Objective: To determine the effect of strength training in inertial machines, on SJ CMJ and CMJ with arms; in youth volleyball players from the city of Cartago.

Methodology: A quasi-experimental study of quantitative order was carried out and takes up an empirical-analytical approach, quasi-experimental with pre-test - post-test evaluation. 32 female volleyball players, belonging to the minor category of the Fénix G Club of the city of Cartago Valle

Results: Both groups showed significant improvements in jump height, flight time, strength and power in the protocol that was carried out during the 12 weeks of intervention, but there was no statistically significant difference between the control groups (P = 0.356). , experimental (P = 0.984)

Conclusions:

Keywords: Inertial machines, Squat jump, Countermovent Jump, Abalakov

Objective: To determine the effect of strength training in inertial machines, on SJ CMJ and CMJ with arms; in youth volleyball players from the city of Cartago.

Methodology: A quasi-experimental study of quantitative order was carried out and takes up an empirical-analytical approach, quasi-experimental with pre-test - post-test evaluation. 32 female volleyball players, belonging to the minor category of the Fénix G Club of the city of Cartago Valle. The techniques that were used were: survey to determine previous injuries, adaptations that athletes may have against strength training and practice time in volleyball, observations were also developed to determine the levels of jumpability of each player, taking into account the Bosco's battery (3). For this we used:

• My jumps 2 application for IOS devices, it was used to determine the height of the CMJ, SJ, CMJ or ABK, this app was validated in 2015 by the creator, Dr. Carlos Balsalobre (15).
• Wheeler YOYO XS inertial machine contains an encoder validated by the company Chronjump (16) with this device the training program was carried out with the volleyball players, the program was subjected to expert judgment.

For the collection of information on sociodemographic variables, a data record was carried out (Weight, Height, History of injuries, etc.), in addition to this, a record per athlete for the values of each jump performed.

Results: Both groups showed significant improvements in jump height, flight time, strength and power in the protocol that was carried out during the 12 weeks of intervention, but there was no statistically significant difference between the control groups (P = 0.356). , experimental (P = 0.984)

Conclusions:

Keywords: Inertial machines, Squat jump, Countermovent Jump, Abalakov

Inclusion criterio

• That they express their participation voluntarily in the investigation by filling out their informed consent in the informed settlement.
• Sports aptitude in the execution of the tests at the time of the intervention and/or evaluation, do not present any surgical intervention in any particular area or region of the lower limbs.
• Practice time in volleyball of at least 2 years and 1 year in strength training

Exclusion Criteria:

• Presenting serious sports injuries 6 months before or during the data collection phase (pre-test and post-test) and application of training with inertial machines.
• not complete with at least 8 weeks of strength training on the inertial machine.

According to the availability of the subjects.

One of the main researchers evaluated the post-test without knowing who belonged to the control and experimental group, in addition to this, the other investigator was asked to evaluate the pre-test so as not to have biases or generate some type of modification in the results obtained by both groups.