Lower Extremity Preference During Gross and Fine Motor Skills Performed in Sitting and -

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1 Lower Extremity During Gross and Fine Motor Skills Performed in Sitting and - Standing Postures )anna Beling, PhD, PT ' George A. Wolfe, Ph D, PT * Kathryn A. Allen, MPT~ jeanine M. Boyle, MPT4 L ateralization in motor control, exemplified by either footedness or handedness, is clinically obse~vable. Extensive research has been dedicated to the understanding of laterality (5,10,11). Laterality is defined as a functional predominance of one side of the body or language-related dominance of one cerebral hemisphere (6). Several theories have been developed to explain laterality, and studies have been done to determine whether an individual has functional predominance of a particular side of the body ( 1,2,8,9,13). Handedness refers to the preferential use of one hand for fine motor activities, such as writing or eating. edness refers to the preferential use of one foot for fine motor activities, such as kicking a ball or picking a marble up with the toes. By convention, the preferred limb is the limb acting on and manipulating an ob ject, whereas the nonpreferred limb is used as a postural and stabilizing support (11). Laterality patterns of foot preference in left-handed individuals are not as consistent as in right-handed individuals when performing a specific activity (12). However, no research has been reported regarding whether varying the type of activity or the weight-bearing status The evaluation of lower limb preference in physical therapy practice is critical in order for the clinician to assist patients with functional retraining tasks. No studies in the physical therapy literature present a systematic approach to determine the criteria needed to identify the preferred limb. This research was designed to present a series of tests for effectiveness in determining limb preference. The purpose of this study was to determine whether lower limb preference existed in a group of recreationally athletic women when performing either stability or dynamic skills with the lower extremities while sitting or standing. The relationship of such a preference to handedness was also determined. Forty female recreational athletes, 20 right-handed subjects and 20 lefthanded subjects, who ranged in age from 21 to 35 years, participated in this study. Subjects performed three repetitions of the following tests in both sitting and standing: kick a ball, swing a leg over a box, pick up a marble with the toes, and trace a triangle with the toes. The subjects were abo asked to stand on one leg. The order of performing the tests was randomized. The results indicated that right-handed subjects performed activities more consistently with one lower extremity when compared with left-handed subjects, regardless of posture (sitting or standing). The difference in limb choice between right- and left-handed subjects was significant for all activities (p <.05). The considerable sensitivity of foot and leg performance following neurological insult renders the assessment of foot and leg preference very important for purposes of clinical rehabilitation. Key Words: motor control, kicking, foot preference, hand preference, laterality ' Associate Professor, Division of Physical Therapy, Chapman University, 333 N. Glassell Street, Orange, CA Chairperson and Associate Professor, Division of Physical Therapy, California State University, Northridge, CA ' Senior Physical Therapist, Outpatient Physical Therapy Department, University of California, 10s Angeles, Westwood, CA Physical Therapist, Clinishare Home Health, long Beach, CA (sitting or standing) changes the preference for the foot used in performing a skill. Evaluation of limb preference in physical therapy practice is critical in order for the clinician to assist patients with functional retraining tasks. It is essential that an accurate test for the determination of lower extremity preference is available. The clinical information from this test may explain strength differences between limbs as well as differences in learning curves of functional skills between limbs. In isokinetic evaluation or research, for example, the deter- Volume 28 Number 6 December 1998 rn JOSF'T

2 , -., " RESEARCH STUDY ? mination of limb preference might influence the interpretation of certain evaluation procedures. The purpose of this study was two-fold. One purpose was to determine whether limb preference existed in a group of healthy women when performing either stability or dynamic skills with the lower extremities while sitting or standing. The relationship of such a preference to handedness was also determined. The authors analyzed the use of selected tasks in order to determine lower limb preference and suggested clinical tools of limb preference determination. Bipedal tasks reduce flexibility in lateral expression and, therefore, provide more information than unipedal tasks. METHODS Subjects Forty female subjects, ranging from 21 to 35 years of age (X = 27 years) participated in this study. All subjects were members of women's softball leagues throughout Southern California. None of the subjects had a history of a diagnosed disease or disability due to orthopaedic or neurological abnormality. Informed consent was obtained from all subjects, consistent with the policies of the Institutional Review Board of Children's Hospital Los Angeles, Los Angeles, CA. Instrumentation The equipment used in this study consisted of a wooden box [35.9 (height) X 45 (width) X 27.5 (depth) cm], a straight back chair [chair seat: 45.5 (height) X 45 (width) X 39.4 (depth) cm], a marble (5.3 cm in circumference), a ball (23 cm in circumference), a premarked plastic mat (Figure), and a digital stopwatch. The mat used for the placement of instruments during the testing was marked for the following items: foot JOSPT Volume 28 Number 6 December 1998 FIGURE. Plastic mat with premarkings for chair, feet, triangle, and box positions. placement, an equilateral triangle, a box, a ball, and a marble. The premarked feet were centered between the legs of the chair. The markings for the heels of the feet were placed 13 cm from the legs of the chair. The equilateral triangle (each side = 7.6 cm) was 6 cm in front and equally spaced between the two feet. The mark for the box placement was 37 cm in front and equally placed between the legs of the chair. The ball and marble were placed on a dot in the center of the equilateral triangle. Procedure Handedness was defined as the hand with which the subjects wrote. Twenty right-handed subjects and 20 left-handed subjects participated in the testing. Each subject was randomly assigned an order to perform three repetitions of each activity. The lower extremity with which each subject chose to perform a selected activity two out of three trials was recorded. The following tests were designed to identify the lower extremity used for gross dynamic activi- ties: 1) 2) The subject, while standing on placement, was asked to kick a ball placed on the premarked spot. The subject was given the command "kick the ball hard." The subject, while sitting in a was asked to kick a ball placed on the premarked spot. The subject was given the command "kick the ball hard." 3) The subject, while standing on placement, was asked to swing a leg over the box. The box was placed on the premarked spot. 4) The subject, while sitting on a was asked to swing a leg over the box. The box was placed on the premarked spot. The following tests were designed to identify the lower extremity used for fine dynamic activities: 1) The subject, while standing barefoot on the premarked mat for foot placement, was asked to pick up a marble with her toes. The marble was placed on the premarked spot. 2) The subject, while sitting barefoot in a chair with both feet on placement, was asked to pick up a marble with her toes. The marble was placed on the premarked spot. 3) The subject, while standing on placement, was asked to trace a premarked equilateral triangle on the mat with the tip of her toe. 4) The subject, while sitting in a was asked to trace the same equilateral triangle with the tip of her toe. In standing trials, the limb chosen for weight bearing during two out of three trials was noted and was termed the static limb. In addition,

3 RESEARCH STUDY.. TABLE 1. preierence oi right-handed individuals for gross dynamic tests. the subjects were asked to stand on one leg for 5 seconds. Data Analysis A chi-square analysis was used to determine if there was a difference between right- and left-handed women in the frequency with which the right or the left leg was chosen for any given activity. Chi-square was used to determine if posture affected the lower extremity chosen. A chisquare analysis was also used to examine the possible influence of the type of activity on lower limb preference. RESULTS Over 90% of the time, righthanded subjects stood on the left leg during performance of a gross or fine dynamic skill with the right foot (Tables 1 and 2). When asked to stand on one leg, the right-handed subjects chose the left leg 45% of the time (Table 3). -handed subjects were much less consistent with their limb preference during dynamic skills. -handed subjects stood on the right leg 60-80% of the time Adivity (N = 20) Rieht Sit picking marble up with toes 19 1 Stand picking marble up with toes 19 1 Sit tracing triangle with toes 18 2 Stand tracing triangle with toes 20 0 JL~IIU ~ I C K I Illldlulr I ~ ~ up WIUI LU~S I 1'1 Stand tracing triangle with toes 0 20 Stand on one leg 11 9 TABLE 3. preierence oi right-handed individuals for static tests. during performance of a dynamic skill 4th the left foot (Tables 4 and 5). When asked to stand on one leg, they stood on the right leg 25% of the time (Table 6). Posture (sitting or standing) for both right- and lefthanded subjects did not change the lower extremity chosen for a given activity. The difference in limb choice was significant for all activities (p <.05) between right- and lefthanded subjects. DISCUSSION This study was designed to present a series of tests that could be used as a baseline in future testing when determining limb preference. There are many definitions of footedness found in the literature. edness is defined as the foot used to manipulate an object or to lead out, as in jumping (11). edness has also been defined as the leg of preference in kicking (5). Other authors have determined footedness by asking subjects which foot was used to kick a ball, step up onto a chair, and pick up a pebble (9,lO). One study reported that 60% of individuals Adivii (N = 20) Right Sit kicking ball 8 12 Stand kicking ball 8 12 Sit swing leg over box 5 15 Stand swing leg over box tested preferred the right foot for stepping up onto a chair, and 53% preferred the right foot for stepping down from a chair (6). Therefore, tests of climbing prove not to be a clear indicator for distinguishing limb preference (63). We define footedness as the preferential use of one foot for dynamic motor activities, not static activities. There are many theories concerning the origins of lateralization in humans (l,2,8,9,13). Genetic, accidental, and cultural factors may all have a role in the development of limb preference (1). Annett's model of laterality proposes a genetic rightshift tendency for right handers, which may have a cultural influence (1). The model proposes no directional predisposition for left handers. This model accounts for the strong right-foot preference of right handers and the reduced consistency in lateral foot preference in left handers. The results of the present study indicate that left-handed individuals are much less consistent in limb preference than right-handed individuals. These results are consistent with the published results of other studies. It TABLE 5. preierence of leit-handed individuals for iine dynamic tests. Activity (N = 20) Right Stand kicking a ball 12 8 Stand swing leg over box 14 6 Stand picking marble up with toes 14 6 Stand tracing triangle with toes 15 5 Stand on one leg 5 15 TABLE 2. preierence oi right-handed individuals TABLE 4. preference oi /en-handed individuals TABLE 6. preference of IeA-handed individuals for iine dynamic tests. for gross dynamic tests. for static tests. 402 Volume 28 Number 6 December JOSIT

4 RESEARCH STUDY has been reported that 92% of righthanded individuals are right footed and only 51% of left-handed individuals are left footed (5). A majority of right-handed individuals tend to kick with the right foot, whereas lefthanded individuals show no preference for kicking with the left foot (2). In a similar test study, 95% of right-handed individuals preferred to kick a ball with the right foot, and 50% of left-handed individuals preferred to kick the ball with the left foot (12). In the present study, 100% of the right-handed individuals preferred to kick a ball with their right foot, and only 60% of the left-handed individuals preferred to kick the ball with their left foot. These results were not affected by changing to a sitting posture. It has been demonstrated elsewhere that right-handed individuals tended to use the right foot to pick up small objects, whereas left-handed individuals tended to use the left foot (2,l4). The present study indicated that over 70% of the left-handed individuals preferred to use the left foot to pick up a marble whether sitting or standing. Ninetyfive percent of right-handed individuals preferred to use the right foot either in sitting or standing to pick up a marble. There are no published data on the effect of posture on lower limb preference. Lifting a pebble is a good foot preference task because it forces a clear division of functional roles of the two feet in terms of a foot that manipulates and one that supports (1 1). However, this is only so if the subject is standing, forcing a choice of which leg is used for support and which is used for manipulation. No particular leg, however, is used for support when a person is seated. On the basis of the present study's results, then, it can be concluded that the foot or leg used for dynamic activities is typically lateralized to the same side as the dominant hand regardless of posture. This is more consistent in right handers than left handers. It appears that an individual's limb preference is dependent upon the type of activity. When given an activity that requires a dynamic and static component, there appears to be a consistency in limb preference for that task (p <.01). Whereas, when an individual is asked to stand on one leg in which no dynamic activity is involved, the choice of the leg becomes more variable (p <.05). An activity with a dynamic component appears to be the determining factor for limb preference. Therefore, an activity with a dynamic component appears to be the determining factor for limb preference. This study has clinical implications for the physical therapist. When assessing limb preference, footedness must be defined. edness refers to the preferential use of one foot for dynamic motor activities. It is important that each testing activity consists of a dynamic component because this appears to increase the consistency in limb preference. Chapman et al, for example, found that the measure "stand on one foot" correlated extremely poorly with other measures of footedness (3). Therefore, the test of standing on one leg is not a clear indicator of limb preference because it does not involve a dynamic component. If lower limb preference is defined in terms of a reliable role differentiation of the two feet and legs, female right handers show a clear (90%) right-foot bias for activities requiring both gross and fine dynamic manipulation and focused attention whether sitting or standing. The literature makes it clear that the right foot tends to be the preferred foot of right handers (2,5,12,14). In adult right handers, the left leg tends to be the heavier one, in keeping with the support role of that leg (4). The situation is less clear in left handers because of the pattern of a reduced consistency in lateral preference in the foot as shown in the present study and others (2,5,12). preference tests can be useful adjuncts to evaluation because foot preference is a sensitive indicator of problems in motor control (7). The considerable sensitivity of foot and leg performance following neurological insult renders the assessment of foot and leg use very important for purposes of clinical rehabilitation. CONCLUSION In conclusion, this study was designed to present a series of tests that could be used by physical therapists when determining a patient's limb preference. These conclusions may be applicable only to women. Female recreational softball players were used as subjects in an attempt to control for psychomotor ability. Future studies should examine the determination of limb preference in men, different age groups, control of psychomotor ability, and the coordination between limb preference and assistive device use in gait. Based on the above test results using 40 female subjects, 20 right-handed and 20 lefthanded, performing both dynamic and static activities, the following conclusions were drawn: -handed women tend to be less lateralized than right-handed women. This information is especially useful in the understanding of foot use in left-handed patients who perform different skilled tasks with different feet. Posture, either sitting or standing, does not affect the limb chc~ sen to perform an activity. Therefore, limb preference may be ascertained in either position. JOSPT Volume 28 Number 6 December 1998

5 3) Dynamic activity appears to be the determining factor for limb preference. The task of standing on one leg does not give adequate information of limb preference. JOSPT REFERENCES I. Annett M: The distribution of manual asymmetry. Psychology 63(3): , Augustyn C, Peters M: On the relation between footedness and handedness. Percept Mot Skills 63:lll.S-1118, Chapman )P, Chapman L), Allen 1): The measurement of foot preference. Neuropsychologia , Chibber SR, Singh I: Asymmetry in muscle weight and one-sided dominance in the human lower limbs. ) Anat 106~ , Dida DC, Nyenwe EA: breadth in children-its relationship to limb dominance and age. Ankle 8: , Gardner LP: Experimental data on the problem of motor lateral dominance in feet and hands. Psychol Rec 5:1-63, Gubbay SS: The Clumsy Child: A Study of Developmental Apraxic and Agnostic Ataxia, Philadelphia: W. B. Saunders Company, Haefner R: The relation between hand and foot tendencies of children. Pedagog Seminary 38:338, Hepper PG, Shadidullah S, White R: Handedness in the human fetus. Neumpsychologia 29(11): , Hoogmartens MI, Caubergh MA: Chewing side preference in man correlated with handedness, footedness, eyedness and earedness. Electromyogr Clin Neurophysiol27: , I. Peters M: edness: Asymmetries in foot preference and skill and neuropsychological assessment of foot movement. Psychol Bull 103: , Peters M, Durding BM: edness of left- and right-handers. Am ) Psychol 92: , Previc FH: A general theory concerning the prenatal origins of cerebral lateralization in humans. Psychol Rev 98(3): , Singh I: Functional asymmetry in the lower limbs. Acta Anat 77: , 1970 Volume 28 Number 6 December 1998 JOSFT