Related Experiment Video
Updated: May 9, 2026

Isometric and Eccentric Force Generation Assessment of Skeletal Muscles Isolated from Murine Models of Muscular Dystrophies
Published on: January 31, 2013
Isometric training with maximal co-contraction instruction does not increase co-activation during exercises against
Tarak Driss1, Virgile Serrau, David George Behm
1a Université Paris Ouest Nanterre La Défense , CeRSM (EA 2931), UFR STAPS , Nanterre , France.
Abstract:
The present investigation verified that strength is improved by a training programme consisting of repetitions of maximal isometric voluntary co-contractions without increasing co-activations during contractions against external resistances. Ten participants performed 12 training sessions (four sets of 6 × 4 second maximal isometric co-contraction of the elbow flexor and extensors, 3 days a week for 4 weeks). Surface electromyograms of triceps and biceps brachii were collected during maximal voluntary isometric elbow flexion and extension against a force transducer. Maximal voluntary isometric force increased significantly after training, by 13.8 ± 6.0% (extension) and 9.6 ± 9.5% (flexion), but the observed increases in EMG of agonist muscles during maximal voluntary contraction were not significant. No significant changes in the levels of co-activation of the elbow flexors and extensors were observed. No significant change was observed for all the parameters in a control group of ten participants. These results indicated that the strength improvements after co-contraction training occur without increases in co-activation level.
Related Concept Videos
Isotonic and Isometric Muscle Contractions
Isotonic contractions
Isotonic contractions occur when a muscle changes length while the...
Exercise and Muscle Performance
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...
Motor Unit Stimulation
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...
Excitation-Contraction Coupling in Skeletal Muscles
When an action potential...
Muscle Stimulation Frequency
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
Muscle Contraction

