The reversal of antagonists facilitates the peak rate of tension development.
OBJECTIVE
The present study was designed to test the effects of the reversal of antagonists on the peak rate of tension development (dF/dt(max)) of the elbow extensors.


METHODS
Experimental, with matched controls.


METHODS
A biomechanics research laboratory.


METHODS
Twenty-six healthy women without a history of upper extremity injury or neurologic disorder, randomly assigned to experimental (n = 13) or control (n = 13) groups.


METHODS
Two groups of healthy subjects followed identical exercise protocols, except that the control group performed maximal isometric contractions of the elbow extensors and the experimental group executed a maximal isometric elbow flexion contraction immediately before a maximal elbow extension contraction. Both groups performed 5 cycles of a 2-second contraction with 22-second rest periods between agonist muscle contractions and were evaluated at 4 test sessions spaced 2 weeks apart.


METHODS
All measurements were done with the shoulder and elbow at 90 degrees of flexion in the sagittal plane to ensure reproducibility. A load cell was used to measure elbow extension moment and to calculate the peak rate of tension development (dF/dt(max)). Biceps and triceps brachii surface electromyographic activity was monitored concurrently. The electromyographic measures were mean spike (peak-to-peak) amplitude and mean spike frequency of the biceps and triceps brachii activity.


RESULTS
Intraclass dF/dt(max) and electromyographic reliability was good (r > or = .72) in both groups. Because biceps electromyographic measures were considerably less reliable (r < or = .53), they were not included in our analysis. While dF/dt(max) increased quadratically in both groups (p <.05), the experimental group was on average 36.1Nm. s(-1) (63%) greater across sessions 2 to 4 (p <.05). In contrast, triceps electromyographic activity did not differ significantly between groups (p >.05). The means averaged across groups exhibited a quadratic increase from session 1 to session 4: 91microV or 48% for mean spike amplitude (p <.05) and 7Hz or 16% for mean spike frequency (p <.05).


CONCLUSIONS
The greater dF/dt(max) for the experimental group was not associated with increased electromyographic activity. The experimental group appeared to use the biomechanic properties of the pretensioned extensor muscle-tendon complex, rather than neurologic biasing, to accomplish its power gains.
Gabriel
D A
DA
Biomechanics Laboratory, Brock University, St. Catharines, Ont, Canada. dgabriel@arnie.pec.brocku.ca
Basford
J R
JR
An
K N
KN
D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D004550:Elbow / Q000502:physiology*; D004576:Electromyography; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D018482:Muscle, Skeletal / Q000502:physiology*