Validity and Reliability of Dynamic and Functional Balance Tests in People Aged 19-54: A Systematic Review.

Evaluating an impairment in an individual's capacity to maintain, achieve, or restore balance suggests a deficiency in postural control. For effective identification of individuals at risk for falls, balance assessment should exhibit reliability, validity, and ease of use. This systematic review concentrated on dynamic and functional balance assessment methods and their validity in healthy adults aged 19-54. The objective was to clarify the tools that health professionals can utilize to assess balance in this healthy population. Methods: A systematic literature search conducted in August 2019 yielded nine articles meeting predefined selection criteria. Inclusion criteria required studies featuring healthy adult participants aged 19-54, published in English, and focusing on dynamic and functional balance testing. Exclusion criteria excluded studies involving participants with chronic diseases or musculoskeletal disorders, systematic reviews, professional athletes, and those lacking specific participant age information. The quality of the studies was evaluated using a modified PEDro scale. Results: This review analyzed ten distinct postural balance tests. The Star Excursion Balance Test and Y-Balance Test exhibited moderate to high reliability, establishing them as dependable measures of dynamic balance. The Nintendo Wii Balance Board, Clever Balance Board, and Posturomed device also displayed excellent reliability for assessing dynamic postural balance. Comparing one-arm and two-arm functional reach tests, the one-arm reach test emerged as a more suitable option for evaluating dynamic balance among young adults. Moreover, an investigation comparing three dynamic balance tests (one-leg jump landing, Posturomed device, and stimulated forward fall) revealed a low correlation among these tests, indicating a measurement of different balance constructs. Discussion: In conclusion, the Y-Balance Test stands out as the most practical dynamic balance assessment for clinical use, characterized by a standardized protocol, good repeatability, affordability, and ease of application. The Nintendo Wii Balance Board also presents itself as a cost-effective and reliable tool for dynamic balance evaluation in clinical settings. It is crucial to recognize that these tests appraise discrete postural skills, preventing direct comparisons between test outcomes. This review equips healthcare professionals with valuable insights into optimal balance assessment methods for the healthy, 19 to 54 aged population. Levels of evidence: Level 3.

In vivo assessment of the passive stretching response of the bicompartmental human semitendinosus muscle using shear-wave elastography.

The semitendinosus muscle contains distinct proximal and distal compartments arranged anatomically in series but separated by a tendinous inscription, with each compartment innervated by separate nerve branches. Although extensively investigated in other mammals, compartment-specific mechanical properties within the human semitendinosus have scarcely been assessed in vivo. Experimental data obtained during muscle-tendon unit stretching (e.g., slack angle) can also be used to validate and/or improve musculoskeletal model estimates of semitendinosus muscle force. The purpose of this study was to investigate the passive stretching response of proximal and distal human semitendinosus compartments to distal (knee) joint extension. Using two-dimensional shear-wave elastography, we bilaterally obtained shear moduli of both semitendinosus compartments from 14 prone-positioned individuals at 10 knee flexion angles [from 90° to 0° (full extension) at 10° intervals]. Passive muscle mechanical characteristics (slack angle, slack shear modulus, and the slope of the increase in shear modulus) were determined for each semitendinosus compartment by fitting a piecewise exponential model to the shear modulus-joint angle data. We found no differences between compartments or legs for slack angle, slack shear modulus, or the slope of the increase in shear modulus. We also found that the experimentally determined slack angle occurred at ∼15°-80° higher knee flexion angles compared with estimates from two commonly used musculoskeletal models, depending on participant and model used. Overall, these findings demonstrate that passive shear modulus-joint angle curves do not differ between proximal and distal human semitendinosus compartments and provide experimental data to improve semitendinosus force estimates derived from musculoskeletal models.NEW & NOTEWORTHY We conducted an elastography-based investigation of the passive stretching response of the proximal and distal compartments of the human semitendinosus muscle and found no difference in shear modulus-joint angle curves between compartments. We also found that common musculoskeletal models tend to misestimate semitendinosus slack angle, most likely due to typical model assumptions. These results provide an important step toward a better understanding of semitendinosus passive muscle mechanics and improving computational estimates of muscle force.

Lower limb muscle activation patterns in ice-hockey skating and associations with skating speed.

In this study, we aimed to describe lower limb kinematic and muscle activation patterns and then to examine the potential associations between those variables and skating speed in highly trained ice-hockey players. Twelve players (age 18.4-22.0 years) performed five maximal 30-metre forward skating sprints. Skating speeds, muscle activities from eight lower limb muscles (gluteus maximus, gluteus medius, adductor magnus, rectus femoris, vastus lateralis, biceps femoris, tibialis anterior and soleus), and sagittal plane joint angles from the hip and knee joint were measured. A lower activity of the gluteus maximus (r = -0.651, p = 0.022, ß = -0.08) and a reduced gluteus maximus to rectus femoris coactivity (r = -0.786, p = 0.002, ß = -3.26) during the recovery phase were found to be associated with faster skating speed. No significant associations were observed between sagittal plane hip and knee kinematics and skating speed. This study provides evidence that muscle activities during the recovery phase of skating may have an important role in skating performance.

A Perturbed Postural Balance Test Using an Instrumented Treadmill - Precision and Accuracy of Belt Movement and Test-Retest Reliability of Balance Measures.

A perturbed postural balance test can be used to investigate balance control under mechanical disturbances. The test is typically performed using purpose-built movable force plates. As instrumented treadmills become increasingly common in biomechanics laboratories and in clinical settings, these devices could be potentially used to assess and train balance control. The purpose of the study was to investigate how an instrumented treadmill applies to perturbed postural balance test. This was investigated by assessing the precision and reliability of the treadmill belt movement and the test-retest reliability of perturbed postural balance test over 5 days. Postural balance variables were calculated from the center of pressure trajectory and included peak displacement, time to peak displacement, and recovery displacement. Additionally, the study investigated short-term learning effects over the 5 days. Eight healthy participants (aged 24-43 years) were assessed for 5 consecutive days with four different perturbation protocols. Center of pressure (COP) data were collected using the force plates of the treadmill while participant and belt movements were measured with an optical motion capture system. The results show that the treadmill can reliably deliver the intended perturbations with <1% deviation in total displacement and with minimal variability between days and participants (typical errors 0.06-2.71%). However, the treadmill was not able to reach the programmed 4 m/s2 acceleration, reaching only about 75% of it. Test-retest reliability of the selected postural balance variables ranged from poor to good (ICC 0.156-0.752) with typical errors between 4.3 and 28.2%. Learning effects were detected based on linear or quadratic trends (p < 0.05) in peak displacement of the slow forward and fast backward protocols and in time to peak displacement in slow and fast backward protocols. The participants altered the initial location of the COP relative to the foot depending on the direction of the perturbation. In conclusion, the precision and accuracy of belt movement were found to be excellent. Test-retest reliability of the balance test utilizing an instrumented treadmill ranged from poor to good which is, in line with previous investigations using purpose-built devices for perturbed postural balance assessment.