Risk factors and practical issues Flashcards
How could changes in internal geometry cause an acute and chronic injury?
What factors influence changes to internal geometry?
For example, changing angle during the strike phase whilst running changes in the internal geometry, meaning the bones and tendons designed to take the force cannot accommodate the large load, causing acute ankle injury
If this improper internal geometry is repeated it may cause chronic injury
factors include flexibility, muscular imbalance or poor muscle activation.
How can strength training improve flexibility?
Elastic structures are stiffer than other parts of the muscle.
Exercises or even better- compound exercises under load through full ranges of motion elicit bigger and stronger elastic structures and stronger bone attachments, all of which contribute to improved ROM and thus flexibility. This is because you are able to to moving through larger ROM with strength, whilst simultaneously not causing damage or neural inhibition..
Describe the relationship between passive elastic moment and joint angle?
How might this relationship be different between athletes from different sports?
During the neutral position of a joint, the passive elastic load is close to zero. However, as you move the joint toward the peak ROM in any direction, the passive tissues become stiff, increasing the passive elastic moment so much so that the movement eventually becomes stopped; also from the bones locking in that joint.
Athletes of all sports eventually move toward similar passive moments at the end of ROM, due to bones locking. However, athletes like gymnasts have a greater range of motion (characterised by small passive moments across a larger ROM).
How are muscle imbalances caused and how can imbalances cause injury?
Postural alignment is maintained via the resting lengths of opposing soft tissues: flexors and extensors producing opposing forces.
However, imbalances occur when there is a strong agonist and weak antagonist. This changes the alignment and direction of the force (internal geometry)
Over time, the passive structures that are constantly being used to provide forces for the weak antagonist develop wear and tear, which can lead to chronic injury.
How was muscle imbalances in swimmers illustrated in the literature and the lecture?
A survey of 1262 swimmers in the usa reported that shoulder pain was high. And highest amongst national level (26%) and age group (10%).
Further studies on elite level simmers (McMaster et al., 1993; Sein et al., 2010) reported high percentages of shoulder pain- 40% and 91% respectively.
However, correlations are not causation. In response to this, studies found that shoulder muscle imbalances in swimmers developed over the course of training cycles. Therefore, greater training loads cause imbalances, these then cause shoulder pain and injury.
How do hamstring injuries typically occur? and according to a systematic review, what were the rist factors for hamstring muscle strain?
What are ways of measuring muscle imbalances?
Hamstring acute injuries typically occur an eccentric movement
The evidence suggests that older age, increased quad peak torque and past history of hamstring injury were main risk factors of hamstring strain.
Isometric Concentric:concentric Concentric:Eccentric Angle specific Angle and angular velocity specific
Why is the H:Q ratio typically not associated with increased risk of hamstring strain?
H:Q ratio can have a huge variation dependant on the torque, angular velocity and joint angle chosen. this varying, however, doesn’t suggest injury risk is high at a given ratio.
Why is pre activation and co-contractions so important to injury prevention?
What studies (hashemi et al. 2010 and unnamed) report in regard to pre activation and co contraction?
It takes time to develop force, it takes longer to express that onto an object, and longer still for the object to accelerate. Within this delayed time there is a high risk of injury as the muscles are not equipped to deal with any forces.
The body pre-activates muscles (co-contractions between antagonist-agonist pairs) in response to this. For example, a jumper will contract leg muscles prior to landing. The legs are producing force and the tendon is stiff (out of the toe region). When your muscles are ‘switched on’ and working the nervous system is better able to monitor them. All these factors work to deal with external forces better and prevent injury.
Hashemi et al., 2010 reported that increasing pre-activation of the quads protects the ACL during landing phase of jump in vitro
The drop landing and drop jump paper showed that jumping from a certain height without pre activation means there is not enough time to activate muscles upon contact and result in falling over.
1) What are the benefits of a warm up?
2) How is warm up best accomplished?
3) How does muscle temperature increase?
1) raise temperature of blood, muscles, tendons and ligaments
- warm muscles contract more forcefully
- relax quicker
- increase speed and strength
- warm blood means easier oxygen exchange
prepares bodies freely movable joint structure for PA while reducing injury risk
ROM increased due to muscle-tendon viscosity- more responsive muscle fibres.
2) Best accomplished with full body rhythmic activity before exercises that go through full ROM
3) Friction, metabolism and blood. Externally from heat sources or ultrasound.
Friction caused by injury- causes more damage. not good.
What did De Ruiter and De Haan (2001) report when measuring the force-velocity relationship on muscle at different temperatures?
Warm muscle was should to produce the largest angular velocities and forces.
Name the findings of Wright and Johns (1960):
Knight et al., 2001:
Safron et al 1988:
Wright and johns 1960:
- warmed joint to 113 degrees farenheit= ROM 20% increase
- cooled to 65 degrees farenheit= ROM decreased 10-20%
Knight et al., 2001:
Stretching after surface or ultrasound heating resulted in better ROM- ultrasound was best.
Safron et al., 1988: Warm up increased M/T elasticity in animals.
What evidence is there that stretching does not elicit benefits in sports before or after activity?
Thacker et al., 2004: systematic review of the literature assessing the evidence for stretching in injury prevention found no association
Herbert an Gabriel (2002): systematic review assessing effects of stretching on muscle soreness up to 3 days after exercise found no conclusive data.
Pope et al., 1998 and 2000: assessing stretching before and after exercise found no effect to the probability of injury
What is post activation potentiation?
What are PAPs benefits?
Does PAP training result in improved performance over time?
PAP is using maximal or near maximal efforts for a short duration immediately before exercise
Its benefits include:
Enhanced sub maximal efforts, RFD and power
However, too much can result in fatigue- bad.
PAP can result in chronic gains. However, this effect is just a result of increased total load per session instead of the mechanistic benefits of this training method.
What is vibration training?
What do vibrations do?
what are the supposed benefits?
Vibration training is performing body weight exercises on a plate providing controlled amps and frequencies
Vibrations do:
- evoke reflex responses and affect muscle
- Affect blood flow, sensory and other things
through the vibrations your muscles will contract between 30-50 times per second. Ensuring you are using 95% of muscle fibres whilst you are training on the plate. As opposed to the 65% via conventional training.
