The perspective that the body is an interconnected unit that displays regional interdependence is a valuable one. That different parts interact in different ways during different activities and influence ROM (range of movement) in other areas of the movement chain should seem a fairly easy link to make when looking at the whole body during different context dependent movements. We often eschew the value of the integrated system in favour of the isolated joint/muscle model.
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I had an interesting case this week involving a water polo player who was experiencing shoulder pain when throwing. This pain was only occurring however when he put maximal effort into the throw. Now I do not get to see many water polo players so this was a challenge. I decided to put aside the fact that ground reaction forces would be different as well as having two different resistances on the upper and lower parts of the body (air and water friction) as this would present even more challenges to the assessment!
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If you have ever looked at the biomechanics of the backswing in golf it becomes obvious that being ‘on plane’ is a perfect functional combination of the three planes of movement available to the body, sagittal, transverse and frontal. My recent foray into the world of video analysis with golf has inspired my post!!
This also kind of ties in with my friend Dave Westerman’s recent video explanation of biomechanics involved during the golf backswing.
When we may start to see problems is when the body does not have the capacity to move in the plane required. A strategy we may see is the body obtaining more movement in the plane it can get to compensate for movement in the plane that it can’t get.
The required motions in the backswing at the hip are extension (in a flexed position), ADDuction and internal rotation. The aim in the backswing is to not shift the Centre of mass to far to the right for a right handed golfer. The larger shift in mass and translation of the pelvis comes during ball striking and follow through. This acceleration of mass creates the force required to propel the ball.
A common swing fault can occur when instead of using the transverse plane to create relative internal rotation at the hip, we instead utilize frontal plane translation. This pushes our centre of mass over to the right for a right handed golfer.
What we now see is an inability to sequence correct motions in the swing. The shift in weight cannot be reversed in time so that the hips can create a proximal acceleration to provide additional load to the core, chest and shoulder. By the time the hands have started the down swing the hips are still lagging behind, unable to cover the range in the timeframe available. This frontal plane translation could also compensate for the ability to get opposite side lateral flexion. The shift in mass through hip motion creating more or the illusion of more lateral flexion.
This change in sequence can lead to inefficient and ineffective swing mechanics and also to injury to the tissue that relies on this correct sequencing. The lack of mass in the F=MA equation will also severely reduce power.
This is very similar to what happens during overpronation at the foot. The large motion and increased range into pronation means that the body is unable to reverse this motion into supination by the time the swing phase of gait is initiated. This leads to a back foot pronation and reduced movement in the rest of the kinetic chain.
As with all sport golf, relies on the sequencing of movements to accelerate our mass at the correct time. Our ability to understand our client’s function and our clients ability to perform their function is vital to our success.
Check out Cor-Kinetic facebook.com/corkinetic for loads more functional info and course dates.
This blog comes courtesy of a conversation I had with my good friend Mike. Its all about optimum range of a muscle. It kind of followed on from this piece of info…
The eccentrically-loaded muscle will start its contraction weak and then get stronger; the concentrically-loaded muscle will initiate strong, but get weaker as the contraction continues.
I had never given this much thought before but this makes a lot of sense when we think of length tension relationships. A muscle will struggle to produce force when both too long and too short. Being weak in both positions. Cross bridge attachment has an optimal range. This will be true of both force production and conservation of energy. Too much cross bridge detachment will also cause a more thermodynamically expensive scenario as we split ATP and dissipate energy as heat.
Elastic energy will also I believe have an optimal range. Studies have shown that spring stiffness (ability to return energy) comes from optimal joint angles or ranges. Going beyond this range means that we dampen or absorb energy, again dissipating as heat through visceoelasticity of tissue. Different tissues have varying levels of stiffness and compliance, different ranges will bring into play these different characteristics as will our neurological intention (land or jump again) to move control stiffness through efferent spindle stiffness regulation.
If we look at the way we jump when we want to jump again, we can see that we use a shorter joint range than when we land for the final time. When we finish we have a large bend of the knee to absorb ground reaction forces rather than reuse them. This has implications for our understanding of height, range and repetition programming for our training me thinks!!
Ecconcentric (both eccentric and concentric muscle contractions occurring in different planes) muscle action may also play a role in optimal cross bridge attachment. If a muscle was to lengthen in all three planes this may cause a scenario where we are going beyond the optimal range for the muscle in terms of force production and elastic energy recoil. By mitigating elongation of the tissue in a plane of motion through concentric shortening we may also keep an optimal range. It maybe this would happen in a more sub maximal scenario where energy return and energy conservation are more important than maximal force production. I feel that gait is a great example of this. Although maximal force production may also be mitigated by creating too much loading through joint range that is hard to transform.
This then got me thinking about how we train. Many times we are looking for maximal ranges in our training. Maybe we should be looking more at optimal ranges. This may have more implications for sports where we can control the range through skill however. Running is a great example. Controlling stride length will keep us within optimal joint ranges. We must also remember that optimal will be governed by the individual. This will be affected by tissue ability, limb length, speed ability and event. I expect it will be that different events within running e.g. 400 metres will need different joint ranges from a marathon as we balance need for all out power, power-endurance and endurance. Going beyond optimal means our ability to start the next phase of movement, either eccentric to concentric or vice versa, will be compromised. I think that deceleration and acceleration are part of running (unlike the pose method ideology!) However we can mitigate excessive amounts of both having to occur, increasing energy conservation.
If we look at a game of tennis it is much easier to hit a powerful shot when we can manoeuvre our bodies into position. When we are out of position our range of movement may have to be extended to reach the ball. The transformation from eccentric to concentric is sub optimal and affects the power of the shot. The tennis player many times at end range will hit a defensive shot back, aiming to get it in the court rather than a winner! Increases in amortisation from eccentric to concentric reduces cross bridge attachment also decreasing energy return. The closer we get to and stay at end range stretching for the ball the longer we have the amortisation phase reducing the energy gained in the loading motion.
This is a very theoretical piece and mainly my own thoughts (so blame me!!) but it may give us food for thought when we programme ranges/heights for our clients to move through when training.
More may not be better in all circumstances!!!
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