Beef tenderness exhibits a high and uncontrolled variability, which is one reason for the consumer's dissatisfaction. Moreover, the beef industry does not have predictive tools to measure meat tenderness. During the last few years, the impact of muscular characteristics such as collagen, lipids, proteolytic systems and fibres on meat tenderness has been studied. However, there is still an uncontrolled highly variable meat tenderness even when these muscular characteristics are under control. In order to understand this variability, some genomic studies have been conducted during the last 10 years. They allow the screening, without a priori, of genes and proteins whose expression is variable with meat tenderness. These studies have established a list of tenderness biomarkers whose phenotypic analyses can complete the polymorphism analyses. This article summarizes the current knowledge concerning the phenotypic approach, and will be followed by a second article which will present the genetic approach of beef tenderness markers.