|
|
|
|
JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
|
 |
|
Research
article
|
EFFECTS OF WARM-UP ON VERTICAL JUMP PERFORMANCE AND MUSCLE ELECTRICAL ACTIVITY USING HALF-SQUATS AT LOW AND MODERATE INTENSITY |
|||||||||
Konstantinos Sotiropoulos1, Ilias Smilios1, Marios Christou1,2, Karolina Barzouka3, Angelos Spaias1, Helen Douda1 and Savvas P. Tokmakidis1  |
|||||||||
1Department of Physical Education and Sport Science, Democritus University of Thrace, Komotini, Greece 2Department of Life & Health Sciences, University of Nicosia, Cyprus 3Department of Physical Education and Sport Science, National and Kapodistrian University of Athens, Greece |
|||||||||
|
|||||||||
© Journal of Sports Science and Medicine (2010) 9, 326 - 331 |
|||||||||
|
|
| ABSTRACT | |||
| The purpose of this study was to determine the effects of a specific
warm-up using half-squats at low and moderate intensity on vertical jump
performance and electromyographic activity of the thigh muscles. The subjects
were 26 men who were divided into a low intensity group (LIG; n = 13) and
a moderate intensity group (MIG; n = 13). The LIG performed a specific warm-up
protocol that included the explosive execution of half-squats with loads
25 and 35% of the one repetition maximum (1RM) and the MIG with loads 45
and 65% of the 1RM. The two groups performed a countermovement jump (CMJ)
before and three minutes after the specific warm-up protocols. During the
concentric phase of the CMJ a linear encoder connected to an A/D converter
interfaced to a PC with a software for data acquisition and analysis allowed
the calculation of average mechanical power. The electromyographic (EMG)
activity of the vastus lateralis (VL), vastus medialis (VM) and rectus femoris
(RF) were recorded during the concentric phase of the jumps. The average
quadriceps (Qc) activity (mean value of the VL, VM and RF) was also calculated.
A two way ANOVA (protocols X time) with repeated measures on the second
factor was used to analyze the data. Following the specific warm-up procedure
both groups improved (p < 0.05) CMJ performance and mechanical power
by 3.5% and 6.3%, respectively, with no differences observed between the
two groups. EMG activity of the Qc and VL increased (p < 0.05) for both
groups by 5.9% and 8.5%, respectively. It is concluded that the use of a
specific warm-up that includes half-squats, performed explosively with low
to moderate intensity, improves CMJ performance. This may be due to increased
muscle activation as evaluated by the surface EMG.
Key words: EMG, contrast training, resistance exercise. |
|