|Methods||Randomised controlled trial|
Aim: To compare the effects of a pedometer-based behavioral intervention (Fitness for Life, FFL) and the traditional army physical ﬁtness (TRAD) programme on physical activity, aerobic ﬁtness, and chronic heart disease risk factors in healthy adult men and women in the Army National Guard (ARNG) who had failed the Army Physical Fitness Test (APFT).
|Participants||Population description: Volunteer, part-time Army National Guard (ARNG) members, who had failed the two-mile run component of the Army Physical Fitness Test.|
Intervention group: 84 participants
Control group: 72 participants
Location: Maryland and Washington, DC, USA.
Inclusion criteria: Volunteer part-time Army National Guard members who had failed the two-mile run component of the Army Physical Fitness Test (APFT), with 12 months or longer before re-enlistment or retirement, and who had no history of CHD or stroke, were not currently taking hypertensive or cholesterol-lowering medications, had not been pregnant within the previous six months, were not post-menopausal or currently taking hormone replacement therapy, or had no major musculoskeletal disorders. Post-menopausal women and women on hormone replacement therapy were excluded owing to their small numbers and potential confounding effect on serum lipids.
Recruitment: From a pool of 261 ARNG soldiers who failed the run portion of the APFT, 156 met the criteria for inclusion in the study and were randomised into two groups.
Age: Mean (SD) for intervention 32.7 (10.1); for controls 32.8 (8.3) years.
Gender: 68.8% male for intervention, 80.4% for controls.
Race: Intervention 50% white, 39% African-American, 7% Asian/Paciﬁc Islander. Controls 31% white, 50% African-American, 7% Asian/Paciﬁc Islander.
Education: Intervention 27% high school graduate, 50% some college, 7% college graduate, 8% some postgraduate, 8% advanced degree. Controls 31% high school graduate, 50% some college, 2% college graduate, 15% some postgraduate, 2% advanced degree.
|Interventions||Duration: 24 weeks (12 weeks of conditioning and 12 weeks of maintenance).|
Intervention: The Fitness for Life (FFL) programme was designed specifically for the reserve components of ARNG and Reserve to teach soldiers usually working a full-time civilian job and a part-time military job to incorporate moderate intensity physical activity (PA) into their daily lives.
1. Professional contact/counselling
Counselling sessions: discussed various activities to increase their daily step count.
Weeks one to four: During brief weekly telephone counselling (< five minutes), pedometer logs were reviewed and feedback provided.
Weeks five to 12: Weekly booster telephone calls, monthly support meetings.
Weeks 13 to 24: Monthly maintenance meetings were continued; telephone calls were tapered to every two weeks, then monthly to increase autonomy.
Monthly group meetings: held to provide support, emphasise relapse prevention, and encourage self monitoring of steps.
2. Goal setting
Pedometer (style Yamax SW 200) worn for self monitoring of their daily steps. Central focus used to motivate and monitor steps through setting step goals, maintaining a daily step log, and promoting activities to increase steps.
Weeks one to four: focused on accumulating daily steps through short bouts of walking combined with behavioral-based PA counselling.
Weeks five to 12: focused on increasing the intensity of soldiers’ activities. Soldiers were taught to rate their perceived exertion while performing moderate-to-high intensity daily activities in their target heart rate range, defined as 60 to 90% of predicted maximum heart rate, calculated as 220 − age. Using the Rating of Perceived Exertion scale, participants gauged the intensity of their activities by means of feedback from their target heart rate. The pedometer continued to be the central focus of behavioral strategies for setting step goals.
Weeks 13 to 24: focused on sustaining gains in the amount of steps and intensity of PA. Participants were expected to continue using the pedometer to monitor their PA. Relapse prevention, self monitoring, and reinforcement were continually emphasised during the maintenance phase.
3. Environmental prompts
Control: The army physical fitness (TRAD) programme follows Army Regulation 350-41, with recommendations detailed in the army’s Field Manual 21-20. The programme consists of 12 weeks of high-intensity conditioning, defined as 75 to 80% of maximum heart rate and 12 weeks of maintenance.
1. Professional contact/counselling
A Master Fitness Trainer, an ARNG soldier who had completed a two-week reserve component training course, oversaw the 12-week training programme.
A brief reminder call was made before each monthly meeting.
Monthly group meetings.
2. Goal setting
Instructed to perform vigorous physical fitness training three to six days per week, including three 30-minute sessions of aerobic training and three 30-minute strength training sessions, performed unsupervised separately or combined, during their normal work day or during leisure time.
Supplementary booklet on the TRAD.
|Outcomes||Physical activity :|
The seven-day physical activity recall (PAR) interview. Amount of time spent asleep (1.0 metabolic equivalent of task (METs) units) and in moderate (four METs), hard (six METs), and very hard (10 METs) intensity physical activity for the previous weekdays and weekend. The seven-day PAR is moderately correlated with an accepted standard measure for cardio-respiratory fitness, the VO₂ max which is the maximum capacity of an individual's body to transport and use oxygen during incremental physical activity. It was assumed that they spent the remaining time in light activities (1.5 METs). To estimate energy expenditure per week, the average number of minutes at each activity level was multiplied by the respective MET value for an estimate of light, moderate, hard, and very hard physical activity in kcal/kg. Total physical activity was the sum of Moderate Intensity,Hard Intensity and Very Hard Intensity physical activity because both interventions were designed to increase these three activity levels, but not Low Intensity.
Pedometer steps (assumed to be: average steps per day over one week). A pedometer (Digiwalker, Yamax SW 200; New Lifestyles, Lees Summit, MO) was used to count the number of steps in a day, which were recorded in a daily pedometer log. This pedometer’s accuracy is within 1% of the actual step count on a 4.88 km sidewalk course. Participants wore the pedometer at the waist from the time they woke up until they went to bed. Control group participants were only given the pedometers for two periods (at baseline and at follow-up, length of testing time unknown) to allow outcome measurement. At the end of the week, pedometers were returned to the study staff. Intervention group participants retained the pedometer throughout the intervention
Weight and height: Measured using a digital scale, with participants in gym shorts and t-shirt without shoes.
Body mass index (BMI): Weight(kg)/height(m)².
Waist circumference: Measured during the late exhalation phase in the standing position.
Blood pressure: Measured using an automatic digital monitor (Model 6009; American diagnostic, Tokyo, Japan) on dominant arm at heart level while participants were seated. Three measurements were taken at one- to two-minute intervals, and the mean of the two closest readings was reported. Cuff sizes reflected the circumference of the participant’s arm. Extreme values were checked by trained personnel, who repeated the digital recording and then recorded blood pressure manually.
Biochemical measures: Fasting venipuncture from the anterior cubital fossa. The samples were allowed to clot at room temperature, then centrifuged at 3,000 rpm for 15 minutes, and the resulting serum was removed and stored at −80°C until analysis. The lipid panel was analysed using the Cholestech LDX system analyser (Cholestech, Hayward, CA), with a sensitivity of 0.8%. All assays were conducted at Johns Hopkins Bayview Campus in the General Clinical Research Center.
Total cholesterol (TC);
Low-density lipoprotein cholesterol (LDL-C);
High-density lipoprotein cholesterol (HDL-C);
TC:HDL-C ratio were calculated.
Other outcomes not reported in this review:
|Statistical analysis||Imputation of missing data: "We used expectation-maximization for imputation estimates of missing data in the group of protocol completers, with SPSS Missing Value Analysis 16.0. The missing data for individual variables ranged between 1% and 19%. Missing data were determined to be missing at random, meeting expectation-maximization assumptions." Hence, expectation-maximisation was undertaken within those returning at follow-up. Imputation was not undertaken for those lost to follow-up.|
Adjustment for clustering: Adjustment not required as participants were randomised individually.
Sample size calculation: "Based on the predicted effect of the intervention with projected 40% attrition, we estimated a total sample size of 156 ARNG soldiers to demonstrate a 10% improvement in APFT scores (effect size, d = 0.65) and PA (effect size d = 0.56) at an α of 0.05 and a power of 0.80."
|Notes||"We also acknowledge the Johns Hopkins Bayview General Clinical Research Center (which is funded by Department of Health and Human Services, National Institutes of Health [NIH], National Center for Research Resources, no. 5 M01 RR0279) for providing core laboratory and data management support and equipment, and the Intramural Research Program of the NIH, National Institute on Aging. Funding for this project was provided by Triservice Nursing Research Program, Johns Hopkins Bayview General Clinical Research Center, the Intramural Research Program of NIH, National Institute on Aging." No other potential conflict of interests stated by the authors.|
|Risk of bias|
|Bias||Authors' judgement||Support for judgement|
|Random sequence generation (selection bias)||Unclear risk||Study described as a "randomized controlled trial". No further information given on the method used to generate the random sequence.|
|Allocation concealment (selection bias)||Unclear risk||No information provided.|
|Blinding of participants and personnel (performance bias) |
|High risk||No information provided.|
It is unlikely that personnel delivering the specific intervention programmes would have been blinded. Participants may have been unaware of the differences between programmes on allocation, but being colleagues in the National Guard, it is possible that communication among participants would have occurred that identified the nature of each intervention.
Although both interventions were active physical training programmes, it is possible that participants may have had a preference for the traditional training programme (control) over the new (pedometer-based) intervention, perhaps contributing to the higher drop-out rate in the pedometer group.
|Blinding of outcome assessment (detection bias) |
Physical activity outcomes
|High risk||Physical activity outcomes were self reported. It is possible that participants in either study group, knowing that the intervention had begun and the direction of expected change, may have exaggerated activity levels. Although this applies to both groups, it may have applied more in one group than another. For example, if participants had stronger belief in the effectiveness of one programme over another (e.g. traditional versus new intervention), or depending on participants' experience of the intervention. Participants in the pedometer arm may have felt greater pressure to report increased steps per day. Participants in the control arm may have felt greater pressure to report increased periods of higher-intensity physical activity.|
|Blinding of outcome assessment (detection bias) |
Disease risk factor outcomes
|Low risk||No information is provided on blinding of assessment of these outcomes, but they are sufficiently objective to make detection bias unlikely.|
|Incomplete outcome data (attrition bias) |
|High risk||One hundred and fifty-six met the criteria and were randomised. 62 (40%) were lost to follow-up (at 12 weeks: 33 Intervention, 19 Control; at 24 weeks: three Intervention, seven Control) due to deployment (15), left ARNG (21), personal reasons (22), injury not related to the study (three), passing Army Physical Fitness Test (one). Reasons were provided, but not for each group.|
"ARNG soldiers who dropped out of the training programme had lower baseline APFT scores, suggesting that less ﬁt individuals require more motivation to complete such a program". This indicates the possibility that data were not missing at random.
Results were reported for participants remaining for the entire study. "We used expectation-maximization for imputation estimates of missing data in the group of protocol completers", but data were not imputed for participants who withdrew.
At least 40% of the baseline sample was missing and the reasons were not very specific. This level of incomplete data is enough to pose a high risk to the results.
|Selective reporting (reporting bias)||Unclear risk||Results for some outcomes measured were not reported (total physical activity, heart rate, triglycerides, very low density lipoprotein), but the reported results included a range of significant and nonsignificant effects, favouring both programmes. It is unlikely that the outcomes omitted were selected based on their results. Study protocol was not available.|
|Other bias||High risk||Baseline data were reported separately for participants who completed or withdrew from the study, so it is difficult to assess the true levels of baseline imbalance. Of those who completed the study, those in the intervention group performed lower levels of moderate and very high intensity physical activity at baseline, which could indicate that the control group was already at a high level of activity and less likely to achieve significant increases (less room to move), or it could indicate a highly active or motivated group who were more likely to achieve significant increases. A number of smaller baseline imbalances were also observed in other outcomes.|