The kinematics and kinetics of jumping for distance with particular reference to the long and triple jumps.
The common aim of the long and triple jumps is to attain maximum horizontal distance from
the front of the take-off board. This is achieved by converting some of the horizontal velocity
developed in the approach run into vertical velocity at take-off. The aim of this thesis was to
examine a theoretical model and to identify kinematic and kinetic factors that facilitate the
generation of vertical velocity in the long and triple jump take-offs.
A pivot mechanism was defined to act between touch-down and the instant the centre of mass
was directly above the toe of the support foot. This mechanism was found to be the largest
contributor to the gain in vertical velocity in all take-offs, accounting for 83.0% in the long
jump and 63.7%, 69.8% and 70.7% in the hop, step and jump take-offs. The contribution of
the pivot to the gain in vertical velocity at take-off in the long jump was significantly greater
than in each of the triple jump take-offs, (all P<0.002).
A relative momentum approach was used to determine the contribution of the free limbs to the
generation of vertical velocity. In the long jump, the free limbs made a 10.8% contribution to
the gain in vertical velocity, compared to 12.2%, 19.0% and 19.0% in the triple jump take-offs.
Multiple regressiona nalysesw ere used to identify factors relating to the generationo f vertical
velocity in the long jump (n=14).
The greatestg ains in vertical velocity were associatedw ith techniquest hat emphasiseda low
centre of mass and extended knee joint at touch-down and the ability to resist knee flexion in
the compression phase, R2=72.7%. The greatest losses in horizontal velocity were associated
with excessiveh ip adduction, less hip extensiona nd greater increasesin height from touchdown
to take-ofll R2=84.5%.
Ground reaction forces and net joint moments were measured during short approach running
jump tests. Peak vertical impact forces were greater in simulated `drop' take-offs, 5080 N,
compared to those experienced in `flat' approach take-offs, 3250 N, (P=O. 002). Peak
horizontal braking forces were 1800 N in both types of take-off. However, the peak net joint
moments about the ankle, (403 N. m and 387 N. m), knee (233 N. m and 296 N. m) and hip (292
N. m and 249 N. m) were similar between the `flat' and `drop' take-offs. This suggests that
athletes adapt their technique in the `drop' take-off to distribute the larger forces effectively
and to keep the net joint moments within controllable limits. Results indicated that strength
about the ankle joint was particularly important in both types of take-off, but depending on the
athlete's technique strength about the knee and hip are also vital. Greater flexion of the knee
joint at touch-down and maximum knee flexion were found to be associated with greater
average knee moments, R2=30.8% and 75.5% respectively, and greater angles of leg placement
were moderately associated with greater average hip moments, R2=23.5%.
In conclusion, this thesis has provided a greater insight into the kinetics and kinematics of
jumping for distance. It has quantified the contribution made by the pivot mechanism and the
free limbs to the generation of vertical velocity, and has assessetdh e demandso n the musculoskeletal
system in terms of ground reaction forces and net joint moments. The results indicate
that elite performers cannot rely on speed alone, and that strength and technique are major
factors of successful performance.