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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. | 
