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Regaining Muscular Strength, Endurance and Power Regaining Strength, Endurance & Power Critical to maintain and improve in each area in order to achieve competitive fitness levels and return athlete to functional level following injury Muscular Strength Ability to generate force against some resistance Important to maintain normal levels for normal healthy living Imbalance or weakness can impair normal function Muscular Endurance Ability to perform repetitive muscular contractions against some resistance Power Ability to generate force quickly Combination of strength & speed Performance is limited without power Types of Skeletal Muscle Contraction • Isometric Contraction – Contraction that produces m. tension but no change in m. length • Concentric Contraction – Contraction that causes m. shortening while tension increases to overcome some resistance • Eccentric Contraction – Resistance is greater than the muscular force being produced & muscle lengthens while producing tension • Econcentric contraction – Controlled concentric & eccentric contraction of same muscle over 2 separate joints – Hamstring and rectus femoris of quadriceps • Strength training must focus on functioning of muscle – Multi-planar – Various contractions - functionally Factors That Determine Levels of Strength, Endurance & Power • Size of Muscle – Proportional to cross-sectional diameter of muscle fibers – Increased cross-sectional area = increased strength and force production • Number of Muscle Fibers – Strength is a function of the number and diameter of muscle fibers – Number of fibers is inherited characteristic • Neuromuscular Efficiency – Strength is directly related to efficiency of the neuromuscular system – Initial increases in strength during first 8-10 weeks are attributed to neuromuscular efficiency – Efficiency enhanced strength in 3 ways • Increase # of motor unit recruitment • Increase in firing rate of each motor unit • Enhance synchronization of motor unit firing • Biomechanical Considerations – Position of tendon attachment • Relative position of tendon attachment to fulcrum of the joint – The closer the tendon is to resistance, the greater the force produced • Change in attachment will alter force generating capabilities • The position of attachment of the muscle tendon on the lever arm can affect the ability of that muscle to generate force. • B should be able to generate greater force than A because the tendon attachment on the lever arm is closer to resistance. • Biomechanical Considerations – Length-Tension Relationship • Length of muscle determines tension that can be created • Varying lengths will produce varying tensions • Determined by overlap of actin-myosin filaments • Age – Men & women increase strength throughout puberty & adolescence – Peaks at age 20-25 – After age 25, max strength declines 1% annually – Decline is related to physical activity – Able to retard decline in performance through activity • Overtraining – Imbalance between exercise and recovery • Training exceeds physiological and psychological capacity of individual – Can have negative effect on strength training – May result in psychological or physiological breakdown • Injury, illness, and fatigue can be indicators Fast-Twitch vs. Slow Twitch • Slow Twitch Fibers – – – – Type I or slow oxidative (SO) More resistant to fatigue Time required to generate force is greater in slow twitch fibers Primarily associated with long duration, AEROBIC activities • Fast Twitch Fibers – Type IIa (fast oxidative glycolytic- FOG) • Moderately resistant to fatigue – Type IIb (fast glycolytic - FG) • Fatigues rapidly – true fast twitch – Type IIx – fatigue resistant with force capacity (a<x<b) – Produce quick, forceful contractions – Short-term, high intensity activities, ANAEROBIC activities • Ratio in Muscle – – – – Both fiber types exist in individual muscles Ratio varies by muscle and by individual Postural muscles = ↑ % primarily type I fibers Power, explosive strength muscles = ↑ % type II fibers – Genetically determined • Large role in determining ability for a given sport activity – Fiber changes due to training • Enhanced metabolic capabilities through specific training Physiology of Strength Development • Muscle Hypertrophy – 3 theories – Hyperplasia – ↑ in number of muscle fibers • Genetically determined & does not seem to increase with training • Evidence exists of fibers splitting – conducted in animals – Hypothesized increased number of capillaries – partially correct • No new capillaries • Increase in dormant capillary activity to meet needs of muscle – **Increased size and number of myofilaments • Actin (thin) and Myosin (thick) • When muscle is stimulated to contract, cross-bridges pull myofilaments closer which shortens the muscle, & produces movement at joint that muscle crosses – Reversibility – adaptations of muscle due to training can begin to reverse within 48 hours of removing training Other Physiological Adaptations to Resistance Exercise • Strength of non-contractile structures – Tendons and ligament increase – Increased bone-mineral content • Improved oxygen uptake – If resistance training is high enough to elicit a cardiovascular response/adaptation • Increased metabolic enzymes Elements of a Resistance Exercise Program • Alignment of segments of the body during exercise • Stabilization of proximal or distal joints to prevent substitution • Intensity: the exercise load (level of resistance) • Volume: number of repetitions and sets; number of exercises per session • Frequency: the number of exercise sessions per day or per week • Rest interval: time allotted for recuperation between sets and sessions of exercise • Duration: total time frame of a resistance training program Elements of a Resistance Exercise Program • Mode of exercise: type of muscle contraction, position of the patient, application of resistance, arc of movement, or the primary energy system utilized • Speed of exercise • Periodization: variation of intensity and volume during specific periods of resistance training • Integration of function: use of resistance exercises that replicate functional demands Substitute motions Compensatory movement patterns caused by muscle action of a stronger adjacent agonist or of a muscle group that normally serves as a stabilizer (fixator). Alignment Proper alignment is determined by the direction of muscle fibers and the line of pull of the muscle to be strengthened. For example, to strengthen the gluteus medius, the hip must remain slightly extended, not flexed, and the pelvis must be rotated slightly forward as the patient abducts the lower extremity against the applied resistance. If the hip is flexed as the leg abducts, the adjacent tensor fasciae latae becomes the prime mover and is strengthened. Stabilization Stabilization refers to holding down a body segment or holding the body steady. To maintain appropriate alignment, ensure correct muscle action and movement pattern, and avoid unwanted substitute motions during resistance exercise, effective stabilization is imperative. External stabilization can be applied manually by a therapist or sometimes by the patient, with equipment, such as belts and straps, or by a firm support surface, such as the back of a chair or the surface of the treatment table. Internal stabilization is achieved by an isometric contraction of an adjacent muscle group that does not enter into the movement pattern but holds the body segment of the proximal attachment of the muscle being strengthened firmly in place. For example, when performing a bilateral straight leg raise, the abdominals contract to stabilize the pelvis and lumbar spine as the hip flexors raise the legs. Intensity The 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. The amount of resistance is also referred to as the exercise load (training load), that is, the extent to which the muscle is loaded. or how much weight is lifted, lowered, or held. Submaximal Versus Maximal Exercise Loads Submaximal loading (exercise at moderate to low intensities): • At the beginning of an exercise program to evaluate the patient's response to resistance exercise • In the early stages of soft tissue healing when injured tissues must be protected • After periods of immobilization when the articular cartilage is not able to withstand large compressive forces or when bone demineralization may have occurred, increasing the risk of pathologic fracture • For most children or older adults • When the goal of exercise is to improve muscle endurance • To warm up and cool down prior to and after a session of exercise; or • During slow-velocity isokinetic training to minimize compressive forces on joints Near maximal or maximal loading (highintensity exercise): • When the goal of exercise is to increase muscle strength and power and possibly increase muscle size • For otherwise healthy adults in the last phase of a rehabilitation program after a musculoskeletal injury in preparation for returning to high-demand occupational or recreational activities • In a conditioning program for individuals with no known pathology • For individuals training for competitive weight lifting or body building Repetition Maximum One method of documenting the effectiveness of a resistance exercise program and calculating an appropriate exercise load is to determine a repetition maximum. This method was developed by DeLorme. A repetition maximum (RM) is the greatest amount of weight (load) a muscle can move through the available ROM a specific number of times. Repetition Maximum A repetition maximum can be used in a number of ways. DeLorme reported determination of a 1RM (the greatest amount of weight a subject could lift through the full ROM just one time) as a useful baseline measurement of a subject's maximum effort. From the 1 RM measurement a beginning load for exercise can then be calculated. 1RM; problems Is not safe for patients, for example, with joint impairments, patients who are recovering from or who are at risk for soft tissue injury, or patients with known or who are at risk for osteoporosis or cardiovascular pathology. Critics suggest that determination of a 1 RM for a particular muscle group involves a lot of trial and error and, therefore, may not be accurate if the patient fatigues before the 1 RM is identified. Some patients may not understand or may be apprehensive about exerting one maximum effort. Two Practical Ways 1) The higher RM value can be used as the baseline. If the patient was able to lift the selected weight 10 times, then the baseline measurement for future comparisons is a 10 RM. Two Practical Ways 2) 1 RM can be calculated from a conversion table. If the therapist prefers to use a 1 RM as the baseline measurement, the number of repetitions and weight can be cross referenced in a conversion table to determine a calculated 1 RM. According to one such conversion table, a 10 RM is approximately 75% of a 1RM. Some Conversion Methods • nRM = (1- 0.025n) 1RM • 1 RM = 5 RM x 1.15 • Calculate 1-RM Estimate using the Coefficient Factors. Weight lifted x the coefficient factor for the reps performed = 1 rep max Factor 1.057 1.148 1.247 1.318 1.393 1.513 Reps: 2 5 8 10 12 15 Volume In resistance training the 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 volume and intensity of resistance exercise. The higher the intensity (load), the lower the volume must be, and the converse is true. Repetitions and Sets The number of repetitions in a dynamic exercise program refers to the number of times a specific movement is repeated. More specifically, it is the number of muscle contractions performed to move the limb through a series of continuous and complete excursions against a specific exercise load. The "average" untrained adult, when exercising with a load that is equivalent to 75 % of the 1 RM, will be able to complete approximately 10 repetitions before needing to rest. At 60% intensity about 15 repetitions are possible and at 90% intensity only 4 to 5 repetitions are usually possible. No optimal number for strength training or endurance training has been identified. Training effects (greater strength) have been reported with the use of a 2 to 3 RM to 15 RM. Sets are a predetermined number of repetitions grouped together; sets are also known as bouts. After each set of a specified number of repetitions there is a brief interval of rest. As with repetitions, there is no optimal number of sets per exercise session. As few as one set and as many as six sets have yielded positive training effects. To Improve Muscle Strength Current recommendations are to use an exercise load that cause fatigue after 6 to 12 repetitions for two to three sets (6-12 RM). When fatigue no longer occurs after the target number of repetitions has been completed, the level of resistance is increased to once again overload the muscle. To Improve Muscle Endurance Training to improve local endurance involves performing many repetitions of an exercise against a sub maximal load. For example, as many as three to five sets of 40 to 50 or more repetitions against a light grade of elastic resistance might be used. Endurance training, because it is performed against very low levels of resistance, can and should be initiated very early in a rehabilitation program without risk of injury to healing tissues. Frequency Frequency in a resistance exercise program refers to the number of exercise sessions per day or per week. Frequency is dependent on other determinants, such as intensity and volume as well as the patient's goals, general health status, previous participation in a resistance exercise program, and response to training. Duration Exercise duration is the total number of weeks or months during which a resistance exercise program is carried out. Strength gains, observed early in a resistance training program (after 2 to 3 weeks) are the result of neural adaptations. For significant changes to occur in muscle, such as hypertrophy or increased vascularization, at least 6 to 12 weeks of resistance training is required. Rest Interval (Recovery Period) Rest is necessary to allow time for the body to recuperate from the acute effects of exercise, associated with muscle fatigue or to offset adverse responses, such as exercise-induced, delayed-onset muscle soreness. Rest intervals for each exercising muscle group are dependent on the intensity and volume of exercise. For example, between sets of moderate intensity and volume exercise (at an 8- to 12-RM level), a 30to 60-second rest period is common. With higher intensity, near-maximal loading (at a 3- to 5-RM level), a longer rest period before performing another set of the same exercise is necessary. Mode of Exercise The mode of exercise in a resistance exercise program refers to the form or type of exercise or the manner in which the exercise is carried out. Mode of exercise also encompasses the form of resistance, that is, how the exercise load is applied. For example, a patient may perform an exercise dynamically or statically or in a weight-bearing or non weight bearing position. Samples of Resistance Exercises Techniques of Resistance Training • Overload Principle – To improve strength, muscle must be worked at a level higher than it is accustomed to – Muscle will maintain strength if it is trained against a consistent resistance that it is accustomed to • Existence of current strength & will result in increased muscle endurance – Effective training requires a consistently increasing effort against progressively more resistant loads – In rehabilitation, rate of progression is determined by athlete’s response to specific exercise • Be mindful of pain and swelling when dealing with progression Types of Skeletal Muscular Contractions • Isometric • Concentric • Eccentric • Isometric Exercise – Capable of increasing muscle strength at specific joint angles • Exercise with no change in muscle length – May produce spikes in systolic blood pressure • Could cause life-threatening cardiovascular accident • To reduce this event to occur - REMIND the person to breath during the maximal contraction – Widely used in rehabilitation • Attempt to use positional or functional exercise – work at multiple angles throughout the range if possible – Contractions should be held for 10 seconds at frequency of 10 or more per hour – Utilized to enhance lift or activity at “sticking point” Sticking Point • Sometimes, there is a particular angle in the R.O.M at which smooth movement is difficult because of insufficient strength. This joint angle is referred to as a sticking point. • If strength can be improved at this joint angle, then a smooth, coordinated power lift can be performed through a full R.O.M Isometric Exercise and Strength Gain • An isometric contraction provides stabilization strength that helps maintain normal length – tension and force – couple relationships, which are critical for normal joint arthrokinematics. • Isometrics are capable of increasing muscular strength. However, strength gains are relatively specific to the joint angle at which training is performed. At other angles, the strength curve drops off dramatically because of a lack of motor activity at that angle. Aims To prevent or minimize muscle atrophy when joint movement is not possible due to external immobilization (casts. splints, skeletal traction) To activate muscles (facilitate muscle firing) to begin to reestablish 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 taskrelated needs • Progressive Resistive Exercise (PRE) – Exercises that work through a full range of motion – Isotonic or isodynamic contractions • Most popular & commonly used technique – Concentric (positive) vs. Eccentric (negative) • Greater force can be generated with eccentric due to lower number of motor units recruited allowing other motor units to be recruited to generate increased force • Oxygen use is much lower with eccentrics • Efficiency of eccentric exercise is higher than concentric exercise. Thus, it is more resistant to fatigue • Needs of the body – acceleration and deceleration • Must be able to control body movements – deceleration and eccentrics allows for this control Note: Although the term isotonic (meaning equal tension) has been used for many years to describe a dynamic muscle contraction against resistance that causes joint movement, application of this terminology is incorrect. In fact, when a body segment moves through a R.O.M, the tension that the muscle is capable of generating varies through the range as the muscle shortens or lengthens due to the changing lengthtension relationship of the muscle and the changing torque of the load; thus, force output does not remain constant. Therefore, "isotonic“ is not used to describe dynamic resistance exercise. Research has clearly demonstrated that the muscle should be overloaded and fatigued both concentrically and eccentrically for the greatest strength improvement to occur. When training specifically for the development of muscular strength, the concentric portion of the exercise should require 1-2 S, while the eccentric portion of the lift should require 2-4 S. Concentric/eccentric ratio should be approximately ½. – Free Weights vs. Exercise Machines • Advantages & disadvantages for both • Machines – Safety & easy to use – Constraints on motion & generally single plane of motion • Free weights – Do not restrict motion – Incorporates certain level of neuromuscular control – Stabilization decrease the amount of weight that can be lifted. – Surgical Tubing (Theraband) or Exercise Band • Allow for motion in multiple planes • Ability to perform more functional movement • Can be utilized with PNF & plyometrics – Variable Resistance • Change in force required at different angles to move a particular resistance • Greatest when joint is at 90 degrees • Accommodating resistance or variable resistance equipment changes resistance at different points in range • A number of exercise machine manufacturers have attempted to alleviate this problem of changing force capabilities by using a cam in its pulley system. • The cam is intended to alter resistance so that the muscle can handle a greater load, but at the points where the joint angle or muscle length is mechanically disadvantageous, it reduces the resistance to muscle movement. Whether this design does what it claims is debatable. • Progressive Resistive Exercise Techniques (PRE) – Terminology • Repetitions • Repetition maximum (RM) • Set • Intensity • Recovery period • Frequency • Recommended Techniques of Resistance Training – Must consider 4 areas • Amount of weight to be used • Number of repetitions • Number of sets • Frequency of training – The healing process must dictate the program! – Intensity is key – Multiple potential routines • Single set – 1 set 8-12 reps at a slow speed • Tri-sets – 3 exercises for 1 muscle group, 2-4 sets with no rest • Multiple sets – 2-3 warm-up sets with progressively increasing resistance followed by several sets at the same resistance • Superset – multiple exercises, 1 set of 8-10 repetitions or 1 or 2 exercises, with multiple sets of 8-10 repetitions • Pyramid – One set of 8-12 reps with light resistance, then an increase in resistance over 4-6 sets until only 1-2 reps can be performed. The pyramid can also be reserved going from heavy to light resistance. • Split routine – Workouts exercise different groups of muscles on different days – Circuit Training • Group of exercise (flexibility, callisthenic, strength, brief aerobic) • Used to increase strength or endurance • Move from one station to the next, performing exercise for a given time period or number of repetitions Progressive Resistance Exercises Progressive Resistive Exercise • Resistance training techniques for rehab – DeLorme’s program • Based on 10 RM – Set 1: 10 reps of 50% 10 RM – Set 2: 10 reps of 75% 10 RM – Set 3: 10 reps of 100% 10 RM Progressive Resistive Exercise • Resistance training techniques for rehab – Oxford technique • Set 1: 10 reps at 100% 10 RM • Set 2: 10 reps of 75% 10 RM • Set 3: 10 reps of 50% 10 RM – McQueen’s technique • Beginning/ intermediate: 3 sets x 10reps, 100% of 10 RM • Advanced: 4-5sets x 2-3reps, 100% of 2-3 RM Sander’s program • Was designed to be used in the advanced stages of rehabilitation and was based on a formula that used a percentage of body weight to determine starting weights. For example: • Barbell squat – 45% of body weight • Barbell bench press – 30% of body weight • Leg extension – 20% of body weight • Universal bench press – 30% of body weight • Universal leg extension – 20% of body weight • Universal leg curl – 10-15% of body weight • Universal leg press – 50% of body weight • Upright rowing – 20% of body weight Progressive Resistive Exercise • Resistance training techniques for rehab – Sander’s program- advanced • • • • Different % of body weight for different exercises Day 1: 4x5 100% 5 RM Day 2: 4 x5 100% 3 RM Day 3: 1x5 100% 5 RM 2x5 100% 3 RM 2x5 100% 2 RM Progressive Resistive Exercise • Resistance training techniques for rehab – Knight’s DAPRE program • Individual differences in rates at which patients progress • Set 1: 10 reps 50% RM • Set 2: 6 reps 75% RM • Set 3: max reps 100% RM • Set 4: max reps adjusted working weight DAPRE Adjusted Working Weight Number of Repetitions Performed During Third Set Adjusted Working Weight During Fourth Set Next Exercise Session 0-2 -5-10 Ib -5-10Ib 3-4 -0-5 Ib Same weight 5-6 Same weight +5-10 Ib 7-10 +5-10 Ib +5-15 Ib 11 +10-15 Ib +10-20 Ib Progressive Resistive Exercise • Resistance training techniques for rehab – Berger • Adjustable within individual limitations • Weight selected should allow 6-8 RM in each of three sets – Trial and error – 60-90 second recovery period – Progress up about 10% of current weight For rehabilitation Purposes – Base program on pain and healing process – Should be performed on a daily basis initially – Reduce workout to every other day as progress in healing process is made and pain and swelling is no longer an issue (at least 3 times but no more than 4 times per week). • Isokinetics as a Conditioning Tool – Maximal effort for maximal strength gains – Dynamometer will move at a set speed whether maximal or half of maximal effort is put forth • Athlete can cheat with machine and not put forth the effort – Not cost effective • Isokinetics in Rehabilitation – – – – Gained popularity in rehabilitation during the 1980’s Provide objective means of athlete/patient evaluation Training at fast vs. slow speeds Functional speeds Isokinetic Exercise • Involves muscle contractions where length change of muscle is set at a constant velocity. • Maximal resistance throughout the range of motion. • The key is not the resistance but the speed at which resistance can be moved. • Variety of machines/manufacturers are available • Can be used with eccentric & concentric exercise Isokinetic Training Principles • Disadvantages: 1)Cost 2) Although isokinetic training affords a spectrum of velocities for training, the speed of limb movement during many functional and sports-related activities far exceeds the maximum speed settings available on isokinetic equipment. 3) Isokinetic exercise usually isolates a single muscle or opposite muscle groups, involves movement of a single joint, is uniplanar, occurs in an open-chain (non weight bearing) and constant velocity. (not so functional). Plyometric Exercise • Encompass a rapid stretch of muscle eccentrically followed by a rapid concentric contraction to facilitate the development of explosive power • Greater stretch relative to resting length = greater resistance muscle can overcome – Speed of stretch is emphasized over magnitude • Used to develop eccentric control of dynamic movements • Exercises should be performed technically correct Core Stabilization Strengthening • Fundamental component of rehabilitation • Strengthening of core (lumbo-pelvic complex) • Used to – Improve dynamic postural control – Ensure appropriate muscular balance & joint movement about the core – Improve neuromuscular efficiency and expression of dynamic functional movement • Provide optimal stabilization of kinetic chain and balanced muscular functioning throughout the chain Training for Muscular Strength vs. Muscular Endurance • Strength and endurance are closely related – As one improves, the tendency is for the other to do the same • For strength development – Heavier weight and low repetitions should be used • Endurance training – Lighter weight and high repetitions (10-15) are suggested Resistance Training Differences Between Males & Females • Females tend not to develop significant muscle bulk due to reduced levels of testosterone • While bulk generally does not increase, muscle tone will increase through training in females • Gains are primarily neuromuscularly related & tend to plateau for females • Males tend to continue developing strength through increased bulk following the neuromuscular strength gains • Strength/Body Weight Ratio – Females tend to have a lower ratio due to higher levels of body fat • Absolute strength differences – Reduced when body size & composition are compared – Leg strength can actually be stronger in females with upper extremity strength greater in males Resistance Training in Young Athletes • Same principles can be applied to young athletes • Much debate sociologically & physiologically • If properly supervised, young athletes can make improvements in all areas of fitness – Pre-pubescent child will experience gains in muscle strength without muscle hypertrophy • Resistive exercise should be integrated into a young athlete’s rehabilitation • Close instruction & supervision is necessary – Base on extent of maturation – critical to effectiveness Specific Resistive Exercises Used in Rehabilitation • Goal of program – To regain and possibly increase specific muscle strength – Increase efficiency of movement • Variety of exercise modes can be utilized to achieve goals Progression of a Resistance Training Program Factors Progression Intensity (exercise load) Submaximal ~ maximal (or nearmaximal) intensity Low load ~ high load Body position (non weight – or weightbearing) Variable: depending on pathology and impairments, weight-bearing restrictions (pain, swelling, instability) and goals of the rehabilitation program Repetitions and sets Low volume~ high volume Frequency Variable: depends on intensity and volume of exercise Type of muscle contraction Static ~ dynamic Concentric and eccentric: variable progression Progression of a Resistance Training Program Factors Progression Range of motion Short arc~ full arc Stable portion of range~ unstable portion of range Plane of movement Uniplanar ~ multiplanar Speed of movement Slow ~ fast velocities Neuromuscular control Proximal~ distal control Functional movement patterns Simple~ complex Single joint~ multi joint Proximal control~ distal control ACSM Strength Guidelines • Frequency = 2-3 days/week • Intensity – 85% of max for strength – 75% of max for muscular power + (method) – 50% - 65% of max for muscular endurance • Time = – 30 - 90 sec. per set / 8 - 12 reps per set – work to rest ratio 1:4 • Type = resistance type Closed & Open Kinetic Chain Exercises • To a large extent the term CKC exercise has come to mean "weight-bearing exercise." However, although all weightbearing exercises involve some elements of CKC activities, not all CKC activities are weight-bearing. Muscle Actions in the Kinetic Chain • Muscle actions that occur during OKC activities are usually reversed during CKC activities. In OKC exercise, the origin is fixed and muscle contraction produces movement at the insertion. In CKC exercise, the insertion is fixed and the muscle acts to move the origin. Kinetic chain Steindler: In mechanics, it describes a series of sequentially activated segments. In human body, it is the combination of several successively arranged joints constituting a complex motor unit. These series, or chains, can occur as either of two primary types: open or closed. Open kinetic chain An exercise or movement pattern where the distal aspect of the extremity is not fixed to an object and terminates free in space. Examples: waving the hand, movement of the foot during the swing phase of gait, the seating knee-extension exercise, straight leg raises Closed kinetic chain An exercise or movement pattern where the distal aspect of the extremity is fixed to an object that is either stationary or moving. In other words, the distal segment remains in constant contact with the surface, usually the ground or the base of a machine. A condition or environment in which the distal segment meets “considerably” external resistance that restrains free motion. True closed kinetic chain movement patterns do not technically exist in the human body, except in isometric exercises where no movement of proximal or distal segments occur. In clinical situations, an exercise in which resistance is placed through the distal aspect of the extremity and remains fixed to the extremity. Example: standing squat (both front and back), Leg Press, Lunge Bilateral closed-chain resisted hip and knee extension OKCE concentrates on a strong quadriceps contraction, which will strengthen the quadriceps and restore quadriceps power output. CKCE concentrates on a co-contraction of the quadriceps, hamstrings, hip flexors, soleus, and gastrocnemius muscles. Also this is a multi-joint movement, which focuses on the knee, hip, and ankle. CKCE are labeled as being "sport specific movements" . One exercise whose classification as open or closed kinetic chain exercise is uncertain involves stairclimbing machines, where the distal aspect of the lower extremity remains fixed to an object (the pedal) that is constantly moving during exercise. Similarly, riding a bicycle involves a closed system, but many clinicians and researchers argue that the movement of the pedal and the trivial resistance level occasionally encountered while pedaling do not clearly qualify that exercise as a closed kinetic chain exercise. Characteristic Open kinetic chain Closed kinetic chain Stress pattern Rotary Linear Number of joint axes One primary Multiple Nature of joint segments Number of moving joints Planes of movement One stationary, the Both segments move other mobile simultaneously Isolated joint motion Multiple joint movement One (single) Multiple (triplanar) Muscular involvement Isolation of muscle or muscle groups, minimal muscular co-contraction Often nonfunctional Movement pattern Significant muscular co-contraction Significant functionally oriented movement patterns Other Commonly Used Terms Single-joint Versus Multiplejoint Exercise (Joint multiplicity) Boundary Condition and Load The term single joint versus multiple joint have been used to describe exercises based on the number of joints being exercised. Single-joint exercises correspond closely with traditional open kinetic chain exercise movements such as the biceps curl and seated knee extension. Single-joint exercises are also commonly referred to as joint-isolation exercises because these types of exercises isolate activity at one particular joint and often isolate particular muscles or groups of muscles. Multiple-joint exercises correspond closely with exercises that are commonly classified as closed kinetic chain. Movement occurs at multiple levels with muscular co-contraction during these exercises, and the ability to exercise numerous segments and muscle groups simultaneously is their primary benefit. Dillman et al. (1994) proposed an alternative method of classifying exercises based on mechanics. They used the boundary condition and the presence or lack of an external load as the two criteria in the classification scheme. The boundary condition is termed either fixed or movable, rather than closed or open. An external load may or may not exist with the exercise. Therefore Dillman et al. proposed three categories of exercise: Fixed with external load (FEL). which most closely corresponds with the classic definition of a CKC exercise. Examples: push-up or squat. Movable boundary with no external load (MNL). This condition corresponds closely with a true OKC exercise. Examples: raising the arm or extending the lower leg with no resistance applied. Movable boundary with external load (MEL). This condition attempts to classify the gray area in the open/closed chain classification and the single-/multiplejoint classification system. Examples: bench-press exercise for the upper extremity and a stair-climbing or leg-press exercise for the lower extremity. Characteristics of OKC Exercises Distal end of the extremity is free in space. Distal end of the extremity is not in contact with a fixed object. Movement pattern is characterized by rotary stress in the joint. Joint movements occur in isolation. Muscle recruitment and movements are isolated. Joint axis is stable during movement patterns. The proximal segment that forms the joint is stable, and the distal segment is mobile. Motion occurs distal to the instantaneous axis of rotation. Movement pattern is often nonfunctional. Movement causes shear forces in the joint. Artificial loading of the muscles and joints occurs. Velocity is predetermined by exercise equipment if isokinetiks is used. There is artificial means of stabilization. Testing is not typically functional. Characteristics of CKC Exercises Distal end of the extremity is fixed to something. Movement pattern is characterized by linear stress in the joint. Multiple joint movements occur simultaneously. Multiple muscles are recruited. The primary joint axis is transverse. Both segments that form the joint move simultaneously. Movement patterns are functional. Movement causes compressive forces in the joint. There is co-contraction of the muscles surrounding the joint. Movement often occurs in multiple planes simultaneously. Muscles and joints are physiologically loaded. Velocity is variable through a movement pattern. There is no artificial stabilization. Loading is physiological and provides normal proprioceptive or kinesthetic feedback. Performance of movement is not inhibited by design of equipment. Movement causes compression of the joint surfaces, thereby increasing joint stability. Testing and exercises are more functional. Summary of Benefits for CKC Increased joint compression forces Increased joint congruency and thus stability Decreased shear forces Decreased acceleration forces Large resistance forces Stimulation of proprioceptors Enhanced dynamic stabilization (co-activation) Protect healing soft tissue Characteristics of OKC exercises Increased acceleration forces Decreased resistance forces Increased distraction and rotational forces Increased deformation of joint and muscle mechanoreceptors Concentric acceleration and eccentric deceleration forces Promotion of functional activity These are typical of non-weight-bearing activities. External forces During Kinetic Exercises there are typically two kinds of external forces: shear and compression. Shear force, is the force which causes a disruption of the ACL by shifting the tibia anteriorly and the femur posteriorly. This is caused from the strong contraction of the quadriceps, which is typical of the Open Chain Exercise. This force, which is placed on the front of the knee, places a large amount of stress on the ACL. Compression force is caused from a strong external force placed on the knee, which pushes the head of the femur together with the head of the tibia. This external force causes stability in the knee and a decrease in shear force. Compression forces are common in Closed Chain Exercises. Closed kinetic chain exercises serve to minimize the tibiofemoral shear forces through both axial loading and hamstring coactivation. Several authors and clinicians have offered additional or alternative categories for classification of resistance activities to eliminate the ambiguity. One suggestion is to add a category dubbed partial kinetic chain to describe exercises in which the distal segment (hand or foot) meets resistance but is not absolutely stationary, such as using a stepping machine or slide board. The term closed kinetic chain is then reserved for instances when the terminal segment does not move. To date, this additional term has not been widely used in the literature or in the clinical setting. Comparison Closed kinetic Vs. Open kinetic chain exercises Isolation of Muscle Groups Open-chain testing and training identifies strength deficits and improves muscle performance of individual muscles or muscle groups more effectively than closed-chain exercises. The possible occurrence of substitute motions that compensate for and mask strength deficits of individual muscles is greater with closed-chain exercise than open-chain exercise. Control of Movements During open-chain resisted exercises a greater level of control is possible with a single moving joint than with multiple moving joints as occurs during closedchain training. In open-chain exercises stabilization is usually applied externally by a therapist's manual contacts or with belts or 'straps. In contrast, during closed-chain exercises the patient most often uses muscular stabilization to control joints or structures proximal and distal to the targeted joint. Greater levels of control afforded by open-chain training are often advantageous in the early phases of rehabilitation. Joint Approximation Almost all muscle contractions have a compressive component, which approximates the joint surfaces and provides stability to the joint whether in open or closed-chain situations. Joint approximation also occurs during weight bearing and is associated with lower levels of shear forces. This has been demonstrated in the knee (decreased anterior or posterior tibiofemoral translation) and possibly the glenohumeral joint. The joint approximation that occurs with the axial loading during weight bearing is thought to cause an increase in joint congruency which, in turn, contributes to stability. Coactivation and Dynamic Stabilization Since most closed-chain exercises are performed in weight- bearing positions, they stimulate joint and muscle mechanoreceptors, facilitate coactivation of agonists and antagonists (cocontraction) and subsequently promote dynamic stability. During a standing squat, for example, the quadriceps and hamstrings are thought to contract concurrently to control the knee and hip respectively. In the upper extremity, closed-chain exercises in weight-bearing positions are thought to cause coactivation of the scapular and glenohumeral stabilizers and, therefore, to improve dynamic stability of the shoulder complex. Proprioception, Neuromuscular Control, and Balance After soft tissue or joint injury, proprioception are disrupted and alter neuromuscular control. Reestablishing the effective and efficient use of sensory information to initiate and control movement is a high priority in rehabilitation. Closed-chain training provides greater proprioceptive and kinesthetic feedback than openchain training. Theoretically, because multiple muscle groups that cross multiple joints are activated during closed-chain exercise, to control motion more sensory receptors in more muscles and intra-articular and extra-articular structures are activated than during open-chain exercises. The weight-bearing element (axial loading) of closed chain exercises, which causes joint approximation, is believed to stimulate mechanoreceptors in muscles and in and around joints to enhance sensory input for the control of movement. Carry-Over to Function Consistent with the principle of task-specific training, exercises should be incorporated into a rehabilitation program that simulates the desired functions and prepares the patient for the functional tasks. For example, squatting exercises in standing have been shown to enhance performance of a jumping task more effectively than open-chain isokinetic knee extension exercises. Parameters and Progression of ClosedChain Exercises 1) % Body weight Partial full weight-bearing (UE:wall push-up modified prone push-up prone push-up) Full weight-bearing + additional weight (Weighted vest or belt, handheld or cuff weights, elastic resistance) 2) Base of support Wide narrow Bilateral unilateral Fixed on support surface surface sliding on support 3) Support surface Stable unstable/moving (LE: Floor rocker board, wobble board, sideboard, treadmill) (UE: Floor, table or wall rocker or side board, ball) Tight soft (Floor, table carpet, foam) Height: ground level increasing height (Low step high step) 4) Balance With external support no external support Eyes open eyes closed 5) Exclusion of limb movement Small Short-arc large ranges full-arc (if appropriate) 6) Plane or direction of movement Uniplanar multi planar Anterior posterior diagonal (Forward walking retrowalking; forward step-up backward step-up) Sagittal frontal or transverse (forward-backward sliding side to side sliding; forward or backward step-up lateral step-up) 7) Speed of movement or directional changes Slow fast Closed Kinetic Chain Exercises for lower extremity Minisquat performed in 0- to 40-degree range. Standing Squat Standing wall slide Wall Slide Leg-press exercise Leg press Lunges are done to strengthen quadriceps eccentrically Stair master stepping machine Lateral step-ups Terminal knee extensions using surgical tubing resistance Tubing resistance exercise Stationary bicycle BAPS board exercise Balance board Mini-Trampoline Fitter Lunge with medicine ball Wall slide with medicine ball Slide board training Slide board Rehabilitation program Acute phase: Aims: motion, dynamic joint stability, decreased muscle atrophy (VMO) Standing mini squats (0-30 degree) step-ups (low steps to high steps) Forward lunges (length & depth) Mini squats (progressed) wall slides lateral Sub-acute phase Squat 0-60,70, step-ups &lunge include lateral movement and exercise tubing resistance (forward, backward and either side) Initiation of cone drills Uneven surfaces (trampoline, fitter, balance board) Dumbbells of different weights Advanced phase: Squats and lunges on uneven surfaces. Cone drills with high speed and duration. Also with medicinal balls Slide boards Closed Kinetic Chain Exercises for upper extremity Weight shifting. A, Standing B, Quadruped C, Tripod D, Opposite knee and arm Weight shifting. A, On a BAPS board B. On a wobble board C. On a Plyoball Push-ups done on a Plyoball Push-ups done on a stair climber Press-ups Weight shifting Wall push-up Modified push-up Using elastic tubing Tripod using dumbbells Modified push-up Push-up with balls Push-up with fitter Versa climber Push-up (tripod position) Upper body isokinetics Rehabilitation program Acute phase: Punching machine Isometric retraction (middle trapezius, rhomboid) Isometric press-ups Subacute phase: Resisted quadraped exercises (roller, fitter, thera-band) Tripod (simple, elastic tubing, dumbbells, balls) Opposite knee and arm Advanced phase: Push-ups with hands on the balls Balance board, balance system, movable platform, lateral step-ups Lateral walking on hands on treadmill or stair stepper Thank You