Muscle Mechanics 2 Flashcards
Define Muscular strength
- The maximum force or tension produced by a muscle or muscle group at a site of attachment
- Is defined as ‘the peak force or torque developed during a maximal voluntary contraction’
Explain how morphology and neural factors can affect strength
Morphology
- Where a muscle’s strength is related to it’s cross-sectional area
- A larger muscle has greater force production capacity than a smaller muscle
Neural factors
- Motor unit recruitment leading to action potential
- Rate coding = frequency of signal travelling to motor unit (influences the force and tension in mm)
Strength is also influenced by other factors. List and explain several of these.
- The no. of motor units activated
- The size of such motor units (no. of mm fibres)
- The size of individual mm fibres
- The % of fast twitch fibres
- Frequency of motor unit stimulation
- The length of mm fibres
- The type of mm contraction
- The angle of mm pull
- How big your muscles are and the neurological ability to recruit fibres contribute to strength
Define Muscle power.
Power = (force x distance) / time also = speed x strength
How can muscle power be increased?
- Can increase power by increasing speed, increasing strength and/or increasing coordination of speed and strength interaction
- Must be an optimal speed of muscle shortening at which the most powerful contraction is produced
Describe the relationship between muscle contraction , velocity and power.
- Power increases with increases in velocity only up to a certain point
- After peak power is achieved further increases in velocity result in a reduction in the power a muscle can generate
- Thus, the production of maximum power is dependent upon the production of optimum force and optimum velocity
How are strength and Power related?
- Strength / power help to discriminate between athletes of different performance levels
- Increases in strength / power capacity may immediately affect performance change
- Strength and power are separate entities
- An increase in strength may not necessarily result in an increase in power
What does the slope of force-time curve indicate and what is the significance of this measure?
The force-time curve indicates that higher forces allow for max strength to be reached faster
Discuss how Strength / Power changes can occur neurologically.
- Disinhibition: reduction of golgi tendon organ inhibitory mechanism
- Motor unit synchrony: ability of motor units to fire in a synchronised, coordinated fashion
- Early on we get strength gains more from neurological adaptation than we do with muscle hypertrophy changes
- Learning: ability of stabiliser muscles (antagonists) to switch off results in greater prime mover force / power
Discuss how Strength / Power changes can occur due to morphology changes.
- Hypertrophy: increase diameter of muscle fiber through cell size increase
- Fast twitch hypertrophy is greater than slow twitch
- Hyperplasia: splitting of muscle fibers
- Other adaptations to strength / power training
- Increased bone density
- Increased stiffness of tendinous structures through organised deposition of non-elastic materials
List several ways that strength / power adaptation can improve the SSC.
- Neural improvement
- Learning effect
- Synchronization of motor units
- Increased bone density
- Morphological changes
- Greater cross-sectional area
What is plyometrics?
- Plyometrics is a type of exercise training that uses speed and force of different movements to build muscle power.
- Prestretch is part of conditioning protocol (eccentric followed by concentric)
- Purpose is to improve velocity of performance
List and explain 4 principles of resistance training.
Specificity
- Incorporates the principle that we must train the muscles that are responsible for a particular activity at the velocity and through the range of motion at which that activity takes place during competition.
Overload/ Intensity
- % of max tension of muscle
- Incorporates the principle that we must work above ‘normal’ levels of activity to increase our capacity
Variation
- Example: strength increases can then be carried over into performance with appropriate training
- Importance of training muscle groups that aren’t necessarily used to perform an event thus aiding limb and segment stability, minimising muscle imbalance and maintaining optimal posture
Recovery/ Rest
- Adaptation does not occur instantaneously and that time must pass to allow improvements to occur
- Time must pass to allow removal of metabolic by-products so that an optimal local environment for metabolism can be re-established
Can resistance training be disadvantageous for an athlete? Explain your answer.
- The muscle gains strength only at the angle you use in the exercise
- During some exercises (isometric) the blood flow to the muscle stops, blood pressure rises, and less blood flows back to the heart (it could be dangerous if you have heart problems)
- Isometric training is not sufficient on its own, You need to combine it with isotonic training
Define flexibility.
Terminal ROM of a segment
