Depression as a powerful discriminator between physically active and sedentary middle-aged men

JournalofPsychosomaticResearch, Printed in Great Britain.

DEPRESSION

AS A POWERFUL

PHYSICALLY

0022-3!+99/83/010069-08 $03.co/O Pergamon Press Ltd.

Vol. 27, No. 1, pp. 69-16, 1983.

ACTIVE

DISCRIMINATOR

AND SEDENTARY

BETWEEN

MIDDLE-AGED

MEN D. D. LOBSTEIN,** B. J. MOSBACHER,?and A. H. ISMAIL* (Received

23 February

1982; accepted

in revised form

13 June

1982)

Abstract-This study identifies the relative importance of psychological dimensions that discriminate between habitually physically active and sedentary men. The data support the notion that physical activity has psychological benefits. Subjects (N = 22) were normal, medically healthy middle-aged men (40-60 years of age). Data were collected on selected physiological (treadmill) and psychological (MMPI) variables and replicated within four months. The Student’s t-test and discriminant function analysis were used in the statistical analysis. Physically active men (n = 11) have lower depression (scale 2) and lower social introversion (scale 10) than the sedentary men (n = 11). The physically active men may exhibit MMPI scale differences in ‘neurotic’ tendencies from the sedentary men, but there is no apparent difference in scales suggestive of ‘psychotic’ tendencies. Depression (scale 2) is the most powerful discriminator between physically active and sedentary men, followed by hysteria (scale 3) and social introversion (scale 10). In conclusion, our data identify depression as the most important MMPI scale that discriminates between physically active and sedentary men. RESEARCH dealing with the psychological effects of regular aerobic exercise suggest that physical fitness training improves affective disposition, mood states, and selfconcept [ 1, 21; however, the relative importance of psychological variables in discriminating between physically active and sedentary men is not clear. The psychosomatic perspective may provide a framework for hypothesis generation and inference over causality, if controlled studies could focus on psychological variables known to discriminate between the physically active and the sedentary individual. The clinical scales of the MMPI adequately represent those psychological functions that appear to be affected by physical activity [3]. Although Naughton et al. [4] and Smith and Figetakis [5] observed no effects of physical fitness training on the MMPI profile, the former studied post-cardiac infarct patients and the latter studied isometric exercise in chronic schizophrenics. In contrast, Kavanagh et al. [6] reported that physical fitness training improved the scores on the MMPI depression scale in post-cardiac infarct patients, and Dodson and Mullens [7] observed that jogging significantly de&eased the scores on the hypochondriasis and psychasthenia scales of the MMPI in Veterans Administration Hospital in-patients with psychiatric disorders. Sharp and Reilly [8] may have noted MMPI score differences in college student males after an aerobic conditioning class, but the effects of physical activity on normal, medically healthy middle-aged men, as reflected on MMPI scales, appear to be unclear (e.g., see [l, 21). Folkins and Sime [3] recently critiqued the literature dealing with physical fitness training and mental health and suggested the following: (1) research in this area needs an integrated theoretical model; (2) studies *Department of Physical Education, Health and Recreation Studies, and *Department of Psychological Sciences, Purdue University, West Lafayette, IN47907, U.S.A. *Requests for reprints should be sent to Dr Lobstein. The principal author was supported in part by a David Ross Research Fellowship Grant, Purdue University. 69

D. D. LOBSTEIN, B. J. MOSBACHERand A. H. ISMW

70

must document physiological status; (3) a problem with Ismail’s research (e.g., see [9, 10, 111) is that many of his subjects were relatively physically fit before entering the fitness program; (4) no evidence supports the theory that ‘global’ changes on personality tests are caused by fitness training; and (5) future research efforts should focus on a ‘target’ variable expected to shift with training. The present authors suggest that selection of variables to be used in controlled studies must be done soundly, preferably with the knowledge of the relative import of each variable regarding physical activity and psychological function. Although reports (e.g., see [12, 131) indicate that variables such as anxiety, self-concept, depression, emotional stability and introversion appear to be affected by physical activity, few efforts have been directed towards understanding the degree of the multivariate interaction among those variables [9]. Understanding such relationships yields information regarding the relative importance of each variable. The purpose of the present report is to investigate the relative discriminating power of the MMPI clinical scales that differentiate between physically active and sedentary men. In so doing, the object is to select sound target variables that may be used in future controlled studies. METHODS Subjects (N = 22) were drawn from a pool of normal, medically healthy middle-aged men (40-60 years of age) who were self-selected apriorias physically active or sedentary. The physically active men (n = 11) had run for at least 20-60 min, three to six times per week for three to ten years at 75-85% of their maximal aerobic work capacity. Sedentary subjects (n = 11) had not performed regular aerobic exercise for the past three to ten years.* All collected data were replicated within four months to test for reliability. No significant ‘pre-post’ variability was detected. To approximate the true value, the average measurement was used for analysis. Physiological data were collected during the treadmill testing that consisted of exercise at a constant speed (1.6 m/se&) and increasing gradient (2”/2minh Lean body weight was estimated from weight and skinfold measurements [15]. Oxygen uptake was calculated using the true O7 percentage and the inspired air volume (STPD). The maximal oxygen uptake was predicted (v o2 max pred) by linear extrapolation of oxygen uptake with the expected maximal heart rate for the subject’s age [16]. The physical fitness score (PFS) was calculated by the regression equation developed from factor analysis by lsmail et al. [17]. Six criteria in the regression equation were found to have a high predictive value when assessing physical fitness (R2= 0.88, R = 0.94): submaximal exercise heart rate; -1.33 4.88 per cent lean body weight; 2.50 predicted maximal oxygen uptake/kg lean body weight; submaximal minute volume ventilation/kg body weight; -119.02 -1.36 resting diastolic blood pressure; 1.31 resting pulse pressure; 61.90 constant. Psychological data were collected using the Minnesota Multiphasic Personality Inventory (MMPI). As reviewed above, the clinical scales of the MMPI have been implicated in discriminating between physically active and sedentary men (e.g. see 12, 31). Univariate and multivariate statistical approaches were used in the analysis. In the univariate analysis, the means, standard errors, and Pearson product-moment correlation coefficients were calculated, and the two-tailed Student’s r-test was performed on the physically active vs sedentary group means for each variable. Those clinical scales of apparent significance in the univariate analysis were used in the multivariate analysis. The multivariate approach was used to investigate the interaction among the scales of interest and to indicate magnitude and direction in those scales that discriminate between the physically active and the sedentary groups. In the multivariate analysis, a disriminant function analysis [18] between active and sedentary group mean vectors was performed on the selected psychological variable set. *Informed 1141.

consent

was obtained

from the subjects

in accordance

with the Helsinki

Declaration

of 1975

Physical

activity

and depression

71

RESULTS

Descriptive and physiological data and the t-test results are presented in Table 1. Physically active men weighed about 20 kg less than sedentary men of the same age and height, yet the active men had 8% more lean body weight @ < 0.001). The t-test confirms beyond any reasonable doubt that the physically active men are aerobically trained, while the sedentary men have relatively little aerobic capacity (e.g., note the 20 beat/min difference in the resting heart rate and the 20 ml/(kg.min) difference in the VO, max pred P < 0.001). These differences in physical fitness are consistently associated with improved mental health [3]. Although psychological benefits are gained from the physical activity [2] the present study is not designed to indicate whether the psychological differences between the groups (e.g. in depression) are actually the cause or the effect of the physical differences. Rather, the purpose is to look at the relative difference of the MMPI scales that discriminate between physically active and sedentary men. Psychological data and the t-test are presented in Table 2. MMPI results indicate that the sedentary men are more depressed (scale 2) and introverted (scale 10) than the physically active men @ < 0.01). The clinical scales were K-corrected [19] and no TABLE 1.-DESCRIPTIVE AND PHYSIOLOGICAL DATA: MEANS, STANDARD ERRORS,AND I-TESTSBETWEEN PHYSICALLYACTIVE (n = 11) .~ND SEDENTARY (n = 11)GROUPS(Iv= 22) Variable

Age (years) active sedentary Weight (kg) active sedentary Height (cm) active sedentary Percent lean body weight active sedentary Resting heart rate (beats/min) active sedentary Resting systolic blood pressure (mm Hg) active sedentary Resting diastolic blood pressure (mm Hg) active sedentary voz max pred (ml/kg min) predicted maximal oxygen uptake active sedentary PFS (Ismail) physical fitness score [17] active sedentary *p < 0.05. tp < 0.001.

t-value

Mean

SE

48.82 49.45

2.19 2.88

-0.18

76.17 95.06

2.70 4.98

-3.33-f

178.91 180.30

2.43 1.90

-0.45

80.54 72.60

1.56 1.34

3.85t

56.18 79.55

2.46 3.44

-5.52-f

118.55 127.91

3.04 3.11

-2.16*

71.36 82.73

2.76 1.78

-3.46.f

51.02 28.40

1.69 2.40

7.71t

355.00 195.36

11.11 18.44

7.41-f

72

D. D. LOBSTEIN, B. J. MOSBACIIERand A. H. ISMAIL TABLE Z.-PSYCHOLOGICAL DATA: MMPI CLINICAL SCALE MEANS, STANDARD ERRORS AND I-TESTS BETWEEN PHYSICALLYACTIVE (n = 11) AND SEDENTARY (n = 11) GROUPS. DATA ARE EXPRESSEDIN T-SCORES [19]. Scale 1 Hypochondriasis active sedentary 2 Depression active sedentary 3 Hysteria active sedentary 4 Psychopathic deviate active sedentary 5 Masculinity-feminity active sedentary 6 Paranoia active sedentary I Psychasthenia active sedentary 8 Schizophrenia active sedentary 9 Hypomania active sedentary 10 Social introversion active sedentary

Mean

SE

t-value

50.09 52.45

1.83 1.51

-1.00

50.73 61.36

1.75 2.95

-3.10*

56.55 52.09

2.10 1.90

1.57

51.64 50.73

1.16 2.15

0.37

58.36 58.18

2.56 3.28

0.04

50.73 50.73

2.80 1.76

0.00

47.91 49.82

1.94 1.39

-0.80

51.27 49.09

2.08 1.90

0.78

54.91 52.36

2.50 3.00

0.65

48.18 57.82

2.13 2.24

-2.73;

*p < 0.01. TABLE 3.-DISCRIMINANT ANALYSIS BETWEEN PHYSICALLY ACTIVE AND SEDENTARYGROUP MEAN VECTORSFOR SELECTEDPSYCHOLOGICALVARIABLES (MMPI CLINICALSCALES,N = 22) Standardized

Variable Depression Hysteria Social introversion Eigenvalue 0.73 Per cent of grouped

coefficients

0.929 -0.596 0.002

(scale 2) (scale 3) (scale 10)

cases correctly

canonical

Wilks A 0.58 classified = 77.27.

2 10.15’

df 3

*p < 0.02.

significant difference was detected between the two groups on the MMPI validity scale means. The MMPI profiles for the physically active and sedentary group means are shown in Fig. 1. Clinically, the MMPI profile should be interpreted as a whole, rather than considering each scale independently [20, 211. Both the physically active and sedentary group profiles are within clinical limits for normal, mentally healthy

Physical

TO<

7

Tr

L

F

activity

2 K th-.5K cl

5 6 7 8 9 0 3 4 H” Pdt4KMT PO Pt+iKSctlKMhZKsi TorTc

453035-

73

and depression

50-

5555-

4550-

40-

40-

5050-

454035-

95 -

!5-

30-

30-

35-

15-

5550-

25--

45. 40.

zo-

15o-

3530-

IO35 -

4040_

to-25IO-

40-

3525-

70

60

20-

15-

IIO70100_10--

35-

40-

3530-

l 130-

75 _!20-

45-

6535-

3080

45-

40-

90 85 -

25 45-

m-

5-

5-

15-

5-

15 15-

IO-

l5-

IOIO-

,~_~.~~_.~~~~.

30.

IO-

O-

O-

25 -

o-

IOIO5-

T or 5c

FIG. 1.-The

) and sedentary MMPI profiles for physically active (errors. The profile grid is published by the Psychological

(- - - -) group means with standard Corporation [19].

middle-aged men, with no apparent differences in scales 1 (hypochondriasis), 4 6 (paranoia), 7 5 (masculinity-femininity), (psychopathic deviation), (psychasthenia), 8 (schizophrenia), or 9 (hypomania). However, several of the clinical scales that contribute to ‘neurotic’ dimensions, e.g., scales 2 (depression), 3 (hysteria), and 10 (social introversion), may discriminate between the physically active and sedentary men. These latter scales are tested for relative discriminating power in a subsequent analysis (Table 3). Several correlations are of particular interest. * Those significant (p < 0.05) correlations are between scale 2 (depression) and age (r = O&l), scale 2 and PO, mawnred (r = -0.52), and the K-scale and weight (r = -0.52). The discriminant function analysis presented in Table 3 selected relatively important psychological variables (MMPI clinical scales) that differentiate between physically active and sedentary groups. The most powerfully discriminating psycho*Data are available

upon request.

74

D. D. LOBSTEIN, B. J. MOSBACHER and A. H. ISMAIL

logical scales, in relative order of discriminating (hysteria), and 10 (social introversion).

power, are 2 (depression),

3

DISCUSSION

The present data support the notion that physical activity has psychological benefits (e.g., see [2, 3, 10, 111). As seen in the correlations, when physiological fitness deteriorates (increased chronological age) depression increases, and when physiological fitness is high (high Vol max nred) depression is low. In addition, low body weight is associated with high self-concept (K-scale). Young and Ismail [12] and Folkins et al. [13] suggested that self-confidence is a function of physical fitness. Low self-concept is a major component of affective disorders such as depression

WI. The univariate analysis indicated that middle-aged men who train aerobically are less depressed and more extroverted compared to sedentary men. The multivariate analysis indicated that scale 2 (depression) is the most statistically relevant dimension that powerfully discriminates between men who run and men who are sedentary. Scales 3 and 10 also discriminate between the two groups. Scale 3 may be a more powerful discriminator than scale 10 because the variance associated with scale 10 appears to be accounted for by scale 2, as evidenced by the significant correlation 0, < 0.01) between scale 2 and scale 10 (r = 0.59). The difference between the groups on scale 10 (extroversion) and the discriminating power of scale 3 (hysteria) may reflect narcissistic tendencies and enthusiasm exhibited by those who are habitually physically active. Such tendencies seem to be reflected by many observations regarding the psyche of the physically active individual [23]. No differences appear between physically active and sedentary groups on scales which purport to measure ‘psychotic’ tendencies (e.g. scales 6 and 8). These results were expected, given that the subjects were drawn from a normal population. However, Kostrubala [24] reported improved psychotic symptoms in case studies involving clinical patients. The present data are consistent with Tillman’s suggestion [25] that ‘basic’ personality structure (psychotic dimensions) does not change with improved physical fitness, but’mood’ variables (neurotic dimensions) appear to be altered with fitness status. Morgan et al. [26] reported that depression measured by the Zung Self-Rating depression Scale (SDS), and physical fitness were not correlated in normal adult males; however, clinically depressed men decreased SDS scores after fitness program training. Kavanagh et al. [6] reported significant improvement in the MMPI depression score, while other scales remained unchanged, in post-myocardial infarct patients who were in a regular running program. Brown et al. 1271and Greist et al. [28] suggest running as a treatment for moderate depression in clinically ‘normal’ individuals. Our data are consistent with those of Morgan et al., Kavanagh et al., Brown et al. and Greist et al. ; but, in addition, our data demonstrate that the depression scale of the MMPI is the most powerful discriminator between the physically active and sedentary groups, relative to the other MMPI scales. Depression is a complex dimension [29] and constructs are moving away from a unitary model [30]. Greist et al. [l] suggest hypotheses that might partly explain the beneficial effect running appears to have on depression: mastery

Physical

activity and depression

75

of skill and independence, patience and regular effort, capacity for change and selfacceptance, generalized feeling of competence, distraction from minor problems, altered state of consciousness, pleasure and satisfaction syndrome, and biochemical changes. In a review of the psychological benefits of physical activity, Morgan [2] concluded that relevant answers will soon be found at biochemical and neurophysiological levels. To explain the pleasure.and satisfaction syndrome at a biochemical level, for example, the hypothesis of Stein and Belluzzi [3 l] that endorphins mediate satisfaction and reward might be invoked. Reward dysfunction may be one etiological factor in affective disorders [3 11. The observation that acute bouts of exercise in well trained athletes seem to increase blood endorphin levels [32] appears to be consistent with the Stein and Belluzzi hypothesis. Perhaps regular physical activity maintains elevated central endorphin levels as well. Beta-endorphin given intravenously has anxiolytic and antidepressant effects in the clinical population [33]. We speculate that endorphin peptides in the normal population may increase selfconfidence and maintain emotional stability-noted psychological benefits of physical activity [ 12, 131. Despite the prevalence of the reductionist model, however, a teleological theoretical orientation must not be ruled out (e.g., see [34, 351). Ismail and Young [9, lo] characterized hierarchical and structural associations among many biochemical, physiological and psychological correlates and found that factor structures change following chronic exercise. To what degree the biochemical adaptations that occur with physical activity actually improve ‘neurotic’ dimensions will not be clear until controlled studies focus on identified ‘target’ dimensions [3]. Since our data identify depression (scale 2) as the most important target dimension, a breakdown of scale 2 into MMPI subscales [36] may be prudent, e.g. subjective depression, psychomotor retardation, physical malfunctioning, mental dullness and brooding. Identification of target subscales that discriminate between physically active and sedentary men should be of help in the next stage of research in the area of physical fitness and mental health. In conclusion, the present study supports the literature which indicates that physically active men are less depressed and more extroverted than sedentary men. In addition, the present study investigated the degree of interaction among selected MMPI clinical scales and our data identify depression as the most powerfully discriminating personality dimension between physically active and sedentary men. Acknowledgemenfs-The authors thank L. S. Verity, W. J. Chodzko-Zajko, Sothmann for their cooperation and help in collecting the data.

A. M. El-Naggar

and M. S.

REFERENCES 1. GREIST JH, KLEIN MH, EISCHENSRR, FARIS J, GURMAN AS, MORGAN WP. Running through your mind. J Psychosom Res 1978; 22: 259. 2. MORGAN WP. Psychological benefits of physical activity. In. Exercise, Health and Disease (Edited by NAGLE FJ, MONTAGE HJ). Springfield: C C Thomas, 1979. 3. FOLKINS CH, SIMEWE. Physical fitness training and mental health. Am Psychologist 1981; 36: 373. 4. NAUGHTON J, BRUHN JG, LATEG~LA MT. Effects of physical training on physiologic and behavioral characteristics of cardiac patients. Arch Phys Med Rehab 1968; 49: 131. 5. SMITH WC, FIGETAKIS N. Some effecs of isometric exercise on muscular strength in chronic schizophrenics. Am Corrective Ther J 1970; 24: 100.

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D. D. LOBSTEIN, B. J. MOSBACHERand A. H. ISMAIL

infarction. Can Med Assoc J 6. KAVANAGH T, SHEPHARD RJ, TUCK JA. Depression after myocardial 1975; 113: 23. I. DODSON LC, MULLENS WR. Some effects of jogging on psychiatric hospital patients. Am Corrective TherJ1969; 23: 130. of aerobic physical fitness to selected personality traits. J 8. SHARP MW, REILLEY RR. The relationship

Clin Psycho1 975; 31: 428. relationships between selected 9. ISMAILAH, YOUNG RJ. Effect of chronic exercise on the multivariate biochemical and personality variables. J Multivar Behav Res 1977; 12: 49. factors 10. ISMAIL AH, YOUNG RJ. Influence of physical fitness on second and third order personality using_orthogonal and oblique rotations. J C/in Psycho1 1976 ; 32: 268. between 11. YOUNG RJ, ISMAILAH. Ability of biochemical and personality variables in discriminating high and low physical fitness levels. J Psychosom Res 1978; 22: 193. differences of adult men before and after a physical fitness 12. YOUNG RJ, ISMAIL AH. Personality program. Res Q 1976; 47: 513. fitness as a function of physical fitness. Arch 13. FOLKINS CH, LYNCH S, GARDNER MM. Psychological

Phys Med Rehab 1972; 53: 503. 14. Policy statement regarding the use of human subjects and informed consent. Med Sci Sports Exercise 1980; 12: xi. estimation of body density and lean body weight in 15. WILMORE JH, BEHNKE AR. An anthropometric young men. J Appl Physiol 1969; 27: 25. 16. American College of Sports Medicine. Guidelines for Graded Exercise Testing and Exercise Prescriptron p. 16. Philadelphia: Lea & Febiger, 1976. AH, FALLS HB, MACLEOD DF. Development of a criterion for physical fitness tests from factor 17. 1s~ analysis results. J Appl Physiof 1965; 20: 991. 18. NIE NH, HULL CH, JENKINS JO, STEINBRENNER K, BENT DH. SPSS Stutisticuf Package for the Social Sciences, 2nd Ed. New York: McGraw-Hill, 1975. Corporation, 1967. 19. HATHAWAY SR, MCKINLEY JC. MMPZMunual. New York: The Psychological 20. DAHLSTROMWG, WELSH GS, DAHLSTROMLE. An MMPZ Handbook Vol I: Clinical Interpretation. Minneapolis: University of Minnesota Press, 1972. 21. DAHLSTROMWG, WELSH GS, DAHLSTROMLE. An MMPZ Handbook Vol ZZ:Research Applications. Minneapolis: University of Minnesota Press, 1975. Diagnostic and Statistical Manual of Mental Disorders. 3rd Ed. 22. American Psychiatric Association. 1981. IL: Human Kinetics Publishers, 23. SACKS MH, SACHS ML. Psychology of Running. Champaign, 1981. 1976. 24. KOSTRUBALAT. The Joy of Running. New York: Lippincott, between physical fitness and selected personality traits. Res Q 1965; 36: 25. TILLMAN K. Relationship 483. 26. MORGAN WP, ROBERTS JA, BRAND FR, FINERMAN AD. Psychological effect of chronic physical activity. Med Sci Sports 1971; 2, 213. 27. BROWN RS, RAMIREZ DE, TAUB JM. The prescription of exercise for depression. Physician Sports-

med 1978; 6: 35. 28. GREIST JH, KLEIN MH, EISCHENS RR, FARIS J, GURMAN AS, MORGAN WP. Running as treatment for depression. Comprehensive Psychiatry 1979; 20: 41. 29. AKISKALHS, MCKINNEY WT. Overview of recent research in depression. Arch Gen Psychiatry 1975; 32: 285. 30. CRAIGHEAD WE. Away from a unitary model of depression. Behav Ther 1980; 11: 122. hypothesis. 31. STEIN L, BELLUZZI JD. Brain endorphins and the sense of well-being: a psychobiological In The Endorphins: Advances in Biochemistry and Psychopharmacology (Edited by COSTA E, TRABUCCI M), 1978; 18: 299. 32. FRAIOLI F, MORETTI C, PAOLUCCI D, ALICICCO E, CRESCENZI F, FORTUNIO G. Physical exercise stimulates marked concomitant release of fl-endorphin and adrenocorticotropic hormone (ACTH) in peripheral blood in man. Experientia 1980; 36: 987. 33. USDIN E, BUNNEY WE, KLINE NS. (Editors). Endorphins in Mental Health Research. New York: Oxford University Press, 1979. in the psychology of the eighties. Can biochemistry eliminate addiction, 34. PEELE S. Reductionism mental illness, and pain? Am Psychologist 1981; 36: 807. 35. RYCHLAK JF. The Psychology of Rigorous Humanism. New York: Wiley, 1977. 36. GRAHAM JR. The MMPZ: a Practical Guide. New York: Oxford University Press, 1977.