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Biomedical subjects

S H Roy

Publications and source records attributed to S H Roy.

23 records · Page 2Linked to original sources
PubMed1986

Median frequency of the myoelectric signal. Effects of hand dominance.

A study was performed to investigate the existence of any distinction in the fatiguability of corresponding contralateral muscles in the hand as a function of hand dominance. The first dorsal interosseous muscle was studied. The median frequency of the myoelectric signal was employed to describe the fatigue behavior of the muscle. It was found that during sustained contractions the median frequency decreased faster in the non-dominant hand of right handed individuals, whereas, no statistically significant distinction could be found in left handed individuals. This distinction was evident in both male and female subjects. This study demonstrates that continued preferential usage of a muscle is associated with altered electrical properties of the myoelectric signal and that the median frequency of the signal provides an appropriate measure of the modifications. It is argued that the findings may provide an indication of modifications in the metabolic properties of muscle fibers induced by a lifetime of preferred functional use.

Adult↗
PubMed1986

Effects of electrode location on myoelectric conduction velocity and median frequency estimates.

The effect of surface electrode location on the estimates of the median frequency and conduction velocity of the myoelectric signal was investigated. The locations were identified with respect to the innervation zone and the tendonous portion of the tibialis anterior muscle. Considerable modifications in the median frequency and conduction velocity parameters were noted. The highest values of the median frequency occurred at the region of the innervation zone and tendonous insertion of the muscle, and decreased proportionally with distance from these areas. The rate of change of median frequency was not effected by electrode location. Estimates of conduction velocity were most stable in a region between the distal tendon and the adjacent innervation zone. This region also provided the best linear fit when comparing conduction velocity to median frequency estimates. The implications for signal detection procedures are discussed.

Adult↗
PubMedDate not supplied

Dynamic evaluation of exercising leg muscle in healthy subjects with echo planar MR imaging: work rate and total work determine rate of T2 change.

Echo planar MR imaging of the leg was performed in nine healthy volunteers to better understand the dynamic relationship between exercise and changes in muscle T2. Imaging and T2 calculation was performed before, during, and after ankle dorsiflexion exercises using a TR of 9 seconds and a TE of 60 msec. Performing 9-second duty cycles, six of the subjects exercised for sets of 12 duty cycles, three with a graded series of weights and pulleys and three with an isometric orthotic device graded in varying percentages of maximum voluntary contraction. The other three volunteers performed duty cycles to fatigue. Gastrocnemius and soleus muscle T2 relaxation times were unchanged before, during, and after exercise. The tibialis anterior muscle showed an initial brief 1.7-6.2% decrease in T2 values after starting exercise, followed by a linear increase. Maximum T2 values and percent changes were higher for higher work rates (P < .05), and the rate of T2 change increased in a linear fashion with increasing work rates. By using rapid serial MR imaging, we show that the rate of muscle T2 change bears a simple linear relationship to muscle work. This technique may be exploited in both diagnostic and rehabilitation procedures.

Adult↗