Resistance training is commonly used in sports for prevention of injuries and in rehabilitation. The purpose of this study was to compare closed versus open kinetic chain weight training of the thigh muscles and to determine which mode resulted in the greatest performance enhancement. Twenty-four healthy subjects were randomized into a barbell squat or a knee extension and hip adduction variable resistance weight machine group and performed maximal, progressive weight training twice a week for 6 weeks. All subjects were tested prior to training and at the completion of the training period. A barbell squat 3-repetition maximum, an isokinetic knee extension 1-repetition maximum, and a vertical jump test were used to monitor effects of training. Significant improvements were seen in both groups in the barbell squat 3-repetition maximum test. The closed kinetic chain group improved 23 kg (31%), which was significantly more than the 12 kg (13%) seen in the open kinetic chain group. In the vertical jump test, the closed kinetic chain group improved significantly, 5 cm (10%), while no significant changes were seen in the open kinetic chain group. A large increase of training load was observed in both subject groups; however, improvements in isotonic strength did not transfer to the isokinetic knee extension test. The results may be explained by neural adaptation, weight training mode, and specificity of tests.

J Orthop Sports Phys Ther. 1998;27(1):3-8.

Key Words: resistance training, free weights, weight machines, lower extremity

The etiology and nature of repetitive hamstring strain is complex and not fully understood. The purpose of this study was to investigate the presence of adverse neural tension in 14 male Rugby Union players with a history of grade I repetitive hamstring strain. Comparison was made to an injury-free matched control group. Adverse neural tension was assessed using the slump test. Hamstring flexibility was measured using the active knee extension in lying test. Results indicated that 57% of the test group had positive slump tests, suggesting the presence of adverse neural tension. None of the control group had a positive slump test. Analysis of variance revealed no differences in flexibility between groups or between those demonstrating a positive or negative slump test. Results suggest that adverse neural tension may result from or be a contributing factor in the etiology of repetitive hamstring strain. Residual decreased flexibility is not apparent in this subject group.

J Orthop Sports Phys Ther. 1998;27(1):16-21.

Key Words: neural tension, repetitive hamstring strain, slump test

Ultrasound is a commonly used therapeutic modality for which there is little research on the effect of treatment dosage on the extent of tissue heating. The purpose of this study was to investigate the effect of 2 different ultrasound devices, angle of ultrasound application, and treatment time on the temperature of a tissue phantom. Four trials were performed at 4 ultrasound application angles (90°, 80°, 70°, and 60°) with both an Excel UltraMax and a Mettler Sonicator 720. A continuous 1-MHz frequency at 2.0 W/cm2 was administered for 5 minutes, with tissue phantom temperature recorded at 1-minute intervals. The analysis of the data revealed significant main effects between ultrasound devices, angle of application, and treatment times. Interactions were identified between ultrasound device and treatment times and angle of application and treatment times. Analysis of simple effects revealed significant differences between ultrasound devices after 2, 3, 4, and 5 minutes of treatment and between treatment times and 80° and 60° angles of application. Maximal temperature increase after a 5-minute treatment was 2.025°C. This level of tissue heating falls below expected values and may not yield therapeutic results. The thermal effects were noted to be greatest at 80° and 90° angles of application. Despite appropriate calibration and identical treatment protocols, the 2 ultrasound devices yielded significantly different tissue phantom temperatures, which were notably lower than expected values. We concluded that direct monitoring of ultrasound device output and calculation of treatment dosage should occur on a routine basis, as treatment outcome will certainly be affected by the actual dosage of ultrasonic energy.

J Orthop Sports Phys Ther. 1998;27(1):27-31.

Key Words: ultrasound, therapeutic heating, tissue phantom

The sport of triathlon is a rapidly growing arena for athletic competition and training. Men and women of various fitness backgrounds have become involved in this sport that involves the disciplines of swimming, cycling, and running. Training for multiple sports has the advantages of providing the athlete with a variety of means of maintaining fitness in the event of an injury. On the other hand, multisport training may also contribute to a special category of injuries, those related to the cumulative effects of cross training. The purpose of this paper is to provide a review of the literature regarding triathlon training and injuries. A survey of a local triathlon club regarding the incidence of injuries is presented, and comparisons are made with previously published surveys. Finally, this paper attempts to outline the training conditions of the triathlete and to provide readers with strategies for injury management.

J Orthop Sports Phys Ther. 1998;27(1):42-50.

Key Words: triathlon, epidemiology, training