Vertebral lumbar pain: multifactorial origin, symptomatology, treatment principles

Lumbar radiculopathy (radicular syndrome) is a neurological condition caused by compression of one of the L1-S1 roots, which is characterized by low back pain radiating to the leg. Compression of the root can be manifested not only by pain (sometimes of a shooting nature), but also by impaired sensitivity, numbness, paresthesia or muscle weakness. Radiculopathy (radicular syndrome) can occur in any part of the spine, but it most often occurs in the lumbar region. Lumbosacral radiculopathy occurs in approximately 3-5% of the population, in both men and women, but, as a rule, the syndrome occurs in men at the age of 40 years, and in women the syndrome develops between the ages of 50 and 60 years. Treatment of radicular syndrome of the lumbosacral spine can be carried out using both conservative methods and surgical techniques.

Causes

Any morphological formations or pathological processes that lead to compression effects on the nerve root can cause radicular syndrome.

The main causes of lumbar radiculopathy are:

• A disc herniation or bulge can put pressure on the nerve root and lead to inflammation in the root area.
• A degenerative disease of the joints of the spine that results in the formation of bone spurs on the facet joints, which can lead to a narrowing of the intervertebral space, which will put compression on the nerve roots.
• Trauma or muscle spasm can put pressure on the root and cause symptoms in the area of ​​innervation.
• Degenerative disc disease, which leads to wear and tear of the intervertebral disc structure, and a decrease in the height of the discs, which can lead to a decrease in the free space in the intervertebral foramen and compression of the root as it exits the spinal column.
• Spinal stenosis
• Tumors
• Infections or systemic diseases

In patients under 50 years of age, the most common cause of radicular syndrome in the lumbar spine is a herniated disc. After 50 years of age, radicular pain is often caused by degenerative changes in the spine (stenosis of the intervertebral foramen).

Risk factors for developing lumbar radiculopathy:

• age (45-64 years)
• smoking
• mental stress
• Strenuous physical activity (frequent heavy lifting)
• Driving or vibration exposure

Symptoms

Symptoms resulting from radicular syndrome (radiculopathy) are localized in the area of ​​innervation of a particular root.

• Back pain radiating to the buttock, leg and extending down behind the knee, into the foot - the intensity of the pain depends on the root and the degree of compression.
• Disruption of normal reflexes in the lower limb.
• Numbness or paresthesia (tingling) may occur from the lower back to the foot, depending on the area of ​​innervation of the affected nerve root.
• Muscle weakness can occur in any muscle innervated by a pinched nerve root. Prolonged pressure on a nerve root can cause atrophy or loss of function of a specific muscle.
• Pain and local tenderness are localized at the level of the damaged root.
• Muscle spasm and postural changes in response to root compression.
• Pain increases with exercise and decreases with rest
• Loss of the ability to make certain movements of the body: inability to straighten back, bend towards the localization of compression, or stand for a long time.
• If the compression is significant, activities such as sitting, standing and walking may be difficult.
• Change in normal lordosis of the lumbar spine.
• Development of stenosis-like symptoms.
• Stiffness in the joints after a period of rest.

Patterns of pain

• L1 - back, front and inner surface of the thigh.
• L2 - back, front and inner surface of the thigh.
• L3 - back and front, and the inner surface of the thigh with a downward extension.
• L4 - back and front of the thigh, to the inner surface of the leg, into the foot and big toe.
• L5 – Along the posterolateral part of the thigh, the front part of the lower leg, the top of the foot and the middle toe
• S1 S2 – Buttock, back of the thigh and lower leg.

The onset of symptoms in patients with lumbosacral radiculopathy (radicular syndrome) is often sudden and includes low back pain.

Sitting, coughing or sneezing can aggravate the pain, which radiates from the buttock down the back of the leg, ankle or foot.

You need to be vigilant for certain symptoms (red flags). These red flags may indicate a more serious condition that requires further evaluation and treatment (eg, tumor, infection). The presence of fever, weight loss, or chills requires careful evaluation.

The patient's age is also a factor when looking for other possible causes of the patient's symptoms. People under 20 years of age and over 50 years of age are at increased risk for more serious causes of pain (eg, tumors, infections).

Vertebral lumbar pain: multifactorial origin, symptomatology, treatment principles

Back pain, familiar to almost every person, is most often associated with damage to the lumbosacral spine. The development of chronic vertebral pain, including lumbar pain, is facilitated by heavy physical exertion and, conversely, by the lack of adequate exercise, unfavorable meteorological factors (especially permanent ones associated with unsatisfactory working and living conditions), congenital or acquired pathology of the musculoskeletal system and spinal column, and also the presence of excess weight and osteoporosis. In terms of its prevalence in our country, chronic vertebral pain is one of the mass public health problems.

Lumbar vertebral pain, in addition to primary damage to the spine, can have an “extravertebral” origin - due to secondary involvement of the osteochondral and nervous structures of the spinal column.

Main factors and clinical forms of spinal lesions

The primary factors of damage to the spine - in particular, its lumbosacral region - include focal or widespread vertebral changes associated with independently occurring pathology of the spinal column. Among them, the main factor is the dystrophic vertebral process (osteochondrosis of the spine).

Secondary damage factors are associated with the presence of an extravertebral pathological process, which also leads to the development of focal or widespread changes in the spine. Among them, osteoporosis and metastatic lesions of the spine are of greatest clinical importance.

The first factor (osteoporosis) is highly prevalent among middle-aged, elderly and senile women. At the same time, spinal osteoporosis most often occurs without the development of neurological disorders, and therefore its clinical manifestations are rarely a reason for neurological observation. The second factor (metastatic lesions) is many times higher than the incidence of primary spinal tumors. In some cases, vertebral disorders of metastatic origin come under the supervision of a neurologist even before the diagnosis of the underlying disease is made. The diagram - factors and clinical forms of primary and secondary spinal lesions - is presented on

.

Clinical manifestations of pathology of the lumbosacral spine

In neurological practice, differentiation of forms of vertebral lesions begins with the definition of vertebral syndrome, taking into account the characteristics of which the underlying disease is established. Clinical manifestations of pathology of the lumbosacral spine represent 3 groups of vertebral syndromes (

):

• actually painful;
• radicular monoradicular;
• polyradicular.

Pain (reflex) syndromes

Painful (reflex) syndromes of the lumbosacral region, not accompanied by focal neurological symptoms, can manifest themselves:

• lumbodynia - acute, subacute or chronic pain in the lumbosacral region (Fig. 3), in some cases - lumbago (sharp, sudden lumbar pain - “lumbago”);
• lumboischialgia - lumbar pain radiating along the dermatome of the sciatic nerve - n. ischiadicus (Fig. 3);
• coccydynia—pain in the coccyx area (Fig. 3).

Radicular syndromes (radiculopathies)

Radicular syndromes (radiculopathies) caused by damage to the lumbosacral spine are less common than lumbar pain syndromes. The presence of radiculopathy is indicated by symptoms of loss of sensitive, reflex and motor functions of a certain spinal root.

Manifestations of lumbosacral radiculopathy:

1. pain in the lumbar region, radiating to the leg (down to the foot);
2. hyperesthesia or paresthesia (tingling sensation, crawling “goosebumps”) - mainly in the area of ​​pain;
3. hypoesthesia/hypalgesia - mainly in the distal innervation of the root (outer/inner edge of the foot);
4. asymmetry (due to decreased) or absence of Achilles and knee reflexes;
5. decreased muscle strength—mainly in the extensor and flexor muscles of the toes.

The most common forms of lumbosacral radiculopathies are associated with damage to the fifth lumbar (L5) and first sacral (S1) spinal roots. Clinical differences between these radiculopathies relate to the areas of localization of pain and sensory disorders, as well as the presence of the Achilles reflex, which disappears with S1 radiculopathy (Fig. 4).

Clinical features of spinal osteochondrosis

In the vast majority of cases, the development of lumbar pain and radicular syndromes is caused by spinal osteochondrosis, especially often affecting the joints of the two lower lumbar vertebrae and the base of the sacrum (intervertebral discs LIV-LV, LV-SI).

The main clinical manifestations of spinal osteochondrosis, which limit the patient's motor activity to varying degrees, include recurrent or chronic vertebral pain, painful spinal mobility, as well as monoradicular neurological disorders.

The course of clinical manifestations of spinal osteochondrosis is most often cyclical - with alternating periods of exacerbation and remission (complete or partial). Exacerbations are usually seasonal (autumn and spring). The highest frequency of exacerbations of the disease occurs in the fifth decade of life. In most cases, the development of exacerbations of vertebral pathology is predictable - in case of violation of the regime that limits physical activity and excludes cooling.

The most characteristic clinical feature of spinal osteochondrosis as a disease with a chronic, long-term course is the inevitability of a gradual “subsidence” of vertebral pain (usually at the turn of the 5th–6th decades of life). This feature of spinal osteochondrosis is due to the transition of the current degenerative process to the final stage, stabilizing the position of the bone and soft tissue structures of the spinal column. In this regard, regression of vertebral pain is often accompanied by an even greater limitation of spinal mobility. Pain and limitations in the patient’s daily physical activity that persist after 50 years are most often associated with a previous injury, another form of spinal damage, or osteoarthritis of the hip joint.

The most unfavorable form of manifestation of lumbar osteochondrosis is the development of discogenic compression of the structures of the spinal canal, in particular the cauda equina, which threatens severe neurological complications and disability of the patient. Compression of the spinal canal structures may also be associated with secondary forms of spinal damage ().

Signs of acute compression of the spinal canal structures (including the cauda equina):

• the occurrence of bilateral weakness and numbness of the legs, numbness in the perineum;
• retention of urine and feces;
• with compression (compression-ischemic) damage to the spinal cord—spontaneous reduction of pain, followed by a feeling of numbness of the pelvic girdle and limbs.

Clinical features of secondary spinal lesions

Symptomatic vertebral pain caused by secondary damage to the spine, at the very beginning of its development, can occur similar to manifestations of spinal osteochondrosis. The presence of this pain often becomes the reason for physiotherapy, which can further aggravate the manifestations of the underlying disease.

Establishing the symptomatic nature of vertebral pain is facilitated by:

• a thorough analysis of the patient’s complaints during “chronization” and increasing intensity of vertebral pain, as well as its atypical manifestations;
• clinical examination of the patient if the treatment is insufficiently effective.

Atypical vertebral manifestations (characteristic of secondary spinal lesions):

• vertebral pain:

–more often occurs in patients over 40, especially 50 years old; – gradually increases; – intensifies with movement, persists or intensifies at rest; – daytime, as well as nighttime, including “awakening”; – accompanied by local vertebral pain - “soreness” or sharp pain within one or two adjacent vertebrae when pressing and “tapping” the spinous processes;

• the effectiveness of non-narcotic analgesics: in usual therapeutic doses - short-term, gradually decreasing;
• the presence of extravertebral pain - paravertebral, abdominal, lower abdomen or groin area;
• combination with somatic disorders:

– increased body temperature; – general weakness, loss of appetite, loss of body weight; – changes in laboratory parameters—acceleration of ESR, anemia, leukocytosis.

Principles of treatment

Analgesics

The main analgesic drugs for eliminating vertebral pain are non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs, like other painkillers, are usually self-administered by patients when pain intensifies and returns. However, long-term use of analgesics, which increases the risk of complications of drug therapy, requires the use of NSAIDs under medical supervision.

Today, in the arsenal of a practicing physician there is a wide range of NSAIDs, which, according to their mechanism of action, belong to “non-selective” anti-inflammatory drugs - blocking the enzyme cyclooxygenase (COX) and “selective” - blocking the COX-2 isoenzyme. These drugs differ significantly in the ratio of advantages and disadvantages, respectively, in the severity and duration of therapeutic effects and the side effects caused. Probably more preferable for patients with vertebral pain (in terms of availability, effectiveness and lower likelihood of side effects) are: among the “non-selective” NSAIDs - diclofenac, ibuprofen and ketoprofen, and among the “selective” - meloxicam.

Methods of using NSAIDs:

Diclofenac - orally 100-150 mg/day (regular tablet forms 25-50 mg, retard form - 100 mg); intramuscularly or subcutaneously; rectally; locally.

Ibuprofen - orally 1200 mg/day; locally.

Ketoprofen - orally 150–300 mg/day (regular tablet form 50 mg, retard form 150 mg); intramuscularly; rectally; locally.

Meloxicam—orally 7.5–15 mg/day (once); intramuscularly; rectally.

The general rule for NSAIDs is to take the oral form during or immediately after a meal with plenty of water.

The duration of NSAID use depends on the severity and duration of vertebral pain. For acute back pain, short-term (several days) use of NSAIDs is sufficient. In the presence of intense, especially radicular pain, the period of use of the same NSAID is usually at least 3–4 weeks.

The most likely side effects of NSAIDs are related to their effects on the gastrointestinal tract. A lower incidence of gastric and intestinal dyspepsia, as well as gastrointestinal bleeding, is observed with the use of meloxicam.

B vitamins

The use of neurotropic B vitamins is a common method in clinical practice for the treatment of patients with damage to the peripheral nervous system, including neurological manifestations of spinal osteochondrosis. To carry out the so-called vitamin therapy, the method of alternately administering solutions of thiamine (vitamin B1), pyridoxine (vitamin B6) and cyanocobalamin (vitamin B12) - 1-2 ml intramuscularly with daily alternation of each drug - for 2-4 weeks was traditionally used. The disadvantages of this scheme have long been known - small doses and frequent injections lead to low compliance.

Currently, the multicomponent drug “Milgamma” is more often used, each ampoule of which contains 100 mg of thiamine and pyridoxine and 1000 mcg of cyanocobalamin, as well as lidocaine, which provides a local anesthetic effect when administered intramuscularly. Milgamma, which has an antinociceptive (probably serotonergic) effect, is used for acute, recurrent and chronic vertebral pain. Due to the established influence of Milgamma on the processes of regeneration of nerve fibers and the myelin sheath, this drug is especially widely used in vertebral and extravertebral forms of damage to the peripheral nervous system.

Milgamma compositum - for oral administration, includes benfotiamine (a fat-soluble form of vitamin B1 that retains its pharmacological activity after absorption in the gastrointestinal tract) and pyridoxine. The presence of these two components ensures the effectiveness of further therapy (within 6 weeks, after a course of use of the drug "Milgamma".

Treatment regimen:

Milgamma - 2 ml intramuscularly, daily, for 10 or 15 days.

Milgamma compositum - orally, 1 tablet 3 times a day, for 6 weeks.

Non-drug treatments

In case of exacerbation of vertebral pain and its reverse development, along with drug treatment, physiotherapy (including massage), acupuncture and manual therapy are carried out alternately and in different sequences. At the same time, gradual motor activation, which does not increase the severity of pain, should be carried out, which is an effective method of “self-help” for the patient, and, without exacerbation, a method of preventing chronic vertebral pain.

Surgical methods of treatment

Surgical methods for treating vertebral pathology can be planned or emergency. The planned procedure for surgical intervention is determined by a relatively stable clinic of vertebral pathology, requiring radical removal or accessible for surgical intervention.

The purpose of such operations (at the lumbar level) is:

• decompression of the spinal roots in case of discogenic compression or spinal canal stenosis;
• removal of a tumor of the spine, spinal cord, spinal membrane or root, which is not accompanied by signs of increasing compression.

Most spinal surgeries are performed for chronic or frequently recurring low back pain. The main argument in favor of choosing surgical treatment is usually the “exhaustion” of the entire arsenal of conservative methods available for a given case.

When making a decision to undergo surgical treatment - radical, but much more expensive - it is necessary to take into account:

1. a certain likelihood of resumption of vertebral pain (including in the area of ​​other vertebrae) after surgery;
2. the possibility of gradual spontaneous weakening and even complete regression of vertebral pain without surgical intervention;
3. a significant dependence of the results of surgical treatment, even methodically successful operations, on the premorbid status of the patient: postoperative persistence and resumption of vertebral pain is typical for patients with hypochondriacal and depressive disorders, alcohol addiction, as well as those with concomitant somatic pathology.

The need for emergency surgical intervention arises with the acute development of neurological disorders caused by compression of the spinal cord and cauda equina. In the absence of radical treatment, against the background of a further increase in spinal and polyradicular symptoms, the development of irreversible neurological disorders is possible. However, an emergency surgical operation can eliminate acute compression of the spinal cord, its vessels and the cauda equina, and ensure the restoration of motor, sensory and pelvic functions.

Yu. V. Grachev, Doctor of Medical Sciences V. I. Shmyrev, Doctor of Medical Sciences, Professor of the Scientific Research Institute of Advanced Promotion of the Russian Academy of Medical Sciences, MC Administrative Center of the President of the Russian Federation, Moscow

Diagnostics

The primary diagnosis of radicular syndrome of the lumbosacral spine is made based on the symptoms of the medical history and physical examination (including a thorough examination of the neurological status). A thorough analysis of motor, sensory and reflex functions allows us to determine the level of damage to the nerve root.

If the patient reports typical unilateral radiating leg pain and there are one or more positive neurological test results, then a diagnosis of radiculopathy is very likely.

However, there are a number of conditions that may present with similar symptoms. Differential diagnosis must be carried out with the following conditions:

• Pseudoradicular syndrome
• Traumatic disc injuries in the thoracic spine
• Damage to discs in the lumbosacral region
• Spinal stenosis
• Cauda equina
• Spinal tumors
• Spinal infections
• Inflammatory/metabolic causes - diabetes, ankylosing spondylitis, Paget's disease, arachnoiditis, sarcoidosis
• Trochanteric bursitis
• Intraspinal synovial cysts

To make a clinically reliable diagnosis, as a rule, instrumental diagnostic methods are required:

• X-rays – can detect the presence of joint degeneration, fractures, bone defects, arthritis, tumors or infections.
• MRI is a valuable technique for visualizing morphological changes in soft tissues, including discs, spinal cord and nerve roots.
• CT (MSCT) provides complete information about the morphology of the bone structures of the spine and visualization of spinal structures in cross section.
• EMG (ENMG) Electrodiagnostic (neurophysiological) studies are necessary to exclude other causes of sensory and motor disorders, such as peripheral neuropathy and motor neuron disease

Types of lower back pain

Understanding the nature of the pain is very important, because this will help the doctor immediately make an assumption about the diagnosis and prescribe a more accurate diagnosis.

Pain happens:

• acute (occurs due to recent damage, lasts up to 1.5 months);
• aching;
• blunt;
• strong and long lasting;
• subacute (lasts 6-12 weeks);
• variable (transitory);
• chronic (lasts more than 12 weeks).

Low back pain is also divided into primary and secondary.

Primary

associated with chronic changes in the tissues of the spine and muscles. Sometimes the spinal roots are involved in the process.

Secondary

pain indicates another disease. This could be arthrosis, arthritis, or some pathology of the internal organs.

Conservative treatment:

• Rest: avoid activities that cause pain (bending, lifting, twisting, turning or bending backwards. Rest is necessary for acute pain syndrome
• Drug treatment: anti-inflammatory, painkillers, muscle relaxants.
• Physiotherapy. For acute pain syndrome, the use of procedures such as cryotherapy or chivamat is effective. Physiotherapy can reduce pain and inflammation of the spinal structures. After the acute period has stopped, physiotherapy is carried out in courses (ultrasound, electrical stimulation, cold laser, etc.).
• Corseting. The use of a corset is possible in case of acute pain syndrome to reduce the load on the nerve roots, facet joints, and lumbar muscles. But the duration of wearing a corset should be short, since prolonged fixation can lead to muscle atrophy.
• Epidural steroid injections or facet joint injections are used to reduce inflammation and control pain in severe radicular syndrome.
• Manual therapy. Manipulations can improve the mobility of the motor segments of the lumbar spine and relieve excess muscle tension. Using mobilization techniques also helps modulate pain.
• Acupuncture. This method is widely used in the treatment of radicular syndrome in the lumbosacral spine and helps both reduce symptoms in the acute period and is included in the rehabilitation complex.
• Exercise therapy. Exercise includes stretching and strengthening exercises. The exercise program allows you to restore joint mobility, increase range of motion and strengthen your back and abdominal muscles. A good muscle corset allows you to support, stabilize and reduce tension on the spinal joints, discs and reduce the compression effect on the spine. The volume and intensity of exercise should be increased gradually to avoid relapse of symptoms.

• In order to achieve stable remission and restore full functionality of the spine and motor activity, it is necessary for the patient, after completing the course of treatment, to continue independent exercises aimed at stabilizing the spine. The exercise program must be individual.

How to quickly get rid of pain without drugs and at home

You won’t be able to get rid of pain in a minute, but in 5-10 it’s quite possible. To do this, you need to do an exercise aimed at relieving muscle spasm and relaxing the lumbar region.

We offer two options:

Exercise one

• Starting position: kneeling.
• The right leg should be bent at a right angle, it should stand in front. With your left foot, place your knee on the floor.
• In this position you need to find balance and fixate.
• When you succeed, reach back with your left hand and grab your left foot.
• After this, pull your left leg by the heel to the pelvis. The thigh muscles should be well stretched. You can enhance the effect by squeezing your left buttock.
• Stay in this position for half a minute, then slowly and carefully lower your left leg, returning to the starting position.
• After this, do the exercise for your right leg.

Exercise two (you will need a massage roller)

• Lie on your back with a massage roller under your sacrum. Important: do not place the roller under your spine under any circumstances.
• Gently pull your right knee toward your chest. The left heel should touch the floor. At this moment, you will feel the anterior thigh muscle stretch.
• To increase muscle tension, place your left hand behind your head and turn your bent knee slightly to the right.
• Hold this position for half a minute.
• Repeat the exercise for the other leg.

Other home remedies for lower back pain

If the pain is caused by swelling, a dry cold compress can help. Take ice or something frozen from the freezer, put it in a bag and wrap it in a cloth. Apply to the lower back for 20 minutes for two days. You can repeat every two hours.

If the pain does not go away from the cold, then after two days you can try warm compresses. They increase blood circulation in the lower back and relieve pain by interrupting pain signals from nerve endings to the brain. It is best to use an electric heating pad for this. If you don't have it, a regular one will do. You can also simply take a warm bath.

Surgery

Surgical methods for the treatment of radicular syndrome in the lumbosacral spine are necessary in cases where there is resistance to conservative treatment or there are symptoms indicating severe compression of the root such as:

• Increased radicular pain
• Signs of increased root irritation
• Muscle weakness and atrophy
• Incontinence or bowel and bladder dysfunction

As symptoms worsen, surgery may be indicated to relieve compression and remove degenerative tissue that is affecting the root. Surgical treatments for radicular syndrome in the lumbosacral spine will depend on which structure is causing the compression. Typically, these treatments involve some way to decompress the spine or stabilize the spine.

Some surgical procedures used to treat lumbar radiculopathy are:

• Fixation of vertebrae (spinal fusion - anterior and posterior)
• Lumbar laminectomy
• Lumbar microdiscectomy
• Laminotomy
• Transforaminal lumbar
  intercorporeal fusion
• Cage implantation
• Correction of deformity

Ways to prevent lower back pain

To prevent lower back pain, you must:

• Provide yourself with adequate exercise - do exercises in the morning, simple exercises to stretch the muscles and spine.
• Periodically take massage courses - classic, cupping on trigger points.
• Do warm-ups or undergo cryotherapy courses as prescribed by your doctor.
• Eat right to avoid gastrointestinal pathologies. It is necessary to maintain a balance of proteins, fats, carbohydrates, and consume enough plant fiber. Alcohol, fatty, fried, salty and spicy foods should be excluded from the diet. Do not overuse smoked and canned foods, fast food. Another important point is the drinking regime: you need to drink 1.5-2 liters of liquid per day (along with soups, tea, etc.).
• At the first signs of illness, you should consult a doctor. In the early stages, almost any disease can be cured quickly and easily, without any consequences. If you are predisposed to lower back problems, you should visit a neurologist for prevention at least once a year.

Our clinic address: St. Petersburg, st. Bolshaya Raznochinnaya, 27 metro station Chkalovskaya

Forecast

In most cases, it is possible to treat radicular syndrome in the lumbosacral spine conservatively (without surgical intervention) and restore ability to work. The duration of treatment may vary from 4 to 12 weeks depending on the severity of symptoms. Patients should continue to perform exercises at home to improve their posture, stretching, strengthening, and stabilization. These exercises are necessary to treat the condition causing radicular syndrome.

Prevention

The development of radicular syndrome in the lumbosacral spine can be prevented. To reduce the likelihood of developing this condition you should:

• Practice good posture while sitting and standing, including while driving.
• Use proper body mechanics when lifting, pushing, pulling, or performing any activity that places additional stress on the spine.
• Maintain a healthy weight. This will reduce the load on the spine.
• No smoking.
• Discuss your profession with a physical therapy doctor, who can analyze work movements and suggest measures to reduce the risk of injury.
• Muscles should be strong and elastic. It is necessary to consistently maintain a sufficient level of physical activity.