The effects of plyometric and strengthening exercises on the quadriceps muscle strength in girl students in Zahedan University of Medical Sciences in 2005

Background: Varieties of exercise therapy methods are used in rehabilitation in order to
improve muscle function. Optimal function of muscles results in improvement of functional
activities; as a result, these activities would be achieved in a shorter time with the reduction of
energy wasting. The purpose of this study was to evaluate the effects of plyometric and
strengthening exercises on the quadriceps muscle strength in girl students of Zahedan University of
Medical Sciences.
Methods and Materials: This experimental study was performed in Zahedan in 2005. Thirty six
girl students aging 20 ± 1.2 years among residents of Mojtameh dormitory of Zahedan University of
Medical Sciences were studied through simple non-probability sampling. Subjects were randomly
assigned to either a plyometric exercises group or a strengthening exercises group. The quadriceps
muscle strength (kg) was measured using hand-held dynamometer before and after 10 sessions of
intervention. The first group received plyometric exercises. Strengthening exercises were given to
the second group. Independent and paired t-tests were used for comparison between the pretreatment
and post treatment results between groups and within groups, respectively.
Results: The strength of quadriceps muscle was increased from 12.1 ± 3 to 14.7 ± 3.8 (kg) in the
plyometric exercises group and from 12.4 ± 3.1 to 14.9 ± 3.9 (kg) in the strengthening exercises
group (P<0.0001). No significant difference was seen between two groups after and before
intervention. Independent-samples t-test identified that there was no significant difference between
two groups with respect to mean difference of the quadriceps strength.
Conclusions: The results, in spite of conventional opinions, showed that there was no difference
between plyometric and strengthening exercises regarding quadriceps muscle strengthening. Both
types of exercises increased the quadriceps muscle strength. Therefore, according to patient
conditions, either type of these exercises can be used for exercise therapy in knee pathologies and
the quadriceps muscle strength deficit.