Reliability of a handball specific strength test battery and the association with sprint and throwing performance in young handball players

BACKGROUND

A greater motivation for coaches to be more involved in assessment could be the development of specific strength tests closer to specific handball tasks. Therefore, the aims were to determine the reliability of a handball specific strength test battery in young handball players using a functional electromechanical dynamometer (FEMD) and to evaluate the association between the strength test battery and performance measurements.

METHODS

Thirty-two young handball players (25% males and 75% females) performed a repeated-measurement design over four weeks. The players conducted one session per week, with each measurement consisting of two isometric tests to obtain isometric peak force, and four incremental tests. Moreover, performance handball tests (sprint and throwing velocity [TV]) were recorded.

RESULTS

The reliability of the whole handball specific strength tests was very high for the peak and mean strength (ICC=0.70-0.85; CV=8.49-13.99; SEM=0.44-0.67 kg). The step forward had a moderate association with 5 to 10 meters' time. The highest correlation between TVmean was found with the peak strength of standing lift and between TVpeak with peak strength of unilateral throw. The sprint total time could be explained by Body Mass Index and peak strength of the standing lift in the 40% and the TVpeak could be explained by arm span and mean strength of the standing lift in the 68%.

CONCLUSIONS

The high reliability for all exercises and the significant correlation with handball performance (sprint time and TV) allow us to include these tests in handball team evaluation and training.

Influence of trunk rotator strength on rotational medicine ball throwing performance

BACKGROUND

The strength of the trunk musculature plays an essential role in performance. The aims of this study were to analyze the relationship between the strength of the trunk rotation muscles with rotational medicine ball throwing velocity and distance, to study differences between sex in rotational medicine ball throwing and to compare the asymmetries of trunk rotational strength and rotational medicine ball throwing.

METHODS

Thirty physically active college students participated on the study. Horizontal and low cable woodchop exercises were assessed with a functional electromechanical dynamometer and throwing was measured with a radar and a measuring tape. A Pearson's correlation coefficient was calculated for the relation between trunk rotational strength and rotational medicine ball throwing. Independent samples t-test was performed to determine the differences between sex in rotational medicine ball throwing and a paired samples t-test was performed to study the asymmetries.

RESULTS

Large and very large correlations were obtained between trunk rotational strength and rotational medicine ball throwing (r=0.68-0.79). Significant differences and a large effect size were found between males and females for all throwing velocity and throwing distance variables (P<0.05; ES>0.90) and asymmetries in performance of mean velocity throwing (P=0.003; ES=-0.60) and peak velocity throwing (P=0.025; ES=-0.43). No significant differences were found between dominant and non-dominant side in any of the trunk rotator strength assessment conditions (P>0.05).

CONCLUSIONS

There is a large or very large correlation between the STRM and the RMBT in all its modalities. Differences in strength were found between sexes, with no significant differences between dominant and non-dominant sides.

Test-Retest Reliability of 3 Specific Strength Tests in Professional Handball Players

CONTEXT

Current devices to assess strength performance in handball may not be sufficiently sports-specific and reliable methods. Functional electromechanical dynamometry is a new technology that allows the development of accurate strength tests in athletes.

PURPOSE

To determine the absolute and relative reliability and to compare the reliability of the right and left side, and mean and peak force of 3 specific strength tests in handball players with a functional electromechanical dynamometer: unilateral pullover, standing lift, and step forward.

METHODS

Fourteen male handball players of the first Spanish division (28.79 [4.81] y; 10.38 [4.63] y of professional experience) performed a repeated-measurement design. Three testing sessions were performed (one per week). The first measurement consisted of 4 isometric tests (right and left unilateral pullover, and right and left standing lift) to obtain isometric peak force, and in the second and third sessions, 6 incremental tests until failure (right and left unilateral pullover, and right and left standing lift, right and left step forward) were performed.

RESULTS

The tests provided high reliability or acceptable reliability for mean and peak strength of unilateral pullover, standing lift and step forward (intraclass correlation coefficient = .83-.97; coefficient of variation = 3.90-11.57). Effect side was negligible in any of the parameters, except for a small effect side in the left peak force for unilateral pullover and a small effect side on the left side for a step forward. Significant differences in reliability (coefficient of variation ratio > 1.15) were found between the right and left sides and peak and mean force in all exercises except peak force in unilateral pullover and step forward.

CONCLUSION

These results confirm that the tests could be applied to assess physical performance in handball at the same time as regular gym training. Moreover, this is an excellent opportunity to individualize the player's weekly load.

Isokinetic Trunk Strength in Acute Low Back Pain Patients Compared to Healthy Subjects: A Systematic Review

BACKGROUND

The purpose of this systematic review was to: (I) determine the quality of evidence from studies assessing trunk isokinetic strength in subjects with acute low back pain (ALBP) compared to healthy subjects and (II) establish reference values of isokinetic trunk strength in subjects with ALBP.

METHODOLOGY

Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) statements were followed using keywords associated with trunk, strength and low back pain. Four databases were used: PubMed, Web of Science, Scopus and SPORTDiscus. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS).

RESULTS

A total of 1604 articles were retrieved, four included in this review. All were evaluated as high risk of bias (Rob). Due to the high Rob and the diversity of protocols, instruments and variables used, it was not possible to determine reference values for subjects with ALBP, we can only establish a range of flexion peak torque (PT) between 175.1 and 89.7 Nm at 60°/s and between 185 and 81.5 Nm at 120°/s, and for extension PT between 240.0 and 91.5 Nm at 60°/s and between 217.5 and 69.2 Nm at 120°/s in subjects with ALBP.

CONCLUSIONS

Due to the low quality of the evidence and the diversity of protocols used when measuring trunk isokinetic strength, it is necessary to carry out new high-quality research to establish reference values of trunk strength in subjects with ALBP.

Reliability of a standing isokinetic shoulder rotators strength test using a functional electromechanical dynamometer: effects of velocity

Background

The evaluation of the force in internal rotation (IR) and external rotation (ER) of the shoulder is commonly used to diagnose possible pathologies or disorders in the glenohumeral joint and to assess patient’s status and progression over time. Currently, there is new technology of multiple joint isokinetic dynamometry that allows to evaluate the strength in the human being. The main purpose of this study was to determine the absolute and relative reliability of concentric and eccentric internal and external shoulder rotators with a functional electromechanical dynamometer (FEMD).

Methods

Thirty-two male individuals (21.46 ±  2.1 years) were examined of concentric and eccentric strength of shoulder internal and external rotation with a FEMD at velocities of 0.3 m s⁻¹ and 0.6 m s⁻¹. Relative reliability was determined by intraclass correlation coefficients (ICC). Absolute reliability was quantified by standard error of measurement (SEM) and coefficient of variation (CV). Systematic differences across velocities testing circumstances, were analyzed with dependent t tests or repeated-measures analysis of variance in case of 2 or more than 2 conditions, respectively.

Results

Reliability was high to excellent for IR and ER on concentric and eccentric strength measurements, regardless of velocity used (ICC: 0.81–0.98, CV: 5.12–8.27% SEM: 4.06–15.04N). Concentric outcomes were more reliable than eccentric due to the possible familiarization of the population with the different stimuli.

Conclusion

All procedures examined showed high to excellent reliability for clinical use. However, a velocity of 0.60 m s⁻¹ should be recommended for asymptomatic male patients because it demands less time for evaluation and patients find it more comfortable.

Reliability of isometric and isokinetic trunk flexor strength using a functional electromechanical dynamometer

Aim

To determine the absolute and relative reliability of functional trunk tests, using a functional electromechanical dynamometer to evaluate the isokinetic strength of trunk flexors and to determine the most reliable assessment condition, in order to compare the absolute and relative reliability of mean force and peak force of trunk flexors and to determine which isokinetic condition of evaluation is best related to the maximum isometric.

Methods

Test-retest of thirty-seven physically active male student volunteers who performed the different protocols, isometric contraction and the combination of three velocities (V₁ = 015 m s⁻¹ , V₂ = 0.30 m  s⁻¹, V₃ = 0.45 m s⁻¹) and two range of movement (R₁ = 25% cm ; R₂ = 50% cm) protocols.

Results

All protocols to evaluate trunk flexors showed an absolute reliability provided a stable repeatability for isometric and dynamic protocols with a coefficient of variation (CV) being below 10% and a high or very high relative reliability (0.69 < intraclass correlation coefficient [ICC] > 0.86). The more reliable strength manifestation (CV = 6.82%) to evaluate the concentric contraction of trunk flexors was mean force, with 0.15 m  s⁻¹ and short range of movement (V₁R₁) condition. The most reliable strength manifestation to evaluate the eccentric contraction of trunk flexors was peak force, with 0.15 m  s⁻¹ and a large range of movement (V₁R_2; CV = 5.07%), and the most reliable way to evaluate isometric trunk flexors was by peak force (CV = 7.72%). The mean force of eccentric trunk flexor strength with 0.45 m  s⁻¹ and short range of movement (V₃R₁) condition (r = 0.73) was best related to the maximum isometric contraction.

Conclusion

Functional electromechanical dynamometry is a reliable evaluation system for assessment of trunk flexor strength.

Reliability and validity of different methods of estimating the one-repetition maximum during the free-weight prone bench pull exercise

This study examined the reliability and validity of three methods of estimating the one-repetition maximum (1RM) during the free-weight prone bench pull exercise. Twenty-six men (22 rowers and four weightlifters) performed an incremental loading test until reaching their 1RM, followed by a set of repetitions-to-failure. Eighteen participants were re-tested to conduct the reliability analysis. The 1RM was estimated through the lifts-to-failure equations proposed by Lombardi and O'Connor, general load-velocity (L-V) relationships proposed by Sánchez-Medina and Loturco and the individual L-V relationships modelled using four (multiple-point method) or only two loads (two-point method). The direct method provided the highest reliability (coefficient of variation [CV] = 2.45% and intraclass correlation coefficient [ICC] = 0.97), followed by the Lombardi's equation (CV = 3.44% and ICC = 0.94), and no meaningful differences were observed between the remaining methods (CV range = 4.95-6.89% and ICC range = 0.81-0.91). The lifts-to-failure equations overestimated the 1RM (3.43-4.08%), the general L-V relationship proposed by Sánchez-Medina underestimated the 1RM (-3.77%), and no significant differences were observed for the remaining prediction methods (-0.40-0.86%). The individual L-V relationship could be recommended as the most accurate method for predicting the 1RM during the free-weight prone bench pull exercise.