Evaluation of Isometric Strength and Hamstring/Quadriceps Ratio in Healthy CrossFit Subjects

Crossfit® is a high-intensity physical training plan based on a program that includes exercises such as running, weight lifting and gymnastic movements. It focuses on the development of 10 physical qualities: strength, balance, cardiovascular and respiratory endurance, coordination, power, flexibility, agility, speed, precision and muscular endurance.Unfortunately, research on its effects is still at the beginning. The time of each session is one hour, which is divided into a warm-up of 10-30 minutes, strength training or skills, endurance work and finally a recovery phase, mobility and stretching. These types of exercises are incorporated into group training sessions called Workout of The Day (WOD). Muscular strength is the action produced by a muscle or muscle group against resistance. It is one of the fundamental physical qualities for activities of daily living. Digital isometric dynamometry is a tool to evaluate maximum voluntary isometric contraction (MVIC). Hamstring muscles are responsible for hip extension and knee flexion. Moreover, they are the main protectors against anterior knee subluxation due to their action in conjunction with the anterior cruciate ligament (ACL).The quadriceps is one of the largest and most powerful muscles of the human body. The ratio between hamstrings and quadriceps muscles has a strong correlation with lower limb injuries. This ratio, known as "H:Q" has proved to be the most reliable indicator to quantify a neuromuscular decompensation that causes an injury and, in addition, it is used as a prognostic indicator.