A Simple Method for Measuring Force, Velocity, Power and Force-Velocity Profile of Upper Limbs

Abstract

Upper limb abilities can be assessed from different kinds of exercises (e.g., cranking, push-up, and medicine ball put test). Since the bench press is a very common exercise used in training routines by most athletes in many sports, its interest in the scientific literature raised in the past two decades. As presented in previous chapters during jumping or cycling, from several bench presses performed against different loads, coaches and athletes can simply and accurately define their upper limb force-velocity (F-v) profile. They can estimate their theoretical maximal force (F ₀), velocity (V ₀) and power (P _max ). The aim of this chapter is to present the important points that must be taken into account to optimize the use of the bench press as a routine testing. In a first part, this chapter will focus on the importance of taking into consideration all the mechanical inertia involved in the bench press exercise. Not considering the upper limb mass in the calculation of the force produced during the exercise implies an underestimation in the F-v profile that can reach 30% for P _max . This could conduct to incorrect choices in the optimal load during training and thus limit the performance improvement. In the second part of this chapter, we present a simple mechanical model of the bench press to study the importance of the upper limb acceleration in the estimation of the force produced. The moving system (i.e., lifted mass and upper limbs) is modeled from rigid segments and the force can be determined thanks to four simple measurements: the vertical displacement of the lifted load, the elbow angle measured using a goniometer, the arm and forearm lengths and the constant horizontal position of the hand on the barbell. The validity of this model has been confirmed through experimental data obtained from a force platform. An important point is that the kinematics and kinetics of this model allow demonstrating that the acceleration of the moving system is similar to the one of the barbell. Finally, based on the previous statement, the last part of this chapter presents a simple method for assessing force, velocity and power during a ballistic bench press performed on a traditional guided barbell, based on the Newtonian laws and only three simple parameters: (i) upper limb mass estimated as 10% of the body mass; (ii) barbell flight height recorded with a nylon cable tie and (iii) push-off distance measured with a measuring tape. Consequently, coaches and athletes could accurately determine their F-v profile and extrapolate reliable mechanical parameters (F ₀ , v ₀, Sfv and P _max ) in order to maximize upper limbs performance and manage training programs in field conditions.