Effects of electrical and electromagnetic stimulation after anterior cruciate ligament reconstruction.

A need exists to develop new methods of neuromuscular electrical stimulation (NMES) that are both effective and relatively pain-free. The purpose of this pilot study was to determine the effects of both NMES and a new method of electromagnetic (NMES/PEMF) stimulation for reducing girth loss and for reducing pain and muscle weakness of the knee extensor muscles in patients during the first 6 weeks after reconstructive surgery of the anterior cruciate ligament (ACL). Seventeen patients receiving ACL reconstructive surgery participated as a control group (N = 3), as an NMES group (N = 7), and with combined NMES and magnetic field stimulation (NMES/PEMF) (N = 7). Patients receiving NMES/PEMF rated each type of stimulation for perceived pain and were measured for their torque. Torque results revealed a mean decrease of 13.1% for NMES/PEMF patients. The mean percent of thigh girth decreased 8.3% for controls, 0.5% for NMES, and 2.3% for NMES/PEMF patients. The NMES/PEMF patients rated NMES as causing about twice the pain intensity as NMES/PEMF during treatments. As a result of this data, the authors conclude that both NMES and NMES/PEMF are effective in reducing girth loss and that NMES/PEMF is less painful than NMES alone in treating patients after ACL reconstruction.

Effect of variation in the burst and carrier frequency modes of neuromuscular electrical stimulation on pain perception of healthy subjects.

The purpose of this study was to explore the effect of various combinations of burst and carrier frequencies of neuromuscular electrical stimulation (NMES) on subjects' perception of pain intensity associated with induction of high intensity muscle contractions. Twenty-seven healthy volunteers completed the study. After the initial test session, all subjects were treated in three additional sessions with nine combinations of burst frequencies (50, 70, and 90 bursts per second [bps]) and carrier frequencies (2,500, 5,000, and 10,000 Hz) at an NMES amplitude that produced torque equivalent to 50% of maximal voluntary contraction of their quadriceps femoris muscle. Subjects rated each frequency combination for perceived pain intensity with a visual analog scale. The combinations of burst frequencies (50, 70, and 90 bps) and carrier frequencies (2,500 and 5,000 Hz) do not differ from each other in perceived pain intensity but do differ significantly in perceived pain from the combinations of burst frequencies at the carrier frequency of 10,000 Hz. Thus, the clinician may have to try different stimulus combinations on patients at different current training levels to obtain the least individually perceived pain.

Kinematics, ground reaction force, and muscle balance produced by backward running.

This study was conducted at the University of Kentucky Biodynamics Laboratory in Lexington, KY and was partially supported by a grant from the Kentucky Chapter of the American Physical Therapy Association. Backward running (BR) is employed for conditioning and for rehabilitation in sports, orthopaedics, and neurology. Our purposes were to compare kinematics and training effects of BR to forward running (FR). Ten runners (6 males, 4 females, ages 20-34 years) were assigned to a backward running (BRG) or control (FRG) group. Subject isokinetic muscular torque production (IMTP) and biomechanics during FR and BR at 3.58 m/sec were studied at the beginning and after 8 weeks of training. Stance time was significantly shorter during BR. The peak vertical component of the ground reaction force (Fz) and Fz impulse were significantly less during BR. After training, knee extensor IMTP of the BRG increased significantly at 75 and 120 degrees /sec. We concluded that BR produced lower Fz stress than FR and improved knee extensor torque at low speeds. Backward running may be clinically useful for reducing stress to injured joints and for increasing knee extensor strength. J Orthop Sports Phys Ther 1989;11(2):56-63.