Change of direction movement is common in sports and the ability to perform this complex movement efficiently is related to athlete's performance. Wearable devices have been used to evaluate aspects of change of direction movement, but so far there are no clear recommendations on specific metrics to be used. The aims of this scoping review were to evaluate the reliability and validity of inertial measurement unit sensors to provide information on change of direction movement and to summarize the available evidence on inertial measurement units in analyzing change of direction movement in sports. A systematic search was employed in MEDLINE (Ovid), CINAHL (EBSCO host), SPORTDiscus (EBSCO host), EMBASE and Cochrane Database of Systematic Reviews and Web of Science to identify eligible studies. A complementary grey literature search was employed to locate non-peer reviewed studies. The risk of bias of the studies evaluating validity and/or reliability was evaluated using the AXIS tool. The initial search identified 15,165 studies. After duplicate removal and full-text screening 49 studies met the inclusion criteria, with 11 studies evaluating validity and/or reliability. There are promising results on the validity and reliability, but the number of studies is still small and the quality of the studies is limited. Most of the studies were conducted with pre-planned movements and participants were usually adult males. Varying sensor locations limits the ability to generalize these findings. Inertial measurement units (IMU) can be used to detect change of direction (COD) movements and COD heading angles with acceptable validity, but IMU measured or derived kinetic or kinematic variables present inconsistency and over-estimation. Studies can be improved with larger sample sizes and agreement on the metrics used and sensor placement. Future research should include more on-field studies.

A b s t r a c t I n t h i s s t u d y a n i n s t r u m e n t i s d e s c r i b e d w h i c h i s u s e d t o q u a n t i t a t i v e l y e v a l u a t e w r i s t j o i n t d y n a m i c s d u r i n g a c t i v e a n d p a s s i v e m o t i o n . T h e t e s t i n s t r u m e n t c o n s i s t s o f a c o m p u t e r c o n t r o l l e d D C s e r v o m o t o r ; t o r q u e , I n o r d e r t o b e t t e r u n d e r s t a n d t h e m e c h a n i s m o f u p p e r e x t r e m i t y s p a s t i c i t y , a n d o t h e r r e l a t e d n e u r o -m u s c u l a r r e s p o n s e s , a n i n s t r u m e n t h a s b e e n d e v e l o p e d w h i c h a l l o u s b o t h p a s s i v e a n d a c t i v e t e s t i n g o f t h e w r i s t j o i n t . l l a t e r i a l s T h e t e s t i n s t r u m e n t i s c o m p o s e d o f m e c h a n i c a l c o m p o n e n t s , t o r q u e a n d d i s p l a c e m e n t t r a n s d u c e r s , s i g n a l c o n d i t i o n i n g e l e c t r o n i c s , a n d a m i c r o c o m p u t e r -b a s e d d a t a a c q u i s i t i o n a n d c o n t r o l s y s t e m . T h e m e c h a n i c a l d e s i g n ( F i g . 1) i s b a s e d u p o n a k i n e m a t i c a n a l y s i s o f a c t i v e a n d p a s s i v e w r i s t j o i n t m o t i o n . I n t h e c o n f i g u r a t i o n , t h e f o r e a r m i s c o m f o r t a b l y s t r a p p e d t o t h e t e s t f i x t u r e a n d k e p t m o t i o n l e s s . T h e h a n d i s a l l o u e d t o r o t a t e a n a t o m i c a l l y a b o u t t h e w r i s t j o i n t t h r o u g h c o m b i n e d a n g u l a r a n d r a d i a l d e g r e e s o f f r e e d o m . B e c a u s e t h e w r i s t j o i n t i s n o t r e v o l u t e , t h e i n s t a n t c e n t e r o f r o t a t i o n i s n o t f i x e d . D i s p l a c e m e n t s r e s u l t i n g f r o m c o m p l e x w r i s t j o i n t m o t i o n a r e q u a n t i f i e d b y t h e c o m b i n e d a n g u l a r a n d r a d i a l d i s p l a c e m e n t s . B e c a u s e t h e m o t i o n i s u n c o n s t r a i n e d , i t o c c u r s f r e e l y w i t h o u t c r e a t i n g a b n o r m a l j o i n t f o r c e s . T h e d e v i c e i s d r i v e n b y a 3 7 3 U O C e l e c t r i c m o t o r c o n n e c t e d t h r o u g h a p r e c i s i o n 20:1 g e a r d r i v e . T h e o u t p u t s h a f t i s c o n n e c t e d t o t h e d r i v e -a r m t h r o u g h ar e a c t i o n t o r q u e t r a n s d u c e r ( s t r a i n g a g e ) . R e s i s t i v e w r i s t j o i n t t o r q u e s a r e a p p r o x i m a t e d b y t h i s t r a n s d u c e r . A r o t a t i o n a l p o t e n t i o m e t e r i s a l s o c o n n e c t e d t o t h e d r i v e s h a f t , a s e r e b a c k u p s a f e t y l i m i t s w i t c h e s a n d m e c h a n i c a l s a f e t y s t o p s t o p r e v e n t i n j u r y i n c a s e o f a c o n t r o l l e r f a i l u r e . T h e D C m o t o r i s c o n t r o l l e d b y a s e r v o s y s t e m w h i c h u t i l i z e s v e l o c i t y c o n t r o l . I n t h i s mode, t h e p u l ...

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The objective of this study was to develop a biomechanical model of passive wrist motion in children with spastic cerebral palsy. A motorized test system was used to gather the passive motion data for the study (1). The model of the spastic hypertonic response to passive motion is shown to provide a reliable method of assessment which correlates well with clinical findings.