Chapter 13, 21 The Physiology of Training: Physiological Effects of Strength Training pp. 267-270 270 Training for Anaerobic Power p. 430-431 431
Types of Contractions Dynamic, Isotonic, or concentric Muscle shortens with varying tension while lifting constant load Isometric, or static Tension develops but there is no change in the length of the muscle Eccentric Muscle lengthens while contracting or developing tension Isokinetic Tension developed while shortening is maximal over the full range of motion
Isotonic Contraction Muscle does not exert same tension throughout range of motion (ROM) Tension depends on Length tension relationship Angle of pull on skeleton Speed of shortening Composition of muscle (Type I and II)
Length Tension Relationship Optimal overlap of myofilaments Maximal tension Opposite ends Too much overlap Actin out of range of crossbridges
Joint Angle Strength curve Varying amounts of force generated Due to biomechanical differences in joint angle Peak force occurs at 100-120 120 o
Characteristics of Skeletal Muscle Mito high Fatigue Resistance Type 1 Type 2a Type 2x high hi/mod low hi/mod Predominant energy system aerobic Speed of shortening low Capillary density high low combination anaerobic intermediate high low low
Resistance Training
Resistance Training Neural and muscular factors contribute to strength gains Neural adaptations for initial gains Learning Coordination Ability to recruit prime movers Muscular adaptations for long term gains Increase in size of prime movers Hypertrophy
Kannus (1992) Neural Factors Trained limb vs untrained limb One arm is strength trained Some of the training effect is transferred to other arm Trained arm-strength gain related to muscle hypertrophy and activation of motor units Untrained arm-strength due solely to increased activation of motor units-neural neural factor
Neural Adaptations EMG activity Enhanced ability to recruit motor units leads to increased force production Rate of motor unit firing Larger MU have higher firing rates Motor unit firing rate can be enhanced by training explosively recruited during training in order to be used in performance
Muscular Adaptations Muscular Enlargement Type II can develop a bit more tension than I Strength training causes hypertrophy of both types, Type II changes more than I Alterations in fiber types Rigorous exercise training alters fiber types Alters type IIb to type IIa These changes are small and are not complete transformation Capability for adaptive change-myoplasticity
Physiologic Changes Hypertrophy Number and size of myofibrils Increased amount of contractile protein Increased capillary density Increased amount/strength of connective tissues
Biochemical Changes Increases in PC, ATP, Glycogen Little change in ATP turnover enzymes Increases/no change in glycolytic enzymes Significant increases in Krebs cycle enzymes Decrease in density of mito due to increase in size of myofibrils
Biochemical Changes Selective hypertrophy of Type II Shift from IIb to IIa with both strength and endurance training programs Changes small and inconsistent
Hypertrophy
Training Programs
Chapter 21 Training for Improved Anaerobic Performance
Training Principles To improve one s s ability to perform a certain task involves working SPECIFIC muscles or organ systems at an INCREASED resistance Specificity of Training Identify the predominant energy system ATP-PC PC Lactic acid Aerobic
Classification of Activities
Training Principles Intensity Considered most important Energy source Estimated from performance time
Training Principles Guidelines for frequency and duration Intensity HR 5 to 15% above HR at LT Frequency 3 to 4 days/week Sessions/day 1 or 2 Duration ATP-PC PC-repeated work bouts 25 sec or less Glycolysis-repeated work bouts of 3 to 4 min or less
Training Principles Aerobic system Important for clearing lactate Regeneration of ATP-PC PC Useful in sports with anaerobic component interspersed with aerobic component Ice hockey Tables 11.6 and 11.7 Work rates for interval training prescriptions
Training Principles Intervals important- rest Partial replenishment of ATP-PC PC during rest O 2 -myoglobin restored Replenishment primarily through aerobic system
ATP-PC PC Recovery
Training Principles Training to improve ATP-PC PC Interval training High intensity intervals (5 to 10 sec) Rest intervals (30 to 60 s) Fitness of individual
Physiologic Basis Improved capacity of ATP-PC PC Through increased muscular stores of ATP Increase muscular stores of ATP (25%) Increased muscular stores of PC (40%) Increased enzyme activity ATPase ATP + H 2 O ADP + Pi Myokinase ADP + ADP ATP + AMP Creatine kinase ADP + CP ATP + C Creatine kinase (mito( mito) ATP + C ADP + CP
Training Principles Anaerobic glycolysis system Increasing dependence for energy production from An Gly begins after about 10 s of maximal effort High intensity intervals of 20 to 60 s Drastic reduction in muscle glycogen stores Alternate hard and light interval training days
Training Principles Intensity > 90% VO 2 max PC stores Rapid drop, slower drop ATP Drops a little Muscle lactate Sharp rise Blood lactate Rise is less than in muscle
Physiologic Basis Glycolytic enzymes (10 to 25% increase) Phosphorylase Phosphofructokinase Lactate dehydrogenase
Training Principles Anaerobic training improves muscles capacity to tolerate La that accumulates with anaerobic glycolysis H + ion thought to interfere Metabolism (PFK) Contractile process Muscle buffering capacity improves with training 12 to 50% with 8 weeks anaerobic training Bicarbonate and muscle phosphates Delays onset of fatigue