Relationship Between Muscle Activation Sequencing and Segmental Motion During Punching
Paul K. Smith, Tim Niiler · Medicine & Science in Sports & Exercise · 2008
PURPOSE: To determine the temporal activation sequencing of selected agonistic and antagonistic musculature and the corresponding pattern of motion at the hip, shoulder and fist when impacting a makiwara punching board with a reverse punch. METHODS: Subjects (N=10, <1 to 34 yrs. experience), with EMG sensing electrodes placed on the agonistic/antagonistic pairs of rectus femoris/gluteus maximus, pectoralis major/middle trapezius and biceps brachii/triceps brachii were videotaped with one Sony digital video camera operating at 30 Hz while punching a makiwara punching board (www.ISKF.com). EMG signals for 26 trials, collected at 1000 Hz, full-wave rectified and linear enveloped (fcutoff=6 Hz), were processed using LABVIEW 8. Video data were processed using OpenTrack2d software to determine 2D kinematics. Data were evaluated from punch initiation to contact with the board. Hip, shoulder, and arm muscle activation times to impact (ms), measured from the first 10% rise in amplitude to board impact, were correlated with peak horizontal linear accelerations at the fist. RESULTS: Significant predictors (R2 = 0.637441, p<0.0001) for peak horizontal linear accelerations were the bicep brachii (p<0.0001), triceps brachii (p=0.0015), right erector spinae (p=0.0003), and the time from punch initiation to peak acceleration (p<0.0001). The best fit model for significant predictors was: CONCLUSION: The findings suggest that a sequential pattern of muscular activation from the trunk to the fist was present to obtain the highest fist accelerations. The bicep brachii and triceps brachii were the stronger predictors such that the earlier peak acceleration of the fist is reached, the higher it will be.