Objectively measuring physical activity: Research and clinical applications of accelerometers Matthew Cox, Ph.D. Instructor Duncan Family Institute Mentored Junior Fellow in Cancer Prevention Research Department of Behavioral Science University of Texas, MD Anderson Cancer Center 1

Overview Benefits of physical activity (PA) PA recommendations Measuring PA How accelerometers work Current levels of PA in U.S. Pros and cons of measuring PA How to choose measurement tool 2

Benefit of physical activity (PA) for cancer prevention/survivorship Decreased all-cause mortality risk Decreased risk of cardiovascular disease and type II diabetes Decreased risk of breast, kidney, lung, endometrial, colon, and prostate cancer During cancer therapy – Improved physical functioning – Decreased fatigue – Decreased anxiety – Decreased sleep disturbances Posttreatment – Improved fitness levels – Decreased body fat and waist circumference – Decrease risk of reoccurrence Benefits moderated by type, frequency, intensity, and duration 3

Review of efficacy and safety for exercise in cancer survivors ACSM Roundtable on Exercise Guidelines for Cancer Survivors,

Current PA Recommendations ACSM Recommendations for healthy yrs: – 30 minutes, five days a week of moderate-intensity aerobic physical activity OR 20 minutes three days a week of vigorous-intensity aerobic activity. – Can benefit from incorporating resistance training for all large muscle groups at least twice a week – Moderate-intensity = noticeably elevated hear rate (e.g., brisk walk) – Vigorous-intensity = substantially increased heart rate (e.g., jogging) ACSM Recommendations for cancer survivors is the same – Without cancer site-specific contraindications 5

How do we measure PA? 6

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Self-report Measures of PA Diary International Physical Activity Questionnaire (IPAQ) Godin Leisure Time Exercise Questionnaire (Godin/GLTEQ) Physical Activity Recall (PAR) 8

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Objective measures of PA Doubly Labeled Water Indirect calorimetry Heart rate 10

Objective measures of PA Pedometers Accelerometers 11

Gold standard for research Uniaxial or triaxial 12 Accelerometers

How accelerometers work 13

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How accelerometers work 15

How accelerometers work Accelerometers count the gravitational units (g) sampling at a frequency of 100Hz or 100 samples per second. Counts are usually aggregated at the minute level The higher the counts the more intense the activity. 16

How accelerometers work Formulas to determine cut points for low, moderate and, vigorous physical activity – Cut points vary by population – Sedentary behavior is less than 100 counts per minute Formulas can convert counts into metabolic equivalent units (METs) No feedback to participants 17

What accelerometers measure Number of minutes of PA and sedentary behavior Bouts of PA and sedentary behavior Intensity of PA behavior Posture (sitting and standing) Can use accelerometer data to calculate: – Energy expenditure – Adherence to PA guidelines 18

Median minutes of PA per day 19

Can accelerometers really be that great? No Provider/Researcher needs to specify – Spurious wear – Non-wear – Minimum wear time – PA and sedentary cut points – How many days of consecutive wear 20

Shameless Plugs We’ve created free software for processing accelerometry data – Package ‘acc’ in R PROSPR shared resource rents accelerometers! 21

Current Levels of PA in cancer survivors (self-report) Breast Cancer Survivors (Irwin et al., Med Sci Sport Exer 2004) – 32% of Breast cancer survivors meet current recommended levels – Obese breast cancer survivors less likely to meet recommendations than others PA levels tend to decline after diagnosis (Blanchard et al., 2003) – Doesn’t return to prediagnosis levels 22

Current Levels of PA in cancer survivors (accelerometers) Non cancer patients (Tucker et al., Am J Prev Med 2011) – Estimates may be much lower with objective measures 62% meeting ASCM recommendations for self report 5%-9.6% using accelerometers (Troiano et al., Med Sci Sport Exer 2008) Cancer survivors – Breast cancer survivors (Johnson-Kozlow et al., IJBNPA 2006) IPAQ overestimates PA in breast cancer survivors by 247% PAR over estimate by 13% – Colon cancer survivors (Boyle et al., Support Care Cancer 2015) Mean daily MVPA minutes with GLTEQ = 26 Mean daily MVPA minutes with accelerometers = 12 23

Pros and Cons of Self-reported PA Pros Easy to administer Fast Cheap Cons Not accurate/valid (maybe) Different measures may not be comparable 24 Rogers, Phys Ther Rev 2010

Pros and Cons of Accelerometers Pros Accurate Measures sedentary behavior Cons Measurement limited to ambulatory activity Pricing Technical PA cut points not developed for all cancer diagnoses Statistical consideration 25 Broderick et al., Support Care Cancer 2015

Median minutes of PA per day 26

How do I choose? Research – It depends – Accelerometers – Alternative exercise testing protocols Clinical – It depends – – Fitbits? 27

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Looking towards the future of measuring PA Wearables that measure more than walking/running 29

What are we measuring? PA is a proxy for other health outcomes – Cardiorespiratory fitness – Energy expenditure – Muscle strength – Biomarkers How do new wearables relate to outcomes? 30

Pooled effects of supervised exercise training, compared with usual care (control), on cardiorespiratory fitness (peak oxygen consumption, VO2peak) by treatment status.Abbreviations: CI, confidence interval; SD, standard deviation. Lee W. Jones et al. The Oncologist 2011;16: ©2011 by AlphaMed Press

Why is the measurement PA important? 32

Social Cognitive Theory (SCT) 33 Social Support Outcome Expectations Self- Regulation Physical Activity Bandura 1986 Modeling Somatic Sensations Self-EfficacyIntervention Time

Physical Activity Outcomes 34 Physical Activity CRF Biomarkers Energy Expenditure Biomarkers Health Outcomes Quality of Life Time

Conclusions Use accelerometers if you can – Know the limitations Measurement of PA is constantly changing Be mindful of the target outcomes – Clinical vs Research 35

Questions? 36