Alcohol,Vol. 7, pp. 361-366. ©PergamonPress pie, 1990. Printedin the U.S.A.
0741-8329/90$3.00 + .00
A Survey of Muscle Function in Detoxified Alcoholics D A V I D R. P E N D E R G A S T , * J A M E S L. Y O R K t 1 A N D N A D I N E M. HSHER:~
*Department of Physiology, State University of New York at Buffalo ~NYS Division of Alcoholism and Alcohol Abuse, Research Institute on Alcoholism, Buffalo, NY 14203 ~:Department of Rehabilitation Medicine, State University of New York at Buffalo Received 7 August; Accepted 18 January 1990
PENDERGAST, D. R., J. L. YORK AND N. M. HSHER. A surveyof musclefunction in detoxifiedalcoholics. ALCOHOL 7(4) 361-366, 1990.--Selected characteristics of arm and leg muscle contraction were examined in a racially mixed group of male detoxified alcoholics (N = 45, ages 20--49) and age-matched controls (N = 75), Lifetime drinking histories estimated the mean lifetime consumption of ethanol to be 8.96, 12.1 and 20.4 kg ethanol/kg body weight for alcoholic subjects aged 20-29, 30-39 and 40--49, respectively. The severity of the alcohol dependence syndrome (ADS scale) was marked in alcoholics, but was not age-dependent. Alcoholics did not differ significantly from controls on health status or physical activity scales. The performance of alcoholic subjects was impaired on all muscle function measures, with relatively more impairment found in older alcoholics. Maximal knee extension force generated at 3 muscle lengths (hip, angle, 45°, 90°, 180°) was impaired only in alcoholics 30--49years of age. Forearm (handgrip) muscle strength was impaired in all age groups of alcoholics. Maximal muscle (biceps) contraction speed at 3 levels of resistance was impaired only in alcoholics in their fifth decade of life. The greatest deficit in alcoholics (all age groups) was observed in the anaerobic power (bicycle ergnmeter) test. Thus, the magnitude of dysfunction and the extent of age-relatedness was found to be a function of the muscle test employed. Age-relatedness
Alcohol consumption
Alcoholics
Muscle performance
IT has been known for over two decades that excessive alcohol consumption in man may be accompanied clinically by muscle atrophy and weakness (7,17). This disorder may be present in varying degrees in as many as 25--60% of the patients in clinical alcoholism facilities (8, 22, 33). Controlled studies using animal models have verified the direct role of alcohol in alcohol myopathy, although nutritional factors have not been ruled out entirely (6, 10, 15). The diagnosis of alcoholic myopathy in man historically has focused upon clinical symptoms (such as pain, weakness or muscle wasting) with verification from biochemical (creatine phosphokinase), histological (fiber necrosis), or electrophysiologieal (EMG) measures (9, 19, 20). In spite of the high frequency of myopathy and its predicted effect on functional performance, little is known about the mechanisms responsible for the muscle wasting and weakness. Also noticeably lacking are studies whose aim is the quantification of muscle contractile performance (i.e., contraction characteristics of intact muscle groups of the arms and legs) and its correlation with the results from clinical evaluations. Traditionally, muscle function has been evaluated in the clinic by relatively subjective and inaccurate manual muscle-testing procedures which focus upon measures of strength (3). More quantitative methods of assessing strength have been proposed (2) and utilized in normal subjects and patients with neuromuscular
Physical activity
disorders. In general, muscle function can be considered to be a cluster of variables, including the ability to generate maximal force, the ability to sustain a force over a period of time (or resist fatigue), the ability to contract at maximal speed against fixed resistances, the ability to supply peak metabolic power, and the ability to sustain the metabolic power over a period of time (23). These characteristics can be considered independently from the ability to transport oxygen (oxygen consumption, cardiac output, muscle blood flow, mitochondrial function) as they may involve primarily fast twitch muscle fibers contracting under anaerobic conditions. The purpose of this study was to provide a description of these contraction characteristics of skeletal muscle in alcoholics of varying ages and compare them to age-matched control subjects. The goal was to provide an overview of muscle performance capabilities that are related to the execution of practical work- and leisure-related activities. METHOD
Subjects Forty-five male subjects between the ages of 20 and 50 were recruited from three local alcoholism treatment programs. The three progranm included a state-supported, a county-supported and a privately operated unit. In addition, 75 men ages 20-50 were
1Requests for reprints should be addressed to Dr. James L. York, Research Institute on Alcoholism, 1021 Main Street, Buffalo, NY 14203.
361
362
recruited from the metropolitan community and served as a comparison group. These control subjects had been identified and tested at an earlier time (11) and may be considered to be "social" drinkers. Alcoholic subjects were volunteers and were generally tested in the fourth week after admission to their treatment programs. They were screened for drug abuse and for medical conditions that would place them at risk during the testing or would have predictable effects upon muscle performance (i.e., hepatitis, pancreatitis, history of head injuries or seizures, organic brain damage, emphysema, chronic pulmonary disease and heart disease). Approximately 30 percent of the volunteers from the alcoholism treatment facilities met the criterion for admission to the study. Although most of the alcoholic subjects had been drinking prior to admission to the treatment program, they were alcohol free during the 3-4 weeks preceding testing. The subjects who participated in the study were not screened specifically for indications of peripheral neuropathy or myopathy.
Health, Activity, and Alcohol Use Assessment Three self-administered forms were given to subjects in order to obtain information regarding characteristics that might be related to task performance. Health and Activity questionnaires (developed by Dr. David Pendergast, Department of Physiology, SUNY at Buffalo, copies and scoring guides available upon request) contained questions regarding current and past medical problems, current medications, and physical symptomatology, and the Activity questionnaire contained questions regarding the type and intensity of recreational, home, and work-related physical activities engaged in by subjects. Each item on the Health and Activity questionnaires was given a score depending, respectively, upon the severity of the symptoms or illness and upon the amount of energy expended. Thus, higher scores represented greater levels of physical activity (Activity questionnaire) and better health (Health questionnaire). The Alcohol Dependence Scale [ADS (29)] contained 25 questions related to the extent of psychological, physical and social dysfunction resulting from alcohol use during the 12 months preceding testing. Scores on this form may range from 0 to 47, and may be interpreted to reflect the level of physical or psychological dependence on alcohol. The Lifetime Drinking History questionnaire (30) was utilized to document alcohol consumption throughout the subject's drinking career, starting with the age at which regular drinking (at least once per month) began. Quantity, frequency, and type of beverage, as well as the influence of life events on drinking behavior were recorded for each phase of the subject's drinking career. Data from the individual phases were summed to obtain lifetime drinking measures. The drinking history interview was not given to control subjects, nor were control subjects specifically screened for the presence of alcoholism.
Muscle Function Measures In this survey of muscle function, four indirect techniques were selected, each of which estimates an important functional characteristic of skeletal muscle. The four techniques were utilized in four different muscle groups to avoid carryover effects of fatigue on subsequent tests. As a survey study, our goal was to uncover deficits in muscles that could provide clues for more extensive future studies. Maximal strength. The maximal tension that a muscle can generate is a function of the muscle mass (cross-sectional area) and the percentage of the muscle that is made up of fast twitch muscle fibers. Inasmuch as the composition of the leg muscles is approximately 60 percent slow- and 40 percent fast-
PENDERGAST, YORK AND FISHER
fibers, while those of the arms have roughly the reverse ratio, knee extension force and hand grip strength were evaluated to determine if alcoholism had a preferential effect on one type of fiber or another. The maximal isometric voluntary knee extension force was determined on a specially designed bench. Subjects were positioned to eliminate involvement of all muscles except the quadriceps group (anterior thigh). The knee was positioned at 90 ° of flexion and measurements were made with the hip at 45 ° (leaning forward from sitting position), 90 ° (sitting upright) and 180 ° (reclining) of flexion. Under these conditions (90 ° knee angle) the rectus femoris contributes approximately 60 percent of the force, while the vastus lateralis and medialis contribute roughly 40 percent (5). As the hip angle is increased (45-90-180), the rectus femoris muscle is stretched (as the origin is on the pelvis), while the vastus lateralis and medialis remain at their initial length (as they cross only the knee). As the muscle is lengthened, muscular force increases in the rectus femoris until its resting length is reached (hip angle of 180). Force was measured by an electronic strain gauge (Schaveitz, 0-200 kg) which was calibrated prior to each subject. Three trials were given under each condition, with the highest being utilized for subsequent analysis. Maximal isometric force for the forearm was measured by a standard hand-grip dynamometer (Stoelting). This technique was chosen due to its ease of administration and because of the high correlation between grip strength and maximal strength of other upper body muscles. In addition to the measurement of maximal grip force, hand grip fatigue was also measured by instructing subjects to grasp the grip at 80 percent of their maximal force and to maintain that force or as close to it as possible for a 90-second test. The 80 percent level was selected as it represents the maximal voluntary recruitment of fast, slow and intermediate muscle fibers. This procedure allowed for the construction of a fatigue curve with force readings taken every 15 seconds. Contraction velocity. The velocity with which a muscle can shorten is a function of the length of the fibers, the type and number of motor units activated, and the resistance to be overcome. Assuming a maximal voluntary contraction, the velocity of shortening is dependent upon the resistance, after the initial elastic elements are charged and prior to the development of momentum. Elbow flexion (biceps contraction) was selected as the movement to be analyzed. An apparatus was designed that permitted resistances (loads) of different sizes to be evaluated. To this end, a specially designed rack was utilized whereby a bar had to be lifted vertically with the biceps muscles of both arms. With the body fixed in an upright standing position, the bar was grasped at the level of the thighs with both hands at approximately full downward arm extension and was jerked to shoulder height as rapidly as possible by means of elbow flexion (full biceps contraction). The time to cover a set distance was measured (electronic timer, velocity=distance/time), disregarding the first 10 cm (elastic component) and last 10 cm (momentum) of movement. Three trials were given for each of the three resistances; a yard stick (0.1 kg), a barbell (1.7 kg), and a barbell with weights (8.4 kg). Metabolic power. The primary goal of the present study was to survey alterations in muscle function resulting from chronic alcohol exposure. To accomplish this from a metabolic perspective, we chose to examine peak anaerobic power and the ability to sustain anaerobic power over a short period of time (30 seconds). Specifically, the maximal power that could be developed and sustained while pedalling a bicycle ergometer was measured. Subjects were given a 2-minute warm-up (low intensity) which was followed by a 30-second rest. The subject was then instructed to increase the revolutions on the bike to a personal maximal value. A fixed load (based upon body weight, Wingate Power Test) was then applied within a 2-5-second period. As the load
MUSCLE FUNCTION IN ALCOHOLICS
363 60
TABLE 1 PHYSICALCHARACTERISTICSOF SUBJECTS Age Group
50
20-29
30-39
40-49
Age (Year) Alcoholic Control
25.8 25.7
34.3 33.5
43.1 44.7
Weight (kg) Alcoholic Control
73.2* 79.5
74.0* 80.8
74.3* 84.8
219.3 (5.4) 228.8 (8.4)
214.0 (19.2) 223.0 (12.8)
210.9 (11.8) 224.7 (11.0)
Health Alcoholic Control Activity Alcoholic Control
40
30
/
20
10
4930 (5979) 5614 (6958)
3442 (3335) 3495 (2842)
2843 (3143) 1723 (1554)
Weight was determined using a physician's scale. Health and Activity scores were obtained using self-administered questionnaires (see the Method section). Values represent means --- standard deviations. *p
0741-8329/90$3.00 + .00
A Survey of Muscle Function in Detoxified Alcoholics D A V I D R. P E N D E R G A S T , * J A M E S L. Y O R K t 1 A N D N A D I N E M. HSHER:~
*Department of Physiology, State University of New York at Buffalo ~NYS Division of Alcoholism and Alcohol Abuse, Research Institute on Alcoholism, Buffalo, NY 14203 ~:Department of Rehabilitation Medicine, State University of New York at Buffalo Received 7 August; Accepted 18 January 1990
PENDERGAST, D. R., J. L. YORK AND N. M. HSHER. A surveyof musclefunction in detoxifiedalcoholics. ALCOHOL 7(4) 361-366, 1990.--Selected characteristics of arm and leg muscle contraction were examined in a racially mixed group of male detoxified alcoholics (N = 45, ages 20--49) and age-matched controls (N = 75), Lifetime drinking histories estimated the mean lifetime consumption of ethanol to be 8.96, 12.1 and 20.4 kg ethanol/kg body weight for alcoholic subjects aged 20-29, 30-39 and 40--49, respectively. The severity of the alcohol dependence syndrome (ADS scale) was marked in alcoholics, but was not age-dependent. Alcoholics did not differ significantly from controls on health status or physical activity scales. The performance of alcoholic subjects was impaired on all muscle function measures, with relatively more impairment found in older alcoholics. Maximal knee extension force generated at 3 muscle lengths (hip, angle, 45°, 90°, 180°) was impaired only in alcoholics 30--49years of age. Forearm (handgrip) muscle strength was impaired in all age groups of alcoholics. Maximal muscle (biceps) contraction speed at 3 levels of resistance was impaired only in alcoholics in their fifth decade of life. The greatest deficit in alcoholics (all age groups) was observed in the anaerobic power (bicycle ergnmeter) test. Thus, the magnitude of dysfunction and the extent of age-relatedness was found to be a function of the muscle test employed. Age-relatedness
Alcohol consumption
Alcoholics
Muscle performance
IT has been known for over two decades that excessive alcohol consumption in man may be accompanied clinically by muscle atrophy and weakness (7,17). This disorder may be present in varying degrees in as many as 25--60% of the patients in clinical alcoholism facilities (8, 22, 33). Controlled studies using animal models have verified the direct role of alcohol in alcohol myopathy, although nutritional factors have not been ruled out entirely (6, 10, 15). The diagnosis of alcoholic myopathy in man historically has focused upon clinical symptoms (such as pain, weakness or muscle wasting) with verification from biochemical (creatine phosphokinase), histological (fiber necrosis), or electrophysiologieal (EMG) measures (9, 19, 20). In spite of the high frequency of myopathy and its predicted effect on functional performance, little is known about the mechanisms responsible for the muscle wasting and weakness. Also noticeably lacking are studies whose aim is the quantification of muscle contractile performance (i.e., contraction characteristics of intact muscle groups of the arms and legs) and its correlation with the results from clinical evaluations. Traditionally, muscle function has been evaluated in the clinic by relatively subjective and inaccurate manual muscle-testing procedures which focus upon measures of strength (3). More quantitative methods of assessing strength have been proposed (2) and utilized in normal subjects and patients with neuromuscular
Physical activity
disorders. In general, muscle function can be considered to be a cluster of variables, including the ability to generate maximal force, the ability to sustain a force over a period of time (or resist fatigue), the ability to contract at maximal speed against fixed resistances, the ability to supply peak metabolic power, and the ability to sustain the metabolic power over a period of time (23). These characteristics can be considered independently from the ability to transport oxygen (oxygen consumption, cardiac output, muscle blood flow, mitochondrial function) as they may involve primarily fast twitch muscle fibers contracting under anaerobic conditions. The purpose of this study was to provide a description of these contraction characteristics of skeletal muscle in alcoholics of varying ages and compare them to age-matched control subjects. The goal was to provide an overview of muscle performance capabilities that are related to the execution of practical work- and leisure-related activities. METHOD
Subjects Forty-five male subjects between the ages of 20 and 50 were recruited from three local alcoholism treatment programs. The three progranm included a state-supported, a county-supported and a privately operated unit. In addition, 75 men ages 20-50 were
1Requests for reprints should be addressed to Dr. James L. York, Research Institute on Alcoholism, 1021 Main Street, Buffalo, NY 14203.
361
362
recruited from the metropolitan community and served as a comparison group. These control subjects had been identified and tested at an earlier time (11) and may be considered to be "social" drinkers. Alcoholic subjects were volunteers and were generally tested in the fourth week after admission to their treatment programs. They were screened for drug abuse and for medical conditions that would place them at risk during the testing or would have predictable effects upon muscle performance (i.e., hepatitis, pancreatitis, history of head injuries or seizures, organic brain damage, emphysema, chronic pulmonary disease and heart disease). Approximately 30 percent of the volunteers from the alcoholism treatment facilities met the criterion for admission to the study. Although most of the alcoholic subjects had been drinking prior to admission to the treatment program, they were alcohol free during the 3-4 weeks preceding testing. The subjects who participated in the study were not screened specifically for indications of peripheral neuropathy or myopathy.
Health, Activity, and Alcohol Use Assessment Three self-administered forms were given to subjects in order to obtain information regarding characteristics that might be related to task performance. Health and Activity questionnaires (developed by Dr. David Pendergast, Department of Physiology, SUNY at Buffalo, copies and scoring guides available upon request) contained questions regarding current and past medical problems, current medications, and physical symptomatology, and the Activity questionnaire contained questions regarding the type and intensity of recreational, home, and work-related physical activities engaged in by subjects. Each item on the Health and Activity questionnaires was given a score depending, respectively, upon the severity of the symptoms or illness and upon the amount of energy expended. Thus, higher scores represented greater levels of physical activity (Activity questionnaire) and better health (Health questionnaire). The Alcohol Dependence Scale [ADS (29)] contained 25 questions related to the extent of psychological, physical and social dysfunction resulting from alcohol use during the 12 months preceding testing. Scores on this form may range from 0 to 47, and may be interpreted to reflect the level of physical or psychological dependence on alcohol. The Lifetime Drinking History questionnaire (30) was utilized to document alcohol consumption throughout the subject's drinking career, starting with the age at which regular drinking (at least once per month) began. Quantity, frequency, and type of beverage, as well as the influence of life events on drinking behavior were recorded for each phase of the subject's drinking career. Data from the individual phases were summed to obtain lifetime drinking measures. The drinking history interview was not given to control subjects, nor were control subjects specifically screened for the presence of alcoholism.
Muscle Function Measures In this survey of muscle function, four indirect techniques were selected, each of which estimates an important functional characteristic of skeletal muscle. The four techniques were utilized in four different muscle groups to avoid carryover effects of fatigue on subsequent tests. As a survey study, our goal was to uncover deficits in muscles that could provide clues for more extensive future studies. Maximal strength. The maximal tension that a muscle can generate is a function of the muscle mass (cross-sectional area) and the percentage of the muscle that is made up of fast twitch muscle fibers. Inasmuch as the composition of the leg muscles is approximately 60 percent slow- and 40 percent fast-
PENDERGAST, YORK AND FISHER
fibers, while those of the arms have roughly the reverse ratio, knee extension force and hand grip strength were evaluated to determine if alcoholism had a preferential effect on one type of fiber or another. The maximal isometric voluntary knee extension force was determined on a specially designed bench. Subjects were positioned to eliminate involvement of all muscles except the quadriceps group (anterior thigh). The knee was positioned at 90 ° of flexion and measurements were made with the hip at 45 ° (leaning forward from sitting position), 90 ° (sitting upright) and 180 ° (reclining) of flexion. Under these conditions (90 ° knee angle) the rectus femoris contributes approximately 60 percent of the force, while the vastus lateralis and medialis contribute roughly 40 percent (5). As the hip angle is increased (45-90-180), the rectus femoris muscle is stretched (as the origin is on the pelvis), while the vastus lateralis and medialis remain at their initial length (as they cross only the knee). As the muscle is lengthened, muscular force increases in the rectus femoris until its resting length is reached (hip angle of 180). Force was measured by an electronic strain gauge (Schaveitz, 0-200 kg) which was calibrated prior to each subject. Three trials were given under each condition, with the highest being utilized for subsequent analysis. Maximal isometric force for the forearm was measured by a standard hand-grip dynamometer (Stoelting). This technique was chosen due to its ease of administration and because of the high correlation between grip strength and maximal strength of other upper body muscles. In addition to the measurement of maximal grip force, hand grip fatigue was also measured by instructing subjects to grasp the grip at 80 percent of their maximal force and to maintain that force or as close to it as possible for a 90-second test. The 80 percent level was selected as it represents the maximal voluntary recruitment of fast, slow and intermediate muscle fibers. This procedure allowed for the construction of a fatigue curve with force readings taken every 15 seconds. Contraction velocity. The velocity with which a muscle can shorten is a function of the length of the fibers, the type and number of motor units activated, and the resistance to be overcome. Assuming a maximal voluntary contraction, the velocity of shortening is dependent upon the resistance, after the initial elastic elements are charged and prior to the development of momentum. Elbow flexion (biceps contraction) was selected as the movement to be analyzed. An apparatus was designed that permitted resistances (loads) of different sizes to be evaluated. To this end, a specially designed rack was utilized whereby a bar had to be lifted vertically with the biceps muscles of both arms. With the body fixed in an upright standing position, the bar was grasped at the level of the thighs with both hands at approximately full downward arm extension and was jerked to shoulder height as rapidly as possible by means of elbow flexion (full biceps contraction). The time to cover a set distance was measured (electronic timer, velocity=distance/time), disregarding the first 10 cm (elastic component) and last 10 cm (momentum) of movement. Three trials were given for each of the three resistances; a yard stick (0.1 kg), a barbell (1.7 kg), and a barbell with weights (8.4 kg). Metabolic power. The primary goal of the present study was to survey alterations in muscle function resulting from chronic alcohol exposure. To accomplish this from a metabolic perspective, we chose to examine peak anaerobic power and the ability to sustain anaerobic power over a short period of time (30 seconds). Specifically, the maximal power that could be developed and sustained while pedalling a bicycle ergometer was measured. Subjects were given a 2-minute warm-up (low intensity) which was followed by a 30-second rest. The subject was then instructed to increase the revolutions on the bike to a personal maximal value. A fixed load (based upon body weight, Wingate Power Test) was then applied within a 2-5-second period. As the load
MUSCLE FUNCTION IN ALCOHOLICS
363 60
TABLE 1 PHYSICALCHARACTERISTICSOF SUBJECTS Age Group
50
20-29
30-39
40-49
Age (Year) Alcoholic Control
25.8 25.7
34.3 33.5
43.1 44.7
Weight (kg) Alcoholic Control
73.2* 79.5
74.0* 80.8
74.3* 84.8
219.3 (5.4) 228.8 (8.4)
214.0 (19.2) 223.0 (12.8)
210.9 (11.8) 224.7 (11.0)
Health Alcoholic Control Activity Alcoholic Control
40
30
/
20
10
4930 (5979) 5614 (6958)
3442 (3335) 3495 (2842)
2843 (3143) 1723 (1554)
Weight was determined using a physician's scale. Health and Activity scores were obtained using self-administered questionnaires (see the Method section). Values represent means --- standard deviations. *p
