Investigation of Vision on Knee Joint Velocity Sense in Healthy Adults

The study included two tasks to test how well people could reproduce the speed of knee movement at two different speeds (20°/s and 120°/s) under two vision conditions: eyes closed and eyes open. It included 10 participants. The equipment used was a Biodex 4 Pro dynamometer, an eye mask, and a goniometer. Participants wore shorts so that the knee area was free for the measurements. Before starting, each participant's height, weight, age, and sex were recorded. All measurements were done while sitting. The order of the tests was random. Each participant chose the first four letters of the alphabet at random, and each letter matched a combination of speed and vision condition (A: eyes closed, B: eyes open, C: 120°/s, D: 20°/s). For the eyes-closed condition, participants wore the eye mask. The tests were conducted in a quiet room to help participants focus. First, the knee was moved passively by the machine so participants could feel the speed. Then, they tried to reproduce the same speed themselves. The 20°/s tests had 5 repetitions, and the 120°/s tests had 8 repetitions. The whole session lasted about 20 minutes. Participants tried to stay focused, and at the end of each condition, they rated their attention using a simple 10-point scale.