Validity and Reliability of a Load Cell Sensor-Based Device for Assessment of the Isometric Mid-Thigh Pull Test.

In recent years, there has been an exponential increase in the number of devices developed to measure or estimate physical exercise. However, before these devices can be used in a practical and research environment, it is necessary to determine their validity and reliability. The purpose of this study is to test the validity and reliability of a load cell sensor-based device (LC) for measuring the peak force (PFr) and the rate of force development (RFD) during the isometric mid-thigh pull (IMTP) test, using a force plate (FP) as the gold standard. Forty-two undergraduate sport science students (male and female) participated in this study. In a single session, they performed three repetitions of the IMTP test, being tested simultaneously with an LC device and a Kistler force platform (FP). The PFr and RFD data were obtained from the force-time curve of the FP and compared with the LC data, provided automatically by the software of the device (Smart Traction device©). The mean difference between the results obtained by the LC device and the gold-standard equipment (FP) was not significantly different (p > 0.05), for both PFr and RFD, which suggests the validity of the ST results. Bland-Altman analysis showed a small mean difference in PFr = 1.69 N, upper bound = 47.88 N, and lower bound = -51.27 N. RFD showed that the mean difference was -5.27 N/s, upper limit = 44.36 N/s, and lower limit = -54.91 N/s. Our results suggest that the LC device can be used in the assessment of the isometric-mid-thigh-pull test as a valid and reliable tool. It is recommended that this device's users consider these research results before putting the ST into clinical practice.

Magnitude and Shape of the Forces Applied on the Foot Rest and Paddle by Elite Kayakers.

The study aimed to investigate the magnitude and shape of the forces applied on the foot rest, foot strap, and paddle. Thirteen elite male kayakers participated in this study and performed a 2-min test simulating 500 m race pace in a kayak ergometer. Forces applied by the kayakers on the paddle, foot rest, and foot strap were measured with load cells and recorded by an electronic measuring system. The magnitude of the peak forces applied on the foot rest (left: 543.27 ± 85.93; right: 524.39 ± 88.36) approximately doubled the ones applied on the paddle (left: 236.37 ± 19.32; right: 243.92 ± 28.89). The forces on the foot strap were similar in magnitude to the paddle forces (left: 240.09 ± 74.92; right: 231.05 ± 52.01). A positive correlation was found between the peak forces applied on the foot rest and paddle on the same side (p < 0.001). When comparing the best and worst kayakers' performance, the best showed greater forces magnitudes and synchronization of the peak forces. Analyses of the force-time curves, including not only the forces applied by the kayaker on the paddle but also the ones applied on the foot rest and strap, should be considered relevant in terms of technique analyses.

Validation of a global positioning system with accelerometer for canoe/kayak sprint kinematic analysis.

This study aimed to validate the use of a Global Positioning System with an accelerometer (GPS-Acc) unit to quantify canoeing kinematic variables. Eight canoe and kayak (200 and 500 m) sprint races were analysed. All the races were recorded sideways by a digital camera that followed the kayak or canoe bow and simultaneously using a GPS-Acc unit recorded the data concerning boat position, velocity, and acceleration. In 200 m races, 50 m splits were established over the entire race distance. In 500 m races, 100 m splits were used, excepting the race start and end, where the splits were divided into two sections of 50 m. The data of the GPS-Acc unit were analysed using a self-developed routine. The agreement between the video and the GPS-Acc analysis was measured regarding all the variables by a Bland-Altman analysis. No differences were found between both methodologies, except for time and velocity at the first 50 m, suggesting thus an agreement between the analysis methods. The GPS-Acc unit is valid for measuring quickly and accurately kinematic variables, mainly boat velocity and stroke rate. However, video analyses may be necessary when a more detailed analysis of the paddling technique is of interest.

The Importance of Biological Maturation and Years of Practice in Kayaking Performance.

Previous canoe sprint studies evaluated the best paddlers of their categories. This investigation aimed to identify the importance of biological maturation and athletes' experience in kayaking performance and observe possible differences regarding anthropometry, years of practice, and performance. Eighty under 14 years of age (U14) and fifty under 16 years of age (U16) kayakers aged 13.40 ± 0.54 and 15.25 ± 0.61 years were evaluated. Kayakers were assessed for anthropometry (body mass (kg); stretch stature (cm); and sitting height (cm)), performance (time at 3000 m for U14 and 5000 m for U16 kayakers), and somatic maturation (predicted adult height (PAH) and maturity offset). In the U14 kayakers, years of practice, sitting height, and maturity offset showed significant differences (p < 0.05) between the Top10 and Middle, and Middle and Bottom10 performance times. Significantly higher (p < 0.05) sitting heights were identified between the Top10 and Middle U16 kayakers. Significant differences (p < 0.05) were observed for maturity offset and PAH% between the Top10 and Middle groups compared to the Bottom10 group. In conclusion, this research shows differences in the maturity status of young U14 and U16 kayakers, identifying that the more biologically mature individuals, with more years of specific practice, achieved better performances.

Effect of 16-week blood flow restriction exercise on functional fitness in sarcopenic women: a randomized controlled trial / Efecto del ejercicio de restricción del flujo sanguíneo de 16 semanas sobre la aptitud funcional en mujeres sarcopénicas: un ensayo controlado aleatorio

SUMMARY: We investigated the effect of the intervention using the BFR method on functional capacity after 16 weeks in elderly women. In a controlled clinical trial, 23 women were randomly allocated into two groups, low-intensity exercise with blood flow restriction (LI + BFR, N = 11, Age: 69.40 ± 5.73) and control group (CG, N = 12, Age: 69.00 ± 6.39). The LI + BFR group had a volume of 75 repetitions at 20-30 % of 1RM and 3-4 sets per exercise (30, 15, 15 and repetitions with 30" rest between sets). The CG did not undergo any type of exercise. Functional capacity, anthropometry and sarcopenia were verified through a battery of tests before and after 16 weeks. The LI + BFR group had significant improvement in performance in Handgrip strength, Chair Stand, Arm curl, 2.44 Up-and-Go and 6 min walk, Sit-andreach and Back Scratch (p<0.05) after the intervention. The elderly women were still classified as sarcopenic, despite the improvement in the Muscle Mass Index (p<0.01). CG did not present significant changes. The BFR method can be an effective in the intervention process using physical exercise as an auxiliary strategy in the control of sarcopenia, providing a physical profile during the aging process.

RESUMEN: Investigamos en mujeres ancianas el efecto de la intervención utilizando el método de restricción del flujo sanguíneo en la capacidad funcional, después de 16 semanas. En un ensayo clínico controlado, 23 mujeres fueron asignadas aleatoriamente en dos grupos; ejercicio de baja intensidad con restricción de flujo sanguíneo (BI + RFS, N = 11, edad: 69,40 ± 5,73) y grupo control (GC, N = 12, Edad: 69,00 ± 6,39). El grupo BI + RFS tuvo un volumen de 75 repeticiones al 20-30 % de 1RM y 3-4 series por ejercicio (30, 15, 15 y repeticiones con 30 " de descanso entre series). El GC no fue sometido a ningún tipo de ejercicio. La capacidad funcional, la antropometría y la sarcopenia se verificaron mediante una batería de pruebas antes y después de 16 semanas. El grupo BI + RFS tuvo una mejora significativa en el rendimiento de la fuerza de la empuñadura, soporte de la silla, curvatura del brazo, 2,44 up-and-go y 6 min, 'sit-and-reach' 'Back Scratch' (p<0,05) después de la intervención. Las mujeres de edad avanzada seguían clasificadas como sarcopénicas, a pesar de la mejora en el índice de masa muscular (p<0,01). El GC no presentó cambios significativos. El método de restricción del flujo sanguíneo puede ser efectivo en el proceso de intervención utilizando ejercicio físico como estrategia auxiliar en el control de la sarcopenia, proporcionando un perfil físico durante el proceso de envejecimiento.

Effect of 16 weeks of resistance exercise and detraining comparing two methods of blood flow restriction in muscle strength of healthy older women: A randomized controlled trial.

OBJECTIVE: The objective of this study was to compare the effect of 16 weeks of resistance training using different occlusion pressures, followed by 6 weeks of detraining on the muscular strength levels of older women. METHODS: This randomized-controlled trial included 56 recreationally active women (68.8 ±â€¯5.09 years), randomized into 5 groups: 1) Low-intensity with blood flow restriction "High" (LI + BFR_H): with higher occlusion pressure, 2) Low-intensity with blood flow restriction "Low" (LI + BFR_L): with lower occlusion pressure, 3) High-intensity (HI), 4) Low-intensity (LI), and 5) Control Group (CG). Participants completed 16 weeks of resistance exercise training, followed by a 6-week detraining period. Maximal isokinetic torque (N.m) of right and left knee extension (PTRE/PTLE) and flexion (PTRF/PTLF) was measured at pre-training, post-training and immediately following the detraining period. RESULTS: Increased strength was observed in the LI + BFR_H, LI + BRF_L and HI groups post-training compared to baseline in the PTRE (Δ% = 27.2, 15.75 and 13.81%, p < .05, respectively), PTLE (Δ% = 25.2, 18.95 and 30.39%, p < .05, respectively), PTRF (Δ% = 36.7, 22.79 and 34.97%, p < .05, respectively) and PTLF in the groups (Δ% = 35.8, 24.93 and 26.14%, p < .05, respectively). Following the detraining period, the LI + BFR_H, LI + BFR_L and HI groups had a decrease in strength levels, but values did not decrease below baseline level. CONCLUSION: Low intensity BFR resistance exercise increases muscle strength in older women similar to HI, with higher occlusion pressures being more effective. Muscle strength was well preserved following a 6-week detraining period, and although reductions were observed, some preservation of strength can be explained by possible neural adaptations to exercise.