As an undergraduate in Sport Technology BSc (Hons) at Sheffield Hallam University, Shirley Acquah-Davis has a strong interest in human locomotion. Her desire to gain experience working with biomechanical technologies led Shirley to a placement with Target3D where she led a project investigating the effect of fatigue on the biomechanics of three-point shooting within basketball players.
Shirley explains the mocap technology she used and shares highlights of her results... My aim was to investigate the effect of fatigue on the biomechanics of three-point shooting within basketball players. I considered a branch of biomechanics called kinematics; these variables describe motion. Using the OptiTrack motion capture system I could use the tracking data captured to calculate kinematic joint angle data during the post data analysis process. Also, I considered surface electromyography (EMG), which enabled me to collect data on muscle function, and how it behaves within a fatigued state.
Firstly, I captured three basketball players performing free-throw and three-point shots. Although this didn’t entirely go to plan, I learnt a lot about how the motion capture system would function within a Basketball court environment as with the shiny floor and lighting it’s not a traditional motion capture space. I used this experience to help design and conduct a case study around a professional basketball player. I tracked his upper body kinematics using the OptiTrack motion capture system and Delsys helped me out with providing the EMG equipment, the Trigno Avanti Sensors. Integrating the Trigno Avanti sensor system with Motive 3.0 software allowed me to synchronise the EMG and motion capture data. Initially, this was very challenging as I had to get my head around the technical info about how the two systems work separately before figuring out how the different systems could run together during performance.
As I had practiced the integration countless times, the data collection ran smoothly and I was able to capture good data from the player to export into Visual3D, a biomechanical software for post data analysis. Researcher Dr José Luis Parreño Catalán provided assistance by generating graphs and reports within Visual3D.
Key highlights from the results were that fatigue did not largely affect the player's kinematics during three-point shooting. Between conditions, their joint angles were very similar, and similar results were reported by some other scientific studies too. So, consistency is a good thing! This means that even when tired, the player can remain consistent with the kinetic chain principle, generating their kinetic energy from their lower body and allowing this to translate efficiently through a strong upper-body technique. This could be attributed to the high-performance level of the player, as they have excellent shooting fundamentals and are also well-conditioned. The kinematic data, captured by the mocap system, highlights this consistency as there was no significant angle variation between conditions.
The EMG data also supported this, as the player had higher muscular activation of the flexor carpi radialis muscle towards the end of the shot, during flexion of the wrist in the fatigued state. This suggests that even though their shooting motion technique was similar between conditions, towards the end of the shot by engaging their forearm muscles more, they held a stronger follow-through. Indicating that they perhaps focused on optimising their shooting form when tired by holding their follow-through to maximise the potential of their shot.
Although I created this project to learn about the application of the technologies and the integration between the two system, the results have made me curious about investigating shooting mechanics using motion capture within a basketball game-like environment, using multiple people - maybe using markerless motion capture. My longer term aim is to become a Biomechanical Researcher working with biomechanical technologies to measure and evaluate human movement.
Shirley’s research took place at Target3D’s motion capture studios in Hoxton and Guildford.