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1982; 62:1754-1756.PHYS THER.Steven J Rose and Jules M RothsteinPerspectiveMuscle Biology and Physical Therapy : A Historical

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Mu s c l e B io l o g y a n d P h y s i c al T h e r a p yA His to r i ca l Persp ect iveSTEVEN J. ROSEand JULES M. ROTHSTEIN

K ey W o r d s : Muscle biology, Physical therapy.A historical review of treatment strategies used by

physical therapists reveals that initially therapists emphasized corrective exercise1, 2 and reeducation ofmuscles for the return of function.3 Muscle wasequally emphasized in treating a variety of patients,for example, those with war injuries, polio, postureproblems, and C NS lesions. The pioneers in physicaltherapy focused primarily on muscle, using theirknowledge of gross and functional anatomy and, toa lesser extent, what was known about muscle physiology. The first physical therapists used palpationand manual muscle testing to evaluate m uscle.2,4 "6 Asthe profession matured, therapists began to examine the action of muscles in terms of axes and vectors.2, 7-9 Combining their knowledge of mechanicswith their knowledge of gross anatomy, therapistswere then able to perform basic kinesiological analyses by examining the line of pull of various musclesthroughout an arc of m ovement.

Knowledge of muscle physiology in the early daysof physical therapy consisted of length-tension diagrams and the classic works of Du chenn e10 and Stein-dler.11 Despite this paucity of knowledge, therapistsempirically described physiological phenomena, suchas stretch-weakness,6 fatigue,2, 12 and exercise hypertrophy.2, 12 All of this empirical knowledge was usedin what were then the primary treatments of dysfunction, namely, muscle reeducation and corrective exercise. These treatments were developed when littlewas known about muscle and were based on theobservations of keen observers. Therapists knew,based on color differences, that there were differentkinds of muscle and that force was related to musclesize and to the speed of contraction.12 However, neither the heterogeneity of muscles nor the force-velocity relationship was understood well enou gh to makethese observations clinically useful.

N e u r o p h y s i o l o g i c a l a n d A r t h r o k i n e m a t i cA p p r o a c h e s

Two major treatment philosophies have dominatedphysical therapy during the last two decades: the

neurophysiological approaches for patients with CNSdysfunction 13 and the arthrokinematic approaches forpatients with orthopedic problems.Each of these philosophies focused on nonmuscularelements to explain dysfunction. In one case, thenervous system was thought to be the element most

affected by treatment. In the other case, joint structures were viewed as the site where pathologicalproblems were located and could be treated. Musclewas rarely considered as being contributory to painor disability and was not emphasized in treatment.As the physiology of peripheral receptor mechanisms became widely appreciated in the late fifties,treatment rationales were developed based on interpretations of the neurophysiological literature. Withthis shift, concepts such as facilitation and inhibitiondominated the theoretical approaches to patient care.Interpretations of Sherringtonian physiology focusedtherapists on control mechanisms rather than on themuscle itself. Concurrent with this shift, patients withneurological problems, especially stroke victims, became one of the main patient groups treated bytherapists. This change in population from patientswith polio to patients with CNS dysfunction made ashift in emphasis from the muscle to the nervoussystem seem logical.The consensus that joint dysfunction was a majorcause of disability and pain led to the widespreadadoption of manual therapy techniques in the sev

enties. Just as neurophysiological approaches seemedlogical for patients with CNS dysfunction, orthopedictechniques seemed logical for patients with arthrokinematic dysfunction. The focus in orthopedic therapywas on joint structure and its innervation. The arthrokinematic orientation essentially discounted therole of muscle in disability and pain.G r o w i n g K n o w l e d g e o f M u s c l e P h y s i o l o g ya n d P l a s t i c i t y

At the same time that dysfunction was being explained in nonmuscular terms by these two philosophies, biologists were demonstrating that muscle wasamon g the most plastic tissues in the body . This new ly1754 PHYSICAL THERAPY

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described plasticity implicated muscle in every typeof movement dysfunction associated with both neurological and orthopedic origins.The finding that muscle is mutable would haveextremely important implications for physical therapists, especially because this mutability was demonstrated using the very modalities found in almostevery clinic. Muscle biologists have studied muscle

mutability using exercise regimens, electrical stimulation, and cast immo bilization. Paradigms that simulated patient problems (eg, immobilization, denervation, and CNS lesions) were also shown to lead tosignificant cellular and performance changes in muscle.

Muscle biologists have demonstrated that muscle ismutable and responds to both normal and pathological stimuli. Whe n m uscle responds to normal stimuli,it can become exquisitely sp ecialized to the functionaldemands placed upon it. When muscle responds topathological stimuli, it may lose some of that functional specialization and fail to perform adequately.The knowledge that muscle is specialized and mutablehas vast practical significance. We can gain someinsight into how muscle biology may be used byexamining how it is applied by others.

Applied physiologists have been using the knowledge and techniques of muscle biology to describenormal hum an performance. Th ese clinical scientistshave begun to examine the relationships betweenmuscle chan ges and athletic performance, cardiovascular endurance, strength, and aging. Their researchhas examined the relationship of muscle compositionto genetic factors and gender. Althou gh applied physiology is a relatively new field, it is widely respectedin the scientific community because its practitionershave used the knowledge and techniques of musclebiologists for the analysis and improvement of h umanperformance.

In the hands of the physical therapist, who istrained in kinesiology and who works daily withmovement dysfunction, knowledge of muscle biologycould also become a potent tool. Understanding thecellular basis for dysfunction allows the therapists tobe more effective in evaluation and treatment. Andknowledge of the cellular effects of treatment allowsus to understand the physiological effects of ourintervention. Through the knowledge of what anexercise can and cannot do , we can better respond tothe patient's individual needs. Consider the strength-trained patient who reports difficulty after severalhours of wa lking or standing. We know that strengthtraining (the use of heavy resistance) leads to increased muscle mass and increased tension capacitybut has little effect on fatigue resistance. Therefore,this patient needs low-resistance exercise that willincrease the aerobic capacity of the cell and improvefatigue resistance.

By identifying the nature of the patients' deficitsthe type II fiber atrophy of the steroid patient, thetype II fiber atrophy of the cancer patient, and thelength-associated chang es of the stretch-weakness patienttherapists can be better prepared to treat specific problems. By understanding that cast immobilization leads to atrophy of the type I and type II fibers,therapists can be better prepared to treat patients w ithorthopedic problems. Know ledge o f the specializationand mutability of muscle allows us potentially tocause changes to take place that will have specificfunctional benefits or to prevent changes that aredeleterious.

We have apparently come full circle. The firsttherapists appreciated the role of m uscle even thoughthey practiced at a time when little was understoodabout muscle phy siology or muscle plasticity. In viewof the limited knowledge that these therapists hadavailable to them, it is to their credit that throughclinical observation and dedication they developed aremarkable appreciation of the importance o f m uscle.Our predecessors looked at patients by carefully examining muscle function and then developed treatment programs based on the results. The effectivenessof their treatments provided the justification for theexistence of our profession. If our predecessors withso little formal scientific knowledge could do so verymuch, let us imagine what we in the years ahead cando.

Clearly, applying our knowledge of muscle biologycould provide us with one of the most significantmeans of establishing scientifically based practice. Inevery patient we treat, changes in muscle are likely tooccur. Therefore, the appreciation of muscle mutability should be incorporated in the approach to allpatients whether they have neu rological, orthopedic,or other medical conditions. Therapists have diverseapproaches to patient care. Some approaches arebased on arthrokinematic considerations, whereasothers focus on neurophysiological considerations.Practitioners need to consider the effects of stimuli onmuscle induced by the pathological condition or bythe treatment. Patient care may be improved whenclinicians integrate this knowledge with any othertreatment focus, whether arthrokinematic or neurophysiological.

Knowledge of muscle biology applied by practitioners in any areas of phy sical therapy can only serveto increase the effectiveness of treatment. However,of perhaps greater importance is the possibility thatthrough the use of information gained from musclebiology entirely new approaches to patient care maybe generated. We now can contemplate the development of new treatment strategies that focus on musclethe biological element therapists have workedwith since the inception of the profession.

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REFERENCES1 . Kru se n FH: P h ys i ca l M e d i c i n e . P h i l a d e l p h i a , P A, WB Sa u n d e r s C o , 1 9 4 1 , p p 4 0 - 4 12 . Ewerhardt FH, Ridd le GF: Therapeut i c Exerc ise . Ph i lade l ph ia , PA, Lea & Febiger , 1947, pp 9-1 13 . B e n n e t t RL: M u sc l e r e e d u c a t io n : A b r ie f d i scu ss i o n o f so meo f t h e ba s i c p r i n c i p l e s . P h ys i o t h e ra p y Re v 2 7 : 2 43- 2 46 ,1 9 4 74 . B e n n e t t RL : M u sc l e t es t i n g : A d iscu ss i o n o f t h e i mp o r t an ceo f a ccu ra t e mu sc l e te s t i n g . P h ys i o th e ra p y Re v 2 7 : 2 42 , 1 9475. Dan ie ls L, Wi l li ams M, Worth ing ham C: Mus c le Test ing: Te ch n i qu es o f M a n u a l Ex ami n a t io n . P h i l ad e l p h i a , P A, WB Sa u n d e rs Co , 1 9466 . Ke n d a l l O , Ke n d a l l FP : M u sc l e T e s ti n g a n d Fu n c t i o n . B a l t i mo re, MD, The Wi ll i ams & Wi lk ins Co , 1 949

7. Wi l li ams M, Worth ingh am C: Therap eut i c Exerc ise fo r BodyAl ignment and Func t ion . Ph i lade lph ia , PA, WB Saund ers Co,1 9578. B runnst rom S: Cl in i ca l K ines io logy . Ph i lade lph ia , PA, FADavis Co, 1 9629. Wi l l i ams M, Lessner HR: B iomechan ics o f Human Mot ion .Ph i lade lph ia , PA, WB Saunders Co, 19621 0. Du ch e n n e GB : P h ys i o l o g y o f M o t i o n , Ka p l a n EB ( t r a n s ) .Ph i lade lph ia , PA, JB L ipp incot t Co, 19491 1 . Steind ler A: K ines io logy o f the Human Bo dy. Spr ing f ie ld , IL ,Char les C Thomas, Publ i sher , 19551 2 . Wakim K: The s ke le ta l muscu la ture in hea l th and d iseas e . InKrusen FH (ed) : Phys ica l Med ic ine an d Rehabi l i ta t ion fo r theCl in i c ian . Ph i lade lph ia , PA, WB Saund ers Co , 1 9 5 1 , p p 2 8 4 -31 21 3. An e x p l o ra to r y a n d a n a l y t i ca l su rv ey o f t h e ra p e u t ic e x e rc i se .A m J P h y s M e d 4 6 : 1 - 1 1 9 1 , 1 967

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1982; 62:1754-1756.PHYS THER.Steven J Rose and Jules M RothsteinPerspectiveMuscle Biology and Physical Therapy : A Historical

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