The authors concluded that antagonist muscle stretching induces agonist muscle activation, but the changes in vertical jump height were not correlated with passive hip flexor compliance.
The non-significant EMG activity changes in the agonist muscles following antagonist stretching found in the current study supports the idea that antagonist static or dynamic stretching has no effects on agonist muscle performance.
The possible reasons for these observations are: (i) positive effect of dynamic stretching on agonist muscles
by allowing a greater number of cross-bridges to form, resulting in an increase in force production, which causes a higher PAP and (ii) an effect of stretching on antagonist muscle by a declining muscle-tendon unit stiffness and formation of a less number of cross-bridges.
Thus, the second possibility that the contractile intensity of agonist muscles
is held in check for some reason when they are employed to accelerate sub-maximal weights must be considered.
We developed a hybrid training system (HTS) that combines electrical stimulation and volitional contractions; it uses the electrically stimulated eccentric antagonist muscle contractions as a resistance to voluntary agonist muscle
Resistance equal to that of the patient is an isometric contraction and increases tension in the agonist muscle
but without movement; this is associated with increased strength or tone of this muscle.
Previous studies (3,8,26) have shown a potential effect of PS on agonist muscle
performance due to the possible reduction in antagonist coactivation, storage of elastic energy, and alteration of the triphasic pattern of muscle activation.
The key finding from the current study was the significant increase in agonist muscle
performance during the SR exercise after contract-relax PNF stretching on antagonist muscles (shoulder adductors) compared to the TP.
According to the pain adaptation model, (24) pain causes a reduction in the activity of agonist muscles
and an increase in the antagonist activity which should lead to an increase in the percentage of co-activation.
The present data show that interventions based on strengthening agonist muscles
or decreasing the resistance of antagonist muscles through low-intensity stretching are beneficial in the development of both active and passive ranges of movement and provide functional training techniques that are often overlooked in favor of the more conservative moderate-intensity stretching programs.
These results are in agreement with several studies that reported a decrease in force production after SS of the agonist muscles