Jump-roping had a significant positive impact on the length of jumps compared to the common protocols. The
difference between the peak of power or the height of jumps was not significant. This study also illustrated that
common protocol and jump-roping improve the peak of power and the height of jumping.
Makaruk in 2013 implies that warm-up exercises, involving jump-roping, have greater impact on the length of
jumps compared to the common jumping protocols, and the common jumping protocol and jump-roping provide
same increase in vertical jumps (12).
When power enhances, strength should also increase. Jump-rope exercises may cause muscle protein degradation, as
a result of increased strikes and resistance. However, this process also causes a potential of increase of muscle sizes
and power. With the increase of power, when speed stays still, the strength also improves.
It should be noted that, jump-roping is a jumping exercise and it is highly similar to the Plyometric Exercises.
Similar to the Plyometric exercises, jump-roping also have two levels of extrovert contraction and rapid introvert
contraction. During the extrovert contraction, when the Quadriceps and twin muscles are stretched, the elastic
components are also stretched. Thus, part of the energy is stored in the form of elastic potential energy. During the
introvert contraction, this energy releases and results in the increase of power and the speed of movement. An
increase in the mentioned factors also causes the improvement of strength. Additionally, the nervous coordination
that occurs as a result of power exercises, such as Plyometric and jump-roping (the stretching reflex of muscle
spindles), results in the increase of power (22).
Generally, it can be concluded that, an improvement of muscle strength, jumping performance, and running at high
speed, are linked with two qualities of the muscles. First, strong muscular tension prior to the contraction which
results in tensile reaction to activate the introvert muscle contraction.
The reactionary nature of the muscle fibers, saves energy during activities. Determining the effect of these factors is
a difficult task (23). Improvement in tests, can occur as a result of increased excitability and neuromuscular
performance of the twitch motion components. These exercises stimulate muscle spindles and improve muscular
power.
In fact, power is used in jumps and throws. These exercises also improve power. Power is the most important factor
in the success of an athlete.
According to the findings of this study, 15 weeks of jump-roping did not results in a significant change in the speed
of 9 to 10 years old female students. Similar to this study, Portavi et al. in 2013 have found that 7 weeks of jump-
roping 15 to 50 minutes daily and three days per week, caused a non-significant change in speed up to %0.29. This
factor is measured by 50 meters running test after 7 weeks of jump-roping. The results are in line with what is
achieved in the current research.
There exist few researches related to the effect of jump-roping on speed (1). The percentage of muscle fibers (slow-
twitch and fast-twitch), determine the speed of an individual. While the percentage of muscle fibers are determined
during the first years of life or even prior to birth. The genes that are inherited from parents are determining the
percentage of muscle fibers. Therefore, speed seem to be a heritable trait. Although it may be increased by some
exercises, this change is not noticeable. This fact can be the result of a slight change in the speed of the students
after jump-rope training.