Four-way-leaning test shows larger limits of stability than a circular-leaning test.
Limits of stability (LOS) have extensive clinical and rehabilitational value yet no standard consensus on measuring LOS exists. LOS measured using a leaning or a circling protocol is commonly used in research and clinical settings, however differences in protocols and reliability problems exist.



This study measured LOS using a four-way-leaning test and a circular-leaning test to test which showed larger LOS measurements. Furthermore, number of adaptation trials needed for consistent results was assessed.



Limits of stability were measured using a force plate (Metitur Good Balance System®) sampling at 50Hz. Thirty healthy subjects completed 30 trials assessing LOS alternating between four-way-leaning test and circular-leaning test.



A main effect of methods (ANOVA:F(1,28)=45.86, P<0.01) with the four-way-leaning test showing larger values than the circular-leaning test (NK, P<0.01). An interaction between method×directions was found (ANOVA:F(3, 84)=24.87, P<0.01). The four-way-leaning test showed larger LOS in anterior (NK, P<0.05), right (NK, P<0.01) and left direction (NK, P<0.01). Analysis of LOS for the four-way-leaning test showed a difference between trials (ANOVA:F(14,392)=7.81, P<0.01). Differences were found between trial 1 and 7 (NK, P<0.03), trial 6 and 8 (NK, P<0.02) and trial 7 and 15 (NK, P<0.02). Four-way-leaning test showed high correlation (ICC>0.87) between first and second trial for all directions.



Four-way-leaning test yields larger LOS in anterior, right and left direction making it more reliable when measuring LOS. A learning effect was found up to the 8th trial, which suggests using 8 adaptation trials before reliable LOS is measured.
Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
Mikkel Højgaard
MH
Thomsen
Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
Nicolai
N
Støttrup
Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
Frederik Greve
FG
Larsen
Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
Ann-Marie Sydow Krogh
ASK
Pedersen
Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
Anne Grove
AG
Poulsen
Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark; Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark,. Electronic address: hirata80@gmail.com.
Rogerio Pessoto
RP
Hirata
D000328:Adult; D005260:Female; D006801:Humans; D007858:Learning; D059032:Learning Curve; D008297:Male; D004856:Postural Balance / Q000502:physiology*; D015203:Reproducibility of Results; D055815:Young Adult
Adaptation trials; Center of pressure; Limits of stability; Method comparison; Postural control