The Study of Biomechanics
1. Capacity: Static (Quiet standing)
- A state of constant motion at rest or at a constant velocity.
- Forces controlled by contraction of proteins (actin and myosin).
- Creates the Force-Velocity relationship (muscles).
- TESTING: Muscle imbalance distorts alignment and sets the stage for undue stress and strain on joints, ligaments and muscles. Manual testing is the tool of choice when it comes to determine the extent of imbalance.
2. Capacity – Dynamic (Gait)
- A state where acceleration and deceleration are both present.
- Elongation of the connective tissue.
- Is a significant factor in affecting movement at the joint end ROM.
- TESTING: Today’s literature identifies many common themes regarding ‘why’ we should screen clients: to conserve energy by proper use of the body and it’s parts; to expend energy intelligently and efficiently to accomplish a given purpose; to sustain attention; allow the body the ability to move, engage and proprioceptively respond through desired rom/task without pain/discomfort nor errors in patterning; reduce pain due to wasted energy; and to reduce faulty mechanics therefore reducing some of the ageing processes (Methany, 1951; Carlsoo, 1972; Broer & Zernicke, 1979; Gabbe et al. 2004; Leard et al. 2009). Screening movement or movements that demonstrate control and efficiency has the capacity to reduce disease and dysfunction.
It is important we understand both these biomechanical systems if we want to reduce disease and dysfunction – Learn More
The Study of Movement
One area where anatomical description is quite effective is in the area of the range of motion used in movement. Movement can be accurately described as combinations of joint angular motions. Remember that the biomechanical principle of range of motion, however, can be more generally defined as any motion (both linear or angular) of the body to achieve a certain movement goal. Specific joint motions can be of interest, but so too can the overall linear motions of the whole body or an extremity. Coaches can speak of the range of motion of a “stride” in running or an “approach” in the high jump. Therapists can talk about the range of motion for a joint in the transverse plane.
In human movement the performer can modify the number of joints, specific anatomical joint rotations, and amount of those rotations to tailor range of motion. Range of motion in movement can be imagined on a continuum from negligible motion to 100% of the physically possible motion. The Range-of- Motion Principle states that less range of motion is most effective for low-effort (force and speed) and high-accuracy movements, while greater range of motion favors maximum efforts related to speed and overall force production (Hudson, 1989). A person playing darts “freezes” or stabilizes most of the joints of the body with isometric muscle actions, and limits the dart throw to a small range of motion focused on elbow and wrist. The javelin thrower uses a long running approach and total body action to use considerable range of motion to maximize the speed of javelin release. The great accuracy required in golf putting favors limiting range of motion by using very few segments and limiting their motion to only what is needed to move the ball near the hole.
Joint flexibility is a term used to describe the range of motion (ROM) allowed in each of the planes of motion at a joint. Static flexibility refers to the ROM present when a body segment is passively moved (by an exercise, partner or clinician), whereas dynamic flexibility refers to the ROM that can be achieved by actively moving a body segment by virtue of muscle contraction. Research indicates that these two components of flexibility are independent of each other. Although people’s general flexibility is often compared, flexibility is actually joint specific. That is, an extreme amount of flexibility at one joint does not guarantee the same degree of flexibility at all joints.
The desirable amount of joint flexibility is largely dependant on the activities in which an individual wishes to engage. Gymnasts and dancers obviously require greater joint flexibility than non-athletes however, these athletes also require strong muscles, tendons and ligaments to perform well and avoid injury. Increasing joint flexibility is often an important component of therapeutic and rehabilitative programs and program design to train athletes for a particular sport. Several approaches for stretching these tissues can be used, with some being more effective than others because of differential neuromuscular responses elicited. Static Flexibility is considered the better indicator of the relative tightness or laxity of a joint in terms of implications for injury potential.
So, how can we make sure we are manually testing of static and dynamic biomechanics is reliable?
The Study of Manual Testing
Important Methodology to Manual Testing
Studying human movement can be concerned with gross motor patterns or it can be confined to the details of fine motor control. Carlsoo (1972) sums up the screening considerations as ‘an attempt to analyse movement where one will find three different kinds of movement that are included in all cases;
- Postural movements
- Locomotor transfer movements, and
- Manipulating movements.
Current literature suggests manual and physical therapists often use a postural-structural-biomechanical (PSB) model to ascertain the causes of various musculoskeletal conditions (Knudson, 2007; Lederman et al., 2011). Any assessment, or screen, of movement skill must begin with the question ‘why?’ – not why does a person move in a particular way, but why do we assess movement skill in the first place?
A movement is often termed ‘right’ or ‘wrong’, ‘suitable’ or ‘unsuitable’, ‘efficient’ or ‘inefficient’ usually without any support for such designation; subjective evaluations of this kind are not satisfactory (Carlsoo, 1972). Describing movement as ‘right’ or ‘wrong’ has many concerns. Human beings are all distinctive; our somatotype, anatomy, and anthopometric measures are very individual. Individual to individual movement analysis will have a profound difference and therefore no two people can perform a skill in exactly the same way. Conversely, to understand how an ‘unsuitable’ or ‘inefficient’ force may negate performance and incite injury, whilst ‘suitable’ or ‘efficient’ forces can improve performance and prevent further injury, is an important element of studying human motion. As previously discussed, by applying reliable and robust assessment systems we can identify ‘unsuitable/inefficient’ movement as a ‘weak link’, whilst the ‘suitable/efficient’ movements are celebrated as ‘assets’.
However, variability is not necessarily random (Riley & Turvey, 2002) not always noise (Carlton et al., 1993) and is not always undesirable (Davids et al., 2006). These Motor Control Theorists believe that movement variability may occupy a functional role in human behaviour. They consider movement variability as an essential feature of human motor behaviour that affords the sensory system the necessary flexibility and adaptability to operate proficiently in a variety of performance, development and learning contexts. The theoretical approach of dynamical systems of motor behaviour places greater emphasis on the space-time characteristics of coordination patterns in tasks requiring the use of multiple biomechanical degrees of freedom (Davids et al., 2003). In dynamical systems theory, patterns of coordination emerge through generic processes of physical self-organisation rather than being prescribed by some sort of executing regulating agent (Carson et al.,1995).
Within this framework of thought, variability has been elevated from mere noise to be eliminated, to the driver of pattern change. For both injury and performance biomechanics, establishing variability profiles is now a major tool. Variability of movement patterns are related to the specific set of constraints acting upon the system. Constraints do not specify behavior, but limit the range of potential behavior for example; social and environmental influences, somatotype, task requirements, as a result these constraints are constantly changing. Variability adapts to local constraints and is able to change force application, consequently distributing load during repetitive movement and reducing injury. All this evidence indicates that an unskilled athlete will display low variability of movement leading to poor outcome, whereas a skilled athlete will display high variability of movement patterns as a result a higher consistent outcome. Although this is interesting when considering an assessment/screening process, there was no literature to validate quantity of repetitive movement required to justify at what stage Movement Theorists would desire variability.
5 Protocols to Manual Testing
1. To categorise or identify
- Validity for manual testing’ is defined as the appropriateness, meaningfulness and usefulness of the specific inferences made from test scores.
- Test validity is defined as the process of accumulating evidence to support such inferences (Standards for educational and psychological testing, 2003).
2. To plan treatment and/or corrective exercises
- Needed to change subjects neuroplasticity, hand them back the responsibility of their symptoms, to create new habits within the 168 hours in each week.
- If a movement cycle is to be corrected in accordance with the biological and mechanical laws governing man, it is necessary to use a scientific system, among the multitude of movements encountered, based on human anatomy and physiology (Carlsoo, 1972).
- These structures may be important for setting the particular parameters of the movement, such as the force and duration of movement and for controlling the movement in progress (Lephart et al., 1997; Hatze, 2000; Lee et al., 2006; Ward, 2010).
- Therefore, to ensure the subjects static and dynamic biomechanics organisation is optimal, it is important to also ensure each command given impacted upon their interpretation kinesthetically, visual and audible. The more often a movement is repeated, the more automatically and functionally it is performed (Carlsoo, 1972) and as a byproduct of movement strength and co-ordination are improved.
3. To evaluate change over time
- Re-assessment on concurrent sessions.
- Realistic goals and timelines.
4. To provide feedback
- Create a dynamic feedback ‘system’ offering the client an ‘easy to understand’ visual representation of their faulty mechanics risks and ‘assets’.
- Add information on the importance for the subject to recognise their ‘assets’ e.g. the things they did well with.
5. To predict
- To predict an injury prevention programme works is a highly controversial subject within the manual and physical therapist literature, however, there are studies that have suggested individuals with pain present with uncontrolled compensatory or aberrant movement patterns (Ludewig & Cook 2000; Knudson, 2007; Cook, 2010).
Next weeks Blog
- Exploring the tools in our tool box and how we would use them, and what we have been told they do for rehabbing the injury.
- How to rehab: MT/Pilates etc
- Injury Management (PRICE etc)
- Why what we do may not work? (gentle intro to Tissue Mechanics)
There are so many mechanisms involved in squatting, some of these mechanisms are fundamental to the human design, others blow off the cobwebs and allow us to keep moving safely and efficiently. Reducing squatting exposes the joints to premature aging; knees, hips, ankles, spine, and pelvis.
Thumb joint corrects foot pain! Seriously?I know, crazy right? I must be mistaken? It has to be some kind of black magic? I'm pain-free because of some other factor? It must be psychosomatic?To be honest, I have heard it all now. What's important? My wrist is pain-free enabling me to get back to a normal life after 2 years of pain!