Purpose: Sprinting, bouncing, and spontaneous landings are associated with
a forefoot contact whereas walking, running, and jumping are associated wit
h heel-toe foot placement. Because such foot placement strategies influence
landing mechanics or the ensuing performance, the purpose of this work was
to compare lower extremity kinematics and kinetics and muscle activation p
atterns between drop vertical jumps performed with heel-toe (HTL) and foref
oot (FFL) landings, Methods: Ten healthy male university students performed
two types of drop jump from a 0.4-m high box placed 1.0-m from the center
of the force plate. They were instructed to either land first on the ball o
f the feet without the heels touching the ground during the subsequent vert
ical jump, i.e., forefoot landing jump (En), or to land on the heels follow
ed by depression of the metatarsals, i.e., heel-toe landing jump (HTL). Thr
ee successfully performed trials per jump type were included in the analysi
s. The criteria for selection of the correct jumps was proper foot position
at contact as judged from video records and the shape of force-time curve.
Results: The first peak and second peak determined from the vertical force
-time curves were 3.4 times greater and 1.4 times lower for HTL compared wi
th those with FFL (P < 0.05). In the flexion phase of HTL, the hip and knee
joints contributed 40% and 45% to the total torque, whereas during Fn the
greatest torque contributions were 37% for both the knee and ankle joints.
During the extension phase, the greatest torque contributions to the total
torque were 41% and 45% by the knee and ankle joints during HTL and 34% and
55% during FFL. During the flexion phase, power production was 20% greater
(P < 0.05) in HTL than in Fn, whereas during the extension phase power pro
duction was 40% greater in FFL than in HTL. In the flexion phase of HTL the
hip and knee joints produced the greatest power, and during the extension
phase the knee and ankle joints produced the greatest power. In contrast, d
uring both the flexion and extension phases of Fn, the knee and ankle joint
s produced the greatest power. The EMG activity of gluteus, vastus laterali
s, and plantar flexor muscles was similar between HTL and FFL in most cases
except For the greater vastus lateralis EMG activity during precontact pha
se in HTL than in FFL and the greater gastrocnemius activity in Fn than in
HTL. Conclusion: Foot placement strategy modifies the individual joint cont
ributions to the total power during drop jumping.