During muscular contraction, if the tension developed by the muscle while shortening at constant speed is maximal over the full range of motion, it is called
Isokinetic contraction
Understanding Muscular Contraction Types
Muscular contraction is the process by which muscle fibers generate tension. There are different ways muscles can contract, depending on whether their length changes and how much force they generate.
Analyzing the Question: Muscular Contraction with Maximal Tension at Constant Speed
The question describes a specific type of muscular contraction where:
- The muscle is shortening (concentric action).
- Tension developed is maximal.
- The shortening occurs at a constant speed.
- This maximal tension is maintained over the full range of motion.
Let's look at the given options to determine which one matches this description.
Exploring Different Types of Muscular Contraction
Isotonic Contraction
Isotonic contraction occurs when a muscle changes length while generating tension. There are two types:
- Concentric Contraction: The muscle shortens while generating tension (e.g., lifting a weight).
- Eccentric Contraction: The muscle lengthens while generating tension (e.g., lowering a weight slowly).
In standard isotonic contractions, the load is constant, but the speed of movement and the tension the muscle can generate often vary throughout the range of motion due to factors like muscle length and leverage.
Isometric Contraction
Isometric contraction occurs when a muscle generates tension but does not change length (e.g., holding a weight in a fixed position). The tension is developed, but there is no movement.
Eccentric Contraction
As mentioned above, eccentric contraction is a type of isotonic contraction where the muscle lengthens under tension. This doesn't fit the description of the muscle "shortening".
Isokinetic Contraction
Isokinetic contraction is a dynamic muscular contraction where the muscle shortens or lengthens at a controlled, constant speed throughout the full range of motion. Specialized equipment (like an isokinetic dynamometer) is typically needed to ensure the speed remains constant. As the muscle contracts or extends at this fixed speed, the equipment adjusts resistance to allow the muscle to generate maximal tension at every point in the range of motion. This directly matches the description in the question: maximal tension developed while shortening at a constant speed over the full range of motion.
| Type | Length Change | Speed | Tension | Common Context |
|---|---|---|---|---|
| Isotonic (Concentric) | Shortens | Varies (load constant) | Varies | Lifting a weight |
| Isotonic (Eccentric) | Lengthens | Varies (load constant) | Varies | Lowering a weight |
| Isometric | No Change | Zero | Developed | Holding a plank |
| Isokinetic | Shortens or Lengthens | Constant | Maximal possible at speed | Specific testing/rehab equipment |
Conclusion
Based on the analysis, the type of muscular contraction characterized by maximal tension development while shortening at a constant speed over the full range of motion is Isokinetic contraction.
Revision Table: Muscular Contraction Concepts
| Term | Key Characteristic | Movement |
|---|---|---|
| Isotonic | Constant load | Muscle length changes |
| Isometric | Constant length | Tension developed, no movement |
| Isokinetic | Constant speed | Maximal tension throughout motion |
Additional Information: Isokinetic Exercise
Isokinetic exercise is often used in physical therapy and athletic training for rehabilitation and strength assessment. Because the speed is controlled, it allows muscles to be worked maximally throughout the entire range of motion, which can be beneficial for targeting specific weaknesses and improving overall strength and power at different joint angles. The resistance provided by an isokinetic machine is accommodating, meaning it matches the force applied by the muscle at that specific speed.
Important Questions from Exercise
- Which of the following is the most rapidly available source of energy within a muscle fibre?
- The forced vital capacity that can be expired in one second, is termed as
- Active isolated stretching is
Given below are two statements, one labelled as Assertion (A) and the other labelled as Reason (R). Read the statements and choose the correct answer using the code given below.
Assertion (A): In non-endurance athletes, that is, athletes engaged in high-resistance type of activities, the stroke volume capabilities are no different from those of their non-athletic counterparts.
Reason (R): In these non-endurance athletes, cardiac hypertrophy is characterized by a normal sized ventricular cavity and a thicker ventricular wall.
Given below are two statements, one labelled as Assertion (A) and the other labelled as Reason (R). Read the statements and choose the correct answer using the code given below.
Assertion (A): The complete breakdown of a fat molecule yields about 460 ATP molecules. Fatty acid metabolism is directly associated with oxygen uptake.
Reason (R): Numerous interconversions are possible among the various food nutrients. The exception is fatty acids that cannot be used for the synthesis of glucose.
