Effects of short-term isokinetic training on standing long-jump performance in untrained men.

The purpose of this study was to examine the effects of a 6-week isokinetic training program on quadriceps and hamstrings peak torque (PT) and standing long-jump (SLJ) performance. Twelve untrained men (age 31.4 +/- 4.2 years, mean +/- SD) were tested at a velocity of 1.75 rad.s(-1) (100 degrees.s(-1)), before and after a 6-week control period and on completion of a 6-week training program. Training consisted of 3 sets of 10 repetitions, 3 days per week, for 6 weeks. Repeated-measures analysis-of-variance analyses revealed that quadriceps PT increased, on average, by 10.5% as a result of training (p < 0.01). No significant changes in hamstrings PT (p = 0.062) and SLJ performance occurred as a result of training (p > 0.05). The major finding of this study was that PT gains subsequent to isokinetic resistance training did not influence functional performance. That open-chain training did not affect the performance of a closed-chain activity is unsurprising, but on these grounds of nonfunctionality, the use of moderate velocity isokinetic dynamometry in rehabilitation and performance assessment for closed-chain sports needs addressing in future research.

Prediction of posterior fossa tumor type in children by means of magnetic resonance image properties, spectroscopy, and neural networks.

Recent studies have explored characteristics of brain tumors by means of magnetic resonance spectroscopy (MRS) to increase diagnostic accuracy and improve understanding of tumor biology. In this study, a computer-based neural network was developed to combine MRS data (ratios of N-acetyl-aspartate, choline, and creatine) with 10 characteristics of tumor tissue obtained from magnetic resonance (MR) studies, as well as tumor size and the patient's age and sex, in hopes of further improving diagnostic accuracy. Data were obtained in 33 children presenting with posterior fossa tumors. The cases were analyzed by a neuroradiologist, who then predicted the tumor type from among three categories (primitive neuroectodermal tumor, astrocytoma, or ependymoma/other) based only on the data obtained via MR imaging. These predictions were compared with those made by neural networks that had analyzed different combinations of the data. The neuroradiologist correctly predicted the tumor type in 73% of the cases, whereas four neural networks using different datasets as inputs were 58 to 95% correct. The neural network that used only the three spectroscopy ratios had the least predictive ability. With the addition of data including MR imaging characteristics, age, sex, and tumor size, the network's accuracy improved to 72%, consistent with the predictions of the neuroradiologist who was using the same information. Use of only the analog data (leaving out information obtained from MR imaging), resulted in 88% accuracy. A network that used all of the data was able to identify 95% of the tumors correctly. It is concluded that a neural network provided with imaging data, spectroscopic data, and a limited amount of clinical information can predict pediatric posterior fossa tumor type with remarkable accuracy.

Biomechanical factors critical for performance in the men's javelin throw.

In the men's javelin event the athlete throws an 800g implement into a 40 degrees sector. The objective is to throw as far as possible. Compared with most other throwing implements, the javelin is relatively aerodynamic. Even so, the most important release parameter is still the release speed. Maximising this parameter gives the athlete the best chance of attaining success in the event. For an elite thrower, as much as 70% of the release speed of the javelin is developed in the last 0.1 second. As such, the movements of throwers during this period and immediately preceding it have received attention from researchers. It would appear that a thrower's body position at the instant of final foot strike, his ability to transfer momentum between the lower body and the upper body during the delivery, and coordination of the working body segments in the most effective manner are linked to his success in the event. This paper reviews the most important biomechanical research on the men's javelin throw and highlights findings such as these which may improve the understanding of how elite javelin throwers achieve success.

A three-dimensional analysis of javelin throwing technique.

This paper reports a three-dimensional kinematic analysis of the best throws from the women's and men's javelin competitions at the 1991 World Student Games in Sheffield. This was undertaken to obtain accurate three-dimensional release parameter values for elite javelin throwers in a top competition, to relate the release parameters to important temporal and kinematic features of the javelin throwing technique and to carry out an assessment of the adequacy of two-dimensional estimates of release parameter values in comparison with those from the three-dimensional analysis. Cine-film was taken using two phase-locked Panasonic 1PL cameras running at a frame rate of 100 Hz, and every other frame was digitized. All methodologies were in accord with the guidelines of the British Association of Sports Sciences. The results indicated the possibility of two different throwing techniques, within and between individuals, relating both to the timing of hip joint actions within the kinematic chain and the trade-off between the impulse applied to the javelin and run-up speed. The results also indicated that important release parameter values assessed from the xz-plane alone differed only marginally from those from three dimensions. The extra information obtainable from three-dimensional analysis (such as angle of sideslip, incidence magnitude, azimuth angle, angle of track and yaw rate) along with the poor representation of the time-course of important variables obtained from the xz-plane makes the three-dimensional analysis of this event essential. This is further strengthened by the practical use of three-dimensional analysis in allowing coaches and throwers the opportunity to view the event from any perspective. Recommendations for future research include further three-dimensional kinematic analyses with priority being given to assessing ways of estimating wind conditions around the javelin runway and of incorporating the vibrations of the javelin within the analysis.

The impact of a clinic for adults with HIV infection on the microbiology laboratory.

The Infectious Diseases Clinic (IDC) discussed serves adults who are seropositive for human immunodeficiency virus. The authors reviewed the outpatient and inpatient microbiology tests of a three-month period during 1989 for a systematic sample of IDC patients. The 249 patients in the sample had 682 microbiology tests performed during the period (mean 2.7 tests per patient). Tests most frequently requested were mycobacterial culture, routine blood culture, and cryptococcal antigen determination. Patients with acquired immunodeficiency syndrome (43% of IDC patients) accounted for 63% of the requested IDC tests. IDC patients comprised about 2.4% of patients served but accounted for 3.9% of the requested microbiology tests and 6.6% of the microbiology work load for reported tests. Using Centers for Disease Control case projections, the authors estimated that services to IDC patients in 1993 would comprise 6.6% of all microbiology tests and 10.6% of the microbiology work load. The implications of these data for microbiology probably also apply to other laboratory testing and emphasize the need for more efficient ways to use and perform diagnostic studies required by patients with HIV infection.

Medicare fraud and abuse: implications for physicians.

Since the inception of the Prospective Payment System, the physician fee freeze, and other cost-cutting measures, physicians have been approached with many income-generating opportunities relating to their practices. Unfortunately, many of these opportunities also present potential criminal and civil liability under federal Medicare anti-fraud and abuse provisions. The recent passage of the Medicare and Medicaid Program Patient Protection Act of 1987 has updated federal anti-fraud and abuse laws and expanded the sanctions which may be imposed on physicians. This article describes the types of activities prohibited by federal laws and discusses the operation of these laws in light of common joint venture, incentive, and contract arrangements frequently seen in medical practice.