In this paper the design of a magnetic-field-to-voltage transducer based on the giant magnetoimpedance phenomenon (GMI) is proposed, characterized by an innovative geometric configuration. In order to attain the best near-field sensibility and far-field immunity, the transducer's sensitive element and electronic circuit were planned and implemented. By thoroughly characterizing them it was possible to obtain an estimate of the transducer's sensibility, which is approximately 12 V Oe −1 . This value is comparable to those observed in two of the most important existing magnetic sensors: the fluxgate and the Hall effect sensor. The main application of the developed transducer is the localization of magnetic foreign bodies in humans, based on a previously developed and tested SQUID sensor technique. In order to provide a better interpretation of the experimental results, a theoretical model of the magnetic field associated with a needle and of the signal it generates in the transducer was created. Measurements with a needle were performed to analyze the behavior of the prototype, which has a high sensitivity, as expected, but presents strong hysteresis, lack of linearity and low immunity to uniform fields. However, despite the improvements that can still be done and have already been identified, the developed transducer has many promising applications, and has the advantage of reduced fabrication and operation costs.

Background and Objectives: The aim of this study was twofold: (i) to analyze the relationships between fitness status (repeated-sprint ability (RSA), aerobic performance, vertical height jump, and hip adductor and abductor strength) and match running performance in adult women soccer players and (ii) to explain variations in standardized total distance, HSR, and sprinting distances based on players’ fitness status. Materials and Methods: The study followed a cohort design. Twenty-two Portuguese women soccer players competing at the first-league level were monitored for 22 weeks. These players were tested three times during the cohort period. The measured parameters included isometric strength (hip adductor and abductor), vertical jump (squat and countermovement jump), linear sprint (10 and 30 m), change-of-direction (COD), repeated sprints (6 × 35 m), and intermittent endurance (Yo-Yo intermittent recovery test level 1). Data were also collected for several match running performance indicators (total distance covered and distance at different speed zones, accelerations/decelerations, maximum sprinting speed, and number of sprints) in 10 matches during the cohort. Results: Maximal linear sprint bouts presented large to very large correlations with explosive match-play actions (accelerations, decelerations, and sprint occurrences; r = −0.80 to −0.61). In addition, jump modalities and COD ability significantly predicted, respectively, in-game high-intensity accelerations (r = 0.69 to 0.75; R2 = 25%) and decelerations (r = −0.78 to −0.50; R2 = 23–24%). Furthermore, COD had significant explanatory power related to match running performance variance regardless of whether the testing and match performance outcomes were computed a few or several days apart. Conclusion: The present investigation can help conditioning professionals working with senior women soccer players to prescribe effective fitness tests to improve their forecasts of locomotor performance.

Purpose. The study was intended to describe the correlations between speed performance (11 m, 22 m, and 33 m) and agility test in skates with determinants of muscular power (squat jump, countermovement jump) in young Portuguese roller hockey athletes involved in a regional selection. Methods. A cross-sectional study was conducted among 10 male roller hockey players with mean (± SD) age of 14.20 (0.57) years, involved in the Portuguese national competition of under-15, making part of the final Oporto district selection of players to participate in interregional selections competition. Their mean (± SD) weight, height, body mass index, and sum of the skinfolds were 58.62 (8.78) kg, 165.72 (8.45) cm, 21.26 (1.52) kg/m 2 , 51.80 (14.91) mm, respectively. Furthermore, it strength was measured with squat jump and countermovement jump; sprinting time at 11 m, 22 m, and 33 m was determined, as well as time in an agility t-test, conducted in roller skating. Spearman correlation coefficients were calculated to test the associations. Results. Significant inverse correlations between vertical jumps, a practical method of power training monitoring, and linear velocity in skating (countermovement jump vs. speed,-0.78) were found. Despite the increasing complexity of the agility test, a moderate inverse correlation with strength was observed, too (-0.48). Conclusions. Lower limbs explosive strength turned out a strong predictor of skating linear speed and agility among young roller hockey players, providing a simple evaluation tool of important determinants of performance.

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