Assessing Muscular Fitness PDF

Chapter 6: Assessing Muscular Fitness Minimum levels of muscular fitness are needed in order to complete ADLs, to maintain independence with age, and to partake in leisurely activities without undue stress or fatigue. Adequate levels of muscular fitness lessen the chance of developing: - Low back pr...

Chapter 6: Assessing Muscular Fitness Minimum levels of muscular fitness are needed in order to complete ADLs, to maintain independence with age, and to partake in leisurely activities without undue stress or fatigue. Adequate levels of muscular fitness lessen the chance of developing: - Low back problems - Osteoporotic fractures - Musculoskeletal injuries ACSM’s (2022) Definition of Muscular Fitness - Muscular fitness refers collectively to characteristics of strength, local muscle endurance, power, and hypertrophy. - Muscular fitness is optimized with resistance training. It encompasses practices such as free weight training, machines, body weight, or objects such as bands which one can use to exert force against a resistance. Muscle endurance - the ability of a muscle group to exert a submaximal force for extended periods. Muscular strength - is the maximal force generated in a single contraction at a specified velocity - is the peak force or torque developed during a maximal voluntary contraction (MVC). Muscular Power - a skill-related component of physical fitness - the muscle’s ability to exert force per unit of time. (Rapidly) - the rate at which mechanical work is performed Types of muscle contraction - Isometric Muscle Action - Muscle length does not change as force is applied - Dynamic muscle action - Muscle length changes as force is applied - Subtypes: - Isotonic - Tension is constant throughout exercise, such as when using free weights - is a misnomer because the tension produced by a muscle group during free weight exercise fluctuates greatly even though the resistance is constant throughout the range of motion (ROM). - Auxotonic - defined as variable muscle tensions caused by changing velocities & joint angles. - is the correct term for describing the muscle action when lifting free weights or performing resistance exercise with a constant resistance exercise machine. - Can be concentric or eccentric - Isokinetic - is a maximal contraction of a muscle group at a constant velocity throughout the entire range of joint motion. - can only be performed on an isokinetic-resistance exercise machine called an isokinetic dynamometer. - Variable resistance - Variable contraction of a muscle through the range of motion against a changing resistance. - Occurs when applying resistance against an elastic band or spring. Concentric muscle action - resistance < force produced by muscle group. - muscle shortens during tension development. Eccentric muscle action - resistance > force produced by muscle group. - muscle lengthens during tension development. - Greater risk of injury Purposes of Strength & Muscular Endurance Assessment - Allows one to establish a baseline before training, allowing for comparison in order to determine progress. - Assess the overall effectiveness or resistance training or exercise rehabilitation programs. Tests that Assess Strength & Muscular Endurance are Specific to the: - Muscle or muscle group being tested - Type of muscle contraction (Isometric or Dynamic) - Velocity of muscle movement (Slow/Fast) - Type of test (Endurance vs Strength) - Equipment used, if any - ROM (if dynamic) Absolute vs Relative muscle strength - Absolute muscle strength - MVC in Newtons or Kg - Relative Muscle strength - MVC/ Body mass Isometric muscle testing - Can be done in multiple ways - Spring-Loaded Dynamometers - Handgrip Dynamometer - Back & Leg Dynamometer - Hydraulic dynamometers Cable Tensiometers Digital Handheld Dynamometer Clinical Methods Load Cells (Strain Gauges) - Isometric muscle testing - measured as the maximum force exerted in a single contraction against an immovable resistance (MVC) - Handgrip strength testing - Uses a spring loaded handgrip dynamometer - An external force applied to the dynamometer compresses a steel spring & moves an indicator needle or pointer. - The force required to move the pointer a given distance determines the external force applied to the dynamometer. - - Handgrip strength is a measure of isometric strength that is often used as an indicator of total body strength. It has been shown to be predictive of functional limitations and disability later in life. It was a stronger predictor of all-cause and cardiovascular mortality than systolic blood pressure in a large longitudinal population study conducted in 17 countries (Leong et al., 2015). Spring-Loaded Back and Leg dynamometers are used for the lower body, back and legs can be isolated with different procedures ( knees bent & back straight / Knees straight & back bent) - Hydraulic dynamometers can be used as an alternative to spring loaded ones - Ex: Jamar handgrip dynamometer - Widely used, good reliability - Gold standard for handgrip dynamometers - Bad resolution means results are not accurate for those with a weak MVC. A Myogrip dynamometer is used for such patients. - Cable tensiometers allow for isometric muscle testing at any angle of a joint’s ROM. - Can be used to assess strength impairment at a specific angle (useful for rehabilitation) - A digital handheld dynamometer is a convenient method for measuring isometric strength. Clinical tests - The following clinical tests have been developed to measure the isometric endurance of core muscles used to stabilize the spine. - V-sit Test (Trunk flexors) - Sorensen Test (Trunk extensors) - Side bridge Test (lateral flexors) Assessment of Dynamic muscular Strength & Endurance - Free weights & Constant Resistance exercise machines - Optimal to test dynamic muscular strength & endurance - A major disadvantage is that the test strength only at the weakest point in the ROM - Variable resistance is not recommended for dynamic muscle testing as it cannot account for fluctuations in muscular force caused by the changing angle (physiological advantage) during the movement. Chapter 7: Designing Resistance Training Programs Resistance training - a systematic program of exercise for the development of the muscular system - Results in increased/maintained: - Muscular endurance - Muscular strength - Muscular hypertrophy - Muscular power - Health benefits include: - Increase in bone density and strength, decreasing the risk of falls with old age. - Increased size and strength of ligaments and tendons - Lowers BP in hypertensive individuals - Decreased fat mass & relative fat mass - Prevents low back syndrome - Terms used when referring to resistance exercise: - Agonist - Prime mover in an action - Activation will induce relaxation in the antagonis - Antagonis - Opposing muscle - Synergist - Muscles that assist the prime mover - Stabilizers - Muscles that prevent unwanted movement Muscle fiber - Composed of myofibrils - Classification of human muscle fiber types: Although the relative composition of muscle fiber type can change in a muscle, a type I cannot change into a type II. - Endurance athletes have a greater % of slow type I fibers. Power related sports (sprinter, olympic weightlifter) require a greater % of fast type IIa/IIx fibers. Resistance training increases muscle strength by hypertrophy of muscle fibers & neuromuscular learning. Resistance training adaptations - First 2-8 weeks - Rapid increase in strength due to neural adaptations - Rate of progression is equal for males & females - 8-10 weeks - Hypertrophy contributes more to progress than neural adaptations, but eventually hypertrophy levels off. - Greater hypertrophy in males due to testosterone - >6 Months - Continued increase in strength without hypertrophy - A secondary phase of neural adaptation is most likely irresponsible for strength increases between 6-12Mo - Hypertrophy does not occur after 12Mo (bet) Hypertrophy - Resistance training results in hypertrophy by increasing - Muscle fiber size - Amount of connective tissue around muscle & muscle fibers Cell content of enzymes & energy storage (ATP + Glycogen) Resistance training increases the size and strength of slow type I and fast type IIa/IIx fibers. Although fast type II fibers are more responsive to a strength stimulus. Muscle learning - Resistance training improves the body’s ability to activate & recruit motor units, leading to an increase of strength with training before hypertrophy occurs. Motor unit - The functional unit of the musculoskeletal system - Composed of one motor neuron and a number of muscle fibers (ranging from 1 to thousands) - When a motor neuron calls upon its fibers, all fibers contract simultaneously and maximally - The number of motor units activated will depend on the amount of force needed - In general, slow type I motor units will activate before fast type IIa/IIx motor units. Steps for developing a resistance exercise training program 1. Identify & structure plan around the primary goal of the individual 2. Determine the type of resistance program to be used - Static, dynamic, or isokinetic 3. Identify muscle weakness based on a fitness assessment 4. Select resistance exercises 5. Order exercises according to the client’s fitness level 6. Determine the appropriate load, set & rep count for each exercise 7. Set guidelines to ensure progressive overload Types of resistance training - Isometric resistance training - Static, no joint movement - Easy as they can be performed anywhere, with little/no equipment. - Disadvantage is that the strength gains are specific to the joint angle trained. It will not strengthen the whole muscle as with dynamic resistance training - Not recommended for hypertensive people or those with a predisposition to coronary issues. - Guidelines: + - Dynamic resistance training - Concentric or eccentric muscle contraction - Require equipment, such as free weights, constant resistance machines, or variable resistance machines - Variables include frequency, intensity, time, type, and exercise order. - Guidelines: - Include 8-10 exercises in program which hits all major muscle groups - Full ROM from a stable position - Inhale during eccentric, exhale during concentric. Do not hold breath unless necessary. - Multiple joint before single joint, large muscles before smaller muscles - Prevent asymmetry by exercising bilaterally - Rest muscle group for 48-72h before exercising them again ASCM (2022) Guidelines for resistance training of healthy adults - Frequency: - Novie: Each muscle group at least 2 non consecutive days of the week - Experienced: frequency is less important than training volume - Intensity: - Muscular fitness: 60-70% RM - Strength: 40-100% RM - Power: 30-60% (Upper body), 0-60% (lower body) - Time: - No set time for training CSEP (2021) Guidelines for Resistance Training of Healthy Adults - Frequency: - Each muscle group should be trained 2-3 non consecutive days of the week - Intensity: - 60-80% RM for most - >80% RM for experienced - 40-50% for the frail - Sets & reps: - 2-4 sets, 8-12 reps for mosty Frequency - Rest muscle groups 48-72h between training - Train 2-3 non consecutive days of the week. (more for experiences) - Routines: - Full body - Split routine Intensity - 60-100% RM optimal for strength development - 60-70% Novice - 70-80% intermediate - 80-100% Advanced Variations for dynamic training - Set variations - Instead of one compound exercise, multiple specific exercise can be done for the muscles involved - Pyramiding: - Light-to-heavy scheme, up to 6 sets - Only recommended for experienced lifters due to large amount of work - Order variation - Pre-exhaustion system, working smaller muscles before larger ones - Alternate exercises to allow one to rest while the other is worked Periodization - A systemic variation of intensity and volume of resistance training - Reserved for experienced lifters, periods can last up to a year. - Used to maximize the response of the neuromuscular system by systematically changing the training or exercise stimulus. Also used to minimize overtraining & injury by planning rest and recovery - Variation may be achieved by changing one of the following stimuli: - Volume - Intensity - Type of muscle contraction - Training frequency - Classic Linear Periodization Model - Macrocycle: 9-12 Mo - Mesocycle: 3-4 Mo - Microcycle: 1-4 weeks - Reverse Linear Periodization Model - Same as Classic linear, but the intensity goes from heavy to light over time. - Undulating periodization model - Heavy to light to Heavy again Circuit Resistance Training (CRT) - A system in which a person is cycling through stations of resistance training with little to no rest in between. - Used to increase strength, muscular endurance, and cardiorespiratory resistance - Super circuit training: Mixing in aerobic exercises. Core stability training - Used to improve functional capacity & sports skills performance for healthy individuals. - A strong core helps maintain the ideal alignment of the neck, spine, scapulae & pelvis while performing exercise. - Develops muscular endurance more than strength or power - Unstable surfaces are often used for training. Eccentric training - Allows training with higher forces and velocities - Used to improve strength, hypertrophy, performance, & aid in tendon & muscle injury rehabilitation. - Methods include - Eccentron – simulates downhill walking or running. - Isokinetic devices – apply an eccentric force. - Weight machines – decrease load during concentric phase & increase load during eccentric phase. - Eccentric cycle ergometers - Increased delayed onset muscle soreness (DOMS) compared to concentric training. Functional training Functional exercise progressions develo[ the strength & function of all muscle groups. - Has been widely used for rehabilitation purposes to improve: - Joint stability - Neuromuscular control - Flexibility - Muscular strength & endurance Extreme Conditioning Programs - High intensity functional training - high-intensity & high-volume activities with short recovery periods: - Crossfit - Insanity - P90X - emphasis on multi-joint exercises, functional movements, body resistance, & variety to target multiple joint angles. Isokinetic Resistance Training - involves dynamic concentric (shortening) muscle actions of a muscle group against an accommodating resistance that matches the force produced by the muscle group throughout the entire ROM - Requires an isokinetic dynamometer that keeps the movement speed constant - Used to increase muscular strength, muscular endurance, muscular endurance. - Advantage: - Little or no muscle soreness because muscles do not contract eccentrically Disadvantage: - Not the best choice if the goal is to increase muscle size as eccentric muscle action performed at a fast velocity is the most effective method for muscle hypertrophy Chapter 8: Assessing Body Composition; Part 1 Fat mass (FM) - Fats that can be extracted from the fat tissues & other tissues in the body - Estimated FM = % Body Fat x Total Body Weight Fat-Free Mass (FFM) - All fat-free tissues in the body, including water, muscle, bone, minerals, connective tissue, & internal organs - Estimated FFM = Total Body Weight – FM Lean body mass (LBM) - contains the small percentage of essential fat stores - represents an in vivo entity that remains relatively constant in its content of water, organic matter, & minerals throughout the adult’s life span - Essential fats - Fats necessary for normal physiologic functioning. - Includes lipids in the organs (nerves, heart, lung, kidneys, etc) - Females have a larger percentage of essential fat (higher LBM) due to sex-specific traits, deposits in breasts, hips, uterus, etc. Non-essential fats - Stored in adipose tissue - Adipose tissue contains 83% fat (triglycerides), 15% water, 2% protein. - Located below the skin and around organs - Variable depending on Gender, Age, Heredity, Metabolism, Diet, Activity level. Two-Component Model of Body Composition - Fat component - FFM component - Assumptions - Standard and constant density for fat and FFM across individuals - Densities do not change underwater - The individual differs from the reference body only via fat mass. (all individuals have the same amount of muscle and bone) - In reality, FFM density has been shown to vary with Age, Growth, sexual maturation, Gener, and ethnicity. Physical activity level and pathology also affects this number. Multicomponent Models of Body Composition - More accurate, eliminating many assumptions made in the 2-C model - Also takes body water and bone mineral density into account - Useful for developing population specific formulas Hydrostatic Weighing - Archimedes’s Princicple: - A body immersed in water is buoyed up with a force equal to the weight of the water displaced. - This means that weight loss underwater is directly proportional to the volume of water displaced by the body’s volume. - A valid and reliable way of getting body density (Db) Provides an estimate of body volume (BV) based on the displacement of water Db = BM / BV Db = Wa / [((Wa – Ww) / Dw) – (RV + GV)] Where; Wa = body weight (mass) in air (out of water) Ww = net body weight (mass) in water = net UWW Dw = density of water at a given temperature RV = residual volume in the lungs GV = volume of air in the gastrointestinal tract Weight of water displaced = Wa – Ww Volume of water displaced with air underwater = (Wa – Ww) / Dw Volume of water displaced without air underwater = [((Wa – Ww) / Dw) – (RV + GV)] GV is assumed to be 100 mL - Values needed for hydrostatic measurement: - Mass on land - Mass underwater - Water density - Residual lung volume - GV (assumed to be 100mL unless measured) - Water density changes slightly with temperature, negative correlation. The test is done with a water temperature of 34°-36°C - The test is usually done at RV, where the participant performs a maximal expiration as the test is done. This is the lung volume that is least affected by hydrostatic pressure. RV is usually 1.0-2.4 L in adults. - Different formulas are used for males and females, using age in years and height in cm. Sources of error: - Pretest guidelines: - Do not eat gas producing foods (12h) or do strenuous exercise (4h) prior to the exam. - Calibrate all equipment. - Use appropriate equipment - Do not move during exam - Wear swimsuit - Modification of HW procedures - UWW Client at Functional Residual Capacity (FRC) - Used when a client cannot expire maximally. - Db is measured at FRC; the volume of air in the lungs at the end of a normal expiration. - UWW Client at Total Lung Capacity (TLC) - Db is measured at TLC; the volume of air in the lungs at a maximal inspiration. - UWW Client at TLC With the Head Above Water Level - Same as above but with head above water, used for clients who are fearful of being submerged. - Gender specific equations exist to estimate Db at RV using the value obtained here. Disadvantages of underwater weighing - Time consuming and expensive - Requires adequate facilities and equipment - Highly dependent on client’s skill, cooperation and motivation - Requires additional equipment to measure RV Air displacement plethysmography - Used to measure Db and BV - Uses a specific machine (The Bod Pod) to measure air displacement - Based on Boyle’s law - Pressure and volume of a gas are inversely correlated. - Sources of error - Do not eat gas producing foods (12h) or do strenuous exercise (4h) prior to the exam. - Calibrate all equipment. - Use appropriate equipment - Do not move during exam - Wear swimsuit - Void bladder and bowels - Advantages - Quicker to administer - Requires minimal client compliance Requires minimal technician skill The Bod Pod is mobile, unlike a pool Can accommodate special populations Disadvantages - Equipment is expensive. And therefore only accessible to research facilities - Requires special clothing Dual-Energy X-ray Absorptiometry (DEXA) - Increasingly used as a reference method for body composition research - Gives estimates if BMD, fat mass and FFM at the body and regional levels - Works due to the differential penetration of X-rays through fat, muscle, or bone. - Advantages - Safe, low energy X-rays are used - Fast, 3-20m assessment - Requires minimal client cooperation & technician skill (automated) - Accounts for individual variability in BMD. - Less expensive and safer option than gold standard methods - Disadvantages - Expensive, and therefore only available in clinical or research settings. - Sources of error - Fasting prior to a scan increases accuracy - Variability amongst DEXA technologies is a major source of error Chapter 8: Assessing Body Composition; Part 2 Field methods for assessing body composition include bioelectrical impedance analysis method, ultrasound, skinfold, and anthropometric methods Bioelectrical impedance Analysis method (BIA) - One of the most popular methods for estimating relative body fat - A small current is generated and passed through the person being measured, the electrical impedance (resistance) is measured given the differential permeability of fat and other tissues to electricity. - BIA estimates FFM and total body water (TBW) Population specific formulas exist and are used to assess the results of BIA (impedance, resistance, reactance) - Pre-test guidelines - No eating/drinking 4h prior to exam - No moderate or vigorous exercise within 12h of the test - Void completely 30m before test - No diuretics (alcohol, coffee) within 48h of the test, unless prescribed - Postpone test for menstruated ladies - Advantages of BIA - Rapid, inexpensive - Non-invasive - More comfortable, does not intrude upon a client’s privacy - Little technician skill involved - Sources of error - Instrumentation - Results differ between brands - Client factors - Dehydrated - Menstruated clients - Environmental factors - Resistance is affected by skin temperature (inverse correlation) - Suboptimal body position - Lying supine is best - Using inappropriate population specific formulas for the client Ultrasound method - Allows one to assess adipose tissue thickness deep within the body - Two types of images: - Amplitude mode - Conversion of site specific fat thickness into %BF - A standardized A-Mode technique has not been developed yet - - Brightness modulation - A 2-dimensional image is produced to assess tissue depths - Interpreting results is difficult and requires expertise, however, a standardized technique has been developed for performing the exam. Sources of error - Technician skill - Technician should apply only enough pressure for an image to be produced, any more and they’d be compressing the tissue - Signal frequency, sound speed, mode of ultrasound (Machine specific factors) Skinfold Method (SKF) - A skinfold indirectly measures the thickness of subcutaneous adipose tissue. - There exists a standardized technique for SKF from the ASRM - Generalized equations are used for assessing results, although population specific formulas exist as well. - Assumptions - A skinfold accurately measures subcutaneous fat - The distribution of subcutaneous fat is similar for all members of a given gender - A relationship exists between subcutaneous fat and total body fat, and that a relationship exists between the sum of skinfold measurements and Db - Using multiple skinfold sites, a skilled technician can estimate the %BF within 3.5% of a reference HW value. - Sources of error - Technician skill - InterTechnician error is a major source of error in SKF - Intratechnician error is also an issue, technicians are advised to take two measurements in a rotation and to retake any measurement that differs by more than 10% at a given site. - Type of caliper - Technicians are advised to use the same caliper used to develop the population specific formulas they are using, and to calibrate equipment often. - Client factors - Dehydration Other Anthropometric methods - Anthropometry refers to the measurement of size and proportion of the body - Db, %BF, and FFM can be estimated via anthropometric prediction equations. - Some anthropometric methods include weight & stature, BMI, circumference, segment lengths, etc. - Circumference - Measure of the girth of a body segment - Skeletal diameter - Lean body mass can be estimated from skeletal diameter - This value is used to classify frame size in order to improve the validity of height-weight tables for evaluating body weight. - BMI - Assumes that a disproportionately heavy person is so because of an excessive amount of fat mass. Limitations: - Overestimates fat in muscular individuals - Underestimate fat in those who have recently lost muscle mass - Gives a high BMI for short people - Not a good measure of visceral fat - Does not provide information on fat distribution or body composition - Waist circumference - Useful measure of abdominal adipose tissue - A good predictor of predictor of obesity-related cardiometabolic disease - Can be couple with BI to provide a better assessment of health risk than either one alone - Waist-Hip ratio - indirect measure of lower- and upper-body fat distribution. - Limitations: - Post-Menopause women demonstrate male-like patterns of fat distribution - Not valid for prepubescent children - May not accurately reflect visceral fat changes - Waist-Height ratio - has been found to be consistently superior to both BMI & WC in terms of serving as an indicator of disease outcome or risk factors - WC should be less than half the height - Reference charts exist to classify people into different shape categories, can be used to assess health risk - Sagittal abdominal diameter - A measure of how much space there is between the umbilicus and the posterior aspect - simple indicator of the amount of dysfunctional visceral adipose tissue in the body - more strongly related to risk factors for cardiovascular & metabolic diseases than WC, WHR, & BMI Chapter 9:Designing Weight Management & Body Composition Programs; Part 1 Risks of being underweight: - Fluid-electrolyte imbalances - Osteoporosis/Osteopenia and bone fractures - Muscle wasting - Cardiac arrhythmias - Sudden death - Peripheral edema - Renal disorders - Reproductive disorders Risks of obesity - Cardiovascular disease - Stroke - Dyslipidemia - Hypertension - Osteoarthritis - Diabetes mellitus - Gallbladder disease - Various cancers 2 major types of obesity - Android Obesity: - upper-body obesity - apple-shaped - more typical of males but can occur in some women - More dangerous due to pressure on visceral organs - Gynoid obesity - lower-body obesity - pear-shaped - more typical of females but can occur in some men Subtypes of obesity - Metabolically Healthy, but Obese (MHO) Metabolically Obese, but Normal Weight (MONW) Metabolically Unhealthy & Obese (MUHO) Causes of Overweight & Obesity - Physiological Factors - Metabolism & Energy Balance - Hormones - Developmental Factors Genetic Factors Lifestyle Factors (most dramatic change in the past 50 years) Psychosocial Factors Energy Need & Energy Expenditure - Energy expenditure is measured in kcal, defined as the amount of heat needed to raise the temperature of 1 kg (2.2 lb) of water 1o C - Direct Calorimetry is used to measure the energy yield & caloric equivalent of various foods. (bomb calorimetry) - Indirect calorimetry - energy expenditure is measured during basal, resting, or activity states - Energy expenditure is estimated from O2 utilization. - 1 L O2 = 5 kcal expended - Energy expenditure is a function of basal metabolic rate and physical activity levels - Basal metabolic rate (BMR) - The minimum amount of energy (kcal) an individual needs in order to maintain essential physiological functions. - varies according to age, gender, body size, & body composition - Measured in a rested and fasted state (12h) and in a controlled environment. - Resting metabolic rate (REE) - Much easier to ascertain than BMR, it is the largest component of metabolism - Usually measured via indirect calorimetry - The minimum energy required to maintain essential physiological functions in a relaxed, awake, and reclined state. - Usually 10% higher than BMR - Measured 3-4h after a light meal (no physical exercise) Factors Affecting RMR - Heredity & environment - Hormones - Underproduction of thyroxine can reduce RMR 30 to 50%. - GH, epinephrine, & norepinephrine, & various sex hormones released during exercise may elevate RMR as much as 20%. - Age - RMR decreases 2 to 5 % during each decade of life after 25 years of age. - Gender (sex) - Men have higher RMRs than women on average due to more muscle mass and less fat% - Body composition - - For the same body weight, a muscular individual has a greater RMR than a fatter individual Body Size - Dieting decreases RMR, overeating regularly increases RMR Exercise - Physically fit individuals (athletes) have higher resting metabolic rates. Chapter 9:Designing Weight Management & Body Composition Programs; Part 2 2 Methods for Assessing Energy Expenditure - Factorial method - Total energy expenditure (TEE) method Weight Management Principles for Weight Loss - Well balanced diet fromm all relevant food groups - At least 3 meals per day - Quick weight loss diets, diet pills & appetite suppressants should be avoided - Carnitine does not promote fat loss - Behavioral components (Compulsive eating, binge eating) should be identified and stopped. - Gradual weight loss - No more than 2 lb weight loss per week - Weight loss should be due to the loss of fat, not lean tissue - A taller, heavier person will lose weight faster with the same diet as a smaller individual due to a higher RMR. - One must remember that the rate of weight loss decreases over time due to decreased difference between caloric intake and caloric needs. - Adequate caloric intake - Should be at least 1200 kcal/day - Adequate caloric deficit - Should not exceed 1000 kcal/day - 3500 kcal is needed to lose 1lb of fat Exercise Prescription for Weight Loss & Weight Management - An exercise prescription will differ based on a client’s goals (weight loss, weight maintenance) Chapter 10: Assessing Flexibility Flexibility is the ability of a joint, or series of joints, to move through a full ROM without injury Adequate levels of flexibility are needed to maintain functional independence and ADLs. It is important to include flexibility in fitness tests as a lack of flexibility is associated with musculoskeletal injuries & low back pain. Few studies substantiate its importance to health-related fitness. Limited evidence that a greater than normal amount of flexibility decreases injury risk. Research suggests individuals with ankylosis or hypermobility are at higher risk than others for musculoskeletal injuries. Flexibility and joint stability are dependent on - Joint structure - Strength and number of muscles spanning the area. - strength & number of ligaments spanning the joint. - Relative contribution of soft tissue structures to the total resistance encountered by the joint during movement (Johns & Wright, 1962). - Joint capsule: 47% - composed predominantly of a nonelastic connective tissue called collagen. - Muscle & fascia: 41% - composed of an elastic connective tissue called elastin. - most important structures in terms of reducing resistance to movement & increasing dynamic flexibility. - Tendons & Ligaments: 10% - Skin: 2% Static flexibility - is a measure of the total ROM at the joint. - is limited by the extensibility of the musculotendinous unit. Dynamic flexibility - is a measure of the rate of torque or resistance developed during stretching throughout the ROM. Joint classification by Structure & Function Muscle-Tendon Unit - affects both static flexibility & dynamic flexibility. - is attributed to the: - viscoelastic properties of connective tissues, - degree of muscular contraction from the stretch reflex. Factors Affecting Flexibility - Body type - Obese people (high subcutaneous fat) and bodybuilders (hypertrophied muscles) may have poor flexibility. - Age - Increased muscle stiffness and lower stretch tolerance with age. A decline in physical activity and arthritis are primary causes of age-related flexibility loss. - Gender - Females tend to be more flexible than males at all ages, this is attributed to: - gender differences in pelvic structure - hormones that may affect connective tissue laxity. - Physical activity - Habitual movement patterns & lack of physical activity are apparently more important determinants of flexibility than age, gender, & body type. - Habitual movement patterns may restrict ROM due to tightening of muscle tissue - Ex: Repetitive patterns such as jogging or maintaining a posture such as sitting down for long periods of time. - A lack of physical activity is a major cause for inflexibility. Muscles tend to tighten when not used. Methods of Measuring Static Flexibility - Goniometer - is a protractor-like device with 2 steel or plastic arms that measures the ROM as the difference between the joint angles in units of degrees at the extremes of a movement. - Digital goniometers exist as well. - Electrogoniometer - is composed of 1 or 2 flexible potentiometers, or strain gauges, between 2 end-blocks. - Easier to use because the technician’s hands are free. - Measurements can be made in 2 planes simultaneously when using a 2-channel electrogoniometer. - Leighton Flexometer - is a device composed of a weighted 360 degree dial & weighted pointer that measures the ROM for a given joint in relation to the downward pull of gravity on the dial & pointer. - Inclinometer - is another type of gravity-dependent goniometer that measures the angle between the long axis of the moving segment & the line of gravity. - Used mostly for the back. - is easier to use than the flexometer & universal goniometer because it is held by hand on the distal end of the moving body segment during the measurement and it doesn’t have to be aligned with specific bony landmarks. The goniometer, electrogoniometer, leighton flexometer, and inclinometer are direct measures of flexibility. - The validity & reliability of devices such as goniometers & inclinometers that measure ROM directly are highly dependent on the joint being measured and technician skill. - The intratester & intertester reliability of goniometric measurements are affected by difficulty in identifying the axis of rotation and Palpating bony landmarks. Intertester reliability of inclinometer measurements is variable & joint specific. - The measurement of upper body flexibility tends to be more reliable than lower body measurements. - Radiography is considered to be the best reference method for establishing the validity of goniometric measurements. Methods of Measuring Static Flexibility (Cont’d) - Sit-and-Reach Test - Most used flexibility test worldwide, given the belief that lack of flexibility is associated with low back pain & musculoskeletal injuries. Chapter 11: Designing Programs for Flexibility and Low Back Care Flexibility Training - a systematic program of stretching exercises designed to progressively increase the ROM of joints over time - Stretching improves flexibility & ROM Common Terms Used in Flexibility Literature - Elasticity - the property that enables a tissue to return to its original shape or size when a force is removed. - Plasticity - the property of a material to permanently deform when it is loaded beyond its elastic range - Stress - defined as the force per unit area of a material (= force / cross sectional area). - Strain - the change in length or amount of deformation caused by the applied force. Is defined as extension per unit length (= extension / original length). - Stiffness - the ratio of stress to strain, or force to deformation. - the ratio of the change in force to the change in length. - Viscosity - the property of materials to resist loads that produce shear & flow - an apparent force that prevents fluids from flowing easily. - Viscoelasticity - also known as anelasticity, is the study of materials that exhibit both viscous & elastic characteristics when undergoing deformation. - defined as a combination of viscous & elastic properties exhibited by biological tissues. Viscoelastic Properties of the Muscle-Tendon Unit - Viscoelastic Stress Relaxation - Viscoelastic Creep Neurophysiology of Flexibility - Spinal reflexes - Stretch reflex by muscle spindles - Inverse stretch reflex by golgi tendon organs (GTOs) - - Autogenic Inhibition - Relaxation occurring in the same muscle experiencing increased tension. - Accomplished by actively contracting a muscle immediately before a passive stretch of the same muscle. - Ex: Somebody drops a very heavy object in your hand, your bicep reflexively relaxes and drops the object. Reciprocal inhibition - Relaxation that occurs in the muscle opposing the muscle experiencing the increased tension. - Accomplished by simultaneously contracting the muscle opposing the muscle being passively stretched. - - Ex: Your hamstrings reflexively relaxes during a strong kick in order to provide the least resistance to your quads trying to extend the knee. Gate Control Theory of Pain Modulation - A theory that postulates that when pressure receptors (Type III afferent) activated during isometric contractions could inhibit pain receptors (type IV afferent). - Explains the subsequent ability to tolerate stretching found in PNF stretching. Training Principles - Overload - Stretch the muscles beyond their normal resting length but not beyond the pain-free ROM. - Specificity - Select exercises that stretch the appropriate muscle groups to increase a particular joint’s ROM. - Progression - Periodic increase in total time of stretching: increase duration &/or number of repetitions of each stretch - Interindividual variability - The pain-free ROM varies among individuals: depends on their stretch tolerance & perception of stretch & pain.