ScrumTruk offers significant advantages over traditional exercises typically used to develop leg strength for rugby. It aids in the training of specific muscle/joint actions, rapid adoption of sound technique, avoidance of lower back overload and encourages persistence with the exercise program.
In scrummaging the typical movement of both hip and knee joints is from 90° to 120°-130° of extension (full extension being 180°). In the past there have been three common multi-joint exercises used to train hip and knee extension. These are barbell squats, barbell dead-lifts and the leg-press.
The barbell squat is often referred to as the 'king of exercises' but it is one of the least popular and most frequently avoided exercises.
At the bottom of the squat movement there is a large amount of shear force about the discs of the lower back and structures of the knee due to the direction of loading compared to torso and limb alignment.
With vertical loading on a forward tilted torso it is difficult to display good form. Balance problems or lack of abdominal strength can produce poor technique and an inability to progress in the exercise or worse still cause injury.
With barbell dead-lifts this type of shear force loading is even more pronounced causing not only accentuated forward tilting of the torso but also flexion of the lower lumbar spine which can cause injury when even moderate loads are lifted.