Related Experiment Video
Updated: Jul 6, 2026
05:52
Lower-Limb Biomechanical Characteristics Associated with Unplanned Gait Termination Under Different Walking Speeds
Published on: August 25, 2020
Changing the demand on specific muscle groups affects the walk-run transition speed
Jamie L Bartlett1, Rodger Kram
1Locomotion Laboratory, Department of Integrative Physiology, University of Colorado, Boulder, CO 80309, USA. bartletj@colorado.edu
The Journal of Experimental Biology
|April 1, 2008
Summary
Altering muscle demand affects the preferred walk-run transition speed (PTS). Reducing muscle effort increased PTS, while increasing effort decreased it, suggesting muscle-specific factors influence this gait change.
Area of Science:
- Biomechanics
- Human locomotion
- Muscle physiology
Background:
- The transition between walking and running is a fundamental human movement.
- Muscle-specific factors are hypothesized to trigger the walk-run transition.
- Understanding these factors is key to comprehending gait regulation.
Purpose of the Study:
- To investigate if altering muscle demand influences the preferred walk-run transition speed (PTS).
- To test the hypothesis that reduced muscle demand increases PTS and increased demand decreases PTS.
- To explore the role of specific leg muscles in gait transition.
Main Methods:
- Determined preferred walk-run transition speed (PTS) using a step-wise protocol.
- Assessed PTS with external devices that decreased or increased muscle demand.
- Measured electromyographic activity of five leg muscles (tibialis anterior, soleus, rectus femoris, medial and lateral gastrocnemius).
Main Results:
- Decreasing muscle demand significantly increased PTS.
- Increasing demand on plantar flexor muscles decreased PTS.
- Combining assistive devices did not yield a faster PTS, indicating other factors are involved.
Conclusions:
- Altering the demand on specific muscles can modify the preferred walk-run transition speed.
- While muscle demand plays a role, its effect is not simply additive, suggesting other underlying factors govern PTS.
- This research provides insights into the neuromuscular control of gait transitions.
Related Concept Videos
01:27Exercise and Muscle Performance
Exercise induces a range of adaptations in muscle tissue, depending on the type and duration of activity. Such physical training can be broadly categorized into two types: endurance exercises and resistance exercises.
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
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...
01:22Muscle 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...
01:28Muscles of the Leg that Move the Foot and Toes
The human leg comprises an intricate system of muscles that facilitate the movement of feet and toes. Within this system, the muscles are categorized into the anterior, lateral, and posterior compartments, each with a unique set of muscles carrying out specific functions.
Anterior Compartment
The anterior compartment includes muscles that contribute to the dorsiflexion of the foot. This compartment houses the tibialis anterior, extensor hallucis longus, and extensor digitorum longus muscles.
Anterior Compartment
The anterior compartment includes muscles that contribute to the dorsiflexion of the foot. This compartment houses the tibialis anterior, extensor hallucis longus, and extensor digitorum longus muscles.
01:48Classification of Skeletal Muscle Fibers
Skeletal muscles continuously produce ATP to provide the energy that enables muscle contractions. Skeletal muscle fibers can be categorized into three types based on differences in their contraction speed and how they produce ATP, as well as physical differences related to these factors. Most human muscles contain all three muscle fiber types, albeit in varying proportions.
Slow-Twitch Muscle Fibers
Slow oxidative, muscle fibers appear red due to large numbers of capillaries and high levels of...
Slow-Twitch Muscle Fibers
Slow oxidative, muscle fibers appear red due to large numbers of capillaries and high levels of...
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,...