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The effect of whole-body vibration dosage on leg blood flow was investigated. Nine healthy young adult males completed a set of 14 random vibration and non-vibration exercise bouts whilst squatting on a Galileo 900 plate. Six vibration frequencies ranging from 5 to 30 Hz (5 Hz increments) were used in combination with a 2.5 mm and 4.5 mm amplitude to produce twelve 1-min vibration bouts. Subjects also completed two 1-min bouts where no vibration was applied. Systolic and diastolic diameters of the common femoral artery and blood cell velocity were measured by an echo Doppler ultrasound in a standing or rest condition prior to the bouts and during and after each bout. Repeated measures MANOVAs were used in the statistical analysis. Compared with the standing condition, the exercise bouts produced a four-fold increase in mean blood cell velocity (P<0.001) and a two-fold increase in peak blood cell velocity (P<0.001). Compared to the non-vibration bouts, frequencies of 10-30 Hz increased mean blood cell velocity by approximately 33% (P<0.01) whereas 20-30 Hz increased peak blood cell velocity by approximately 27% (P<0.01). Amplitude was additive to frequency but only achieved significance at 30 Hz (P<0.05). Compared with the standing condition, squatting alone produced significant increases in mean and peak blood cell velocity (P<0.001). The results show leg blood flow increased during the squat or non-vibration bouts and systematically increased with frequency in the vibration bouts.
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Whole-body vibration dosage alters leg blood flow
Noel Lythgo
1
, Prisca Eser
1
, Patricia de Groot
2
and Mary Galea
1
1
Rehabilitation Sciences Research Centre, University of Melbourne, Parkville, Vic., Australia, and
2
Department of Physiology, University Medical Centre, Nijmegen,
The Netherlands
Correspondence
Noel Lythgo, PhD, Rehabilitation Sciences Research
Centre, co Royal Talbot Rehabilitation Centre, 1
Yarra Boulevard, Kew, 3101, Vic., Australia
E-mail: nlythgo@unimelb.edu.au
Accepted for publication
Received 3 June 2008;
accepted 8 September 2008
Key words
blood flow response; common femoral artery; doppler
ultrasound; isometric squat; vibration
Summary
The effect of whole-body vibration dosage on leg blood flow was investigated. Nine
healthy young adult males completed a set of 14 random vibration and non-
vibration exercise bouts whilst squatting on a Galileo 900 plate. Six vibration
frequencies ranging from 5 to 30 Hz (5 Hz increments) were used in combination
with a 2Æ5 mm and 4Æ5 mm amplitude to produce twelve 1-min vibration bouts.
Subjects also completed two 1-min bouts where no vibration was applied. Systolic
and diastolic diameters of the common femoral artery and blood cell velocity were
measured by an echo Doppler ultrasound in a standing or rest condition prior to the
bouts and during and after each bout. Repeated measures MANOVAs were used in
the statistical analysis. Compared with the standing condition, the exercise bouts
produced a four-fold increase in mean blood cell velocity (P<0Æ001) and a two-fold
increase in peak blood cell velocity (P<0Æ001). Compared to the non-vibration
bouts, frequencies of 10–30 Hz increased mean blood cell velocity by approximately
33% (P<0Æ01) whereas 20–30 Hz increased peak blood cell velocity by approxi-
mately 27% (P<0Æ01). Amplitude was additive to frequency but only achieved
significance at 30 Hz (P<0Æ05). Compared with the standing condition, squatting
alone produced significant increases in mean and peak blood cell velocity
(P<0Æ001). The results show leg blood flow increased during the squat or non-
vibration bouts and systematically increased with frequency in the vibration bouts.
Introduction
Indirect vibration of the body, commonly referred to as whole-
body vibration, has become a popular exercise method in recent
years. It can be delivered to the body through a hand-held
vibrating bar (Issurin & Tenenbaum, 1999) or through the feet
by an oscillating platform (Rittweger et al., 2001). Currently,
there are two types of vibration platforms available on the
market. A platform that moves or oscillates in a vertical direction
(fixed frequency and amplitude) and a platform that rotates
about a fixed horizontal axis (variable frequency and ampli-
tude). This investigation utilized the latter type of platform as
frequency and amplitude (peak-to-base displacement) can be
changed. Additionally, this system does not directly accelerate
the bodys centre of mass and therefore larger peak accelerations
are tolerated than with linear acceleration. The aim of this study
was to investigate the effect of whole-body vibration on leg
blood flow velocity when delivered at different dosage levels
(frequency and amplitude) by a rotary style plate. This
information is important in order to ascertain whether whole-
body vibration delivered by these systems might provide
therapeutic benefit to people with reduced or impeded leg
blood flow such as the elderly or those with diabetes mellitus.
Many effects of low-frequency (50 Hz or less) whole-body
vibration have been reported in the literature. These include
increased leg power, strength and flexibility in athletes (Bosco
et al., 1999; Mester et al., 2006; Rees et al., 2008), increased
bone formation in post-menopausal women (Russo et al., 2003;
Verschueren et al., 2004), improved postural control and
mobility in adults with multiple sclerosis (Schuhfried et al.,
2005) and reduced arterial atrophy in people undergoing bed
rest (Bleeker et al., 2005). Immediate effects include increased
oxygen consumption, heightened muscle activity and leg blood
flow velocity in healthy adults and increased knee extension
strength in recovering stroke patients (Rittweger et al., 2000;
Kerschan-Schindl et al., 2001; Cardinale & Bosco, 2003; Tihanyi
et al., 2007a). On the other hand, there is evidence to show that
high-frequency vibration (above 80 Hz) can restrict blood flow
(Greenstein & Kester, 1992; Bovenzi et al., 1999) and even cause
hypertrophy of the smooth vascular muscle cells (Takeuchi et al.,
1986). These problems are often encountered by operators of
power tools.
Only a few studies involving healthy young adults have
investigated the effect of whole-body vibration on leg blood
flow. Kerschan-Schindl et al. (2001) found vibrations delivered
by a rotary type platform with a frequency of 26 Hz and
Clin Physiol Funct Imaging (2009) 29, pp53–59 doi: 10.1111/j.1475-097X.2008.00834.x
2008 The Authors
Journal compilation 2008 Scandinavian Society of Clinical Physiology and Nuclear Medicine 29, 1, 53–59 53
amplitude of 3 mm (Galileo 2000, Novotec, Pforzheim,
Germany) doubled leg blood flow (measured with a Doppler
ultrasound system) after 9 min of vibration. Zhang et al. (2003)
similarly found increased leg blood flow, measured by photo-
plethysmography, after direct transmission of vibration to the
foot of subjects (Zhang et al., 2003).
Our hypothesis was that leg blood flow systematically
increases with vibration frequency (up to 30 Hz) and amplitude
(up to 4Æ5 mm). Blood flow velocity, measured by a Doppler
ultrasound system, in the common femoral artery of a group of
healthy young adults was recorded before, during and after
1-min bouts of whole-body vibration (Radegran, 1997;
Radegran & Saltin, 1998).
Methods
Subjects
Nine healthy, community-dwelling male adults participated in
this study (age = 21Æ8 years, SD = 4Æ4 years; stature =
175Æ6 cm, SD = 6Æ3 cm; mass = 75Æ0 kg, SD = 9Æ1 kg). Sub-
jects were recruited from staff and students of the University of
Melbourne. Exclusion criteria were smoking, known vascular
disease and diabetes. Subjects were not allowed to consume
caffeine 12 h before testing or food 3 h before testing.
Additionally, no strenuous exercise was permitted 48 h before
testing. Written informed consent was obtained from each
subject. The study was approved by the Human Research Ethics
Committee of the University of Melbourne and performed in
accordance with the ethical standards laid down in the 1964
Declaration of Helsinki.
Study protocol
Each subjects stature, mass and age were recorded. Subjects
wore a pair of loose-fitting shorts, a T-shirt and were
barefooted. Prior to the session, subjects lay in a supine position
on a plinth for a period of 5 min. Following this period, the
diameters (systolic and diastolic) and red blood cell velocity
(BCV) of the common femoral artery of each subjectsright leg
were recorded by a pulsed colour-coded Doppler ultrasound
device with a 5–10 MHz broadband linear array transducer
(LOGIQBook, GE Medical, Milwaukee, WI, USA). The
transducer was placed in the centre of the common femoral
artery about 2 cm above the bifurcation into the superficial and
deep femoral arteries. Two images of the common femoral
artery diameters were recorded during the peak systolic and
end-diastolic phases (as determined from flow profile). For the
blood cell velocity measurements, the transducer was positioned
parallel to the vessel with the inclination angle held below 60.
This protocol was used by the same investigator throughout the
study.
The ultrasound probe was held in the same position
throughout the test session. This was possible as only the legs
were accelerated by the vibration plate whereas the body from
the hips upwards remained relatively still due to the dampening
of the vibration by the ankles, knees and hips. This was
investigated at the beginning of the study with a 3D
accelerometer (HOBOware; Onset Computer Corp., Bourne,
MA, USA) placed on the site of the ultrasound probe. A subject
stood in the squat position on the vibration plate for five 1-min
bouts of vibration with 1-min rest between each bout.
Amplitude and frequency were set at 4Æ5 mm and 30 Hz
respectively so as to produce the highest acceleration. The
accelerometer was set at 100 Hz and recorded the resultant
acceleration for each 1-min bout. On a second occasion, the
accelerometer was gripped between the teeth in order to
measure the acceleration experienced at the head. The resultant
acceleration, including gravity, experienced at the ultrasound
probe site and head (gripped between teeth) were 1Æ07 g
(SD = 0Æ06 g) and 1Æ01 g (SD = 0Æ03 g) respectively. These
values fall well below the ISO2631 zone where health risks are
likely (Mansfield, 2005).
The placement site for the probe was easily identified by
anatomical landmarks. Once identified it was marked with a
crayon. In order to establish the reliability of the measurement
protocol, intraclass correlation coefficients (ICCs) (Portney &
Watkins, 2000) were calculated for the common femoral artery,
mean BCV and peak BCV data recorded during the standing
position before each exercise bout. In total, 14 measures of these
data were recorded for each subject. These values were found to
demonstrate good reliability. The ICCs for the common femoral
artery, mean BCV and peak BCV data recorded prior to the
vibration bouts were 0Æ997, 0Æ868 and 0Æ935 respectively
(P<0Æ001).
The vibration frequency of the plate was set by an operator,
whereas amplitude was set by the position of the feet on the
plate. Feet were placed parallel to each other at 28 or 50 cm apart
(measured from the midlines of the feet). The smaller distance
corresponded to a 2Æ5 mm amplitude (peak-to-base displace-
ment), whereas the larger distance corresponded to a 4Æ5mm
amplitude. Six vibration frequencies ranging from 5 to 30 Hz
(full range of system) at 5 Hz increments were used in
combination with the two amplitudes to produce 12 exercise
bouts of vibration. Subjects also completed another two exercise
bouts where no vibration was applied (a bout for each foot
placement or amplitude condition). In total 14 exercise bouts
were completed: 12 vibration bouts and two non-vibration
bouts. The 14 exercise bouts were randomized for each subject.
During each bout a squat posture was adopted with 50of knee
flexion (as measured by a goniometer) with weight supported
on the forefeet. This posture was adopted in order to minimize
transmissibility of the ground-based vibrations to the pelvis and
upper body. Previous work has shown a bent knee posture
greatly attenuates the mechanical signals generated by vibration
(Rubin et al., 2003). A straight leg posture was not used as
unacceptably high accelerations can be transmitted to the upper
body (Griffin, 1998). All subjects were encouraged to report any
unusual symptoms (e.g. discomfort, queasiness) and were
allowed to stop the vibration at any time.
Whole-body vibration dosage, N. Lythgo et al.
2008 The Authors
Journal compilation 2008 Scandinavian Society of Clinical Physiology and Nuclear Medicine 29, 1, 53–59
54
Prior to each exercise bout, subjects sat on a chair and rested
for 3 min before standing on the vibration plate (Novotec).
Subjects stood on the plate (not activated) for a period of 1 min
whilst common femoral artery diameters (systolic and diastolic)
and BCVs were recorded. Following this period, the subjects
flexed the knees and hips to achieve 50 degrees of flexion and
lightly grasped a handrail. The plate was then activated for a
period of 1 min. One minute exercise bouts were used as it is
difficult for people to hold a squat position, especially at high
vibration frequencies, for periods greater than 1 min (Mester
et al., 2006). Upon completion of a bout, each subject slowly
returned to a standing position (within 5 s) and then remained
on the plate for a period of 2 min. Continuous recordings of
BCV were made during the exercise bouts and for 2 min after
each bout. Common femoral artery (CFA) diameters were
captured 2 min after each bout. These recording processes were
repeated for each bout and took about 7 min. Overall, the test
session for each subject lasted about 1 h and 45 min.
Heart rate and blood pressure were recorded by a UA-767
Plus blood pressure monitor (A & D Medical, Milpitas, CA, USA)
in the supine and the standing positions before each bout,
during each bout (45 s into exercise bout), and at 1- and 2-min
after each bout.
Data analysis
Common femoral artery diameter measures were taken in the
standing period before each bout and 2-min after each bout.
Three diameter readings were extracted from two images. An
average diameter was calculated from these readings.
On average, five blood cell velocity profiles were captured at
the following time points: (i) 30 s before each exercise bout
during which the subjects were standing; (ii) at 15, 30 and 45 s
during each exercise bout: and, (iii) at 5, 10, 15, 30, 45, 75 and
105 s of quiet standing after each exercise bout. These were
automatically recorded by software that drew an envelope
around the root mean square signal. This information was used
to extract mean and peak BCV data.
Statistical analysis
SPSS
(version 12.0.1) was used for all statistical analyses. A two-
way repeated measures MANOVA was used to examine the
effects of amplitude and frequency. In order to further examine
the effect of frequency, the BCV measures recorded at 15, 30
and 45 s into the vibration bouts of 5–30 Hz were compared
with the same measures recorded during the non-vibration
bouts (standing in squat position). Heart rate and blood
pressure measures recorded at 45 s into the vibration bouts of
5–30 Hz were also compared with the equivalent measures
recorded during the non-vibration bouts. Common femoral
artery diameters recorded 1-min before an exercise bout
(standing position) were compared with common femoral
artery diameters recorded 2-min after the bout (standing
position).
One-way repeated measures MANOVAs were used to deter-
mine when BCV, heart rate and blood pressure measures had
returned to resting levels (recorded during the standing position
before the exercise bouts). Specifically, BCV measures recorded
at 5, 10, 15, 30, 45, 75 and 105 s after the bouts (subjects had
returned to a standing position) were compared with resting
levels recorded in the standing position before the exercise
bouts. The alpha level was set to 0Æ01 for this part of the analysis
due to the high number of comparisons. The supine measure-
ments were not used in the MANOVA analyses and were only
used for reference.
Results
A typical plot of a BCV signal recorded during and after a
vibration exercise bout (30 Hz and 2Æ5 mm) is shown in Fig. 1.
This plot shows two signals during the period of vibration (left
panel) and one signal after vibration (right panel). Importantly,
the pattern and magnitude of the BCV signal recorded during
and after vibration are similar; that is, the signal was unaffected
by vibration. For comparison purposes, the heart rate, blood
pressure, CFA diameter and BCV data recorded during the
supine and standing positions before the exercise bouts are listed
in Table 1.
Statistical analysis revealed the CFA diameter measures were
not affected by vibration amplitude and frequency. For this
reason, these data are not presented in this paper. In contrast,
mean blood cell velocity (refer to Table 2) increased over three-
fold (c. 46 cm s
)1
) during the non-vibration exercise bouts
(squat only) and over four-fold (c. 59 cm s
)1
) during the
vibration exercise bouts (squat with vibration) when compared
to the mean blood cell velocity (c. 14 cm s
)1
) recorded during
the standing position immediately before the exercise bouts
(Table 1).
Vibration amplitude had a significant affect upon blood cell
velocity (refer to Fig. 2). Mean BCV measures recorded 45 s
into the exercise bouts were significantly increased by the
4Æ5 mm amplitude condition (P=0Æ018). This condition
resulted in a 27% higher mean BCV value (P=0Æ013) than
–4 –3 –2 –1 0 –50
50
(cm/s)
100
150
Figure 1 Ultra-sound blood cell flow velocity signal over a 4 s time
period during and at the end of a vibration bout of 30 Hz frequency and
2Æ5 mm amplitude. The horizontal axis indicates time in seconds and the
y-axis indicates blood cell velocity in cm s
)1
. The arrow identifies the
termination of the vibration. Squatting position was unchanged during
the shown sequence.
Whole-body vibration dosage, N. Lythgo et al.
2008 The Authors
Journal compilation 2008 Scandinavian Society of Clinical Physiology and Nuclear Medicine 29, 1, 53–59
55
Table 1 Descriptive statistics for heart rate, blood pressure, CFA diameter and blood cell velocity recorded in the supine and standing positions before the exercise bouts.
Subject
Supine Standing
HR
bpm
BP
sys
[mmHg]
BP
dia
[mmHg]
CFA
diameter
sys
[mm]
CFA
diameter
dia
[mm]
Mean
velocity
[cm s
)1
]
Peak
velocity
[cm s
)1
]
HR
bpm
BP
sys
[mmHg]
BP
dia
[mmHg]
CFA
dia-meter
sys
[mm]
CFA
dia-meter
dia
[mm]
Mean
velocity
[cm s
)1
]
Peak
velocity
[cm s
)1
]
1 45 110 68 1Æ16 1Æ15 15Æ5 106Æ2 53 124 84 1Æ18 1Æ17 8Æ952Æ4
2 60 107 63 0Æ92 0Æ91 13Æ2 119Æ4 72 110 77 0Æ95 0Æ95 17Æ064Æ7
3 61 107 55 0Æ91 0Æ88 10Æ793Æ4 78 117 74 0Æ94 0Æ92 15Æ871Æ7
4 67 114 71 0Æ90Æ90 18Æ1 112Æ2 75 112 85 0Æ94 0Æ93 28Æ871Æ3
5 51 110 64 0Æ97 0Æ96 18Æ1 111Æ0 54 124 76 1Æ01 1Æ00 6Æ749Æ5
6 67 112 69 0Æ87 0Æ87 14Æ4 155Æ3 83 115 85 0Æ94 0Æ93 12Æ168
Æ2
7 65 112 95 0Æ80 0Æ80 8Æ0 121Æ5 75 116 95 0Æ89 0Æ90 15Æ677Æ5
8 66 128 78 0Æ96 0Æ96 33Æ9 125Æ4 75 129 94 1Æ02 1Æ02 8Æ337Æ5
9 66 157 98 1Æ01 1Æ01 9Æ586Æ8 65 158 110 1Æ05 1Æ04 11Æ656Æ9
Mean 61 117 73 0Æ94 0Æ94 15Æ7 114Æ6 70 123 87 0Æ99 0Æ98 13Æ961Æ1
SD 8 16 15 0Æ10 0Æ10 7Æ719Æ910Æ515 11 0Æ09 0Æ08 6Æ712Æ9
Table 2 Descriptive statistics for heart rate, blood pressure and blood cell velocities at 45 s into the 60 s of the exercise bouts.
Frequency [Hz] HR [bpm] BP
sys
[mmHg] BP
dia
[mmHg] BCV
mean
[cm s
)1
] BCVpeak [cm s
)1
]
Amplitude
[mm]
2Æ54Æ5
a
2Æ54Æ5
a
2Æ54Æ52Æ54Æ5
a
2Æ54Æ5
Non-
vibration
79Æ6 (10Æ4) 80Æ2(9Æ2) 121Æ4 (10Æ8) 118Æ7 (15Æ9) 86Æ7 (11Æ9) 84Æ8 (13Æ4) 45Æ4 (12Æ8) 46Æ6 (10Æ5) 99Æ1 (18Æ7) 105Æ5 (20Æ3)
584Æ9* (7Æ7) 95* (3Æ8) 120Æ4 (13Æ0) 132Æ2 (12Æ3) 83 (14Æ3) 87Æ2 (10Æ5) 47Æ7 (12Æ2) 48Æ5 (11Æ7) 122Æ8* (23Æ5) 118Æ2* (28Æ0)
10 92Æ8* (4Æ0) 96Æ8* (8Æ6) 114 (9Æ7) 120Æ3 (17Æ9) 82Æ3(4Æ6) 83Æ5(8Æ2) 52Æ1** (14Æ6) 56Æ2** (8Æ2) 110Æ7** (25Æ3) 119Æ3** (21Æ0)
15 82Æ8* (10Æ0) 92* (6Æ3) 123Æ1 (12Æ3) 119Æ1 (12Æ1) 81Æ7(9Æ3) 80Æ3 (12Æ7) 53Æ3* (10Æ9) 58Æ8* (15Æ1) 118** (27Æ4) 122Æ8** (27Æ1)
20 80Æ6 (10Æ8) 85Æ6 (10Æ9) 121Æ2 (16Æ5) 128Æ4 (16Æ3) 80Æ8 (12Æ8) 88Æ4 (10Æ4) 58Æ9* (11Æ1) 64Æ1* (19Æ5) 121Æ4* (18Æ9) 121Æ8* (31Æ0)
25 84Æ3(8Æ6) 83Æ6 (11Æ4) 123 (8Æ6) 121 (6Æ8) 88Æ8 (15Æ6) 85Æ8 (12Æ9) 57Æ7* (14Æ1) 70Æ4* (21Æ3) 119Æ2* (23Æ0) 132Æ9* (35Æ4)
30 81Æ3 (10Æ6) 85Æ1 (11Æ8) 115Æ8 (11Æ4) 132Æ7 (20Æ4) 82Æ1(6Æ4) 88Æ9 (13Æ7) 61Æ5* (15Æ5) 78Æ4* (21Æ8) 129Æ8* (29Æ2) 151Æ8* (41Æ4)
a
P<0Æ01 for main effect of amplitude.
*P<0Æ01 for main effect of frequency (compared to non-vibration bout).
**P<0Æ05 for main effect of frequency (compared to non-vibration bout).
Whole-body vibration dosage, N. Lythgo et al.
2008 The Authors
Journal compilation 2008 Scandinavian Society of Clinical Physiology and Nuclear Medicine 29, 1, 53–59
56
the 2Æ5 mm amplitude condition (refer to Table 2). The larger
amplitude was also associated with (P=0Æ004) higher heart
rate and systolic blood pressure measures (Table 2). On average,
heart rates during the 4Æ5 mm bouts were approximately 5%
higher than the 2Æ5 mm bouts.
Vibration frequency was found to have a significant effect
upon the measures of blood cell velocity (P<0Æ001). During
vibration bouts of 10 Hz and above (i.e. squat with vibration),
mean BCVs measured at the 15 and 45 s marks were
significantly higher (P<0Æ05) than velocities recorded at the
equivalent time points during the non-vibration bouts where
subjects only stood in the squat position on the vibration plate
(refer to Table 2 and Fig. 2). On average, the 30 Hz vibration
bouts resulted in mean BCV values of about 70 cm s
)1
that were
approximately 50% higher than the non-vibration bouts
(c. 46 cm s
)1
). Similarly, vibration frequencies of 5 Hz and
above resulted in significantly higher peak BCV values than the
non-vibration bouts (P<0Æ05). On average, the vibration bouts
resulted in peak BCV values (c. 127 cm s
)1
) that were about
25% higher than the non-vibration bouts (c. 102 cm s
)1
).
Blood cell velocity (mean and peak values) rose sharply in the
initial 15 s (refer to Fig. 2) and increased at a lesser rate until
the end of the exercise bouts. Compared with the rest condition
(standing with straight legs before a bout), these measures
remained elevated for 30 s after each bout (P<0Æ01) but
decreased rapidly thereafter. Seventy-five seconds after the
bouts, these measures had returned to resting levels.
Discussion
Compared with the mean blood cell velocity recorded in the
standing position immediately prior to the exercise bouts
(13Æ9cms
)1
), whole-body vibration of 4Æ5 mm amplitude at
frequencies of 20–30 Hz produced a five-fold increase in mean
BCV (c. 71 cm s
)1
) whereas vibration of 2Æ5 mm amplitude at
frequencies of 20–30 Hz produced a four-fold increase in mean
BCV (c. 60 cm s
)1
). Interestingly, the non-vibration condition,
where subjects stood in the squat posture with no vibration
produced a three-fold increase (c. 46 cm s
)1
) in mean BCV.
Hence, squatting alone produces significant increases in mean
blood cell velocity.
In a previous study that used the same vibration device,
Kerschan-Schindl et al. (2001) found a two-fold increase in
mean blood flow velocity in the popliteal artery after a 9 min
vibration bout at 26 Hz and 3 mm amplitude. The difference in
blood flow response is most likely due to differing methodo-
logies as this study used the common femoral artery whereas
Kerschan-Schindl used the popliteal artery. The common
femoral artery supplies the whole leg whereas the popliteal
artery only supplies the ankle extensors.
4·5 mm amplitude
0
10
20
30
40
50
60
70
80
90
Time (s)
Mean BCV (cm/s)
30 Hz
25 Hz
20 Hz
15 Hz
10 Hz
5 Hz
Squat
Vibration Recovery
*
*
**
**
2·5 mm amplitude
0
10
20
30
40
50
60
70
80
90
Time (s)
Mean BCV (cm/s)
30 Hz
25 Hz
20 Hz
15 Hz
10 Hz
5 Hz
Squat
Vibration Recovery
*
*
4·5 mm amplitude
40
60
80
100
120
140
160
180
Rest 15 30 45 5 10 15 30 45 75 105 Rest 15 30 45 5 10 15 30 45 75 105
Rest 15 30 45 5 10 15 30 45 75 105
Rest 15 30 45 5 10 15 30 45 75 105
Time (s)
Peak BCV (cm/s)
30 Hz
25 Hz
20 Hz
15 Hz
10 Hz
5 Hz
Squat
Vibration Recovery
*
*
*
**
**
2·5 mm amplitude
40
60
80
100
120
140
160
180
Time (s)
Peak BCV (cm/s)
30 Hz
25 Hz
20 Hz
15 Hz
10 Hz
5 Hz
Squat
Vibration Recovery
*
*
Figure 2 Plots of mean (top panels) and peak (bottom panels) blood cell velocity at different frequencies and amplitude. The large amplitude
plots (4Æ5 mm) are shown in the left panels, whereas the small amplitude plots (2Æ5 mm) are shown in the right panels. Error bars depict standard
errors and are only shown for the non-vibration bouts and the 30 Hz vibration frequency bouts. **P<0Æ05 for MANOVA interactive effect of frequency
and amplitude, *P<0Æ01 for MANOVA main effect of frequency.
Whole-body vibration dosage, N. Lythgo et al.
2008 The Authors
Journal compilation 2008 Scandinavian Society of Clinical Physiology and Nuclear Medicine 29, 1, 53–59
57
The concomitant increase of blood flow velocity and heart
rate suggests that muscle metabolic demand drove the increased
blood flow. This is supported by Rittweger and colleagues
(Rittweger et al., 2002) who investigated oxygen uptake during
whole-body vibration delivered by a Galileo plate with three
frequencies of 18, 26 and 34 Hz and three amplitudes of 2Æ5,
5 and 7Æ5 mm. They found a proportional increase in oxygen
uptake with increasing vibration frequency and a small increase
from 2Æ5 to 5 mm amplitude and a larger increase from 5 to
7Æ5 mm. In another study, squatting on a rotary vibration plate
at a frequency of 26 Hz and amplitude of 6 mm was found to
increase oxygen uptake by 4Æ5 ml min
)1
kg
)1
(Rittweger et al.,
2001). This study, however, did not compare oxygen demand
during vibration to oxygen demand during isometric squatting.
Our study found that 1-min of isometric squatting increases
blood flow to the legs two-threefold compared to quiet
standing. A rise in mean and peak BCV (significant at P<0Æ001
for both amplitudes) was found 5 s after the bouts, which was
when subjects started to slowly return to a standing position.
This implies the presence of ischemia in the knee and ankle
extensors with 1-min of isometric squatting causing the
compensatory increase in blood flow after relaxation of the
isometrically contracting muscles. A rise in BCV was also found
after some of the whole-body vibration bouts, however, this rise
tended to be smaller than after isometric squatting and at some
frequencies it was even absent (Fig. 2). This indicates that
whole-body vibration may prevent at least some of the ischemia
that develops during isometric contraction in a static squatting
position.
A study by Rittweger and colleagues (Rittweger et al., 2000)
compared responses in heart rate and blood pressure immediately
after slow squatting on a vibration plate to exhaustion and cycle
ergometry to exhaustion. A Galileo vibration device was used
with a frequency of 26 Hz and amplitude of 5Æ3 mm. Squatting
(at 3 s down and 3 s up) was performed with an additional load
fixed around the waist of 40% body mass for males and 35% body
mass for females. Heart rate and systolic blood pressure increased
after whole-body vibration squatting to exhaustion, but these
increases were significantly less than after cycling to exhaustion.
Diastolic blood pressure decreased significantly more after whole-
body vibration squatting compared to cycling. They suggested
that arterial vasodilation may have caused the drop in diastolic
blood pressure at concomitant increases of systolic blood pressure
and heart rate, but could not specify whether the dilation
occurred during or only after cessation of whole-body vibration.
The present study found no effect of vibration on diastolic blood
pressure. The different findings between our study and that of
Rittweger and colleagues is most likely due to the active exercise
employed, whereas our study employed quasi-isometric muscle
contractions; the small vibration amplitude causes small changes
in hip, knee and ankle angles, however these changes may be
compensated for by passive rather than active structures of the
muscle-tendon apparatus.
Vibration may lead to an increase in shear forces at
the vascular endothelium due to the inertia of the blood.
Endothelial-derived vasodilators such as nitric oxide and
prostaglandins are thought to be released as a response to
increased shear forces at the vascular endothelium. Shear stress
at the endothelium represents the frictional force of the blood
on the endothelial layer and is dependent on blood flow
velocity, vessel diameter and blood viscosity. As common
femoral artery diameter remained unchanged 2 min after
vibration, there is no indication that endothelial dependent
vasodilation in conduit arteries was a contributing factor in the
present study. As with this study, Kerschan-Schindl and
colleagues also found no change in systolic arterial diameter
before and after vibration (Kerschan-Schindl et al., 2001;
Tihanyi et al., 2007b). It is proposed, therefore, that the increase
in blood flow with whole-body vibration is most likely due to
heightened muscle activity and muscle metabolic demand
resulting from the activation of muscle spindle reflexes
(Cardinale & Wakeling, 2005).
Kerschan-Schindl and colleagues have proposed that
a reduction in blood viscosity may be another possible
mechanism for increased blood flow after whole-body vibration
(Kerschan-Schindl et al., 2001). While this seems plausible, it is
unclear as to why blood viscosity would remain affected after a
bout of whole-body vibration.
A limitation of this study was that the squat posture could not
be maintained throughout the 2 min follow-up period after the
vibration bout, instead, subjects returned to a standing position
within 5 s of the bout. This meant that the follow-up period was
performed in a different position. However, even if subjects
could have managed to squat longer, muscle fatigue would have
started to affect the measurements. Fatigue cannot be excluded
in the present study, however, fatigue would have affected all
trials at different frequencies (including the non-vibration bout)
similarly, hence the comparison of 5–30 Hz to the non-
vibration condition is still valid.
The results of this investigation show that isometric
squatting alone can significantly increase leg blood flow.
Significant increases in leg blood flow were also found with
whole-body vibration. Increasing frequency produced system-
atic increases in leg blood flow whereas the increase in
amplitude was found to be additive to frequency. The
4Æ5 mm amplitude, for example, only produced a significant
increase in leg blood flow when combined with a 30 Hz
frequency. Essentially, isometric squatting during short 1-min
bouts of whole-body vibration is an exercise modality that
increases leg blood flow and muscle activity above that
achieved by isometric squats alone. However, squatting alone
produces significant increases in leg blood flow. All consid-
ered, whole-body vibration may be a safe and effective
exercise modality to increase leg blood flow providing a
person can dampen the vibration experienced at the pelvis,
upper body and head. Based on the findings of this study, it
is reasonable to conclude that a vibration amplitude of
2Æ5 mm coupled with vibration frequencies in the order
5–20 Hz produce significant increases in leg blood flow that
are higher than that achieved by isometric squatting alone.
Whole-body vibration dosage, N. Lythgo et al.
2008 The Authors
Journal compilation 2008 Scandinavian Society of Clinical Physiology and Nuclear Medicine 29, 1, 53–59
58
Higher amplitudes and frequencies are not warranted due to
the fact that high accelerations may be transmitted to the
upper body.
Acknowledgments
The Galileo vibration plate was kindly provided by Novotec,
Pforzheim, Germany.
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