Concurrent Validity and Reliability of a Low-Cost Dynamometer to Assess Maximal Isometric Strength in Neck Movements

OBJECTIVE

This study aimed to evaluate the concurrent validity and reliability of a low-cost digital dynamometer to assess maximal isometric strength in neck movements.

METHODS

Twelve recreationally active participants (6 women, 6 men; age: 24.1 ± 3.4 years; height: 1.71 ± 0.06 m; weight: 64.6 ± 11.7 kg) performed neck flexion, extension, and lateral flexion, and maximal isometric strength was simultaneously measured using an isokinetic dynamometer (gold standard) and a digital dynamometer to evaluate the concurrent validity of the latter. One week later, all the participants repeated 3 trials of each neck movement (3 minutes apart) registered only with the digital dynamometer. The first and second trial were guided by tester 1 and the third trial was guided by tester 2.

RESULTS

The concurrent validity of the digital dynamometer showed a nearly perfect correlation between both devices (r > 0.986, P < .001), with Bland-Altman plots showing absolute agreement. Intertester and intratester reliability were nearly perfect for all neck movements (intraclass correlation coefficient > 0.86).

CONCLUSION

The low-cost digital dynamometer showed valid and reliable measurements of maximal isometric strength in neck movements.

A New Method to Segment the Multiple Sclerosis Lesions on Brain Magnetic Resonance Images

Automatic segmentation of multiple sclerosis (MS) lesions in brain magnetic resonance imaging (MRI) has been widely investigated in the recent years with the goal of helping MS diagnosis and patient follow-up. In this research work, Gaussian mixture model (GMM) has been used to segment the MS lesions in MRIs, including T1-weighted (T1-w), T2-w, and T2-fluid attenuation inversion recovery. Usually, GMM is optimized by using expectation-maximization (EM) algorithm. The drawbacks of this optimization method are, it does not converge to optimal maximum or minimum and furthermore, there are some voxels, which do not fit the GMM model and have to be rejected. So, GMM is time-consuming and not too much efficient. To overcome these limitations, in this research study, at the first step, GMM was applied to segment only T1-w images by using 100 various starting points when the maximum number of iterations was considered to be 50. Then segmentation results were used to calculate the parameters of the other two images. Furthermore, FAST-trimmed likelihood estimator algorithm was applied to determine which voxels should be rejected. The output result of the segmentation was classified in three classes; White and Gray matters, cerebrospinal fluid, and some rejected voxels which prone to be MS. In the next phase, MS lesions were detected by using some heuristic rules. This new method was applied on the brain MRIs of 25 patients from two hospitals. The automatic segmentation outputs were scored by two specialists and the results show that our method has the capability to segment the MS lesions with dice similarity coefficient score of 0.82. The results showed a better performance for the proposed approach, in comparison to those of previous works with less time-consuming.

ARE THERE DIFFERENCES IN STRENGTH TESTS USING ISOKINETIC DYNAMOMETRY BETWEEN FIELD AND INDOOR PROFESSIONAL SOCCER PLAYERS?

OBJECTIVE

The objective of this study was to conduct a comparative analysis on isokinetic strength assessments between field and indoor male professional soccer players and correlate the findings with the higher levels of injury risk described in the literature.

METHODS

We analyzed 16 field soccer players and 15 indoor soccer players. All these professionals were male. Isokinetic muscle strength assessments were made on their knees.

RESULTS

The mean weight was 81.81 kg for field soccer and 80.33 kg for indoor soccer. The right and left peak extensor torque left and right for field soccer and indoor soccer were, respectively, 302.50 and 313.31 Nm and 265.20 and 279.80 Nm, and for flexors, 178 and 184.88 Nm and 158.27 and 154 Nm. The peak torque rates according to body weight for the left and right extensors for field soccer and indoor soccer were, respectively, 3.84 and 3.7 Nm/kg and 3.32 and 3.52 Nm/kg, and for flexors, 2.17 and 2.26 Nm/kg and 1.98 and 1.93 Nm/kg. The balance relationships between flexors and extensors on the right and left sides for field soccer and indoor soccer were, respectively, 59.81 and 59.44% and 60.47% and 54.80%. The relationships for extensors between the right and left sides for field soccer and indoor soccer were, respectively, 11.44 and 9.20%, and for the flexors, 7.31 and 8.80%.

CONCLUSIONS

In accordance with international parameters, comparative analysis on isokinetic strength assessments between field and indoor male professional soccer players before the season showed that there was muscle balance and low probability of injury. There were no statistically significant differences in the parameters analyzed between the players of the two types of soccer.