Brisk Walking Speed in Older Adults Who Walk for Exercise

Effects of Tai Chi on executive function, single-leg dynamic balance, and brain functional connectivity in older adults

Although previous studies have confirmed the beneficial effects of Tai Chi Chuan (TCC) on improving balance ability and cognitive function in older adults, the synergistic regulatory mechanisms of TCC on bilateral lower limb muscle activation symmetry, brain functional connectivity(FC) strength, and dynamic balance ability remain unclear. This study aims to investigate the effects of a 9-week TCC training program on the executive function (EF), bilateral lower limb muscle activation symmetry, single-leg dynamic balance ability, and brain FC strength in elderly individuals. It provides valuable new insights into a field that has not been extensively explored before. After 9-week training intervention, (1) The TCC group showed significant improvements in the Y-balance Test (YBTs), with enhanced symmetry in single-leg dynamic balance between the bilateral lower limbs and a significant reduction in the laterality of lower limb muscle activation. (2) TCC training strengthened the FC of related brain regions during YBTs. When performing YBTs with the left and right legs separately, the laterality of the average brain FC strength between the two tasks was significantly reduced. (3) During EF tasks, the reaction time was significantly reduced, and the concentration of oxygenated hemoglobin in the prefrontal cortex increased. Studies have shown that TCC has significantly superior intervention effects compared to brisk walking in improving neuromuscular function in older adults. Through its multisensory integration training model, TCC simultaneously enhances neuromuscular coordination and brain network collaboration efficiency, promoting the adaptive reorganization of dynamic balance control.

Determination of moderate walking intensity using step rate and VO2 reserve in healthy men

OBJECTIVE

This study investigated step rates (SR) during overground walking to estimate the relative aerobic capacity that corresponds to a moderate intensity.

METHODS

The present study utilized a repeated measure, within-subjects design incorporating a counterbalanced order. A total of twenty-three healthy men walked on a 119-meter oval track with artificial turf at self-selected pace (FP), 100, 120, and 140 steps/min for 6 min each while oxygen uptake (VO2), speed (in km/h), distance (in m), and steps (in steps/min) were measured.

RESULTS

During FP, participants walked an average cadence of 117 ± 9.3 steps/minclose to 120 steps/min, which corresponds to 4.7 metabolic equivalents (METs). The estimated VO2 reserve was 30.5% of VO2 reserve at the FP and was close to the 120 steps/min of 33.3%. At the 100 and 140 steps/min, the VO2 reserve were 24.1% and 45.2%, respectively. The regression analysis revealed that an SR of 88.2 elicited 3METs and 17.1% of VO2reserve. Additionally, an SR of 129 elicited 5.9METs and 40% of VO2 reserve.

CONCLUSIONS

This study demonstrated that a moderate walking intensity for young, healthy men corresponded to 128.9 steps per minute. A range of 120 ~ 140 steps/min for walking could be recommended as a general guideline for moderate-intensity exercise. However, concerning providing public guidelines, caution should be taken regarding determining the moderate walking intensity due to the individual's fitness level.

Differences in muscle coordination between older men and women during brisk walking

Brisk walking is a highly recommended physical activity for healthy community-dwelling older adults. The objective of this study was to examine through principal component analysis (PCA) how muscle coordination differs between older women and men during brisk walking. Thirty-five healthy older adults (65.2 ± 3.0 years old, 18 females, and 17 males) participated in the study. Eight surface electromyographic electrodes were used to record lower extremity muscle activities, and four inertial measurement unit sensors to monitor hip, knee, and ankle motion. Energy expenditure and heart rate were also measured during brisk walking. The effects of a person's sex on muscle coordination were identified through wavelet and PCA analysis of the sEMG signals. The results of energy expenditure and heart rate confirmed that brisk walking exercise is beneficial for older adults. PCA analysis showed that muscle coordination patterns differ between older women and men: during the stance phase a greater co-contraction of tibialis anterior and soleus in the men, and a greater activation of the quadriceps muscles during the loading-response phase in the women. The wavelet and PCA analyses facilitated a quantitative appraisal of sex-specific differences in the muscle coordination patterns of older men and women during brisk walking.

Classification of moderate-intensity overground walking speed in 21- to 85-year-old adults

The Compendium of Physical Activities reports that walking at 2.5 mph associates with absolutely-defined moderate intensity (i.e., ≥3 metabolic equivalents [METs]). However, it is unclear whether this speed threshold is accurate during overground walking and/or across the adult age-span. This study aimed to identify optimal and heuristic speed thresholds associated with 3 METs during overground walking across age groups. Healthy adults (n = 248, 21-85 years old, 49% women) performed a 5-minute self-paced overground walking trial. Speed was measured using an electronic gait mat, and oxygen uptake was measured using indirect calorimetry and converted to METs. Optimal and heuristic thresholds and classification accuracy metrics were determined and compared using ROC curve analyses. Speed thresholds (95% CIs) associated with 3 METs for the whole sample, young (21-40 years), middle-aged (41-60 years) and older-aged (61-85 years) groups were 1.29 (1.25, 1.33), 1.30 (1,26, 1,35), and 1.25 (1.21, 1.29) m/s, respectively. Overall, 3 mph and 5 km/h performed better than 2.5 mph and 4.5 km/h in balancing both sensitivity and specificity (higher Youden's Indices). Overground walking speeds associated with 3 METs were similar across age groups. A heuristic threshold of 3 mph or 5 km/h may better identify absolutely-defined moderate intensity overground walking.

Music Tempo: A Tool for Regulating Walking Cadence and Physical Activity Intensity in Overweight Adults?

This study investigated if music tempo can prompt a desired walking cadence, and if music can provide a stimulus to regulate physical activity intensity in a longitudinal physical activity intervention with free-living adults. Overweight adults (n = 37; 94.26 ± 17.11 kg; 49.63 ± 12.37 years) were randomly assigned to an intervention (IG, n = 17) or usual care group (UC, n = 20) as part of a novel nine-month walking intervention. IG participants walked to self-selected music with a predetermined tempo and received a behavioural change support programme. At baseline, four-, six- and nine-months participants were asked to walk around an elliptical track at their habitual pace (0-2 min) and then in time to a predetermined tempo (2-8 min) designed to elicit moderate intensity. Cadence response (steps/min) was assessed and intensity (heart rate (bpm) recorded using wireless telemetry. A repeated measures general linear model (GLM) examined differences between groups over time (p < 0.05). All data is presented as means ± SD. At each assessment point both groups displayed an immediate cadence adjustment in response to music tempo (p < 0.01) i.e., habitual cadence vs. 3 METs target cadence (p < 0.05) and 3 METs target cadence vs. 5 METs target cadence (p < 0.05). Additionally, IG participants displayed an increased habitual cadence (0-2 min) at each assessment point (p < 0.05; 110 ± 9, 121.80 ± 7.5, 121.46 ± 10, 121.93 ± 7 steps/min respectively). UC participant's habitual cadence was unchanged from 0-9 months (p > 0.05; 120 ± 10, 116 ± 13, 119 ± 12 and 119 ± 9 steps/min respectively). Music tempo may be a useful regulatory tool to prompt the free-living individual to reach an appropriate stride rate to achieve a walking pace that is at least moderate intensity. It also appears that results may be trainable as throughout the study an increased habitual walking cadence was observed, in the absence of music.

Outdoor Walking Speeds of Apparently Healthy Adults: A Systematic Review and Meta-analysis

BACKGROUND

Walking outdoors can be used by many individuals to meet public health guidelines for moderate-to-vigorous-intensity physical activity. The speed at which adults walk may be a proxy for intensity. Traditional estimates of indoor walking speed are unlikely to reflect self-selected usual or other instructed paces of outdoor walking speed.

OBJECTIVE

To inform estimates of pace-based walking speed of apparently healthy adults in outdoor settings.

METHODS

We searched four electronic databases for articles published in English between January 1970 and March 2019. Studies that reported walking speed (m/s), cadence (steps/min), or intensity (mL/kg/min) of ambulatory, apparently healthy, and community-dwelling adults (> 18 years) were included. Walking speed categories were defined according to the description provided in each study. Meta-analysis was used to synthesise speed, cadence, and intensity data by slow, usual, medium, fast, and maximal pace (where reported).

RESULTS

Thirty-five studies, representing 14,015 participants (6808 women, 5135 men, and 2072 sex not specified), were identified. The mean (95% CI) walking speed for slow, usual, medium, fast, and maximal pace was 0.82 (0.77-0.86), 1.31 (1.27-1.35), 1.47 (1.44-1.49), 1.72 (1.64-1.81), and 1.62 (1.45-1.79) m/s, respectively. Mean cadence (95% CI) for usual and fast paces were 116.65 (114.95-118.35) and 126.75 (121.87-131.63) steps/min, respectively. The mean oxygen consumption (95% CI) for the usual and medium paces was 11.97 (11.69-12.25) and 13.34 (12.94-13.73) mL/kg/min, respectively.

CONCLUSION

These findings provide greater clarity with regard to how various indicators of enacted walking pace, speed, and intensity overlap and how each can be best communicated in the real-world setting to optimise health-related outcomes. Pace-based instructions can be used to support walking in outdoor settings within public health guidelines.

A validation study of the use of smartphones and wrist-worn ActiGraphs to measure physical activity at different levels of intensity and step rates in older people

BACKGROUND

Physical activity promotes healthy ageing in older people. Accurate measurement of physical activity in free-living environment is important in evaluating physical activity interventions.

RESEARCH QUESTION

What is the criterion validity of 1)an ActiGraph to identify physical activity at different intensity levels and 2)an ActiGraph and a smartphone to measure step rate?

METHODS

Community-dwelling older people aged≥60 were recruited. The index tests were using ActiGraph worn in different positions (i.e.,both wrists and hip) to measure physical activity intensity and step rate and using smartphone (i.e., Samsung J2 pro and Google Fit) worn in different positions (i.e.,trousers pocket and waist pouch) to measure the step rate. The reference standards were using indirect calorimetry (i.e.,CosMedK4b 2) to measure physical activity intensity and using direct observation for step rate. Subjects were exposed in different physical activity intensity levels (i.e.,sedentary:MET < 1.5,light: MET = 1.5-2.99, moderate:MET = 3.0-6.0, vigorous:MET>6) and step rates through walking on a treadmill at different speeds (i.e.,2-8 km) for approximately 30 min. Spearman's rho, ROC analysis, and percentage error were employed to report the criterion validity.

RESULTS

31 participants completed the tests. ActiGraphs worn in different body positions could significantly differentiate physical activity intensity at the levels of "light- or-above" (VM cut-off = 279.5-1959.1,AUC = 0.932-0.954), "moderate-or-above" (VM cut- off = 1051.0-4212.9,AUC = 0.918-0.932), and "vigorous" (VM cut-off = 3335.4-5093.0, AUC = 0.890-0.907) well with different cut-off points identified. The step rate measured by direct observation correlated significantly with ActiGraph and smartphone (rho = 0.415-0.791). Both ActiGraph and smartphone at different positions generally underestimated the step rate (%error= -20.5,-30.3).

SIGNIFICANCE

A wrist-worn ActiGraph can accurately identify different physical activity intensity levels in older people, but lower cut-off points in older people should be adopted. To measure step rate, a hip-mounted ActiGraph is preferable than a wrist- worn one. A smartphone employing Google Fit generally underestimates step rate but it gives a relatively more accurate estimation of step rate when the older people walk at a speed of 4-8 km/h.

Using accelerometry to classify physical activity intensity in older adults: What is the optimal wear-site?

Abstract This study aimed to determine the optimal accelerometer wear-site specific cut-points for discrimination of the sedentary time, light physical activity and moderate-to-vigorous physical activity (MVPA) in older adults. Twenty-three adults (14 females) aged 55-77 years wore a GENEActiv accelerometer on their non-dominant wrist, dominant wrist, waist and dominant ankle whilst undertaking eight, five-minute bouts of activity: lay supine, seated reading, slow walking, medium walking, fast walking, folding laundry, sweeping and stationary cycling. VO₂ was assessed concurrently using indirect calorimetry. Receiver-operating-characteristic (ROC) analyses were used to derive wear-site specific cut-points for classifying intensity. Indirect calorimetry indicated that being lay supine and seated reading were classified as sedentary (<1.5 METs), laundry as light (1.51-2.99 METs) and sweeping, slow, medium and fast walking and cycling all classified as moderate intensity (>3 METs). Areas under ROC curves indicated that the classification of sedentary activity was good for the non-dominant wrist and excellent for all other wear sites. Classification of MVPA was excellent for the waist and ankle, good for the waist and poor for the dominant and non-dominant wrists. Overall, the ankle location performed better than in other locations. Ankle-worn accelerometry appears to provide the most suitable wear-site to discriminate between sedentary time and MVPA in older adults.

Where to locate transit stops: Cross-intersection profiles of ultrafine particles and implications for pedestrian exposure

Epidemiological studies have shown that exposure to traffic-related pollutants increases incidence of adverse health outcomes. Transit users in cities across the globe commonly spend 15-45 min or more waiting at transit stops each day, often at locations with high levels of pollution from traffic. Here, we investigate the characteristics of concentration profiles of ultrafine particles (UFP) with 5 m spatial resolution across intersections, to determine the best place to site transit stops to minimize exposures. Cross-intersection UFP profiles were derived from 1744 profiles covering 90 m before and after each intersection center with a mobile monitoring platform. Measurements were made at 10 signalized intersections located at six urban sites, each with a distinct built environment, during both mornings and afternoons. Measurements were made within 1.5 m of the sidewalk and approximately at breathing height (1.5 m above ground level) to approximate sidewalk exposures. UFP profiles were strongly influenced by high emissions from vehicle stops and accelerations, and peaked within 30 m of intersection centers; from there concentrations decreased sharply with distance. Peak concentrations averaged about 90% higher than the minima along the block. They were accompanied by more frequent and larger transient concentration spikes, increasing the chance of people near the intersection being exposed to both short-term extremely high concentration spikes and higher average concentrations. The decays are somewhat larger before the intersection than after the intersection, however as siting transit stops after intersections is preferred for smooth traffic flow, we focus on after the intersection. Simple time-duration exposure calculations combined with breathing rates suggest moving a bus stop from 20 to 40-50 m after the intersection can reduce transit-users' exposure levels to total UFP substantially, in proportion to the reciprocal of the magnitude of elevation at the intersection.

Coincidence Anticipation Timing Performance during an Acute Bout of Brisk Walking in Older Adults: Effect of Stimulus Speed

This study examined coincidence anticipation timing (CAT) performance at slow and fast stimulus speeds before, during, and after an acute bout of walking in adults aged 60–76 years. Results from a series of repeated measures ANOVAs indicated significant rest versus exercise × stimulus speed × time interactions for absolute and variable errors (both P = 0.0001) whereby absolute and variable error scores, when stimulus speed was slow, improved as the duration of exercise increased. When stimulus speed was fast there were significantly greater absolute and variable errors at 18 minutes of the walking bout. There was also greater error at 18 minutes during walking compared to rest. These results suggest that, in a task involving walking and CAT, stimulus speeds plays an important role; specifically walking (exercise) enhances CAT performance at slow stimulus speeds but reduces CAT performance at fast stimulus speeds. The implications are that in everyday situations, where events require dual-task responses to be made at different speeds, for example, walking on the pavement whilst avoiding a crowd, compared to crossing a busy road, an understanding of how different stimulus speeds influence dual-task performance is extremely important, particularly in the older adult population.

Physical Activity and Depressive Symptoms Interact to Predict Executive Functioning Among Community-Dwelling Older Adults

BACKGROUND/STUDY CONTEXT

Physical activity is beneficial for the executive functioning (EF) of older adults, but may be particularly protective of EF when they are cognitively vulnerable, such as during depressive episodes. Intervention studies support more potent effects of physical activity on EF among clinically depressed older adults, although these results may have limited generalizability to the daily mood and physical activity of healthy, community-dwelling older adults.

METHODS

The current study aimed to test whether physical activity among older adults was more protective of EF during periods of cognitive vulnerability due to mildly elevated depressive symptoms. Longitudinal data from 150 generally healthy, community-dwelling older adults were collected semiannually and analyzed with multilevel modeling.

RESULTS

Physical activity was more protective of EF within individuals during periods of relatively elevated depressive symptoms.

CONCLUSIONS

The power of physical activity to protect EF during periods of cognitive vulnerability may extend to community-dwelling older adults with nonclinical levels of depressive symptoms.

Evaluation of inactive adults' ability to maintain a moderate-intensity walking pace

OBJECTIVES

To determine self-selected brisk walking pace in currently inactive adults and investigate the efficacy of rhythmic auditory stimuli to regulate moderate intensity walking.

DESIGN

A single-sample controlled laboratory design.

METHODS

Currently inactive adults (N=25; 76% female; age=34±13yr) completed a moderate intensity treadmill walking trial, during which cadence and steady-state O2 were measured. Participants then completed a 10-min self-paced "brisk" walk followed by a 10-min moderate-paced walk, prompted by a clip-on metronome matched to the treadmill cadence. Data were analyzed using RM t-test, Cohen's d, Bland-Altman plot, and one-way RM ANOVA.

RESULTS

Mean energy expenditure and cadence during the treadmill trial were 3.88±0.53METs and 114±8stepsmin(-1). During self-paced brisk walking cadence was 124±8stepsmin(-1). Cadence during metronome-paced walking was slower for all participants (114±8stepsmin(-1); p<0.05, d=1.23). From the Bland-Altman plots, 23 participants walked within ±3stepsmin(-1) of the metronome cadence, and the other 2 participants were within ±10stepsmin(-1). There were no significant differences (p>0.05) among the minute-by-minute cadences across the 10min of either condition.

CONCLUSIONS

Energy expenditure during 2.7mph treadmill walking was higher than 3 METs. Inactive adults walk at a higher cadence during "brisk" walking, compared to walking at a metronome-guided moderate pace. While the natural walking pace of inactive adults was at an intensity known to produce health benefits, and was maintained for 10min, the use of rhythmic auditory feedback is an effective method for regulating walking at a prescribed intensity in inactive adults.

Can we teach moderate intensity activity? Adult perception of moderate intensity walking

OBJECTIVES

To investigate how people determine the intensity of their physical activity, respond to instruction, and their understanding of moderate intensity walking.

DESIGN

Experimental.

METHODS

Forty nine regular walkers had their walking speed, heart rate and rate of perceived exertion measured during their normal walking behaviour, when instructed to walk at a moderate intensity, and after provision of feedback on how to meet moderate intensity walking.

RESULTS

Although moderate intensity walking was generally perceived as too low to be beneficial, walking speed was the best variable matched across all experiments for moderate intensity (83.7%, 67.3% and 93.9%), followed by heart rate, with a large proportion of participants responding favourably to instruction relating to heart rate and speed to meet moderate intensity walking. Rate of perceived exertion was a poor reflector of walking intensity.

CONCLUSION

Most participants naturally selected a walking intensity that elicits moderate intensity and when instructed to walk at moderate intensity, the intensity is more vigorous. Attempting to match speed and heart rate limits for moderate intensity reduced the intensity perceived by participants.

The effects of respiratory-muscle training on exercise in older women

This research examined the effects of respiratory-muscle (RM) training on RM function and exercise performance in older women. Twenty-six women (60-69 yr of age) were assessed for spirometry, RM strength (maximal inspiratory and expiratory pressure), inspiratory-muscle endurance, and walking performance to a perceived exertion rating of "hard." They were randomly allocated to a threshold RM training group (RMT) or a nonexercising control group (CON) for 8 wk.After training, the 22% (inspiratory) and 30% (expiratory) improvements in RM strength in the RMT group were significantly higher than in the CON group (p < .05). The RMT group also displayed several significant performance improvements, including improved within-group treadmill performance time (12%) and reductions in submaximal heart rate (5%), percentage of maximum voluntary ventilation (16%), and perceived exertion for breathing (8%). RM training appears to improve RM function in older women. Furthermore, these improvements appear to be related to improved submaximal exercise performance.

Activity-monitor accuracy in measuring step number and cadence in community-dwelling older adults

The primary purpose of this study was to investigate the accuracy of the activPAL physical activity monitor in measuring step number and cadence in older adults. Two pedometers (New-Lifestyles Digi-Walker SW-200 and New-Lifestyles NL2000) used in clinical practice to count steps were simultaneously evaluated. Observation was the criterion measure. Twenty-one participants (65-87 yr old) recruited from community-based exercise classes walked on a treadmill at 5 speeds (0.67, 0.90, 1.12, 1.33, and 1.56 m/s) and outdoors at 3 self-selected speeds (slow, normal, and fast). The absolute percentage error of the activPAL was <1% for all treadmill and outdoor conditions for measuring steps and cadence. With the exception of the slowest treadmill speed, the NL-2000 error was <2%. The SW-200 was the least accurate device, particularly at slower walking speeds. The activPAL monitor accurately recorded step number and cadence. Combined with its ability to identify primary postures, the activPAL might be a useful and versatile device for measuring activity in older adults.

Improvements in walking speed experienced by elders participating in a cardiovascular exercise program

PURPOSE

The purpose of this retrospective investigation was to determine: (1) whether a cardiovascular exercise program was capable of improving treadmill gait speed of elderly individuals, and (2) if such an improvement was associated with specific determinants.

METHODS

Twenty residents of a retirement community were assessed at baseline and followed up after approximately 1 year (mean=10.7 +/- 1.1 months) of participation in a prescribed cardiovascular exercise program. On each individual's initial visit, self-regulated walking time for one-quarter mile on a Star Trac 4500 motorized treadmill with no incline was recorded. Individuals were then placed on a cardiovascular exercise program that emphasized walking, which they performed 3 to 5 sessions/week for 20 to 30 minutes/session. At follow-up, individuals repeated the one quarter-mile treadmill walk, and times were compared to those obtained on the initial visit.

RESULTS

Mean walking treadmill times decreased significantly (p < 0.05) from 7.7 +/- 2.7 minutes to 5.7 +/- 2.1 minutes, with both male and female participants showing similar changes. Baseline walk time and change in walk time at follow-up were highly correlated (r = .682/p < .0001), but participants with slower baseline walk times showed the greatest gains. Participant age was also correlated to change in walk time (r = .389/p = .045).

CONCLUSION

All program participants showed some degree of improvement in walking speed, suggesting that benefits may be applicable to a wide range of elderly groups. However, individuals with the slowest baseline walk times demonstrated the greatest improvement.

Effect of Free-Living Daily Physical Activity on Salivary Secretory IgA in Elderly

PURPOSE

The aim of this work was to assess the relationship in elderly subjects between free-living daily physical activity and mucosal immunity, especially salivary secretory immunoglobulin A (SIgA).

METHODS

Elderly volunteers (114 men and 170 women) aged 71.3 +/- 0.3 yr (range: 65-86 yr) participated in this study. Resting saliva samples were collected in the morning. Saliva samples stimulated by chewing a sterile cotton ball at a frequency of 60/60 s were collected. The SIgA concentration was measured using enzyme-linked immunosorbent assay (ELISA), and the SIgA secretion rate was calculated. Free-living step count (steps per day), energy expenditure (kJ x kg(-1) x d(-1)), and activity durations (min x d(-1)) at specific intensity levels (inactive, light, moderate, and vigorous) were evaluated using an electric pedometer. The data obtained were stratified by pedometer-determined steps per day using quartiles (Q1-Q4) for distribution.

RESULTS

Elderly in quartiles showed step counts of 2962 +/- 94, 5118 +/- 62, 6832 +/- 59, and 9951 +/- 264 steps per day. Significant differences were found in the mean step count (P<0.0001), energy expenditure (P<0.0001), and activity duration (P<0.0001) with increasing pedometer-determined activity quartiles. Both SIgA concentration and SIgA-secretion rate were significantly higher for Q3 than for Q1 (P<0.05). Meanwhile, saliva flow rates showed no significant differences across quartiles.

CONCLUSION

These results suggest that a free-living daily physical activity level of approximately 7000 steps per day might be regarded as a moderate daily physical activity target for elderly people to improve mucosal immune function.

Evaluation of quality of commercial pedometers

BACKGROUND

The purpose of this study was to: 1) evaluate the quality of promotional pedometers widely distributed through cereal boxes at the time of the 2004 Canada on the Move campaign; and 2) establish a battery of testing protocols to provide direction for future consensus on industry standards for pedometer quality.

METHODS

Fifteen Kellogg's* Special K* Step Counters (K pedometers or K; manufactured for Kellogg Canada by Sasco, Inc.) and 9 Yamax pedometers (Yamax; Yamax Corporation, Tokyo, Japan) were tested with 9 participants accordingly: 1) 20 Step Test; 2) treadmill at 80m x min(-1) (3 miles x hr(-1)) and motor vehicle controlled conditions; and 3) 24-hour free-living conditions against an accelerometer criterion.

RESULTS

Fifty-three percent of the K pedometers passed the 20 Step Test compared to 100% of the Yamax. Mean absolute percent error for the K during treadmill walking was 24.2+/-33.9 vs. 3.9+/-6.6% for the Yamax. The K detected 5.7-fold more non-steps compared to the Yamax during the motor vehicle condition. In the free-living condition, mean absolute percent error relative to the ActiGraph was 44.9+/-34.5% for the K vs. 19.5+/-21.2% for the Yamax.

CONCLUSIONS

K pedometers are unacceptably inaccurate. We suggest that research grade pedometers: 1) be manufactured to a sensitivity threshold of 0.35 Gs; 2) detect +/-1 step error on the 20 Step Test (i.e., within 5%); 3) detect +/-1% error most of the time during treadmill walking at 80m x min(-1) (3 miles x hr(-1)); as well as, 4) detect steps/day within 10% of the ActiGraph at least 60% of the time, or be within 10% of the Yamax under free-living conditions.

Can self-reported preference for exercise intensity predict physiologically defined self-selected exercise intensity?

Exercise prescription guidelines emphasize the importance of individual preferences for different intensities, but such preferences have not been studied systematically. This study examined the hypothesis that the preference scale of the Preference for and Tolerance of the Intensity of Exercise Questionnaire would predict self-selected exercise intensity. Twenty-three previously sedentary middle-aged women participated in a treadmill test and a 20-min session at a self-selected intensity. After controlling for age, body mass index, and peak oxygen uptake, the preference scale accounted for significant portions of the variance in the percentage of oxygen uptake associated with the ventilatory threshold at Minute 15 and Minute 20 of the session at self-selected intensity.

Responses to Walking-Speed Instructions: Implications for Health Promotion for Older Adults

This study examined the effect of age on descriptive walking-speed instructions commonly used in health promotion. Participants were 9 young (20–23 years) and 9 older (75–83 years) women. Oxygen uptake and walking speed were measured in response to descriptive walking instructions (“slow,” “comfortable,” “brisk,” and “fast”). Although the older women walked ≈20% slower in response to all walking instructions and with significantly lower oxygen costs for brisk and fast, the intensity of the exercise represented a much greater percentage of VO2max and showed greater interindividual variation. When asked to walk at a brisk pace, the older women averaged 67% VO2max (SD 20.6), whereas the young women averaged only 45% VO2max (SD 4.5). With older people, brisk might elicit an exercise intensity unnecessarily high for physiological benefit and that might compromise safety and adherence, which emphasizes the need for validation of carefully worded exercise and training guidance for older adults.