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Research on StepIt™

The following clinical studies are completed or in progress:

1. Prevent leg swelling when sitting for extended time periods such as during long haul flights, in office, in front of TV or similar situations. (Headline of article: Anti-swelling effect of StepIt™ – an active foot pump system)

2. Diabetes – increase of the oxygen tension in the dorsal foot skin (Headline of article: The influence of using a foot pedal (StepIt™) on lower limb swelling and skin oxygen tension.) This study is in progress.

Additional planned clinical study:
3. Persons with the Restless Leg Syndrome
4. Stroke victims
5. Pregnant women with ankle swelling during the third trimester

Clinical Study #1

The following clinical study was accepted for publishing by Journal of American Podiatric Medical Association (JAPMA)

Anti-swelling effect of StepIt™ – an active foot pump system.

D Bergqvist, G Landin, *K Flynner, *B Heide,* A Kusoffsky.
Department of Surgery, Academic Hospital and
*Department of Physical Therapy, Karolinska Institute, Stockholm, Sweden.

Correspondence
David Bergqvist, MD, PhD, FRCS, Professor of Vascular Surgery, Department of Surgical Sciences, Uppsala University Hospital, SE-751 85 Uppsala, Sweden.

Tel: +46 18 611 4633 Fax: +46 18 611 4632 E-mail: david.bergqvist@surgsci.uu.se
Abstract
BACKGROUND:
StepIt™ is a device for active movements of the foot, simulating normal walking with calf muscle contractions.

METHODS:

In 40 healthy volunteers with predominantly office work and sitting conditions, the StepIt™ was used regularly during one day and the volume of the calf, approximated to a truncated code, was measured before and after the use of pumping. One leg was used as control and after five days the exercise was repeated, legs being changed.

RESULTS:
The volume of the leg increased during the day, the increase being significantly smaller in the leg using StepIt™.

CONCLUSION:
By using a device for active foot movements in healthy people it is possible, in some individuals, to reduce swelling occurring during sitting conditions.
Introduction
When sitting immobile for a long period of time, e.g. in the office or in meeting or during long distance flights, many experience ankle swelling and discomfort. During long distance travels passengers often have limited space for legs and feet and limited possibilities to get up and walk. The calf muscles become inactivated which counteracts the emptying of the veins of the feet and lower legs.

A number of studies have been carried out with the aim to investigate whether change of position or body movement could affect the ankle and lower leg swelling 1-3. Besides active movements the rate of emptying of veins can be increased by various passive measures, e.g. elastic compression with special stockings or bandage and various calf muscle pumps. This can also be achieved by active movements. StepIt™ is a pedal device designed to stimulate movements simulating normal walking, which via contraction of the calf muscle pump would assist in emptying the veins of feet and lower leg (Fig.1). Theoretically this would counteract swelling of the ankle and lower leg.

Some of the measures stimulating calf muscle mediated vein emptying have been shown to have a prophylactic effect against the development of postoperative deep vein thrombosis 4-6. One effect of using StepIt™ as walking substitute could therefore be prophylactic against thrombosis.

The aim of the present study was to evaluate whether StepIt™ could influence the tendency towards ankle swelling in persons sitting rather still at work.
Material and Method
The study was conducted in two parts.

In part #1: twenty healthy volunteers were included (19 women, one male, mean age 50 years (29-64), all with office work, predominantly sitting. A history of deep vein thrombosis, bone fracture or surgery in the pelvic region were exclusion criteria.

In part #2: twenty healthy volunteers (16 women and four men; mean age 50 years (23-59) with mostly sitting work were included. A history of deep vein thrombosis, bone fracture or pregnancy were exclusion criteria.

During the days of testing the participants in both parts of the study were asked to sit as much as possible. As indicated below at least 30-40 pumping movements per hour were performed.

The lower leg volume was calculated by measuring the largest calf circumference and the smallest ankle circumference and use these in the formula for the volume of a truncated cone (this is directly comparable to measurement of the displaced water volume) 7.

The formula for the volume (V) of a truncated cone is:
V = h / 12π (C2 + c2 + Cc)
where
C = maximal calf circumference (cm)
c = minimal ankle circumference (cm)
h = the distance between
C and c (cm)

The test persons had one demonstration and verbal explanation on how to use StepIt™, the number of pumping movements and how often. They were instructed to otherwise behave as normally as possible and to avoid longer walks. In part #2 the test persons were instructed to document every pumping period in an activity diary. The volume was measured bilaterally in the morning and the point of measurement was marked with a line. Then StepIt™ was used with one leg (right or left at random) with at least 30-40 pumping movements per hour. The pressure needed to fully depress the StepIt™ is around 6 kg. After six hours of intermittent pumping the circumferences were again measured bilaterally at the same levels as previously marked. After 5 days the procedure was repeated, now using the other leg for pumping with StepIt™.
Statistics
Tables and calculations were performed in Microsoft Excel -97. Nonparametric statistics were chosen since the values could not be assumed to be distributed in a normal Gaussean manner. Wilcoxon’s sign-range test for paired data was used and median and min-max values were noted. The level of significance was determined at p<0.05.
Results
Part # 1 (Table I) On both occasions the leg using StepIt™ showed smaller increase of volume than the contra lateral unpumped (2% vs. 2.9% in mentioned order and 2.5% vs. 3.6% in mentioned order) (p<0.05).

Of the 40 legs 30 showed a smaller volume increase in the pumped leg (30 of the legs showed a smaller volume in the afternoon after pumping than the initial volume in the morning, 9 showed an increase of volume and in one case there was no difference). This difference in number of legs with a prevention of volume increase by using StepIt™ was statistically significant (p<0.05).

Part #2 (Table II) At both measurements there was a significant increase of leg volume during the observation period (p<0.001). There was no significant difference in volume increase between the pumped and unpumped leg, the increase being on average 3.1% in the pumped leg and 3.2% in the unpumped leg. In legs where the increase of volume was more than 4.9%, there was however a significant difference between the pumped and unpumped leg with a smaller volume increase after use of STEPIT (p<0.05).

The median value for volume increase was 2.9% both in the pumped and unpumped leg. Min-max value for pumped/unpumped leg was -2.2%, 6.4%/-1.5%, 17.1%. The pump diary was well kept (441/444 notes or 99.3%).
Discussion
In summary, the studies show that intermittent usage of a foot pedal simulating walking when sitting can diminish the leg volume increase of healthy volunteers with a sitting work situation. How the force necessary to depress the device will influence the antiswelling effect is not known, but the higher the pressure the greater the muscle contraction. Whether a passive movement will reduce swelling is not known. Patients with pathological swelling have not yet been studied, but it can be assumed that the relative effect should be larger. In favour of this assumption speaks the fact that in Part #2 a effect was seen in those with the largest increase of volume. Several studies have indicated a correlation between long term sitting and lower leg swelling. Winkel 8 investigated lower leg swelling and discomfort during an 8 hours working day. The tested persons were examined during three normal working days and three experimental days with a 2 minutes walk every 15th minute during the whole day. The swelling was in average 4% a normal working day and 2.3% during the experimental day. The feeling of discomfort was correlated to the increase of lower leg swelling. In further studies, the same research group has shown the importance of activity to diminish leg swelling 1,9,10.

There are different methods for the measurement of lower leg volume, where water volumetry gives an exact measure, but the calculation of volume from the formula of a truncated cone gives a good correlation (0.97, p<0.001, Persson et al 1989). The method is simple and reliable, requires little equipment and saves time. Therefore it can be used in field studies of volume changes in the lower legs.

In part #1 the test persons did not use a pump protocol but were told to pump 30-40 times per hour. In the normal work of these test persons, movements are part of normal behaviour and it is hard to determine what small or large movement is. At this point we can not determine whether the number of pumping movements would influence the results. Neither did we control how often the test persons pumped or the technique of their pumping. According to the pumping diary control in part #2 the persons showed high compliance which indicates good motivation.

The optimal pumping method (frequency, duration and technique) still needs to be determined as needs the question whether using StepIt™ has different effects on different types of oedema. Another problem to study is whether any prophylactic effect on deep vein thrombosis can be demonstrated. If the pumping has other effects than the hemodynamic, e.g. release of endothelial factors, is not known. An interesting application would be to use StepIt™ on persons with limited ability to move for a long period, e.g. during long distance flights.
Conclusion
In healthy volunteers with mainly sitting working conditions, it is possible, in some people, with the use of StepIt™ to significantly reduce swelling of the lower legs during a working day.
Table I
Volume change (cm3) between second and first measurement (after and before use of StepIt™).
  Leg using Stepit
First measurement
Leg without Stepit
First measurement
Leg using Stepit
Second measurement
Leg without Stepit
Second measurement
  Difference Difference Difference Difference
  Absolute % Absolute % Absolute % Absolute %
Mean 26.5 2.0 40.6 2.9 26.5 2.0 26.5 2.0
Range (-30-116) (-2-7.8) (0-87) (0-7.7) (0-74) (0-7.0) (9-85) (0.7-5.7)
Table II

  Leg with STEPIT
v after - v before
Leg without STEPIT
v after - v before
Difference
Range -14    -    108 -26    -    427 -58    -    356
Mean 45 51 3.1
References
1. Winkel J and Jorgensen K: Evaluation of foot swelling and lower-limb temperatures in relation to leg activity during long-term seated office work. Ergonomics. 29: 313-28, 1986.

2. Paul R: Footswelling in sedentary VDT operators. Advances in Industrial Ergonomics and Safety VII: 623-630, 1995.

3. Stranden E: Dynamic leg volume shanges when sitting in a locked and free floating tilt office chair. Ergonomics. 43: 421-433, 2000.

4. Wells PS, Lensing AW and Hirsh J: Graduated compression stockings in the prevention of postoperative venous thromboembolism. A meta-analysis. Arch Intern Med. 154: 67-72., 1994.

5. Vanek VW: Meta-analysis of effectiveness of intermittent pneumatic compression devices with a comparison of thigh-high to knee-high sleeves. Am Surgeon. 64: 1050-1058, 1998.

6. Agu O, Hamilton G and Baker D: Graduated compression stockings in the prevention of venous thromboembolism. Br J Surg. 86: 992-1004., 1999.

7. Persson NH, Takolander R and Bergqvist D: Lower limb oedema after arterial reconstructive surgery. Influence of preoperative ischaemia, type of reconstruction and postoperative outcome. Acta Chir Scand. 155: 259-66., 1989.

8. Winkel J: Swelling of the lower leg in sedentary work--a pilot study. J Hum Ergol (Tokyo). 10: 139-149, 1981.

9. Noddeland H: Foot swelling and the significance of leg activity during simulated long-distance flying. Acta Physiol Scand. Suppl 542: 130-131, 1985.

10. Winkel J and Jorgensen K: Swelling of the foot, its vascular volume and systemic hemoconcentration during long-term constrained sitting. Eur J Appl Physiol Occup Physiol. 55: 162-6, 1986.

Clinical Study #2

THE INFLUENCE OF USING A FOOT PEDAL (StepIt™ ) ON LOWER LIMB SWELLING AND SKIN OXYGEN TENSION

Busch C1, Bergqvist D2, Bodegard M3 , Brismar K4,
1Department of Pathology, University Hospital, Uppsala, Sweden
2Department of Surgery, University Hospital, Uppsala; 3Medius AB, Uppsala,
4Department of Endocrinology, metabolism and diabetology, Karolinska University Hospital, Stockholm,
Abstract
One important prerequisite in the development of deep vein thrombosis is impaired venous emptying from the calf veins, seen during surgery and other situations of immobilization. Such a situation, which has been discussed, is long journeys, especially air borne, and sitting still in offices, e.g. at a computer screen. Another effect of immobilization is swelling of the lower limb which may be diminished by calf muscle stimulation. Impaired blood perfusion in skin of the lower limb is a well known complication of diabetes depending either on microangiopathy, autonomic neuropathy and / or arterial insufficiency and lead to impaired wound healing, which is one of the most costly diabetes complications.
Aims:
#1
to investigate whether or not the active use of foot pedal simulating walking (StepIt™) has an effect on calf volume.

#2
To study the effect of active use of Stepit on skin oxygenation in the feet of diabetic patients.
Method:
#1
in three groups of volunteers the foot pedal was used on one side, the other serving as control
I 20 persons (50(29-64) years) with mainly sitting office work,

II
20 persons (50(23-59) years) also with mainly sitting office work,

III
44 persons (54(28-80) years) travelling in economy class for five hours, 7 persons using the pedal in both fly directions. The pedal was used at least 30 times per hour. The leg volume was measured with the formula of a truncated cone, the largest calf circumference and the smallest ankle circumference being used. Measurements were made before starting the use of pedal and again after five hours.

#2

50 patients with diabetes type 1 and type 2 with foot ulcers and/or lower leg pain due either to macroangiopathy or peripheral polyneuropathy were tested regarding tissue oxygenation in the feet. TcPO2 (transcutaneus oxygen  tension) was determined using a Radiometer (Copenhagen, Denmark) before and after stimulating circulation by stepping for 1 minute on the a StepIt™.
Results:
#1
In group I the StepIt™ leg showed less swelling than the contra lateral unpedalled leg (p<0.05). In group II no significant difference between the pedalled and unpedalled leg was seen. Swelling was, however, counteracted in legs swelling more than 4.9 %. In group III in 39 legs the foot pedal reduced the swelling, in 12 there was no antiswelling effect (p<0.05).

#2
Stepping the StepIt™ for one minute was shown to discriminate between impaired macrocirculation and microangiopathy +/- neuropathy. Patients who improved TcPO2 with =>10% after using the Stepit was encourage to use a StepIt™ 4-5 times a day for 1-2 minutes.

This is of special importance in patients with foot ulcer who are recommended not to walk but who need to improve the tissue oxygenation. In contrast when TcPO2 was decreased =>10% or was low at basal and unchanged after using the StepIt™ for 1 minute the patients was referred to the vascular surgeon who could confirm significant macroangiopathy with e.g. reduced toe pressure. The prognosis for wound healing was poor in these patients unless revascularisation was performed.
Conclusion:
#1
The regular use of the foot pedal StepIt™ during long term sitting position significantly diminishes leg swelling. This is a beneficial effect per se. Whether or not it prevents deep vein thrombosis during immobilization remains to be studied.

#2
The study is in progress and preliminary results indicate that swelling decreases and skin oxygen tension and temperature increase in patients with microangiopathy, whereas patients with arterial insufficiency seem to have decreased skin oxygen tension and lower temperature.

This method was shown to discriminate between impaired macrocirculation and microangiopathy +/- neuropathy.

Christer Busch, M.D., Ph.D. Professor
Department of Pathology
University Hospital
SE-751 85 Uppsala
Sweden
Phone: +46 18 6113820 Mobile: +46 706333090

Kerstin Brismar, M.D., Ph.D., Professor
Karolinska Institutet
Department of Molecular Medicine and Surgery
Rolf Luft Research Center for Diabetes and Endocrinology
Karolinska University Hospital, Solna, D2:04
171 76 Stockholm
Phone: +46-8-517 728 45 Mobile: +46-706-23 13 84 or 704-84 87 87
stepit

What is Deep Vein Thrombosis (DVT)?
Deep Vein Thrombosis, commonly referred as DVT, occurs with poor blood circulation and a blood clot.....
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Economy Class Syndrome StepIt was originally developed to increase the blood circulation in the lower leg and prevent Economy Class....
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Who can benefit from using StepIt™?
In general, anybody that is more or less immobilized and can not benefit from regular walking exercise....
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Letter of gratitude from the Vice President of the United States
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StepIt™ Registration Food and Drug Administration
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