Chapter 4: Developing Strength

Transcription

1 Chapter 4: Developing Strength Objectives Discuss physiological adaptations to strength training Discuss the different types of muscle contractions and their role in strength training Discuss the different types of strength training Muscle Contractions Isometric Contraction that produces tension in the muscle without any change in muscle length Concentric (+) Contraction that produces muscle shortening Biceps curl Eccentric (-) Contraction that produces muscle lengthening Lowering of weight after biceps curl Concentric vs. Eccentric Both are considered dynamic movements Concentric contractions accelerate movement Eccentric contractions decelerate movement Greater force produced by eccentric contractions Injury more commonly associated with eccentric contractions Eccentric contractions should be included in all training and rehab programs Muscle Fiber Type Slow twitch (Type I): Fast twitch (Type II) Bench press Shoulder press Identify the concentric and eccentric phases of the lifts above. 1

2 Fast Twitch vs. Slow Twitch Slow twitch (Type I): Fatigue resistant Time necessary to produce force is greater Long duration, aerobic type activities Generally major constituent of postural muscles Fast Twitch vs. Slow Twitch Fast twitch (Type II) Fatigue Anaerobic in nature High force in short amount of time Produce powerful movements A vs. B Fast Twitch vs. Slow Twitch Individual make-up Muscles contain both types of fibers Muscle functioning impacts ratios (postural vs. powerful movement) Genetically determined Metabolic capabilities can change in response to training Factors that Determine Levels of Muscular Strength Hypertrophy vs. Atrophy Size of muscle: function of diameter and number of fibers Neuromuscular efficiency Biomechanical factors Overtraining (psychologically, physiologically) Reversibility Physiology of Strength Development Three theories of muscle hypertrophy: Increase in number of fibers Infusion of blood - transient hypertrophy Increase in protein myofilament number and size PROVEN Physiology of Strength Development Other enhancements due to training Increased noncontractile tissue strength, bone mineral content, aerobic/anaerobic enzymes, enhanced oxygen uptake 2

3 Techniques of Resistance Isometric exercise Progressive resistance exercise (PRE) Techniques of Resistance Overload principle must be applied Must work muscle at increasingly higher intensities to enhance strength over time If intensity of training does not increase, but training continues, muscle strength will be sustained Overload Principle Activity must be increased and upgraded constantly in order to gain a higher response from the body Work at or near maximum capacity Applicable to conditioning and training Isometric Contraction where muscle length remains unchanged Muscle contraction that lasts 10 seconds and should be perform 5-10 times/daily Pro: quick, effective, cheap, good for rehab Con: only works at one point in ROM, produces spiking of blood pressure due to Valsalva maneuver Isotonic training Constant (fixed) resistance Variable speed Isokinetic training Variable resistance Constant (fixed) velocity or speed Isotonic Concentric & eccentric contractions Various types of equipment can be utilized (Free weights, machine weights) Spotter is necessary for free weight training to prevent injury, motivate partner and instruct on technique 3

4 Isokinetic Maximal effort = Maximal strength gains Disadvantages Cost Need for maximal effort/motivation Used often in rehab setting Safe, controlled Capable of providing data on improvement Principles of PRE Concentric and eccentric training should be incorporated for greatest strength improvement Concentric phase of lift should last 1-2 seconds, eccentric phase 2-4 seconds Variations exist between free and machine weight lifting motion restrictions levels of muscular control required amount of weight that can be lifted Exercise When training, should be able to perform 3 sets of 6-8 repetitions When training, increases should occur in increments of 10% 1 RM can be utilized measure maximum amount of weight that can be lifted - must be very careful of a particular muscle group should occur 3-4 times per week (not on successive days) Free weights vs. machine weights Advantages Disadvantages Muscular Endurance vs. Strength for endurance enhances strength and vice versa for strength should involve lower repetitions at heavier weight for endurance requires lower weight at repetitions 4

5 What questions do you have? 5