INCREASE
KARL-OLOV
OF MUSCLE TONUS TOBACCO SMOKING FAGERSTR~M*
Smoking Withdrawal Clinic,
AFTER
and K. GUNNAR G~TESTAM
Uller5ker
Hospital.
Uppsala,
Sweden
Abstract-Six subjects smoked half a cigarette with different nicotine levels and inter-puff intervals. EMG readings were taken before, during, and after smokmg from the pars descendens of musculus trapezius. During smoking it was found that the muscle tonus increased in a dosedependent filshion. Two to three minutes after smoking the EMG-level had returned to the initial (pre-smoking) level. The two conllicting phenomena which follow smoking i.e. increased autonomic activity and the feeling of relaxation, are discussed.
INTRODUCTION
Cigarette smoking is a widespread habit which results in serious problems for both the smoking individual and for society. People smoke for a variety of reasons and experience numerous effects which seem to make smoking rewarding. Some of the effects of nicotine which have been reported to increase the probability of smoking are: a reduction of aggression, hostility, and irritability (Hutchinson et al. 1973), a tranquilizing action on the CNS (Brown, 1967), a reduction of bioenergetic deficiency, such as hypoglycemia (Hickey & Harner, 1973) and increased stimulation due to arousal of brain stem mechanisms (Domino, 1967). At a cognitive level, sensorimotor sensations and feelings of relaxation are the most frequently reported reasons for smoking (Tomkins, 1966). One of the single most common reasons for smoking is the sensation of being able to relax more easily while consuming a cigarette. However, the exact nature of this sensation has been difficult to define since relaxation is often an ideosyncratic state. For the purpose of this study it was expedient to divide it into two factors: mental relaxation and skeletal muscle relaxation. The purpose of the present study was to investigate the effect of tobacco smoking on the skeletal muscle tonus. There is evidence that tobacco smoking causes a temporary reduction of the amplitude of the patellar reflex with a corresponding decrease in phasic activity of the quadriceps femoris muscle (Clark & Rand, 1968; Domino & von Baumegarten, 1969; Domino, 1973). Webster (1964) found that a paraplegic patient’s spasticity was dramatically reduced during a test after smoking a cigarette. In order to measure muscle tonus relevant to the feeling of relaxation, an integrated EMG-recording would seem to be more accurate. In the present study, the recording was taken from the pars descendens of musculus trapezius which always has a working tonus when the head is held upright. Since the dose-response relationship is of utmost importance in all research with nicotine as an independent variable, three different dosage levels have been employed in the present study.
METHODS
Six smoking subjects were recruited from the personnel of the hospital. Daily consumption was between 8 and 15 cigarettes. The age range was 2@45 years old. Smoking was not allowed during the 30 min prior to testing. *Requests for reprints should be sent to Karl-Olov Fagerstrcm, Smoking Withdrawal Clinic, Ullerdker Hospital, S-750 17 Uppsala. Sweden. K. Gunnar G6testam is presently Professor of Psychiatry and Chairman of the Institute of Psychiatry at the University of Trondheim, Bstmarka Hospital, PO Box 3008, N-7001 Trondheim, Norway. 203
The three experimental conditions were: (1) smoking half a cigurctte with low nicotine level, (2) smoking half a cigarette with high nicotine level. and (3) smoking one cigarette with high nicotine level rapidly. The low nicotine level cigarette contained 0.9 mg nicotine and 12 mg tar while the high nicotine level cigarette contained I.8 mg nicotine and 23 mg tar. The subjects’ muscle tonus was measured during the three mentioned conditions in counterbalanced order. Sub_jects were not tested more than once ;I day. Prior to the cxperimcnt the electrodes were applied and the subjects were instructctl to sit down and relax for 5 min. The experiment consisted of three I60 s phases: Phase I: Simulated smoking. Hand and mouth movements smoking. An unlit cigarette was used. Phase II: Smoking (one half or one whole cigarette). Phase III: Simulated smoking (same as Phase I). Total time for testing was 4x0 s.
were the same as in actual
Muscle tonus from the back of the neck. the pars dcsccndcns of ~nusculus trape/.ius. was measured by surface silver/silver chloride electrodes embedded in ;I plastic insulator disc. Biogel (Biocom Inc. California) served as a contact medium. The electromyograph was an Autogen 1500b (Autogenic Systems Inc. Berkley, California). The EMG-data were measured in an integrated fashion and recorded in microvolts by the experimenter from a meter-display. The experimenter and the subject sat in the same room but the subject could not see the EMG-display. EMG-rcvdings were taken every 20th s. Besides the EMG-recording. the experimenter also paced the inhalation tempo for the subject in all three phases of simulated or actual smoking. In the rapid-smoking condition. the inter-puff interval was IO s. while in the other tl\o conditions it was 30 s. The EMG-readings were taken between inhalations.
Analyses of variance were computed during cvcry phase in order to obtain diffcrcnccs in trends of muscle tonus between the conditions. The conditions wcrc analyzed and compared by pairs. No significant differences wcrc found between the conditions in Phase I (simulated smoking). In Phase 11 (actual smoking) divcrgcnt trends appcarcd between the conditions. Significant differences in trends bctwccn low and high nicotine levels (1. = 1.31. P < 0.05. d.f. = 7.35) and low and high with t-apic! smoking (I-’ = 7.73. P < 0.001. d.C = 7,;35) were obtained. There was no diffcrencc between high nicotine level and high with rapid smoking (F = 1.33. P < 0.30. d.f. = 7 ‘35). The results arc presented in Fig. 1. In Phase Ill (simulated smoking) the differences in trends lound in Phase II \verc now instead converging. The converging trend between low and high level with rapid
2 oo>
E
I 8Op
Simulated smoking
Smoking
Seconds
Simulated
Increase
of muscle
tonus
after tobacco
205
smoking
smoking (F = 2.95, P < 0.025, d.f. = 7/35) was significant. The other two pairs, high and low nicotine level (F = 1.22, P < 0.35, d.f. = 7/35) and high and high with rapid smoking (F = 1.20, P < 0.35, d.f. = 7/35) did not differ significantly from each other.
DISCUSSION
The results clearly indicate that tobacco consumption affects muscle tonus dose-dependently. Smoking a cigarette with a low nicotine level did not significantly affect the muscle tonus. However, a small but insignificant decrease of muscle tonus was observed (Fig. 1). Smoking a cigarette containing more nicotine increased the tonus, an effect which was further accentuated when the cigarette was smoked rapidly. The usual statement that smoking is relaxing was not supported by the results of this study. The feeling of relaxation can not be inferred from muscular tonus. Smoking rapidly or smoking a cigarette with a high level of nicotine seems. in fact, to have the opposite effect, i.e. increased muscle tonus. The inter-individual variation was so small that smokers’ reported relaxation can not be attributed to that factor. Smokers who seek relaxation, however, can perhaps decrease muscle tonus slightly by choosing cigarettes with low nicotine level and by inhaling more infrequently and shallowly. A plausible explanation of the paradox of smoking as a psychologically relaxing activity without measurable autonomic nervous signs of decreased activation is that of conditioning. The act of smoking frequently occurs in situations which naturally promote a decreased activation and relaxation, e.g. after meals, tea and coffee, after a task has been completed, during a break at work, etc. Gradually smoking in the presence of relaxation-promoting stimuli can in itself produce physiological relaxation, probably through both classical and operant conditioning. In the case of Webster’s (1964) paraplegic patient the testing situation could have been stressful and thus led to a higher experienced central arousal, which correlates positively with spasticity. Smoking a cigarette could thereby have acted as a conditioned anxiety reducing response and psychologically induce a more relaxed state. For an explanation of the difference in measurable EMG between the present study and Clark & Rand (1968) and Domino & von Baumgarten (1969) further research is needed. Some variables to be considered are tonic and phasic EMG, nicotine dosage, type of muscle, and measurement during muscle contraction vs muscle relaxation. In smoking withdrawal therapy, several clients who underwent rapid smoking (Lichtenstein et ul. 1973) responded with increased muscle tension, often to such a degree that they felt shaky and unsteady. Another interesting observation is that some very tense and hyperactive smokers have changed dramatically to much more relaxed and quiet individuals when they stopped smoking. Friends have regarded this change as a manifestation of a considerable “personality change”. However, such a change could also be attributed to the alleviation of both central and peripheral (high muscle tonus) activation. A justifiable conclusion is that the effects of smoking can no longer be regarded as simple and straightforward but rather as the result of highly complex behavior.
REFERENCES Brown, R. R., Relationship between evoked response changes and behavior An&s of the New York Academy ofScience. 1967, 142, lYC200. Clark, M. S. G. & Rand. M. J., Effect of tobacco smoke on knee-ierk of’ Pharmacology
Domino. New
Domino.
and Therapeutics, of’ &&,
E. F. & von Baumgarten.
Phurmacology
and Therapeutics,
small doses of nicotine.
reflex in man.
Europc,rr,t Jourj~trl
1968, 3, 294-302.
E. F., Electroencenhalonraohic York Academy
following
and iY67,
behavioral
arousal
of small
doses
of nicotine.
Ann&
of thr
142, 216-244.
A. M., Tobacco
cigarette
smoking
and patellar
reflex depression,
Clinical
1969, 10, 72-79.
Hickey. R. J. & Harner, E. B., Etiological and biochemical interactions and their relationships to smoking. In W. L. Dunn (Ed.). Smoking behavior: Motiws and irxwltirc,s. Washington: Whinston. 1973. Hutchmson, R. R. & Emeley, G. S., Avoidance, conditioned suppression and aggression response. In W. L. Dunn (Ed.), Smokirlg hehauior: Motiues and iwentices. Washington: Whinston 1973.
206
KARL-01 ov FAGCRSTII~N and K. GUNNAK GBTESTAM
Lichtenstein. E.. Harris, D. E.. Birchler. G. R., Wahl, J. M. & Schmal. D. P.. Comparison of rapid smoking. warm, smoky air. and attention placebo in the modification of smoking behavior. Joun~al c?f Co~~sulti~zq ajld Cliniul P.q~+olo~y, 1973. 40, 91-98. Tomkins. S. S., Psychological model for smoking behavior. Awrica~~ Jour~crl of’ Public Health und t/w Nutims Hculth. 1966. 56(12), 17 20. Webster. D. D.. The dynamic quantitation 01‘ spasticity with automated Integrals 01‘ passive motion reslstancc, Clirlicul Phtrmtrcokyy md Tlwnprutic~.s. 1964. 5. 9OC-908.
KARL-OLOV
OF MUSCLE TONUS TOBACCO SMOKING FAGERSTR~M*
Smoking Withdrawal Clinic,
AFTER
and K. GUNNAR G~TESTAM
Uller5ker
Hospital.
Uppsala,
Sweden
Abstract-Six subjects smoked half a cigarette with different nicotine levels and inter-puff intervals. EMG readings were taken before, during, and after smokmg from the pars descendens of musculus trapezius. During smoking it was found that the muscle tonus increased in a dosedependent filshion. Two to three minutes after smoking the EMG-level had returned to the initial (pre-smoking) level. The two conllicting phenomena which follow smoking i.e. increased autonomic activity and the feeling of relaxation, are discussed.
INTRODUCTION
Cigarette smoking is a widespread habit which results in serious problems for both the smoking individual and for society. People smoke for a variety of reasons and experience numerous effects which seem to make smoking rewarding. Some of the effects of nicotine which have been reported to increase the probability of smoking are: a reduction of aggression, hostility, and irritability (Hutchinson et al. 1973), a tranquilizing action on the CNS (Brown, 1967), a reduction of bioenergetic deficiency, such as hypoglycemia (Hickey & Harner, 1973) and increased stimulation due to arousal of brain stem mechanisms (Domino, 1967). At a cognitive level, sensorimotor sensations and feelings of relaxation are the most frequently reported reasons for smoking (Tomkins, 1966). One of the single most common reasons for smoking is the sensation of being able to relax more easily while consuming a cigarette. However, the exact nature of this sensation has been difficult to define since relaxation is often an ideosyncratic state. For the purpose of this study it was expedient to divide it into two factors: mental relaxation and skeletal muscle relaxation. The purpose of the present study was to investigate the effect of tobacco smoking on the skeletal muscle tonus. There is evidence that tobacco smoking causes a temporary reduction of the amplitude of the patellar reflex with a corresponding decrease in phasic activity of the quadriceps femoris muscle (Clark & Rand, 1968; Domino & von Baumegarten, 1969; Domino, 1973). Webster (1964) found that a paraplegic patient’s spasticity was dramatically reduced during a test after smoking a cigarette. In order to measure muscle tonus relevant to the feeling of relaxation, an integrated EMG-recording would seem to be more accurate. In the present study, the recording was taken from the pars descendens of musculus trapezius which always has a working tonus when the head is held upright. Since the dose-response relationship is of utmost importance in all research with nicotine as an independent variable, three different dosage levels have been employed in the present study.
METHODS
Six smoking subjects were recruited from the personnel of the hospital. Daily consumption was between 8 and 15 cigarettes. The age range was 2@45 years old. Smoking was not allowed during the 30 min prior to testing. *Requests for reprints should be sent to Karl-Olov Fagerstrcm, Smoking Withdrawal Clinic, Ullerdker Hospital, S-750 17 Uppsala. Sweden. K. Gunnar G6testam is presently Professor of Psychiatry and Chairman of the Institute of Psychiatry at the University of Trondheim, Bstmarka Hospital, PO Box 3008, N-7001 Trondheim, Norway. 203
The three experimental conditions were: (1) smoking half a cigurctte with low nicotine level, (2) smoking half a cigarette with high nicotine level. and (3) smoking one cigarette with high nicotine level rapidly. The low nicotine level cigarette contained 0.9 mg nicotine and 12 mg tar while the high nicotine level cigarette contained I.8 mg nicotine and 23 mg tar. The subjects’ muscle tonus was measured during the three mentioned conditions in counterbalanced order. Sub_jects were not tested more than once ;I day. Prior to the cxperimcnt the electrodes were applied and the subjects were instructctl to sit down and relax for 5 min. The experiment consisted of three I60 s phases: Phase I: Simulated smoking. Hand and mouth movements smoking. An unlit cigarette was used. Phase II: Smoking (one half or one whole cigarette). Phase III: Simulated smoking (same as Phase I). Total time for testing was 4x0 s.
were the same as in actual
Muscle tonus from the back of the neck. the pars dcsccndcns of ~nusculus trape/.ius. was measured by surface silver/silver chloride electrodes embedded in ;I plastic insulator disc. Biogel (Biocom Inc. California) served as a contact medium. The electromyograph was an Autogen 1500b (Autogenic Systems Inc. Berkley, California). The EMG-data were measured in an integrated fashion and recorded in microvolts by the experimenter from a meter-display. The experimenter and the subject sat in the same room but the subject could not see the EMG-display. EMG-rcvdings were taken every 20th s. Besides the EMG-recording. the experimenter also paced the inhalation tempo for the subject in all three phases of simulated or actual smoking. In the rapid-smoking condition. the inter-puff interval was IO s. while in the other tl\o conditions it was 30 s. The EMG-readings were taken between inhalations.
Analyses of variance were computed during cvcry phase in order to obtain diffcrcnccs in trends of muscle tonus between the conditions. The conditions wcrc analyzed and compared by pairs. No significant differences wcrc found between the conditions in Phase I (simulated smoking). In Phase 11 (actual smoking) divcrgcnt trends appcarcd between the conditions. Significant differences in trends bctwccn low and high nicotine levels (1. = 1.31. P < 0.05. d.f. = 7.35) and low and high with t-apic! smoking (I-’ = 7.73. P < 0.001. d.C = 7,;35) were obtained. There was no diffcrencc between high nicotine level and high with rapid smoking (F = 1.33. P < 0.30. d.f. = 7 ‘35). The results arc presented in Fig. 1. In Phase Ill (simulated smoking) the differences in trends lound in Phase II \verc now instead converging. The converging trend between low and high level with rapid
2 oo>
E
I 8Op
Simulated smoking
Smoking
Seconds
Simulated
Increase
of muscle
tonus
after tobacco
205
smoking
smoking (F = 2.95, P < 0.025, d.f. = 7/35) was significant. The other two pairs, high and low nicotine level (F = 1.22, P < 0.35, d.f. = 7/35) and high and high with rapid smoking (F = 1.20, P < 0.35, d.f. = 7/35) did not differ significantly from each other.
DISCUSSION
The results clearly indicate that tobacco consumption affects muscle tonus dose-dependently. Smoking a cigarette with a low nicotine level did not significantly affect the muscle tonus. However, a small but insignificant decrease of muscle tonus was observed (Fig. 1). Smoking a cigarette containing more nicotine increased the tonus, an effect which was further accentuated when the cigarette was smoked rapidly. The usual statement that smoking is relaxing was not supported by the results of this study. The feeling of relaxation can not be inferred from muscular tonus. Smoking rapidly or smoking a cigarette with a high level of nicotine seems. in fact, to have the opposite effect, i.e. increased muscle tonus. The inter-individual variation was so small that smokers’ reported relaxation can not be attributed to that factor. Smokers who seek relaxation, however, can perhaps decrease muscle tonus slightly by choosing cigarettes with low nicotine level and by inhaling more infrequently and shallowly. A plausible explanation of the paradox of smoking as a psychologically relaxing activity without measurable autonomic nervous signs of decreased activation is that of conditioning. The act of smoking frequently occurs in situations which naturally promote a decreased activation and relaxation, e.g. after meals, tea and coffee, after a task has been completed, during a break at work, etc. Gradually smoking in the presence of relaxation-promoting stimuli can in itself produce physiological relaxation, probably through both classical and operant conditioning. In the case of Webster’s (1964) paraplegic patient the testing situation could have been stressful and thus led to a higher experienced central arousal, which correlates positively with spasticity. Smoking a cigarette could thereby have acted as a conditioned anxiety reducing response and psychologically induce a more relaxed state. For an explanation of the difference in measurable EMG between the present study and Clark & Rand (1968) and Domino & von Baumgarten (1969) further research is needed. Some variables to be considered are tonic and phasic EMG, nicotine dosage, type of muscle, and measurement during muscle contraction vs muscle relaxation. In smoking withdrawal therapy, several clients who underwent rapid smoking (Lichtenstein et ul. 1973) responded with increased muscle tension, often to such a degree that they felt shaky and unsteady. Another interesting observation is that some very tense and hyperactive smokers have changed dramatically to much more relaxed and quiet individuals when they stopped smoking. Friends have regarded this change as a manifestation of a considerable “personality change”. However, such a change could also be attributed to the alleviation of both central and peripheral (high muscle tonus) activation. A justifiable conclusion is that the effects of smoking can no longer be regarded as simple and straightforward but rather as the result of highly complex behavior.
REFERENCES Brown, R. R., Relationship between evoked response changes and behavior An&s of the New York Academy ofScience. 1967, 142, lYC200. Clark, M. S. G. & Rand. M. J., Effect of tobacco smoke on knee-ierk of’ Pharmacology
Domino. New
Domino.
and Therapeutics, of’ &&,
E. F. & von Baumgarten.
Phurmacology
and Therapeutics,
small doses of nicotine.
reflex in man.
Europc,rr,t Jourj~trl
1968, 3, 294-302.
E. F., Electroencenhalonraohic York Academy
following
and iY67,
behavioral
arousal
of small
doses
of nicotine.
Ann&
of thr
142, 216-244.
A. M., Tobacco
cigarette
smoking
and patellar
reflex depression,
Clinical
1969, 10, 72-79.
Hickey. R. J. & Harner, E. B., Etiological and biochemical interactions and their relationships to smoking. In W. L. Dunn (Ed.). Smoking behavior: Motiws and irxwltirc,s. Washington: Whinston. 1973. Hutchmson, R. R. & Emeley, G. S., Avoidance, conditioned suppression and aggression response. In W. L. Dunn (Ed.), Smokirlg hehauior: Motiues and iwentices. Washington: Whinston 1973.
206
KARL-01 ov FAGCRSTII~N and K. GUNNAK GBTESTAM
Lichtenstein. E.. Harris, D. E.. Birchler. G. R., Wahl, J. M. & Schmal. D. P.. Comparison of rapid smoking. warm, smoky air. and attention placebo in the modification of smoking behavior. Joun~al c?f Co~~sulti~zq ajld Cliniul P.q~+olo~y, 1973. 40, 91-98. Tomkins. S. S., Psychological model for smoking behavior. Awrica~~ Jour~crl of’ Public Health und t/w Nutims Hculth. 1966. 56(12), 17 20. Webster. D. D.. The dynamic quantitation 01‘ spasticity with automated Integrals 01‘ passive motion reslstancc, Clirlicul Phtrmtrcokyy md Tlwnprutic~.s. 1964. 5. 9OC-908.
