No abstract

Electromechanical delay (EMD) values were obtained using a cross-correlation technique for a series of 14 repetitive submaximal dynamic isometric contractions of the vastus lateralis performed by five subjects. To avoid a phase lag, which is introduced with one-way filtering, the EMG was processed with a bi-directional application of a second-order Butterworth filter. A mean EMD value of 86 ms (SD = 5.1 ms) was found. Moreover, contraction and relaxation delays were computed and compared. There was a significant difference between the contraction and relaxation delays (P less than 0.005). The mean contraction delay was 81.9 ms and the mean relaxation delay was 88.8 ms. Despite this significant difference, the computed contraction and relaxation delay values lie in the same range as the total phase lag, calculated with the cross-correlation technique. The magnitude of EMD values found supports the need to account for this delay when interpreting temporal aspects of patterns of intermuscular coordination.

In experienced hands, the double dynamic graciloplasty is an oncologically safe procedure that can have an acceptable functional outcome in a well-selected group of patients. However, to improve the outcome, further modifications will be necessary. So far, the addition of a pouch has not resulted in improved outcome.

Eight well trained marathon skaters performed all-out exercise tests during speed skating on ice and roller skating. To compare these skating activities in relation to the concept of training specificity, relevant physiological (VO2, VE, RER and heart rate) and biomechanical variables (derived from film and video analysis) were measured. There were no significant differences between oxygen uptake (50.5 +/- 8.0 and 53.3 +/- 6.7 ml.min-1.kg-1), ventilation (102.4 +/- 11.2 and 116.0 +/- 11.1 1.min-1) or heart rate (174 +/- 12.2 and 176 +/- 14.5 min-1) between speed and roller skating. In roller skating a higher RER (1.16 +/- 0.1 cf. 1.05 +/- 0.1) was found. Power, work per stroke and stroke frequency were equal. Due to a higher coefficient of friction the maximal roller skating speed was lower. The effectiveness of push-off and parameters concerning the skating techniques showed no differences. In roller skating a 7.5% higher angle of the upper leg in the gliding phase occurred. It is speculated that the blood flow through the extensor muscles might be higher in roller skating. It is concluded that roller skating can be considered as a specific training method which may be used by trained speed skaters in the summer period.