Emerging evidence suggests that variation is inherent within a functional movement such that no movement is never performed the in the same way twice. That ‘normal’ movement patterns may not exist and that to attempts to ‘retrain ideal movement’ for purposes of musculoskeletal rehabilitation may be erroneous. This has led to criticism of biomechanical approaches to movement rehabilitation. Is it time to re-evaluate the standard biomechanical model?
In a biomechanical model it is assumed that patho-mechanics and repetitive use of poor movement patterns predispose pain and injury. Movement is subjectively evaluated based on levels of pain, symmetry, range of motion, strength and balance. Pain is thought to arise from excessive variation in movement away from a ‘normal’ or ‘ideal’ movement pattern due to increases in biomechanical stress and imbalanced tissue loading. Biomechanical intervention seeks to normalize movement patterns to recover from or reduce likelihood of injury, for example maintaining spinal alignment during lifting.
There is evidence of altered movement patterns and motor recruitment with injury. For example, lateral ankle sprains alter activation patterns of ankle muscles long after the initial injury, causing motor instability, and increased likelihood of re-occurrence of injury. But for standard biomechanical models to be valid basic assumptions have be met, these include that:
- Normal patterns of movement exist
- That pain is related to performance of motor tasks
- That motor patterns trained in clinical setting will transfer to patterns if daily movement
- That changes in motor patterns will impact upon the patient’s levels of pain
These assumptions are contentious based on the research literature. Research is now indicating that highly skilled performers never perform a motor skill the same way twice. Advances in neuroscience suggest that pain is a highly complex bio-psycho-social phenomena that is rarely proportional to either the degree of tissue damage or to the skill demonstrated in a motor task.
In future articles we analyze each of these assumptions to see to what degree they are both plausible and backed by the research evidence.