Lecture 5 Kin PDF - Muscular Strength Training

2024-10-28 Muscular Strength: Training muscles to become stronger Monday October 28, 2024 0 Lecture Objectives Describe four standard method...

2024-10-28 Muscular Strength: Training muscles to become stronger Monday October 28, 2024 0 Lecture Objectives Describe four standard methods to assess muscular strength, Identify how to train muscle to become stronger: describe optimum sets and repetitions, frequency, and relative intensity for progressive resistance training, Understand the adaptations that occur in response to strength training. 1 1 Click to add footer 1  2024-10-28 Case Study Anthony, a 64 year old physician, comes to you for a strength training program. He has been inactive since the COVID pandemic - he did not want to go to the gym due to fear of getting sick. He says he walks all day long (he works in a hospital) so he only really needs a strength training program. Where do you start? 2 2 Anthony’s Path? 3 3 Click to add footer 2  2024-10-28 Assessing Muscle Strength Cable tensiometry; dynamometry; 1-RM; Computer assisted; 4 4 Muscle Strength Measurement Muscle strength represents the maximum force or tension output generated by a muscle or related muscle groups Can be measured by: Cable tensiometry Dynamometry One-repetition maximum Computer-assisted, electromechanical, and isokinetic methods 5 Click to add footer 3  2024-10-28 Cable Tensiometry Increasing force on cable depresses riser over which the cable passes Deflects pointer and indicates subject’s strength score Measures muscle force in a static or isometric muscle action that elicits little or no change in the muscle’s 6 external length 6 One-Repetition Maximum Maximum amount of weight lifted one time using proper form during a standard weightlifting movement Difficult to estimate initial weight Weight progressively added until person reaches maximum lift capacity Weight increments range between 1 and 5 kg/2.2 and 11 lb Rest interval between lifts important 7 7 Click to add footer 4  2024-10-28 Dynamometry External force applied to dynamometer compresses a steel spring and moves a pointer. The force required to move the pointer a given distance determines applied external force. 8 How to estimate 1-RM Weight lifted for 7 to 10-RM = 68% of 1-RM for untrained and 79% for trained Equations to predict 1-RM weight from 7 to 10-RM weight Untrained: 1-RM (kg) = 1.554 × 7 to 10-RM (kg) – 5.181 Trained: 1-RM (kg) = 1.172 × 7 to 10-RM (kg) – 7.704 9 9 Click to add footer 5  2024-10-28 Computer-Assisted, Electromechanical, and Isokinetic Methods Force platforms measure the external application of muscle force by a limb, as in jumping. Other electromechanical devices assess forces generated during all phases of an activity (e.g., cycling) or primarily arm (supine bench press) or leg (leg press) movements. Isokinetic dynamometer contains a speed-controlling mechanism that accelerates to a preset, constant velocity with force application. Measures maximum force generated throughout the full ROM at a pre- established velocities. 10 10 Isokinetic Electromechanical Dynamometer 11 11 Click to add footer 6  2024-10-28 Strength-Testing Considerations Require standardized instructions prior to testing. Ensure uniformity in duration/intensity of warm-up Provide adequate practice prior to testing to minimize “learning” effect. Ensure consistency among subjects in angle of limb measurement and/or body position on device. Predetermine a minimum trial number (repetitions) to establish a criterion strength score. Select test measures with high reproducibility. Recognize individual differences in body size and composition when 12 evaluating strength. 12 Learning Factors Affect Strength Measures 13 13 Click to add footer 7  2024-10-28 Difference in Maximum Weight Lifted Between Gender 14 14 Training Muscle to Become Stronger Progressive resistance exercise; Periodization; Isometric Strength Training; Isokinetic Resistance Training; Plyometric Training 15 Click to add footer 8  2024-10-28 Resistance Training Equipment Categories Free weights, kettlebells, and barbells, common weightlifting equipment Isokinetic, air pressure, and hydraulic equipment that provides constant speed and variable resistance Cam devices and concentric–eccentric apparatus 16 16 Training Muscles to Become Stronger A muscle strengthens when trained near its current maximum force- generating capacity. Overload intensity, not type of exercise that applies overload, governs strength improvements. Types of overload applications Progressive-resistance weight training Isometric training Isokinetic training 17 17 Click to add footer 9  2024-10-28 Different Muscle Actions Dynamic action produces movement of bones (i.e., upper or lower limb or trunk) Concentric: occurs when muscle shortens and joint movement occurs as tension develops Eccentric: occurs when external resistance exceeds muscle force and muscle lengthens while developing tension Static action involves muscle activation without observable change in muscle fiber length Isometric: occurs when muscle generates force and attempts to shorten but cannot overcome external resistance 18 18 Concentric, Eccentric and Isometric Actions 19 19 Click to add footer 10  2024-10-28 Resistance Training Most popular form involves raising and lowering an external weight. Weight lifted remains constant. Dynamic constant external resistance (DCER) Barbell Dumbbell Weight plates on a pulley- or cam-type machine. 20 20 Progressive Resistance Exercise (PRE) Novice - 8 to 12-RM, Intermediate - 1 to 12-RM, Advanced- 1 to 6-RM Rest 3 min between sets Increase load 2 to 10% when individual performs 1 to 2 repetitions above current workload 1-set vs 2 to 3 sets ? 21 21 Click to add footer 11  2024-10-28 Progressive Resistance Exercise (PRE) (cont.) Novices and intermediates should train 2 to 3x/wk; advanced can train 3 to 4x/wk. If training includes multiple exercises, 4 to 5x/wk may produce less improvement than training 2 to 3x/wk. Inadequate recovery retards progress in neuromuscular and structural adaptations and subsequent strength development. A fast rate of moving resistance generates more strength improvement 22 than moving at a slower rate. 22 Progressive Resistance Exercise (PRE) (cont.) Engage large before small muscle groups, multiple-joint exercises before single-joint exercises, and higher-intensity exercise before lower-intensity exercise. Power training should include lighter loads performed at fast contraction velocity. In power training, use 2- to 3-min rest intervals between sets. 23 23 Click to add footer 12  2024-10-28 Periodization Subdivides a macrocycle into mesocycles, with each mesocycle separated into weekly microcycles. Progressively decreases volume and increases intensity to maximize strength/power gains Phases: Preparation phase: high-volume, low-intensity First transition phase: moderate volume, moderate intensity Competition phase: low-volume, high-intensity Second transition phase: active recovery 24 24 Periodization subdivisions 25 25 Click to add footer 13  2024-10-28 Isometric Strength Training Benefits: Provides muscle overload Improves strength Detects muscle weakness at specific angles in ROM Limitations: Poor application for functional sports training Cannot evaluate overload level or training progress High degree of specificity 26 Time consuming 26 Isometric Training Response Specificity Training in movements that mimic required force–capacity improvement Strength improvement blends two factors: Neural organization and excitability of motor units power discrete patterns of voluntary movement Muscle fiber and connective tissue components 27 27 Click to add footer 14  2024-10-28 Muscle Force-Generating Capacity Varies with Joint Angle 28 28 Isokinetic Resistance Training Overload muscle at a preset constant speed so muscles fully mobilize force-generating capacity throughout full ROM, Effort during exercise movement encounters an opposing force to that applied by the isokinetic mechanical device, With an isokinetically loaded muscle, desired movement speed occurs almost instantaneously while generating the muscle’s peak power output throughout the ROM. 29 29 Click to add footer 15  2024-10-28 Plyometric Training Various jumps in place or rebound jumping to mobilize inherent stretch–recoil characteristics of skeletal muscle and its modulation via the stretch (myotatic) reflex, Involves rapid stretching followed by muscle-shortening during dynamic movements, Plyometric actions overloads muscles, facilitating increases in strength and power. 30 30 Plyometric Training Examples 31 31 Click to add footer 16  2024-10-28 Body Weight-Loaded (Closed-Kinetic Chain) Training Distal segment bears body weight or part of body weight, Activates both agonist and antagonist muscles about a joint, including other muscles groups along the kinetic chain, 32 32 Core Training/Strenghtening (lumbar, trunk or dynamic. stabilization, core pillar training) The “core” represents a four-sided muscular frame with four components: Abdominal muscles in front Paraspinals and gluteals in back Diaphragm at the top Pelvic floor and hip girdle musculature frames at the bottom Includes 29 pairs of muscles that hold trunk steady, and balances and stabilizes surrounding bony structures 33 33 Click to add footer 17  2024-10-28 Explosive Power Development 34 34 Anthony’s exercise prescription Testing? Exercise training? 35 35 Click to add footer 18  2024-10-28 Adaptations that occur with Strength Training 36 Neural and Muscular Adaptations Impact Strength Improvements Neural adaptations predominate in the early training phase. Adaptive alterations in nervous system function that elevate motor neuron output account for rapid and large strength increases early in training, without increases in muscle size and cross-sectional area. Hypertrophy-induced adaptations place the upper limit on longer-term training improvements. 37 Click to add footer 19  2024-10-28 Neural and Muscular Adaptations in Strength Improvement 38 Training Impact on Neuromuscular Junction Nerve conduction velocity (NVC) is faster in the arms than in the legs, and tapered distal nerve segments conduct more slowly than proximal segments because they are cooler than proximal regions. EMG detects neuromuscular abnormalities following a nerve’s stimulation to a targeted muscle or muscle groups. EMG and NCV tests help to detect the presence, location, and extent in nerve and/or muscle dysfunction. 39 39 Click to add footer 20  2024-10-28 Changes in Muscle Fiber Size That Accompany Training-Induced Hypertrophy 40 40 Hypertrophy Increase in muscular tension (force) with training provides main stimulus to initiate muscle growth. Hypertrophy reflects biologic adaptation to increased workload independent of gender/age. Overload training enlarges individual fibers with subsequent muscle growth. Changes in muscle size become detectable after only 3 wk of training. Remodeling of muscle architecture precedes gains in muscle cross- sectional area. 41 Click to add footer 21  2024-10-28 Metabolic Adaptations Strength training enhances anaerobic and aerobic energy transfer capacity of both fiber types. Heightened oxidative capacity of fast-twitch fibers with endurance training brings them to a level nearly equal to the aerobic capacity of the slow-twitch fibers of untrained counterparts. Metabolic characteristics of specific fibers and fiber subdivisions undergo modification within 4 to 8 wk of training. 42 42 Fast- and Slow-Twitch Muscle Fiber Ratios 43 43 Click to add footer 22  2024-10-28 Muscle Cell Remodeling Skeletal muscles represent dynamic tissues. Muscle fibers undergo regeneration and remodeling to alter their phenotypic profile. Activation of muscle via specific types and intensities of long-term use stimulates otherwise dormant myogenic stem cells situated under a muscle fiber’s basement membrane; these proliferate and differentiate to form new fibers. Muscle fiber–type transformations occur with specific-type training. 44 44 Model for Skeletal Muscle Adaptations 45 45 Click to add footer 23  2024-10-28 Muscle Plasticity 46 46 Muscle Hyperplasia: Are New Muscle Fibers Created? In animals, new fibers develop from satellite cells or by longitudinal splitting under stress, neuromuscular disease, or muscle injury. Some evidence supports hyperplasia in humans yet enlargement of existing individual muscle fibers represents the greatest contribution to increased muscle size from overload training. 47 47 Click to add footer 24  2024-10-28 Changes in Muscle Fiber Type with Resistance Training Biopsy data show no change in percentage distribution of fast- and slow-twitch fibers with resistance training. Months of resistance training in adults does not alter basic skeletal muscle fiber composition. 48 48 Muscle Hypertrophy in Men and Women The absolute amount of muscle hypertrophy with resistance training represents a primary gender difference. Men experience a greater absolute change in muscle size from their larger initial muscle mass. Muscular enlargement on a percentage basis remains similar between genders. Gender-related differences in hormonal response to resistance exercise may determine any ultimate gender differences in muscle size and strength adaptations with prolonged training. 49 49 Click to add footer 25  2024-10-28 Special Considerations 5 0 50 Resistance Training Guidelines for Health Enhancement and Disease Prevention Competitive athletes Optimize muscular strength, power, and hypertrophy with high intensity 1-RM to 6-RM Middle-aged and older adults Focus on maintenance of muscle and bone mass and muscular strength and muscular endurance to enhance overall health and physical-fitness Moderate intensity 8-15 RM; 2× week 51 51 Click to add footer 26  2024-10-28 Resistance Training for Children Supervised resistance training using concentric-only muscle actions with relatively high repetitions and low resistance, Concerns for potential injury from excessive musculoskeletal loading include epiphyseal fractures, ruptured intervertebral disks, lower back bony disruptions, and acute back trauma. 52 52 Does Resistance Training Plus Aerobic Training Equal Less Strength Improvement? Combining different modes of exercise may induce antagonistic molecular level, intracellular signaling mechanisms that could negatively impact, Added energy (and perhaps protein) demands of aerobic training limit a muscle’s growth and metabolic responsiveness to resistance training muscle’s adaptive response to resistance training, Aerobic training may also inhibit signaling to the muscles’ protein- 53 synthesis machinery 53 Click to add footer 27  2024-10-28 Factors That Interact to Develop and Maintain Muscle Mass 54 54 Resistance Training and Metabolic Stress Resistance training produces no improvement in VO2max or submaximal exercise HR and SV. Lack of cardiovascular improvement probably results from the relatively low “whole body” metabolic and circulatory demands and high anaerobic metabolic requirements of resistance training. Light-to-moderate HR response (≤130 b·min−1) occurs with 8- to 10- RM weightlifting exercises, and elicits an energy expenditure of only 3 to 4 METs. 55 55 Click to add footer 28  2024-10-28 Detraining Effects on Muscle Limited data document that muscle strength decrements and associated factors with cessation of resistance training conclude that: Discontinuing training for 2 wk caused male power lifters to lose 12% of their isokinetic eccentric muscle strength and 6.4% of their type II muscle fiber area, without loss in type I fiber area. Reducing training frequency to 1 to 2 weekly sessions provides sufficient stimulus to maintain training-induced strength gains 56 56 Circuit Resistance Training (CRT) Deemphasizes brief intervals of heavy, local-muscle overload in standard resistance training in favor of more prolonged submaximal effort Provides more general conditioning that improves body composition, muscular strength and endurance, and cardiovascular fitness A person lifts a weight between 40 to 55% of 1-RM as many times as possible with good form for 30 s After a 15-s rest, person moves to next exercise station and so on to complete the circuit, usually composed of 8 to 57 15 stations. 57 Click to add footer 29  2024-10-28 Delayed Onset Muscle Soreness and Stiffness Occurs following extended layoffs or with unaccustomed exercise Appears later and can last for 3 to 4 days; termed delayed-onset muscle soreness or DOMS Factors that can produce DOMS Minute tears in muscle tissue Osmotic pressure changes Muscle spasms Overstretching and tearing of portions of connective tissue harness Acute inflammation 58 Alteration in the cell's calcium regulation 58 Delayed-Onset Muscle Soreness (DOMS) Eccentric muscle actions induce greater DOMS than concentric-only or isometric actions, particularly in older adults. Existing muscle damage or soreness from previous activity does not exacerbate subsequent muscle damage or impair the repair process. The body initiates a series of adaptive cellular events to unaccustomed exercise that produces DOMS. Alterations in sarcoplasmic reticulum structure and function with unaccustomed physical activity can cause alterations in pH, intramuscular high-energy phosphates, ionic balance, temperature 59 59 Click to add footer 30  2024-10-28 Phases in DOMS Development and Healing: 60 60 Muscle Soreness Ratings 61 61 Click to add footer 31  2024-10-28 Questions? 62 Click to add footer 32