Concept of Strength Training

Strength training is a type of physical exercise specializing in the use of resistance to induce muscular contraction which builds the strength, anaerobic endurance, and size of skeletal muscles. 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, increased metabolism, improved cardiac function, and elevated HDL ("good") cholesterol. Training commonly uses the technique of progressively increasing the force output of the muscle through incremental weight increases and uses a variety of exercises and types of 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 (Wikipedia, 2014).

Until the 20th century, the history of strength training was very similar to the 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 (Wikipedia, 2014).

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.

Basic Principles of Strength Training

The basic principles of strength training involve a manipulation of the number of repetitions (reps), sets, tempo, exercises and force to cause desired changes in strength, endurance or size by overloading of a group of muscles. A wide spectrum regimens are adopted to achieve different results, but the classic formula recommended by the American College of Sports Medicine reads as follows:

• 8 to 12 repetitions of a resistance training exercise for each major muscle group at an intensity of 40% to 80% of a one-repetition max (RM) depending on the training level of the participant.
• Two to three minutes of rest is recommended between exercise sets to allow for proper recovery.
• Two to four sets are recommended for each muscle group

This is the prescription for the average individual. A nuanced reading of this prescription holds that muscles should be trained in concert with surrounding muscles,(e.g. chest/shoulders/triceps) and for maximum training effect lifts should be performed with heavy (70-85%1RM, aka high intensity) weights and multiple sets with fairly long (2-5 min. depending on intensity) rest periods between sets. Typically 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. There are cases when cheating is beneficial, as is the case where weaker groups become the weak link in the chain and the target muscles are never fully exercised as a result (Wikipedia, 2014).

The benefits of strength training include increased muscle, tendon and ligament strength, bone density, flexibility, tone, metabolic rate and postural support.

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

• Exercise - different exercises involve moving 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 lbs, then their RM for that weight would be 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.

Realization of training goals

According to popular theory:

• Sets of one to five repetitions primarily develop strength, with more impact on muscle size and none on endurance.
• Sets of six to twelve repetitions develop a balance of strength, muscle size and anaerobic endurance.
• Sets of thirteen to twenty repetitions develop anaerobic endurance, with some increases to muscle size and limited impact on strength.
• Sets of more than twenty repetitions do still use the anaerobic system, but usually at a rate through which it can consistently remove the lactic acid generated from it.

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 (Wikipedia, 2014).

Variable	Training goal
	Strength	Power	Hypertrophy	Endurance	Speed
Load (% of 1RM)	80-90	45-60	60-80	40-60	30
Reps per set	1-5	1-5	6-12	13-60	1-5
Sets per exercise	4-7	3-5	4-8	2-4	3-5
Rest between sets (mins)	2-6	2-6	2-5	1-2	2-5
Duration (seconds per set)	5-10	4-8	20-60	80-150	20-40
Speed per rep (% of max)	60-100	90-100	60-90	60-80	100
Training sessions per week	3-6	3-6	5-7	8-14	3-6

Source: Siff (2003)

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

Progressive overload

In one common method, 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. 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. 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, perform only 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 (Wikipedia, 2014).

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

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.

Intensity, volume, and frequency

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:

Type	High	Med	Low
Intensity (% of 1RM)	80-100%	50-70%	10-40%
Volume (per muscle)	1 exercise	2 exercises	3+ exercises
Sets	1 set	2-3 sets	4+ sets
Reps	1-6 reps	8-15 reps	20+ 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 (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.

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.

Periodization

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 he will finish with.

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 number of repetitions decreases while the weight increase (Wikipedia, 2014)