormal states which can be indicative of pathology. The common strength training term "tone" is derived from this use.

What muscle builders refer to as a toned physique or "muscle firmness" is one that combines reasonable muscular size with moderate levels of body fat, qualities that may result from a combination of diet and exercise.[70]

Muscle tone or firmness is derived from the increase in actin and myosin cross filaments in the sarcomere. When this occurs the same amount of neurological input creates a greater firmness or tone in the resting continuous and passive partial contraction in the muscle.

Exercises of 6–12 reps cause hypertrophy of the sarcoplasm in slow-twitch and high-twitch muscle fibers, contributing to overall increased muscle bulk. This is not to be confused with myofibril hypertrophy which leads to strength gains. Both, however, can occur to an extent during this rep range. Even though most are of the opinion that higher repetitions are best for producing the desired effect of muscle firmness or tone, it is not. Low volume strength training of 5 repetitions or fewer will increase strength by increasing actin and myosin cross filaments thereby increasing muscle firmness or tone. The low volume of this training will inhibit the hypertrophy effect.[71]

Lowered-calorie diets have no positive effect on muscle hypertrophy for muscle of any fiber type. They may, however, decrease the thickness of subcutaneous fat (fat between muscle and skin), through an overall reduction in body fat, thus making muscle striations more visible.

Exercises like sit-ups, or abdominal crunches, performs less work than whole-body aerobic exercises[72] thereby expending fewer calories during exercise than jogging, for example.

Hypertrophy serves to maintain muscle mass, for an elevated basal metabolic rate, which has the potential to burn more calories in a given period compared to aerobics. This helps to maintain a higher metabolic rate which would otherwise diminish after metabolic adaption to dieting, or upon completion of an aerobic routine.[73]

In general, one can lose weight by being in a calorie deficit. A calorie deficit can be done in different ways; It can be done by consuming less than the amount of calories that are required to maintain your current body weight or by increasing the energy expenditure, enough that is more than the calorie intake. Lean muscles require calories to maintain themselves at rest, which will help reduce fat through an increase in the basal metabolic rate.

Orthopaedic specialists used to recommend that children avoid weight training because the growth plates on their bones might be at risk. The very rare reports of growth plate fractures in children who trained with weights occurred as a result of inadequate supervision, improper form or excess weight, and there have been no reports of injuries to growth plates in youth training programs that followed established guidelines.[76][77] The position of the National Strength and Conditioning Association is that strength training is safe for children if properly designed and supervised.[78]

Younger children are at greater risk of injury than adults if 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. As a result, supervision of minors is considered vital to ensuring the safety of any youth engaging in strength training.[76][77]

Strength training is the fourth most popular form of fitness in Australia.[79] Due to its popularity amongst all ages, there is great scepticism on what the appropriate age to commence strength training in young athletes is. Some points of the opposing view of strength training in young adolescence are stunted growth, health and bone problems in later stages of life and unhealthy eating habits.[80] Studies by Australian experts that have been recognised by the Australian Institute of Sport (AIS) have debunked these myths. There is no link between any prolonged health risks and strength training in pre-adolescence if the procedures of strength training are followed correctly and under suitable supervision. Strength training for pre-adolescents should focus on skills and techniques. Children should only work on strengthening all the big muscle groups, using free weight and body weight movements with relatively light loads. The benefits of these practices include increased strength performance, injury prevention and learning good training principles.[81]

Older adults are prone to loss of muscle strength.[82][83] With more strength older adults have better health, better quality of life, better physical function[83] and fewer falls.[83] In cases in which an older person begins strength training, their doctor or health care provider may neglect to emphasize a strength training program which results in muscle gains. Under-dosed strength training programs should be avoided in favor of a program which matches the abilities and goals of the person exercising.[84]

In setting up an exercise program for an older adult, they should go through a baseline fitness assessment to determine their current limits. Any exercise program for older adults should match the intensity, frequency, and duration of exercise that the person can perform. The program should have a goal of increased strength as compared to the baseline measurement.[84]

Recommended training for older adults is three times a week of light strength training exercises. Exercise machines are a commonly used equipment in a gym setting, including treadmills with exercises such as walking or light jogging. Home-based exercises should usually consist of body weight or elastic band exercises that maintain a low level of impact on the muscles. Weights can also be used by older adults if they maintain a lighter weight load with an average amount of repetitions (10–12 reps) with suitable supervision. It is important for older adults to maintain a light level of strength training with low levels of impact to avoid injuries.[85]

Older people who exercise against a resistance or force become stronger.[83] Progressive resistance training (PRT) also improves physical functioning in older people, including the performance of simple (e.g.: walking, climbing stairs, rising from a chair more quickly) and complex daily activities (e.g.: bathing, cooking).[83] Caution is recommended when transferring PRT exercises for clinical populations, as adverse effects are unclear.[83]