CHAPTER 88 • RUNNING 521
amount of extension actually decreases slightly.
Overall ROM was determined to be 43°with max-
imum flexion and extension—measuring 37 and
6 °, respectively, for normal walking. In running,
however, overall range of motion was increased to
46 °with the hip flexing and never quite returning
past neutral into extension (Birrer and Buzermanis,
2001; Oonpuu, 1994).
- The knee
- As in the hip, the most significant motion occurs in
the sagittal plan. The knee joint demonstrates
increased flexion as velocity increases, but exten-
sion is, as in the hip, decreased. Maximum flexion
in walking reaches 64°, and extension is − 8 °(8°of
flexion). In running, maximum flexion reaches
79 °, and extension is − 16 °(16°of flexion) (Birrer
and Buzermanis, 2001; Mann and Hagy, 1980).
- The ankle and foot
- Overall ROM at the ankle during walking is esti-
mated to be 30°, with maximum plantar flexion of
18 °and maximum dorsiflexion of 12°. Running
produces a greater overall ankle ROM of 50°due
to increased hip and knee flexion during running
(Birrer and Buzermanis, 2001).
2.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 plantar
flexion that it undergoes while walking, the
amount of supination in the subtalar joint is limited
but the degree of pronation is increased (Birrer and
Buzermanis, 2001).
- Subtalar motion is determined by muscular activity
as well as response to ground reactive forces.
Midtarsal joint motion, however, is determined by
subtalar position (Birrer and Buzermanis, 2001).
- When the calcaneus and the talus are supinated,
the axis is such that an increased obliquity is pro-
duced across the oblique and longitudinal mid-
tarsal 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, serv-
ing to unlock the midtarsal joint and allowing an
increased ROM for adaptation to the ground sur-
face as well as absorbing the ground reactive
forces, which lets the foot become a “mobile
adapter.” This occurs during the midstance (Birrer
and Buzermanis, 2001).
5. As the foot makes contact with the floor, the
pelvis, femur, and tibia begin the process of inter-
nal 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 unlock-
ing 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 (Birrer and Buzermanis, 2001).
KINETICS
•Walking produces vertical ground reactive forces
equal to 1.3 to 1.5 times body weight (Jacobs and
Berson, 1986). During running, these ground reactive
forces equal three to four times that of normal body
weight (Rodgers, 1988).
- The percentage of muscle activity increases through-
out 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 to 80% of the stance phase (Mann).
- During walking, the gluteus maximusis 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, how-
ever, it is active from terminal swing through 40% the
stance phase. This helps to produce hip extension
(Birrer and Buzermanis, 2001).
- The hip abductorsfunction during the terminal swing
and throughout 50% of the stance phase during walk-
ing and running. This serves to stabilize the stance leg
pelvis at IC, which prevents excessive sagging of the
swing leg (Birrer and Buzermanis, 2001; Inman,
1947).
- The hip adductorsare active during the last one-third
of the stance phase during walking. During running,
they are active during the entire stance and swing
phases (Birrer and Buzermanis, 2001; Mann).
- The quadricepsare 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 con-
tact, 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 to 60% of
the running stance phase and for only 25% of the
walking stance phase (Birrer and Buzermanis, 2001).
