Validade e reprodutibilidade de receptores para o GPS em relação à distância percorrida / Validez y reproducibilidad de receptores GPS en relación de la distancia recorrida

Objetivo. El presente estudio evaluó la validez y reproducibilidad de dos modelos de receptores para el Global Positioning System (GPS). La validez fue evaluada comparando la distancia registrada por los receptores con la distancia conocida de estos trayectos. Método. Seis jóvenes tenistas (177,6 ± 6,2 cm; 76,6 ± 3,2 kg) recorrieron tres trayectos: 1) 100 m en la pista de atletismo (número de "disparos" = 120); 2) 400 m en la pista de atletismo (número de "disparos" = 60) y 3) 100 m con cambios de dirección (número de "disparos" = 120), utilizando los equipos Garmin© Forerunner 405 y Polar© RS800. Resultados. En los trayectos sin cambios de dirección (100 y 400 m), a través de la ANOVA two way (distancia y velocidad) no se detectaron diferencias entre la distancia conocida y las distancias registradas por los receptores analizados (p > 0,05). En el trayecto de 100 m con cambios de dirección, se observaron diferencias entre la distancia conocida y las registradas tanto por el Polar© RS800 como por el Garmin© Forerunner 405 (p < 0,05). También se verificó la diferencia en las distancias registradas por el Polar® RS800 y por el Garmin© Forerunner 405 para el trayecto realizado con cambios de dirección (p < 0,05). Conclusión. A través de los datos, se puede afirmar que los receptores para GPS evaluados presentaron un nivel aceptable de precisión para distancias recorridas sin cambios de dirección, sin embargo, la precisión de estos equipos en trayectos con cambios de dirección fue limitada (AU)

Objective. The present study evaluated the reproducibility and validity of two models of receivers for the Global Positioning System (GPS). Validity was assessed by comparing the distance recorded by the GPS receivers with the known distance. Method. Six young players (177.6 ± 6.2 cm; 76.6 ± 3.2 kg) performed three routes with different characteristics: 1) 100 m in the athletics track (number of "sprints" = 120); 2) 400 m in the athletics track (number of "sprints" = 60) and 3) 100 m with changes of direction (number of "sprints" = 120), using equipment Garmin© Forerunner 405 and Polar© RS800. Results. Regarding linear routes (100 and 400 m), no differences were detected using ANOVA two-way (distance and speed) between the known distance and distance recorded by GPS receivers analyzed (p > 0.05). Regarding non-linear route of, significant differences were observed between the known distance and recorded distance by the GPS receivers (p < 0.05). There was also a significant difference between the distance recorded by Polar© RS800 and Garmin© Forerunner 405 for the non-linear route (p < 0.05). Analysis of the limits of agreement reinforces the limitation of equipment in relation to accuracy for the non-linear route. Conclusion. These data suggest that the GPS receivers evaluated showed acceptable level of accuracy for linear routes, however, the accuracy of such devices on non-linear routes was limited (AU)

Monitoring training loads, stress, immune-endocrine responses and performance in tennis players.

The study aim was to investigate the effect of a periodised pre-season training plan on internal training load and subsequent stress tolerance, immune-endocrine responses and physical performance in tennis players. Well-trained young tennis players (n = 10) were monitored across the pre-season period, which was divided into 4 weeks of progressive overloading training and a 1-week tapering period. Weekly measures of internal training load, training monotony and stress tolerance (sources and symptoms of stress) were taken, along with salivary testosterone, cortisol and immunoglobulin A. One repetition maximum strength, running endurance, jump height and agility were assessed before and after training. The periodised training plan led to significant weekly changes in training loads (i.e. increasing in weeks 3 and 4, decreasing in week 5) and post-training improvements in strength, endurance and agility (P < 0.05). Cortisol concentration and the symptoms of stress also increased in weeks 3 and/or 4, before returning to baseline in week 5 (P < 0.05). Conversely, the testosterone to cortisol ratio decreased in weeks 3 and 4, before returning to baseline in week 5 (P < 0.05). In conclusion, the training plan evoked adaptive changes in stress tolerance and hormonal responses, which may have mediated the improvements in physical performance.

Is there a relationship between the total volume of load lifted in bench press exercise and the rating of perceived exertion?

AIM: The purpose of the study was to investigate the relationship between the total volume of load lifted (TVLL) and the rating of perceived exertion (RPE) measures during different resistance training (RT) schemes using the bench press exercise. METHODS: The present study was divided into two experiments. In the first experiment, 18 healthy men performed three different RT schemes: a strength oriented scheme (SS), a muscular endurance oriented scheme (ES) and a hypertrophy oriented scheme (HS). TVLL was calculated for each scheme. Mean-RPE and session-RPE were assessed. In the second experiment, 23 men performed two resistance exercise bouts at different intensities (50%-1RM and 75%-1RM) with matched TVLL. Mean-RPE and session-RPE were also assessed. RESULTS: SS and HS showed higher TVLL and greater RPE scores as compared to ES (P<0.05). No significant difference was observed between SS and HS. It was verified significant positive correlations between TVLL and session-RPE (SS r=0.63, HS r=0.64, ES r=0.56; P<0.05), and between mean-RPE and TVLL (SS r=0.55, HS r=0.52, ES r=0.47; P<0.05) for all schemes. No differences were observed for mean-RPE, session-RPE and TVLL between the 50%-1RM and 75%-1RM. Significant positive relationships between TVLL and session-RPE (50%-1RM r=0.61, 75%-1RM r=0.66; p<0.05) and between TVLL and mean-RPE (50%-1RM r=0.51, 75%-1RM r=0.49; P<0.05) were observed. CONCLUSION: The results of this study have shown that the TVLL in RT influences RPE measures. These findings corroborates the existence of a relationship between total work performed (external training load) and perception of effort (internal training load).