AccelerometersMaria CaninoLeah WagnerLeah Sanders

What is it? How does it work?A small device that measures acceleration forces such as movement. (Actigraph sheet)It contains a sensor to detect changes in movement and produces an electrical signal directly linked to speed of the movement. The signals are then converted into numbers and stored on the device.Worn at wrist or hipRecorded as countsTwo- or three- axis options (anterior/posterior, medial/lateral, vertical)Caloric expenditure and algorithmsEpoch(s) measurement(s)

Broderick, J.M. et al 2013

Uploading/Analyzing DataWe used the ActiGraph accelerometers (GT3X).Initialization period (name, epoch selection, time period, etc.)Data is uploaded to the software to be examined after use.Demographics added at this timeStep count, caloric expenditure, sleep patterns can be evaluatedEpoch, axis movement and steps can be converted into a excel file.

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After Plugging Device In

CostSoftware license for ActiGraph costs around $1,500.Newest monitor (with Bluetooth) costs $225

Device UsesMost studies use accelerometers to assess current physical activity behaviors on a variety of populations.Children, older adults, etc.Device comparisons for accuracy and reliability.Professionals can monitor and prescribe physical activity and exercise in order to enhance ones health.

Accelerometers in Research

Accelerometer PlacementPurpose: Accelerometer optimal sensor location and type of mounting10 subjects participated in the following tasks while wearing five ProMove2 sensors at different placements at the hip held by an elastic belt.Walked/Jogged at various speeds on treadmillPerformed deskwork tasksWalked on level ground

Most lateral position on waistIf sensor interferes with free movement, it may be placed slightly anterior to the body.Must be fitted as tight to the body as possible to avoid any unwanted movement.Boerema, S. et al 2014Findings

Device Usage Across AgesPurpose: Describe physical activity in children (6-11 yr), adolescents (12-19 yr) and adults (20+ yr) through the use of an accelerometer. Data obtained from 2003-2004 NHANES, cross-sectional6,329 provided at least 1 day of data4,867 provided at least 4 or more daysParticipants were interviewed (1-2 hrs) prior to the start of the study as well as had a medical examination.

FindingsMales are more physically active than females.Physical activity and age had an inverse relationship. Age increased, physical activity decreased42% children met recommended 60 minutes of PA a day8% adolescents met the recommendation of 60 minutes of PA a day< 5% adults met the recommendation of 30 minutes of PA a dayPhysical activity was overestimated when given the self-report tool.

Troiano, R. et al 2007

Device Usage in Specific PopulationsPurpose: Examine the relationship between exercise and fatigue over the first three cycles of chemotherapy in women receiving one of the four specified treatments for breast cancer.72 newly diagnosed women with breast cancer participatedThey were instructed to perform home-based moderate-intensity exercises.Assigned a CaltracTM accelerometer to wear to measure physical activityPre- and Post-Variables measured: functional ability (i.e. 12-minute walk), EE and fatigue Subjects recorded daily fatigue (i.e. self-report diary), exercise duration, intensity, and type.

FindingsExercise significantly reduced all four levels of fatigue in all 4 types.As duration of exercise increased, intensity of fatigue decreased.When exercise >60 minutes, fatigue levels increased.Authors mentioned that the use of accelerometers wasnt the most valid method to measure exercise intensity. However, heart rate monitoring was not ideal for the subjects due to anemia caused by chemotherapy.

Schwartz. et al 2001

Our Mini StudyPedometers vs. AccelerometersStep comparisons Consumer-targeted Devices vs. AccelerometersStep comparisonsEnergy expenditure comparisons

Pedometers Comparison Day 1

Pedometers Comparison Day 2

Day 2 continued

Pedometer Overall FindingsPedometers were consistently under recording steps.Accelerometers were inconsistent across all subjects.LocationHip/Wrist PlacementMode of exerciseNot practical during cycling activity for both devices

Consumer-Targeted Devices Comparison* Cycling not an optimal choice for either device.

*Accelerometers have the option of 5 different algorithms to estimate energy expenditure.*Direct calorimetry is necessary for true comparison.

FitBit Overall FindingsSteps between both devices were fairly close.Caloric expenditure dramatically varied.Dependent on device location, placement and algorithm choice

Accelerometer AdvantagesDistinguishes between walk and runMeasures METs for choosing various activitiesCan be used in large sample sizesStores data for extended periods (up to 21 days)User-friendlyGreat for older population and kidsMeasures overall activity for health and current behavior patternsUses epoch for time (i.e. 1-240 seconds options)3-axis Non-invasiveCost?

DisadvantagesCost?Not optimal for athletic performance assessment or enhancementEndurance weight-supporting activities (i.e. cycling, rowing)Not water friendlyLocation and placement is crucialNon-instantaneous feedbackPossible difficulty measuring upper body movement and weight liftingNot ideal for assessing non-exercise activity thermogenesis(NEAT)Caloric expenditure

ReferencesActiGraph. (n.d.). Retrieved September 23, 2014.Boerema, S., VanVelsen, L., Schaake, L., Tnis, T., & Hermens, H. (2014). Optimal sensor placement for measuring physical activity with a 3D accelerometer.Sensors 2014,14(2), 3188-3206.Broderick, J., Ryan, J., O'Donnell, D., & Hussey, J. (2014). A guide to assessing physical activity using accelerometry in cancer patients.Support Care Cancer,22(4), 1121-1130.Schwartz, A., Mori, M., Gao, R., Nail, L., & King, M. (2001). Exercise reduces daily fatigue in women with breast cancer receiving chemotherapy. Medicine & Science in Sports & Exercise, 33(5), 718-23.Troiano, R. (February 24, 2005). Physical activity assessment using accelerometers. Active Living Research Annual Conference. Lecture conducted from Coronado, CA.Troiano, R., Berrigan, D., Dodd, K., Msse, L., Tilert, T., & Mcdowell, M. (2008). Physical Activity In The United States Measured By Accelerometer.Medicine & Science in Sports & Exercise,40, 181-188.

LS**MC*LW*LW*Deskwork: taking a book from shelf, reading, typing, making a phone call, walking through a corridor at a comfortable walking speed

LS*MC*LW*LS*MC*Weartime Kids: 4-9 days, Adults: 3-4 days

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