Perceptual and Motor Skills, 1990, 71, 131-140. O Perceptual and Motor Skills 1990

EFFECTS OF WALKING O N REACTION AND MOVEMENT TIMES AMONG ELDERS BEVERLY L. ROBERTS

Case Western Reserve Unjversio Summary.-The purpose of this study was to examine the effects of a 6-wk. walking program on reaction times and movement times among 52 elders. Twenty-seven elderly, whose mean age was 71.8 yr. comprised the experimental group, and 25 elderly whose mean age was 71.8 yr. comprised the comparison group. The former subjects walked for 30 min. three times a week for 6 wk. while the latter maintained their normal activity. No significant differences in simple or choice reaction times and the associated movement times were found. To clarify the relationship of health and current and past physical activity, correlations of these with both simple and choice reaction times and movement times were examined. Except for the number of miles walked in a week, none of the correlations were significant. These results may not support previous findings that reaction and movement times were shorter with life-long participation in aerobic activity. However, the present study examined persons who were sedentary and were not involved in a life-long participation in aerobic exercise. Implications of these findings are discussed.

The purpose of this study was to examine the effect of an aerobic activity, walking, on reaction times and movement times of elders. Shortened reaction and movement times among elderly adults has been associated with aerobic exercise. In previous studies the reaction times of adults who had been involved in high intensity aerobic exercise all their life were compared to persons sedentary most of their life. Sherwood and Selder (1979) compared 32 runners who averaged 42 miles per week to 32 sedentary persons and found that reaction times were significantly shorter among the runners. Investigators also found that reaction times were significantly shorter among both elderly and young adults involved in a regular program of life long high-intensity aerobic exercise than the sedentary young (Botwinick & Thompson, 1968; Spirduso, 1975; Spirduso & Clifford, 1978). These results suggest that aerobic exercise at high intensity may shorten reaction time among the elderly. Evidence about the effect of aerobic exercise on movement times is more ambiguous. Clarkson (1978) studied movement time during a patellar reflex and found no significant difference in this time between active and sedentary persons, regardless of age. Other investigators found significant differences in movement times between activity level in both young and 'The preparation of this manuscript was supported in part by a grant from Sigma Theta Tau, P p h a Mu Chapter and F.P.B. School of Nursing Alumni Association. Address correspondence to B. L. Roberts, Ph.D., Frances Payne Bolton School of Nursing, Case Western Reserve University, 2121 Abington Road, Cleveland, OH 44106.

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elderly persons (Spirduso, 1975; Spirduso & Clifford, 1978). However, the latter investigators did not use spinal reflex activity as Clarkson (1978) did; they used a complex response initiated in the cerebral cortex that required a specific action. The inconsistency in these results may be due to differences in the methods of measuring movement time. Factors other than aerobic activity may have accounted for the shorter reaction and movement times found among persons with a lifetime involvement in aerobic exercise. These include health status and genetically determined physical abilities that influence the propensity of individuals to participate in aerobic exercise. These factors may have accounted for some of the differences found between sedentary persons and those actively engaging in aerobic exercise. Abraham and Birren's (1973) findings that persons with longer reaction times were predisposed to coronary heart disease provides some support that disease also influences reaction time. The purpose of this study was to examine (1) the relationship of health status and participation in aerobic activity to reaction times and movement times and (2) the effects of a 6-wk. walking program on these times among sedentary elderly. A walking program was chosen because it is an aerobic activity amenable to adjustments in aerobic intensity and is also appealing to the majority of elders. Since the effects of aging adversely affect the function of the musculoskeletal system and increase the risk of injury to this system, walking was chosen because it places less stress on aging - muscles, bones and joints than high impact aerobic exercises, such as running or jogging. Thus, walking is a safe and appealing exercise for elderly adults.

Sample A nonprobabihty sampling plan was used to recruit 61 persons aged 65 yr. of older, ranging in age from 65 to 87 yr., from seven senior citizens centers. Given the difficulty encountered in recruiting elders into a study with random assignment to the walking program, subjects were recruited specifically for the experimenral or comparison group. Medical histories and review of current medications were used to identify current and past medical problems. To control the confounding effects of diseases of the nervous and muscular systems on reaction and movement times, elderly who had neurological and muscular diseases were excluded. To ensure the safety of elders in the walking program, those with seriously impaired gait were also excluded. Since heart rate was used to adjust the aerobic intensity of walking, elders taking beta-blockers and other antbarrhythmic drugs with side effects of bradycardia or tachycardia also were excluded. Thirty-one elders obtained approval from their physician to participate in the w a k n g program. The mean age of this group was 71.8 yr. (SD = 1.3)

ELDERS' WALKING AND REACTION TIMES

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and consisted of 5 (16.1%) men and 26 (83.9%) women. Thirty elders were recruited for the comparison group that consisted of 4 (13.3%) men and 26 (86.7%) women, with a mean age of 71.8 yr. (SD= 1.4). The two groups did not differ significantly in current and past medical problems or in medication taken.

Instruments and Measurements Subjects rated their perceived health status on a 5-point Likert scale ranging from very poor to excellent. Tissue (1972) and Fillenbaum (1979) demonstrated that perception of health was significantly related to number of diseases and functional capacity. Maddox and Douglass (1973) found that this perception was significantly related to a number of diseases and functional capacity. Maddox and Douglass (1973) found that this perception was significantly related to physicians' ratings of health. Consequently, the rating of perceived health status has criterion validity. Several indices were developed to quantify past and present participation in aerobic activity. First, an index of present activity was the total number of aerobic activities in which a subject participated at least 30 min. in an average week. Second, self-report of the number of miles usualy walked in one week was used. To estimate participation in aerobic activities during their lifetime, an index of past aerobic activity was developed. This score was the sum of weekly aerobic activities lasting at least 30 min. multiplied by the number of years of participation. This score was summed across activities for an index of past aerobic activity. Although these indices are subject to the artifacts of self-reporting, they were admitted as representative estimates of aerobic activity for thls sample. No estimates of the reliability of these indices were attempted at this time. Reaction time and movement time were measured using the protocols of Botwinick and Thompson (1968) and Spirduso (1975). Subjects sat at a display board consisting of a warning light, three lights, switches below each light except the warning light and a switch at the base of the board (ready switch). Since preparatory information about the beginning of a testing sequence shortens reaction times (Loveless, 1979), the warning light signaled the beginning of each trial. One to 6 sec. after the onset of the warning light, the onset of three other lights was randomized. A computer controlled the sequence of onset and computed reaction times and movement times. Two types of reaction time (RT) were measured, simple reaction time and choice reaction time. Prior to the trial for simple RT, the subject was told w h c h of three lights would be onset, while for the choice RT the subject was not told which light would be onset. The subject placed an index finger of the dominant hand on the ready switch. When one of the three lights was turned on, the subject removed the index finger from the ready switch and depressed the switch under the light that was on. Simple and

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choice R T were expressed as the time in milliseconds from the onset of the light stimulus to the release of the ready button. Movement times for simple and choice R T were the times in milliseconds from the release of the ready button to the depression of the button under the lit light. There were 30 trials for simple and choice R T and their associated movement times giving a total of 60 trials. Simple R T and related movement time were measured first. After a 2-rnin. rest, choice R T and related movement time were measured. Less than 1% of trials for choice R T o n which an incorrect response occurred were replaced by another trial. Since learning is a confounding factor in the measurement of reaction and movement times (Abrahams & Birren, 1973; Sherwood & Selder, 1979)) a random sample of 10 subjects was selected and means for each trial computed. These means were plotted against trials. Learning was considered to end at the point where the curve flattened out. At pretest and posttest, this occurred at Trial 12 for both groups and for all reaction and movement times. The subsequent 18 trials were averaged to obtain a score for simple RT, choice RT and associated movement times. Protocol for Walking Previous investigations have found significant changes in psychomotor performance with duration of aerobic exercise from 6 wk. (Roberts, 1989) to 12 wk. (Blumenthal, Emery, Madden, George, Coleman, Riddle, McKee, Reasoner, & Williams, 1989; Posner, Gorman, Klein, & Woldow, 1986). I t was expected that a 6-wk. aerobic exercise program would be long enough to improve reaction and movement times. Experimental subjects walked 30 min. three times a week for 6 wk. The age-adjusted heart rate was used to set the aerobic intensity of walking. Specifically, subjects walked at a pace that elevated heart rate to 60% to 70% of their age-adjusted maximum heart rate (220 - age). Since cessation of walking is accompanied by a reduction in heart rate, the radial artery was palpated for 10 sec. while the subject momentarily stopped walking, and thls rate was multiplied by 6 for a 1-rnin. rate. Heart rate was measured at 5 , 10 and 25 min. of walking. The pace of walking differed across individuals, but the aerobic intensity of that pace, as reflected in heart-rate, was the same for all subjects. A registered nurse monitored the heart rate response to walking and also monitored subjects for untoward effects. For a more complete description of the walking program refer to Roberts (1989). Data Collection After obtaining written consent, measurements were made of reaction times and movement times. Baseline data regarding perceived health, health problems, hospitalizations, medications, blood pressure, pulse, past and present participation in aerobic activity and walking were recorded. After

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pretesting, the experimental group participated in the 6-wk. walking program, while the comparison group maintained their usual activities. Six weeks later, posttest measurements were made. Subjects in both groups maintained a log of aerobic activities and duration of participation for the 6 wk. between testings. Twenty-five subjects in the comparison group completed the study. Given travel and conflicting activities, three women and two men were lost to posttest. Twenty-seven subjects completed the walking program. They attended a mean of 12.6 (SD = 3.8) sessions, and the number of miles walked per session increased from .9 miles in the first week to 1.9 miles in the sixth week. Two subjects in the experimental group did not complete posttesting: one man because of thrombophlebitis and one woman because of a death in the family. Two subjects were dropped from subsequent analyses because they attended only two of the walking sessions. Since a nonprobability sample was used, differences at pretesting between the experimental and comparison groups were examined. These groups were not significantly different in health status, current and past medical problems, current medications or index of past and present aerobic activity or miles walked in a week. The daily logs showed that subjects in both groups were not involved in other exercise programs or in regular strenuous activity. See Table 1 for means and standard deviations on each of the five variables for both groups. TABLE 1

MEANSA N D STANDARD DEVIATIONS OF HEALTH, NUMBER OF DISEASES, MILES WNKU), AND INDEXES OF PRESENT AND PASTAEROBIC ACTIVITY (n = 27) AND COMPARISON (n = 25) GROUPS FOREXPERIMENTAL Variable Perceived Health Number of Diseases Past Activity Present Activity Miles Walked

Experimental Group

Comparison Group

M

SD

M

SD

4.18 1.45 10.84 0.45 3.80

0.68 1.00 25.27 1.70 7.04

3.87 1.32 12.97 0.97 2.99

0.62 0.87 23.92 2.17 6.20

Using the method described by Pearson and Hartley (cited by Dixon, 1985), it was noted that all reaction times and movement times, at both pretest and posttest, were significantly different from a normal distribution. Consequently, all these times were transformed using the reciprocal to meet the assumptions of subsequent statistical tests. To examine the relationship of physical activity and health status to reaction and movement times, correlations of these times with indices of

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present and past aerobic acrivity were computed using data from pretesting; see Table 2 for correlations. Only simple and choice movement times were significantly correlated with the index of past aerobic activity but not in the anticipated direction (rs = .26 and .27, respectively). That is, these reaction times increased as the index of past activity increased. None of the reaction and movement times were significantly correlated with the index of present activity. However, choice RT was significantly shorter among those who walked a greater number of miles in a week ( r = -.34). Only simple and choice movement times were significantly correlated with perceived health but, again, not in the anticipated direction (rs = .26 and .29, respectively). That is, these movement times increased as health status increased. Further, the number of diseases was not significantly correlated with any of the times. TABLE 2 CORRELATIONS BETWEEN REACTION A N D MOVEMENT T ~ E WITH S HEALTH,DISEASE, INDEXES OF PRESENT AND PASTAEROBIC A C T M ~ AND S DISTANCE WALKEDm A WEEK Variable Health Disease Aerobic Activity Present Past Miles Walked

Reaction time Simple Choice

< .01

Movement Time Simple Choice

.05

.09 -.04

.25* -.06

.27* -.06

.07 .08 -.20

.01 .05 -.31t

.01 .26* -. 17

.17 .29" -.I2

Note.-Based on pretest data with both groups combined, n = 61. *p

Effects of walking on reaction and movement times among elders.

The purpose of this study was to examine the effects of a 6-wk. walking program on reaction times and movement times among 52 elders. Twenty-seven eld...
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