Running
Robert Wilder
Francis G. O’Connor
EPIDEMIOLOGY OF RUNNING INJURIES (160)
There are over 30 million runners, of whom more than 10 million run on more than 100 days per year.
Injury rate ranges from 2.5 to 5.8 injuries per 1,000 hours of running (39,87,155). The lower rate of 2.5 per 1,000 hours is seen in long-distance and marathon runners. Sprinters have the highest rate of 5.8 injuries per 1,000 hours, and middle-distance runners are between the two at 5.6 injuries per 1,000 hours (87).
Common Injury Sites
Most running injuries are musculoskeletal overuse syndromes (Table 99.1); 70%-80% occur from the knee down.
Back: 5%
Hip and groin: 15%
Knee: 40%
Lower leg: 20%
Foot and ankle: 20%
Although there are no age- or gender-related differences, there are differences in injury pattern between sprinters, middle-distance runners, and long-distance runners. Hamstring strains and tendinitis are more commonly seen in sprinters; backache and hip problems are more commonly seen in middle-distance runners; and foot problems are more common among long-distance and marathon runners (87,121).
Risk Factors for Running Injuries (26,27,44, 72,88,146,154,159,160,165)
Important risk factors (for which a clear association with injury has been identified)
Training miles per week (risk increases at 19 miles per week and increases more sharply at 40 miles per week) (44,88)
Previous running injury (within past 12 months) (88)
Inexperienced runner (running < 3 years)
Recent transition in training
Training intensity
Cavus feet
Equivocal risk factors (for which evidence demonstrating a clear link with injury is unclear)
Hyperflexibility or hypoflexibility
Running shoes
Shoe orthotics
Roadside running
Malalignment problems (genu varum and valgus, high Q-angle, femoral neck anteversion, pelvic obliquity, knee and patella alignment, rearfoot valgus, leg length discrepancy)
Body morphology (slight protective effect in men with body mass index > 26 kg · m2)
Age
Unrelated risk factors (have not been associated with increase in running injuries)
Gender
Running surface
Cross-training
Time of day
Warm-up or cool-down periods
BIOMECHANICS OF RUNNING
The Running Gait Cycle
During walking, the stance phase occupies 40% of the gait cycle. The stance phase is decreased to approximately 30% while running and 20% while sprinting (18).
Walking differs from running in that walking has two double support periods in stance, whereas running has two periods of double float in swing. Running does not have a period of double support (18).
Kinematics
Generally, there is an increase in joint range of motion (ROM) as velocity increases. However, there are no major differences
between walking and running kinematics in the coronal and transverse planes. Most kinematic differences occur in the sagittal plane (18,112). The body lowers its center of gravity with increased speed by increasing flexion at the hips and knees and by increased dorsiflexion at the ankle (18,92).
Diagnosis
Percentage
Patellofemoral pain syndrome
32.2
Tibial stress syndrome, “shin splints”
17.3
Achilles tendinitis
7.2
Stress fractures
7.2
Patellar tendinitis
5.7
Iliotibial band syndrome
6.3
Metatarsal stress syndrome
3.3
Adductor strain
3
Hamstring strain
2.6
Posterior tibial tendinitis
2.6
Ankle sprain
2.4
Peroneus tendinitis
1.9
Iliac apophysitis
1.6
The hip
The hip demonstrates an overall increase in ROM as velocity increases. The most significant motion occurs in the sagittal plane. Most of this increase occurs in flexion, and the amount of extension actually decreases slightly. Overall ROM was determined to be 43 degrees with maximum flexion and extension, measuring 37 and 6 degrees, respectively, for normal walking. In running, however, overall ROM was increased to 46 degrees, with the hip flexing and never quite returning past neutral into extension (18,113).
The knee
As in the hip, the most significant motion occurs in the sagittal plane. The knee joint demonstrates increased flexion as velocity increases, but extension is, as in the hip, decreased. Maximum flexion in walking reaches 64 degrees, and extension is −8 degrees (8 degrees of flexion). In running, maximum flexion reaches 79 degrees, and extension is −16 degrees (16 degrees of flexion) (18,92).
The ankle and foot
Overall ROM at the ankle during walking is estimated to be 30 degrees, with maximum plantarflexion of 18 degrees and maximum dorsiflexion of 12 degrees. Running produces a greater overall ankle ROM of 50 degrees due to increased hip and knee flexion during running (18).
At initial contact, due to the increased hip and knee flexion, the ankle undergoes rapid dorsiflexion during the absorption phase. In running, because the ankle never quite reaches the amount of plantarflexion that it undergoes while walking, the amount of supination in the subtalar joint is limited, but the degree of pronation is increased (18).
Subtalar motion is determined by muscular activity as well as response to ground reactive forces. Midtarsal joint motion, however, is determined by subtalar position (18).
When the calcaneus and the talus are supinated, the axis is such that an increased obliquity is produced across the oblique and longitudinal midtarsal joints. This serves to lock the midtarsal joint functionally, thereby resulting in a decrease in available motion and allowing the foot to become a “rigid lever.” This occurs during late terminal stance and preswing. When the calcaneus and talus are pronated, the axis is such that an increased parallelism exists between the oblique and longitudinal midtarsal joints. This results in an increased available motion in these joints, serving to unlock the midtarsal joint and allowing an increased ROM for adaptation to the ground surface as well as absorbing the ground reactive forces, which lets the foot become a “mobile adapter.” This occurs during the midstance (18).
As the foot makes contact with the floor, the pelvis, femur, and tibia begin the process of internal rotation. This internal rotation lasts through loading response and into midstance, resulting in eversion and unlocking of the subtalar joint. This results in subtalar pronation, which allows unlocking of the oblique and longitudinal midtarsal joints, resulting in further pronation. The pelvis, femur, and tibia then begin to rotate externally, which causes inversion and locking of the subtalar joint (18).
Kinetics
Walking produces vertical ground reactive forces equal to 1.3-1.5 times body weight. During running, vertical ground reactive forces spike sharply at contact to produce an impact peak, may slightly decrease, and then continue to an active peak measuring 2.2-2.6 times body weight. It is thus during midstance when ground reactive forces are greatest, with peak internal joint moments generating peak mechanical stress on tissues (35,132).
It is unclear whether increased impact forces lead to injury or impact peak performance (35,62,63,105,108).
The percentage of muscle activity increases throughout stance phase during running. It is rare to see a muscle group active for more than 50% of the stance phase during walking, but in running, activity is noted for 70%-80% of the stance phase (91).
During walking, the gluteus maximus is active from the end of the swing phase until the foot is flat on the floor. This serves to decelerate the limb and stabilize the hip joint for initial contact. During running, however, it is active from terminal swing through 40% the stance phase. This helps to produce hip extension (18).
The hip abductors function during the terminal swing and throughout 50% of the stance phase during walking and running. This serves to stabilize the stance leg pelvis at initial contact, which prevents excessive sagging of the swing leg (18,67).
The hip adductors are active during the last one-third of the stance phase during walking. During running, they are active during the entire stance and swing phases (18,91).
The quadriceps are active at the end of the swing phase to bring about terminal knee extension and to aid in hip flexion, through a concentric contraction. They also help stabilize the knee joint at initial contact, through an eccentric contraction. In running, they are highly active during the absorption phase of stance to deal with the greater requirements of weight acceptance. They are continually active throughout knee flexion eccentrically to limit the rate at which knee flexion occurs. They are active for 50%-60% of the running stance phase and for only 25% of the walking stance phase (18).
During walking, the hamstrings are active at the end of swing phase and into stance phase until the foot is in full contact with the ground. This occurs in about 10% of the walking gait cycle. During running, they are active during the last third of the swing phase during hip and knee extension. Here they are acting concentrically across the hip joint but eccentrically across the knee joint. This action initiates hip extension and resists knee extension simultaneously (18).
During walking, the anterior tibial muscle group is active from late stance phase through the swing phase and then for the first 10%-15% of the next stance phase. This produces dorsiflexion of the ankle during the swing phase through concentric contraction. It also helps to control plantarflexion by initial contact through eccentric contraction, thereby preventing foot slap. During running, these muscles are active from late stance phase through the swing phase and for the first 50%-60% of the next stance phase. For their duration of activity, they are undergoing concentric contraction. During walking, they decelerate foot plantarflexion at initial contact; however, during running they appear to accelerate movement of the leg over the fixed foot. In heel strikers, a greater degree of activity is found in the anterior tibial muscle group than in midfoot strikers (18).
Activity of the posterior leg musculature begins during terminal swing of gait. During walking, these muscles act to resist forward movement of the tibia over the fixed foot during the stance phase. They are active from 25% to 50% of the stance phase through mostly eccentric contraction. During their last 25% of activity, they undergo concentric contraction to initiate active plantarflexion. During running gait, initial contact is a period of rapid dorsiflexion. Here the triceps undergo eccentric contraction, again to resist this motion. They are active for approximately 60% of the stance phase. Initially they serve to stabilize the ankle joint at initial contact, and then to provide for propulsion (18).
COMMON RUNNING INJURIES
Patellofemoral Syndrome (6,32,36,49,50)
Definition
Pain associated with the articular surface of the patella and femoral condyles
“Runner’s knee”; number 1 presenting complaint to runners’ clinics
Number 1 cause of lost time in basic training in military recruits
Anterior, peripatellar, subpatellar pain
Increased pain following prolonged sitting (theatre sign) as well as running downhill and walking downstairs
Apprehension (shrug) sign
Abnormal patella tilt (tilt < 5 degrees in males and < 10 degrees in females)
Abnormal patella glide (medial glide < two quadrants, lateral glide > three quadrants)
Femoral dysplasia
Patellar facet asymmetry
Malalignments contributing to excessive pronation
□ Femoral anteversion
□ External tibial torsion
□ Varus ankle, foot
Patella alta, baja
Increased Q-angle
Muscle and soft tissue imbalances
□ Weak vastus medialis oblique (VMO)
□ Tight lateral structures (iliotibial band [ITB], lateral retinaculum)
□ Weakness of hip abductors, extensors, external rotators
Correct biomechanical factors that lead to compensatory subtalar pronation and obligatory internal tibial rotation: genu valgum, tibia vara, hindfoot varus, forefoot pronation
Flexibility: ITB, hamstrings, quadriceps, gastrocnemius
Manual therapy to stretch tight retinaculum: medial glide and tilt
Strengthening: quadriceps with emphasis on VMO, hip abductors, extensors, external rotators
McConnell taping
Bracing (patellar straps and braces) (126)
With persistent symptoms, consider:
Iliotibial Band Syndrome (6,46,47,48,51,57)
Definition
An overuse tendinopathy of the ITB most commonly as it passes over the lateral femoral condyle.
ITB syndrome is the most common cause of lateral knee pain in runners, accounting for up to 12% of all running-related overuse injuries (10,23,85,106).
ITB syndrome results from repetitive friction of the ITB at the lateral femoral epicondyle. The ITB moves anterior to the epicondyle as the knee extends and posterior as the knee flexes, remaining tense in both positions (41,48,111). Specifically, the posterior edge of the ITB impinges against the lateral femoral epicondyle of the femur just after foot strike. This “impingement zone” occurs at or at slightly less than 30 degrees of knee flexion (111). Fairclough et al. (42) have alternatively proposed that ITB syndrome results from compression of the ITB against the lateral femoral epicondyle as a consequence of internal tibial rotation after foot strike as opposed to friction. Repetitive irritation can lead to chronic inflammation, especially beneath the posterior fibers of the ITB, which are thought to be tighter against the lateral femoral condyle than the anterior fibers (48,111).
The ITB is a continuation of the tendinous portion of the tensor fascia lata (TFL) muscle, with some contribution from the gluteal muscles. It is connected to the linea aspera via the intermuscular septum. Distally, the ITB spans out and inserts on the lateral border of the patella, the lateral retinaculum, and Gerdy’s tubercle of the tibia. The ITB is free from bony attachment between the superior aspect of the lateral femoral epicondyle and Gerdy’s tubercle (48,93,147).
Diagnosis
Lateral pain and crepitus at lateral femoral condyle (or insertion at Gerdy’s tubercle)
Tight ITB on Ober’s test
Abductor weakness
Varus positioning of knee, tibia, and foot
Increased hip adduction and internal rotation
Internal tibial torsion
Excessive supination or pronation
Abductor tightness and weakness
Higher knee flexion at heel strike
Downhill running
Running on crowned roads
Excessive running in same direction on trac k
Treatment
PRICEMM (protection, rest, ice, compression, elevation, modalities, medication); iontophoresis
ITB strap or dual-action strap
Foam roller exercise for soft tissue work
Myofascial release
Flexibility and strength (hip abductors, adductors, rotators, flexors, extensors)
With persistent symptoms, consider:
Injection (steroid)
MRI to rule out lateral meniscus, other
Shin Splints
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