Intrinsic foot muscle morphology and function in tennis players

The study will be conducted in the Susan Wakil Health Building Medical Imaging Suite Ultrasound Lab located on Level 3, Room 311. Only one participant will be present in the room at a time, with a single visit per participant needed. After reviewing the Participant Information Statement and consenting, the participant will complete a REDCap survey, which will consist of demographic questions such as age and years of tennis training. Validated self-report instruments, being the American Association of Orthopaedic Surgeons Foot and Ankle Questionnaire and Universal Tennis Rating Ranking Metric, will also be used to assess their injury status and tennis ability respectively. They will then have their weight, height, and full foot length measured. Static foot posture will be assessed with the Foot Posture Index to allow for comparisons of participant's feet accounting for body habitus. After this, the student researcher will then scan both the participant's feet using a Philips iU22 ultrasound machine with a linear array 5-12MHz transducer to take measurements of the selected intrinsic foot muscles abductor hallucis and flexor digitorum brevis. The scan protocol will be followed to ensure the accuracy and reliability of measurements. The student researcher will then guide the participant to the Archercise device, for a series of gentle exercises which will be explained, performed, and measurements recorded and saved. The Archercise measurement protocol will be followed to ensure the accuracy and reliability of measurements. The student researcher will be supervised by specialists in the area of ultrasound and foot muscle structure and function. No adherence monitoring is required for this study, as the observations required will be completed at a single point in time with no follow-up visits needed. All the data collected will be stored in a password-protected University Research Data Store. The study will take about 90 minutes to complete, as the unique time allocation is as follows: 1. Read through the participation information sheet and sign the consent form (approx.10min) 2. Complete the survey regarding demographics, tennis ability and any injury details (approx.20mins) 3. Have an ultrasound scan taken of both feet to assess the selected intrinsic foot muscles (approx. 30min) 4. Perform exercises on both feet to assess intrinsic foot muscle function on the Archercise biofeedback device (approx. 30 min) The ultrasound protocol is unique to the study and is as follows: The ultrasound machine will be set to a previously optimised “foot” pre-set for a consistent image setting across participants, with further optimisation of machine controls with regards to the participant's individual acoustic characteristics adjusted as necessary. The participant will be seated erect on an electric plinth, with the bed raised to a comfortable height for the operator. The knee and hip of the participant will be placed at 90 degrees flexion, with the participant's foot in a neutral position for the operator to scan. Bony landmarks will be palpated and marked with an erasable pen to ensure accurate, reproducible measurements are taken and to reduce measurement bias and operator dependence. This is to ensure the exact anatomical region is measured, as opposed to the widest or thickest aspect of the muscle. For the abductor hallucis muscle, the medial sesamoid bone and navicular tuberosity will be marked and palpated. The probe will be placed longitudinally to the medial sesamoid bone, and the muscle will be tracked to the navicular tuberosity. Here, the operator will ensure the probe is perpendicular to the participant's foot in contact with the region and turn the probe 90 degrees, where the participant will be asked to flex their 1st digit downwards against the operator's hand, with the movement reflected on real-time imaging, to ensure the correct muscle body is measured. Images will be taken in the transverse plane, and this process will be repeated three times, with average measurements taken for increased reliability. For the flexor digitorum brevis muscle, the probe is placed perpendicularly to the plantar aspect of the foot. The probe is then positioned to the mid-point of the true foot length, which is between the end of the 1st metatarsal and the end of the calcaneus. The participant will be asked to flex their 2nd-5th digits downwards against the operator's hand to ensure the correct muscle body is measured. Images are acquired and this process will be repeated three times, with average measurements taken for increased reliability. The Archercise device protocol is unique to this study and is as follows: Participants will be seated and shown the Archercise device and receive an explanation of how it functions. They will then be guided to perform four main exercises measuring: 1. Speed: Rapid raising and lowering of the arch 2. Endurance: Holding of the raised arch 3. Arch Elevation: Slowing raising the arch 4. Arch Lowering: Raising the arch and then slowing lowering it An explanation and demonstration of each exercise will be performed before measuring, with participants able to practice before testing to ensure correct measurements are taken. Each exercise will be performed three times for 30 seconds, with average measurements taken to ensure reliability, with a 5-minute break provided in-between exercises to recover or until the participant is ready to continue to the next exercise.