Effects of resistance training in humans on neck muscle performance, and electromyogram power spectrum changes

The purpose of this study was to quantify the neuromuscular cervical adapta tions to an 8 week strength training programme. Seven healthy men, with no pathological conditions of the neck, performed a lateral flexion isometric resistance-training programme three times a week. The training sessions con sisted of one set of ten contractions, each of 6 s duration, at 60% of the predetermined maximal voluntary isometric torque (MVTim (warm-up) and two s ets of eight contractions, each of 6 s duration, at 80% MVTim,,. The traini ng effects were evaluated in three ways: muscle size, strength and fatigabi lity. The cross-sectional areas (CSA) of the trapezius (TRP) and sternoclei domastoideus (SCM) muscles were determined using a computerised tomographic scanner. Results showed an increase in the CSA of TRP and SCM muscles afte r training, 8.8% at C5 level and 6.4% at C7 level for SCM muscle and 12.2% at C7 level for TRP muscle. Strength increased significantly under both iso metric and isokinetic conditions (35% and 20%, respectively). Muscle fatiga bility in lateral flexion was quantified during a sustained isometric contr action at 50% of MVTim The shift of the mean power frequency of the electro myogram power spectrum density function of SCM muscle toward lower frequenc ies was less after training (14.6% compared to 6.8%). These results indicat e the beneficial effect of a strength-training programme which increases ne ck muscle size and strength during lateral flexion, and decreases the fatig ability of the superficial muscles of the neck.