Dynamic Variable Resistance Training (DVRT™) is the most natural way to train. Why? The DVRT program and Ultimate Sandbag are designed to meet the way the body naturally moves. This means it can accommodate any fitness level and possess endless versatility. The highly engineered Ultimate Sandbag is your key to moving, feeling, and living better! DVRT Sandbag training is not simple about adding weight as a way to measure strength. In DVRT There are several ways to progress through movement that include holding position, weight, acceleration, tempo, sandbag dimension, three different planes of motion, body position, and combining these elements together gives endless possibilities to improve strength. There is a growing trend of military, fire fighters, police officers, martial artist, and professional fighters that are now using DVRT. The reason is that there is no other system when combined with the ultimate sandbag that will allow moment with an unstable object through all range of motions. It does not matter weather you are a special unit operator or an office worker the ability to move against resistance is the most important aspect of exercising. The ultimate sand bag and DVRT will improve your strength, endurance, but most importantly it will make you strong through movement.