Between-session reliability of dry-land and in-water tests to measure inter-limb asymmetries in swimmers

ABSTRACT

The aims of the present study were to: i) analyse the between-session reliability of dry-land and in-water swimming tests, and ii) investigate the prevalence of meaningful asymmetries in swimming athletes. Twenty-eight swimmers (21 males, 7 females) performed anthropometric, shoulder range of motion (ROM), countermovement jump, shoulder isokinetic torque, and 15-s tethered swimming tests two times, 1 week apart. Inter-limb asymmetries were calculated for each variable. Raw data reliability was determined using the intraclass coefficient correlation (ICC) and the typical error of measurement (TEM), and effect size (ES) was used to determine systematic bias between test sessions. At an individual level, inter-limb asymmetries were compared to the coefficient of variation (CV) to determine whether they were real. The between-session reliability was good to excellent (0.75 to 1.00) for most of the raw data, except for ROM. Between-session ES was predominately “trivial” or “small” for raw data and asymmetries, reinforcing that the values did not change significantly between the sessions. In addition, real asymmetries were seen in some tested metrics, depending on the test. In conclusion, the tested variables presented good levels of between-session reliability and were able to detect real and consistent asymmetries.

KEYWORDS:

• Swimming
• side-to-side differences
• performance
• biomechanics

Acknowledgments

The authors would like to thank the swimmers for their participation. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Practical applications

• The present evidence suggests that the tested variables are good choices for coaches and researchers aiming to measure asymmetries in swimmers, since they present good levels of between-session reliability.

• Asymmetries are shown to be “real” in most athletes evaluated, so it is necessary to understand and monitor the possible implications on performance and/or injuries.

• The magnitude and direction of asymmetry in swimmers vary between individuals. These results highlight the need for individual and periodic asymmetry analysis in this population, together with robust methods that establish “signal to noise” within the context of limb differences. Once achieved, this may help practitioners determine whether targeted interventions are necessary.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.