Use of EMG analysis in challenging kinetic chain terminology

The purpose of this study was to compare mean integrated electromyographic values (EMG(int)) during biomechanically comparable closed kinetic chain/fixed external load, open kinetic chain/moveable no load, and moveable external load exercises.

EMG(int) were obtained for the pectoralis major (PM) and the long head of the triceps (T) during absorption and force phases of three biomechanically comparable exercises: the push-up (PU); the bench press-load (BP-L); and the bench press-no load (BP-NL) equated to the closed kinetic chain/fixed external load; moveable external load; and open kinetic chain/moveable no load conditions respectively. A force plate was used to equate load for the PU and BP-L exercises. Ten males (24+/-4.4 yr) participated in the three randomly ordered exercises. A pronated, closed grip was used for all exercises. The mean integrated EMG values from three isometric maximal voluntary contractions were used to determine a reference EMG (EMG(MVC)) for each muscle. Normalized EMG values (NEMG) were determined by EMG(int)/EMG(Mvc) and analyzed by one-factor repeated measures ANOVA for each muscle (PM and T) during each phase (absorption and force).

There was no significant difference (P > 0.05) between the equivalently loaded, different boundary exercises (PU and BP). Statistical significance (P < 0.05) was determined between the differently loaded, equivalent boundary exercises (BP and BP-NL) as well as the differently loaded, different boundary exercises (PU and BP-NL).

Results from this study support the theory that activities of similar biomechanical motions and mass of loading, regardless of the boundary condition, have comparable EMG values of primary muscle groups. In addition, this study suggests external load is more important than boundary condition in describing human activity.