Muscle Function During Acute ExerciseChapters 8 & 19 (pp. 393-397)Acute Force Productionjust right too muchWithout making any permeant changes to the neuromuscular system, what could cause the muscle to generator more of less force?IIbIIbIIaIIbIIIaIIbIIIaA single muscle with IIb, IIa, and I muscle fibersMotor UnitsNote the order of recruitmentIIIIIaIIaIIbMotor UnitsIIbIIaI I IIa IIbMotor UnitsIIbIIaI I IIa IIb Number (and order) of MUMotor UnitsIIbIIaI I IIa IIb FrequencyNumber (and order) of MUMotor UnitsSummationTetanusSingle TwitchesMotor UnitsMotor UnitsNote the frequency of stimulationMotor Units1. The number (and type) of Motor Units2. The Frequency of stimulationFiber ArrangementStrongersMuscle LengthSpeed of ContractionFastContractionLow ForceSpeed of ContractionSlowContractionFastContractionLow ForceSpeed of ContractionSlowContractionFastContractionLow ForceHigh ForceSpeed of ContractionSlowContractionFastContractionLow ForceHigh ForceForce Regulation SummaryMotor UnitsNumberFrequencyFiber ArrangementMuscle LengthSpeed of ContractionMythsMyths1.A bigger muscle is not always the stronger muscle.Myths1.A bigger muscle is not always the stronger muscle. 2.Stronger is not always better.Strength = force producedPower = force produced x distance / timeMuscle FatigueHow is fatigue defined?Types of Fatigue1.Central fatigue2.Peripheral fatigueFig 19.2Central FatiguePeripheral FatigueATPPeripheral FatigueATPPeripheral FatigueATPPeripheral FatigueATPPeripheral FatigueATPPeripheral FatigueATPPeripheral FatigueATPMuscle SorenessAcute SorenessAcid build upEdemaDelayed Onset Muscle Soreness(DOMS)Delayed Onset Muscle Soreness(DOMS)Delayed Onset Muscle Soreness(DOMS)NOT due to lactic acid!Delayed Onset Muscle Soreness(DOMS)NOT due to lactic acid!Delayed Onset Muscle Soreness(DOMS)NOT due to lactic acid!Delayed Onset Muscle Soreness(DOMS)NOT due to lactic acid!Delayed Onset Muscle Soreness(DOMS)NOT due to lactic acid!Myth BusterLactic acid does not cause delayed onset muscle sorenessLactate, the major by-product of lactic acid, is removed or cleared within hours after