PHYG 16693 Adaptations to Exercise Training PDF

Module 2: Adaptations to Exercise Training  Learning Objectives Define muscular strength, power, and endurance. Examine strength training principles. Examine how strength is gained through resistance training. Note changes in the muscle structure and in the neural mechanisms controllin...

Module 2: Adaptations to Exercise Training  Learning Objectives Define muscular strength, power, and endurance. Examine strength training principles. Examine how strength is gained through resistance training. Note changes in the muscle structure and in the neural mechanisms controlling the muscle that occur during resistance training. Learn what causes muscle soreness and how to prevent it. Find out if there are strength training differences between women and men and between younger and older persons. 2 Defining Muscular Performance - Strength The maximal force that can be generated by a muscle or muscle group in a single contraction (1-RM or 1 Repetition Maximum). - Muscle specific - Directly associated with muscular endurance - With  in muscle strength , there is a corresponding ↑ in muscle endurance. 3 Force Generation The ability of a muscle or muscle group to generate force depends on:  Size of muscle  Type of muscle contraction  # of muscle fibres activated  Ability of nervous system to activate fibres  Motivation of the person  Strength potential is limited by genetics # of fast twitch fibres 4 Evaluating Strength 1- Repetition Max (1-RM) - A functional test of the maximum weight that can be lifted in one complete repetition (with proper technique) Isokinetic 1-RM: isokinetic machine Eccentric 1-RM: special apparatus to measure force during muscle elongation Isotonic 1-RM: machine or free weights Research found a strong positive correlation among isotonic, eccentric, and isokinetic strength measurements (r = 0.78, p < 0.05) (refer to next slide for explanation of r, R2, and p values) 5  Correlations Strong Relationship: r + 0.7 and + 0.99 equivalent to R2 of 0.49 to 0.98 Moderate Relationship: r + 0.69 and + 0.40 R2 of 0.48 to 0.16 Weak Relationship: r + 0.39 and + 0.10 R2 of 0.15 to 0.01 No Relationship: r + 0.099 and 0 R2 of 0.0098 to 0 r values indicate a relationship between 2 variables (x and y axis), which can be positive or negative and are from + 1.0 to -1.0. R2 gives the proportion of the variance (fluctuation) of one variable that is predictable from the other variable and represents the percentage of the data that is closest to the line of best fit on a graph. For example, if r = 0.922, then R 2 = 0.850, which means that 85% of the total variation can be explained by the linear relationship between x and y. The other 15% of the total variation remains unexplained. p value of < 0.05 significant p value of > 0.05 not significant, due to chance 6  Predicting 1-RM for Exercise Prescription Since muscular strength is directly related to muscular endurance, 1-RM can be predicted without performing a maximal lift Usually a 6 to 10-RM test 1. “Guess” at 1-RM (estimated 1-RM) 2. Warm up at 40 – 60% 1-RM for 5 – 10 reps 3. Stretch during a 1-minute rest period 4. Perform 1 set of repetitions at 60 – 80% of estimated 1-RM 5. If > 10 reps, rest for 3-5 minutes, increase weight until only 6 – 10 reps can be performed 6. Calculate 1-RM from chart (next slide) 7  Predicted 1-RM Calculation Determine % 1-RM from Reps Completed % 1-RM # of reps completed 1 100 Divide weight lifted by % 2 95 1-RM 3 93 Example 4 90 Client performed 8 reps 5 87 of 100lbs on the bench 6 85 press 7 83 8 reps = 80% 1-RM 8 80 9 77 1-RM = 100 lbs lifted 10 75 0.80 1 RM = 125 lbs 8  Example: Predicted 1-RM Calculation Bench Press: Individual Reps Completed % 1-RM performed 10 reps of 90 lbs 1 100 Leg Press: Individual 2 95 performed 6 reps of 240 lbs 3 93 4 90 Calculate the 1-RM for the: 5 87 6 85 7 83 Bench Press ___________ 8 80 9 77 Leg Press _____________ 10 75 9  Defining Muscular Performance: Muscular Endurance The body’s ability to sustain repeated muscle actions or a single static contraction. Can be improved by: i) Using a moderated load ii) ↑ the # of reps A muscle that fatigues rapidly has a low endurance capacity. Women often outperform men on endurance tests, esp at the lower workloads 10  Evaluating Muscular Endurance: Tests 1. performed repeated contractions - partial curl ups, push ups 2. sustain a contraction - Isometric – hang and hold on chin up bar - back extension test 3. dynamic endurance tests Partial curl up to a set cadence (metronome) Lifting a set weight (eg. 50 lbs) to a set cadence 4. relative load endurance test - subjects are assigned a fixed % of their maximum strength, eg. 20%, 50%, 75% of 1RM - They are timed for their ability to endure a given lifting cadence in dynamic or isometric test 11  Defining Muscular Performance – Muscular Power The product of strength and the speed of movement. If two individuals can lift the same amount of weight, the one that can lift it faster is generating more power than the other.  Power = force x distance / time (strength) (speed or velocity) 12 What fibre type is best for power athletes? ______  Muscular Power  The peak power generated by a muscle increases with increasing force and velocities of movement to a maximum region,  after that point, power will decrease due to a reduction in force at faster movements. This is an inverted U relationship between a muscle’s maximal power output and its velocity (speed of movement). 13  Power: inverted U relationship Example: cycling – gearing down to get up a hill - If you don’t gear down - – no speed because there is too much resistance to get up the hill - If you gear down too much - – pedaling too fast because there is little or no resistance, therefore no power to get up the hill - Lab #2 will demonstrate this concept 14  Aerobic and Anaerobic Power Aerobic Power:  Oxygenconsumption – measuring CV fitness  Maximum Aerobic Power – Max VO2 test Anaerobic Power:  Body’sability to produce ATP without oxygen  Wingate Bike Test 15 Basic Strength Training Principles 16  1.) Progressive Resistance Overload Principle Increase the load gradually as the body adapts to the new stress 5% weight increment for  resistance To train for strength, emphasis is on higher resistance (high intensity) and lower reps For endurance, lower resistance, higher reps Most important strength training principle 17  1.) Progressive Resistance Overload Principle 2 important concepts: i) Overload i) muscles must be overloaded beyond the point to which they are normally loaded in order to gain strength ii) Progressive resistance training - implies that as the muscle gets stronger, a greater resistance is required to stimulate further increases in strength eg. Lifting 50 lbs at 10 reps after a couple of weeks, the individual can perform 15 reps next training session, increase the resistance 2.5 lbs (52.5 lbs or 5%), now the individual can only lift the weight 8 reps 18 2.) Stress – Rest Principle or Principle of Hard/Easy One day of exercise followed by one day of rest Or, one day of high intensity training (hard), followed by easy day of training If a person trains for too long, the body will fail to heal If a person has too much rest, there will be no improvement 48 hrs rest between each muscle group workout 19  3.) Principle of Symmetry The overall balanced development of the body. An overall conditioned participant will achieve greater results than someone with only specific development. 20  4.) Principle of Specificity (SAID Principle) S: Specific A: Adaptations to I: Imposed D: Demands Training adaptations are highly specific to the: i) Type of activity ii) The volume and intensity of the exercise performed The training program must stress the physiological systems that are critical for optimal performance in the given sport in order to achieve training adaptations. Eg. To improve muscular power, the high jumper would not emphasize distance running or endurance resistance training 21 5.) Contraction Control Principle Both raising and lowering a weight should be performed in a slow, controlled manner Guideline: 2 to 4 seconds in each movement 22  6.) Ceiling Principle As fitness level increases, strength and endurance will also increase. As you reach your potential limit, increases become smaller 23  7.) Principle of Reversibility “Use it or lose it” You will lose benefits of training at a ratio of 1:3. Example Training hard for 1 month Broke your leg, no training After 3 months, the training effect will be back to the start of training 24 8.) FITT Principle Frequency: days/week Intensity: % 1-RM Time: repetitions, sets Type: specific exercises, equipment, athletes (sport specific) 25  8.) FITT Principle (eg. Start of program) Muscular Strength F: 2 – 3 days/wk I: 50 – 69% of 1-RM (moderate intensity) T: 1 - 2 sets, 8 – 10 exercises (large muscle groups) 8 – 12 reps T: ----------specific to sport-------------- Progression:  increase resistance every 1 – 2 weeks, approximately 5% (to allow for adaptation) 26  8.) FITT Principle: Exercise Order At least 1 exercise per major muscle group Usually recommend large muscle groups 1st Alternate agonist/antagonist exercises Alternate upper body/lower body exercises to maximize recovery  Advanced lifters may split routines (eg. Upper body one day, lower body next day) 27  9.) Maintenance Principle Once a training effect has been reached, it will be maintained by keeping: intensity levels the same duration the same training frequency the same or slightly reducing it. Side Note: Once your goals for strength development have been achieved, you can reduce training frequency, intensity, or time and still prevent losses in strength gained for at least 12 weeks. ……However, you must continue training with a resistance maintenance program that still provides sufficient stress to the muscles. 28  10.) Principle of Individuality Individuals are unlikely to show precisely the same adaptations to a given training program Therefore, each training program must be tailored to each individual 29  11.) Principle of Variation or Periodization Gradual cycling of specificity, intensity, and volume of training to achieve peak performance in a competition and to prevent over-training Macrocycles (monthlong training cycles) Mesocycles (weekly training cycles) Microcycles (cycle lasting a few days) Individual workouts 30 If an individual follows the training principles, resistance training programs can produce a 25% to 100% improvement in strength within 3 to 6 months. These adaptations to resistance training is similar when comparing - males and females, - children and adults, - younger and older adults However, females, children, older adults, in general have less strength relative to body weight and size compared to male adults 31 Review: Designing Resistance Training Programs: Things to Decide 1. Exercises that will be performed 2. Order in which they will be performed 3. Number of sets for each exercise 4. Rest periods between sets and exercises 5. Intensity (amount of resistance), number of repetitions, and velocity of movement 32 Types of Resistance Training: Review Static-contraction resistance training (isometric) Free weights (concentric) Eccentric training (lengthening) Variable-resistance training Machine (cam) Isokinetic training Plyometrics (uses the stretch reflex to recruit more motor units (eccentric and concentric) Electrical muscle stimulation training (used during rehab) 33 Resistance Training Programs Key Points Low-repetition, high-resistance training enhances ________________ development High-repetition, low-resistance training optimizes_____________________________ _______________________ is important to prevent overtraining (continued) 34 Resistance Training Programs (continued) Key Points Resistance training uses __________ or ______________ contractions ___________________ training appears to be essential to maximizing hypertrophy ______________________________can be successfully used in rehabilitating athletes 35 Adaptations to Resistance Training 36  Muscle Size and Strength  Muscle strength involves more than just muscle size.  Neural control or motor unit recruitment also plays a role in muscle strength.  Early gains in strength appear to be more influenced by neural adaptations (first 8 – 10 weeks). Long-term strength increases are largely the result of muscle fiber hypertrophy (main stimulus) and cellular adaptations (10 weeks and greater). Usually takes 8 – 12 weeks of training to see significant strength gains. Females experience similar strength gains compared with males, but women do not experience as much hypertrophy. 37 As weight classification increases (implying muscle strength), so does total weight lifted for world records in the snatch, and clean and jerk lifts. 38  Mechanisms of Gains in Muscle Strength from Resistance Training 1. Neural Control of Strength Gains i) Synchronization and recruitment of additional motor units ii) Increased frequency of discharge (or rate coding) of motor units iii) Autogenic inhibition iv) Reduction in coactivation of agonist and antagonist muscles 2. Muscle Hypertrophy 39  Mechanisms of Gains in Muscle Strength from Resistance Training 1. Neural Control of Strength Gains i) Synchronization and recruitment of additional motor units - motor units are generally not recruited at the same time -Strength gains may result from changes in the connections between motor neurons located in the spinal cord, allowing motor units to act more synchronously, increasing the muscle’s ability to generate force -Another possibility for increase in strength is simply more motor units are recruited 40  Mechanisms of Gains in Muscle Strength from Resistance Training 1. Neural Control of Strength Gains ii) Increased frequency of discharge (or rate coding) of motor units - with more motor units recruited, frequency can increase, therefore producing more force 41  Mechanisms of Gains in Muscle Strength from Resistance Training 1. Neural Control of Strength Gains iii) Autogenic inhibition when tension on a muscle’s tendons exceed the threshold of the Golgi tendon organs, motor neurons to that muscle are inhibited (to prevent damage to the muscle) – this is called autogenic inhibition strength training may reduce or counteract the inhibitory impulses, allowing the muscle to increase strength 42  Mechanisms of Gains in Muscle Strength from Resistance Training 1. Neural Control of Strength Gains iv) Reduction in coactivation of agonist and antagonist muscles if both agonist and antagonist muscles would contract equally, there would be no movement strength training may reduce the coactivation of the antagonist muscle, therefore increase strength of the agonist muscle 43  2. Muscle Hypertrophy Transient—”pumping up” of muscle during a single exercise bout due to fluid accumulation from the blood plasma into the interstitial spaces of the muscle. Chronic—increase of muscle size after long-term resistance training due to changes in: - muscle fiber number (fiber hyperplasia) or - muscle fiber size (fiber hypertrophy ). 44  Fibre Hypertrophy (size)  Increased # and size of myofibrils per muscle fibre  Increased amount of contractile protein – actin and myosin, resulting in more cross-bridges  Increased amounts and strength of connective tissue  Increase in sarcoplasm (↑ glycogen, ↑ myoglobin -↑ O2 available for the muscles) w Muscle protein synthesis increases during the postexercise period. (protein synthesis ↓ during exercise because it’s being utilized) w Testosterone plays a role in promoting muscle growth. w Training at higher intensities appears to cause greater fiber hypertrophy than training at lower intensities. 45 FIBER HYPERTROPHY following 6 months of resistance strength training in a previously sedentary male. Before training Larger fibres after 6 months of training 46 Relationship between the strength of the arm flexor muscles and their cross-sectional area in both M and F. Arm Flexor Strength (kg) What does this graph represent? 0 5 10 15 20 25 Cross-sectional area (cm2) 47  Fiber Hyperplasia (muscle fibre splitting) w It has been proposed that muscle fibers can split in half with intense weight training (longitudinal fibre splitting) w Each half then increases to the size of the parent fiber.  It has been shown to occur in animal models  Only a few studies indirectly suggest that hyperplasia occurs in humans and is still controversial 48  High resistance training can result in longitudinal fibre muscle splitting in cats. Control, no resistance Resistance Training, Low Resistance Resistance Training, High Resistance Cats were trained to move a lever with 0 5 10 15 20 resistance to get their food (generate Increase in # of muscle fibres (%) force), 5 days per week, 34 weeks 49  Muscle Atrophy and Decreased Strength with Inactivity Decrease in muscle size Decrease in muscle protein synthesis Rapid strength loss Why would a muscle atrophy? Immobilization Stopped training Reduced training Not enough food energy 50 DECREASE IN STRENGTH AFTER INJURY What is most important in strength losses following injury? E-C coupling failure seems to be most important in strength losses following injury E-C Coupling or excitation- contraction coupling: the process whereby electrical signals at the muscle membrane leads to muscle contraction 51  Muscle Atrophy due to Immobilization Muscle suddenly becomes inactive In the first 6 hours, protein synthesis starts to decrease (start of atrophy) Strength decreases about 3 – 4 % per day in the first week (due to atrophy and decrease in neuromuscular activity to the muscle) 52 Muscle Atrophy due to Cessation of Training in Women Pre-20: Strength before 20 weeks of resistance training Post-20: changes following 20 weeks of training Pre-6: changes following 30-32 weeks of detraining Post-6: changes following 6 weeks of retraining 53  Changes in mean cross-sectional areas for fibre types with resistance training in women over periods of training and detraining (same study as previous slide) Pre-20: Strength before training Post-20: changes following 20 weeks of training Pre-6: changes following detraining (30-32 weeks) Post-6: changes following 6 weeks of retraining - During the 2 training periods, ↑ in strength were accompanied by ↑ in the cross- sectional area of all fiber types and a ↓ in the percentage of Type IIx fibres - Detraining had little effect on ST fibres but decreased FT fibre areas CONCLUSION: maintenance programs are necessary to prevent strength losses 54  Muscle Soreness 2 types of muscle soreness: 1. Acute 2. Delayed (DOMS) 55  Acute Muscle Soreness Occurs during the latter stages of exercise and immediately following the exercise period Thought to be associated with a lack of blood flow (ischemia) to the working muscles Because of ischemia, metabolic waste products (lactic acid, potassium) cannot be removed and thus accumulate to the point of stimulating the pain receptors located in the muscles Usually disappears once intensity of contraction is reduced or within minutes or hours after exercise has stopped (because blood flow is restored and waste products can be removed). 56  Delayed Onset Muscle Soreness Is felt 12 to 48 hours after a strenuous bout of exercise Results primarily from eccentric action (due to stress placed on tendons and muscle)  May be caused by inflammatory reaction inside damaged muscles  May be due to tissue edema (accumulation of fluid) inside the muscle compartment.  May be caused by torn muscle fibres and/or damage to connective tissue 57 Delayed muscle soreness is most pronounced following eccentric contractions. 3 2.5 Muscular Soreness 2 (rating units) Eccentric 1.5 Isotonic Isometric 1 0.5 0 0 24 48 72 Time (hours) 58 MUSCLE FIBERS AFTER A MARATHON Disruption (damage) of the cell membrane in one of the cell membranes. 59 MUSCLE BIOPSY SAMPLE TAKEN BEFORE AND AFTER A MARATHON Normal arrangement of the actin Z disk streaming caused by the and myosin filaments and Z disk. eccentric actions of running. 60 DOMS and Performance w DOMS causes a reduction in the force-generating capacity of muscles due to physical disruption of the muscle, failure in the excitation-contraction coupling process, and loss of contractile protein w Maximal force-generating capacity returns after days or weeks  Muscle glycogen synthesis is impaired with DOMs  Muscle soreness can hinder performance. 61  Reducing Muscle Soreness w Reduce eccentric component of muscle action during early training w Start training at a low intensity, increasing gradually w On the other hand, research has also found that by beginning with a high-intensity, exhaustive bout of eccentric-action exercise to cause much soreness initially, can actually decrease future pain. Because the factors associated with DOMS are important in stimulating muscle hypertrophy, DOMS is most likely necessary to maximize the training response. 62 Exercise-Associated Muscle Cramps (EAMCs) often occurs at night while sleeping, during competition or immediately after competition (night-time cramping may or may not be due to exercise)  Due to:  fluid or electrolyte imbalances (associated with high rates of sweating)  sustained  motor neuron activity caused by control at the spinal level brought on by muscle  ↑ muscle spindle activity and ↓ Golgi tendon organ activity (muscle receptor that monitors tension)  Muscle fatigue w Rest, passive stretching, and holding the muscle in the stretched position may be effective treatments w Proper conditioning, stretching, and nutrition are possible prevention strategies. 63  Muscle Soreness and Muscle Cramps: Causes and Occurrences Causes Acute muscle DOMS EAMCs soreness Accumulation of metabolic waste products of exercise Tissue edema Eccentric action in muscle movement emphasized during training Structural damage to muscle cells Inflammatory reactions within muscles Sustained  motor neuron activity caused by control at spinal level brought on by muscle Muscle fatigue Muscle spindle activity ↑ and tendon organ activity ↓ 64  Muscle Soreness and Muscle Cramps: Causes and Occurrences When It Occurs Acute DOMS EAMCs Muscle Soreness During latter stages of exercise bout and during the immediate recovery period A day or two after a strenuous bout of exercise At night while sleeping During height of competition or immediately after competition 65 Designing Resistance Training Programs: Review 1. Consider different dynamic training programs. 2. Perform a training needs analysis. - what muscles need to be trained? - what method of training needs to be used? - what energy system should be stressed? - what are the primary sites of concern for injury prevention 3. Select appropriate resistance levels. 4. Decide on single sets versus multiple sets. 5. Design a training program using periodization. 6. Assign specific forms of resistance training depending on the sport or desired results. 66  Did You Know…? Resistance training can benefit almost everyone, regardless of his or her gender, age, level of athletic involvement, or sport. 67 High resistance strength training increases knee extensor strength in elderly. 9 subjects, ages 87 – 96 years old (mean 90.2 yrs) 8 week resistance training program training quadriceps and hamstring 3 days/week, 3 sets of 8 reps 1st week: 50% of 1RM Weeks 2 – 4: 80% of 1RM Mean  in left knee extensor strength from 7.6kg to 19.3kg (>150% increase) No difference in improvement in M and F Functional mobility (walking) also increased Within 4 weeks of detraining, strength decreased 32% 68