## 4 Dynamic Assessment of Movement Performance
### Strain Gauges in Instrumented Sports Equipment  
The pressure sensors are operated through strain gauge sensors embedded inside the external sports tools such as paddles. These sensors measure the device's applied or received external pressures, enabling the detection of resistance changes in static, kinetic, or dynamic modes [24; 75]. In the sports research of the strain gauges, ref. [24] operated this modern device for Kayak water sport. They mounted a strain gauge inside both the paddle and footrest to measure the forces acting on them. So, they can evaluate the crew's performances by computing other parameters (e.g., stroke frequency) or consider these measurement results with acceleration and roll, yaw, and boat pitch obtained by GNSS and IMU, respectively. The advantage of this experimentation in the pilot study is to analyze the boat motion in both dynamic and kinematic pathways, the kayak propulsion study, and the paddling technique of the athletes. In the same area of performance analysis in skiing, it is valuable to understand the snow and skier interactions. The attached strain gauge under the ski surface was allowed to measure the load evolution during turns, torque, and force distribution between the left and the right leg during the alpine skier's progress.  
Additionally, this research area is beneficial to designing ski boots and bindings to enhance the athletes' approach [76]. The embedded strain gauge between the top of the tennis racket handle and the shaft bottom measured the estimated impact force in tennis forehand stroke. In the same area of research, the benefit can be understanding the technique to execute the tennis ball to reach the optimal speeds and modify a player's stroke technique [77]. In golf, more flexible shaft bending during the golf swing has a direct effect on making a more significant contribution to clubhead speed due to increasing the angular velocity at the grip. Via embedding the strain gauge inside the shaft of the golf stick, the data of the magnitude of shaft strain during the swing, rotation, and change in the shaft strain profile are accessible to aid in providing custom-fit clubs to golfers [78].  
Performance awareness, sports posture, and medical injury analysis via applied pressure and force on the pedal-based strain gauge are advantageous to understanding the cyclist sport discipline and bike design to enhance performance and reduce injury risks. Configuration of the strain gauge on the pedal and correct set-up to discover the linear relationship between strain and force on the pedal shaft led the designers to produce the equipment and guide the coaches and athletes in their analysis sessions by measuring 3D applied forces on the pedal in the outdoor and laboratory conditions to allow to record pedal force patterns in actual conditions [79; 80]. In [81], the deformation and elasticity of the pedal were measured via embedded strain gauges to determine 3D pedal loads for cyclists. The strain gauges were attached in the sagittal, frontal, and transversal planes to collect data on the medial-lateral, proximal-distal, and vertical forces. The injury risk is dependent on cycle design, cyclist posture, and seat type that occurs in the bottom area, knee and low-back pain, and, via strain gauge device, it is possible to measure the crank arm forces to explore standard pedal cycles related to the overuse injuries and muscle fatigue.