strength and the muscular system

Strength and the Muscular System

Supertraining, Chapter 1

A Model of the Muscle Complex

It is relatively meaningless to discuss muscle action without considering the role played by the connective tissues associated with muscle.

Connective tissues occur in the sheaths of muscle and its sub-units at all levels.

The Muscle Model

Series Elastic Component (SEC)Tendon, Myofilaments, Z-Discs, Titin Basically, the tendons and actual muscle fibers

Parallel Elastic Component (PEC)Muscle Sheaths and sarcolemma

A Better Picture

Muscle Model Forces

PEC is responsible for force exerted by a relaxed muscle when it is stretched beyond its resting length

SEC is put under tension by the force developed in an actively contracted muscle

Who Cares?

You should care for 2 reasons….well 3. 1. So you can sound smart when talking to

exercise physiologists.2. So you know that more than just the muscle

is involved in human movement, elastic parts are very important too!

3. So you know that static stretching influences the PEC more than the SEC and that static ROM is different than dynamic ROM.

Muscle Actions:

Basic TerminologyAgonist: Prime movers in an actionAntagonist: Muscles acting in opposition to

agonistStabilizers: Muscles that stabilize a body

segment while other muscles carry out a movement

Muscle Action Examples:

Agonist: In a leg extension exercise, the quadriceps are going to be agonists of the exercise.

Muscle Action Examples:

Antagonist: In a leg extension on a machine, the hamstrings would be the antagonists to the movement. If the hamstrings were firing during the upward portion of the movement, the action would be severely affected, or could not happen.

Types of Muscle Contraction

IsometricConcentricEccentric

Types of Muscle Contraction

Isometric ContractionThere is ALWAYS an isometric phase of any lift,

jump, throw, etc. The isometric phase of a slow movement, such

as a barbell squat will take much longer than the isometric phase of a vertical jump.

The brief isometric contraction between eccentric and concentric phases in plyometrics is of great importance!

Types of Muscle Contraction

Concentric contractionThis is the part of contraction where positive

work is done. The power of this contraction is often influenced by the previous two phases of muscle contraction (eccentric/concentric)

Eccentric (yielding) contractionCan produce 30-40% greater muscle tension

than other two contractionsDOMS (delayed onset muscle soreness)

producer

Eccentric Contractions

The eccentric phase can store more energy than the other two phases. Because of the elastic properties of the muscle-tendon complex, the more energy stored during the eccentric phase, the more energy is released in the concentric phase.

We will get to this more later when we talk about the Stretch-Shortening Cycle in detail.

A Dynamic example

An Example:

An Example:

The Fundamental Principle of Strength Training

The production and increase of strength both depend on neuromuscular processes.

Strength is not primarily a function of muscle size, but one of the appropriate muscles powerfully contracted by effective nervous stimulation.

Example: Tara Nott, Olympic Weightlifter

The Fundamental Principle of Strength Training

Basically the nervous system ultimately controls the outcome of a training program.

Nervous System

The central nervous system (CNS) is the part of the nervous system that functions to coordinate the activity of all parts of the bodies of multicellular organisms (Wikipedia)CNS is a term you should be familiar with!

The Neuromuscular System and Strength

Stimulation (training) of the nervous system produces two basic effects on the body:Functional muscle action Muscle hypertrophy

(hypertrophy=increase in size of the muscle)

With this in mind there are two basic types of strength training:Functional strength trainingStructural strength training

Functional vs. Structural

Structural strength training would aim specifically at producing muscle hypertrophy (increase in muscle size).

Functional strength training is associated with improving static strength, speed-strength, muscle endurance, and reactive ability.

A functional/structural scale

Here is a scale of exercises for a track and field sprinter for the quadriceps muscle

A note about functional training

Functional training is fairly simple, it involves motor movements that are close to that of the primary sport. It can also be simply playing the given sport. Typically these movements will be low or high amplitude jumping exercises, general calisthenics, sprints of varying distances, and other elastic exercises.

In the early stages of training or during stagnation at an advanced level, the functional stages of training should precede ‘structural’ training work.

Don’t get carried away when you hear “functional”Some trainers take functional training out of contextTrying to add too much ‘complexity’ to an exercise or

making it overly sport specific can alter firing patterns. Also, too much element of balance in an exercise will take away from force production ability.

Not “Functional” Training

A breakdown of ‘functional’ training:

4 Processes involvedIntermuscular coordinationIntramuscular coordinationFacilitory and inhibitory reflexive processesMotor learning

Intermuscular Coordination

Coordination between different muscle groups.

This involves the synchronizing or sequencing of muscles in certain movements.

Some muscles might be inhibited from cooperating, while some might be disinhibited from cooperating in a movement.

Intramuscular Coordination

This is the improvement of coordination of muscle fibers in the same muscle. Increase in number of muscle fibers activated or deactivated Rate Coding: control of tension by modifying the frequency that

the fibers fire at Pattern Encoding: control of tension by synchronizing the firing

of different types of muscle (e.g. slow or fast twitch fibers….sprint example)

Motor Learning

Motor learning is the process of programming the CNS to carry out specific movement tasks.

Most gains found early in a resistance program are due to motor learning!

Motor learning will continue as the intensity and complexity of the exercise increases, because skill in demanding conditions is much different than skill in basic conditions.

CNS is important in training, so what?

The way you train can affect the change of the CNS.

Strength training on machines can modify the circuitry and programming of the brain and thereby reduce the functional capability of the muscles used for a specific movement. HIT trainees would disagree

CNS is important in training, so what?

Because of the rapid changes produced in the brain by repeated stimuli, even short periods of inappropriate patterns of strength training can be detrimental to sporting performance

Example: If I am a sprinter and train with a 50lb vest for 3 weeks, and then compete in a big meet, my motor patterns will be altered, and I won’t do very well.

CNS is important in training, so what?

Over reliance on ergogenic devices like belts, gloves, knee wraps and heel wedges can modify the neuromuscular system so that safe and effective training without them can become difficult

CNS is important in training, so what?

The existence of individual style reveals that each person will program the CNS in subtly different ways. This means that an attempt to place a stereotypes, general pattern of movement might prevent an athlete from reaching their full potential

An Example of 2 Jumping Styles

Structural and Functional Determinants of StrengthStructural Factors

Cross-sectional area of muscleDensity of muscle fibers per unit cross-sectional

area. (Muscle density)Efficiency of mechanical leverage across the

jointMuscle insertionPennation angle of muscle

Functional Determinants of Strength

The number of muscle fibers contracting simultaneously

The rate of contraction of muscle fibersThe efficiency of synchronisation of the

firing of muscle fibersThe conduction velocity in the nerve fibers

Functional Determinants

The degree of inhibition of muscle fibers which do not contribute to the movement

The proportion of large diameter muscle fibers active

The efficiency of cooperation between different types of muscle fiber (fast and slow)

Functional Determinants

The efficiency of the stretch-shortening cycle

The excitation threshold of the nerve fibers supplying the muscles

The initial length of the muscles before contraction