Minsoo Kang

Revisiting "how many steps are enough?".

With continued widespread acceptance of pedometers by both researchers and practitioners, evidence-based steps/day indices are needed to facilitate measurement and motivation applications of physical activity (PA) in public health. Therefore, the purpose of this article is to reprise, update, and extend the current understanding of dose-response relationships in terms of pedometer-determined PA. Any pedometer-based PA guideline presumes an accurate and standardized measure of steps; at this time, industry standards establishing quality control of instrumentation is limited to Japan where public health pedometer applications and the 10,000 steps.d slogan are traceable to the 1960s. Adult public health guidelines promote > or =30 min of at least moderate-intensity daily PA, and this translates to 3000-4000 steps if they are: 1) at least moderate intensity (i.e., > or =100 steps.min); 2) accumulated in at least 10-min bouts; and 3) taken over and above some minimal level of PA (i.e., number of daily steps) below which individuals might be classified as sedentary. A zone-based hierarchy is useful for both measurement and motivation purposes in adults: 1) <5000 steps.d (sedentary); 2) 5000-7499 steps.d (low active); 3) 7500-9999 steps.d (somewhat active); 4) > or =10,000-12,499 steps.d (active); and 5) > or =12,500 steps.d (highly active). Evidence to support youth-specific cutoff points is emerging. Criterion-referenced approaches based on selected health outcomes present the potential for advancing evidence-based steps/day standards in both adults and children from a measurement perspective. A tradeoff that needs to be acknowledged and considered is the impact on motivation when evidence-based cutoff points are interpreted by individuals as unattainable goals.

Effect of Pedometer-Based Physical Activity Interventions: A Meta-Analysis.

CRD summary The review concluded that pedometers had a moderate positive effect on physical activity of approximately 2,000 steps per day compared with comparator. There were greater effects in females and the intervention strategy of 10,000 steps/day as a goal. Given uncertain quality of the included studies and a lack of study detail, caution is required when interpreting the authors’ conclusions.

Issues in Outcomes Research: An Overview of Randomization Techniques for Clinical Trials

OBJECTIVE To review and describe randomization techniques used in clinical trials, including simple, block, stratified, and covariate adaptive techniques. BACKGROUND Clinical trials are required to establish treatment efficacy of many athletic training procedures. In the past, we have relied on evidence of questionable scientific merit to aid the determination of treatment choices. Interest in evidence-based practice is growing rapidly within the athletic training profession, placing greater emphasis on the importance of well-conducted clinical trials. One critical component of clinical trials that strengthens results is random assignment of participants to control and treatment groups. Although randomization appears to be a simple concept, issues of balancing sample sizes and controlling the influence of covariates a priori are important. Various techniques have been developed to account for these issues, including block, stratified randomization, and covariate adaptive techniques. ADVANTAGES Athletic training researchers and scholarly clinicians can use the information presented in this article to better conduct and interpret the results of clinical trials. Implementing these techniques will increase the power and validity of findings of athletic medicine clinical trials, which will ultimately improve the quality of care provided.

Validity and reliability of omron pedometers for prescribed and self-paced walking

PURPOSE The purpose of this study was to examine the validity and reliability evidence for the Omron Healthcare HJ-151 and HJ-720ITC pedometers for prescribed and self-paced walking. METHODS A total of 47 adults (24 males, 23 females; age = 24 +/- 4.4 yr.; body mass index = 25.7 +/- 4.2 kg x m(-2)) participated in this study. Under prescribed walking conditions, 34 participants completed three randomized 100-m walking trials through a range of scripted walking speeds (slow, moderate, and very brisk) for each pedometer model. Under self-paced walking conditions, 31 participants completed one 1-mile walk on a standardized course for each model. HJ-151 pedometers were chosen at random from a pool of 54 devices and were worn along the waistband at the right hip, the left hip, and the midback, whereas HJ-720ITC pedometers were chosen from a pool of 24 devices and incorporated right pocket, left pocket, and backpack positions in addition to the three waist-mounted sites. Absolute percent error (APE) scores were calculated to examine pedometer accuracy between actual steps (a criterion measure) and pedometer-determined steps. Coefficient of variation (CoV) was computed to describe interdevice reliability. RESULTS With the exception of the HJ-720ITC at the backpack position in the prescribed walking setting (mean APE = 3.4%), the HJ-151 and the HJ-720ITC accurately reported step counts under prescribed and self-paced conditions (all APE values <3.0%). Moreover, interdevice reliability evidence was established for the HJ-151 and the HJ-720ITC under prescribed and self-paced conditions (all CoV values <2.1%). CONCLUSIONS The Omron HJ-151 and HJ-720ITC pedometers demonstrated validity and reliability at various mounting positions under prescribed and self-paced walking conditions with both healthy and overweight adults.

Convergent validity of the International Physical Activity Questionnaire (IPAQ): meta-analysis

OBJECTIVE The purpose of the present study was to use a meta-analytic approach to examine the convergent validity of the international physical activity questionnaire (IPAQ). DESIGN Systematic review by meta-analysis. SETTING The relevant studies were surveyed from five electronic databases. Primary outcomes of interest were the product-moment correlation coefficients between IPAQ and other instruments. Five separate meta-analyses were performed for each physical activity (PA) category of IPAQ: walking, moderate PA (MPA), total moderate PA (TMPA), vigorous PA (VPA) and total PA (TPA). The corrected mean effect size (ESρ) unaffected by statistical artefacts (i.e., sampling error and reliability) was calculated for each PA category. Selected moderator variables were length of IPAQ (i.e., short and long form), reference period (i.e., last 7 d and usual week), mode of administration (i.e., interviewer and self-reported), language (i.e., English and translated) and instruments (i.e., accelerometer, pedometer and subjective measure). SUBJECTS A total of 152 ESρ across five PA categories were retrieved from twenty-one studies. RESULTS The results showed small- to medium-sized ESρ (0.27-0.49). The highest value was observed in VPA while the lowest value was found in MPA. The ESρ were differentiated by some of the moderator variables across PA categories. CONCLUSIONS The study shows the overall convergent validity of IPAQ within each PA category. Some differences in degree of convergent validity across PA categories and moderator variables imply that different research conditions should be taken into account prior to deciding on use of the appropriate type of IPAQ.

How Many Days Are Enough? A Study of 365 Days of Pedometer Monitoring

This study was designed to determine the number of days of pedometer monitoring necessary to achieve reliable and valid estimates of a 1-year average of step counts in adults based on either consecutive days (CD) or random days (RD) of data collection. Twenty-three participants (16 women; M age = 38 years, SD = 9.9) wore a Yamax SW 200 pedometer and recorded their step counts for 365 consecutive days. Nine measurement periods of various lengths were selected (2, 3, 4, 5, 6, 7, 14, 21, and 30 days). Each measurement period was randomly selected 10 times each for CD and RD from the larger database. For reliability and validity, two-way intraclass correlation coefficients and mean absolute percentage error (MAPE) were calculated, respectively. The year-round average was considered the criterion measure of the “true” habitual physical activity. Data were analyzed separately by CD and RD. At least 5 CD or 6 RD were necessary to achieve an ICC of .80. A minimum of 30 CD or 14 RD were necessary to achieve an MAPE lower than 10%. These findings provide researchers and practitioners with useful information to determine appropriate measurement length and the method of data selection based on a desired level of reliability and validity.

Impact of accelerometer wear time on physical activity data: a NHANES semisimulation data approach

Background Current research practice employs wide-ranging accelerometer wear time criteria to identify a valid day of physical activity (PA) measurement. Objective To evaluate the effects of varying amounts of daily accelerometer wear time on PA data. Methods A total of 1000 days of accelerometer data from 1000 participants (age=38.7±14.3 years; body mass index=28.2±6.7 kg/m2) were selected from the 2005–2006 National Health and Nutrition Examination Study data set. A reference data set was created using 200 random days with 14 h/day of wear time. Four additional samples of 200 days were randomly selected with a wear time of 10, 11, 12 and 13 h/day1. These data sets were used in day-to-day comparison to create four semisimulation data sets (10, 11, 12, 13 h/day) from the reference data set. Differences in step count and time spent in inactivity (<100 cts/min), light (100–1951 cts/min), moderate (1952–5724 cts/min) and vigorous (≥5725 cts/min) intensity PA were assessed using repeated-measures analysis of variance and absolute percent error (APE). Results There were significant differences for moderate intensity PA between the reference data set and semisimulation data sets of 10 and 11 h/day. Differences were observed in 10–13 h/day1 for inactivity and light intensity PA, and 10–12 h/day for steps (all p values <0.05). APE increased with shorter wear time (13 h/day=3.9–14.1%; 12 h/day=9.9–15.2%, 11 h/day=17.1–35.5%; 10 h/day=24.6–40.3%). Discussion These data suggest that using accelerometer wear time criteria of 12 h/day or less may underestimate step count and time spent in various PA levels.

The Association Between Bullying and Psychological Health Among Senior High School Students in Ghana, West Africa

BACKGROUND School-based bullying, a global challenge, negatively impacts the health and development of both victims and perpetrators. This study examined the relationship between bullying victimization and selected psychological variables among senior high school (SHS) students in Ghana, West Africa. METHODS This study utilized data from the 2008 Ghana Global School-based Student Health Survey (GSHS). Prevalence rates of being bullied (95% confidence intervals [CI]) were calculated by each demographic group, as well as each psychological variable. Multiple logistic regression was used to model the relationship of being bullied (physical/nonphysical) on the linear combination of demographic variables. RESULTS A total of 7137 students participated in the 2008 GSHS with 40.1% reporting being bullied. Senior high school-level 1 (lowest grade) students were 3 (95% CI: 2.45-3.68) times more likely to be bullied compared with SHS level 3 (highest grade) students. Victims of bullying were significantly more likely to report negative psychological health compared with those who reported not being bullied. Odds ratios were as follows: signs of depression, 1.97 (95% CI: 1.75-2.21); suicide ideation, 1.72 (95% CI: 1.45-2.05); being so worried that it affects sleep, 2.10 (95% CI: 1.77-2.49); and loneliness, 1.82 (95% CI: 1.49-2.22). There was no significant difference in self-reports of negative psychological health when comparing students who experienced physical forms with those who were bullied in nonphysical ways. CONCLUSION Bullying victimization is a major problem among SHS students. We recommend strengthening of existing proactive anti-bullying programs by taking into account the association between bullying and the psychological health of students.

Exercise Barrier Severity and Perseverance of Active Youth With Physical Disabilities

Purpose: The authors investigated perceived exercise and physical activity barriers of active youth with physical disabilities. Research Method/Design: A 46-item exercise barrier instrument was administered to 145 youth (117 boys and 28 girls, 12 to 19 years of age). Using the Rasch model, the authors estimated barrier severity and youths’ exercise perseverance. Model– data fit was determined by Infit and Outfit statistics ( 0.5 and 1.5). Results: Except for 1 item, the model fit the data well. The most difficult barriers that youth with physical disabilities faced were lack of time and pain or discomfort. The older youth demonstrated higher exercise perseverance than the younger youth. There were no differences in youths’ exercise perseverance scores by gender or National Wheelchair Basketball Association classification. Implications: Removing severe barriers should be a part of future exercise and physical activity interventions targeting this population.

Experimental Determination of Effectiveness of an Individual Information-Centered Approach in Recovering Step-Count Missing Data.

Missing values are a common phenomenon in physical activity research, which has a negative impact on the quality of the data collected. The purpose of this study was to determine empirically the effectiveness of an individual information-centered (II-centered) approach in recovering step-count missing values by comparing the performance of the II-centered approach with the traditional group information-centered approach. Using pedometers, the step counts of 117 participants were measured for 21 consecutive days. A semisimulation approach was used to create a missing data set and several conditions of weekdays, weekend days, or both, were compared under each approach. Two accuracy indexes, Root Mean Square Difference and Mean Signed Difference, were used to determine the effectiveness of the recovery methods, and paired t tests were used to examine the mean differences between the original and the replacement values. The II-centered approach produced a more accurate recovery method. The impact of the findings and future research directions in recovering physical activity data are discussed.