Strength and the MuscularSystemSupertraining, Chapter 1
A Model of the Muscle ComplexIt is relatively meaningless todiscuss muscle action withoutconsidering the role played bythe connective tissuesassociated with muscle.Connective tissues occur inthe sheaths of muscle and itssub-units at all levels.
The Muscle ModelSeries Elastic Component (SEC)Tendon, Myofilaments, Z-Discs, TitinBasically, the tendons and actual muscle fibersParallel Elastic Component (PEC)Muscle Sheaths and sarcolemma
Muscle Model ForcesPEC is responsible for force exerted by arelaxed muscle when it is stretchedbeyond its resting lengthSEC is put under tension by the forcedeveloped in an actively contractedmuscle
Who Cares?You should care for 2 reasons….well 3.1. So you can sound smart when talking toexercise physiologists.2. So you know that more than just the muscleis involved in human movement, elastic partsare very important too!3. So you know that static stretching influencesthe PEC more than the SEC and that staticROM is different than dynamic ROM.
Muscle Actions:Basic TerminologyAgonist: Prime movers in an actionAntagonist: Muscles acting in opposition toagonistStabilizers: Muscles that stabilize a bodysegment while other muscles carry out amovement
Muscle Action Examples:Agonist: In a leg extension exercise, thequadriceps are going to be agonists of theexercise.
Muscle Action Examples:Antagonist: In a leg extension on amachine, the hamstrings would be theantagonists to the movement. If thehamstrings were firing during the upwardportion of the movement, the action wouldbe severely affected, or could not happen.
Types of Muscle ContractionIsometricConcentricEccentric
Types of Muscle ContractionIsometric ContractionThere is ALWAYS an isometric phase of anylift, jump, throw, etc.The isometric phase of a slow movement, suchas a barbell squat will take much longer thanthe isometric phase of a vertical jump.The brief isometric contraction betweeneccentric and concentric phases in plyometricsis of great importance!
Types of Muscle ContractionConcentric contractionThis is the part of contraction where positivework is done. The power of this contraction isoften influenced by the previous two phases ofmuscle contraction (eccentric/concentric)Eccentric (yielding) contractionCan produce 30-40% greater muscle tensionthan other two contractionsDOMS (delayed onset muscle soreness)producer
Eccentric ContractionsThe eccentric phase can store moreenergy than the other two phases.Because of the elastic properties of themuscle-tendon complex, the more energystored during the eccentric phase, themore energy is released in the concentricphase.We will get to this more later when we talkabout the Stretch-Shortening Cycle indetail.
The Fundamental Principle of StrengthTrainingThe production and increase of strengthboth depend on neuromuscular processes.Strength is not primarily a function ofmuscle size, but one of the appropriatemuscles powerfully contracted by effectivenervous stimulation.Example: Tara Nott, Olympic Weightlifter
The Fundamental Principle of StrengthTrainingBasically the nervous system ultimatelycontrols the outcome of a trainingprogram.
Nervous SystemThe central nervous system (CNS) is thepart of the nervous system that functionsto coordinate the activity of all parts of thebodies of multicellular organisms(Wikipedia)CNS is a term you should be familiar with!
The Neuromuscular System and Strength Stimulation (training) of the nervous systemproduces two basic effects on the body:Functional muscle actionMuscle hypertrophy(hypertrophy=increase in size of the muscle) With this in mind there are two basic types ofstrength training:Functional strength trainingStructural strength training
Functional vs. StructuralStructural strength training would aimspecifically at producing musclehypertrophy (increase in muscle size).Functional strength training is associatedwith improving static strength, speed-strength, muscle endurance, and reactiveability.
A functional/structural scaleHere is a scale of exercises for a track andfield sprinter for the quadriceps muscle
A note about functional training Functional training is fairly simple, it involvesmotor movements that are close to that of theprimary sport. It can also be simply playing thegiven sport. Typically these movements will below or high amplitude jumping exercises,general calisthenics, sprints of varyingdistances, and other elastic exercises. In the early stages of training or duringstagnation at an advanced level, the functionalstages of training should precede „structural‟training work.
Don‟t get carried away when you hear“functional” Some trainers takefunctional training out ofcontext Trying to add too much„complexity‟ to anexercise or making itoverly sport specific canalter firing patterns. Also,too much element ofbalance in an exercisewill take away from forceproduction ability.Not “Functional” Training
A breakdown of „functional‟ training:4 Processes involvedIntermuscular coordinationIntramuscular coordinationFacilitory and inhibitory reflexive processesMotor learning
Intermuscular CoordinationCoordination between different musclegroups.This involves the synchronizing orsequencing of muscles in certainmovements.Some muscles might be inhibited fromcooperating, while some might bedisinhibited from cooperating in amovement.
Intramuscular Coordination This is the improvementof coordination of musclefibers in the samemuscle. Increase in number ofmuscle fibers activated ordeactivated Rate Coding: control oftension by modifying thefrequency that the fibersfire at Pattern Encoding: controlof tension by synchronizingthe firing of different typesof muscle (e.g. slow or fasttwitch fibers….sprintexample)
Motor Learning Motor learning is the process of programmingthe CNS to carry out specific movementtasks. Most gains found early in a resistanceprogram are due to motor learning! Motor learning will continue as the intensityand complexity of the exercise increases,because skill in demanding conditions ismuch different than skill in basic conditions.
CNS is important in training, so what?The way you train can affect the change ofthe CNS.Strength training on machines can modifythe circuitry and programming of the brainand thereby reduce the functionalcapability of the muscles used for aspecific movement.HIT trainees would disagree
CNS is important in training, so what?Because of the rapid changes produced inthe brain by repeated stimuli, even shortperiods of inappropriate patterns ofstrength training can be detrimental tosporting performanceExample: If I am a sprinter and train with a50lb vest for 3 weeks, and then competein a big meet, my motor patterns will bealtered, and I won‟t do very well.
CNS is important in training, so what?Over reliance on ergogenic devices likebelts, gloves, knee wraps and heelwedges can modify the neuromuscularsystem so that safe and effective trainingwithout them can become difficult
CNS is important in training, so what? The existence ofindividual style revealsthat each person willprogram the CNS insubtly different ways.This means that anattempt to place astereotypes, generalpattern of movementmight prevent an athletefrom reaching their fullpotentialAn Example of 2 Jumping Styles
Structural and FunctionalDeterminants of StrengthStructural FactorsCross-sectional area of muscleDensity of muscle fibers per unit cross-sectionalarea. (Muscle density)Efficiency of mechanical leverage across thejointMuscle insertionPennation angle of muscle
Functional Determinants of StrengthThe number of muscle fibers contractingsimultaneouslyThe rate of contraction of muscle fibersThe efficiency of synchronisation of thefiring of muscle fibersThe conduction velocity in the nerve fibers
Functional DeterminantsThe degree of inhibition of muscle fiberswhich do not contribute to the movementThe proportion of large diameter musclefibers activeThe efficiency of cooperation betweendifferent types of muscle fiber (fast andslow)
Functional DeterminantsThe efficiency of the stretch-shorteningcycleThe excitation threshold of the nerve fiberssupplying the musclesThe initial length of the muscles beforecontraction