Training may require different types of strength, each of which is important for a particular sport and athlete. Strength types can be distinguished by the quality of strength, the strength-time curve, the type of muscle activity, the athlete’s body weight, and the degree of specificity.

Strength: its qualities 

The desired effect of a strength training method always falls into one of three categories or qualities: maximum physical strength , power, and muscle endurance.

Maximum strength 

Maximum strength is the ultimate strength that the neuromuscular system can generate during contraction. This quality is enhanced through a combination of structural adaptation (hypertrophy) and, for the most part, neural adaptation (mainly in the form of improved intermuscular and intramuscular coordination).

Maximum strength is determined by the heaviest load the athlete is capable of lifting in one attempt and is expressed as the 100% maximum. For training purposes, athletes should know their maximum strength level for the most important (fundamental) exercises, as this provides a basis for calculating the load for almost every phase of strength training.


Power is the product of two abilities – strength and speed – and is itself the ability to use maximum force in the shortest amount of time. Unlike powerlifting, where athletes express (maximum) strength without a time limit, athletes in other sports face time constraints within which they must develop their maximum strength.

Examples are kicks by running athletes in individual and team sports, punching and kicking in combat sports, and swing and throwing in baseball. Power is trained in methods that enhance the rapid expression of strength, thus improving the thermal energy expenditure of active motor units. Power can only be increased by using specific techniques after the maximum strength training phase.

Muscle endurance 

Muscle endurance is the ability of a muscle to keep working for an extended period. Most sports require endurance , and muscle endurance training methods develop both the neural and metabolic aspects of a sport. We distinguish four types of proper sports methods of muscle endurance training: strength endurance (10-30 seconds or up to 15 seconds with incomplete rest; lactate power), short muscle endurance (30 seconds – 2 minutes; lactate performance), average muscle endurance (2- 8 minutes; aerobic power) and long muscular endurance (over 8 minutes; aerobic performance ).

Strength: Power vs. Time Curve

If we analyze the force-time curve (see figure), we can distinguish the following types of strength: starting strength, explosive strength (strength development range), power (starting strength plus explosive strength) and maximum strength.

Starting power

Starting force is expressed at the onset of concentric action and is usually measured after 50 milliseconds. Its level depends on the ability to voluntarily engage as many motor units as possible (i.e., intramuscular coordination) at the beginning of the movement.

Explosive strength or the rate of development of strength

Explosive strength is the rate of increase in strength at the start of a concentric exercise. Its level depends on the ability to use more motor units or to increase the energy expenditure of active units in order to increase the performance of strength.


The starting force and the explosive force together represent what we call power, or, according to others, “velocity force.” A high level of power is usually required to achieve high performance in sports, as some sports have restrictions on the use of force.

Maximum strength

Maximum strength is the maximum level of strength that an athlete can achieve in a movement.

Strength: Muscular Activity 

Three types of strength can be distinguished according to muscular activity: concentric, isometric and eccentric.

Concentric force 

With concentric action, the muscle tense and contract, thus moving the joint. Maximum force is usually measured with the highest load that can be lifted concentrically. Eccentric action usually either precedes or follows this.

Isometric strength

With isometric action, the muscle tenses, while not contracting or stretching; this result is obtained when the generated force is equal to the external resistance or when the external resistance is stationary. A high proportion of isometric primary muscle activity is required for many motor sports as well as cycling motocross, sailing and combat sports. The need for this should be considered when designing a strength training program. Isometric force can exceed concentric force by 20 percent.

Eccentric force

With eccentric action, the muscle creates less tension than external resistance, thus stretching the muscle. A high level of eccentric strength is recommended for sports that require jumping, sprinting, and changing directions. The eccentric force can exceed the concentric force by 40 percent.

Strength: relation to body weight

Maximum strength training methods induce both neural and muscle adaptations. As described below, the load parameters can be manipulated to increase either the athlete’s body weight and strength, or strength alone, while maintaining body weight. For this reason, we distinguish two types of strength: absolute and relative.

Absolute strength

Absolute strength is the ability of an athlete to generate maximum strength regardless of body weight. A high level of absolute strength is required in order to excel in some sports (for example, shot put and the heaviest categories in weightlifting and wrestling). The increase in strength parallels the gain in body weight in those athletes who train to increase absolute strength.

Relative strength 

Relative strengthis the ratio between maximum strength and body weight. A high level of relative strength is important in gymnastics, sports where athletes are categorized by weight (e.g. wrestling, boxing, judo, Brazilian Jiu-Jitsu, and mixed martial arts), team sports that require frequent directional changes, and sprint and jumping in athletics. For example, a gymnast may not succeed in performing a vertical stop on the rings until the ratio of the relative strength of the muscles involved is at least one to one; in other words, the absolute strength should at least be enough to compensate for the athlete’s body weight. Of course, increasing body weight changes the ratio – as body weight increases, relative strength decreases, unless it increases accordingly.

Strength: the degree of specificity

We distinguish two types of strength according to the degree of specific sports biomechanical and physiological similarity of training means and methods involved in the program: general strength and specific strength.

Shared strength

Overall strength is the foundation of the entire training program. In the early years of sports training, it is important to focus on it. Low levels of overall strength can limit the athlete’s overall progress. As a result, the body can be prone to injury and possibly even develop asymmetrically or have a reduced ability to accumulate muscle strength, as well as a lower ability to develop necessary athletic skills.

Anatomical adaptation, hypertrophy and macrocycles of maximum strength are involved in the development of the athlete’s overall strength. Anatomical adaptation focuses on developing overall core strength as well as muscle balance and injury prevention through tendon strengthening. As the name suggests, anatomical adaptation prepares the body for the more challenging stages that follow. Overall strength is further increased by structural changes caused by macrocycles of hypertrophy and neural adaptations resulting from macrocycles of maximum strength.

Specific power

Specific strength training takes into account the specificity of a particular sport, such as ergogenesis (contribution of energy systems), plane of motion, primary muscles, joint range of motion and muscle activity. As the name suggests, this type of strength is specific to each sport and requires significant analysis. Therefore, it makes no sense to compare the strength levels of athletes involved in different sports. Specific strength training should be incorporated gradually towards the end of the preparatory period for all advanced athletes.

Power reserve

Strength is the difference between maximum strength and the strength required to apply a skill in a competitive environment. For example, one study of strength techniques measured the average strength of rowers during a stroke during a race, which was found to be 56 kilograms. The same athletes demonstrated absolute strength when lifting 90 kilograms of weight on the chest. If we subtract the average strength during the race (56 kilograms) from the absolute strength (90 kilograms), we get a reserve of strength of 34 kilograms. In other words, the ratio of average strength to absolute strength is approximately 1: 1.6.

Other test athletes in the same study showed higher strength reserves and a 1: 1.85 ratio. Of course, the rowers of this group performed better in boat races, thus confirming that the athlete with more strength is capable of demonstrating higher athletic performance. Therefore, the strength training coach should strive to help athletes achieve the highest level of maximum strength during the week of strength training in a rational proportion to more specific sessions to prevent negative transference.