Related Experiment Video
Updated: May 29, 2026
07:44
Construction of Constant-Load (Isotonic) and Constant-Velocity (Isokinetic) Torque-Velocity-Power Profiles In vivo for the Rat Plantar Flexors
Published on: October 3, 2025
Muscle power attenuation by tendon during energy dissipation
Nicolai Konow1, Emanuel Azizi, Thomas J Roberts
1Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA. nkonow@brown.edu
Proceedings. Biological Sciences
|September 30, 2011
Summary
Tendons act as crucial buffers during rapid muscle lengthening, absorbing impact energy. This tendon elasticity protects skeletal muscles from potentially damaging high velocities and forces during deceleration activities.
Area of Science:
- Biomechanics
- Skeletal Muscle Physiology
- Tendon Mechanics
Background:
- Skeletal muscles decelerate movement by lengthening to dissipate energy.
- The interplay between muscle contraction and tendon elasticity is vital for energy production.
- The specific role of tendon elasticity in energy dissipation by muscles is not well understood.
Purpose of the Study:
- To investigate the function of tendon elasticity during active muscle fascicle lengthening in energy dissipation.
- To test the hypothesis that tendon elasticity acts as a mechanical buffer, mitigating high velocities and powers during muscle lengthening.
Main Methods:
- Directly measured lateral gastrocnemius muscle force and length in wild turkeys during controlled landings.
- Utilized video kinematics to measure muscle-tendon unit (MTU) strain.
- Employed sonomicrometry to independently measure muscle fascicle strain.
Main Results:
- During initial impact and MTU lengthening, muscle fascicles showed minimal lengthening; joint flexion was primarily accommodated by tendon stretch.
- Following the initial impact phase, muscle fascicles lengthened, absorbing energy after most joint flexion occurred.
- Tendon recoil primarily drove the late muscle fascicle lengthening, reducing fascicle lengthening velocity and energy absorption rate.
Conclusions:
- Tendon elasticity functions as a significant energy storage mechanism during rapid muscle lengthening.
- Tendons act as power attenuators, likely protecting skeletal muscles from damage caused by forceful and rapid lengthening during energy dissipation.
Related Concept Videos
01:22Muscle Stimulation Frequency
The contraction strength of muscles is regulated by motor neurons, which modulate the frequency of action potentials dispatched to the motor units based on the body's requirements. This process of varying the muscle stimulation frequency allows muscles to contract with a force that is precisely tailored to the needs of the moment, whether lifting a feather or a heavy box.
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
01:24Muscle Recovery and Fatigue
Muscle fatigue refers to the decline in a muscle's ability to maintain the force of contraction after prolonged activity. It primarily stems from changes within muscle fibers. Even before experiencing muscle fatigue, one may feel tired and have the urge to stop the activity. This response, known as central fatigue, occurs due to changes in the central nervous system, namely the brain and spinal cord. While there is no single mechanism that induces fatigue, it may serve as a protective response...
01:25Energy Supply for Muscle Contraction
Skeletal muscle fibers have the unique ability to switch between rest and contraction states, using different sources of ATP for energy. The contraction cycle and Ca2+ transport back into the sarcoplasmic reticulum for relaxation require significant ATP. However, the ATP reserves in muscle fibers are limited and can only sustain contractions for a few seconds. Additional ATP production becomes necessary for prolonged contractions. As a result, muscle fibers generate ATP through various sources,...
01:20Motor Unit Stimulation
When the neuron of a motor unit fires an action potential, it triggers a series of events, leading to a twitch contraction in the muscle fibers. The process of excitation-contraction coupling is crucial in relaying the action potential to the muscle fibers.
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
01:26Cross-bridge Cycle
As muscle contracts, the overlap between the thin and thick filaments increases, decreasing the length of the sarcomere—the contractile unit of the muscle—using energy in the form of ATP. At the molecular level, this is a cyclic, multistep process that involves binding and hydrolysis of ATP, and movement of actin by myosin.
01:29Relaxation of Skeletal Muscles
The period of muscle contraction primarily influences the duration of stimulation at the neuromuscular junction (NMJ), the presence of free calcium ions in the sarcoplasm, and the availability of energy or ATP to support contractions.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.