Muscular Strength and Endurance There are many types of strength that an in- dividual may need in order to improve perfor- mance and/or function. In order to understand the benefits of exercise, we must first define and describe the different types of strength.

Neural Factors Influencing Strength Gains Exercise elicits a training stimulus. One effect is structural (e.g. hypertrophy of muscles and connective tissues) while the other is functional. Functional affects of training will be seen as both increased intramuscular coordination (within a muscle) and increased intermuscular (within a group of muscles). During any movement, cer- tain muscles will be activated as a primary, sec- ondary, stabilizer, and/or neutralizer, to coincide with facilitation (actual recruitment or disinhibi- tion) or inhibition (shut off). This sequence of events takes place during all movements, espe- cially during the initial stages of training (motor learning/motor ability stage).

adaptations to strength training Increased strength due to increased motor unit recruitment (i.e. able to contract a greater num- ber of motor units simultaneously)

Increased strength due to muscle hypertrophy (increase in muscle cell size)

Possible conversion of Type 1 to Type II fibers

Possible hyperplasia leading to hyper- trophy (increase in muscle cell number - rare)

Increased ATP, CP and glycogen stores (energy stores)

Increase in size of the left and right ventricles of the heart (wall thickness and chamber diameter)

net muscle actions

concentric

Definition: Shortening of a muscle fiber against a load

“Raises” the load “Accelerates” the load Ex: Upward phase of a

dumbbell biceps curl

eccentric

Definition: Lengthening of a muscle fiber against a load§

-“Lowers” the load

§-Ex: Downward phase of a dumbbell bicep curl

isometric

Definition: Where a muscle neither lengthens nor short- ens against a load (no net joint movement). A co- contraction of agonist and antagonist muscles.

§-Ex: Holding the elbow still at 90˚ in a dumbbell bicep curl

isotonic

Definition: Exercise where a concentric and/or eccentric action is generated to move a load through a range of mo- tion where the force on the muscle does not change

isokinetic

Definition: Exercise on a spe- cialized piece of equipment where the muscle action speed is constant

 

types of strength

absolute strength

The maximum amount of force an individual can produce in a one repeti- tion maximum lift (one rep max or 1RM), irrespective of body weight and time of force development. This type of strength is particularly important for shot putters and football linemen where bodyweight has a high correla- tion to an increase in sports performance.

relative strength

The maximum force that muscles can generate in relation to one’s body weight. This type of strength is important for individuals who have to move their entire body weight, such as a gymnast. This type of strength is also important for individuals who want to get stronger, but don’t necessarily want to gain mass, as well as an important strength stage to fulfill prior to mass-building.

strength endurance (muscular endurance)

The ability to sustain muscular contractions for a long duration of time. This type of strength is important for mid-level endurance events such as cycling or rowing.

power

The physics definition of power is Force x Distance � Time. In other words, power measures how quickly work is performed (Work = Force x Distance). The different ways to increase power are to increase the Force (ex: weight), increase the Resisted Distance (ex: up if force is due to gravity) or to de- crease the Time (ex: move faster). The factor most influential in increasing power is decreasing the time to perform a movement or exercise.

What are the various types of strength? Be able to identify exercises which emphasize a particular type of strength. What factors contribute to muscle soreness?

     This  has  been  a  small  sample  of  what  you  will  learn  when  you  enroll  on  the  NESTA  Personal  Fitness  Trainer  Certification.        

Hypertrophy Intermuscular

Intramuscular