Objective: Assess and monitor changes in motor unit control of concentric and eccentric contractions during strength training repetitions in upper-limb curls.
This easy to use and non-invasive assessment of motor unit behavior provides a new level of information to understand the factors that influence muscle strength and optimize training interventions.
The Biceps and Triceps muscles of the upper arm were studied during repeated curls exercise.
Motor unit data revealed specific modulations in the strength of motor unit activation – measured by calculating the mean firing rate curves of each motor units indicating the number of firing per seconds of each motor unit – during each repetition and within repetitions.
The peak activation of all motor units (shown for one specific repetition on the left side) was lower during the eccentric vs. concentric phase.