| Summary: | It was the purpose of this investigation to evaluate continuous
concentric and eccentric isokinetic loading of the knee
extensors (KE) and flexors (KF) at 90, 135, and 180 deg/sec-1
in power athletes (PA), aerobically trained runners (ATR), and
a control group of moderately active individuals (MA). A total
of sixty healthy subjects (N= 20/group), aged 18-35 years, were
assigned to one of the three groups after physiological assessment
consisting of vertical jump and maximal oxygen consumption
(VO2 max) was performed. Gravity corrected concentric and
eccentric average isokinetic torque was measured from 75-30° of
knee flexion and knee flexion-extension ratios (KF-E ratios)
were calculated.
A three-way ANOVA with two repeated measures (angular
velocity and muscle group) was calculated for each measured
contraction type (concentric and eccentric). A third three-way
ANOVA with two repeated measures (angular velocity and contraction
type) was computed for the analysis of KF-E ratios . Significant findings were further analyzed using Scheffé's post
hoc comparisons. Finally correlations between the ability to
produce concentric and eccentric torque for the KE and KF and
VO2 max, vertical jumping ability , and skeletal muscle mass
(SMM) were examined using Person Product Moment Correlations.
It was found that the power group produced significantly
greater average concentric and eccentric isokinetic torque than
either the endurance (concentric and eccentric at p< 0.01) or
sedentary (concentric at p< 0.05 and eccentric at p< 0.01)
groups for both the KE and KF while the last two groups did not
significantly d i f f e r (p> 0.05). For all groups isokinetic
torque produced both eccentrically and concentrically by the KE
was significantly greater at p< 0.001 than that produced by the
KF at each angular velocity examined. As well, eccentric KF-E
ratios were significantly greater (p< 0.001) than those
produced concentrically for each of the three groups for a l l
angular velocities .
The power groups had significantly greater concentric and
eccentric KF-E ratios (p< 0.01) than either the endurance or
sedentary groups of subjects who did not d i f f e r significantly.
Concentric KF-E ratios significantly increased with increasing
angular velocities for both the endurance and sedentary groups
(p< 0.02) while eccentric ratios did not significantly change
with increasing angular velocity in any of the three groups of
subjects. Finally, there were significant correlations between
the ability to generate torque both concentrically and eccentrically by the knee extensors and knee flexors and vertical
jumping ability while VO2 max nor SMM significantly correlated
with vertical jumping ability .
These findings are important when designing individualized
conditioning and rehabilitation programs for athletes who are
training for activities which require different velocities of
muscular contraction. === Education, Faculty of === Curriculum and Pedagogy (EDCP), Department of === Graduate
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