In JoVE (1)

Other Publications (20)

Articles by Jerrold S. Petrofsky in JoVE

Other articles by Jerrold S. Petrofsky on PubMed

Toward the Optimal Waveform for Electrical Stimulation of Human Muscle

European Journal of Applied Physiology. Nov, 2002  |  Pubmed ID: 12436266

Electrical stimulation of the quadriceps muscle was used to elicit 4-min isometric contractions at 10% of the maximal voluntary contraction (MVC) in four male and three female subjects. The effect of four waveforms, including Russian, interferential, sine, and square, on the mean stimulation current required to achieve the desired contraction force, subjective comfort, and physiological responses was studied. Interferential stimulation, even at full power, could not elicit a sustained contraction at 10% MVC. The contractions elicited by electrical stimulation utilizing the sine waveform required significantly less mean stimulation current to maintain the desired force of contraction with consistently lower verbal rating scale scores and greater increases in oxygen consumption than either the Russian or square waveform stimulations. Russian waveform stimulation produced a significantly greater rise in galvanic skin resistance than the sine or square waveform while the changes in respiratory quotient were similar between waveforms. The data support sine wave stimulation as working the best by producing the desired muscle tension with the least mean stimulation current and therefore, the least tissue trauma while providing the most subjective comfort.

The Effect of Aging on Conductive Heat Exchange in the Skin at Two Environmental Temperatures

Medical Science Monitor : International Medical Journal of Experimental and Clinical Research. Oct, 2006  |  Pubmed ID: 17006398

Ageing diminishes the blood flow (BF) response of the skin to autonomic stressors. While the diminished response of skin BF to global heating has been well documented, the effect of this reduction in skin BF on the ability of the skin to dissipate heat has not. When heat is added to the skin by the application of hot packs, if heat is not adequately removed, the skin can become dangerously hot and become damaged. The present investigation examined the heat dissipating properties of the skin in older individuals. This study has importance for the therapeutic application of hot packs which might cause burns easier in older people.

The Influence of Local Versus Global Heat on the Healing of Chronic Wounds in Patients with Diabetes

Diabetes Technology & Therapeutics. Dec, 2007  |  Pubmed ID: 18034608

In a previous study, it was shown that placing a subject with chronic diabetic ulcers in a warm room prior to the use of electrical stimulation dramatically increased the healing rate. However, global heating is impractical in many therapeutic environments, and therefore in the present investigation the effect of global heat versus using a local heat source to warm the wound was investigated.

The Thermal Effect on the Blood Flow Response to Electrical Stimulation

Medical Science Monitor : International Medical Journal of Experimental and Clinical Research. Nov, 2007  |  Pubmed ID: 17968297

Wounds, especially in the elderly, can be life threatening. One modality which allegedly increases blood flow (BF) as an aid to heal chronic wounds is electrical stimulation. This technique applies electrical current (ES) across wounds. However, while many studies show positive findings, others do not. The purpose of this investigation was to investigate some of this inconsistency in results by determining the effect of environmental temperature on the circulation of the skin which may negate the effects of electrical stimulation in a clinical setting.

A Randomized Control Study on the Effect of Biphasic Electrical Stimulation in a Warm Room on Skin Blood Flow and Healing Rates in Chronic Wounds of Patients with and Without Diabetes

Medical Science Monitor : International Medical Journal of Experimental and Clinical Research. Jun, 2007  |  Pubmed ID: 17534231

Decrease in skin blood flow (BF) due to diabetes may be one reason why only 31% of neuropathic diabetic ulcers heal in 20-weeks. Recent evidence shows that skin blood flow may be increased if therapy is done in a warm room. The purpose of this investigation was to compare healing rates and skin blood flow of chronic stage III and IV wounds in people with diabetes (D) and those without diabetes (WD) using a warm room and electrical stimulation.

Skin Heat Dissipation: the Influence of Diabetes, Skin Thickness, and Subcutaneous Fat Thickness

Diabetes Technology & Therapeutics. Dec, 2008  |  Pubmed ID: 19049378

It is well established that diabetes impairs vascular endothelial function. However, the impact of impaired endothelial function on thermal conductivity of the skin, especially in relation to a constant versus a sudden heat stress, has not been established. Further, there is some evidence that aging reduces skin dermal thickness and subcutaneous fat thickness. Since these are important determinates of heat dissipation by the skin, these parameters also need to be examined in people with diabetes.

Relationship Between Multiple Stimuli and Skin Blood Flow

Medical Science Monitor : International Medical Journal of Experimental and Clinical Research. Aug, 2008  |  Pubmed ID: 18667996

The environment surrounding vascular endothelial cells determines the contractile state of vascular smooth muscle. The present investigation examined the interrelationships between 3 factors known to effect skin blood flow (global heat, local heat and electrical stimulation) to see how they interacted.

Interrelationships Between Body Fat and Skin Blood Flow and the Current Required for Electrical Stimulation of Human Muscle

Medical Engineering & Physics. Sep, 2008  |  Pubmed ID: 18243763

There is variability between individuals in the current needed to elicit a contraction in human muscle with surface electrodes. To understand what might be causing some of this variability, 25 subjects whose average age was 24.4+/-2.3 years, whose height was 165.5+/-9.5 cm, and whose average weight was 70.3+/-21 kg were examined. Electrical stimulation was applied above the motor point of the quadriceps, biceps, and lateral gastrocnemius muscles. To assess body fat, 2D ultrasound was used with a 1cm stand off. Electrical stimulation was applied with sine wave stimulation at 100 micros pulse width and at a frequency of 30 Hz. To alter skin blood flow, aside from the natural difference in skin blood flow at rest, hot packs and cold packs were used for 5 min. The average fat thickness below the quadriceps and gastrocnemius muscles was 0.75+/-0.13 cm and under the biceps was 0.48+/-0.16 cm. Without the use of hot or cold packs, the currents for the quadriceps and gastrocnemius muscles were significantly higher than that of the biceps (p<0.01). While there was some relationship between stimulation current and blood flow without the application of hot or cold packs, when hot packs were applied, skin blood flow increased as did the current required to stimulate muscle to threshold. When cold packs were applied, there was a decrease in the current required to stimulate these muscles. In conclusion, there is a causal relationship between skin blood flow, the thickness of the fat layer below the skin, and the current required to stimulate the muscle.

The Influence of Environmental Temperature on the Response of the Skin to Local Pressure: the Impact of Aging and Diabetes

Diabetes Technology & Therapeutics. Dec, 2009  |  Pubmed ID: 20001680

To protect against ischemia, pressure-induced vasodilation (PIV) causes an increase in skin blood flow. Endothelial dysfunction, which is commonly found in older patients and those with diabetes, and global temperatures can affect the resting blood flow in skin, which may reduce the blood flow during and after the application of local pressure. The present study investigated the PIV of the skin with exposure to three global temperatures in younger and older populations and those with diabetes.

Multiple Stressors and the Response of Vascular Endothelial Cells: the Effect of Aging and Diabetes

Diabetes Technology & Therapeutics. Feb, 2009  |  Pubmed ID: 19848572

The present study examined the effects of local heat, global heat, and the interaction between these two endothelial stressors on the blood flow of the skin of the foot in people who are older and who have diabetes.

The Combined Effect of a Three-channel Electrode Delivery System with Local Heat on the Healing of Chronic Wounds

Diabetes Technology & Therapeutics. Oct, 2009  |  Pubmed ID: 19821762

Historically, electrical stimulation (ES) has been used as a treatment for wound care. However, some studies show wounds healing with ES, whereas others do not. Part of the difficulty can be resolved by using heat to help dilate blood vessels, but an inherent problem with ES is uneven currents across the wound due to the use of only two electrodes. Therefore, we designed and tested a multi-electrode ES device in combination with local warming of the wound in non-healing chronic ulcers.

Galvanic Skin Resistance--a Marker for Endothelial Damage in Diabetes

Diabetes Technology & Therapeutics. Jul, 2009  |  Pubmed ID: 19580361

Aging and diabetes are both associated with impaired vascular endothelial function. This causes a reduction in the resting blood flow and the blood flow response to autonomic stressors. Further, skin moisture and the ability to sweat are also reduced with aging and diabetes. The present investigation was undertaken to determine if the extent of damage from aging and diabetes could be accurately assessed by simply examining the electrodermal skin response (galvanic skin resistance) to a thermal stress.

The Influence of Age and Diabetes on the Skin Blood Flow Response to Local Pressure

Medical Science Monitor : International Medical Journal of Experimental and Clinical Research. Jul, 2009  |  Pubmed ID: 19564821

Previous data has shown that when pressure is applied to the skin of the ankle and on the foot, there is a reactive increase in circulation. In the present investigation, these studies were expanded to look at the response of the hand, back, and foot to applied pressure.

The Influence of Ageing on the Ability of the Skin to Dissipate Heat

Medical Science Monitor : International Medical Journal of Experimental and Clinical Research. Jun, 2009  |  Pubmed ID: 19478695

Ageing reduces the resting blood flow to the skin as well as the blood flow response to thermal stimuli. However, the interrelationships between skin thickness, subcutaneous fat, and skin blood flow in determining the heat dissipation characteristics of the skin have not been investigated.

A Device to Evaluate Motor and Autonomic Impairment

Medical Engineering & Physics. Jul, 2009  |  Pubmed ID: 19251462

Various devices have been developed to assess impairment of the autonomic nervous system, while other devices have been developed to evaluate the motor system. However, no devices have been developed to examine the interaction between the autonomic and somatic nervous systems. Therefore, the device described here, a square platform which was 0.7x0.7 m in length and 0.1m thick, was developed to examine somatic-autonomic interaction. The device can be used by placing it directly on the floor or on 1 of 2 pivots; one that allowed the platform to move 0.2m (+/-44.1 degrees) in the front to back or side to side direction and one that allowed both movements together. Strain gauge load cells in the platform measured sway and tremor during the subjects attempt to balance and a continuous blood pressure monitor and the ECG were used to assess the response of the autonomic nervous system (heart rate variability). The device was tested on 5 normal subjects and the following was evaluated: (1) sway during standing, (2) weight shift during standing, (3) frequency of sway and extent of sway during standing, (4) sympathetic and parasympathetic alterations in the ANS during attempted balance, and (5) phase delays between motor and autonomic responses. The results showed that, with increasing balance challenge, sway increased, tremor increased, the sway angle increased and sway was positively correlated with heart rate and negatively correlated with blood pressure. A balance challenge significantly increased sympathetic activity but not parasympathetic activity. This device should have useful applications in assessing motor impairments and sensory and autonomic impairments in a variety of conditions.

The Role of Nitric Oxide in Skin Blood Flow Increases Due to Vibration in Healthy Adults and Adults with Type 2 Diabetes

Diabetes Technology & Therapeutics. Jan, 2009  |  Pubmed ID: 19132854

We recently demonstrated concomitant increases in skin blood flow and nitric oxide (NO) production in young healthy adults in response to externally applied vibration of the forearm. Research has shown that adults with type 2 diabetes exhibit depressed NO production and vascular responses to NO. We hypothesized that subjects with type 2 diabetes would display lower than normal increases in skin blood flow to externally applied vibration.

The Effects of Skin Moisture and Subcutaneous Fat Thickness on the Ability of the Skin to Dissipate Heat in Young and Old Subjects, with and Without Diabetes, at Three Environmental Room Temperatures

Medical Engineering & Physics. Mar, 2009  |  Pubmed ID: 18945635

The Pennes model predicts the ability of the skin to dissipate heat as a function of conductive heat transfer and blood flow. Conductive heat exchange may be affected by skin moisture and subcutaneous fat thickness, factors not considered by Pennes. In the present investigation, we sought to expand the Pennes model by examining subcutaneous fat and skin moisture as factors of heat dissipation and their effects on heat exchange and blood flow. Subjects who were older (O) (mean age 64.2+/-5.9 years, n=15), had diabetes (D) (mean age 62+/-5.9 years, mean duration 13.2+/-9.1 years, n=15), and were younger (Y) (mean age 25.7+/-2.9 years, n=15) participated. Thermisters were placed in an iron heat probe and on the skin to measure the change in skin temperature to create a thermal change index to demonstrate the ability of the skin to dissipate heat. The lower back had the thickest subcutaneous fat layer for all subjects, which contributed to higher skin temperatures than the foot and hand in response to local and global heat. There was a significant inverse correlation between skin moisture and skin temperature after 5s of heat application (r=-0.73, p<0.001) with O and D having significantly less skin moisture than Y (p<0.05). O and D had significantly increased skin temperatures in response to local heat, as compared to Y, in all global temperatures (p<0.05). Thus, the Pennes model may need to be adjusted to take into consideration aging, diabetes, skin moisture, and subcutaneous fat thickness.

The Effect of Body Fat, Aging, and Diabetes on Vertical and Shear Pressure in and Under a Waist Belt and Its Effect on Skin Blood Flow

Diabetes Technology & Therapeutics. Feb, 2010  |  Pubmed ID: 20105046

Much attention has been given to the effect of pressure on skin blood flow in the feet of older people and people with diabetes. However, little attention has been paid to other areas of the body, especially under the belt at the waist where pressure might be high during body movements associated with exercise. This may be very important when devices such as heat packs are worn during the day under the belt because their safety relies on appropriate skin blood flow to dissipate the heat; in diabetes populations burns have been seen.

Effects of an Exercise Program on Balance and Trunk Proprioception in Older Adults with Diabetic Neuropathies

Diabetes Technology & Therapeutics. Aug, 2011  |  Pubmed ID: 21561371

Diabetes is the most common cause of peripheral neuropathies. No definitive treatment for diabetic neuropathies has been reported, and very few studies have been published on the role of exercise in reducing either the symptoms or incidence of diabetic neuropathies.

The Use of Thermal Infrared Imaging to Assess the Efficacy of a Therapeutic Exercise Program in Individuals with Diabetes

Diabetes Technology & Therapeutics. Feb, 2012  |  Pubmed ID: 22011006

Abstract Background: Exercise is of great value for individuals with diabetes in helping to control their hemoglobin A1c levels and in increasing their insulin sensitivity. Delayed-onset muscle soreness (DOMS) is a common problem in healthy individuals and in people who have diabetes. People with diabetes are also faced with metabolic and endothelial impairments, which could make DOMS even worse. But because they usually have neuropathies, they may not feel this soreness appropriately, leading to premature return to exercise and causing further injuries. Research Design: One hundred eighteen subjects participated in this study and were divided into four groups. Two groups (healthy and diabetes) performed a series of abdominal exercises, and the other two groups (healthy and diabetes) performed a series of arm exercises to induce DOMS. Skin temperature above the muscle was assessed using a thermal infrared camera, and perceived soreness of the exercised muscle was assessed using a 100-mm visual analog scale. Serum myoglobin concentrations were also measured. Results: There was a significant increase in skin temperature 24 h post-exercise for all four exercise groups (P<0.05), where the combined average increase in skin temperature for all four groups was approximately 0.65°C from baseline. Also, 24 h post-exercise, all four groups were significantly sorer than they were at baseline (P<0.05). Serum myoglobin levels were also significantly higher on day 3 compared with day 1 (P<0.05). Conclusion: Infrared thermal imaging may be a valuable technique of seeing which muscles are sore hours or even days after the exercise is over. Thus, thermal imaging would be an efficient and painless way of looking at DOMS in both healthy individuals and individuals who have diabetes, even if they are facing neurological problems.

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