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Papers by Alberto Flórez Pregonero

Medicine & Science in Sports & Exercise, 2014

calculated for each stride for the STEP and gait trials. The mean and SD of the ML harmonic ratio... more calculated for each stride for the STEP and gait trials. The mean and SD of the ML harmonic ratio were calculated across all strides in the trial for each participant, as was step time variability (STSD). Non-normally distributed variables were log transformed. STEP and gait variable relationships were tested using Pearson correlations. GAIT and SCT GAIT variable means were compared with paired t-tests. RESULTS: STEP # of steps correlated with gait speed for GAIT (r = 0.458, p = 0.004) and SCT GAIT (r = 0.384, p = 0.017), but with no other variable. STEP harmonic ratio was related to SCT GAIT and not GAIT; STEP mean ML harmonic ratio was related to SCT GAIT mean ML harmonic ratio (r = 0.372, p = 0.023). STEP ML harmonic ratio SD correlated with SCT GAIT ML harmonic ratio SD (r = 0.436, p = 0.007). The dual-task disrupted gait speed, rhythmicity, and smoothness: during SCT GAIT, mean gait speed was slower than GAIT (1.20 (0.21) m/s vs. 1.28 (0.18) m/s, p = 0.007), median STSD was higher (0.024 (0.018) s vs. 0.018 (0.022) s, p < 0.001), and mean ML harmonic ratio was lower (2.234 (0.585) vs. 2.45 (0.749), p = 0.006). CONCLUSIONS: ML smoothness during the STEP test was related to gait ML smoothness in the dual-task condition, but the strength of the relationship was weak. The clinicallyaccessible measure of STEP performance (# of steps) did not correlate with the gait ML smoothness and rhythmicity variables, further reducing its value as a clinical test.

Sensors, Nov 12, 2018

The purpose of this study was to classify, and model various physical activities performed by a d... more The purpose of this study was to classify, and model various physical activities performed by a diverse group of participants in a supervised lab-based protocol and utilize the model to identify physical activity in a free-living setting. Wrist-worn accelerometer data were collected from (N = 152) adult participants; age 18-64 years, and processed the data to identify and model unique physical activities performed by the participants in controlled settings. The Gaussian mixture model (GMM) and the hidden Markov model (HMM) algorithms were used to model the physical activities with time and frequency-based accelerometer features. An overall model accuracy of 92.7% and 94.7% were achieved to classify 24 physical activities using GMM and HMM, respectively. The most accurate model was then used to identify physical activities performed by 20 participants, each recorded for two free-living sessions of approximately six hours each. The free-living activity intensities were estimated with 80% accuracy and showed the dominance of stationary and light intensity activities in 36 out of 40 recorded sessions. This work proposes a novel activity recognition process to identify unsupervised free-living activities using lab-based classification models. In summary, this study contributes to the use of wearable sensors to identify physical activities and estimate energy expenditure in free-living settings.

Journal of Gerontological Nursing, May 1, 2022

Background: Interventions to promote physical activity among women breast cancer survivors (BCS) ... more Background: Interventions to promote physical activity among women breast cancer survivors (BCS) in low to middle-income countries are limited. We assessed the acceptability and preliminary effectiveness of a theory-driven group dance intervention for BCS delivered in Bogotá, Colombia. Methods: We conducted a quasi-experimental study employing a mixed-methods approach to assess the 8-week, 3 times/week group dance intervention. The effect of the intervention on participants' physical activity levels (measured by accelerometry), motivation to engage in physical activity, and quality of life were evaluated using Generalized Estimating Equations analysis. The qualitative method included semi-structured interviews thematically analyzed to evaluate program acceptability. Results: Sixty-four BCS were allocated to the intervention (N=31) or the control groups (N=33). In the intervention arm, 84% attended ≥60% of sessions. We found increases on average minutes of moderate-to-vigorous physical activity per day (intervention: +8.99 vs control:-3.7 min; p = 0.01), and in ratings of motivation (intervention change score= 0.45, vs. control change score=-0.05; p = 0.01). BCS reported improvements in perceived behavioral capabilities to be active, captured through the interviews. Conclusions: The high attendance, behavioral changes, and successful delivery indicate the potential effectiveness, feasibility, and scalability of the intervention for BCS in Colombia.

Medicine & Science in Sports & Exercise, 2014

The journals of gerontology. Series A, Biological sciences and medical sciences, Jan 2, 2016

The accuracy of step detection in consumer-based wearable activity monitors in older adults with ... more The accuracy of step detection in consumer-based wearable activity monitors in older adults with varied ambulatory abilities is not known. We assessed the validity of two hip-worn (Fitbit One and Omron HJ-112) and two wrist-worn (Fitbit Flex and Jawbone UP) activity monitors in 99 older adults of varying ambulatory abilities and also included the validity results from the ankle-worn StepWatch as a comparison device. Nonimpaired, impaired (Short Physical Performance Battery Score < 9), cane-using, or walker-using older adults (62 and older) ambulated at a self-selected pace for 100 m wearing all activity monitors simultaneously. The criterion measure was directly observed steps. Intraclass correlation coefficients (ICC), mean percent error and mean absolute percent error, equivalency, and Bland-Altman plots were used to assess accuracy. Nonimpaired adults steps were underestimated by 4.4% for StepWatch (ICC = 0.87), 2.6% for Fitbit One (ICC = 0.80), 4.5% for Omron HJ-112 (ICC = 0....

Measurement of sedentary behaviours in surveillance systems and in population studies involves th... more Measurement of sedentary behaviours in surveillance systems and in population studies involves the use of subjective and objective methods. Subjective methods have traditionally included questionnaires to provide a snapshot of sedentary behaviours and to quantify the time spent in sedentary behaviours as categorized by energy expenditure and posture. New horizons for subjective methodologies include smartphone applications that allow measurement of the facets and sub-categories of the Consensus Taxonomy of Sedentary Behaviours. Objective methods have used pedometers to determine the proportion of the populations with <5000 steps/day as defined by the Step-defined Sedentary Behaviour Index and accelerometers to determine the time spent in sedentary behaviours defined as <100 acceleration counts per minute. New horizons for objective methodologies include integrated motion- and posture sensors to assess time spent in metabolic intensities ≤1.5 metabolic equivalents (METs) and si...

Background Despite their utility in accessing ambulatory movement, pedometers have not been used ... more Background Despite their utility in accessing ambulatory movement, pedometers have not been used consistently to monitor physical activity in U.S. surveillance systems. This study was designed to determine the feasibility of using pedometers to assess daily steps taken in a sub-sample of adults from Maricopa County who completed the 2014 Arizona Behavioral Risk Factor Surveillance System Survey. Methods Respondents were sent an Omron HJ324U pedometer, a logbook to record steps taken, and a walking questionnaire. The pedometer was worn for 7 days. Feasibility was assessed for acceptability (interest in study), demand (procedures followed correctly), implementation (time to complete study), and practicality (cost). Results Acceptability was modest with 23.9% (830/3476) agreeing to participate. Among those participating (92.9%; 771/830), 50.1% (386/771) returned the logbook. Demand was modest with 39.3% (303/771) of logbooks returned with valid data. Implementation represented 5 months...

The purpose of this study was to determine the perceptions of quality of life related to health b... more The purpose of this study was to determine the perceptions of quality of life related to health by users of a massive program of physical activity (PMAF), be...

Journal for the Measurement of Physical Behaviour

Background: Published accelerometer cut-points have limited accuracy in measuring sedentary (SED)... more Background: Published accelerometer cut-points have limited accuracy in measuring sedentary (SED) and stationary time (STA) despite hip or wrist placement. Few studies have evaluated established cut-points to measure SED and STA in free-living settings. Methods: This study evaluated published uniaxial and triaxial cut-points of accelerometers and identified optimal cut-points to measure SED and STA. Twenty participants, ages 18–65, wore three ActiGraph GT3X+ (one on each wrist and the waist) and two GENEActiv accelerometers (one on each wrist) for one weekday and one weekend day during simultaneous direct observation of movement. ActiGraph uniaxial cut-points (50, 100, 150, and 500 counts per minute [cpm]) and GENEActiv vector magnitude cut-points (VMCP; 217 and 386 cpm) were compared against the criterion measure of direct observation. As compared to the criterion, accuracy was determined with mean percent error, Bland-Altman plots, kappa coefficient, sensitivity, and specificity. ...

Cadernos de Saúde Pública, 2014

Associations between time spent traveling in motor vehicles and physical activity in Colombian ad... more Associations between time spent traveling in motor vehicles and physical activity in Colombian adults from urban areas Asociaciones entre el tiempo de viaje en vehículos motorizados y la actividad física en adultos colombianos de zonas urbanas Associações entre o tempo gasto em viagens em veículos motorizados e atividade física em adultos colombianos de áreas urbanas

Preventive medicine, Jan 1, 2012

This study examined associations between time spent traveling in motor vehicles per week (TSTMV) ... more This study examined associations between time spent traveling in motor vehicles per week (TSTMV) and BMI and abdominal obesity (AO) among Colombian adults residing in urban areas who do not own car.Secondary data analysis of the 2005 National Nutrition Survey of Colombia was conducted. TSTMV was assessed using the long International Physical Activity Questionnaire. Body composition was measured in 7900 adults. Polytomous and binary logistic regressions were conducted, stratified by gender and adjusted for confounders, including physical activity (PA).Forty-two percent of participants were either overweight or obese according to their BMI, and 22.4% had AO. Males in the middle (10 to 149 min) and highest (> 150 min) TSTMV tertiles were more likely to be overweight (POR = 1.58, 95% CI = 1.13–2.21 and POR = 1.55, 95% CI = 1.12–2.15 respectively, p-trend = 0.012), obese (POR = 2.39, 95% CI = 1.43–3.99 and POR = 1.93, 95% CI = 1.22–3.08 respectively, p trend = 0.019) and to have AO (POR = 1.81, 95% CI = 1.18–2.78 and POR = 1.73, 95% CI = 1.18–2.54 respectively, p-trend = 0.009). Associations were not significant in females.TSTMV was positively associated with overweight and AO in adult Colombian males even after adjusting for PA. These findings highlight the potential deleterious health effects of sedentary behaviors such as prolonged traveling time, independently of having met PA recommendations.► Sedentary behaviors have deleterious health effects. ► The deleterious effects of sedentary behaviors are independent of physical activity. ► Most of Latin-America urban population spends long periods travelling in vehicles. ► In Colombian males travelling time is associated with overweight and obesity.

Medicine & Science in Sports & Exercise, 2014

calculated for each stride for the STEP and gait trials. The mean and SD of the ML harmonic ratio... more calculated for each stride for the STEP and gait trials. The mean and SD of the ML harmonic ratio were calculated across all strides in the trial for each participant, as was step time variability (STSD). Non-normally distributed variables were log transformed. STEP and gait variable relationships were tested using Pearson correlations. GAIT and SCT GAIT variable means were compared with paired t-tests. RESULTS: STEP # of steps correlated with gait speed for GAIT (r = 0.458, p = 0.004) and SCT GAIT (r = 0.384, p = 0.017), but with no other variable. STEP harmonic ratio was related to SCT GAIT and not GAIT; STEP mean ML harmonic ratio was related to SCT GAIT mean ML harmonic ratio (r = 0.372, p = 0.023). STEP ML harmonic ratio SD correlated with SCT GAIT ML harmonic ratio SD (r = 0.436, p = 0.007). The dual-task disrupted gait speed, rhythmicity, and smoothness: during SCT GAIT, mean gait speed was slower than GAIT (1.20 (0.21) m/s vs. 1.28 (0.18) m/s, p = 0.007), median STSD was higher (0.024 (0.018) s vs. 0.018 (0.022) s, p < 0.001), and mean ML harmonic ratio was lower (2.234 (0.585) vs. 2.45 (0.749), p = 0.006). CONCLUSIONS: ML smoothness during the STEP test was related to gait ML smoothness in the dual-task condition, but the strength of the relationship was weak. The clinicallyaccessible measure of STEP performance (# of steps) did not correlate with the gait ML smoothness and rhythmicity variables, further reducing its value as a clinical test.

Sensors, Nov 12, 2018

The purpose of this study was to classify, and model various physical activities performed by a d... more The purpose of this study was to classify, and model various physical activities performed by a diverse group of participants in a supervised lab-based protocol and utilize the model to identify physical activity in a free-living setting. Wrist-worn accelerometer data were collected from (N = 152) adult participants; age 18-64 years, and processed the data to identify and model unique physical activities performed by the participants in controlled settings. The Gaussian mixture model (GMM) and the hidden Markov model (HMM) algorithms were used to model the physical activities with time and frequency-based accelerometer features. An overall model accuracy of 92.7% and 94.7% were achieved to classify 24 physical activities using GMM and HMM, respectively. The most accurate model was then used to identify physical activities performed by 20 participants, each recorded for two free-living sessions of approximately six hours each. The free-living activity intensities were estimated with 80% accuracy and showed the dominance of stationary and light intensity activities in 36 out of 40 recorded sessions. This work proposes a novel activity recognition process to identify unsupervised free-living activities using lab-based classification models. In summary, this study contributes to the use of wearable sensors to identify physical activities and estimate energy expenditure in free-living settings.

Journal of Gerontological Nursing, May 1, 2022

Background: Interventions to promote physical activity among women breast cancer survivors (BCS) ... more Background: Interventions to promote physical activity among women breast cancer survivors (BCS) in low to middle-income countries are limited. We assessed the acceptability and preliminary effectiveness of a theory-driven group dance intervention for BCS delivered in Bogotá, Colombia. Methods: We conducted a quasi-experimental study employing a mixed-methods approach to assess the 8-week, 3 times/week group dance intervention. The effect of the intervention on participants' physical activity levels (measured by accelerometry), motivation to engage in physical activity, and quality of life were evaluated using Generalized Estimating Equations analysis. The qualitative method included semi-structured interviews thematically analyzed to evaluate program acceptability. Results: Sixty-four BCS were allocated to the intervention (N=31) or the control groups (N=33). In the intervention arm, 84% attended ≥60% of sessions. We found increases on average minutes of moderate-to-vigorous physical activity per day (intervention: +8.99 vs control:-3.7 min; p = 0.01), and in ratings of motivation (intervention change score= 0.45, vs. control change score=-0.05; p = 0.01). BCS reported improvements in perceived behavioral capabilities to be active, captured through the interviews. Conclusions: The high attendance, behavioral changes, and successful delivery indicate the potential effectiveness, feasibility, and scalability of the intervention for BCS in Colombia.

Medicine & Science in Sports & Exercise, 2014

The journals of gerontology. Series A, Biological sciences and medical sciences, Jan 2, 2016

The accuracy of step detection in consumer-based wearable activity monitors in older adults with ... more The accuracy of step detection in consumer-based wearable activity monitors in older adults with varied ambulatory abilities is not known. We assessed the validity of two hip-worn (Fitbit One and Omron HJ-112) and two wrist-worn (Fitbit Flex and Jawbone UP) activity monitors in 99 older adults of varying ambulatory abilities and also included the validity results from the ankle-worn StepWatch as a comparison device. Nonimpaired, impaired (Short Physical Performance Battery Score < 9), cane-using, or walker-using older adults (62 and older) ambulated at a self-selected pace for 100 m wearing all activity monitors simultaneously. The criterion measure was directly observed steps. Intraclass correlation coefficients (ICC), mean percent error and mean absolute percent error, equivalency, and Bland-Altman plots were used to assess accuracy. Nonimpaired adults steps were underestimated by 4.4% for StepWatch (ICC = 0.87), 2.6% for Fitbit One (ICC = 0.80), 4.5% for Omron HJ-112 (ICC = 0....

Measurement of sedentary behaviours in surveillance systems and in population studies involves th... more Measurement of sedentary behaviours in surveillance systems and in population studies involves the use of subjective and objective methods. Subjective methods have traditionally included questionnaires to provide a snapshot of sedentary behaviours and to quantify the time spent in sedentary behaviours as categorized by energy expenditure and posture. New horizons for subjective methodologies include smartphone applications that allow measurement of the facets and sub-categories of the Consensus Taxonomy of Sedentary Behaviours. Objective methods have used pedometers to determine the proportion of the populations with <5000 steps/day as defined by the Step-defined Sedentary Behaviour Index and accelerometers to determine the time spent in sedentary behaviours defined as <100 acceleration counts per minute. New horizons for objective methodologies include integrated motion- and posture sensors to assess time spent in metabolic intensities ≤1.5 metabolic equivalents (METs) and si...

Background Despite their utility in accessing ambulatory movement, pedometers have not been used ... more Background Despite their utility in accessing ambulatory movement, pedometers have not been used consistently to monitor physical activity in U.S. surveillance systems. This study was designed to determine the feasibility of using pedometers to assess daily steps taken in a sub-sample of adults from Maricopa County who completed the 2014 Arizona Behavioral Risk Factor Surveillance System Survey. Methods Respondents were sent an Omron HJ324U pedometer, a logbook to record steps taken, and a walking questionnaire. The pedometer was worn for 7 days. Feasibility was assessed for acceptability (interest in study), demand (procedures followed correctly), implementation (time to complete study), and practicality (cost). Results Acceptability was modest with 23.9% (830/3476) agreeing to participate. Among those participating (92.9%; 771/830), 50.1% (386/771) returned the logbook. Demand was modest with 39.3% (303/771) of logbooks returned with valid data. Implementation represented 5 months...

The purpose of this study was to determine the perceptions of quality of life related to health b... more The purpose of this study was to determine the perceptions of quality of life related to health by users of a massive program of physical activity (PMAF), be...

Journal for the Measurement of Physical Behaviour

Background: Published accelerometer cut-points have limited accuracy in measuring sedentary (SED)... more Background: Published accelerometer cut-points have limited accuracy in measuring sedentary (SED) and stationary time (STA) despite hip or wrist placement. Few studies have evaluated established cut-points to measure SED and STA in free-living settings. Methods: This study evaluated published uniaxial and triaxial cut-points of accelerometers and identified optimal cut-points to measure SED and STA. Twenty participants, ages 18–65, wore three ActiGraph GT3X+ (one on each wrist and the waist) and two GENEActiv accelerometers (one on each wrist) for one weekday and one weekend day during simultaneous direct observation of movement. ActiGraph uniaxial cut-points (50, 100, 150, and 500 counts per minute [cpm]) and GENEActiv vector magnitude cut-points (VMCP; 217 and 386 cpm) were compared against the criterion measure of direct observation. As compared to the criterion, accuracy was determined with mean percent error, Bland-Altman plots, kappa coefficient, sensitivity, and specificity. ...

Cadernos de Saúde Pública, 2014

Associations between time spent traveling in motor vehicles and physical activity in Colombian ad... more Associations between time spent traveling in motor vehicles and physical activity in Colombian adults from urban areas Asociaciones entre el tiempo de viaje en vehículos motorizados y la actividad física en adultos colombianos de zonas urbanas Associações entre o tempo gasto em viagens em veículos motorizados e atividade física em adultos colombianos de áreas urbanas

Preventive medicine, Jan 1, 2012

This study examined associations between time spent traveling in motor vehicles per week (TSTMV) ... more This study examined associations between time spent traveling in motor vehicles per week (TSTMV) and BMI and abdominal obesity (AO) among Colombian adults residing in urban areas who do not own car.Secondary data analysis of the 2005 National Nutrition Survey of Colombia was conducted. TSTMV was assessed using the long International Physical Activity Questionnaire. Body composition was measured in 7900 adults. Polytomous and binary logistic regressions were conducted, stratified by gender and adjusted for confounders, including physical activity (PA).Forty-two percent of participants were either overweight or obese according to their BMI, and 22.4% had AO. Males in the middle (10 to 149 min) and highest (> 150 min) TSTMV tertiles were more likely to be overweight (POR = 1.58, 95% CI = 1.13–2.21 and POR = 1.55, 95% CI = 1.12–2.15 respectively, p-trend = 0.012), obese (POR = 2.39, 95% CI = 1.43–3.99 and POR = 1.93, 95% CI = 1.22–3.08 respectively, p trend = 0.019) and to have AO (POR = 1.81, 95% CI = 1.18–2.78 and POR = 1.73, 95% CI = 1.18–2.54 respectively, p-trend = 0.009). Associations were not significant in females.TSTMV was positively associated with overweight and AO in adult Colombian males even after adjusting for PA. These findings highlight the potential deleterious health effects of sedentary behaviors such as prolonged traveling time, independently of having met PA recommendations.► Sedentary behaviors have deleterious health effects. ► The deleterious effects of sedentary behaviors are independent of physical activity. ► Most of Latin-America urban population spends long periods travelling in vehicles. ► In Colombian males travelling time is associated with overweight and obesity.