Downloaded from http://journals.lww.com/acsm-msse by BhDMf5ePHKbH4TTImqenVAHxkFJp/XpPk1L/H3vMGwqMxG9jwOd8eJPG+b4DlKuAX44qu/vwzmc= on 07/29/2018 Practicing a Functional Task Improves Steadiness with Hand Muscles in Older Adults ADAM R. MARMON 1 , JEFFREY R. GOULD 2 , and ROGER M. ENOKA 2 1 Department of Physical Therapy, University of Delaware, Newark, DE; and 2 Department of Integrative Physiology, University of Colorado at Boulder, Boulder, CO ABSTRACT MARMON, A. R., J. R. GOULD, and R. M. ENOKA. Practicing a Functional Task Improves Steadiness with Hand Muscles in Older Adults. Med. Sci. Sports Exerc., Vol. 43, No. 8, pp. 1531–1537, 2011. Introduction: Improvements in steadiness with practice have been associated with enhanced performance on a functional task in old adults. Purpose: The aims of the study were to examine the specificity of the association between steadiness and a functional task and to assess the influence of practicing a functional task on force steadiness of hand muscles. Methods: Twenty-three older adults (Q70 yr) participated in the study and were assigned to either a practice group (n = 15) or a control group (n = 8). Subjects completed two testing sessions that were 2 wk apart. The practice group completed six additional sessions to practice a functional task (Grooved Pegboard). Tests included maximal voluntary contractions (MVC), force steadiness (precision pinch and index finger abduction) at three target forces (5%, 15%, and 25% MVC), and the Grooved Pegboard test. The associations between strength, steadiness, and the time needed to complete the Grooved Pegboard test were examined. In addition, MVC force, steadiness, and pegboard time were compared between the two testing sessions. Results: The time needed to complete the Grooved Pegboard test was associated with index finger abduction steadiness for two of the three target forces (15% and 25% MVC) but was not associated with pinch steadiness. Practice significantly reduced the time needed to complete the Grooved Pegboard test and improved steadiness in both tasks. Conclusions: Force steadiness provides an appropriate index of hand function, especially when measured at low forces. Key Words: AGING, GROOVED PEGBOARD, PRACTICE, HAND FUNCTION S tudies on the control of movement and the changes that occur with advancing age require experimental constraints that can diminish the functional relevance of the task. One approach used to quantify changes in motor performance across the life span, for example, is to measure an individual’s ability to maintain a constant force during contractions with hand muscles (3,6,8). The force exerted by both young and old adults during these tasks is not con- stant but fluctuates about an average value. These fluctua- tions are used to denote the steadiness of a contraction and are commonly interpreted as an index of hand function. The magnitude of these fluctuations is often greater for old adults (3,4,17). Some evidence indicates that improvements in steadiness with practice are associated with enhanced performance on a functional task in old adults (7). If this association has functional significance, then improvements in a functional task (Grooved Pegboard test) with practice should also augment force steadiness. Participation in either strength or steadiness training can reduce the magnitude of the fluctuations during steady con- tractions (5,6). In addition, a recent study (11) on 75 adults (19–89 yr) found that both index finger abduction and pinch grip steadiness (contractions at 5% of maximum) were cor- related with one another (r = 0.532, P G 0.001) and with performance on the Grooved Pegboard test (r = 0.572 and r = 0.464, respectively, P G 0.001). The aim of the current study was to investigate the associations between a test of hand function (Grooved Pegboard test) and two measures of hand steadiness (index finger abduction and precision pinch) across a range of target forces (5%, 15%, and 25% of maximum) and the influence of practicing the functional task on steadiness. METHODS Twenty-three old adults (75.0 T 4.4 yr, range = 71–84 yr; 12 women) participated in this study after informed consent was obtained. All subjects were right-handed (Edinburgh Handedness Inventory) (12), free of neurological disease, and were not taking any medications known to influence neuromuscular function. In addition, none of the subjects reported engaging in activities that required extensive use of the hands for fine motor control. Subjects were assigned to Address for correspondence: Adam R. Marmon, Ph.D., 301 McKinley Lab, Department of Physical Therapy, University of Delaware, Newark, DE 19711; E-mail: marmon@udel.edu. Submitted for publication September 2010. Accepted for publication January 2011. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.acsm-msse.org). 0195-9131/11/4308-1531/0 MEDICINE & SCIENCE IN SPORTS & EXERCISE Ò Copyright Ó 2011 by the American College of Sports Medicine DOI: 10.1249/MSS.0b013e3182100439 1531 APPLIED SCIENCES Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.