A rejoinder to "Exercise Programs for Patients with Post-Polio Syndrome: A Case Report" - a short communication.

A Rejoinder to "Exercise Programs for Patients with Post-Polio Syndrome: A Case Report"--A Short Communication

This communication is in response to the article by Michael T Gross and Charles P Schuch entitled "Exercise Programs for Patients with Post-Polio Syndrome: A Case Report" published in the January 1989 issue of Physical Therapy. The investigators examined the effects of a rigorous isokinetic training program on peak torque of the knee flexor and extensor muscles of a post-polio patient. The literature on post-polio syndrome, however, does not support the use of either conventional muscle strengthening regimens or rigorous isokinetic exercise programs in the management of post-polio syndrome. In addition, based on the observation that there was no appreciable increase in muscle strength in either the affected or the apparently unaffected leg, the investigators concluded that their rigorous exercise program was not deleterious. The lack of a normal training response, however, is consistent with bilateral muscle fatigue secondary to overuse rather than muscle weakness secondary to disuse. This result is consistent with the need for a balance between rest and low-intensity exercise, which will help to maintain or enhance function while slowing rather than hastening further deterioration. We hope that this rejoinder clarifies some of the misconceptions that may arise from the Gross and Schuch article and that physical therapists consider very carefully the rationale for any type of exercise program for post-polio patients. [Dean E, Ross J, MacIntyre D: A rejoinder to "Exercise Programs for Patients with Post-Polio Syndrome: A Case Report"--A short communication. Phys Ther 69:695-699, 1989] Key Words: Exercise, strengthening; Lower extremity, general; Muscle performance, measurement; Poliomyelitis, general. This short communication is a rejoinder to an article entitled "Exercise Programs for Patients with Post-Polio Syndrome: A Case Report" by Michael T Gross and Charles P Schuch that appeared recently in Physical Therapy.[1] Gross and Schuch undertook this case study using a single-subject design in which peak torque for the knee flexor and extensor muscles of both legs of a patient with post-polio syndrome was assessed before, during (at 2, 4, and 6 weeks), and after (at 6 and 22 weeks) "rigorous isokinetic training."[1] They defined the "affected leg" as the patient's left leg and the "unaffected leg" as his right leg. The literature to date on post-polio syndrome, however, fails to support the underlying rationale of their study with respect to the application of rigorous isokinetic exercise in this patient population. Nor, in our view, can the authors' conclusion that their intensive exercise program had no deleterious effect on the patient with post-polio syndrome be supported. We have grave concern that clinicians may adopt the authors' conclusions and implement aggressive isokinetic exercise programs for patients with post-polio syndrome without an understanding of the literature to date. Gross and Schuch state, "The purpose of this case report is to report the result of a specific isokinetic exercise regimen performed by a patient with post-polio syndrome."[1](p73) Part of the authors' rationale for conducting their study was that "no information is available regarding the effects of an intensive program of exercise for patients with post-polio syndrome."[1](p73) The literature cited by Gross and Schuch, however, included the work of Alsentzer[2] and Twist and Ma.[3] Citing the work of Alsentzer, they stated, "`Strengthening exercises add only short-lived, if any, strength and endurance' in patients with post-polio syndrome and may accelerate the development of weakness and loss of endurance."[1](p72) Furthermore, citing the work of Twist and Ma, they stated, "`Tough and exhaustive exercise' is inappropriate for those individuals experiencing a decline in muscle strength and endurance secondary to post-polio syndrome."[1](p72) We propose that these two articles generally reflect the current literature on exercise for post-polio patients[4-6] and that no evidence exists, to our knowledge, to support the rationale of Gross and Schuch in undertaking an "aggressive isokinetic exercise program" for a post-polio patient. One apparent exception to a conservative approach to the management of post-polio patients is the work of Einarsson and Grimby.[7] Although these investigators reported short-term increases in strength in the affected quadriceps femoris muscles of 12 patients with a history of poliomyelitis, they cautioned against widespread implementation of rigorous muscle strengthening programs until both the short- and long-term effects have been studied further. In a discussion of Einarsson and Grimby's work, Wiechers argued that although muscle strength can be improved in patients with poliomyelitis, this improved strength could be at the expense of long-term function.[7] Although the role of exercise in the management of post-polio syndrome has been controversial, nonexhaustive exercise is generally believed to be preferable.[4-6] In addition, rest is now believed to be a significant consideration; however, the negative consequences of inactivity have been well documented[8-10] and may be devastating to the individual debilitated by poliomyelitis. Nonfatiguing resistive muscle training as described by Feldman constitutes one therapeutic approach.[4] Another alternative, however, is a modified program of general body conditioning in post-polio patients.[5,11] General body conditioning has the advantage of maintaining or improving strength needed for functional activities while enhancing the efficiency of muscle contraction and minimizing strain. Specifically, endurance, coordination, and overall mechanical efficiency can be improved with general body exercise,[12] whereas resistive muscle training leads to highly specific metabolic and mechanical demands on the muscle undergoing training, resulting in highly specific effects.[13,14] Thus, given that optimal management of post-polio syndrome probably consists of a balance between not too much and not too little exercise based on the patient's subjective reports of fatigue and discomfort, a modified program of general conditioning could have some role. The role of exercise for the post-polio patient has been controversial for several reasons. Bennett and Knowlton, over 30 years ago, reported the deleterious effects of overwork on partially denervated skeletal muscle.[15,16] Partially denervated muscle, which in poliomyelitis primarily reflects viral damage to the anterior horn cells, does not have the physiologic capacity to respond to a conventional muscle strengthening regimen. Partially denervated skeletal muscle, therefore, certainly would not have the physiologic capability to respond to the exercise program chosen by Gross and Schuch for their post-polio patient, which they describe as "more intensive" than the exercise programs reported by Lesmes et al[17] and Krotkiewski et al.[18] Resistive muscle training for the unaffected muscles as well as the affected muscles may also be contraindicated. This contraindication is based on the fact that the unaffected muscles of post-polio patients often work harder than the muscles of healthy individuals to compensate for the weakness of affected muscles and limbs.[6] These muscles, similar to the more severely affected muscles, may also succumb to fatigue rather than muscle weakness. The distinction between weakened and fatigued muscle is a crucial one in relation to any discussion of post-polio syndrome and is addressed later in the context of our interpretation of the findings of Gross and Schuch. Finally, apparently unaffected muscles have been reported to develop late onset signs and symptoms of previous poliomyelitis involvement.[19,20] Thus, based on the current literature, the rationale of Gross and Schuch cannot be supported to justify performing their study. To summarize the findings of Gross and Schuch, they concluded that "the results of this case study do not support the conclusions"[1](p75) of Alsentzer[2] or Twist and Ma.[3] They further concluded, "Our patient did not demonstrate an appreciable decrease in the ability to exert torques either at the end of the vigorous 6-week exercise program or at 6 or 22 weeks following the cessation of the exercise program. Our patient, however, did not demonstrate what we consider an appreciable increase in the strength of muscles affected or unaffected by poliomyelitis. Twist and Ma did report a rather dramatic increase in the strength of a debilitated patient with post-polio syndrome following a more conservative exercise program....The results of our study indicated no deleterious effects from an intensive exercise program with a relatively active patient."[1](p75) Several observations can be made with respect to the authors' conclusions. They describe the patient's left leg as the affected leg and the right leg as the unaffected leg. That the right leg is unaffected is not supported by the data for two reasons. The first reason is that Normal muscle strength assessed isokinetically reflects the well-established relationship between flexor and extensor muscle strength for different speeds of contraction, specifically the flexion-to-extension ratio. This ratio for the lower extremity has been reported to range between 60% and 70% for contractions performed at 60 [degrees]/sec[21-24] and 79% at a contraction speed of 180 [degrees]/sec.[22] The ratio tends to increase from that observed at 60 [degrees]/sec with increased contraction speed.[23-25] This relationship appeared to hold true in Gross and Schuch's case study for contractions of the unaffected right leg at 60 [degrees]/sec, but at 180 [degrees]/sec flexor muscle strength was initially in excess of extensor muscle strength. No mention was made by the authors about the discrepancy in torque observed at the two contraction speeds and its implications regarding the "normalcy" of the right leg. The second reason the data do not support the right leg as the unaffected leg is that the authors made a point of acknowledging that the program undertaken by their patient was "relatively more intensive" than that used to effect muscle strength changes in healthy subjects. A characteristic feature of weak musculature is that it responds to a training stimulus. Lack of a training response, however, is consistent with the muscle being fatigued. Neither the affected leg nor the unaffected leg was observed to show any significant training effect, with the possible exception of extension on the right side at a contraction speed of 180 [degrees]/sec. This apparent improvement in the right knee extensor muscles at 6 and 22 weeks posttest, however, seems incongruous with no change observed at the end of training (ie, 6 weeks after beginning the program). Although Gross and Schuch offer no explanation for these findings, three conclusions can be drawn. First, the findings are consistent with muscle fatigue secondary to overuse rather than weakness secondary to disuse in both of the patient's legs. Second, given this muscle fatigue, a resistive exercise program--particularly one that is "relatively more intensive" than that advocated for healthy persons--is not supported. Third, muscles whose responses are compromised secondary to fatigue need judiciously prescribed rest rather than exercise to prevent further deterioration of function. Thus, the conclusion drawn by Gross and Schuch that "the results of our study indicated no deleterious effects from an intensive exercise program with a relatively active patient"[1](p76) cannot be supported on the basis of their data. The institution of a rigorous resistive muscle training program for post-polio patients can be countered for several reasons, in addition to the fact that these muscles do not have the same physiologic capacity to respond to such training. Postural malalignment, for example, contributes to excessive biomechanical strain. Thus, the muscles and joints of both affected and unaffected limbs are not afforded the same degree of either muscular or ligamentous protection as those of individuals without a history of poliomyelitis. The risk of traumatizing the muscles and joints of the limbs of patients with poliomyelitis and thus contributing to further debility also is significant. This possibility is supported by the increasing evidence that with the passage of time, particularly about 30 years after initial onset, post-polio patients have overexerted and overstrained nonaffected as well as affected muscles and limbs as a means of compensating and maintaining their function. This pattern, in turn, may contribute to chronic muscle fatigue, increased muscle and joint pain, increased instability, complaints of knees and ankles giving out, and an increased incidence of falling. Rigorous resistive muscle training in post-polio patients could further perpetuate this cycle and thereby exacerbate these symptoms. In summary, the literature suggests that not all post-polio patients are candidates for therapeutic exercise. One primary objective of investigators in the field is to be able to identify those patients who will benefit from prescribed exercise and, if some form of exercise is not contraindicated, to determine the principles that should be used to guide clinicians in prescribing exercise optimally. New approaches such as modified body conditioning may help to overcome some of the limitations of resistive muscle training and address cardiorespiratory deconditioning in post-polio patients. Considerable research is needed, however, to optimize exercise prescription for patients with post-polio syndrome. We hope that this rejoinder has clarified some of the misconceptions that may arise from the article by Gross and Schuch and that clinicians consider very carefully the rationale for any type of exercise program before prescribing that program for their post-polio patients.

References [1]Gross MT, Schuch CP: Exercise programs for patients with post-polio syndrome: A case report. Phys Ther 69:72-76, 1989 [2]Alsentzer J: Post-polio syndrome. NC Med J 47:399-400, 1986 [3]Twist DJ, Ma DM: Physical therapy management of the patient with post-polio syndrome: A case report. Phys Ther 66:1403-1406, 1986 [4]Feldman RM: Use of strengthening exercises in post-polio sequelae: Methods and results. Orthopedics 8:889-890, 1985 [5]Owen RR, Jones D: Polio residuals clinic: Conditioning exercise program. Orthopedics 8:882-888, 1985 [6]Perry J, Fleming C: Polio: Long-term problems. Orthopedics 8:877-881, 1985 [7]Einarsson G, Grimby G: Strengthening exercise program post-polio subjects. In Halstead LS, Wiechers DO (eds): Research and Clinical Aspects of the Late Effects of Poliomyelitis. New York, NY, March of Dimes Birth Defects Foundation, 1987, pp 275-283 [8]Saltin B, Blomqvist G, Mitchell JH, et al: A longitudinal study of adaptive changes in oxygen transport and body composition. Circulation 38(Suppl 5):1-78, 1968 [9]Chobanian AV, Lille RD, Tercyak A: The metabolic and hemodynamic effects of prolonged bed rest in normal subjects. Circulation 49:551-556, 1974 [10]Hahn Winslow E: Cardiovascular consequences of bed rest. Heart Lung 14:236-246, 1985 [11]Dean E, Ross J: Modified aerobic walking program: Effect on patients with postpolio syndrome symptoms. Arch Phys Med Rehabil 69:1033-1038, 1988 [12]Shephard RJ: Physiology and Biochemistry of Exercise. New York, NY, Praeger Publishers, pp 88-94, 1985 [13]Bilowet DS: Specificity versus transfer of training and its implications for rehabilitation. Am Corr Ther J 22:139-144, 1968 [14]Gonyea WJ, Sale D: Physiology of weightlifting exercise. Arch Phys Med Rehabil 63:235-237, 1982 [15]Bennett RL, Knowlton GC: Overwork weakness in partially denervated skeletal muscle. Clin Orthop 12:22-29, 1958 [16]Knowlton GC, Bennett RL: Overwork. Arch Phys Med Rehabil 38:18-20, 1957 [17]Lesmes GR, Costill DL, Coyle EF, et al: Muscle strength and power changes during maximal isokinetic training. Med Sci Sports 10:266-269, 1978 [18]Krotkiewski M, Aniansson A, Grimby G, et al: The effect of unilateral isokinetic strength training on local adipose and muscle tissue morphology, thickness and enzymes. Eur J Appl Physiol 42:271-281, 1979 [19]Frustace SJ: Poliomyelitis: Late and unusual sequelae. Am J Phys Med Rehabil 66:328-337, 1988 [20]Hayward M, Seaton D: Late sequelae of paralytic poliomyelitis: A clinical and electromyographic study. J Neurol Neurosurg Psychiatry 42:117-122, 1979 [21]Moffroid M, Whipple R, Hofkosh J, et al: A study of isokinetic exercise. Phys Ther 49:735-747, 1969 [22]Wyatt MP, Edwards AM: Comparison of quadriceps and hamstring values during isokinetic exercise. Journal of Orthopaedic and Sports Physical Therapy 3:48-56, 1981 [23]Thomas LE: Isokinetic torque levels for adult females: Effects of age and body size. Journal of Orthopaedic and Sports Physical Therapy 6:21-24, 1984 [24]Chung F: Effect of two input adapters used with the Orthotron II on knee torque. Physiotherapy Canada 40:356-360, 1988 [25]Nosse LJ: Assessment of selected reports on the strength relationship of the knee musculature. Journal of Orthopaedic and Sports Physical Therapy 4:78-84, 1982

E Dean, PhD, is Assistant Professor, School of Rehabilitation Medicine, University of British Columbia, 2211 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 2B5. Address correspondence to Dr Dean. J Ross, BSR, MSc, is Clinical Faculty Member, School of Rehabilitation Medicine, University of British Columbia, and Physical Therapist, Vancouver General Hospital, 855 W 12th Ave, Vancouver, British Columbia, Canada V5Z 1M9. D MacIntyre, BSR, MPE, is Head and Instructor II, School of Rehabilitation Medicine, University of British Columbia.