Validity & Reliability of WIMU for measuring hamstring muscle extensibility

Hamstring extensibility is an important component of physical fitness and spinal health. In this context, extensibility is understood as the ability of muscle tissue to lengthen or stretch beyond the resting length. Short-hamstring syndrome is one of the main risk factors for athletic injuries, low back pain, etc.

The aims of the current study were to evaluate the validity of WIMU for measuring hamstring muscle extensibility in the passive straight leg raise (PSLR) test using an inclinometer for the criterion and determine the test-retest reliability of the WIMU to measure hamstring muscle extensibility during the PSLR test.

55 subjects were evaluated on 2 separate occasions. WIMU showed strong concurrent validity and excellent test-retest reliability for the evaluation of hamstring muscle extensibility in the PSLR test.

Infographics by José María Oliva

Validity & Reliability of a GPS device for quantifying athletes´ sprints and movement demands specific to team sports

The objective of this study was to study the validity and reliability of WIMU during 10m and 30m sprints, during team sports specific movements and the reliability during very high speeds (> 30 km/h).

GPS systems are commonly used to analysis football performance during either trainings or matches. While many studies have investigated the validity and reliability of these devices, there is a lack of objective procedures regarding synchronization with gold standards such as real distance or timing gates. This the first study that uses a high-speed video camera synchronized via software with a GPS device and timing gates to determine the sprint start point and sprint split. In conclusion, WIMU showed to be valid and reliable for measuring sprints at speed higher than 20 km/h as well as team sport movements

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Reliability & Validity of WIMU for measuring velocity during resistance exercises

First study to test the reliability and validity of WIMU enclosed to a Smith’s machine bar in order to measure velocity in back squat. This study had two main goals. The first was to determine the reliability of the WIMU for mean velocity measurements during resistance exercises at 40% and 80% 1 repetition maximum (maximum weight you can lift with maximum effort in a single repetition). The second was to compare the results for the WIMU to a linear encoder (gold standard) for mean velocity measurements when clipped to the bar during back squat exercises using the Smith machine.

23 trained men aged 22.3 ± 3.2 years participated in this study. At maximum velocity in the concentric phase, they performed 10 repetitions with 40% 1 repetition maximum and eight repetitions with 80% 1 repetition maximum while using the WIMU and T-Force linear encoder simultaneously to record data.

In conclusion, the findings of this study suggest that WIMU is a reliable and valid tool for the assessment of mean velocity during the back squat exercise using the Smith machine. These findings could help coaches and sport researchers evaluate athletes performing resistance exercises similar to squats with a reliable, valid and portable tool.

Infographics by José María Oliva

Trunk stability assesment using an inertial device (WIMU)

The purpose of this research was to perform a trunk strength assessment of protocols described in the literature using accelerometry, by means of CV and ApEn entropy calculations. In addition, to check differences in CV and ApEn variables depending on the type of exercise, as a secondary objective. Twenty-four male subjects who were part of a football team participating in the Third Division:

  •  Age: 23,4 ± 2,73 years
  • Height: 1,75 ± 0,09 cm
  • Weight: 74,3 ± 6,19 kg
  • -BMI (Body mass index): 21,51 ± 3,47 kg/m2)

This data was recorded by means of an inertial device located in the center of mass (L3) and their accelerometric signals were analyzed by two statistics: coefficient of variation (CV) and approximate entropy (ApEn).

Significant differences were found in the value of CV and ApEn in all exercises except between PP and PL in ApEn (p <0.05). The data were distributed in low, medium and high values of CV and ApEn of the participants. A trunk strength-stability assessment using an inertial device or multi-sensors is proposed as a practical method for strength and conditioning coaches. Also, the application of the statistics CV and ApEn for the analysis of signals in stability exercises is recommended.

infographics by José María Oliva