Module 5 Resistance

Types of contractions

*Isometric contraction (Static Exercise) -Is a static contraction that produces a constant force without an appreciable change in length of the muscle and without visible joint motion. The need for static strength and endurance is important for almost all aspects of control of the body during functional activities. *Rationale and Indications for use of Isometric Exercise: -Minimizes muscle atrophy when joint movement is not possible (casts, splints, skeletal traction) -To facilitate muscle activity in order to begin to re-establish neuromuscular control but protect healing tissues when joint movement is not advisable after soft tissue injury or surgery. -To develop postural or joint stability -To improve muscle strength when use of dynamic resistance exercise could compromise joint integrity or cause joint pain -To develop static muscle strength at particular points in the ROM consistent with specific task-related needs -Can be used when initiating stabilization exercises *Disadvantages -The strength gains are developed at a specific point in the range or motion and not through-out the range (unless performed at multiple angles) -Not all of a muscle's fibers are activated-there is predominantly an activation of slow twitch (type I) fibers -There are no flexibility or cardiovascular fitness benefits -Peak effort can be injurious to the tissues due to vasoconstriction and joint compression forces -There is limited functional carryover -Considerable internal pressure can be generated, especially if the breath is held during contraction. *Dynamic Exercise: Constant External Resistance (DCER) (aka isotonic contraction) -Dynamic exercise against constant external resistance is a form of resistance training in which a limb moves through a ROM against a constant external load. This includes concentric and eccentric muscle contractions. -Concentric contraction is the shortening of the muscle. It is a form of dynamic muscle loading in which tension in a muscle develops and physical shortening of the muscle occurs as an external force (resistance) is overcome, as when weight lifting. -Eccentric contraction is the elongation of the muscle. (Think "e" for eccentric and elongation.) This involves dynamic loading of a muscle beyond its force-producing capacity, causing physical lengthening of the muscle as it attempts to control the load, as when lowering a weight. -Research has shown that the greatest strength gains are made when the muscle is exercised eccentrically. -When applying resistance manually, resistance is applied to the distal end of the segment being strengthened. Resistance is applied in the direction opposite of that of the limb movement to resist a concentric muscle contraction and in the same direction as limb movement to resist an eccentric contraction. *Concentric vs. Eccentric -Concentric contractions are commonly used in the rehabilitation process due to the frequent occurrence in ADL's example: the biceps curl and the lifting of a cup to the mouth -Greater loads can be controlled with eccentric rather than concentric exercise -Training-induced gains in muscle strength and mass are greater with maximum-effort eccentric training than maximum-effort concentric training -Adaptations associated with eccentric training are more mode and velocity specific than adaptations as the result of concentric training -Eccentric muscle contractions are more efficient metabolically and generate less fatigue than concentric contractions -Following unaccustomed, high-intensity eccentric exercise, there is greater incidence and severity of delayed-onset muscle soreness than after concentric exercise *Rationale for use of Concentric and Eccentric Exercise -Concentric muscle contractions accelerate body segments -Eccentric muscle contractions decelerate body segments (e.g. during sudden changes of direction or momentum) Eccentric contractions also act as a source of shock absorption during high-impact activities. *A comparison of the three types of muscle actions in terms of maximal force production, according to Elftman's proposal, shows that: -Eccentric maximum tension > Isometric maximum tension > Concentric maximum tension *Delayed-Onset Muscle Soreness (DOMS) -DOMS is exercise induced muscle tenderness or stiffness that occurs 24 to 48 hours after vigorous exercise. -It is important to note that rapidly progressed, high intensity eccentric muscle contractions are associated with significantly higher incidence and severity of DOMS. -By progressing intensity and volume of exercise gradually, this can prevent or minimize the effects of DOMS. -Evidence suggests that by performing low-intensity warm-up and cool-down activities or gently stretching the exercised muscle before and after strenuous exercise, this can help to reduce the occurrence of DOMS. *Open and Closed Chain Exercise -The mode of an exercise can be altered if the position of a limb is in a weight bearing or non-weight bearing position. These concepts were created to demonstrate a difference in how muscle recruitment changes with different types of positions. -When a non-weight bearing position is assumed and the distal segment (foot and hand) moves freely during exercise, the term is open-chain. -Example: Standing while performing weighted knee flexion. Tibia moves over the femur. -When weight bearing position is assumed and the body moves over a fixed distal segment, the term is closed-chain. -Example: Performing a standing short arc squat, the femur moves over the tibia while weight bearing. *Rationale for use of Open-Chain and Closed Chain Exercises -The decision on whether to choose open-chain or closed-chain exercises depends on the goals of the rehab program and an analysis of benefits and limitations in either form of exercise. -It is believed that closed-chain exercises are "more functional" than open-chain exercises, but some studies still argue this. -The fact of the matter is with open-chain exercises you can target specifically one movement at a joint. -With closed-chain exercises you can target synergistic movement patterns that mimic the firing patterns of functional tasks. -Studies also suggest that closed-chain exercises cause significantly less shear forces on a joint than the open-chain exercises. -The use of a stable and then unstable base during closed chain exercises encourages co-contraction of the agonist and antagonist.

Strength Training

*Terminology -Strength training - is a systemic procedure of a muscle or muscle group lifting, lowering, or controlling heavy loads (resistance) for a relatively low number of repetitions or over a short period of time. -Power - is the combination of strength and speed of a movement. The main focus of power training is to maximize strength in the smallest amount of time. -Intensity - of exercise in a resistance training program is the amount of resistance (weight) imposed on the contracting muscle during each repetition of an exercise. -Volume - of exercise is the summation of the total number of repetitions and sets of a particular exercise during a single exercise session. There is an inverse relationship between the sets and repetitions of an exercise and the intensity of the resistance. The higher the intensity (load), the lower the number of repetitions and sets possible. Conversely, the lower the load, the greater the number of repetitions and sets possible. Therefore, the exercise load directly dictates how many repetitions and sets are possible. -Frequency - in a resistance program refers to the number of exercise sessions per day or per week. -Duration - of exercise is the total number of weeks or months during which a resistance program is carried out, this is typically determined by the PT. *Strength Training Zone -After a RM is ascertained, the exercise load (amount of resistance) to be used at the initiation of resistance training is calculated as a % of the 1-RM. -This % can range from as low as 30-40% for sedentary, or untrained individuals or very high (>80%) for those that are highly trained in order to achieve training-induced adaptations. -For the healthy but untrained adult, the strength training zone will usually fall between 40-70% of the RM. To begin a strength training program, the lower percentages of this range are safer in order to focus on learning correct exercise form and technique prior to increasing the exercise load. -Low exercise loads are recommended for children and the elderly. Pt.'s that experience significant deficits in muscle strength or for targeting muscular endurance, using lower loads at the 30-50% level is safe yet still challenging. *Guideline of repetitions (for the average, untrained adult) 90% of 1-RM 4-5 repetitions (other sources state that at 90% of 1-RM, only 3 repetitions are possible) 75% of 1-RM 10 repetitions 60% of 1-RM 15 repetitions *Sets - there is no optimal number of sets per exercise session, but 2-4 sets is a common recommendation for adults. *Exercise Order - The sequence that exercises are performed in an exercise program has an impact on muscle fatigue and adaptive training. -Large muscle groups should be exercised before small muscle groups -Multi-joint exercises should be performed before single-joint exercises -Higher intensity exercises should be performed before lower intensity exercises. *Rest Interval -Purpose - rest is a critical element of a resistance training program and is necessary to allow time for the body to recuperate from the acute effects of exercise associated with muscle fatigue. -Integration of rest into exercise - this is dependent upon the intensity and volume of exercise. In general, the higher the intensity the longer the rest interval, (>3 minutes is recommended). For moderate intensity, a rest period of 2-3 minutes is recommended. Low intensity exercises, a shorter rest period is recommended. -The rest period between sets can be determined by how long it takes the breathing rate or pulse of the pt. to return to the steady state. *Endurance Training -Endurance is defined as the ability to perform low-intensity, repetitive, or sustained activities over a prolonged period of time. -Endurance uses slow-twitch muscle fibers (Type I) to generate a small amount of force but can sustain the contraction for a long period of time. For many pt.'s with impaired muscle performance, endurance training has a more positive impact on improving function than strength training. *Repetitions and Sets -How do you know how many repetitions and sets to assign to a pt.? Trial and error based on trying to achieve a reasonable number. Many therapists use a combination of 10 reps with 1, 2, or 3 sets. Other therapists use a combination of 15 reps with 1, 2, or 3 sets. Many therapists assign similar numbers for all exercises to simplify the routine for the pt. This approach does not necessarily fatigue each muscle, but this approach is easier for pt.'s to remember the exercise program. *Compensation and Substitution -Pt.'s challenged beyond their ability often recruit unwanted muscle groups in order to complete the task. Pt.'s must do the exercises correctly in order to maximally benefit from the therapeutic exercise. *Strength vs. Endurance -Strength - is defined as the greatest measurable force that can be exerted by a muscle to overcome resistance during a single, maximum effort. Strength uses fast-twitch muscle fibres (Type II) to generate a large amount of force in a short period of time but fatigue quickly. Strength is improved with high resistance and low repetitions. -Endurance - is defined as the ability to perform low-intensity, repetitive, or sustained activities over a prolonged period of time. Endurance is improved with low resistance and high repetitions. *Caution must be taken with pt.'s diagnosed with osteoporosis whose bones are unable to withstand normal stresses and are highly susceptible to pathological fracture. -Other pt. populations that require close monitoring include: -Pt.'s with an acute illness/fever -Pt.'s with an acute injury -Postsurgical pt.'s -Pt.'s with cardiac/pulmonary disease (e.g. edema, weight gain, unstable angina) -Pt.'s who are obese -Pt.'s with diabetes *Contraindications to strength training (Dutton) -Unstable angina -Uncontrolled hypertension -Uncontrolled dysrhythmias -Hypertrophic cardiomyopathy -Certain stages of retinopahty *Plyometrics -The traditional definitions of plyometrics was associated with quick rapid movement involving a prestretch of the contracting muscle, which stores elastic energy in the muscle and activates the stretch reflex. The muscles ability to use the stored elastic energy is affected by time, the magnitude of the stretch, and the velocity of the stretch. -Movement patterns in both athletics and activities of daily living involve repeated stretch shortening cycles where a downward eccentric movement must be stopped and converted into an upward concentric movement in a desired direction. *Discontinue exercise if the pt. experiences pain, dizziness, or unusual shortness of breath. *Overtraining - is a term commonly used to describe a decline in physical performance in healthy individuals participating in high intensity, high-volume strength and endurance training. -Overtraining is brought on by inadequate rest intervals between exercise sessions, too rapid progression of exercises, and inadequate diet and fluid intake. *Overwork - refers to progressive deterioration of strength in muscles already weakened by nonprogressive neuromuscular disease. -Prevention is the key to dealing with overwork weakness. Pt.'s in resistance exercise programs who have impaired neuromuscular function or a systemic, metabolic, or inflammatory disease that increase susceptibility to muscle fatigue must be monitored closely, progressed slowly and cautiously, and re-evaluated frequently.

Resistance

*What is resistance? -Resistance is any form of active exercise in which a muscle contraction is resisted by an outside force. *How do you decide the appropriate level of resistance? -The therapist usually can use the MMT scale to make an educated guess on where the pt. should begin in their resistance. -If the pt. is unable to progress from a gravity eliminated position directly to against gravity then the pt. can be placed in a gravity minimized position. Not all muscle actions have a gravity minimized position. -The pt. needs to feel successful with the exercise you assign and be able to complete 100% of the ROM with the resistance you choose. -The level of resistance is dependent upon the individual's level and ability to participate. It is also based on the size of the muscle. Types of Resistance *Gravity - alone can supply sufficient resistance with a weakend muscle. With respect to gravity, muscle actions may occur in: -the same direction of gravity (downward), requiring an eccentric contraction -the opposite direction of gravity (upward), requiring a concentric or isometric contraction. -a direction perpendicular to gravity (horizontal), minimizng the effects of gravity and therefore appropriate for weaker muscles -The same or opposite direction as gravity but at an angle requiring multi-planar concentric/eccentric contractions *Body Weight - a wide variety of exercises have been developed that use no equipment and instead rely on the pt.'s body weight for the resistance (push-up) Mechanical Resistance Exercise - is a form of active-resistive exercise in which resistance is applied through the use of equipment or mechanical apparatus. *Small weights - cuff weights and dumbells are economical ways of applying a constant resistance. Small weights are typically used to strengthen the smaller muscles or to increase the endurance of larger muscles by increasing the number of reps. Free weights also provide more versatility than exercise machines, especially for three-dimensional exercises. *Surgical tubing/Theraband - Elastic resistance offers a unique type of resistance because the amount of variable resistance offered by elastic bands or tubing depends on the internal tension produced by the material. *Exercise machines - in situations where the larger muscle groups require strengthening, a multitude of specific indoor exercise machine can be used. These machines are often used in the more advanced stages of a rehabilitation program when more resistance can be tolerated, but they can also be used in the earlier stages depending on the size of the muscle undergoing rehabilitation. -Although these machines are a more expensive alternative to dumbell or elastic resistance, they do offer some advantages. -Provide more adequate resistance for large muscle groups than can be achieved with free weights/cuff weights or manual resistance -Typically safer than free weights, because they provide control throughout the range. -Provide the clinicain with the ability to quantify and measure the amount of resistance the pt. can tolerate over time. -The disadvantages of exercise machines include: -the inability to modify the exercise to be more functional or three-dimensional -the inability to modify the amount of resistance at particular points of the range. *Manual resistance -A type of active exercise in which another person provides resistance manually. An example is PNF. -The advantages of manual resistance when applied by a skilled clinician are: -Control of the extremity position and force applied. This is especially useful in the early stages of an exercise program when the muscle is weak. -More effective re-education of the muscle or extremity through the use of diagonal or functional patterns of movement. -Critical sensory input to the pt. through tactile stimulation and appropriate facilitation techniques (e.g. quick stretch) -Accurate accommodation and alterations in the resistance applied throughout the range; for example an exercise can be modified to avoid a painful arc in the range. -Ability to limit the range. This is particularly important when the amount of range of motion needs to be carefully controlled (postsurgical restrictions or pain) -The disadvantages of manual resistance include: -the amount of resistance applied cannot be measured quantitatively -the amount of resistance is limited by the strength of the clinician/caregiver or family member - No consistency of the applied force throughout the range, and with each repetition. *No matter what exercise we are instructing with, we need to always consider correct positioning and posture. It doesn't matter how many reps of an exercise a pt. can do if they aren't doing it correctly. -It is good practice to have your pt. demonstrate the exercises they have been instructed with and ensure they are doing them correctly before continuing with any additional exercises. -We always need to ask about pain and educate our pt.'s about the difference between pain and discomfort with muscle fatigue when initiating resistance training. -Sometimes posture, body mechanics, and core stability are the first areas addressed in the pt.'s Ther Ex.

Exercise Principals

There are several principals that must be taken into consideration when developing an exercise program for a pt. *Overload Principle -(Dutton) - The principle of overload stated that a greater than normal stress or load on the body is required for training adaptation to take place. To increase strength, the muscle must be challenged at a greater level than it is accustomed to. High levels of tension will produce adaptations in the form of hypertrophy (an increase in the size (bulk) of an individual muscle fiber caused by an increase in myofibrillar volume) and recruitment of more muscle fibers. -In a strength training program, the amount of resistance applied to the muscle is incrementally and progressively increased -For endurance training, more emphasis is placed on increasing the time a muscle contraction is sustained or the number of repetitions performed than on increasing resistance. Precaution- The muscle and related body systems must be given time to adapt to the demands of an increased load or repetitions before the load or number of repetitions is again increased. *SAID Principle -Which stands for Specific Adaptation of Imposed Demands, states that tissues remodel in accordance to the stresses placed upon them. This principle is based on Wolff's Law, which states that body systems adapt over time to the stresses placed upon them. -In short, to develop endurance for a marathon, one must train by running long distances. -Another example, if someone lifts light weights for high repetitions, their body will adapt specifically towards muscular endurance. If someone lifts heavy weights with low repetitions, their body will adapt specifically towards producing maximal strength. You get what you train for. *Specificity of Training -This concept states that adaptive effects of training such as improved strength and endurance are highly task-specific. Therefore, exercises in a training program should mimic the anticipated function. In some instances, there is a varying degree of cross-over whereby adaptation will enhance traits needed to perform another activity. -For example: grip strength is an additional component that is required in order to perform pull-ups or deadlifts, so you may train in grip strength. This is why many athletes incorporate cross-training into their programs. -A runner may also use a weighted vest in the deep end of a pool and mimic running in order to reduce the stresses placed on a joint rather than training with direct contact with the ground. *Reversibility Principle -If you don't use it you lose it. Adaptive effects of training such as improved strength and endurance are transient unless maintained by functional activities or a regular exercise program. *Reversibility principle (Dutton) - any adaptive changes in the body systems, such as increased strength or endurance, in response to a resistance exercise program are temporary unless training-induced improvements are regularly used through functional activities or resistance exercises. These changes can begin within a week or two after the cessation of resistance exercises and will continue until the training effects are lost. -While rest periods are necessary for recovery, extended rest intervals reduce physical fitness. *Fatigue -Defined as a diminished response of a muscle to a repeated stimulus. Remember, the muscle needs to be exercised to fatigue in order to improve and gain strength. -The signs of fatigue are looked for at the end of the repetitions that have been prescribed, not at the beginning. -Factors that influence fatigue are diverse: a pt.'s health status, diet, or lifestyle (sedentary or active) all influence fatigue. -It is advisable for a therapist to become familiar with the patterns of fatigue associated with different diseases and medications. -Environmental factors such as outside or room temperature, air quality, and altitude also influence how quickly the onset of fatigue occurs and how much time is required for recovery from exercise. *Signs and symptoms of muscle fatigue -An uncomfortable sensation within the muscle, even pain and cramping. -Tremulousness in the contracting muscle. -Active movements are jerky, not smooth. -Inability to complete the movement pattern through the full range of available motion during dynamic exercise against the same level of resistance. -Use of substitute motions, that is, incorrect movement patterns, to complete the movement pattern. -Inability to continue low-intensity physical activity. -Decline in peak torque during isokinetic testing. *Muscle Fiber Type and Resisatnce to Fatigue -The fiber-type distribution of a muscle affects how resistant it is to fatigue -Type I (tonic, slow-twitch) muscle fibers generate a low level of muscle tension but can sustain the contraction for a long period of time. These fibers are geared towards aerobic metabolism and are very slow to fatigue. -Type II (phasic, fast-twitch) muscle fibers generate a great amount of tension in a short period of time. These fibers are geared towards anaerobic metabolic activity and tend to fatigue quickly. *Energy Systems -Aerobic Exercise - Associated with low-intensity, repetitive exercise of large muscle groups performed over an extended period of time. This mode of exercise primarily increases muscular and cardiopulmonary endurance. -Anaerobic Exercise - Involves high-intensity (near maximal) exercise carried out for a very few number of repetitions because muscles rapidly fatigue. Strengthening exercises fall in this category. *Progressive Resistance Exercise (PRE) -The therapist may need to adjust the exercise frequently to maintain fatigue as the muscle strength improves. Progression of an exercise by modifying parameters is termed PRE. The therapist may change the following parameters: -Patient position -Type of resistance (e.g. isometric, theraband, hand/ankle weights) -Lever arm (short or long) -Repetitions -Sets -Contraction duration (for isometrics) -Frequency per day or week *Most therapists change only one to two parameters at a time. Too many changes tend to be confusing for pt.'s. The therapist should achieve fatigue with a reasonable number of changes.

Equipment for Resistance Training

*Free Weights *Simple Weight-Pulley System *Variable Resistance Units (Weight-Cable or Hydraulic and Pneumatic) *Elastic Resistance Devices *Dynamic Stabilization Training -Body Blade -Swiss Balls (Stability Balls) *Equipment for Closed-Chain Training -Body Weight Resistance: Multipurpose Exercise Systems -Slide Boards -Mini Trampolines *Reciprocal Exercise Equipment -Stationary Exercise Cycles -Stair-Stepping Machine -Elliptical Trainers -Upper Extremity Ergometers

Progressive Resistance Exercise (PRE)

Applying resistance during exercise in anatomical planes, diagonal patterns, and combined task-specific movement patterns should be integral components of a carefully progressed resistance exercise program. *PRE is a system of dynamic resistance training in which constant external load is applied to the contracting muscle by some mechanical means and incrementally increased. -The Repetition Maximum (RM) is used as the basis for determining and progressing the resistance. -Repetition Maximum (RM) is the greatest amount of weight a muscle can move through the full range of motion a specific number of times in a load-resisting exercise routine. *Use of a repetition maximum -Documents a baseline measurement of dynamic strength to which improvements can be compared -Identifies initial exercise load to be used for a specified number of repetitions *Precautions of repetition maximum -Use of a 1-RM as a baseline measurement of dynamic strength is inappropriate for some pt. populations because it requires one maximum effort. It is not safe for pt.'s, for example: -With joint impairments -Pt.'s who are recovering from or who are at risk for soft tissue injury -Pt.'s with known or at risk for osteoporosis or cardiovascular pathology *Delorme and Oxford Regimens -In order to use the Delorme and Oxford techniques you must determine a pt.'s 1 rep max (1-RM), which is the ability to lift the greatest amount of weight 1 time. Once this is determined, 75% of the 1-RM will now allow for most pt.'s to lift that weight 10x. -To figure for Delrome and Oxford scales, you must take percentages of the 10-RM to determine the protocol to follow. (announcement week 4 has an example) -The Delorme technique builds a warm-up period into the protocol, whereas the Oxford technique diminishes the resistance as the muscle fatigues. Both regimens incorporate a rest interval between sets; both increase the resistance incrementally over time to apply progressive overload; and both have been shown to result in training-induced strength gains. -Typical PRE programs produce training-induced strength gains using 2-3 sets of a 6-12 repetitions. *Daily Adjustable Progressive Resistive Exercise (DAPRE) (pg.220 Kisner) -The DAPRE approach: it uses a 6 rep max and starts with 10 reps for set 1 at 50% of the 6 rep max. Set 2 at 6 reps at 75% of the 6 rep max. Set 3 100% of the 6 rep max for as many reps as possible and on the 4th set depending on how difficult the 3rd set was, a PTA may choose to decrease, keep the same or increase the weight by 5-15 lbs. -The adjusted working weight, which is based on the maximum number of repetitions possible using the working weight in set #3 of the regimen, determines the working weight for the next exercise session.

Specific Techniques with PNF

Stretch reflex - The stretch reflex is facilitated by a rapid stretch (overpressure) just past the point of tension to an already elongated agonist muscle. The stretch reflex is usually directed to a distal muscle group to elicit a phasic muscle contraction to initiate a given diagonal movement pattern. The quick stretch is followed by sustained resistance to the agonist muscles to keep the contracting muscles under tension. -Precaution: Use of stretch reflex, even prior to resisted isometric muscle contractions, is not advisable during the early stages of soft tissue healing. It is also inappropriate with acute or active arthritic conditions. Rhythmic Initiation - is used to promote the ability to initiate a movement pattern. The therapist moves the pt.'s limb passively through the available range of desired movement pattern several times so the pt. becomes familiar with the sequence of movements within the pattern. Rhythmic initiation also helps the pt. understand the rate at which movement is to occur. Slow reversal - involves dynamic concentric contraction of a stronger agonist pattern immediately followed by dynamic concentric contraction of the weaker antagonist pattern. There is no voluntary relaxation between patterns. This promotes rapid, reciprocal action of agonists and antagonists. Alternating Isometrics - another technique to improve isometric strength and stability of the postural muscles of the trunk or proximal stabilizing muscles of the shoulder girdle and hip is alternating isometrics. Manual resistance is applied in a single plane on one side of the body segment and then on the other. The pt. is instructed to "hold" his or her position as resistance is alternated from one direction to the opposite direction. Rhythmic Stabilization - is used as a progression of alternating isometrics and is designed to promote stability through co-contraction of the proximal stabilizing musculature of the trunk as well as the shoulder and pelvic girdle regions of the body. Rhythmic stabilization typically is performed in weight-bearing positions to incorporate joint approximation into the procedure, hence further facilitating co-contraction. The therapist applies multidirectional, resistance by placing manual contacts on opposite sides of the body and applying resistance simultaneously in opposite directions as the pt. holds the selected position.