Effect of velocity on muscular coordination during isokinetic lifting: a preliminary study on healthy subjects

2. Methods In this study, 10 male volunteers (age: 38 ^ 5 years, height: 180 ^ 6cm, weight: 74 ^ 10kg) without previous history of low back pain participated. Each participant carried out three consecutive isokinetic lifting‐lowering cycles at five linear velocities: 0.26, 0.39, 0.52, 0.65 and 0.79ms 21 (Lift Simulation, Biodex System 4 Pro, New York, USA). The lifting was carried out as fast and strongaspossiblebetweenastandardisedstarting(thearms extended with the shoulders above the bar positioned just below the patella) and final (standup with the arms extended) position, while the lowering was passive. Except for the starting andfinal positions, no instruction was given to the subjects relating to the lifting technique. Surface myoelectric activity was continuously recorded (sampling rate: 2000Hz, Delsys Myomonitor IV, Boston, MA, USA) on 14 muscles (TB,triceps brachii; DS, deltoideus pars spinalis; TZ, trapezius pars descendens; ES, erector spinae at T3, T12 and L4 level; LD, latissimus dorsi ;G max, gluteus ;S T,semitendinosus ;B F, biceps femoris ;R F,rectus femoris; VL, vastus lateralis; GL, gastrocnemius lateralis and TA, tibialis anterior) during the lifting – lowering cycles. All EMG data were band-pass filtered (20 –400 Hz), rectified and low-pass filtered at 5 Hz. The two last lifting –lowering cycles were time normalised (2 100% to 100%, with 0 as the final position).