Assessment of age-related changes in core stability and postural health

 

Erika Zemková

1 Department of Sports Kinanthropology, Faculty of Physical Education and Sport, Comenius University in Bratislava, Slovakia

2 Sports Technology Institute, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology in Bratislava, Slovakia

 

Many sports and everyday activities require good core stability and effective postural response mechanisms. Therefore their assessment should be considered an integral part of physical fitness testing in athletes as well as general population.

Recently, a Long-Term Sport Diagnostic Model was proposed (Zemková, 2014; Zemková, 2015a), which was afterwards modified into following age-related stages: Stage 1 (6 to 9 years), Stage 2 (10 to 14 years), Stage 3 (15 to 18 years), Stage 4 (19 to 24 years), Stage 5 (25 to 44 years), Stage 6 (45 to 64 years), and Stage 7 (65+ years) (Zemková, 2018a; Zemková, 2019a). This model includes also tests of postural and core stability in particular age periods (Table 1).

 

Table 1 Postural and core stability tests within seven stages of a Long-Term Sport Diagnostic Model

Stages 1 - 3	Stages 4 - 6	Stage 7
	Static balance tests
Task-oriented balance tests (Visually-guided CoM target-matching task)		Task-oriented balance tests (Visually-guided CoM tracking task)
	Perturbation-based balance tests	Perturbation-based balance tests
	Dynamic balance tests
	Torsional tests
Tests of spinal stability		Tests of spinal stability

 

Measurement of core stability involves the incorporation of variables of balance and coordination. Core stability tests usually require the individual to maintain a neutral spinal posture in a quadrupedal or supine position that involves activation of local core muscles. Other tests, such as the Biering-Sørensen test of lumbar extension or the flexor and side bridge endurance tests assess the static muscular endurance of global core muscles. Another examples are instrumented torsional tests, which can be performed on either a stable or an unstable support surface. During these tests, basic stabilographic parameters can be registered using the posturography systems based on a force plate. We have found that postural and core stability under unstable conditions are better in female than male subjects, whereas males perform better when core stability is maintained on a stable support surface (Zemková, 2019b).

Similarly, postural stability can be evaluated under both static (bipedal or one-legged stance on a stable platform with eyes open and eyes closed) and dynamic conditions (a stance on a foam cushion or a spring-supported platform, external perturbations generated from a platform either shifting in antero-posterior and medio-lateral direction or tilting toes up and down, and applying them directly to the body by pushing/pulling the trunk, shoulders or pelvis).

However, frequently used static posturography in most cases is not sensitive enough to differentiate balance performance in physically active individuals. Lower sensitivity of static posturography is a consequence of multiple sensory inputs (visual, vestibular, and proprioceptive) involved in postural control. Such a system can compensate for a smaller impairment of balance in such a way that under normal conditions (stance on a stable surface) no deficits in postural stability may be apparent. Under dynamic conditions (stance on an unstable surface), the control mechanisms are taxed to a substantially higher extent so that individual differences can be revealed.

Indeed, standing on an unstable foam surface or a spring-supported platform while testing body balance is more efficient in discriminating within-group and between-group differences when compared to static balance tests (Zemková, Hamar, 2015; Zemková et al., 2015c). A recent study showed that unstable conditions improve the discriminatory accuracy of balance tests with both eyes open and eyes closed in healthy young, early and late middle-aged adults (Zemková et al., 2018).

Also the dynamic posturography in many cases represents more specific and hence more appropriate alternative for the assessment of balance than systems allowing for monitoring of the CoP variables in static conditions. Various protocols, based on varied determinants of plate translation, such as the direction, displacement, and velocity can be designed (Zemková et al., 2015b). Concurrently with measurement of CoP movement, trunk movement representing roughly the center of mass (CoM) can also be monitored. We have found that postural and trunk responses to unexpected perturbations depend on the velocity and direction of platform motion (Zemková et al., 2016b). Specifically, the velocity of perturbation alters peak CoM velocity rather than the magnitude of CoM displacement. The effect of the direction of perturbations on the trunk response emerges only at a high velocity of platform motion, such that the peak CoM velocity and peak CoM acceleration are significantly greater in the anterior than posterior direction. However, most of these posturography systems have been employed mainly for clinical examination of patients with balance disorders. The practice implies that computerized portable devices that are more applicable to routine testing in the field are preferred over laboratory techniques.

A suitable alternative represents perturbation based balance tests. In the case of the trunk repositioning task, the subject has to passively or actively return to a neutral spine position after a predefined displacement. The load release task requires the subject to perform an isometric contraction of trunk muscles at a predefined intensity against an external load, which is thereafter released, and the trunk displacement is evaluated. This test conducted under unstable conditions is able to differentiate between groups of physically active and sedentary adults as early as from 19 years of age (Zemková et al., 2016d).

Also task-oriented balance tests are more sensitive in discriminating between group differences than tests performed under stable conditions (Zemková, 2017). In addition, the accurancy of static balance tests can be influenced by factors, such as motivation or attentiveness, which are difficult to control in young and also elderly individuals. While the test in a form of visually-guided CoM target-matching task is better for children and youth, for elderly people the test in a form of visually-guided CoM tracking task represents a more appropriate alternative. A moderate correlation between parameters of these task-oriented balance tests (r = 0.46) and the common variance of 13% indicates that they assess distinct qualities. This is because voluntary feedback control of body position is performed under different conditions, i.e. the subject is focused either on the goal of the task (i.e. hitting the target) or on movement themselves (i.e. the positioning of the CoM). These test differences allow assessment of accuracy of regulation of body movement that requires less or more feedback processing. This is of special importance for children who regulate their CoM movement in a more conscious, effortful fashion (i.e. observed as a longer CoP trajectory) with their decisions about the action being handled in a slow, attention-demanding way (i.e. shown as a slower response time).

These tests can be completed with measurements of spinal curvature using a non-invasive surface-based techniques (Muyor et al., 2014). Additional data on functional balance can be obtained using techniques based on motion analysis or accelerometry recordings while evaluating head, limb and trunk movements. The use of trunk accelerometry is a cost-effective and easily applied solution for measuring body balance and human movement. With the advent of fast wireless technology and low-cost accelerometers, their use in the field-testing of various aspects of balance is now feasible.

 

Conclusion

Taking into account the importance of body balance and core stability in most sporting and daily activities, their assessment should be considered an integral part of the functional testing in physically active individuals as well as those with a predominantly sedentary life style (Zemková, 2015b; Zemková a kol., 2015a; Zemková, 2018b). This study presented our experience with applications of postural and core stability tests in the assessment of subjects of different ages and levels of physical fitness (Zemková, 2011; Zemková a kol., 2016a; Zemková a kol., 2016c; Zemková a kol., 2017; Zemková, Hamar, 2018). Revealing changes in balance functions across the lifespan can provide useful information for designing the individually tailored exercise programs (Zemková, 2010), which may contribute to the enhancement of athletic performance and/or decrease the risk of falls and fall-related injuries in general population.

 

Acknowledgments

This work was supported by the Scientific Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Republic and the Slovak Academy of Sciences (No. 1/0824/17) and the Slovak Research and Development Agency under the contract No. APVV-15-0704.

 

References

Muyor, J. M., Zemková, E., Štefániková, G., & Kotyra, M. (2014). Concurrent validity of clinical tests for measuring hamstring flexibility in school age children. International Journal of Sports Medicine, 35(8), 664‒669. doi: 10.1055/s-0033-1353217

Zemková, E. (2010). Sensorimotor exercises in sports training and rehabilitation. In: M. J. Duncan & M. Lyons (Eds.). Trends in Human Performance Research. New York: Nova Science Publishers, Inc., 79-117.

Zemková, E. (2011). Assessment of balance in sport: Science and reality. Serbian Journal of Sports Sciences, 5(4), 127-139.

Zemková, E. (2014). Our approach to physical performance testing of school age children. Potchefstroom: Global Forum for Physical Education Pedagogy.

Zemková, E. (2015a). Functional performance testing across the lifespan. MR International Journal of Applied Health Sciences, 2(1), 26-41.

Zemková, E. (2015b). State of the art assessment of core stability and core  strength. Smolenice: 7th International Posture Symposium, 91

Zemková, E., & Hamar, D. (2015). Between-subjects differences in CoP measures on stable and unstable spring-supported platform. Sevilla: World Congress of the International Society for Posture & Gait Research, 131.

Zemková, E., Jeleň, M., Poór, O., & Štefániková, G. (2015a). Novel methods for the assessment of postural and core stability in sport and rehabilitation. Bratislava: 19th International Scientific Conference on Sport, 1–11.

Zemková, E., Kováčiková, Z., Jeleň, M., Neumannová, K., & Janura, M. (2015b). Methodological issues of dynamic posturography specific to the velocity and the displacement of the platform perturbation. Proceedings of scientific studies “From Research to Practice in Sport”, 1-10.

Zemková, E., Muyor, J. M., Štefániková, G., Svoboda, Z., & Janura, M. (2015c). Nestabilné podmienky diferencujú fyzicky aktívnych jedincov a so sedavým spôsobom života s rôznou úrovňou stability postoja a trupu. Medicina Sportiva Bohemica & Slovaca, 24(3), 147. 

Zemková, E., Hamar, D., Kienbacher, T., & Ebenbichler, G. (2016a). Clinical applications of posturography: from research to practice. Slovak Journal of Health Sciences, 7(2), 59-77.

Zemková, E., Kováčiková, Z., Jeleň, M., Neumannová, K., & Janura, M. (2016b). Postural and trunk responses to unexpected perturbations depend on the velocity and direction of platform motion. Physiological Research, 65(5), 769-776.

Zemková, E., Kyselovičová, O., Ukropec, J., & Ukropcová, B. (2016c). Unique functional performance testing for the overweight and obese. Medicina Sportiva Practica, 17(1), 1-8.

Zemková, E., Štefániková, G., & Muyor, J. M. (2016d). Load release balance test under unstable conditions effectively discriminates between physically active and sedentary young adults. Human Movement Science, 48(1), 142-152. doi: 10.1016/j.humov.2016.05.002

Zemková, E. (2017). Functionally directed balance testing: Are task-oriented balance tests a future? Collegium Antropologicum, 41(4), 383-389.

Zemková, E., Hamar, D., Kienbacher, T., & Ebenbichler, G. (2017). Assessment of core stability and strength: from theory to practical applications. Slovak Journal of Health Sciences, 8(2), 64-81.

Zemková, E. (2018a). Functional testing across early stages of long-term athlete development. Journal of Physical Education and Sports Science, 11(2), 8-14.

Zemková, E. (2018b). Science and practice of core stability and strength testing. Physical Activity Review, 6, 181-193. doi: 10.16926/par.2018.06.23

Zemková, E., & Hamar, D. (2018). Sport-specific assessment of the effectiveness of neuromuscular training in young athletes. Frontiers in Physiology, 9, 264. doi: 10.3389/fphys.2018.00264

Zemková, E., Andreeva, A., & Hamar, D. (2018). Discriminatory accuracy of balance tests improves under altered stance support conditions. Smolenice: 8th International Posture Symposium, 126-127.

Zemková, E. (2019a). Functional testing across middle and late stages of long-term athlete development. Tiruchirappalli: International Congress on Renaissance in Sports „Strategies, Challenges and Choices“, 85-87.

Zemková, E. (2019b). Instrumented torsional tests in an assessment of between-gender differences in core stability. Bratislava: 22nd International Scientific Conference „From Reseaech to Practice“, 97-103.