31

Intern. J. Neuroscience, 114:31–45, 2004
Copyright 

 Taylor & Francis Inc.

ISSN: 0020-7454 / 1543-5245 online
DOI: 10.1080/00207450490249446

MASSAGE THERAPY OF MODERATE

AND LIGHT PRESSURE AND VIBRATOR

EFFECTS ON EEG AND HEART RATE

MIGUEL A. DIEGO
TIFFANY FIELD
CHRIS SANDERS
MARIA HERNANDEZ-REIF

University of Miami School of Medicine
Miami, Florida, USA

Three types of commonly used massage therapy techniques were as-
sessed in a sample of 36 healthy adults, randomly assigned to: (1)
moderate massage, (2) light massage, or (3) vibratory stimulation group
(n = 12 per group). Changes in anxiety and stress were assessed, and
EEG and EKG were recorded. Anxiety scores decreased for all groups,
but the moderate pressure massage group reported the greatest de-
crease in stress. The moderate massage group also experienced a de-
crease in heart rate and EEG changes including an increase in delta
and a decrease in alpha and beta activity, suggesting a relaxation re-
sponse. Finally, this group showed increased positive affect, as indi-
cated by a shift toward left frontal EEG activation. The light massage
group showed increased arousal, as indicated by decreased delta and
increased deta activity and increased heart rate. The vibratory stimula-
tion group also showed increased arousal, as indicated by increased
heart rate and increased theta, alpha, and beta activity.

Keywords

EEG, EKG, massage, stimulation, touch

Received 12 May 2003.
We would like to thank the mothers who participated in this study. This research was sup-

ported by an NIMH Research Scientist Award (#MH00331) to Tiffany Field, PhD, and funding
from Johnson and Johnson.

Address correspondence to Tiffany Field, PhD, Touch Research Institutes, University of

Miami School of Medicine, Department of Pediatrics (D-820), P.O. Box 016820, Miami, FL 33101,
USA. E-mail: tfield@med.miami.edu

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32

M. A. Diego et al.

Massage therapy, one of the oldest treatment modalities, has been
re-emerging as one of the most popular forms of alternative therapy.
Despite its long history, controlled studies have only recently been
conducted to assess the biochemical, physiological, cognitive, and
emotional effects of massage therapy (Field, 1998), and no studies
have yet evaluated different pressure massage therapy and vibrator
effects.

Recent studies indicate that massage therapy can: (1) decrease

anxiety levels (Field, Morrow, Valdeon, Larson, Kuhn, & Shanberg,
1992; Field, Ironson, Pickens, Nawrocki, Goncalves, & Burman,
1996); (2) decrease depressed mood (Field, Seligman, Scafidi, &
Shanberg, 1997; Jones & Field, 1999); (3) increase alertness as
suggested by EEG patterns of alertness (Field et al., 1996); (4) en-
hance cognitive performance as suggested by increased perform-
ance on math computations (Field et al., 1996); and (5) alter bio-
chemical (catecholamines, serotonin, and cortisol) levels in a positive
direction (Hernandez-Reif, Dieter, Field, Swerdlow, & Diego, 1998;
Kuhn, Shanberg, Field, Symanski, Zimmerman, Scafidi, & Roberts,
1991).

Only three studies have examined the effects of massage therapy

on EEG activity (Field et al., 1996; Jodo, Yamada, Hatayama, Abe, &
Maruyama, 1998, Jones & Field, 1999). In one study, participants
receiving

 

facial massage therapy exhibited decreased alpha and beta

power, an EEG pattern that may reflect attention and alertness (Klimesch,
Doppelmayer, Russegger, Pachinger, & Shwaiger, 1998; Shagass,
1972; Nunez, 2000). Similarly, adults receiving 15 min of massage
therapy showed a pattern of increased delta power and decreased
alpha and beta (Field et al., 1996), suggesting increased relaxation
and alertness (Niedermeyer, 1982). Another study examining the
effects of massage therapy on EEG showed that following 15 min of
massage therapy, depressed adolescents showed less right frontal
EEG asymmetry (Jones & Field, 1999). Right frontal EEG asymme-
try has been related to negative mood and affect and may be a marker
for depression (Davidson, 2000).

Few controlled studies have evaluated different pressure or

different massage therapy techniques. One study that assessed
blood flow in response to deep pressure stroking versus percussion
movements revealed that only the percussion movements increased
blood flow (Hovind & Nielsen, 1974). In another study assessing

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Moderate, Light, and Vibratory Massage

33

alpha motor neuron excitability, deep pressure massage reduced H-
reflex excitability, whereas light fingertip pressure did not (Sullivan,
Williams, Seaborne, & Morelli, 1991). This finding supports data
from other studies that have shown that deep pressure stroking pro-
duces significant physiological and psychological effects, whereas
light pressure stroking does not. For example, one study assessing
limb blood flow by a Doppler Ultrasound failed to show any effects
of light pressure stroking (Shoemaker, Tiidus, & Mader, 1997). In
contrast, a study assessing the effects of deep pressure massage
found an increased range of motion and changes in electroneuro-
myograpy (ENMG) following treatment (McKechnie, Wilson, Watson,
& Scott, 1983). In this pilot study, mean heart rate (BPM) and
EMG activity decreased, while skin resistance (SRL) increased in
response to connective tissue massage (deep pressure). Vibratory
stimulation has been shown to enhance relaxation and decrease pain
in adults (Lundeberg, 1984; Ottoson, Ekblom, & Hansson, 1981).

The present study assessed the physiological and psychological

effects of three different massage therapy techniques, including light
pressure and deep pressure massage provided by hands and vibra-
tory stimulation provided by a mechanical massager (Thumper Mini
Pro, Model #NAOOP, Worldwide Patents). The physiological ef-
fects of the three massage conditions were assessed by monitoring
heart rate and EEG data from each participant and also assessed
anxiety and stress on self-report scales.

As in previous studies, moderate pressure stimulation was ex-

pected to produce decreased heart rate, negative affect, and anxiety.
EEG for this condition was expected to reflect increased delta and
decreased alpha and beta power, suggesting a pattern of relaxation
and alertness and a shift toward greater left frontal EEG asymmetry,
suggesting greater positive affect. No specific effects were hypoth-
esized for the low pressure or the vibratory stimulation groups.

METHOD

Participants

The sample included 36 faculty and staff members of a large urban
medical school (58% females, 42% males, M age = 28). They were

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34

M. A. Diego et al.

middle- to upper-middle socioeconomic status (M = 2.58 on the
Hollingshead), and were 58% Caucasian, 25% Hispanic, 9% African
American, and 8% Asian. The participants were randomly assigned
to a light pressure touch, moderate pressure touch, or vibratory stim-
ulation condition.

Assessment Procedures

The procedure was conducted in the following order: (1) an EEG
cap was positioned on the participants’ head; (2) EKG electrodes
were placed along the participants’ arms; (3) participants completed
the session baseline measures, including the demographic question-
naire
, the State Anxiety Inventory (STAI; Spielberger, Gorsuch, &
Luschene, 1970), the visual analogue stress/relaxation scale, and
the  Touch Aversion Questionnaire; (4) a 3-min baseline, followed
by the 10-min massage was given, and a 3-min post session, during
which EEG and EKG were continuously recorded; (5) followed by
the  STAI and the visual analogue stress/relaxation scale.

EEG Procedures

EEG was recorded for 3-min periods prior to 10 min during and
3 min after the massage, with the subjects’ eyes closed. The EEG
was recorded using a lycra stretchable cap (Electro-Cap, Inc.), posi-
tioned on the participant’s head using the standard 10–20 system.
Electrode gel was inserted into the midfrontal (F3 & F4), central
(C3 & C4), anterior temporal (T3 & T4), and parietal (P3 & P4)
sites and referenced to the vertex (Cz) during recording. Imped-
ances were brought below 5K ohms. The EEG signals were ampli-
fied using Biopac EEG100B amplifiers. The output from the ampli-
fiers was directed to a Dell Inspiron 7000 laptop computer fitted
with the Biopac MP100 Acquisition System. The signal was sampled
at a rate of 512 samples per second, streamed onto the computer
screen, and then saved to a hard drive.

EEG was then computed off-line to derive a computer-averaged

site reference, and then it was edited for artifact, using software
designed by James Long, Inc. The artifact-free data were spectrally
analyzed using a discrete Fourier transform with a Hanning window,

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Moderate, Light, and Vibratory Massage

35

with 50% overlap to yield power values (in uV

2

) for the following

frequency bands: 1–4 Hz (delta); 5–7 Hz (theta); 8–12 Hz (alpha);
13–20 Hz (low beta) and 21–30 Hz (high beta). These values were
then log transformed to normalize the data, and asymmetry scores
were then computed. Asymmetry scores represent the difference of
mean log power density scores in a right hemisphere site and its
homologous left hemisphere site (lnRight-lnLeft). To be con-sistent
with a previous study (Field et al., 1996) and to have an adequate
variable to participants’ ratio, only frontal EEG values were ana-
lyzed.

EKG Procedures

EKG was obtained for 3 min—pre, during, and post massage—by
placing 3 EKG electrodes in a standard configuration along the par-
ticipants’ inner arms. The EKG signals were amplified using a Biopac
EKG100B amplifier. The output from the amplifiers was directed to
a Dell Inspiron 7000 laptop computer fitted with the Biopac MP100
Acquisition System. The signal was sampled at a rate of 512 samples
per second and streamed onto the computer screen, and then saved
to a hard drive. EKG data were then edited for artifact, and beats-
per-minute (BPM) were computed off-line using AcqKnowledge soft-
ware.

Touch Aversion Questionnaire

The Touch Aversion Questionnaire is a 24-item questionnaire that
measures sensitivity to touch, with 1 representing “no,” 2 “a little,”
and 3 “a lot.” Characteristic items include “Do fuzzy shirts bother
you?” and “Does it bother you to have your face touched?” A sum-
mary score is obtained by adding the weight of each item. Higher
scores indicate greater touch aversion.

Pre-Post Self-Report Measures

The following measures were used to assess the immediate effects
of the different types of massage. The STAI (Spielberger et al.,
1970) is a 20-item scale that measures transitory anxiety levels in

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36

M. A. Diego et al.

terms of severity, with 1 representing “not so much” and 4 repre-
senting “very much.” Characteristic items include “I feel tense” and
“I feel relaxed.” The STAI has adequate concurrent validity (Spiel-
berger, 1972) and internal consistency (r  = .83; Spielberger et al.,
1970). In addition, the STAI scores an increase in response to situ-
ational stress and a decline under relaxing conditions. A summary
score is obtained by adding the weight of each item. A visual ana-
logue scale
 was used to assess the stressed-relaxed state with a
score of O reflecting feeling “very tense” and a score of 10 being
“very relaxed.”

Massage Procedures

Following a 3-min baseline recording, participants received a moder-
ate pressure massage, a light pressure massage, or a vibratory mas-
sage. Participants in all conditions received 10 min of stimulation to
the back, shoulders, and arms by a trained massage therapist, while
sitting fully clothed in a standard massage chair. The moderate pres-
sure massage
 consisted of long, deep pressure stroking, and squeez-
ing; the light pressure massage consisted of long, light pressure
stroking; and the vibratory massage consisted of the Thumper (hand
held massager) vibrating at 40Hz on the deep pressure setting.

The massage therapists were trained on the protocol and did not

play another role in the study. All therapists were kept blind to the
pressure hypothesis. Intermittent re-evaluation by the researchers
ensured protocol compliance, especially with respect to the amount
of pressure provided. Those therapists providing the light pressure
massage did not perform deep pressure massage or vibratory mas-
sage and vice versa.

RESULTS

Demographics

Chi-square tests and independent sample t-tests were conducted on
the demographic variables. These analyses revealed that the massage
and relaxation therapy groups did not significantly differ on any of

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Moderate, Light, and Vibratory Massage

37

the demographic variables (Table 1). The groups did not differ
on their mean Touch Aversion Questionnaire scores (Table 1).

Pre-Post Self-Report Measures

Two separate group (Light/Moderate/Vibratory) by time (pre/post)
repeated measures analyses of variance were conducted on STAI
and visual analogue scale scores (Figure 1). A significant main ef-
fect for time, F(1, 33) = 43.11, p < .001, revealed that state anxiety
scores decreased following all three conditions. A significant group
by time interaction, F(2, 33) = 8.75, p < .001, was found for visual
analogue scale scores. In order to evaluate this interaction, subse-
quent bonferroni corrected t-tests were conducted on visual ana-
logue scale change scores, revealing that participants in the moder-
ate massage group reported a greater decrease in self-reported stress
than participants in the light massage t(22) = 3.60, p < .01 or the
vibratory massage group t(22), 2.58,  p < .05.

TABLE 1. Means (and standard deviations) for demographics of light and moderate
pressure massage and vibratory stimulation groups

Light

Moderate

Vibratory

(N = 12)

(N = 12)

(N = 12)

Age

29.92

29.58

27.42

F(2, 33) = 0.25, N.S.

(10.29)

(8.32)

(9.57)

SES

 2.25

2.75

2.75

F(2, 33) = 2.59, N.S.

(0.62)

(0.75)

(0.45)

Sex

Male

58%

17%

50%

χ

(2) = 4.80, p = N.S.

Female

42%

83%

50%

Ethnicity

χ

(6) = 6.00, p = N.S.

Caucasian

33%

67%

75%

African

8%

8%

8%

American

Hispanic

42%

17%

17%

Other

17%

8%

0%

Touch aversion

35.08

34.25

35.75

F(2, 33) = 0.27, N.S.

(5.59)

(3.82)

(5.56)

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M. A. Diego et al.

EEG Measures

Five separate group (Light/Moderate/Vibratory) by trial (pre/during/
post) repeated measures analyses of variance were conducted on
frontal EEG delta, theta, alpha, beta, and alpha asymmetry values.
The analysis for frontal delta EEG values revealed a significant
group by trial interaction, F(4, 56)  = 2.80, p < .05. In order to
understand this interaction, separate trend analyses were conducted
for each group. These analyses revealed a significant linear trend
for the light massage group, F(1, 11) = 4.93, p < .05, suggesting a
decrease in frontal delta power during and following light massage.
A significant quadratic trend was revealed for the moderate mas-
sage group, F(1, 9) = 8.97, p < .05, involving an increase in frontal
delta power during the deep massage procedure, and then a return
to baseline. The analyses for the remaining EEG measures revealed
significant main effects for frontal alpha F(2, 56) = 3.65, p < .05,
beta F(2, 56) = 3.57, < .05, and alpha EEG asymmetry F(2, 56) =
4.95, < .05. In order to understand better these effects, trend analyses
were conducted revealing the following: (1) a significant quadratic
trend for frontal alpha power F(1, 28) = 3.99, p < .05, suggesting
that alpha power significantly decreased and then returned to baseline
across all massage procedures; (2) a significant linear trend for frontal
beta power F(1, 28) = 8.18, p < .01, suggesting that beta power
significantly decreased and then returned to baseline across all massage

FIGURE 1. Mean pre-post self-reported anxiety (STAI) and stress scores (error bars indi-
cate ± 2 SE) for light and moderate pressure and vibratory stimulation groups.

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Moderate, Light, and Vibratory Massage

39

procedures; and (3) a significant linear trend for frontal alpha asym-
metry F(1, 28) = 8.55, < .01, suggesting that participants became
more left frontal. Moderate pressure massage procedure resulted in
the greatest proportion of adults exhibiting a shift toward left frontal
EEG asymmetry (90% versus 75% for the light pressure massage
and 56% for the vibratory stimulation), and the analyses for frontal
EEG asymmetry yielded a marginal group by trial interaction, F(4,
56) = 2.10, p = .093; separate trend analyses on frontal EEG asym-
metry values were conducted for each group. These analyses re-
vealed that only the moderate pressure massage exhibited a signifi-
cant linear trend towards left frontal EEG asymmetry, F(1, 9) =
5.59, p < .05 (Figure 3).

Heart Rate

A group (Light/Moderate/Vibratory) by trial (pre/during/post) re-
peated measures analysis of variance was conducted on heart rate
values. This analysis revealed a significant group by trial interac-

TABLE 2. Means (and standard deviations) for frontal EEG delta, theta, alpha, beta,
and frontal EEG asymmetry (right minues left) log power values for light and moder-
ate pressure massage and vibratory stimulation groups

Light

Moderate

Vibratory

  Pre

 Dur

Post

 Pre

Dur

Post

Pre

Dur

Post

Delta (1–4 Hz)

3.45

3.10

3.10

3.36 3.68

3.49

3.07

3.05

3.14

Group × Trial

1.33

1.12

1.07

1.39 1.21

1.34

1.07

0.74

1.17

Theta (5–7 Hz)

2.02

1.69

1.93

1.99 1.96

2.16

1.90

1.81

2.00

0.81

0.61

0.61

0.98 0.85

0.81

0.55

0.67

0.81

Alpha (8–12 Hz)

3.01

2.64

2.79

3.15 2.82

2.93

3.04

2.82

3.08

Trial

0.96

0.94

0.92

1.22 1.18

1.29

1.05

0.90

0.80

Beta (13–20 Hz)

2.32

2.13

2.41

2.41 2.20

2.28

2.36

2.27

2.39

Trial

0.67

0.73

0.70

1.03 1.09

1.10

1.16

1.10

1.21

Alpha asymmetry

–0.09 –0.04 –0.01

–0.32 0.00

0.01

–0.25 –0.25 –0.20

Trial

0.38

0.27

0.37

0.45 0.19

0.16

0.43

0.36

0.34

  indicates significant linear trend; 

 indicates significant quadratic trend. Trial indicates significant

main effect for trial (pre/during/post); Group × Trial indicates significant group by trial interaction.

→ →

→ →

→ →

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M. A. Diego et al.

tion,  F(4, 66) = 2.52, p < .05. In order to understand this inter-
action, post-hoc bonferroni corrected t-tests were conducted, reveal-
ing that moderate massage group showed a significant decrease in
heart rate during the massage, t(11) = 5.89, p < .05, which contin-
ued into the post session, t(11) = 3.25, p  < .05, while the light
massage group showed a significant increase in heart rate following
the massage t(11) = 3.40, p <. 05. The vibratory stimulation group
exhibited a marginal increase in heart rate following the massage
t(11) = 2.55, p  < .08.

DISCUSSION

The effects of three types of massage were evaluated on a group of
healthy participants revealing significant effects on self-report mea-
sures of anxiety and stress and on EEG and heart rate. Regardless of
the massage procedure received, participants reported feeling less
anxious and stressed. However, the moderate massage procedure
resulted in the greatest decrease in self-reported stress. The decrease
in self-report anxiety and stress is consistent with findings from

FIGURE 2. Mean heart rate in beats per minute (error bars indicate ± 2 SE) for light
and moderate pressure massage and vibratory stimulation groups.

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