Foot Conditions and Treatments, Foot Problems

Foot Conditions and Treatments

Painful feet can affect our ability to enjoy the most basic activities in our daily lives. Thankfully, many foot conditions can be easily prevented or treated by wearing properly fitting footwear or using the right over-the-counter foot care products.

Below is a list of common foot conditions. You may read theinformation about the condition that might be causing you pain or other problems, and learn more about treatment and prevention. If your foot pain persists, we recommend that you see your doctor.

Achilles Tendonitis - Definition

Achilles tendonitis causes inflammation and degeneration of the achilles tendon. The achilles tendon is the large tendon located in the back of the leg that inserts into the heel. The pain caused by achilles tendonitis can develop gradually without a history of trauma. The pain can be a shooting pain, burning pain, or even an extremely piercing pain. Achilles tendonitis should not be left untreated due to the danger that the tendon can become weak and ruptured.Achilles Tendonitis is aggravated by activities that repeatedly stress the tendon, causing inflammation. In some cases even prolonged periods of standing can cause symptoms. It is a common problem often experienced by athletes, particularly distance runners. Achilles Tendonitis is a difficult injury to treat in athletes due to their high level of activity and reluctance to stop or slow down their training.Individuals who suffer from achilles tendonitis often complain that their first steps out of bed in the morning are extremely painful. Another common complaint is pain after steps are taken after long periods of sitting. This pain often lessens with activity.

Cause

There are several factors that can cause achilles tendonitis. The most common cause is over-pronation. Over- pronation occurs in the walking process, when the arch collapses upon weight bearing, adding stress on the achilles tendon.Other factors that lead to achilles tendonitis are improper shoe selection, inadequate stretching prior to engaging in athletics, a short achilles tendon, direct trauma (injury) to the tendon, and heel bone deformity.

Treatment and Prevention

Athletes, particularly runners, should incorporate a thorough stretching program to properly warm-up the muscles. They should decrease the distance of their walk or run, apply ice after the activity and avoid any uphill climbs. Athletes should use an orthotic device, heel cup, or heel cradle for extra support.A heel cup or heel cradle elevates the heel to reduce stress and pressure on the achilles tendon. The device should be made with light-weight, shock absorbing materials. An orthotic device can be used to control over-pronation, support the longitudinal arch, and reduce stress on the achilles tendon.

Arch Pain / Arch Strain - Definition

The term arch pain (often referred to as arch strain) refers to an inflammation and/or burning sensation at the arch of the foot.

Cause

There are many different factors that can cause arch pain. A structural imbalance or an injury to the foot can often be the direct cause. However, most frequently the cause is a common condition called plantar fasciitis. The plantar fascia is a broad band of fibrous tissue located along the bottom surface of the foot that runs from the heel to the forefoot. Excessive stretching of the plantar fascia, usually due to over-pronation (flat feet), causes plantar fasciitis. The inflammation caused by the plantar fascia being stretched away from the heel often leads to pain in the heel and arch areas. The pain is often extreme in the morning when an individual first gets out of bed or after a prolonged period of rest. If this condition is left untreated and strain on the longitudinal arch continues, a bony protrusion may develop, known as a heel spur. It is important to treat the condition promptly before it worsens.

Treatment and Prevention

This is a common foot condition that can be easily treated. If you suffer from arch pain avoid high-heeled shoes whenever possible. Try to choose footwear with a reasonable heel, soft leather uppers, shock absorbing soles and removable foot insoles. When the arch pain is pronation related (flat feet), an orthotic designed with a medial heel post and proper arch support is recommended for treating the pain. This type of orthotic will control over-pronation, support the arch and provide the necessary relief.

Arthritis - Definition

Arthritis is a disease characterized by the inflammation of the cartilage and lining of the body's joints. Inflammation causes redness, warmth, pain and swelling.The primary targets for arthritis are people over the age of 50. Arthritis is a major cause of foot pain because each foot has 33 joints that can become affected by the disease.

Osteoarthritis

There are many different types of arthritis. The most common type is called osteoarthritis. Osteoarthritis causes excessive strain and the wearing away of cartilage in the joints of the foot. Movement becomes very difficult and painful. The pain and swelling worsens while standing or walking, and stiffness usually occurs after periods of rest.

Gout

Gout is another form of arthritis that also leads to foot complications. Excess uric acid crystals collect in and around the joints of the big toe. The big toe joint is commonly the focal point due to the stress and pressure it experiences during walking and other weight bearing activities. This often leads to severe pain in the big toe. Men are more likely to develop gouty arthritis than women.

Rheumatoid Arthritis

Another type of arthritis is rheumatoid arthritis. It can develop at any age and there is no known cause for this condition. Rheumatoid arthritis is the most crippling form of the disease that can affect people of all ages. It can cause severe deformities of the joints with associated fatigue of the entire body. People who suffer from rheumatoid arthritis often develop severe forefoot problems such as bunions, hammer toes, claw toes, and others.

Cause

There are many causes of arthritis. Heredity plays a major role. However, arthritic symptoms can develop due to many other factors. Some of these include bacterial and viral infections, prescription and illegal drugs, traumatic injuries, and bowel disorders such as ileitis and colitis.

Forefoot problems such as hammer toes, claw toes, mallet toes, and bunions often develop as a result of arthritis, particularly Rheumatoid arthritis. Problems can also develop in the heel and ankle area due to the erosion of the involved joints.

Treatment and Prevention

Conservative treatment (non-surgical treatment) of the arthritic foot includes proper footwear, orthotics, and/or forefoot supports. Arthritic footwear should provide the following benefits:

High, wide toe box (high and wide space in the toe area)

Removable insoles for fitting flexibility and the option to insert orthotics if necessary.

Rocker Soles designed to facilitate ambulating (walking) and to reduce stress and pain at the ball-of-the-foot.

Arthritic footwear should also accommodate swelling of the foot. Orthotics designed to provide comfort, support and extra cushioning are also recommended. The proper footwear and orthotics will reduce pressure to provide a comfortable and healthy environment for the foot.

Forefoot supports such as gel toe caps, gel toe shields, gel toe straighteners and others can often provide relief. If the problem persists, consult your foot doctor.

Bunions (Hallux Valgus)- Definition

Bunions, referred to in the medical community as Hallux Valgus, are one of the most common forefoot problems. A bunion is a prominent bump on the inside of the foot around the big toe joint. This bump is actually a bone protruding towards the inside of the foot. With the continued movement of the big toe towards the smaller toes, it is common to find the big toe resting under or over the second toe. This causes a common forefoot condition called overlapping toes. Some of the symptoms of bunions include inflammation, swelling, and soreness on the side surface of the big toe. The discomfort commonly causes a patient to walk improperly.

Cause

Bunions are a common problem experienced mostly by women. The deformity can develop from an abnormality in foot function, or arthritis, but is more commonly caused by wearing improper fitting footwear. Tight, narrow dress shoes with a constrictive toe box (toe area) can cause the foot to begin to take the shape of the shoe, leading to the formation of a bunion. Women who have bunions normally wear dress shoes that are too small for their feet. Their toes are squeezed together in their shoes causing the first metatarsal bone to protrude on the side of the foot.

Treatment and Prevention

In the early stages of the formation of a bunion, soaking feet in warm water can provide temporary relief. The best way to alleviate the pain associated with bunions is to wear properly fitting shoes. Shoes designed with a high, wide toe box (toe area) are recommended for people suffering from forefoot disorders, such as bunions. Shoes with rocker soles will unload pressure to the bunion area.

Calluses - Definition

The formation of calluses is caused by an accumulation of dead skin cells that harden and thicken over an area of the foot. This callus formation is the body's defense mechanism to protect the foot against excessive pressure and friction. Calluses are normally found on the ball-of-the-foot, the heel, and/or the inside of the big toe. Some calluses have a deep seated core known as a nucleation. This particular type of callus can be especially painful to pressure. This condition is often referred to as Intractable Plantar Keratosis.

Cause

Calluses develop because of excessive pressure at a specific area of the foot. Some common causes of callus formation are high-heeled dress shoes, shoes that are too small, obesity, abnormalities in the gait cycle (walking motion), flat feet, high arched feet, bony prominences, and the loss of the fat pad on the bottom of the foot.

Treatment and Prevention

Many people try to alleviate the pain caused by calluses by cutting or trimming them with a razor blade or knife. This is not the way to properly treat calluses. This is very dangerous and can worsen the condition resulting in unnecessary injuries. Diabetics especially should never try this type of treatment. To relieve the excessive pressure that leads to callus formation, weight should be redistributed equally with the use of an orthotic. An effective orthotic transfers pressure away from the "hot spots" or high pressured areas to allow the callus to heal. The orthotic should be made with materials that absorb shock and shear (friction) forces. Women should also steer away from wearing high-heeled shoes. As always, surgery should be the very last resort.

Corns - Definition

Corns like calluses develop from an accumulation of dead skin cells on the foot, forming thick, hardened areas. They contain a cone-shaped core with a point that can press on a nerve below, causing pain. Corns are a very common ailment that usually forms on the tops, sides and tips of the toes. Corns can become inflamed due to constant friction and pressure from footwear. Corns that form between the toes are sometimes referred to as soft corns.

Cause

Some of the common causes of corn development are tight fitting footwear, high heeled footwear, tight fitting stockings and socks, deformed toes, or the foot sliding forward in a shoe that fits too loosely. Soft corns result from bony prominences and are located between the toes. They become soft due to perspiration in the forefoot area. Complications that can arise from corns include bursitis and the development of an ulcer.

Treatment and Prevention

There are very simple ways to prevent and treat the corns. You should wear properly fitted footwear with extra room in the toe box (toe area). Avoid shoes that are too tight or too loose. Use an orthotic or shoe insert made with materials that will absorb shock and shear forces. Also avoid tight socks and stockings to provide a healthier environment for the foot. Try to steer away from corn removing solutions and medicated pads. These solutions can sometimes increase irritation and discomfort. Diabetics and all other individuals with poor circulation should never use any chemical agents to remove corns. If the problem persists, consult your foot doctor.

Hammer Toes (Claw Toes) - Definition

A hammer toe is a toe that is contracted at the PIP joint (middle joint in the toe), potentially leading to severe pressure and pain. Ligaments and tendons that have tightened cause the toe's joints to curl downwards. Hammer toes may occur in any toe except the big toe. There is often discomfort at the top part of the toe due to rubbing against the shoe. Hammer toes are classified based on the mobility of the toe joints. There are two types - flexible and rigid. In a flexible hammer toe, the joint has the ability to move. This type of hammer toe can be straightened manually. A rigid hammer toe does not have that same ability to move. Movement is very limited and can be extremely painful. This sometimes causes foot movement to become restricted leading to extra stress at the ball-of-the-foot, and possibly causing pain and the development of corns and calluses. Follow this link to learn more about hammer toe products.

Cause

Hammer toes result from a muscle imbalance which causes the ligaments and tendons to become unnaturally tight. This results in the joint curling downward. Arthritis can also lead to many different forefoot deformities, including hammer toes.

Treatment and Prevention

Changing the type of footwear worn is a very important step in the treatment of hammer toes. When choosing a shoe, make sure the toe box (toe area) is high and broad, and can accommodate the hammer toes. A shoe with a high, broad toe box will provide enough room in the forefoot area so that there is less friction against the toes. Other conservative treatments include using forefoot products designed to relieve hammer toes, such as hammer toe crests and hammer toe splints. These devices will help hold down the hammer toe and provide relief to the forefoot. Gel toe shields and gel toe caps are also recommended to eliminate friction between the shoe and the toe, while providing comfort and lubrication.

Heel Fissures (Cracked Heels) - Definition

Heel fissures, also known as cracked heels can be a simple cosmetic problem and a nuisance, but can also lead to serious medical problems. Heel fissures occur when the skin on the bottom, outer edge of the heel becomes hard, dry and flaky, sometimes causing deep fissures that can be painful or bleed.

Cause

Heel fissures can affect anyone, but risk factors include: Living in a dry climate Obesity Consistently walking barefoot or wearing sandals or open-backed shoes Inactive sweat glands like many foot conditions, heel fissures can become more dangerous if they go untreated and become deep or infected. This is especially dangerous for people with diabetes or compromised immune systems.

Treatment and Prevention

Moisturizing the feet regularly can prevent heel fissures. Once they occur, you can use a pumice stone daily to gently decrease the thick and flaky layer of skin. Avoid going barefoot or wearing open-backed shoes, sandals or shoes with thin soles. Shoes with strong shock absorption can help to improve the condition. Moisturizing the feet at least twice a day and wearing socks over moisturizer while sleeping can also help. If the problem persists, see your foot doctor.

Heel Pain - Definition

Heel pain is a common condition in which weight bearing on the heel causes extreme discomfort.

Cause

There are two different categories of heel pain. The first is caused by over-use repetitive stress which refers to a soreness resulting from too much impact on a specific area of the foot. This condition, often referred to as "heel pain syndrome," can be caused by shoes with heels that are too low, a thinned out fat pad in the heel area, or from a sudden increase in activity. Plantar fasciitis, a very common diagnosis of heel pain, is usually caused from a biomechanical problem, such as over-pronation (flat feet). The plantar fascia is a broad band of fibrous tissue that runs along the bottom surface of the foot, from the heel through the midfoot and into the forefoot. Over-pronation can cause the plantar fascia to be excessively stretched and inflamed, resulting in pain in the heel and arch areas of the foot. Often the pain will be most intense first thing in the morning or after a prolonged period of rest. The pain will gradually subside as the day progresses.

Treatment and Prevention

To properly treat heel pain, you must absorb shock, provide cushioning and elevate the heel to transfer pressure. This can be accomplished with a heel cup, visco heel cradle, or an orthotic designed with materials that will absorb shock and shear forces. When the condition is pronation related (usually plantar fasciitis), an orthotic with medial posting and good arch support will control the pronation and prevent the inflammation of the plantar fascia. Footwear selection is also an important criteria when treating heel pain. Shoes with a firm heel counter, good arch support, and appropriate heel height are the ideal choice. If the problem persists, consult your foot doctor.

Mallet Toes - Definition

Cause

Many disorders can affect the joints in the toes, causing pain and preventing the foot from functioning as it should. A mallet toe occurs when the joint at the end of the toe cannot straighten. Excessive rubbing of the mallet toe against the top of the shoe can lead to pain and the development of a corn. The tip of the toe is often turned down against the shoe causing pressure and discomfort. Arthritis can also lead to many forefoot deformities including mallet toes. Mallet toes can cause extreme discomfort, and can be aggravated if restrictive or improperly fitting footwear is worn for a prolonged period of time.

Treatment and Prevention

Any forefoot problems that cause pain or discomfort should be given prompt attention. Ignoring the symptoms can aggravate the condition and lead to a breakdown of tissue, or possibly even infection. Conservative treatment of mallet toes begins with accommodating the deformity. The goal is to relieve pressure, reduce friction, and transfer forces from the sensitive areas. Shoes with a high and broad toe box (toe area) are recommended for people suffering from forefoot deformities such as mallet toes. This prevents further irritation in the toe area from developing. Other conservative treatment includes forefoot supports such as gel toe caps, gel toe shields and toe crests. Gel forefoot supports provide immediate comfort and relief from common forefoot disorders without drying the skin.

Over Pronation (Flat Feet) - Definition

Over-pronation, or flat feet, is a common biomechanical problem that occurs in the walking process when a person's arch collapses upon weight bearing. This motion can cause extreme stress or inflammation on the plantar fascia, potentially causing severe discomfort and leading to other foot problems.

Cause

Over-pronation is very prominent in people who have flexible, flat feet. The framework of the foot begins to collapse, causing the foot to flatten and adding stress to other parts of the foot. As a result, over-pronation, often leads to Plantar Fasciitis, Heel Spurs, Metatarsalgia, Post-tib Tendonitis and/or Bunions. There are many causes of flat feet. Obesity, pregnancy or repetitive pounding on a hard surface can weaken the arch leading to over-pronation. Often people with flat feet do not experience discomfort immediately, and some never suffer from any discomfort at all. However, when symptoms develop and become painful, walking becomes awkward and causes increased strain on the feet and calves.

Treatment and Prevention

Over-Pronation can be treated conservatively (non-surgical treatments) with over-the-counter orthotics. These orthotics should be designed with appropriate arch support and medial rearfoot posting to prevent the over-pronation. Footwear should also be examined to ensure there is a proper fit. Footwear with a firm heel counter is often recommended for extra support and stability. Improperly fitting footwear can lead to additional foot problems. If the problem persists, consult your foot doctor.

The Diabetic Foot - Definition

Diabetes is a serious disease that can develop from lack of insulin production in the body or due to the inability of the body's insulin to perform its normal everyday functions. Insulin is a substance produced by the pancreas gland that helps process the food we eat and turn it into energy. Diabetes affects approximately 16 million Americans and is classified into 2 different types: Type 1 and Type 2. Type 1 is usually associated with juvenile diabetes and is often linked to heredity. Type 2, commonly referred to as adult onset diabetes, is characterized by elevated blood sugars, often in people who are overweight or have not attended to their diet properly. Many complications can be associated with diabetes. Diabetes disrupts the vascular system, affecting many areas of the body such as the eyes, kidneys, legs, and feet. People with diabetes should pay special attention to their feet.

Neuropathy

Of the sixteen million Americans with diabetes, 25% will develop foot problems related to the disease. Diabetic foot conditions develop from a combination of causes including poor circulation and neuropathy. Diabetic Neuropathy can cause insensitivity or a loss of ability to feel pain, heat, and cold. Diabetics suffering from neuropathy can develop minor cuts, scrapes, blisters, or pressure sores that they may not be aware of due to the insensitivity. If these minor injuries are left untreated, complications may result and lead to ulceration and possibly even amputation. Neuropathy can also cause deformities such as Bunions, Hammer Toes, and Charcot Feet. It is very important for diabetics to take the necessary precautions to prevent all foot related injuries. Due to the consequences of neuropathy, daily observation of the feet is critical. When a diabetic patient takes the necessary preventative footcare measures, he or she reduces the risks of serious foot conditions.

Poor Circulation

Diabetes often leads to peripheral vascular disease that inhibits a person's blood circulation. With this condition, there is a narrowing of the arteries that frequently leads to significantly decreased circulation in the lower part of the legs and the feet. Poor circulation contributes to diabetic foot problems by reducing the amount of oxygen and nutrition supplied to the skin and other tissue, causing injuries to heal poorly. Poor circulation can also lead to swelling and dryness of the foot. Preventing foot complications is more critical for the diabetic patient because poor circulation impairs the healing process and can lead to ulcers, infection, and other serious foot conditions.

Treatment and Prevention

Footwear and orthotics play an important role in diabetic foot care. Diabetic footwear should also provide the following protective benefits:

High, wide toe box (high and wide space in the toe area)

Removable insoles for fitting flexibility and the option to insert orthotics if necessary.

Rocker Soles designed to reduce pressure in the areas of the foot most susceptible to pain, most notably the ball-of-the-foot.

Firm Heel Counters for support and stability.

If you are a diabetic, you should be particularly alert to any problems you may be having with your feet. It is very important for diabetics with neuropathy to take necessary precautions to prevent injury and keep their feet healthy. If you have diabetes and are experiencing a foot problem, immediately consult your foot doctor.

Foot care & Diabetes

Proper foot care is especially critical for diabetics because they are prone to foot problems such as:

Loss of feeling in their feet

Changes in the shape of their feet

Foot ulcers or sores that do not heal

Simple daily foot care can prevent serious problems. According to the National Institute of Health, the following simple everyday steps will help prevent serious complications from diabetes:

1. Take Care of Your Diabetes

Make healthy lifestyle choices to keep your blood sugar close to normal. Work with your health care team to create a diabetes plan that fits your lifestyle characteristics.

2. Check Your Feet Every Day

You may have foot problems that you may not be aware of. Check your feet for cuts, sores, red spots, swelling, or infected toenails. Checking your feet should become part of your daily routine. If you have trouble bending over to see your feet, use a plastic mirror to help. You can also ask a family member to help you. Important Reminder: Be sure to call your doctor immediately if a cut, sore, blister, or bruise on your foot does not heal after one day.

3. Wash Your Feet Every Day

Wash your feet in warm, NOT HOT, water. Do not soak your feet because your skin will get dry. Before bathing or showering, test the water to make sure it is not too hot. You should use a thermometer or your elbow. Dry your feet well. Be sure to dry between your toes. Use talcum powder to keep the skin dry between the toes.

4. Keep the Skin Soft and Smooth

Rub a thin coat of skin lotion or cream on the tops and bottoms of the feet. Do not put lotion between your toes, because this might cause infection.

5. Wear Shoes and Socks At All Times

Wear shoes and socks at all times. Do not walk barefoot, not even indoors. It is extremely easy to step on something and hurt your feet. Always wear seamless socks, stockings, and nylons with your shoes to help avoid the possibility of blisters and sores developing. Be sure to choose seamless socks that are made of materials that wick moisture away from your feet and absorb shock and shear. Socks made of these materials help keep your feet dry. Always check the insides of your shoes before putting them on. Make sure the lining is smooth and there are no foreign objects in the shoe, such as pebbles. Wear shoes that fit well and protect your feet.

6. Protect Your Feet From Hot and Cold

Always wear shoes at the beach or on hot pavement. Put sunscreen on the tops of your feet for protection from the sun. Keep your feet away from radiators or open fires. DO NOT use hot water bottle or heating pads on your feet. If your feet are cold, wear seamless socks at night. Lined boots are good to keep your feet warm in the winter. Choose socks carefully. DO NOT wear socks with seams or bumpy areas. Choose padded socks to protect your feet and make walking more comfortable. In cold weather, check your feet often to keep your feet warm avoid frostbite.

7. Keep the Blood Flowing to Your Feet

Put your feet up when you are sitting. Wiggle your toes for 5 minutes, 2 or 3 times a day. Move your ankles up and down and in and out to improve blood flow in your feet and legs.

DO NOT cross your legs for long periods of time.

DO NOT wear tight socks, elastic, or rubber bands, or garters around your legs.

DO NOT wear restrictive footwear or foot products. Foot products that can cut off circulation to the feet, such as products with elastic, should not be worn by diabetics.

DO NOT smoke. Smoking reduces blood flow to your feet. If you have high blood pressure or high cholesterol, work with your health care team to lower it.

8. Be More Active

Ask your doctor to plan an exercise program that is right for you. Walking, dancing, swimming, and bicycling are good forms of exercise that are easy on the feet. Avoid all activities that are hard on the feet, such as running and jumping. Always include a short warm-up or cool-down period. Wear protective walking or athletic shoes that fit well and offer good support.

If the problem persists, consult your foot doctor.

Foot Facts

A quarter of all the body’s bones are in the feet (There are 52 bones in a pair of feet).

During the first year of a child’s life their feet grow rapidly, reaching almost half their adult size. By 12, a child’s foot is about 90 per cent of its adult length.

When walking, each time your heel lifts off the ground it forces the toes to carry one half of your body weight.

In a pair of feet, there are 250,000 sweat glands.

Cigarette smoking is the biggest cause of Peripheral Vascular Disease (disease of the arteries of the feet and legs) which often leads to pain on walking, ulceration, infection and in the most severe cases - gangrene and possible amputation.

Foot disorders in the elderly are extremely common and are the cause of much pain and disability, and consequent loss of mobility and independence.

A human foot & ankle is a strong, mechanical structure that contains 26 bones, 33 joints, and more than 100 muscles, tendons & ligaments.

During an average day of walking, the total forces on your feet can total hundreds of tons, equivalent to an average of a fully loaded cement truck.

Walking is the best exercise for your feet. It contributes to your general health by improving circulation and weight control.

Standing in one spot is far more tiring than walking because the demands are being made on the same few muscles for a longer length of time.

Your feet mirror your general health.Foot ailments can become your first sign of more serious medical problems. Your feet mirror your general health, so conditions like arthritis, diabetes, nerve and circulatory disorders can show their initial symptoms in your feet.

The average person takes 8,000 to 10,000 steps a day, will walk around 115,000 miles in a life time, that's more than four times around the earth!

The foot contains 26 bones, 33 joints, 107 ligaments and 19 muscles.

1/4 of all the bones in the human body are down in your feet. When these bones are out of alignment, so is the rest of the body.

Only a small percentage of the population is born with foot problems. It's neglect and a lack of awareness of proper care - including ill fitting shoes - that bring on problems.

Women have about four times as many foot problems as men. High heels are partly to blame.

Walking is the best exercise for your feet. It also contributes to your general health by improving circulation, contributing to weight control, and promoting all-around well being.

Arthritis is the number one cause of disability. It limits everyday dressing, climbing stairs, getting in and out of bed or walking

There are 250,000 sweat glands in a pair of feet. Sweat glands in the feet excrete as much as a half-pint of moisture a day.

The two feet may be different sizes. Buy shoes for the larger one. It’s rare that two feet are exactly the same; one of them is often larger than the other

The pressure on the feet when running can be as much as four times the runners body weight.