Health for recreational runners
The number of recreational runners in the United States is estimated to be 30 million. Recent growth in the popularity of this sport has resulted in increased associated injuries to the lower extremity. According to some reports, approximately 60 percent of these enthusiasts will eventually experience an injury that may limit their activities. Common injuries to runners and joggers include shin splints, patellofemoral pain syndromes, Achilles tendinitis, plantar fasciitis, compartmental syndromes, and stress fractures.
All of these conditions start as stress reactions to soft tissues and/or bone. Running places tremendous stress on the lower extremities, as up to 250 or 300 percent of the runnet's body weight may need to be absorbed by the musculoskeletal system at heel strike. That can be the equivalent of absorbing 375 - 450 lbs. per heel strike for a 150-lb. runner. In the course of one mile, the feet must endure this process between 1,200 and 1,600 times. Overuse injuries often result.
Any underlying structural deficit of the lower extremity may magnify the effects of overuse. Hyperpronation, excessive supination, and leg length inequality (with its associated pelvic unleveling) are common intrinsic findings in the general population, and athletes are no exception. These conditions should be identified, addressed, and corrected during the pre-competition exams, or on an athlete's first visit to the doctor.
It is not unusual for the doctor of chiropractic, especially the sports-minded practitioner, to be consulted for the vague pain and non-specific symptoms accompanying the gradual onset of a stress reaction to the soft tissues and/or bone. These conditions can be effectively managed if identification is early and an appropriate treatment program is followed.
Stress reactions develop as a micrtrauma condition. There is no single traumatic causative event that the patient can recall since these problems develop insidiously over time, secondary to repetition. The source of these overuse syndromes is biomechanical stress that exceeds the body's inherent capacity to repair and adapt.
The repair process cannot keep up with the stressor and is overcome, with the eventual result that the tissue (ligaments, muscles, cartilage, disk, and bone) fails. Overuse injuries can be very disabling to an athlete, recreational or competitive-who is then unable to continue with his or her usual activities and the demands of sports.
Sources of Stress Reactions
The three major sources of microtrauma that may result in a stress reaction are:
Overuse-when a specific area in the body is exposed to an excessive amount of repetitive trauma, such as starting a new running program or workout regimen. Poor training technique -such as downhill or uphill running; or running on one side of the road or a banked track only, where the angulation of the road increases the weight-bearing stress and shear forces to one side of the lower extremity more than to the other. Inherent imbalances- excessive pronation or excess supination will result in poor shock absorption capacity. Where excessive pronation will predispose the run ner to stress reactions and fracture of the metatarsals, excessive supination will predispose the athlete to stress reactions and fractures of tibia and femur. Ninety-five percent of all stress fractures occur in the lower extremities, and 69 percent will be associated with running or jogging. Typically, the patient will present with a dull, aching pain that is difficult to localize. A history of a recently begun program, an increase of running, or a change in the running surface or distance may be revealed. It is important to remember that runners who have inherent structural deficits are more susceptible to stress reactions and subsequent fracture. Therefore, only a mild increase or change in activity may initiate a stress reaction. The pain will increase during the causative activity and then subside with rest, especially when weight bearing is limited.
Cinical Evaluation
Clinical evaluation of stress reactions is challenging since objective findings are usually not evident. Deep palpation that discovers pinpoint tenderness directly over the bone may reveal a stress reaction worthy of following up with more advanced diagnostic imaging. Traditional radiographs are not very sensitive to early osseous changes. Computerized tomography (CT) is somewhat more accurate in localizing the involved area, but again is not very sensitive to early changes. Magnetic resonance imaging (MRI) is arguably the most useful imaging procedure in the evaluation of reactions to bone in the early stages when the bone is trying to repair itself from increases in biomechanical stresses. Triple-phase bone scans are also very sensitive to early stress responses; however, the "hot spot" is not specific. MRIs are not only sensitive, but also more specific to help rule out other skeletal conditions (tumors, infections, and other pathologies) and assist in grading the stress reaction.
It is relatively easy to adjust the extrinsic factors that may initiate stress reactions by improving and/or modifying training technique, schedule, and intensity. Early treatment usually will alleviate the symptoms in a relatively short time frame.
However, any stress reaction symptom should serve as an indicator of an underlying intrinsic cause. A common source of excessive biomechanical stress to ligaments, muscles, and bones of the lower extremity is malalignment or asymmetry. Since standing, walking, and running require the lower extremity and pelvis to be in a closed pack position, compression forces are increased if there is any structural deficit (developmental or acquired), no matter how slight.
Analysis of Specific Conditions
Three specific conditions have been studied that can be easily noted and corrected in the chiropractic office:
Excessive pronation: The rolling inward of the hindfoot and midfoot beyond the normal acceptable parameters during standing, walking, or running. May be due to either arch collapse (acquired) or poor arch development (developmental). In either case, excessive torsional (twisting/shearing) forces are transmitted from the overpronated foot into the leg with each step taken.
During the gait cycle of a normal healthy foot that functions within the above parameters, there should be a rolling inward of the foot/ankle complex, with internal rotation of the leg upon contact and a rolling outward with external rotation as the foot moves into midstance and toe off. Both are required to effectively dissipate heel strike shock at the subtalar joint and knee.
Prolonged internal rotation of the lower extremity transmits stress to the pelvic region. Inward rotation of the femur brings the greater trochanter forward and outward, stretching the piriformis muscle. Because the piriformis originates at the anterolateral aspect of the S2-4 segments, the sacrum may be pulled into its most common subluxation pattern -anterior and inferior. This hip rotation pattern is commonly associated with myofascial back pain.
Excessive supination is characterized by a high arch with an upside-down "V" (W) presentation. The pes cavus foot remains too rigid and inflexible during walking and standing. This also results in poor attenuation of heel-strike shock. The normal rolling in and out of the foot/ankle complex and bones of the lower extremity is inhibited by the overall lack of normal motion at the subtalar joint. The person with a high arched foot is susceptible to developing stress reactions and stress fractures in the sesamoids, calcaneus, tibia, femur, and pelvis.
In both excessive pronation and excessive supination, pelvic unleveling may develop. The presenting condition of leg-length inequality is usually revealed during the clinical examination, postural evaluation, or on standing on postural anteroposterior lumbosacral radiographs. It must be determined if the discrepancy is caused by an anatomical/structural short leg, or from a functional short leg secondary to a biomechanical deficit in the biostatic chain of the lower extremity and/or pelvis.
There are many orthopedic tests and tape measurements that can indicate a leg-length inequality; however, unless the patient's history or diagnostic examination confirms there is an anatomical short leg, it is reasonable to assume the short-leg syndrome is due to a functional cause. The most common underlying cause of a functional leg-length inequality is asymmetrical bilateral pronation. Asymmetrical bilateral supination can also cause the serial distortion that results in pelvic unleveling; however, it is less common than excessive pronation.
Realizing the effect of the "Rule of Three" ("a limb-- length discrepancy is, during running, comparable in effect to ... [three times the] actual deformity at rest ... land] the increased strain is transmitted to the low back."), the well-disciplined doctor of chiropractic must closely scrutinize the postural status of the patient. A small, insignificant imbalance in a regular patient can amount to a large, significant imbalance in the athletic patient. And while an athletic patient may "look OK" in the office, this patient may be subjected to significant postural stress during the performance of his or her sport.
Orthotics
In-shoe orthotics have been called "the only method of controlling over-pronation at the subtalar joint."6 Ultralightweight, flexible orthotics can play a major role in preventing many over-use injuries in runners and joggers. Blake and Denton performed a retrospective study of 180 patients (primarily runners) receiving functional foot orthoses. The diagnoses included foot/ankle, knee, leg, and hip conditions. The success rate (a response of "definitely helped") was 70 percent. D'Amico and Rubin found a highly significant reduction of the Q-angle when orthotics were used. The mean Q-angle was reduced from 17.6 to 11.6 degrees. Both excessive pronation and supination will need an effective shock-absorption material built into the orthotic to help dissipate shock forces. Given that it is sometimes difficult to determine whether the runner is primarily a heel striker or a forefoot striker, it is recommended that the orthotics have pads in both the heel and forefoot areas for maximum shock protection. Depending on the degree of pronation and its effect on the forefoot, the orthotic may have a medial post or wedge built into the heel to help stabilize the calcaneus from rolling too far inward. Conversely, the highly supinated foot may need a lateral heel post to counter outward rolling of the heel. Creating a bilateral symmetrical foundation in the correct physiologic range for weight-bearing feet will aid in natural balancing and stabilization of the pelvis.
References
- Jacobe SJ, Berson BL. Injuried to runners: a study of entrants to a 10,000-meter race. Am J Sports Med 1986; 14:151-155.
- Lysholm J, Wiklander J Injuries in runners. Am J Sport., Med 1987; 15:168-171.
- Lutter LD. Foot-related knee problems in the long-distance runner Foot &Ankle 1980; 1:112-116.
- Robbin SF, Hanna AM. Running-related injury prevention through barefoot adaptations. Med Sci Sports Exerc 1987; 19.148-156.