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Leg Pain

Runners with leg pain often suffer from one of three entities: anterior knee pain, shin pain, or Achilles tendon and heel pain. These can be the cumulative result of increases in midseason training that overtax young athletes. In general, the intensity, duration, and frequency of training should not be increased by more than 10% in a given week. So, a runner who runs 20 miles a week should run no more than 22 miles the next week at the same pace without adding hills or sprint work. Table 1 lists specific age-based recommendations for maximum running distances.

TABLE 1
Recommended maximum running distances per day
Age (yr)
Distance (km)
<9
3
9-11
5
12-14
10
15-16
21.1 (half-marathon)
7
30
18
42.2 (marathon)

Multiple minor injuries or repeated injuries to the same area are signs of inadequate rest and rehabilitation. The highest risk factor for subsequent injury is incomplete rehabilitation of a primary injury. Athletes with first-time injuries should therefore diligently rehabilitate before returning to play. Special attention must be paid to a history of stress fractures anywhere in the body. In a female athlete, such a history may be the only obvious sign of the female athlete triad of osteoporosis, menstrual irregularities, and an eating disorder. Although no athlete is immune from the consequences of inadequate nutrition, a young woman who participates in an endurance activity or "appearance" sport such as figure skating and gymnastics is at particular risk.

Substantial physical activity coupled with inadequate caloric and protein intake can lead to primary amenorrhea (no sexual development by 14 years of age or no menarche by 16 years) or secondary amenorrhea (three or more months between periods or fewer than six periods in 12 months). Such "athletic" amenorrhea is a diagnosis of exclusion made only after complete evaluation and exclusion of other causes. The consequences of amenorrhea include decreased circulating estrogen levels, leading to osteopenia or osteoporosis with an increased risk of stress fracture. Active youth, particularly adolescents undergoing a growth spurt, often have astounding caloric needs-as many as 4,500 kcal/d.17 Aside from optimal caloric intake, the most crucial nutritional issues surround adequate calcium, iron, protein, and fluid intake (Table 2)

TABLE 2
Guidelines for intake of fluids and essential nutrients


Fluids

 Before exercise: 16 oz
15-30 min before starting
During exercise: 4-8 oz
every 15 min
After exercise: 16 oz for every pound of body weight lost


Calcium

 1,200 mg/d for ages
11-24 yr (US RDA)
1,500 mg/d for amenorrheic women (NIH recommendation)


Iron

 15 mg/d


Protein

 1.2-1.4 g/kg/d
(endurance sports)
1.2-1.7 g/kg/d
(strength sports)

Anterior knee pain
In immature athletes, frequent knee extension can lead to traction apophyseal injury with local tenderness at secondary growth centers of the distal patellar pole (Sinding-Larsen-Johansson disease) and the tibial tubercle (Osgood-Schlatter disease). Post activity ice massage to these painful areas can be of great benefit. Patellofemoral pain syndrome (PPS) can affect an athlete of any age. It is characterized by complaints of vague pain around or underneath the patella that worsens with prolonged running, standing, or sitting in a chair. Swelling and frank instability are uncommon, though the patient may feel that the knee "collapses" due to the anterior knee pain. The exact mechanism of PPS is uncertain, but many believe that malalignment of the patella about the distal femur is the main problem. Weak or uncoordinated quadriceps muscles, especially the vastus medialis oblique (VMO), can lead to abnormal lateral movement of the kneecap or excessive contact of the patellar undersurface with the femur, both leading to pain.

Tight hamstrings can be a root cause of anterior knee pain by placing greater resistance on the extensor mechanism. Increasing hamstring flexibility is the cornerstone of rehabilitation. VMO strengthening can help in some cases. Correction of hyperpronation (see the discussion under shin pain that follows) can also help alleviate symptoms. Ice and NSAIDs can be used to reduce inflammation and discomfort.

Shin pain
Repetitive eccentric contractions of the foot dorsiflexors during heel strike in running can lead to medial tibial stress syndrome (so-called shin splints), an inflammatory condition of the tibialis posterior and soleus muscle aponeurosis-periosteal interface at the medial border of the tibia. With this syndrome, there is no numbness or tingling in the lower leg or foot. Further along the continuum are tibial stress fractures, most frequently found on the medial border of the distal tibia. Whereas shin splint pain is usually diffuse and occurs on the medial border of the tibia and the surrounding soft tissue, pain from a tibial stress fracture tends to be focal (the athlete can often identify the painful area with the tip of a finger) and localized more toward the tibial spine than toward the surrounding soft tissue.

Another differentiating factor is that activity actually reduces the discomfort of shin splints, while repeated impact activity intensifies the pain of a tibial stress fracture.

Most cases of shin splints and tibial stress fractures are non-emergent; the exceptions are patients who have focal pain localized to the proximal tibial spine. Because stress fractures of the anterior tibial cortex are more likely than other fractures to become complete fractures, patients with such focal pain should be placed on non-weight-bearing status and immediately referred for orthopedic consultation.

Although plain radiographs have sub optimal sensitivity for stress fractures, they remain the method of choice for initial investigation. Standard views include anterior-posterior, lateral, and bilateral oblique views of the tibia and fibula. Periosteal elevation and cortical irregularities are common "soft" findings in suspected stress fractures. Triple-phase bone scans have greater sensitivity and specificity for both medial tibial stress syndrome and stress fractures, and are often part of specialty consultation. Treatment includes limiting impact activities such as running and jumping and using medial arch supports to correct hyperpronation. Nonimpact endurance activities such as biking, swimming, or pool-running (in which the person wears a floatation vest that allows a running motion while "floating" in the pool) are excellent alternatives during the healing phase. Ice massage on the painful regions can help ease the discomfort of shin splints.

Achilles tendon and heel pain
The Achilles tendon has been termed "the thermometer of the runner"-when a light squeeze produces pain, the runner has almost certainly been overtraining. Achilles tendinosis is caused by chronic overload of the gastrocnemius and soleus muscles during push-off, resulting in degenerative changes within the collagen substance of the tendon. This condition is usually seen in more mature adolescent and adult athletes. Athletes between 8 and 12 years are more apt to have Sever disease, focal tenderness and inflammation of the Achilles tendon insertion (rather than the tendon itself) into the apophyseal region of the calcaneus.

Radiographic examination is usually not indicated. The recovery period can be prolonged, with treatment focused on stretching of the Achilles and the initial use of heel cups or wedges to reduce the impact on the Achilles-calcaneus insertion. Ice massage to the body or calcaneal insertion of the Achilles tendon can be beneficial, and NSAIDs can reduce pain and swelling.

January 2002