1984; 64:653-657.PHYS THER. Gale M Gehlsen, Susan A Grigsby and Donald M WinantMultiple SclerosisMuscular Strength and Endurance of Patients with Effects of an Aquatic Fitness Program on the

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Effects of an Aquatic Fitness Program on the Muscular Strength and Endurance of Patients with Multiple Sclerosis

GALE M. GEHLSEN, SUSAN A. GRIGSBY, and DONALD M. WINANT

This study quantified the effects of an aquatic exercise program on muscular strength, endurance, work, and power of patients with multiple sclerosis. Ten individuals with a mean age of 40 years participated in a 10-week aquatic exercise program. Two types of isokinetic dynamometers were used to assess the mus­cular variables studied. A Cybex® II dynamometer was used to measure peak torque, work, and fatigue in the knee flexor and extensor muscles and a biokinetic swim bench was used to measure muscular force, work, fatigue, and power in the upper extremities. Five velocity settings were selected for each of three testing trials (pretrial, midtrial, and posttrial). For the lower extremities, analysis of variance indicated a significant improvement of peak torque for knee extensor muscles from the pretrial to midtrial (p < .05). Peak torque values from pretrial to midtrial for knee flexors and from midtrial to posttrial for both the knee extensor and flexor muscles indicated a nonsignificant difference at each velocity studied. Fatigue and work values in the lower extremities improved significantly between the pretrial and posttrial (p < .05). For the upper extremities, an analysis of variance indicated a significant increase in all force measurements from pretrial to posttrial (p < .05). Power and total work values also improved significantly (p < .05). No significant difference in fatigue measurements for the upper extremities was found. The results of this investigation indicated that an aquatic exercise program may induce positive changes in muscular strength, fatigue, work, and power in patients with multiple sclerosis.

Key Words: Exercise therapy, Multiple sclerosis, Physical therapy, Water.

Multiple sclerosis (MS) is a degenerative neurological dis­order characterized by the demyelinization of CNS pathways that may, in part, be responsible for the neuromuscular dys­function found in persons with the disease. The primary focus of research in this area has been on determining the etiology of the disease and development of a cure rather than on trying to improve the general fitness of the patient. Because the etiological origin of MS has yet to be determined, treatment has been limited to the control of symptomatic complications, such as muscular fatigue, weakness, contracture, and spastic­ity, through physical therapy and the use of drugs.1-3

Exercise programs directed toward treating certain specific deficits have been viewed by some as having the most to offer patients with MS.4 Traditionally, such techniques as active and passive range of motion, coordination exercises, and various facilitation techniques to induce voluntary motor activity or inhibit unwanted motor patterns have been used

to help alleviate or modify neuromuscular complications, such as ataxia, spasticity, contracture, and disuse atrophy of the skeletal muscles.5 A more recent trend has favored the use of dynamic exercise (calisthenics, cycling, and swimming) for sustaining the physical conditioning response and preventing neuromuscular complications associated with physical inac­tivity.5, 6 Russell has implied that dynamic exercise creates a hyperaemic response in the body that results in opening up circulation to the ischemic regions of the spinal cord and brain.6 He observed that a rest-exercise program for patients with MS arrested the pathogenic process by preventing the fulminating or malignant type or both from developing.

Certain physical activities, such as jogging, may be inappro­priate for patients with MS because of exposure to harsh environmental conditions and the requirement for stamina and balance beyond the patients' capacities. The buoyant nature of water and the ability to control water temperature effectively, however, are characteristics that have made a positive therapeutic response in patients with neuromuscular disease possible.7

No empirical evidence is available on the benefits of an aquatic exercise program for the patient with MS. The phys­ical therapist, therefore, is unable to make any recommenda­tion (positive or negative) concerning aquatic exercise pro­grams for patients with MS. The purpose of this study was to determine the effects of an aquatic exercise program on the

Dr. Gehlsen is Professor of Physical Education and Director of the Biome­chanics Laboratory, Ball State University, Muncie, IN 47306 (USA).

Ms. Grigsby is Assistant Professor, Physical Therapy Program, Department of Physiology and Health Science, Ball State University, Muncie, IN.

Mr. Winant was a graduate student in the Department of Men's Physical Education, Ball State University, when this study was conducted. He is currently a Research Assistant, Department of Rehabilitative Medicine, University Hos­pital, University of Washington, Seattle, WA 98105.

This article was submitted March 14, 1983; was with the authors for revision 18 weeks; and was accepted December 20, 1983.

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TABLE 1 Demographic Data of Subjects with Multiple Sclerosis

Subject No.

1 2 3 4 5 6 7 8 9

10

Age (yr)

30 54 61 23 51 37 36 35 37 38

Sex

Woman Woman Woman Woman Woman Woman Man Man Man Man

Height (M)

1.80 1.68 1.59 1.68 1.68 1.62 1.87 1.76 1.82 1.83

Pretrial 59.0 57.2 59.1 62.2 79.8 54.0 77.6 69.3 74.0 78.0

Weight (kg)

Midtrial 58.0 55.9 57.8 59.7 79.4 53.8 76.2 71.5 73.4 74.8

Posttrial 59.8 56.0 60.0 60.8 79.3 54.0 75.0 70.1 73.7 73.4

upper and lower extremity muscular force, torque, fatigue, work, and power in patients with MS. The study attempted to quantify the effects of the aquatic program on muscular strength and endurance of individuals with MS to determine whether this type of exercise program could be effectively used by the clinician to improve overall patient conditioning.

METHOD

Subjects A total of 13 subjects comprised the initial experimental

group, but 3 subjects dropped out of the study before the fifth week of testing. We collected data on 10 subjects with MS (six women and four men) with a mean age of 40.2 years. The subjects were recruited from the local Multiple Sclerosis Association Chapter. We based eligibility on clinical assess­ment of disease status by attending physicians. Selection criteria required that all subjects be ambulatory and the disease be in a remissive state. We obtained informed consent as a prerequisite for participating in the laboratory tests and exercise program. Table 1 lists demographic data.

Experimental Design We scheduled three testing trials of the upper and lower

extremities' muscular torque, force, fatigue, work, and power for each of the 10 subjects on two types of isokinetic dyna­mometers. The pretrial tests were administered the week before the start of a 10-week aquatic exercise program; the midtrial tests were conducted during the fifth week of the aquatic exercise program; and the posttrial tests were admin­istered during the week following the completion of the aquatic exercise program.

Equipment We used a Cybex®* II isokinetic dynamometer to measure

knee joint flexor and extensor muscle peak torque at angular velocities of 60, 120, 180, 240, and 300°/sec. A digital work integrator (a component of the Cybex® II) was used to deter­mine total work.

A biokinetic swim bench† measured peak force, total work, and maximal power at varying upper extremity velocities.

The apparatus was a semiaccommodating resistance device that could be preset at a regulated speed to provide a constant amount of velocity in proportion to the force applied by the user. The speed setting(s) were S-0 (0.9 m/sec), S-2 (1.24 m/ sec), S-4 (1.7 m/sec), S-6 (2.2 m/sec), and S-8 (2.72 m/sec). The swim bench was designed with a padded incline for a prone position and with pull paddles for the hands of the subjects. Each paddle connected to an attached isokinetic resistance device by one rope that ran over a pulley and around the geared spool inside. A governor built onto the spool regulated the rate at which each rope released from the spool. The force generated during each arm pull was deter­mined from a physiograph chart recorder; muscular work was measured with the digital work integrator (a component of the swim bench); time was measured by the length of the force curve; and muscular power was calculated by dividing work by the time of the pull.

Test Protocol Lower extremities. Before each testing session, the dyna­

mometer, chart recorder, angle channel, and digital work integrator were calibrated. The subjects underwent a five-minute warm-up period consisting of two contractions at the designated angular velocities. We minimized extraneous body movement by restraining each subject with shoulder har­nesses, a hip belt, a midthigh restraint strap, and an ankle strap. The level-arm length and the number of back support pads remained constant for each subject; we positioned the midpoint of the lever-arm crank next to the lateral femoral condyle of the knee joint. The testing protocol required that each subject continue at each preset angular velocity until peak torque decline was observed. We conducted retests at specified angular velocities to verify peak torque values. After dynamic torque measurements were obtained, the isometric (0°/sec) torque of the knee extensor and flexor muscles was taken at a leg angle of 45 degrees. We gave the subjects five minutes of rest before total work data were obtained from a test of 50 (extension) contractions at the preset speed of 180°/ sec. Muscular fatigue values were calculated from the total work data. We considered fatigue values to be the percentage of peak torque decline (the percentage of difference between the first and final peak torque values) as described by Thor-stensson.8

Upper extremities. We familiarized all subjects with the use of the biokinetic swim bench and allowed them a warm-up of two practice pulls at each speed setting. Peak force meas­urements were obtained from the best of three trials at speed settings S-0, S-2, S-4, S-6, and S-8. After a five-minute rest period, each subject performed a 45-second muscular total work and fatigue test. The total work and fatigue test was performed at the high tension speed setting of S-0 (0.9 m/ sec). The digital work integrator recorded the total work produced during the test. We measured fatigue as the per­centage of decline of peak force from the average of the first three and last three arm pulls. As stated previously, power was calculated from the results of the work tests and the time of the pull. We instructed each subject to give a maximal effort on every muscular contraction. Verbal encouragement was given during each test. * Cybex, Div of Lumex, 2100 Smithtown Ave, Ronkonkoma, NY 11779.

† Isokinetic. Inc, PO Box 6397, Albany, CA 94706.

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RESEARCH

TABLE 2 Cybex® II Dynamometer Results: Peak Torque Values of Knee Extensor" and Flexor Muscles at Predetermined Angular Velocities

Angular Velocity

0°/sec Flexion Extension

60°/sec Flexion Extension

120°/sec Flexion Extension

180°/sec Flexion Extension

240°/sec Flexion Extension

300°/sec Flexion Extension

Pretrial (Nm)

32.4 85.6 37.0 70.5 28.7 45.4 19.9 30.9 16.1 22.8 13.4 14.2

s

19.9 25.9 30.1 34.2 26.9 28.2 22.1 23.0 18.2 19.2 16.4 15.3

Midtrial (Nm)

42.6 92.1 47.5 87.5 36.1 57.4 27.3 42.9 24.8 34.4 24.4 27.1

s

16.9 32.1 31.5 40.8 26.6 32.4 20.6 25.5 20.5 23.2 21.4 20.5

Posttrial (Nm)

43.4 90.8 46.0 79.5 34.9 54.2 26.4 37.1 22.6 27.4 19.1 21.0

s

18.9 32.4 27.5 32.7 22.4 26.4 19.1 17.8 16.7 15.3 14.8 14.2

Pretrial to

Midtrial 31.8 7.6

28.2 24.0 25.5 26.3 36.7 39.8 53.8 51.2 81.8 90.5

Difference (%)

Midtrial to

Posttrial 1.9

-1.4 -3.2 -9.1 -3.3 -5.6 -3.3

-13.5 -8.9

-20.3 -21.7 -22.5

Pretrial to

Posttrial 33.9 6.0

24.3 12.7 21.6 19.4 32.7 20.1 40.3 20.1 42.5 47.8

Aquatic Exercise Program All subjects participated in a 10-week exercise program

consisting of freestyle swimming and shallow water calisthen­ics, as outlined by the President's Council on Physical Fitness and Sports7 and Getchell and Anderson.9 The program site was a 25-m by 15-m instructional facility. We regulated water temperature within a range of 25° to 27.5°C (77°-81.5°F). Exercise prescription was based on the guidelines recom­mended by the American College of Sports Medicine.10 The frequency of exercise was set at 3 one-hour exercise sessions each week; training intensity was established at 60 to 75 percent of the subject's estimated maximal heart rate. We based progression of exercise intensity and duration on sub-maximal heart rate; subjective feelings of fatigue; periodic clinical assessment by attending physicians; and monitoring of resting, recovery, and maximal training heart-rate re­sponses.

Data Analysis We used a two-way analysis of variance (SPSS computer

program) to test for significance of effects for the following variables: muscular torque, force, work, and power at selected movement speeds. The percentage of change was computed for the torque, work, and fatigue variables by the following formula:

(1)

RESULTS Torque and Force

Table 2 presents the mean peak torque data from the dynamometer testing for knee flexion and extension. Peak torque measurements for the knee extensor muscles indicated significant improvement (p < .05) from pretrial to midtrial

TABLE 3 Biokinetic Swim-Bench Results: Mean-Force, Work, and Power Values at Predetermined Speed Settings for Upper Extremities

Variable

Forcea (N)

s Workb (Nm)

s Powerc

(Nm/sec)

s

Pre­trial

129.2 57.9

89.3 43.4

57.8 43.0

Mid-trial S-0

148.5 57.6

105.6 38.8

77.9 49.6

Post-trial

189.5 65.3

126.3 46.3

92.0 47.5

Pre­trial

80.3 61.3

42.4 37.0

59.6 55.8

Mid-trial S-2

99.5 58.1

56.6 35.6

80.9 57.0

Post-trial

128.2 59.2

66.4 37.2

95.5 60.3

Pre­trial

53.8 46.8

25.0 24.0

57.2 54.1

Mid-trial S-4

69.9 53.7

32.6 28.5

76.8 64.6

Post-trial

87.9 47.1

39.2 26.4

97.0 58.5

Pre­trial

32.3 32.5

15.2 16.3

61.5 55.9

Mid-trial S-6

42.9 36.1

19.6 18.3

75.6 67.1

Post-trial

58.8 46.7

21.7 20.0

81.9 61.3

Pre­trial

16.0 24.0

4.3 8.6

21.7 43.2

Mid-trial S-8

24.9 27.0

9.8 12.0

52.6 56.8

Post-trial

29.6 32.0

11.9 12.7

66.2 66.1

a All extension pretrial to midtrial values except 0°/sec significant (p < .05).

a Significant (p < .05) between trials and speeds. b Significant (p < .05) for all trials except S-6. c Significant (p < .05) pretrial to posttrial except S-6.

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for all designated angular velocities except for 0%ec. We found no statistical difference in mean peak torque values for knee flexor muscles from pretrial to midtrial nor any signifi­cant differences for each of the respective angular velocities. All flexor and extensor peak torque values except the knee flexors at 0°/sec decreased between the midtrial and posttrial. Peak torque from pretrial to posttrial and midtrial to posttrial for both the knee extensor and flexor musculature indicated nonsignificant difference for all of the angular velocities. Table 2 also gives percentage of change between the peak torque values from the pretrial to midtrial, midtrial to posttrial, and pretrial to posttrial for the knee flexor and extensor muscles.

Table 3 presents the mean force values for the upper extremities at the various speed settings for the swim bench. At all of the speed settings, two-way analysis of variance revealed a significant difference (p < .05) in peak force values for the three testing periods and a significant difference (p < .05) between the speeds of movement. Mean force output was greatest at the high tension speed settings of S-0 and S-2; the force output progressively declined at the lower tension speed setting of S-4, S-6, and S-8, respectively. The percentage of increase in mean force values from pretrial to posttrial ranged from 46.7 to 85.0 percent.

Muscular Work and Fatigue

Table 4 outlines group means for total muscular work and fatigue (percent decrement in peak torque) for the Cybex®. The total work of the knee extensor muscles increased by 192 percent from pretrial to midtrial and 330 percent from the pretrial to posttrial. The total work improvement was statis­tically significant (p < .05). The lower extremities' fatigue values (percentage of decline in peak torque) showed a statis­tically significant (p < .05) decrease. The absolute differences in the fatigue values were 12.84 and 14.14 percent for the pretrial to midtrial and pretrial to posttrial, respectively.

As determined by significance testing (p < .05), work for the upper extremities improved at all of the speed settings, with the exception of S-6. As was characteristic of force, work progressively decreased as the speed setting (velocity) in­

creased. Table 3 presents mean data for work. The total work as measured during the 45-second, swim-bench test increased significantly (p < .05) from pretrial to posttrial. The percent­age of increase from pretrial to midtrial was 39 percent, and the increase in total work from the pretrial to posttrial was 82 percent (Tab. 4). As for the swim-bench fatigue values, no statistically significant difference could be found between trials. The data showed that the fatigue value increased (14%) from the prefatigue to postfatigue test trial.

Power At the .05 level of significance, mean power of the upper

extremities improved (pretrial to posttrial) at all the speed settings other than S-6. Peak power was recorded at S-4 posttrial (97.0 Nm/sec); at S-8 pretrial (21.7 Nm/sec), power output was lower than at all other speed settings. Mean power values can be found in Table 3.

DISCUSSION

The results of this investigation indicated that individuals with MS who participated in a program of aquatic exercise were able to overcome some of the neuromuscular deficits characteristic of the disease process. Factors that may have influenced the outcome of the muscular force, torque, work, and fatigue measurements included 1) the specificity of train­ing principle, 2) neuropathological influences of MS on skel­etal muscle, 3) physical inactivity, and 4) diurnal physiological alterations.

Isokinetic dynamometry data revealed that maximal peak torque for the knee extensor muscles was recorded at the isometric setting (0°/sec). No statistical differences were ob­tained, however, for the three trial sessions at the isometric setting. Similar results were obtained by Larsson, who strength-trained previously sedentary adult men.11 Larsson found that although maximum peak torque was produced at the isometric setting, no statistical significance could be found when comparing the results of pretrial, midtrial, and posttrial. The insignificant results for isometric peak torque may indi-

TABLE 4 Total Work Production" and Fatigueb for Upper and Lower Extremities

Test Equipment

Cybex® II total work (Nm) fatigue (% decline

in force) Swim bench

total work (Nm) fatigue (% decline

in force)

Pretrial Period

1078.90 55.15

1093.40 29.78

s

817.80 11.02

658.60 15.26

Midtrial Period

3151.70 42.31

1522.00 31.57

s

1780.50 12.57

294.20 14.09

Posttrial Period

4641.40 41.01

1990.80 33.95

s

1084.40 14.97

1091.70 18.93

Pretrial to

Midtrial

192.1 -23.3

39.2 6.0

Difference (%)

Midtrial to

Posttrial

47.3 -3.1

30.8 7.5

Pretrial to

Posttrial

330.2 -25.6

82.1c

14.0

a Significant (p < .05) between trials. b Significant (p < .05) between trials. c Significant (p < .05) pretrial to posttrial.

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RESEARCH

cate the lack of training specificity between dynamic and static exercise. Investigations by Osternig and associates12 and Wolf13 have shown that isometric peak torque demonstrated a low correlation with dynamic peak torque, and the patterns of motor unit recruitment varied depending on whether the nature of muscular contraction was static or dynamic. Al­though dynamic peak torque values for the knee extensors showed a significant increase from pretrial to midtrial dyna­mometer measurements in our study, the results failed to indicate any improvement in dynamic peak torque for the knee flexor muscles. The lack of muscular torque gains for the knee flexors may be related to the general muscular weakness and contracture problems faced by patients with MS.5, 14 The extent of pyramidal pathway involvement may have also compromised the ability of the knee flexor muscu­lature to improve with exercise. Birch et al stated that training cannot influence irrevocable CNS damage.15

The general trend for the swim-bench data indicated a significant improvement in the components of strength (force, work, and power) for all three experimental trials. The reason why the strength components gains were most evident for the upper extremities and not for the lower extremities may be related to discrepancies in testing protocols for the dynamom­eter and swim bench. Specificity of training may have also been a key factor influencing the outcome of the force and torque measurements. Costill and associates have stated that devices that measure strength must duplicate the actual bio-mechanical patterns of a particular skill.16

Swim-bench measurements revealed that at the high ten­sion settings of S-0 and S-2 and medium tension setting of S-4, force, work, and power showed significant gains; however, at the low tension settings of S-6 and S-8, significant improve­ments in force, work, and power were not quite so dramatic. The somewhat variable findings at the faster velocities may be related to the duration and intensity of the aerobically-oriented exercise. Elliott stated that muscles that are trained at fast velocities become capable of improving strength at both fast and slow speeds; however, if training takes place under conditions of high resistance or slow velocities or both,

quickness and power are sacrificed.17 The inability to produce peak torque at the faster velocities may also be because of the demyelinating-denervating process so characteristic of MS. Edstrom hypothesized that in upper motor neuron lesions (with paresis and spasticity), there may be selective disuse of high threshold motor units, which innervate fast twitch (FT) fibers, and overuse of low threshold motor units/which in­nervate slow twitch (ST) muscle fibers.18 This situation would then result in atrophy of the high threshold motor units and FT fibers and in hypertrophy of the low threshold motor units and ST fibers. The predominance of ST muscle fibers in upper motor neuron lesions may indicate that in patients with MS, muscle function may be compromised.

Perhaps, the most universal symptom encountered by per­sons with MS is fatigue. Typically, patients with MS follow a diurnal cycle in which they awaken in the morning fairly rested, progressively fatigue throughout the day, and recover in the evening.19 The results of this investigation indicated that muscular work and muscular fatigability can be dramat­ically improved in patients with MS. The results indicated an 82 percent increase in the total work measurement for the upper extremities and a 330 percent increase in the total work measurement for the lower extremities. The percent decline in peak torque (fatigue measure) for the lower extremities decreased from 55 percent to 41 percent; a significant im­provement in the ability of the muscles to maintain peak torque.

CONCLUSION

In light of the mentioned factors that may have influenced the results of this investigation, we concluded that an aquatic exercise program is not harmful to the muscular strength and endurance of patients with MS. The results, although mixed, did indicate that some positive changes in muscular strength (force and torque), fatigue, work, and power can be expected from an aquatic exercise program. The small sample group and mixed results of this study would indicate the need for further research in this particular area.

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4. Gordon EE, Carlson EE: Changing attitude toward multiple sclerosis. JAMA 147:720-723,1951

5. Cailliet R: Exercise in multiple sclerosis. In Basmajian JV (ed): Therapeutic Exercise, ed 3. Baltimore, MD, Williams & Wilkins, 1980, pp 375-388

6. Russell RW: Disseminated sclerosis: Rest-exercise therapy. In Russell RW (ed): Multiple Sclerosis: Control of the Disease. New York, NY, Pergamon Press Inc, 1976, pp 67-76

7. President's Council on Physical Fitness and Sports: Aqua Dynamics: Physical Conditioning Through Water Exercises. Washington, DC, United States Government Printing Office, 1977, 0-250-914, pp 33

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9. Getchell B, Anderson W: Being Fit: A Personal Guide. New York, NY, John Wiley & Sons Inc, 1982, p 312

10. American College of Sports Medicine: Guidelines for Graded Exercise Testing and Exercise Prescription, ed 2. Philadelphia, PA, Lea & Febiger, 1980, p 151

11. Larsson L: Physical training effects on muscle morphology in sedentary males at different ages. Med Sci Sports Exerc, 14:203-206, 1982

12. Osternig LR, Bates BT, James SL: Isokinetic and isometric torque force relationships. Arch Phys Med Rehabil 58:254-257, 1977

13. Wolf SL: The morphological and functional basis of therapeutic exercise. In Basmajian JV (ed): Therapeutic Exercise. Baltimore, MD, Williams & Wilkins, 1980, p 63

14. Rusk HA: Rehabilitation Medicine. St. Louis, MO, CV Mosby Co, 1977, p 460

15. Birch HG, Proctor F, Bortner M, et al: Perception in hemiplegia: I. Judgment of vertical and horizontal by hemiplegic patients. Arch Phys Med Rehabil 41:19-27,1960

16. Costill DL, Sharp RL, Troup J: Muscle strength: Contributions to sprint swimming. In Flavell ER (ed): Biokinetic Strength Training. Albany, CA, Isokinetics, Inc, 1981, p 216

17. Elliott J: Assessing muscle strength isokinetically. JAMA 240:2408-2410, 1978

18. Edstrom L: Selective changes in the size of red and white muscle fibers in upper motor lesions and parkinsonism. J Neurol Sci 11:537-550, 1970

19. O'Sullivan SB, Cullen KE, Schmitz TJ: Physical Rehabilitation: Evaluation and Treatment Procedures. Philadelphia, PA, F.A. Davis Co, 1981, pp 249-257

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1984; 64:653-657.PHYS THER. Gale M Gehlsen, Susan A Grigsby and Donald M WinantMultiple SclerosisMuscular Strength and Endurance of Patients with Effects of an Aquatic Fitness Program on the

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