Physical activity guidelines from around the world are typically expressed in terms of frequency, duration, and intensity parameters. Objective monitoring using pedometers and accelerometers offers a new opportunity to measure and communicate physical activity in terms of steps/day. Various step-based versions or translations of physical activity guidelines are emerging, reflecting public interest in such guidance. However, there appears to be a wide discrepancy in the exact values that are being communicated. It makes sense that step-based recommendations should be harmonious with existing evidence-based public health guidelines that recognize that "some physical activity is better than none" while maintaining a focus on time spent in moderate-to-vigorous physical activity (MVPA). Thus, the purpose of this review was to update our existing knowledge of "How many steps/day are enough?", and to inform step-based recommendations consistent with current physical activity guidelines. Normative data indicate that healthy adults typically take between 4,000 and 18,000 steps/day, and that 10,000 steps/day is reasonable for this population, although there are notable "low active populations." Interventions demonstrate incremental increases on the order of 2,000-2,500 steps/day. The results of seven different controlled studies demonstrate that there is a strong relationship between cadence and intensity. Further, despite some inter-individual variation, 100 steps/minute represents a reasonable floor value indicative of moderate intensity walking. Multiplying this cadence by 30 minutes (i.e., typical of a daily recommendation) produces a minimum of 3,000 steps that is best used as a heuristic (i.e., guiding) value, but these steps must be taken over and above habitual activity levels to be a true expression of free-living steps/day that also includes recommendations for minimal amounts of time in MVPA. Computed steps/day translations of time in MVPA that also include estimates of habitual activity levels equate to 7,100 to 11,000 steps/day. A direct estimate of minimal amounts of MVPA accumulated in the course of objectively monitored free-living behaviour is 7,000-8,000 steps/day. A scale that spans a wide range of incremental increases in steps/day and is congruent with public health recognition that "some physical activity is better than none," yet still incorporates step-based translations of recommended amounts of time in MVPA may be useful in research and practice. The full range of users (researchers to practitioners to the general public) of objective monitoring instruments that provide step-based outputs require good reference data and evidence-based recommendations to be able to design effective health messages congruent with public health physical activity guidelines, guide behaviour change, and ultimately measure, track, and interpret steps/day.

Research examining sedentary behaviour as a potentially independent risk factor for chronic disease morbidity and mortality has expanded rapidly in recent years. We present a narrative overview of the sedentary behaviour measurement literature. Subjective and objective methods of measuring sedentary behaviour suitable for use in population-based research with children and adults are examined. The validity and reliability of each method is considered, gaps in the literature specific to each method identified and potential future directions discussed. To date, subjective approaches to sedentary behaviour measurement, e.g. questionnaires, have focused predominantly on TV viewing or other screen-based behaviours. Typically, such measures demonstrate moderate reliability but slight to moderate validity. Accelerometry is increasingly being used for sedentary behaviour assessments; this approach overcomes some of the limitations of subjective methods, but detection of specific postures and postural changes by this method is somewhat limited. Instruments developed specifically for the assessment of body posture have demonstrated good reliability and validity in the limited research conducted to date. Miniaturization of monitoring devices, interoperability between measurement and communication technologies and advanced analytical approaches are potential avenues for future developments in this field. High-quality measurement is essential in all elements of sedentary behaviour epidemiology, from determining associations with health outcomes to the development and evaluation of behaviour change interventions. Sedentary behaviour measurement remains relatively under-developed, although new instruments, both objective and subjective, show considerable promise and warrant further testing.

Objective: To examine objectively determined sedentary behavior and physical activity (PA) during and outside working hours in full-time office workers. Methods: A total of 170 participants wore an ActiGraph GT1M accelerometer for 7 days. Time spent sedentary (<100 counts/min), in light-intensity PA (100 to 1951 counts/min), and moderate-to-vigorous PA (≥1952 counts/min) was calculated for workdays (including working hours and nonworking hours) and nonworkdays. Results: Participants accumulated significantly higher levels of sedentary behavior (68% vs 60%) and lower levels of light-intensity activity (28% vs 36%) on workdays in comparison with nonworkdays. Up to 71% of working hours were spent sedentary. Individuals who were most sedentary at work were also more sedentary outside work. Conclusions: Those who are most sedentary at work do not compensate by increasing their PA or reducing their sedentary time outside work. Occupational interventions should address workplace and leisure-time sedentary behavior.

Sedentary behavior is defined as any waking behavior characterized by an energy expenditure of 1.5 METS or less while in a sitting or reclining posture. This study examines this definition by assessing the energy cost (METs) of common sitting, standing and walking tasks. Fifty one adults spent 10 min during each activity in a variety of sitting tasks (watching TV, Playing on the Wii, Playing on the PlayStation Portable (PSP) and typing) and non-sedentary tasks (standing still, walking at 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, and 1.6 mph). Activities were completed on the same day in a random order following an assessment of resting metabolic rate (RMR). A portable gas analyzer was used to measure oxygen uptake, and data were converted to units of energy expenditure (METs). Average of standardized MET values for screen-based sitting tasks were: 1.33 (SD: 0.24) METS (TV), 1.41 (SD: 0.28) (PSP), and 1.45 (SD: 0.32) (Typing). The more active, yet still seated, games on the Wii yielded an average of 2.06 (SD: 0.5) METS. Standing still yielded an average of 1.59 (SD: 0.37) METs. Walking MET values increased incrementally with speed from 2.17 to 2.99 (SD: 0.5 - 0.69) METs. The suggested 1.5 MET threshold for sedentary behaviors seems reasonable however some sitting based activities may be classified as non-sedentary. The effect of this on the definition of sedentary behavior and associations with metabolic health needs further investigation.

Objective The ‘single-item measure’ was developed as a short self-report tool for assessing physical activity. The aim of this study was to test the criterion validity of the single-item measure against accelerometry. Design Participants (n=66, 65% female, age: 39±11 years) wore an accelerometer (ActiGraph GT3X) over a 7-day period and on day 8, completed the single-item measure. The number of days of ≥30 min of accelerometer-determined moderate to vigorous intensity physical activity (MVPA) were calculated using two approaches; first by including all minutes of MVPA and second by including only MVPA accumulated in bouts of ≥10 min (counts/min ≥1952). Associations between the single-item measure and accelerometer were examined using Spearman correlations and 95% limits of agreement. Percent agreement and κ statistic were used to assess agreement between the tools in classifying participants as sufficiently/insufficiently active. Results Correlations between the number of days of ≥30 min MVPA recorded by the single-item and accelerometer ranged from 0.46 to 0.57. Participants underreported their activity on the single-item measure (−1.59 days) when compared with all objectively measured MVPA, but stronger congruence was observed when compared with MVPA accumulated in bouts of ≥10 min (0.38 days). Overall agreement between the single-item and accelerometry in classifying participants as sufficiently/insufficiently active was 58% (k=0.23, 95% CI 0.05 to 0.41) when including all MVPA and 76% (k=0.39, 95% CI 0.14 to 0.64) when including activity undertaken in bouts of ≥10 min. Conclusions The single-item measure is a valid screening tool to determine whether respondents are sufficiently active to benefit their health.