The athletic performance level is one of the main factors that determine the success of an athlete. However, the athletic performance level of an athlete is determined by many motor abilities. One of these motor abilities is agility.~Because agility has been seen as a complex physical skill, valid and reliable tests and test devices are needed to determine the level of agility. Therefore, researchers have developed many test devices using technology and they have aimed to reach gold standards to measure agility ability through these devices. In this context, manual timers were first used to measure agility performance, then devices such as fully automatic test devices, photocell types, video timers, and radar systems were accepted as a test tool for the measurement of agility performance. Although fully automatic test devices are accepted as the gold standard in the measurement of velocity-based parameters, they cannot be preferred by everyone due to obstacles such as the need for expert knowledge and being economically costly for their use.~Due to the impracticality of accessing the gold standard test devices, researchers have developed easy-to-use and cost-effective smartphone applications that do not require expert knowledge, and these applications have been used to measure different motor abilities. Among these motor features, CODTimer App is the smartphone application that is frequently preferred in the evaluation of agility ability and whose validity-reliability studies are conducted.~In the previous studies on the validity and reliability of the CODTimer App, a very strong correlation was found between the CODTimer App and the gold standard automatic timing gates according to the 5+5 and 505 agility test protocols. However, many mobile applications have validity and reliability unexplored. It is necessary to investigate different test protocols and devices to spread the use of mobile applications and prove that they are valid and reliable measurement tools.~This study aimed to determine the validity, reliability, and usefulness of the CODTimer, Second Count, and Stopwatch Moviewatch App with an iPhone 11 compared to gold standard timing gates for the evaluation of Illinois agility performance in college athletes.
Due to the impracticality of accessing the gold standard test devices, researchers have developed easy-to-use and cost-effective smartphone applications that do not require expert knowledge, and these applications have been used to measure different motor abilities. Smartphone applications such as CODtimer, Stopwatch Movie watch, and Seconds Count are used to evaluate the ability to change direction within these biomotor features. However, the validity and reliability of these applications are the subjects of research.