Monograph 6
The Need for Adequate Conditioning By R. C. Schafer, DC, PhD, FICC
Manuscript Prepublication Copyright 1997Copied with permission from ACAPress
Introduction
Work Conditioning
Conditioning in Sports
Initial Conditioning: Warm-up and Stretching
Clinical Considerations in Soft-Tissue Rehabilitation
Remobilization
The Anatomical Movers
Exercise Common Sense
General Rules of Exercise with WeightsProprioceptive Neuromuscular Facilitation Techniques
Methodology
Applied Oscillation
Conditioning and Posttraumatic Exercise Regimens
Acquisition of Strength
Structured Exercise Regimens
Passive Exercise
Muscle Training by Resistance Exercise Equipment
Home Exercise Prescriptions
References and Bibliography
INTRODUCTION
To develop good physical performance and prevent injury, conditioning programs should have four major components: (1) warm-up and stretching, (2) the development of muscular strength, (3) the development of joint flexibility, and (4) the development of endurance (both somatic muscular and cardiorespiratory).
Experience has shown that conditioning is one of the most important ways to prevent injuries by strengthening tissues, keeping the joints flexible, improving physiologic tone, reducing excessive weight, and reducing fatigue. A well-conditioned person will have greater endurance, strength, and stamina.
An important factor in preventing injuries is the development of an appropriate level of physical fitness. Haycock feels that "conditioning is the equivalent of physical fitness". To be "fit" is to be equal to the demands, whether it be work or play. Yet the attending physician should keep in mind that to be physically fit for one occupation, sport, or position does not imply adequate fitness for another. In athletics, for example, certain sports require greater levels of fitness of different anatomic parts, and this must also be realized. A marathoner will traditionally have poor upper body development as compared with a discus thrower who will have superior upper-body fitness.
Work Conditioning
It should be obvious to any clinician that different patients, injuries, and working conditions require different forms of rehabilitative "work hardening." Work hardening is a term used in industrial medicine to refer to preparing an injured worker to a level of productive physical competence to return to work. Thus, it is goal specific, job directed, and program intensive (structured timeframe). Common procedures include structural and functional profiling, psychophysical modeling, goal definition, vocational rehabilitation, and ergonomic analysis.
Conditioning in Sports
To maintain acquired conditioning in athletics, each team member and prospective member should be provided with a regimen for preseason conditioning, and each player should be required to adequately warm-up before each competition or practice. As a general rule, at least 3 weeks of progressive practice should be held before the first competition. During the off season, two or three moderate workouts a week are usually enough to prevent much deterioration.
When an athlete is physically capable of performing a sport with optimal efficiency, he or she can meet both physiologic and biomechanical demands placed upon the body. This is true not only for typical performance demands but also for critical situations.
A low level of physical fitness leads to fatigue that tends to impair the conditioned reflexes involved in physical skills. However, skill alone will not protect against the effects of overexertion if activity is carried beyond the limit of one's level of physical fitness. Conditioning enhances flexibility, agility, speed, endurance, and strength. These are safeguards having positive benefits to one's level of general fitness and performance.
Initial Conditioning: Warm-up and Stretching
As a ground work in athletic training or before any strenuous physical labor, a progressive warm-up period is a requisite. It consists of the entire body being put through stretching or flexibility exercises, and then of specific body parts essential to the sport and position. The benefits of adequate warm-up are also important before engaging in any stressful physical activity in the workplace or during leisure recreation.
The value of calisthenics in athletics has long been debated from a physiologic standpoint, and the final answer is still not known. The weight of evidence is empirical. However, we do know that properly designed and performed exercises call into action little-used muscle groups, strengthen them reasonably, and contribute to flexibility. Repetition increases muscle tone and enhances cardiovascular efficiency.
The length of a warm-up period varies with the individual and anticipated demands. Usually, it is said to be sufficient when perspiration arises. Warm-up should never result in fatigue, but it should present a renewed sense of joint "freedom." Careful supervision should be maintained during the warm-up to prevent the eager athlete from overdoing and then becoming discouraged, sore, or strained.
Acclimatization to a change in environment or altitude, temperature changes, and humidity changes also influence an athlete's performance. The well-trained athlete generally adapts faster than one out of condition.
CLINICAL CONSIDERATIONS IN SOFT-TISSUE REHABILITATION
Clinicians are obligated to seek answers to many questions concerning human dynamics for it is impossible to separate structure from function. This requires knowledge of how the nervous system integrates proprioceptive input and coordinates activity of the musculoskeletal system so that each unit involved contributes its function properly. Thus, a primary concern within health care in its quest to maintain physical fitness and optimal reserves is the integration of neurophysiologic and biomechanical information.
Remobilization
The term "remobilization" in medical literature generally refers to conditioning regimens following weeks in immobilization such as a plaster cast. Chiropractors realize, however, that a potentially active joint that is not moved through its normal ranges of motion in daily activities by sedentary people or an active joint restricted by the effects of posttrauma fibrosis presents with the same picture. In other words, "why" a joint is not moved is not pertinent clinically. The processors of deterioration do not differentiate among the reasons for insufficient use.
The chiropractic profession has pioneered the art of articular remobilization in spinal and extraspinal joints. Joint mobility allows force to be transmitted through a greater range of motion. Passive exercise and remobilization techniques stimulate all types of mechanoreceptors of a joint. This is necessary to ignite impulses at least at the afferent part of the normal circuit. By mimicking joint movement by a passive force, the object is to spur the "memory" of this normal path in the spinal cord governing active reflex and higher CNS actions. Without proper mechanoreceptor input, trophic efferent impulses cease and bone, muscle, tendons, articular cartilage, capsules, and ligaments degenerate.
The neurologic circuit benefits from remobilization are only part of the picture. Recent joint research has done much to prove what chiropractors have learned empirically for many decades. Harrelson gives much support that joint tissues respond favorably to mechanical stimuli and that structural modifications are noted soon after exercise. Levick shows that interarticular motion also enhances transsynovial nutrient flow. Akeson and colleagues found that fibroblasts and chondrocytes interpret physical forces to influence their rate and synthesis, and extracellular degradation of connective-tissue matrix components is similarly controlled.
Donatelli/Owens-Burkhart supply evidence that movement maintains joint lubrication and critical fiber distance within the matrix and ensures an orderly deposition of collagen fibrils. They also state that forceful manipulation that breaks intracapsular fibro-fatty adhesions may be necessary to restore a full range of motion. Zarins' studies concluded that muscle regeneration begins within 3-5 days after initiating a reconditioning program and that both slow-twitch and fast-twitch muscle fibers can recover completely. When passive mobilization is assisted by the patient to some degree to produce a contraction, the results reflect Tucker and associates' findings that protein synthesis responds quickly to major changes in muscle contraction by a rapid increase in synthesis.
Mobilization, however, is not the complete answer for it does not stimulate the deep-pressure compression-type mechanoreceptors. Hall shows that even with mobilization, deterioration will continue (especially in articular cartilage) until weight-bearing is allowed. Although ligament strength depletes with immobilization, mobilization has no significant effect on building ligament or tendon strength. This requires endurance-type exercise. Several authorities report that it can take from 1 to 3 years for a Grade III sprain to heal to its preinjury status, depending on the extent of overstress and the history of repeated trauma.
Although the degree to which joint flexibility can be influenced by training is controversial, there is no doubt that latent potential should be developed to its optimal, but not extreme, limits in certain sports and occupations. However, mobilization should never be carried beyond its anatomical limit. While some pain may be self-justified in pursuits of endurance development, it is never justified in terms of joint flexibility.
Since forceful passive mobilizing exercises may create damage, active mobilizing exercises are preferred. Exceptions to this are proprioceptive neuromuscular facilitation techniques, which consist of warming muscle groups before stretching by applying a strong isometric effort at the initial point of full stretch as a partner offers light resistance. With this technique, the pertinent muscles appear to accept further stretch because of partner assistance and the active contraction of muscles on the opposite side of the joint. Such isometric "priming" usually shows that the joint in question can be moved to a further end-position within the range of comfort.
The Anatomical Movers
Posttraumatic muscle rehabilitation is most efficient when specifics are known, but properly analyzing the anatomical movers at the point of performance has been a difficult task until recently. Chun developed a method that, in biomechanical terms, depends on the principle that a body segment moves along the direction of the resultant of the applied separate forces. In other words, the segment must move along the direction of muscle tension, passive tissue resistance, and external forces applied on the segment such as gravity, elasticity of the equipment used, friction, muscular tension of opponents, etc. Generally, the direction of the segmental motion and the external forces is known. Thus, the direction of muscle tension can be determined, as well as the main muscles responsible for the movement.
Chun states there are usually three situations in which the determination of the principal movers of human motion is possible:The direction of segmental motion would be classified as opposite to the direction of the external forces (ie, gravity, etc). This indicates that the movers are located on the same anatomical side as that of the segmental motion.
Slow moving segmental actions occur in the same direction as that of the external forces. Consequently, the movers will be located on the opposite side of the segmental motion.
Rapid segmental movements also occur in the same direction as that of the external forces. The movers now represent muscles lying on the same side of the segmental motion.Keeping these three points in mind during the prescription of mobilizing or strengthening exercises will greatly enhance the attainment of clinical goals.
EXERCISE COMMON SENSE
Within the last 20 years, exercise and its role in physical fitness has advanced from a trade to a science. An early product of the mass of data acquired has been the development of "body-building" apparatus. In recent years, however, we learned that many assumptions have been erroneous.
This paper will not emphasize the use of sophisticated exercise equipment. The first reason is that most in common use are expensive and too specific for the type injuries generally seen and for the common patient. Prolonged specificity in muscle action is not natural.
Compare outdoor bicycling with use of a stationary bicycle. The fixed apparatus is fine for exercising hips in pure flexion and extension and stimulating activity of the hamstrings and calves and to a lesser degree the quadriceps and glutei. However, the plane of action is fixed -and this is not comprehensive. In riding a mobile bicycle, one must maintain balance, swerve to miss a stone in the path, bend laterally when turning, constantly shift one's center of gravity, etc. One often must pedal uphill, downhill, and around corners and obstacles. This requires use of more than the large muscles of the thigh and leg. It also mandates use of the oblique abductors and adductors of the hip, knee, and ankle, and almost all large and small muscles of the trunk and upper extremities to a considerable degree. This is natural exercise (alternating isotonic, isometric, and stretching) and promises greater benefit in building healthy soft-tissue tone and strength.
The second reason is that the use of apparatus is extremely boring except to the type of person who enjoys monotonous activity such as working on an assembly line or pulling the lever of a drill press all day. For most people, using an exercise machine or lifting weights is a bore. Spending a morning digging, planting, weeding, chopping, mowing, building something, or painting is fun in comparison to an hour at the "fitness center."
Watch how many people "workout" after the bell of a timer has rung! Walking a golf course, playing a friendly game of tennis, or swimming are usually welcomed activities. Taking a hike with a loved one is fun; walking a treadmill is monotonous for most of us. Boring activity is resented and soon discarded.
Professional athletes motivated by the promise of a million-dollar contract and stardom, of course, are exceptional. They dance, grunt, sweat, and repress pain to the beat of a different drummer.
Studies also show that (1) exercise bouts at 60% of maximum are more beneficial than regimens at 80% of maximum, (2) whole body exercise is more beneficial to fitness and excess fat loss than exercise of a part, and (3) pulse taking to acquired a certain level is a waste of time because some people show little change regardless of effort within normal ranges.
General Rules of Exercise with Weights
Following are some general rules in prescribing and supervising therapeutic exercise that have been gleaned from several authorities.
Attire. Clothing, nonrestrictive underwear, socks, and shoes appropriate for exercise should be worn.
Conditioning. A warm-up period of brief jogging and general stretching exercises should precede each weight-moving session. A postexercise cool-down period of progressively lightened exercise is equally as important.
Posture. Ideal posture should be strived for when exercising.
Style. A load should be moved in a smooth manner from a prestretched position and briefly halted in the position of full muscle contraction. Jerking motions should be avoided.
Speed. Speed should be moderate, not too fast or too slow. Negative work should take about twice the time as positive work.
ROM. Range of motion should be as great and as varied as possible in the routine.
Loading. The load should be heavy enough to require a maximum intensity of contraction (to the point of failure) after several (8-12) repetitions.
Timing. A high-intensity session every other day is just as effective as a daily session. It also offers the benefit of interval recovery.
Sequence. Large muscles should be worked first, small muscles last.
Neuromuscular Re-Education. The rehabilitating patient should be allowed to perform as normal function is possible in daily activities without interfering with the healing process.
PROPRIOCEPTIVE NEUROMUSCULAR FACILITATION TECHNIQUES
The techniques that fall under the heading of proprioceptive neuromuscular facilitation (PNF) techniques are special stretching maneuvers designed to enhance neuromuscular responses through proprioceptor stimulation. The goal is to reduce sensory activity through spinal reflexes to relax muscles to be stretched.
Knott/Voss, Moore/Hutton, and Sullivan and associates have done much to perfect these techniques, which are based on Sherrington's principle of reciprocal innervation; ie, relaxation of a muscle being stretched (the agonist) through voluntary concentric contraction of its antagonist, but PNF should not be applied until hypermobility (joint instability) and acute inflammation has been corrected or until fractures have healed. It is contraindicated in the presence of bone disease (eg, malignancy, advanced osteoporosis, ossified RA joint).
PNF is beneficial in cases of joint adhesions, spasms, contractures, deranged articular cartilage, taut capsules, and various end-feel abnormalities related to soft-tissue fixation (fibrosis) effects. It is an excellent method to distract impacted tissues and enhance articular lubrication.
Methodology
Before PNF is performed, the patient should be in a comfortable relaxed position with the involved joint in a loose-packed position. The part should be thoroughly examined before any manipulation is attempted. Rings and other jewelry should be removed from the part to be stretched.
Three common PNF techniques are the contract-relax, hold-relax, and slow-reversal hold-relax. In each of these techniques, firm stabilization must be provided, movements are made in a smooth manner, and motion is halted before pain is induced. Pain initiates a protective spasm. Whenever possible, a loose-packed joint should be maintained by applying distraction with the stabilizing hand.Contract-Relax Technique. The body part to be stretched is passively moved into the agonist pattern to the end of the physiologic ROM. At this point, the subject isotonically contracts the involved muscles into the antagonistic pattern against the strong manual resistance of the doctor or therapist. After relaxation occurs, the body part (eg, limb) is again moved passively into as much ROM as possible. This maneuver is repeated several times and then followed by active exercise. Thus, the purpose is to increase joint ROM in an agonistic pattern by using consecutive isotonic antagonistic contractions.
Hold-Relax Technique. This procedure is similar to the contract-relax method described above but motion is not allowed on isometric contraction. This is beneficial when spasm and pain accompany restricted joint mobility. The subject is instructed to gradually increase the intensity of each successive contraction. Thus, the purpose is to initiate isometric contraction of shortened muscles against complete resistance of the doctor or therapist.
Slow-Reversal Hold-Relax Technique. In this procedure, the body part is slowly moved several times into an agonistic pattern to the point of painless block and then passively returned to the neutral position. Thus, like the hold-relax maneuver, this technique applies the reciprocal innervation principle. Following several passive stretches, isometric contraction is initiated, relaxation occurs, and then more passive stretch is applied.
Applied Oscillation
Once the basic techniques of PNF have been mastered, manual oscillations (vibration-like movements) can be added when the part is near its physiologic limit. Small-amplitude oscillations near the point of end-feel or large-amplitude oscillations well within the functional ROM (never at its limit) are extremely helpful in joints limited by pain. Small-amplitude oscillation at the end of joint-play, large-amplitude oscillation stopping at the physiologic limit, and a short high-velocity chiropractic thrust stopping at the anatomical limit are beneficial in stretching painless restrictions.
The effect of oscillation is to dynamically fire mechanoreceptors to decrease muscle tension. Also, the fast-conducting fibers are stimulated to block impulses from the small pain-conducting fibers, according to the Gate Theory. Wright/Johns and Kaltenborn describe the neuromechanisms involved.
CONDITIONING AND POSTTRAUMATIC EXERCISE REGIMENS
Strength has many definitions. A general one states it as the maximum force that can be exerted by a muscle. In discussing strength, however, the terminology used is often confusing. The phrase isometric (equal in length) strength refers to muscle activity occurring without muscle shortening. Isotonic (equal in tone) strength means muscle activity with shortening of the muscle. Both of these general terms are misnomers in that there is a degree of length change in isometrics due to tendon stretching, and normal tone is influenced in isotonics by altered mechanical advantage and resistance.
Acquisition of Strength
Strength is acquired through training requiring repetition against increasing resistance. Thus, it is the effect of all-out effort against resistance. It is specific to a muscle or muscle group and specific to that angle at which the exercise occurs. Thus, to be strong at every angle, training must be throughout the range of joint motion. As motion requires synchronized body parts, all parts must be trained to be strong and have adequate endurance.
From a general viewpoint, new or lost strength can be acquired in three ways:1. Isometrically. by exercises done against resistance in a manner that body movement or joint angle are restricted (eg, pushing against a wall). Muscle involved maintains a fixed length, with tension generated equal to the resistance encountered. Isometric exercise sometimes offers a short cut to goals of equivalent repetitive drudgery, but it is inefficient in building strength at multiple joint angles. In the early phase of rehabilitation, it may be the only type of exercise permitted and always is preferable to no exercise at all.
2. Isokinetically. by exercises of a constant velocity against resistance that adapts to the angle of a joint (eg, Orthotron or Cybex II equipment). Isokinetic exercise uses variable resistance in which the speed of motion is fixed but the resistance varies to accommodate the input force (eg, manual resistance, Cybex, Biodex equipment). These exercises are used primarily to rehabilitate to the point of normal strength, after which other forms of exercise are used. In isokinetic exercise, work is done at a set speed with resistance matching the input of force at that speed. As input changes, resistance changes to match the input but speed remains constant. A person's muscular resistance is met with a proportional amount of resistance through full agonist and then antagonist activity.
3. Isotonically. by exercises against resistance in a manner that body movements are allowed (eg, weights and weight machines, spring or friction devices). In pure isotonic exercise, muscle length changes causing or resisting a change in joint angle and resistance remains constant while velocity is inversely proportional to load. Both eccentric and concentric contractions can be achieved. Common nonequipment (unaided) exercise regimens for developing muscle strength and endurance include sit-ups, bar chinning, cross-country jogging, push-ups, spinal extensions, rope climbing, and half-knee bends. Dynamic exercise may be (a) isotonic in which fixed weight is moved through a ROM (eg, ankle weights); (b) variable resistance in which resistance varies in a fixed ration through a full ROM (eg, Nautilus, Eagle equipment).
Positive vs Negative Isotonics. Isotonic exercise can be positive or negative. In a positive (concentric) contraction, muscle tension develops, muscle length shortens, and a resistance is overcome. In a negative (eccentric) contraction, muscle tension develops, muscle length increases, and a resistance is relieved. Thus, when a weight is lifted, positive work is accomplished; when a weight is lowered, negative work is fulfilled. A common example of positive and negative exercise is in chinning a bar, which requires positive strength, and then slowly lowering the body (load), which requires negative strength.
Positive work requires twice as much oxygen (but often half the time) than that of negative work. Negative work has little effect on cardiovascular conditioning, but it has shown to be far superior in strength development. For an unknown reason, muscle soreness is more profound after a bout of negative exercise than positive exercise. This likely originated the "no pain, no gain" epithet.
Isometrics. Muller showed that one isometric contraction (slightly more for the well-trained athlete) of 40%-60% of maximum held for a few seconds each day would result in the maximum possible increase of muscle strength. From this study, while slightly modified, renewed interest in the Charles Atlas type of "dynamic tension" exercises, in addition to aerobic isotonic exercises, has become widespread within the sports world.
A distinct advantage of isometric exercise is to early prevent or retard atrophy resulting from necessary immobilization (eg, fracture, whiplash). A disadvantage of purely isometric exercises is that benefits are confined to a range of motion of only 20 to either side of the training angle at which contraction is performed.
Structured Exercise Regimens
There are many types of exercise and each has its particular goal therapeutically. See Table 1.
Table 1. Basic Muscle Function, Dysfunction, & Rehabilitative Therapy
Function Dysfunction Rehabilitation Strength Weakness Exercises against resistance Physiologic elasticity Spasticity Relaxing exercises, autosuggestion, biofeedback, postural correction
Spasm Pain relief, "gate" blocking, relaxation exercises, hypnotherapy
Tension Relaxing exercises, psychotherapy, hypnotherapy, hydrotherapy, meridian therapy Physical elasticity Contracture Stretching exercises, joint mobilization Coordination
Incoordination Strengthening and relaxation exercises, coordination training, biofeedback. Regardless of the type of exercises and regimens used, careful consideration must be made of the total situation of the particular labor or competition involved. There is always the question in athletics of how much training is enough, as overtraining can dull an otherwise sharpened performance.
Passive Exercise
Passive exercise consists of stretching and moving a joint through its various ROMs by an external force. It is unvolitional as far as the subject is concerned; ie, it manipulates local tissues without input from the high CNS centers. It is highly valuable initially in cases of paralysis or severe weakens. Because it sets up sensory bombardment to the spinal cord if the afferent neurons are intact (and hopefully to the long ascending tracts), it is helpful in attempting to re-establish an impaired neuromuscular circuit. Mechanoreceptor stimulation also appears to have an enhancing effect on connective-tissue healing, which may be related to the fact that exercise is the best preventive for osteoporosis.
Passive exercise may be applied manually or mechanically, and theoretically the affect should be the same. Nevertheless, there is much we can only speculate about the benefits and mechanisms of "therapeutic touch" from human to human. Two types of passive exercise can be used, unforced or forced, depending n the circumstances and goal involved. Harrelson and scores of others recommend painless unforced exercise to maintain joint mobility. Forced, possibly uncomfortable, passive exercise is used to nudge motion beyond the range of abnormally restricted motion.
Muscle Training by Resistance Exercise Equipment
A goal in weight training for physical conditioning or rehabilitation is to work the muscle at maximum efficiency throughout the joint's range of movement. This goal, reported Ariel and associates, necessitates proper assignment of force, displacement, velocity, and when desired, time, acceleration, and the amount of work and power. To do this, it is necessary to assess the individual's biomechanical changes and then to develop a resistance and velocity intensity that will accommodate those changes in a functional manner. This means that the variations in resistance intensity and velocity must be precisely and wisely incorporated into a resistive mechanism. It is also essential that the operation of such a mechanism is not adversely affected by improper machine design.
The benefits of exercise machines have not met their publicity. A principle of biomechanics states that inertial forces affect the motion and magnitude of the muscle movement. The smaller the inertial forces produced by the exercise machine's moving parts, the greater the muscular involvement. Most all gravity-dependent exercise machines are subject to inertial forces and apply resistance in one direction only. Thus, only the agonist muscle group is exercised and the training is not automatically followed by a correspondingly balanced antagonist muscle activity.
Exercise equipment using springs, torsion bars, etc, is able to overcome the inertia problem to some extent and can partially overcome the unidirectional force restriction. However, the problems of safety, nonlinear resistance, and the nonadaptability of the machine to an individual's force characteristics are still serious drawbacks. For this reason, most authorities consider them unacceptable.
One type of machine in common use operates on a constant velocity principle where the resistance is changed in direct relationship to the forces acting on the moving bar. This equipment, however, operates on an open loop mechanism that does not allow feedback control of the exercise while it is in progress and the velocities cannot be changed in a manner that simulates ballistic human motion.
Hydraulic mechanisms can overcome the inertial problem as well as the unidirectional problem. However, applications of such a mechanism are limited by a fixed flow rate that restricts the user to move at a limited number of preset velocities and, at any given moment, the user is unsure of just what his performing force or velocity actually is.
A computerized closed-loop feedback control exercise mechanism has been developed that can overcome these problems and provide the user with the flexibility and the adaptability to exercise at any resistance or velocity pattern throughout the range of movement. Such sophisticated equipment is often impractical within the typical family-oriented practice but it serves well in the orthopedic and sports-injury related practice. Far less sophisticated means can be used in most instances.
Home Exercise Prescriptions
Because time and convenience is limited, treatment cannot be restricted to the office environment. Nutritional counsel and prescribed home exercises, for example, are extremely beneficial in both musculoskeletal and many visceral disorders. To be effective in enhancing a patient's rehabilitation, exercise must obviously be conducted with sufficient warm-up, frequency, duration, and intensity, and these factors must be based on the individual patient's current functional and biomechanical status. Thus, explicit, motivational instruction and patient compliance are often basic factors in arriving at a successful outcome.
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