Test-Retest Reliability of Measurements of the Center of Pressure Displacement in Quiet Standing and During Maximal Voluntary Body Leaning Among Healthy Elderly Men

The aim of the study was to evaluate intra- and intersession test-retest reliability for the measurements of centre of pressure displacement in quiet standing and during maximal voluntary body leaning (approximate area of stability limits). 27 elderly men participated in the study (71.4±4.9 of age). Intrasession (4 measurements with two-minute breaks) and intersession (4 measurements one week apart) reliability were examined. Parameters connected to the centre of pressure data (AMTI force platform) were measured during a quiet stance and voluntary body leaning in medio-lateral and anterior-posterior directions (approximate limits of stability). Intraclass correlation coefficients (ICC2,1 and ICC2,k) were calculated. In case of quiet standing, only mean velocity of centre of pressure sway provides high reliability in intrasession - ICC2,1 of .84 and ICC2,k of .96, and in intersession - ICC2,1 of .76. Evaluation of limits of stability showed high values of all parameters (maximal and minimal displacement in sagittal and frontal planes, distance between maximal and minimal position of centre of pressure in sagittal and frontal planes and approximated area of stability limits) in intrasession - ICC2,1 between .82 to .96 and ICC2,k between .95 to .99. Similar tendency was observed in the intersession retest. Average velocity of the centre of pressure is the only parameter that showed a high application value in case of measurements during quiet standing. Parameters related to the stability limits appeared very reliable what proves that this evaluation may have potential application in the clinical practice.