Electromyographic Responses of Tetraplegics
Electromyographic Responses Of Tetraplegics During Leg Cycling And Training
J. W. Priest, R. D. Hagan, FACSM, D. Bruce*, and R. Jennings*, Dept of HPE, Tarleton State University, Stephenville, TX
Surface electromyography (EMG) was used to record muscle activity in spinal cord injured (SCI) individuals prior to (PRE) and after (PST) 12 wks training (19±3 sessions) on the PsycleTM (Intellifit, Inc., Bedford, TX). SCI subjects included 3 complete (C) and 4 incomplete (IC) tetraplegics. During training, power output, session duration, and heart rate averaged 4.4±1.8 watts, 63±20 min, and 102±14 bpm, respectively. Mean peak EMG responses were recorded at 100 Hz (Telemyo system NORAXON U.S.A., Inc., Scottsdale, AZ) from the gastrocnemius (GAS), anterior tibialis (AT), hamstrings (HAM), rectus femoris (RF), erector spinae (ES), external oblique (EO), rectus abdominus (RA), and latissimus dorsi (LAT) during three treatments (TRM): seated rest (SR), passive assisted cycling (PAC), and active unassisted cycling (AUC). ANOVA with repeated measures revealed EMG activity increases (p<.05) for IC during AUC in HAM (113±57 µV) and RA (41±7 µV), but none in C (9±5 and 11±3 µV, respectively). EMG activity increases (p<.05) occurred from SR to PAC to AUC in GAS (4±1, 36±35, and 75±89 µV, respectively) and EO (15±9, 23±6, and 71±63 µV, respectively) for both C and IC. Following training, ES decreased during AUC from 121±47 to 65±38 µV in IC and remained unchanged in C (15±3 µV). EMG activity for RF (26±33 µV), AT (25±26 µV), and LAT (112±156 µV) for C and IC was similar across TRM and PRE/PST. Our findings reveal that during AUC, C tetraplegics have increased EMG activity in the GAS and EO, while IC tetraplegics have increased activity in the HAM, GAS, RA, ES and EO. With training, IC tetraplegics reduce ES activity.
*Psycle is a registered trademark of Intellifit Incorporated