Archives of Sexual Behavior, Vol. 5, No. 2, 1976
Orgasmic Frequency and Plasma Testosterone Levels in Normal Human Males Helena C. Kraemer, Ph.D., 1'2 Heather B. Becker, M.S., 1 H. Keith H. Brodie, M.D., 1 Charles H. Doering, Ph.D., 1 Rudolf H. Moos, Ph.D., 1 and David A. Hamburg, M.D. l
Twenty males participated in a 2-month study examining the relationship between 8 a.m. plasma testosterone levels and orgasmic frequency. Within subjects, higher levels o f testosterone are associated with periods o f sexual activity. Over subjects, however, the direction o f the relationship is reversed. Mean testosterone levels were higher for sexually less active individuals. KEY WORDS: testosterone; orgasmic frequency; sexual activity.
INTRODUCTION Investigators have long been interested in the relationship between androgen levels and sexual activity in the human male. Previous research reviewed by Luttge (1971), Rose (1972), Davidson and Levine (1972), and Cooper et al. (1972) has shown that testosterone administration to patients suffering from an androgen deficiency, such as occurs in primary hypogonadism, increases libido. The administration of cyproterone acetate, which primarily interferes with the action of testosterone, appears to reduce potency and libido in normal males (Morse et al., 1973; Cooper et aL, 1972) and in patients suffering from hypersexuality (Mothes et al., 1971). Several studies, in addition, examine the relationship between the endogenous level of testosterone and sexual activity. A self-study published anonymously (Anonymous, 1970) found that beard growth, taken as a measure of This research was supported by a grant from the Commonwealth Fund. t Laboratory of Stress and Conflict, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California 94305. 2Address reprint requests to Dr. KraemeL 125 © 1976 Plenum Publishing C o r p o r a t i o n , 227 West 17th Street, N e w Y o r k , N . Y . 10011. No part of this p u b l i c a t i o n m a y be r e p r o d u c e d , stored in a retrieval system~ or t r a n s m i t t e d , in a n y f o r m or b y a n y means, electronic, mechanical, p h o t o c o p y i n g , m i c r o f i l m i n g , recording, or o t h e r w i s e , w i t h o u t w r i t t e n permission of t h e publisher.
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androgen activity, was heaviest on the day when sexual intercourse was anticipated after a period of sexual abstinence. Once sexual activity was resumed, beard growth remained elevated only for 1 day. In another single-subject study (Fox et al., 1972), significant elevations were found in testosterone level during and immediately after sexual intercourse as compared to the level observed under resting conditions. This finding was not supported in a study of five subjects (Lee et al., 1974), where no significant change was reported between testosterone levels 23 and 24 hr before intercourse and 10 and 30 min, 1½, 24, and 48 hr after intercourse. A study of six subjects (Stearns et al., 1973) compared levels at 30-60 and 10-30 min before coitus and 10, 30, and 60 min after coitus and found no significant changes in testosterone level over that period. Finally, there is a related finding from a controlled study (Pirke et aI., 1974) which analyzed plasma testosterone levels before, during, and after the showing of a sexually explicit fdm. An increase in testosterone level was found, peaking at 60-90 min after the end of the film. Although the accumulated evidence does suggest that, for a given subject, elevation of testosterone level and increased sexual activity or excitement tend to be concomitant ("within-subject" relationship), the evidence is clearly not conclusive. Furthermore, there is no implication that if one subject exhibits a lower level of testosterone than another, the subject will tend to be less sexually active than the other ("between-subjects" relationship). We have not found any reports of a specific examination of the relationship between testosterone level and orgasmic activity between subjects. Raboch and St~rka (1972, 1973) measured plasma testosterone and coital activity in men 21-40 years old but apparently did not attempt to correlate the two measures among their subjects. Instead they analyzed the relationship between coital activity and testosterone level over groups where the group is defined either by the age of subject or by his clinical condition. Pirke et aI. (1974) presented the data for weekly orgasm frequency and mean plasma testosterone level for eight individual young men, and their data suggested that high orgasm frequency tended to be associated with low testosterone level, although the correlation was not significant. We report here the relationship between plasma testosterone levels and sexual activity on a longer time scale within normal subjects in the periods before and after testosterone determination. We have also examined the betweensubjects relationship between mean testosterone levels and mean orgasmic frequency in normal young male subjects.
MATERIALS AND METHODS
The subjects were 20 normal heterosexual males who were paid volunteers, aged 20-28 years (mean 23.4). Every subject had a regular sexual partner throughout the study. The Minnesota Multiphasic Personality Inventory was ad-
Orgasmic Frequency and Plasma Testosterone Levels in Males
127
ministered to the subjects as a screening device, and all fell within the range considered normal on all scales. Every other day between 8 and 9 a.m., a 10-ml blood sample was collected from each subject by venipuncture. During the course o f the 2-month study, the subjects carried out their normal daily activities. The subjects were asked to keep a simple record o f their sexual activity during this period, including the number o f times they had intercourse, masturbated, or performed any other sexual activity to achieve orgasm during the 24-hr period (from midnight to midnight). Plasma concentrations o f total testosterone were determined b y assaying each sample in duplicate by the modified technique o f August, Tkachuk, and Grumbach (August et al., 1969). This method involves extraction o f 0.3 ml of plasma, purification o f the extract b y two thin-layer chromatograms in series, and quantitation by competitive protein binding (saturation analysis) with late pregnancy plasma. Bound and free testosterone were separated b y precipitation with ammonium sulfate. The samples in each assay were coded and analyzed in random sequence. The recovery generally ranged between 70% and 80% (determined for each sample b y radiotracer). The accuracy was determined by use o f processed standards o f testosterone over the range of 0.5-2.0 ng; the average value found was 114% o f the amount added without blank correction. Blank values were 0.2-0.3 ng. The precision on the basis o f duplicate determinations Table I. Mean Testosterone Level Associated with Presence or Absence of Orgasmic Activity Orgasmic days
Subject
Number
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
15 14 21 13 15 4 20 23 22 23 6 16 14 10 12 8 10 20 1 19
Mean testosterone (ng/ml) 5.66 6.85 3.92 9.29 5.05 5.88 9.15 3.79 4.21 4.03 4.96 6.40 6.80 6.81 5.18 7.72 11.61 5.03 6.73 5.19
Anorgasmic daYs
Number
Mean testosterone (ng/ml)
4 5 6 12 3 15 5 0 3 4 17 3 8 17 12 11 15 3 10 1
5.12 7.19 3.90 8.57 3.95 5.34 8.01 3.88 3.50 4.93 5.58 6.67 7.64 4.86 5.20 10.97 4.96 8.14 4.42
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Table II. Mean and Standard Deviation of Testosterone Level for Each Subject and Proportion of Testosterone Determinations with Associated Orgasmic Activity
Subject
Number of observations
Overall mean testosterone level (ng/ml)
Standard deviation over days (ng/ml)
Proportion orgasmic days
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
19 19 27 25 18 19 25 23 25 27 23 19 22 27 24 19 25 23 11 20
5.55 6.94 3.92 8.94 4.87 5.45 8.92 3.79 4.18 3,95 4.94 6.27 6.76 7.33 5.02 6.26 11.23 5.02 8,01 5.15
1.17 1.56 0.804 1.45 1.34 0.771 1.55 1.06 0.870 0.859 0.904 1.99 1.17 1.21 0.920 2.61 1.73 0,736 0.928 1.33
0.789 0.737 0.778 0.520 0.833 0.211 0.800 1.000 0.880 0.852 0.261 0.842 0.636 0.370 0.500 0.421 0.400 0.870 0.091 0.950
averaged 13.5% (expressed as coefficient o f variation) for the individual subjects. Further details o f the assay have been described elsewhere (Doering et al., 1975a). F o r each subject, testosterone readings were separated according to whether there was or was not any orgasm reported in the period extending from midnight 32 hr before the time o f b l o o d drawing to midnight 16 hr after that time. The mean testosterone levels were computed for each subject over periods with no orgasmic activity and over periods with orgasmic activity (Table I). This is the basis for analysis o f the within-subject association between orgasmic activity and testosterone level. The overall mean testosterone level for each subject was computed, and the standard deviation o f levels over days o f observation. For each subject, the ratio o f testosterone determinations associated with reported orgasmic activity to the total number o f testosterone determinations was c o m p u t e d as a measure of orgasmic activity. These data (Table II) furnish t h e basis for analysis of the between-subjects association between orgasmic activity and testosterone level.
RESULTS There was considerable variation among the 20 subjects in average testosterone level, in within-subjects variability o f testosterone level, and in individual
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129
orgasmic activity (Table II). Mean plasma testosterone levels ranged from 3.79 ng/ml to 11.23 ng/ml, with a median of 5.5 ng/ml. The within-subjects standard deviations ranged from 0.74 ng/ml to 2.61 ng/ml, an indication of substantial individual differences in the stability of response over the 2-month study period (homogeneity of variance test: p < 0.001). The variability of a subject's testosterone level is correlated with his average level (Spearman rank correlation r s = + 0.603, p < 0.01) but not with his orgasmic frequency ( r s = - 0.056, N.S.). The measure of orgasmic activity ranged from 0.091 to 1.00, with a median of 0.76.
Within-Subjects Analysis There was one subject (No. 8) with no anorgasmic days. Two other subjects (Nos. 19 and 20) furnished insufficient information for adequate comparison of mean testosterone levels between orgasmic and anorgasmic periods. These three subjects were omitted from this analysis. Of the 17 remaining, 15 had a higher mean level of testosterone during periods of sexual activity than during periods of sexual inactivity (sign test: p < 0.005), indicating that the testosterone level for an individual tends to be elevated at times characterized by orgasmic activity. When there was sexual activity in the 48 hr period associated with the testosterone determination, it was possible to determine whether activity occurred in the 24 hr ending at midnight before the 8 a.m. blood withdrawal or in the 24 hr period ending at midnight after blood drawing. The mean testosterone level following a period in which one or more orgasms occurred was significantly higher than that in which none occurred (matched pairs t test: t l s = 1.78, p < 0.01, one-tailed test) (one subject was omitted because he reported no anorgasmic period preceding a blood drawing). There was no significant difference between mean testosterone level preceding a period in which one or more orgasms occurred and that preceding an anorgasmic period (matched pairs t test: tl 9 = 1.31, N.S.). Thus the elevation in testosterone level appears more likely a consequence than a precursor of sexual activity. There were 21 occasions (12 subjects)when there were three successive midnight-to-midnight periods of sexual abstinence with a blood withdraw~al after the first and third periods. The testosterone level following the first day Of abstinence was significantly higher than that following the third day of abstinence (matched pairs t test: t2o = 2.07,p < 0.05).
Between-Subjects Analysis From this positive association between orgasmic activity and testosterone level within subjects, however, no inference may be drawn as to the nature of the relationship of testosterone level and sexual activity over subjects. In fact,
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there is strong evidence that the correlation between testosterone level and sexual activity, positive within subjects, is negative over subjects. The Spearman rank correlation coefficient between the mean plasma testosterone levels and orgasmic frequency is - 0 . 5 1 4 (p < 0.05, two-tailed test). This indicates that the more sexually active the man, the lower his average testosterone level tends to be. The two subjects (Nos. 4 and 17) with highest testosterone levels had, respectively, 40.0% and 52.0% of blood drawings associated with reported orgasmic activity. For the two subjects (Nos. 3 and 8) with lowest testosterone levels, the comparable figures were 77.8% and 100%.
DISCUSSION
The structure of the relationship between sexual activity and testosterone cannot here be definitively ascertained. Our results are consistent with earlier results indicating that high testosterone levels are associated with high libido, or with sexual arousal, or with the hypothesis that sexual arousal produces an elevation in plasma testosterone level. If sexual stimulation produces an elevation in plasma testosterone level at the time of intercourse, as suggested by Fox et al. (1972) and Pirke et al. (1974), the higher testosterone level following a period of sexual activity found in the present study may indicate a persistence of that elevation for hours after intercourse. The same result is consistent, however, with the hypothesis that abstinence from sexual activity may produce a decrease in testosterone level. This hypothesis is supported by the finding that testosterone level following a third day of abstinence was lower than that following the first day of abstinence. More detailed studies of the sequential characteristics of testosterone and orgasmic activity are necessary, but at present it appears that sexual inactivity may be accompanied by a decrease of testosterone level as well as sexual activity by an increase. The reversal of the direction of the association between testosterone level and orgasmic frequency as these parameters differentiate subjects is surprising. This finding is, however, corroborated by a study (Pirke et al., 1974) which examined the data for eight subjects for weekly orgasm frequency and mean plasma testosterone level for four determinations at 15-min intervals. The rank correlation based on their reported data is -0.595, comparable in magnitude to the correlation found in the present study, but not statistically significant when based on so small a sample. One can but speculate as to the nature of the system governing testosterone-sexual activity interaction which could produce such results. Raboch and Stgrka (1972) believe that a certain minimum concentration of testosterone is required for adequate sexual activity in men but that a strict quantitative relation may not exist. In general, very little is known about threshold levels of androgens in individuals, either for action on peripheral target tissues or cen-
Orgasmic Frequency and Plasma Testosterone Levels in Males
131
trally to influence behavior. Thus there might exist, for example, a critical level of testosterone below which the subject is stimulated to sexual activity as the body's method of elevating testosterone level. Subjects whose level of testosterone is naturally low will more frequently fall below the critical level and will respond with more frequent sexual activity than those whose level of testosterone is naturally high. With such a system, the within-subjects correlation of testosterone and sexual activity will be positive, the between-subjects correlation will be negative. Previous research results suggest an association between testosterone level and tension, mental fatigue, and nervousness (Anonymous, 1970), and stress (Kreuz e t al., 1972). In related research we are finding relationships between testosterone levels and negative affect ratings as measured by the Multiple Affect Adjective Checklist self-rating scale (Doering e t al., 1974, 1975b). The nature of the stimulation process, therefore, may be by way of physiological or psychological concomitants of low testosterone level. The present study should stimulate further efforts to clarify the relationship between androgen levels and sexual behavior in man, not only by intensive study of testosterone and sexual activity but also by simultaneous consideration of other factors which undoubtedly play a role in the relationship.
REFERENCES Anonymous (1970). Effects of sexual activity on beard growth in man. Nature 226: 86%870. August, G. P., Tkachuk, M., and Grurnbach, M. (1969). Plasma testosterone-binding affinity and testosterone in umbilical cord plasma, late pregnancy, prepubertal children, and adults. J. Clin. Endoctrinol. 29: 891-899. Cooper, A. J., Ismail, A. A., Phanjoo, A. L., and Love, D. L. (1972). Antiandrogen (cyprotcrone acetate) therapy in deviant hypersexuality. Brit. J. Psychiat. 120: 59-63. Davidson, J. M., and Levine, S. (1972). Endocrine regulation of behavior. Ann. Rev. Physiol. 34: 375-408. Doering, C. H., Brodie, H. K. H., Kraemer, H. C., Becker, H., and Hamburg, D. A. (1974). Plasma testosterone levels and psychologic measures in men over a 2-month period. In Friedman, R. C., Richart, R. M., and Vande Wide, R. L. (eds.), Sex Differences in Behavior, Wiley, New York, pp. 413-431. Doering, C. H., Kraemer, H. C., Brodie, H. K. H., and Hamburg, D. A. (1975a). A cycle of plasma testosterone in the human male. J. Clin. Endocrinol. Metab. 40: 492-500. Doering, C. H., Brodie, H. K. H., Kraemer, H. C., Moos, R. H., Becket, H. B., and Hamburg, D. A. (1975b). Negative affect and plasma testosterone: A longitudinal human study. Psychosom. Med. 37: 484-491. Fox, C. A., Ismail, A. A. A., Love, D. N., Kirkham, K. E., and Loraine, J. A. (1972). Studies on the relationship between plasma testosterone levels and human sexual activity. 3.. Endocrinol. 52:51-58. Kreuz, L. E., Rose, R. M., and Jennings, J. R. (1972). Suppression of plasma testosterone levels and psychological stress. Arch. Gen. Psychiat. 26: 479-482. Lee, P. A., Jaffe, R. B., and Midgley, A. R., Jr. (1974). Lack of alteration of serum gonadotropins in men and women following sexual intercourse. Am. J. Obstet. Gynecol. 120: 985-987. Luttge, W. G. (1971). The role of gonadal hormones in the sexual behavior of the rhesus monkey and human: A literature survey. Arch. Sex. Behav. 1: 61.
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Morse, H. C., Leach, D. R., Rowley, M. J., and Heller, C. G. (1973). Effect of cyproterone acetate on sperm concentration, seminal fluid volume, testicular cytology and levels of plasma and urinary ICSH, FSH, and testosterone in normal men. J. Reprod. Fert. 32: 365-378. Mothes, C., Lehnert, J., Samimi, F., and Ufer, J. (1971). Klinische Priifung yon Cyproteronacetat bei Sexualdeviationen -Gesamtauswertung. In RaspS, G., and Bernhard, S. (eds.), Schering Symposium iiber Sexualdeviationen und ihre medikament6se Behandlung, Pergamon Press, New York, pp. 65-87. Pirke, K. M., Kockott, G., and Dittmar, F. (1974). Psychosexual stimulation and plasma testosterone in man. Arch. Sex. Behav. 3: 577-584. Raboch, J., and St~rka, L. (1972). Coital activity of men and the levels of plasmatic testosterone. J. Sex Res. 8: 219-224. Raboch, J., and St~rka, L. (1973). Reported coital activity of men and leyels of plasma testosterone. Arch. Sex. Behav. 2: 309-315. Rose, R. M. (1972). The psychological effects of androgens and estrogens - A review. In Shader, R. I. (ed.), Psychiatric Complications of Medical Drugs, Raven Press, New York, pp. 251-293. Stearns, E. L., Winter, J. S. D., and Faiman, C. (1973). Effects of coitus on gonadotropin, prolactin and sex steroid levels in man. J. Clin. Endocrinol. Metab. 37: 687-691.
Orgasmic Frequency and Plasma Testosterone Levels in Normal Human Males Helena C. Kraemer, Ph.D., 1'2 Heather B. Becker, M.S., 1 H. Keith H. Brodie, M.D., 1 Charles H. Doering, Ph.D., 1 Rudolf H. Moos, Ph.D., 1 and David A. Hamburg, M.D. l
Twenty males participated in a 2-month study examining the relationship between 8 a.m. plasma testosterone levels and orgasmic frequency. Within subjects, higher levels o f testosterone are associated with periods o f sexual activity. Over subjects, however, the direction o f the relationship is reversed. Mean testosterone levels were higher for sexually less active individuals. KEY WORDS: testosterone; orgasmic frequency; sexual activity.
INTRODUCTION Investigators have long been interested in the relationship between androgen levels and sexual activity in the human male. Previous research reviewed by Luttge (1971), Rose (1972), Davidson and Levine (1972), and Cooper et al. (1972) has shown that testosterone administration to patients suffering from an androgen deficiency, such as occurs in primary hypogonadism, increases libido. The administration of cyproterone acetate, which primarily interferes with the action of testosterone, appears to reduce potency and libido in normal males (Morse et al., 1973; Cooper et aL, 1972) and in patients suffering from hypersexuality (Mothes et al., 1971). Several studies, in addition, examine the relationship between the endogenous level of testosterone and sexual activity. A self-study published anonymously (Anonymous, 1970) found that beard growth, taken as a measure of This research was supported by a grant from the Commonwealth Fund. t Laboratory of Stress and Conflict, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California 94305. 2Address reprint requests to Dr. KraemeL 125 © 1976 Plenum Publishing C o r p o r a t i o n , 227 West 17th Street, N e w Y o r k , N . Y . 10011. No part of this p u b l i c a t i o n m a y be r e p r o d u c e d , stored in a retrieval system~ or t r a n s m i t t e d , in a n y f o r m or b y a n y means, electronic, mechanical, p h o t o c o p y i n g , m i c r o f i l m i n g , recording, or o t h e r w i s e , w i t h o u t w r i t t e n permission of t h e publisher.
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Kraemer, Becket, Brodie, Doering, Moos, and Hamburg
androgen activity, was heaviest on the day when sexual intercourse was anticipated after a period of sexual abstinence. Once sexual activity was resumed, beard growth remained elevated only for 1 day. In another single-subject study (Fox et al., 1972), significant elevations were found in testosterone level during and immediately after sexual intercourse as compared to the level observed under resting conditions. This finding was not supported in a study of five subjects (Lee et al., 1974), where no significant change was reported between testosterone levels 23 and 24 hr before intercourse and 10 and 30 min, 1½, 24, and 48 hr after intercourse. A study of six subjects (Stearns et al., 1973) compared levels at 30-60 and 10-30 min before coitus and 10, 30, and 60 min after coitus and found no significant changes in testosterone level over that period. Finally, there is a related finding from a controlled study (Pirke et aI., 1974) which analyzed plasma testosterone levels before, during, and after the showing of a sexually explicit fdm. An increase in testosterone level was found, peaking at 60-90 min after the end of the film. Although the accumulated evidence does suggest that, for a given subject, elevation of testosterone level and increased sexual activity or excitement tend to be concomitant ("within-subject" relationship), the evidence is clearly not conclusive. Furthermore, there is no implication that if one subject exhibits a lower level of testosterone than another, the subject will tend to be less sexually active than the other ("between-subjects" relationship). We have not found any reports of a specific examination of the relationship between testosterone level and orgasmic activity between subjects. Raboch and St~rka (1972, 1973) measured plasma testosterone and coital activity in men 21-40 years old but apparently did not attempt to correlate the two measures among their subjects. Instead they analyzed the relationship between coital activity and testosterone level over groups where the group is defined either by the age of subject or by his clinical condition. Pirke et aI. (1974) presented the data for weekly orgasm frequency and mean plasma testosterone level for eight individual young men, and their data suggested that high orgasm frequency tended to be associated with low testosterone level, although the correlation was not significant. We report here the relationship between plasma testosterone levels and sexual activity on a longer time scale within normal subjects in the periods before and after testosterone determination. We have also examined the betweensubjects relationship between mean testosterone levels and mean orgasmic frequency in normal young male subjects.
MATERIALS AND METHODS
The subjects were 20 normal heterosexual males who were paid volunteers, aged 20-28 years (mean 23.4). Every subject had a regular sexual partner throughout the study. The Minnesota Multiphasic Personality Inventory was ad-
Orgasmic Frequency and Plasma Testosterone Levels in Males
127
ministered to the subjects as a screening device, and all fell within the range considered normal on all scales. Every other day between 8 and 9 a.m., a 10-ml blood sample was collected from each subject by venipuncture. During the course o f the 2-month study, the subjects carried out their normal daily activities. The subjects were asked to keep a simple record o f their sexual activity during this period, including the number o f times they had intercourse, masturbated, or performed any other sexual activity to achieve orgasm during the 24-hr period (from midnight to midnight). Plasma concentrations o f total testosterone were determined b y assaying each sample in duplicate by the modified technique o f August, Tkachuk, and Grumbach (August et al., 1969). This method involves extraction o f 0.3 ml of plasma, purification o f the extract b y two thin-layer chromatograms in series, and quantitation by competitive protein binding (saturation analysis) with late pregnancy plasma. Bound and free testosterone were separated b y precipitation with ammonium sulfate. The samples in each assay were coded and analyzed in random sequence. The recovery generally ranged between 70% and 80% (determined for each sample b y radiotracer). The accuracy was determined by use o f processed standards o f testosterone over the range of 0.5-2.0 ng; the average value found was 114% o f the amount added without blank correction. Blank values were 0.2-0.3 ng. The precision on the basis o f duplicate determinations Table I. Mean Testosterone Level Associated with Presence or Absence of Orgasmic Activity Orgasmic days
Subject
Number
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
15 14 21 13 15 4 20 23 22 23 6 16 14 10 12 8 10 20 1 19
Mean testosterone (ng/ml) 5.66 6.85 3.92 9.29 5.05 5.88 9.15 3.79 4.21 4.03 4.96 6.40 6.80 6.81 5.18 7.72 11.61 5.03 6.73 5.19
Anorgasmic daYs
Number
Mean testosterone (ng/ml)
4 5 6 12 3 15 5 0 3 4 17 3 8 17 12 11 15 3 10 1
5.12 7.19 3.90 8.57 3.95 5.34 8.01 3.88 3.50 4.93 5.58 6.67 7.64 4.86 5.20 10.97 4.96 8.14 4.42
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Table II. Mean and Standard Deviation of Testosterone Level for Each Subject and Proportion of Testosterone Determinations with Associated Orgasmic Activity
Subject
Number of observations
Overall mean testosterone level (ng/ml)
Standard deviation over days (ng/ml)
Proportion orgasmic days
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
19 19 27 25 18 19 25 23 25 27 23 19 22 27 24 19 25 23 11 20
5.55 6.94 3.92 8.94 4.87 5.45 8.92 3.79 4.18 3,95 4.94 6.27 6.76 7.33 5.02 6.26 11.23 5.02 8,01 5.15
1.17 1.56 0.804 1.45 1.34 0.771 1.55 1.06 0.870 0.859 0.904 1.99 1.17 1.21 0.920 2.61 1.73 0,736 0.928 1.33
0.789 0.737 0.778 0.520 0.833 0.211 0.800 1.000 0.880 0.852 0.261 0.842 0.636 0.370 0.500 0.421 0.400 0.870 0.091 0.950
averaged 13.5% (expressed as coefficient o f variation) for the individual subjects. Further details o f the assay have been described elsewhere (Doering et al., 1975a). F o r each subject, testosterone readings were separated according to whether there was or was not any orgasm reported in the period extending from midnight 32 hr before the time o f b l o o d drawing to midnight 16 hr after that time. The mean testosterone levels were computed for each subject over periods with no orgasmic activity and over periods with orgasmic activity (Table I). This is the basis for analysis o f the within-subject association between orgasmic activity and testosterone level. The overall mean testosterone level for each subject was computed, and the standard deviation o f levels over days o f observation. For each subject, the ratio o f testosterone determinations associated with reported orgasmic activity to the total number o f testosterone determinations was c o m p u t e d as a measure of orgasmic activity. These data (Table II) furnish t h e basis for analysis of the between-subjects association between orgasmic activity and testosterone level.
RESULTS There was considerable variation among the 20 subjects in average testosterone level, in within-subjects variability o f testosterone level, and in individual
Orgasmic Frequency and Plasma Testosterone Levels in Males
129
orgasmic activity (Table II). Mean plasma testosterone levels ranged from 3.79 ng/ml to 11.23 ng/ml, with a median of 5.5 ng/ml. The within-subjects standard deviations ranged from 0.74 ng/ml to 2.61 ng/ml, an indication of substantial individual differences in the stability of response over the 2-month study period (homogeneity of variance test: p < 0.001). The variability of a subject's testosterone level is correlated with his average level (Spearman rank correlation r s = + 0.603, p < 0.01) but not with his orgasmic frequency ( r s = - 0.056, N.S.). The measure of orgasmic activity ranged from 0.091 to 1.00, with a median of 0.76.
Within-Subjects Analysis There was one subject (No. 8) with no anorgasmic days. Two other subjects (Nos. 19 and 20) furnished insufficient information for adequate comparison of mean testosterone levels between orgasmic and anorgasmic periods. These three subjects were omitted from this analysis. Of the 17 remaining, 15 had a higher mean level of testosterone during periods of sexual activity than during periods of sexual inactivity (sign test: p < 0.005), indicating that the testosterone level for an individual tends to be elevated at times characterized by orgasmic activity. When there was sexual activity in the 48 hr period associated with the testosterone determination, it was possible to determine whether activity occurred in the 24 hr ending at midnight before the 8 a.m. blood withdrawal or in the 24 hr period ending at midnight after blood drawing. The mean testosterone level following a period in which one or more orgasms occurred was significantly higher than that in which none occurred (matched pairs t test: t l s = 1.78, p < 0.01, one-tailed test) (one subject was omitted because he reported no anorgasmic period preceding a blood drawing). There was no significant difference between mean testosterone level preceding a period in which one or more orgasms occurred and that preceding an anorgasmic period (matched pairs t test: tl 9 = 1.31, N.S.). Thus the elevation in testosterone level appears more likely a consequence than a precursor of sexual activity. There were 21 occasions (12 subjects)when there were three successive midnight-to-midnight periods of sexual abstinence with a blood withdraw~al after the first and third periods. The testosterone level following the first day Of abstinence was significantly higher than that following the third day of abstinence (matched pairs t test: t2o = 2.07,p < 0.05).
Between-Subjects Analysis From this positive association between orgasmic activity and testosterone level within subjects, however, no inference may be drawn as to the nature of the relationship of testosterone level and sexual activity over subjects. In fact,
130
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there is strong evidence that the correlation between testosterone level and sexual activity, positive within subjects, is negative over subjects. The Spearman rank correlation coefficient between the mean plasma testosterone levels and orgasmic frequency is - 0 . 5 1 4 (p < 0.05, two-tailed test). This indicates that the more sexually active the man, the lower his average testosterone level tends to be. The two subjects (Nos. 4 and 17) with highest testosterone levels had, respectively, 40.0% and 52.0% of blood drawings associated with reported orgasmic activity. For the two subjects (Nos. 3 and 8) with lowest testosterone levels, the comparable figures were 77.8% and 100%.
DISCUSSION
The structure of the relationship between sexual activity and testosterone cannot here be definitively ascertained. Our results are consistent with earlier results indicating that high testosterone levels are associated with high libido, or with sexual arousal, or with the hypothesis that sexual arousal produces an elevation in plasma testosterone level. If sexual stimulation produces an elevation in plasma testosterone level at the time of intercourse, as suggested by Fox et al. (1972) and Pirke et al. (1974), the higher testosterone level following a period of sexual activity found in the present study may indicate a persistence of that elevation for hours after intercourse. The same result is consistent, however, with the hypothesis that abstinence from sexual activity may produce a decrease in testosterone level. This hypothesis is supported by the finding that testosterone level following a third day of abstinence was lower than that following the first day of abstinence. More detailed studies of the sequential characteristics of testosterone and orgasmic activity are necessary, but at present it appears that sexual inactivity may be accompanied by a decrease of testosterone level as well as sexual activity by an increase. The reversal of the direction of the association between testosterone level and orgasmic frequency as these parameters differentiate subjects is surprising. This finding is, however, corroborated by a study (Pirke et al., 1974) which examined the data for eight subjects for weekly orgasm frequency and mean plasma testosterone level for four determinations at 15-min intervals. The rank correlation based on their reported data is -0.595, comparable in magnitude to the correlation found in the present study, but not statistically significant when based on so small a sample. One can but speculate as to the nature of the system governing testosterone-sexual activity interaction which could produce such results. Raboch and Stgrka (1972) believe that a certain minimum concentration of testosterone is required for adequate sexual activity in men but that a strict quantitative relation may not exist. In general, very little is known about threshold levels of androgens in individuals, either for action on peripheral target tissues or cen-
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trally to influence behavior. Thus there might exist, for example, a critical level of testosterone below which the subject is stimulated to sexual activity as the body's method of elevating testosterone level. Subjects whose level of testosterone is naturally low will more frequently fall below the critical level and will respond with more frequent sexual activity than those whose level of testosterone is naturally high. With such a system, the within-subjects correlation of testosterone and sexual activity will be positive, the between-subjects correlation will be negative. Previous research results suggest an association between testosterone level and tension, mental fatigue, and nervousness (Anonymous, 1970), and stress (Kreuz e t al., 1972). In related research we are finding relationships between testosterone levels and negative affect ratings as measured by the Multiple Affect Adjective Checklist self-rating scale (Doering e t al., 1974, 1975b). The nature of the stimulation process, therefore, may be by way of physiological or psychological concomitants of low testosterone level. The present study should stimulate further efforts to clarify the relationship between androgen levels and sexual behavior in man, not only by intensive study of testosterone and sexual activity but also by simultaneous consideration of other factors which undoubtedly play a role in the relationship.
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