Journal of Behavioral Medicine Vol 13, No.2, 1990

Psychological and Physical Reactions to Whirlpool Baths William N. Robiner, 1,2 Accepted for publication: July 21, 1989

Physical and psychological reactions to whirlpool baths were studied in a group of 40 healthy adult volunteers. Responses were measured after lO-min immersions in whirlpools under on and off conditions. Whirlpools and warm baths both induce increases in pulse and finger temperature, although a greater increase in finger temperature is associated with whirlpools. Both conditions produced increased feelings o f well-being and decreased state anxiety. Whirlpool immersion decreased stress reaction though the tub did not. Whirlpool immersion resulted in a slight decrease in D S M I11symptoms of anxiety. Immersion did not produce consistent significant changes in blood pressure, respiration rate, muscle tension, or pupil size. No changes emerged in anxiety, hostility, or depression on the Multiple Affect Adjective Checklist. Although whirlpools appear to be a popular form o f recreation, this study reveals limited significant incremental relaxation beyond the effects due to warm water alone. KEY WORDS: whirlpool; bath; psychological effects; physical effects; relaxation; water.

INTRODUCTION

Fascination with and attraction to water transcend cultural boundaries. Aside f r o m its essential physiologic role, water has been used for a IHealth Psychology Clinic and Department of Neurosurgery, University of Minnesota Hospital and Medical School, Minneapolis, Minnesota 55455. 2To whom correspondence should be addressed at Health PsychologyClinic, Box 731, University of Mirmesota Hospital & Clinic, Harvard Street at East River Road, Minneapolis, Minnesota 55455. 157 0160-7715/90/0400-0157506.00/0 9 1990 Plenum PublishingCorporation

158

Robiner

multitude of purposes including hydration, personal hygiene, religious rituals, and promotion of health. Ancient civilizations such as the Greeks and Egyptians had social customs surrounding soaking in luxurious pools. The early Roman Baths of Caracalla and Diocletian were luxurious and architecturally magnificent (Krizek, 1963), accommodating up to 18,000 people (Elder, 1975). The Japanese value "ofuros" for relaxation, for sociability and as a shared family activity. Water is used in religious rites of Native Americans (Kamenetz, 1963). Water has long been considered to have healing effects. Biblical references include miraculous cures, such as Naaman, who cleansed himself of leprosy by washing in the Jordan River (Krizek, 1963). Ponce de Leon, the Spanish explorer, sought the waters of a fountain of youth (Kamenetz, 1963). The Mayas may have used thermal springs for therapeutic purposes as early as 500 B.C. In North America, spas, springs, and bathing houses were popular in the eighteenth and nineteenth centuries. Healing powers were attributed to water in the popular press as early as 1847 in The N e w Englander and continue to be extolled (Kotzsch, 1988). Scientifically oriented periodicals such as the Water-Cure Journal and the New York WaterCure Reporter proliferated as early as the mid-nineteenth century (Kamenetz, 1963), with the development of hydrology, the study of the effects of water. In 1851, a medical school was established putatively based upon the curative powers of water (Weiss et al., 1967). During this century, health spas offering water treatments have experienced waxing and waning of popularity in the United States. Water has been prescribed as a treatment for a variety of ailments including arthritis, epilepsy, fever, general paresis, jaundice, meningitis, muscle problems, paralysis, peritonitis, pneumonia, psoriasis, tumors, typhoid fever, yellow fever, etc. (Kamenetz, 1963; Krizek, 1963). Modern Western medicine no longer champions water as a remedy for all of these ailments. However, warm water still is considered of benefit for problems such as arthritis, backache, wound care, burns, or exposure. In some settings, water is used to relieve orthopedic and neurological symptoms. Warm pools have been used therapeutically, as in Franklin D. Roosevelt's treatment for poliomyelitis. In the history of psychiatry, hydrotherapy played a role in the treatment of psychiatric and neurological disorders (Wright, 1932) including schizophrenia (May et al., 1964, 1965; Wright, 1932). Prolonged baths were once thought to be beneficial in managing schizophrenic excitement. Warm baths are commonly believed to relax muscles, dilate blood vessels, and facilitate blood circulation through such mechanisms as heat conduction, gentle massage, and softening of skin (Moor et al., 1964). Moist heat has been associated with an increase in leukocytes, neutrophils (Krusen,

Whirlpools

159

1941; cited by Moore et al., 1964), and white blood cells (McCutcheon, 1923, cited by Moore et al., 1964), suggesting that heat may play a role in mobilizing the immune system (Moore et al., 1964). The physiological effects of warm water lead doctors to advise caution in bathing when using alcohol and medications such as: anticoagulants, antihistamines, hypnotics, narcotics, stimulants, tranquilizers, vasoconstrictors, or vasodilators. Physiological experiments have involved warm water. In 1902, Muller (cited by Wright, 1932) concluded from a series of experiments that baths above 104~ raise blood pressure and pulse, with normal rates returning in 0.5 to 2 hrs, sometimes dipping below baseline rates. He found that baths involving mechanical excitation produced less enduring results. Winternitz (cited by Wright, 1932) found that hot water lowered blood pressure. In 1918, Kellogg (cited by Wright, 1932) also concluded that warm baths lower blood pressure by dilating surface vessels and inhibiting vasomotor centers, while lessening blood viscosity. Jetted tubs, such as whirlpool baths, mimic natural waves or currents. The pleasurable massaging or percussing effects are approximated by mechanically agitated water in tubs (Leroy, 1963). An early motor-driven whirlpool bath was described by Preiss in 1901. Whirlpools were used in France during World War I. By the end of World War II, physical therapy departments in many American hospitals contained whirlpool devices (Kamenetz, 1963). Similar devices, such as wooden hot tubs, emerged during the 1960s in California, leading to a renaissance in jetted water devices for recreational purposes. A range of tubs is now commercially available. Whirlpools require filling with hot water with each use. Hot tubs and spas contain heating elements which allow water to be recycled but necessitate chemical additives to prevent bacterial growth. A widespread assumption is that the circulating streams of water and air in jetted tubs promote relaxation. The popularity of jetted tubs is obvious: advertisements for jetted tubs appear regularly in newspapers, manufacturers exhibit devices at home and garden shows, health clubs entice prospective members to join to benefit from their effects, and realtors highlight them when selling properties. More than a half-million whirlpools and nearly a quarter-million spas were sold in the United States in 1987 according to estimates of the National Spa & Pool Institute and government (Davies, 1988). As hot tubs, whirlpools, and spas have become more popular, there has also been interest in the psychological and social effects of soaking in tubs (Elder, 1975; Silversmith, 1979). The present study was conducted to assess the physiological and psychological effects of whirlpools. The study was designed to test the hypothesis that whirlpools induce greater relaxation than immersion in warm quiescent water.

160

Robiner

METHODS Subjects Twenty male and twenty female white healthy (i.e., no history of cardiac problems) unpaid adults volunteered for participation in the study. Their mean age was 31.95 (SD = 5.1). All but four of the participants were college graduates; many held advanced degrees. Subjects were informed o f experimental hypotheses when they were debriefed after completing the study.

Procedures The research was conducted in a commercial showroom in Edina, Minnesota, on Sundays during a 4-month period, while the establishment was closed to the public. Advertising materials were hidden from view to reduce subject bias. Subjects immersed twice in a whirlpool. For one immersion the whirlpool motor was on (Whirlpool condition). For the other immersion, the motor was off (Tub condition). Subjects were randomly assigned to one of four conditions based on whirlpool (Pearl Oval V or Kohler Infinity) and o n / o f f sequence. Subjects wore bathing suits during their participation and additional garments (e.g., sweat suits) between immersions and while completing the dependent measures. Water temperature was chosen by each subject before the first immersion (M = 107.2~ SD = 1.85~ range = 103 to l l 0 ~ and held constant for the second immersion. Water level was held constant just below the level of the overflow drain. Subjects were left alone for 10 min during immersions. Subjects then towel dried thoroughly for a few minutes before resuming data collection. Physical measurements were followed by paper-and-pencil tasks after each immersion. After each series o f measurements, subjects immersed for the next experimental condition. At the end, subjects entered whirlpools (on) a third time and chose the length of their immersion. These last immersions ranged from 4 to 16 min (M = 6.70; SD = 3.33).

Measures Subjects completed a battery of physiological and psychological measures before the first immersion and after the first and second immersions. Physiological measures include pulse rate; finger temperature with a

Whirlpools

161

Cyborg P642 and thermistor sensors, systolic and diastolic blood pressure measured with an M.P.C. artery sphygmomanometer; respiration rate; electromyographic biofeedback measures of the frontalis muscle (i.e., forehead) using a Cyborg P303 EMG and Cyborg Q700 Data Accumulator with reusable silver-silver chloride sensors and Hewlett Packard redux paste for electrocardiography; and pupil size using a Lepore optic nerve test card. Psychological measures included the Well-Being and Stress Reaction scales from the Multidimensional Personality Questionnaire (Tellegen, 1982), the Self-Evaluation Questionnaire (Spielberger et al., 1983), the Multiple Affect Adjective Check List (Zuckerman et al., 1965), and a symptom checklist based on DSM III criteria for generalized anxiety disorder. Additional questionnaires were also completed at these times.

Analysis Univariate repeated-measures analyses of variance (ANOVA) were used to compare measurements for the preimmersion, whirlpool, and tub conditions. Newman-Keuls post hoc analyses were calculated when withinsubjects F tests met customary (p < .05) levels of significance. A paired t test compared pre-test and whirlpool conditions for DSM III anxiety symptoms (this measure was not obtained after the tub immersion). In most cases, analyses had 78 degrees of freedom, though when data were missing (< 0.1% of data), 76 degrees of freedom were available. Chi-squares were calculated to assess preferences between whirlpools and other activities associated with relaxation. Paired t tests evaluated sequence effects. Statistical analyses were conducted with Systat 3.2 and Data Desk versions 1.12 and 2.0.

RESULTS

Physiological Effects Table I reveals significant changes in pulse and finger temperature associated with both the whirlpool and the tub. There were significant (p < .001) increases in pulse rate due to the whirlpool (M = 13 beats/min; range = - 1 8 to +52)and tub (M = 10 beats/min; range = - 2 0 t o +32). Six subjects decreased and two exhibited no change for the whirlpool relative to baseline; two subjects decreased pulse and five showed no difference from baseline with the tub. The whirlpool and tub did not differ in their effects on pulse.

162

Robiner Table I. Physiological Parameters of Whirlpool and Tub Immersiona Preimmersion Measure

Postwhirlpool

Posttub

Mean

SD

Mean

SD

Mean

Pulse

66.70

8.2

79.70

14.1

76.83 11.75

22.31

.001"

Temperature of finger (~

82.40

6.39

87.89

3.82

86.04

4.20

20.73

.001"*

Diastolic blood pressure (mm Hg)

70.60

9.51

69.70

9.99

70.90

8.'J2

0.56

ns***

112.28 10.76 110.25 11.62

2.39

(.10)

Systolic blood pressure (ram Hg) Respiration (breaths/min)

110.80 9.88 17.10 2.57

SD

F

p

17.20

2.87

16.80

2.48

0.42

ns

EMG biofeedback

2.64

1.31

2.46

1.23

2.30

0.84

0.25

ns

Pupil diameter (mm)

3.65

0.82

3.51

0.84

3.57

0.80

1.28

ns

~Univariate repeated measures analysis of variance had 80 degrees of freedom except for pupil size (df = 76) due to missing data. *Newman-Keuls revealed that both whirlpool and tub conditions differed from the preimmersion condition at the p < .001 level but did not differ from each other. **Newman-Keuls revealed that both whirlpool and tub differed from the preimmersion condition at the p < .001 level; the whirlpool and tub differed at the p < .05 level. ***Follow-up analysis revealed one whirlpool brand which decreased diastolic blood pressure (19 < .05), though this appeared to be a statistical artifact based on preimmersion sample differences.

There were respective increases over baseline of 5.49 and 3.64~ in finger temperature for the whirlpool and tub conditions (/7 < .001). Whirlpools were associated with a greater 6o < .05) increase in finger temperature than warm water alone. This was the only significant physiological difference between the whirlpool and the tub conditions. Blood pressure effects were mild and variable. A trend 6o < .10) emerged f r o m whirlpools to increased systolic blood pressure with a mean of 1.5 m m Hg increase over baseline. Changes in systolic blood pressure ranged f r o m + 16 to - 8 m m Hg. Two individuals showed no change; 22 (55~ showed an increase in systolic blood pressure. No mean rise in systolic pressure was evident for the tub condition. Changes in systolic blood pressure for the tub ranged from + 10 to - 10 m m Hg. Six (15%) individuals showed identical baseline and tub immersion systolic blood pressure; 13 (33%) showed an increase. There were no significant decreases in diastolic blood pressure associated wkh the whirlpool or tub. Neither respiration rate, biofeedback E M G , nor pupil diameter revealed significant effects. Paired t tests revealed no sequence effects for any physiological measures.

3.56 3.07

6.59 2.80

M A A C L Hostility DSM III anxiety symptoms 1.68

7.05

11.83

5.45

29.85

7.53

Mean 19.58

2.18

2.81

4. I I

2.32

6.58

5.39

SD 3.52

Postwhirlpool

-

7.05

11.80

5.38

30.88

7.70

19.65

Mean

--

2.82

4.40

2.69

6.32

5.45

3.28

SD

Posttub F

--

0.77

0.01

0.05

30.88

3.20

3.38

2.14

tp,lrea

.04

ns

ns

ns

.001"**

.05**

.04*

aUnivariate repeated-measures analysis of variance h a d 80 degrees of freedom except for M A A C L measures (dr = 78) due to missing data. *Newman-Keuls revealed that b o t h whirlpool and tub differed f r o m the preimmersion condition at the p < .05 level but did n o t differ f r o m each other. **Newman-Keuls revealed that whirlpool differed from the preimmersion condition at the p < .05 level; other contrasts were n o t significant ***Newman-Keuls revealed that whirlpool and tub differed from the preimmersion condition at the p < .001 level but did not differ from each other.

5.09

5.51 11.67

M A A C L Anxiety

3.33

4.95 7.95

8.18 35.18

SD 3.73

Mean 19.08

Preimmersion

II. Psychological Parameters o f Whirlpool a n d Tub Immersion a

M A A C L Depression

State anxiety

Tellegen Well-being Tellegen Stress Reaction

Measure

Table

O

gl"

164

Robiner

Psychological Effects (Table II) Prior to immersion, subjects had mean ratings within the average range of anxiety, depression, and hostility scales of the MAACL (Zuckerman et aL, 1965). Initial ratings of State Anxiety (M = 35.18) ranged between the 48th and the 49th percentiles for normal adults. Scores decreased to the 44th percentile following the whirlpool and to the 45th percentile after the tub. The number of DSM III anxiety symptoms dropped (p < .05) from a baseline mean of 2.80 to 1.68 following the whirlpool. Subjects reported experiencing fewer (p < .001) anxiety symptoms following the whirlpool (M = 1.68) than they had during the past week (M = 8.0). The strongest psychological effects emerged with significant reductions in state anxiety for both the whirlpool and tub (p < .001) conditions relative to baseline. No significant differences emerged between the two conditions. Preimmersion state anxiety was somewhat lower (p < .07) than characteristic (trait) anxiety levels on the Self Evaluation Questionnaire, suggesting that subjects' anxiety levels at the outset of the protocol was below their norm. The experimental treatments did not result in significant lessening of anxiety, depression, or hostility on the Multiple Affect Adjective Check List (MAACL). There were mild increases in well-being (Tellegen, 1982) due to both the whirlpool and tub (p < .05), though not significant differences between the two conditions. On Tellegen's Stress Reaction scale, there was a mild mean decrease associated with the Whirlpool (M = 0.65; p < .05) but not for the tub. This was the only psychological variable on which the whirlpool elicited a more significant effect than the tub. When sequence effects were investigated for the psychological measures, state anxiety was significantly reduced after both (p < .001) immersions, with a trend toward less anxiety after the second immersion than the first (p < .07). Both the Well-Being (17 < .02) and the Stress Reaction (p < .03) scales revealed significantly more relaxation after the second immersion relative to the preimmersion, but no differences between the first and the second immersions or between the baseline and the first immersion. When subjects were asked to indicate their preferences, 34 (85o7o) preferred it on. As revealed in Table III, subjects were also asked to respond to a 5-point scale ranging from strong agreement (1) to strong disagreement (5) for several statements associated with relaxation. Following both types of immersion, subjects indicated feeling more warm, relaxed, calm, refreshed, unworried, and "like... floating" relative to baseline, and also agreed more with the statement "This is the life." On three additional items, significant changes were associated with whirlpool immersion but not tub immersion (i.e., "I wish I could feel like this always," "My limbs feel heavy," "It doesn't get any better than this"). On one item (i.e., "I am in no pain") significant

.97 1.01

2.88

3.98

3.30

3.05

I appreciate the calmness within me.

I feel like I am floating.

This is the life.

I fee! refreshed.

1.25

3.63 1.03 1.37 1.10

3.35

I feel tired.

I have all the energy I need. 1.13 1.04 1.04

2.05

3.28

1.80

2.00

3.48

I feel good.

This is the best I have ever felt.

I like who I am.

My problems are bearable.

I've never felt this good before. 99

1.13

1.02

2.88

I am in no pain.

3.60 2.25

It doesn't get any better than this.

1.02

3.13

My limbs feel heavy.

1.15

.88

I wish I could feel like this always.

now.

I have no real worries

3.10

1.25

3.45

All my muscles are relaxed. .90

1.08

3.38

I feel warm all over.

Item

SD

Mean

Preimmersion (P)

3.43

1.90

1.88

3.13

1.90

2.68

3.00

3.23 1.93

2.98

2.58

2.70

2.43

2.90

3.20

2.38

2.45

2.33

Mean

.87

.96

1.07

1.07

.96

1.10

1.11

1.00 1.44

1.25

1.06

1.18

.98

1.06

1.07

.84

1.13

1.07

SD

Postwhirlpool (W)

3.35

2.03

1.85

3.23

1.95

2.83

2.90

3.43 1.75

3.28

2.80

2.78

2.55

2.93

3.33

2.38

2.38

2.38

Mean

.89

1.03

.95

.99

.93

1.01

1.06

.98 1.21

.99

1.11

1.10

.99

.97

1.19

.77

.95

1.18

SD

P o s t t u b (T)

0.40

0.70

0.38

0.76

0.80

0.94

2.50

3.38 4.41

4.68

5.61

4.36

5.57

5.23

8.42

9.51

19.89

13.93

F

ns

ns

ns

ns

ns

ns

(.08)

.04 .02

.02

.005

.02

.005

.10

.001

.001

.001

.001

p
T

P>T

P>T

P>W

P>W

P>W

P>W; P>T

P>W; P>T

P>W; P>T

P>W; P>T

P>W;

P>W;

P>W; P>T

Newman-Keuls (p < .05) O

166

Robiner

differences emerged for the tub condition relative to preimmersion but not for the whirlpool condition. Beliefs about the effects of whirlpools were also inventoried. Eightythree percent (n = 33) thought that whirlpools provide mental health benefits. Fifty-five percent (n = 22) believe that whirlpools improve physiological health and 20% (n = 8) thought they might help people to live longer. Twenty percent (n = 8) believed that whirlpools were used mainly for pain management. One subject thought whirlpools were used mainly to enhance cleanliness. As an index of enjoyment associated with whirlpools, subjects compared whirlpools with other methods of relaxing (see Table IV). The directions for this questionnaire seemed to confuse some subjects, who began to complete items in one direction, changed their response set, and reversed their responses. All data were tabulated as written despite the concern about the validity of responses. Fewer items were completed on this survey than on any of the other dependent measures. The majority of participants reported preferences for whirlpools over a variety of other methods of relaxing, including alcohol (p < .05) and drug use 6O < .05) and watching television 6O < .05), as well as over baths 6o < .05) and showers 6o < .01). There were also more modest (nonsignificant) preferences for whirlpools over saunas or resting in bed. Most participants preferred massage 6O < .05) and sexual activity (/7 < .01) to the whirlpool. Trends emerged toward preferring reading and speaking with friends over the whirlpool. A majority described listening to music 6O < .01) as equally relaxing to taking a whirlpool. Among the limited number of subjects who identified prayer or worry beads as relaxation activities, a significant preference 6O < .05) emerged for the whirlpool over those activities.

DISCUSSION Physiological Effects

Physiological measures in the present study revealed limited changes due to immersion in tubs and whirlpools. The increased pulse rate associated with both experimental immersions likely is due primarily to heat-induced vasodilation, which produced compensatory increases in heart rate. The rise in pulse associated with immersions in warm water is likely a baroreceptor-mediated response. The increased pulse rate due to vasodilation from exposure to heat is consistent with Muller's earlier work. Since heart rates were not measured after a delay, it is not clear how long it may have taken to return to baseline or if below-baseline rates were ultimately

Whirlpools

167

achieved. It is possible that a pleasurable sense of relaxation is associated with the mild cardiovascular arousal produced by the heat. Both whirlpool and tub conditions produced significant increases in finger temperature. This physiological response paralleled responses to a questionnaire item in which feeling warmer after both whirlpools and tubs were described. These results may reflect either transfer of heat through conduction, or digit vasodilation due to sympathetic shutdown. Finger temperature was the only measure yielding significant differences between the two experimental conditions. Higher finger temperature was associated with whirlpools relative to tub immersions, even though the investigator endeavored to hold temperature constant. The flow of the water in whirlpools may result in more rapid infusion of heat into the body, as the skin is constantly in touch with warmer water. The effect may be heightened by the massaging stimulation of the water. These processes, in conjunction with potential autonomic effects, might explain how whirlpools facilitate healing, i.e., providing a higher skin temperature, bringing blood to the surface without actually being warmer than a tub. This result may have implications for treating hypothermia or frostbite with jetted tubs rather than conventional baths. Mean finger temperatures were relatively low, possibly reflecting excess air conditioning, especially preimmersion, and later cooling due to evaporation. Low readings, which are often construed as indicating anxiety, may have reflected significant physiological arousal at the beginning of the study, though other measures did not corroborate this interpretation. No unitary pattern in blood pressure effects was found. It had been anticipated that blood pressure might be increased as a result of vasodilation associated with heat, as in Muller's work, or eventually reduced relative to baseline, consistent with other investigators. Increased blood pressure would have been consistent with findings of an increased pulse rate. The lack of blood pressure changes may have reflected error variance inherent in measurement. The variation in blood pressure changes suggests that people, particularly those with relevant medical (e.g., cardiac) problems, be judicious when taking warm baths or jetted tubs. Monitoring of individual responses to immersion in warm water and consultation with medical personnel is recommended for people with histories of labile blood pressure or cardiac problems and when medications are being taken. Although the present study did not gauge blood pressure patterns during immersions, it may be advantageous to monitor changes during immersions for people at increased risk for blood pressure changes. A generalized decrease in muscle tension had been expected. The lack of significant decreases on EMG biofeedback monitoring of the frontalis muscle was surprising in not supporting the efficacy of warm water in re-

Activity preferable to whirlpool

9 10 5 3 3 10 8 8 7 12 8 8 8

3 10 15

Activity

Whirlpool preferable as modal response Alcoholic beverage Crafts Drug - nonprescription D r u g - - recreational D r u g - prescription b Listening to radio Resting in bed Sauna Sitting in comfortable chair Sports Television W a r m bath (non whirlpool) W a r m shower

Equal preference as m o d a l response Exercise- mild/moderate Fireplace Listening to music

5 17 19

5 7 3 4 0 6 12 13 11 8 7 7 4

Activity equal to whirlpool

1 7 3

21 15 15 17 17 20 15 15 17 19 19 20 23

Whirlpool preferable to activity

Table IV. Relaxation Preference Survey

0 2 0

1 6 12 14 17 0 1 1 0 3 1 0 0

Not applicable

8.00

4.48 5.14 7.26

4.17

5.00 9.80 9.80 3.33

4.80

x 2~

ns ns .01

.05 ns .05 .01 .01 (.10) ns ns .05 ns .05 .05 .01

p

Psychological and physical reactions to whirlpool baths.

Physical and psychological reactions to whirlpool baths were studied in a group of 40 healthy adult volunteers. Responses were measured after 10-min i...
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