This research explores the general preparatory physical exercise program using Android for Volta Club tennis players and students of sport science faculty, Universitas Negeri Medan. This research adopts the method of the research and development model Borg and Gall. The development procedure used includes several stages: 1) recognizing the content of the product being developed, 2) developing the initial product, 3) expert validation. The data analysis technique used in this study was done in two ways, namely quantitative and qualitative. In this article, the data used is only at the validation stage of material experts and media experts. Based on the results of the material expert validation regarding the product, it can be obtained as follows: assessment of the material aspect obtained 86.70 % (Very Feasible), the aspect of human resources for sports personnel obtained 96% (Very Feasible), the mechanism for implementing the physical exercise program was 90% (Very Feasible), and the overall percentage was obtained 95.4% (Very Worthy). Next is the assessment of media experts from various aspects: Display 72.2% (Decent), Coloring 77.7% (Very Decent), Images (Photos/videos) 80% (Decent), Fonts 80% (Very Decent), Menu 80% (Decent), Ease 73.3% (Eligible), and the usefulness of the 96% aspect of the media expert's assessment stated that the android-based general preparation physical exercise program application media was very feasible. The overall percentage obtained is 79% with a decent category.

This study aims to develop a power sensor-based leg muscle test instrument where the instrument changes the concept from manual to digital and develops a manual for using the test tool. The products produced are the Power Limb Muscle Test Kit, and a manual for using the Power Limb Muscle Test Kit. This research was established by adjusting the research and development model of Borg & Gall. The development method used includes several stages: 1) investigating the contents of the product being developed, 2) elaborating the initial product, 3) expert validation, 4) field testing, 5) product modification. The sampling technique applied was purposive sampling with Phase I trials of 10 students of physical education, health and recreation, Sriwijaya University and Phase II trials of 20 students of sports education study program, Universitas Bina Darma. Additionally, from the Phase I trial, as many as 10 students of physical education, health and recreation showed 96% criteria of Very Eligible, subsequently from the Phase II trial, as many as 20 students of sports education study program showed 91% in the Very Eligible category. Based on these results it can be concluded that a power sensor-based leg muscle test tool can be used to measure leg muscles. The renewal of the results of this study is a measuring instrument that uses sensors as a medium for collecting data so that the results are more accurate, effective and efficient.