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The influence of plyometrics training on the maximal power of the lower limbs in basketball players aged 16–18
Table 1. Material
Group Category
experiment lasted from January 30 2006 to June 2
2006, and it was divided into preparation – introduction
phase (8 weeks) and experiment proper phase
(I and II, 8 weeks). The aim of the preparation phase,
during which the subjects trained twice a week (using
their own bodyweight, mats, and exercises with
a partner) was to develop athletic prowess and practice
the correct take-off technique in jump exercises.
The experiment proper I (4 weeks) aimed at building
explosive leg strength through the application of selected
plyometric exercises. In the experiment proper II
(4 weeks) training loads were increased on the basis of
individual abilities of the players. To achieve that, basketballs
as well as 1 kg and 4 kg medicine balls were
used in plyometric training. The number of jumps was
also increased, but the structure of particular training
units did not change. The microcycle structure details
in the experiment proper phase I and II are presented
in Table 2.
Motor ability level was assessed prior to (on 25
March 2006) and after the experiment completion (on
24 June 2006), with the following research tools:
1. Laser diode system LDM 300C-Sport, used to assess:
– running speed at 5m, 15m, 20m and 30m
– speed endurance in 10 × 30m run.
2. KISTLER dynamometer platform with MVJ [23]
software, used to assess:
– explosive leg and trunk strength measured by
vertical jump with no arm swing.
3. EN-Knee isokinetic dynamometer (Enraf Nonius,
Holland) used to estimate the values of:
– dynamic strength of knee fl exors and extensors
at 60º/s angular velocity (5 repetitions) and
120º/s angular velocity (10 repetitions) as well
as the conventional muscle torque ratio of knee
fl exors and extensors,
– strength endurance of knee fl exors and extensors
at 240º/s angular velocity (15 repetitions)
as well as the conventional muscle torque ratio
of knee fl exors and extensors.
Number
of players
– 35 –
Age [years] Training
advancement
x ± S min – max [years]
Experimental (E) Juniors 18 16,8 ± 1,2 15,3 – 18,3 6,2
Control (K) Juniors 18 15,8 ± 0,8 14,5 – 16,4 4,7
The dynamometer had been used in previous research
[24], and the evaluation of the muscle dynamic
potential in isokinetic conditions (including warm-up,
stabilization, rest period) was performed according to
methodology described by Grygorowicz [25].
Descriptive statistics was used in data analysis. It
was found out that the empirical data distribution was
close to normal, which allowed for the analysis of variance
(ANOVA) with repeated measures. Since the
condition of data globosity was not fulfi lled, the multifactor
analysis was used. To assess the signifi cance
between respective test differences post hoc Tukeys’
test was done. To compare related pairs from test I and
II, the Wilcoxon Matched-Pairs Ranks test was used.
Statistical signifi cance was set at p < 0.05. Statistica 5.0
software was used for statistical analysis.
Results and discussion
The study confi rmed the effectiveness of the specifi c
plyometric training. Subjects from the experimental
group obtained signifi cant improvement in the majority
of analyzed variables. In the control group, comparing
the results before and after the experiment, differences
appeared in motor abilities levels; however, they were
not statistically signifi cant (p > 0.05) (Table 3–12, Fig.
1, 2).
Elevating the center of body mass during a vertical
jump on spot with no arm swing may be the basis
for an estimate of leg and trunk strength-speed ability
level in basketball players [26]. The obtained data did
not show any signifi cant difference in explosive leg and
trunk strength measured on a dynamometer platform
(Table 3).
The analysis of strength abilities test results performed
before and after the experiment in isokinetic
conditions showed an improvement of strength level
in the experiment group, and in the majority of players
the difference was statistically signifi cant (Table 4–8).
The most noticeable is the signifi cant difference in the
level of knee fl exor strength at all tested angular veloci-