Comparison of accelerometry and oxymetry for measuring daily physical activity

Differential effects of physical activity and sleep duration on cognitive function in young adults

PURPOSE

Although exercise and sleep duration habits are associated with cognitive function, their beneficial effects on cognitive function remain unclear. We aimed to examine the effect of sleep duration and daily physical activity on cognitive function, elucidating the neural mechanisms using near-infrared spectroscopy (NIRS).

METHODS

A total of 23 healthy young adults (age 22.0 ± 2.2 years) participated in this study. Exercise amount was assessed using a uniaxial accelerometer. We evaluated total sleep time (TST) and sleep efficiency by actigraphy. Cognitive function was tested using the N-back task, the Wisconsin Card Sorting Test (WCST), and the Continuous Performance Test-Identical Pairs (CPT-IP), and the cortical oxygenated hemoglobin levels during a word fluency task were measured with NIRS.

RESULTS

Exercise amount was significantly correlated with reaction time on 0- and 1-back tasks (r = -0.602, p = 0.002; r = -0.446, p = 0.033, respectively), whereas TST was significantly correlated with % corrects on the 2-back task (r = 0.486, p = 0.019). Multiple regression analysis, including exercise amount, TST, and sleep efficiency, revealed that exercise amount was the most significant factor for reaction time on 0- and 1-back tasks (β = -0.634, p = 0.002; β = -0.454, p = 0.031, respectively), and TST was the most significant factor for % corrects on the 2-back task (β = 0.542, p = 0.014). The parameter measured by WCST and CPT-IP was not significantly correlated with TST or exercise amount. Exercise amount, but not TST, was significantly correlated with the mean area under the NIRS curve in the prefrontal area (r = 0.492, p = 0.017).

CONCLUSION

Exercise amount and TST had differential effects on working memory and cortical activation in the prefrontal area. Daily physical activity and appropriate sleep duration may play an important role in working memory.

A community health worker-led lifestyle behavior intervention for Latina (Hispanic) women: feasibility and outcomes of a randomized controlled trial

BACKGROUND

Low-income Latinas (Hispanics) face risk for cardiovascular disease due to high rates of overweight/obesity, sedentary lifestyle, and other factors. Limited access to health care and language barriers may prevent delivery of health promotion messages. Targeted approaches, including the integration of community health workers, may be required to promote healthy lifestyle and prevent chronic disease in underserved ethnic minority groups. The term commonly used to refer to female community health workers in Latino communities is "promotora(s)."

OBJECTIVES

This study evaluates the outcomes and feasibility of a promotora-led lifestyle behavior intervention for overweight, immigrant Latinas.

METHODS

A community prevention model was employed in planning and implementing this study. A randomized controlled trial design was used. A Community Advisory Board provided expertise in evaluating feasibility of study implementation in the community and other important guidance. The sample was comprised of 223 women aged 35-64 years, predominantly with low income and ≤8th grade education. The culturally tailored Lifestyle Behavior Intervention included group education (8 classes based upon Su Corazon, Su Vida), followed by 4 months of individual teaching and coaching (home visits and telephone calls). The control group received a comparable length educational program and follow-up contacts. Evaluations were conducted at baseline and at 6 and 9 months using a dietary habits questionnaire, accelerometer readings of physical activity, and clinical measures (body mass index, weight, waist circumference, blood pressure, lipids, blood glucose). Data were collected between January 2010 and August 2012.

RESULTS

Women in the intervention group improved significantly in dietary habits, waist circumference, and physical activity in comparison to those in the control group. A treatment dosage effect was observed for weight and waist circumference. Knowledge about heart disease increased. High attendance at classes and participation in the individual teaching and counseling sessions and high retention rates support the feasibility and acceptability of the promotora-led lifestyle behavior intervention.

CONCLUSIONS

Our findings demonstrate that lifestyle behaviors and other risk factors of overweight Latina women may be improved through a promotora-led lifestyle behavior intervention. Feasibility of implementing this intervention in community settings and engaging promotoras as facilitators is supported.

Physical activity and cardiometabolic characteristics in overweight Latina women

This community-based study examined physical activity (PA) in relation to cardiometabolic risk factors among 223 adult, immigrant Latina women who were overweight or obese. Participants were predominantly of Mexican descent, married and low-income. Data were obtained through accelerometer readings and clinical measures (e.g., BMI, waist circumference, blood pressure, lipid profile, fasting blood sugar). Findings showed that many women were active (mean step count = 8,575 ± 3,191); 27.6 % achieved 10,000 steps per day, and only 11 % were sedentary. They engaged in short bouts of moderate PA rather than long-sustained moderate-to-vigorous activity. Three or more MetS traits were present in 45.3 % of the women, raising concerns about risk for diabetes and cardiovascular disease. More active women had lower BMI, weight, waist circumference, and triglycerides levels. Results point to the importance of targeting maintenance of PA in active women and intervening with culturally tailored programs to promote healthier behavior in those who are sedentary or somewhat active.

Clinical usefulness of indoor life-space assessment in community-dwelling older adults certified as needing support or care

PURPOSE

This study aimed to develop a questionnaire to evaluate indoor life-space mobility and assess its validity in community-dwelling older adults certified as needing support or care.

METHODS

The participants included 37 community-dwelling older adults undergoing home-visit rehabilitation (mean age: 78.5±7.0 years). We developed a questionnaire to assess the degree of indoor life-space mobility (home-based life-space assessment (Hb-LSA)), evaluating the functional status (life-space assessment (LSA), time spent away from bed, functional independence measure (FIM), bedside mobility scale (BMS)), physical function (hand grip power (HGP), 30-second chair stand (CS-30), one-leg standing (OLS)) and cognitive status (mental status questionnaire (MSQ)).

RESULTS

The average Hb-LSA score was 56.3±24.3 (minimum 4 to maximum 102.5). The test-retest reliability was high (intraclass correlation coefficients: (1, 1)=0.986, (1, 2)=0.993). The Hb-LSA scores were significantly associated with the LSA (r=0.897), time spent away from bed (r=0.497), FIM (r=0.786), BMS (r=0.720), HGP (r=0.388), CS-30 (r=0.541) and OLS (r=0.455). There were no significant associations between the Hb-LSA scores and the FIM cognitive subscores (r=0.180) or MSQ scores (r=-0.240). The Hb-LSA scores were significantly higher among the participants able to move independently indoors (75.8±18.8 points) than in those who required help to move (45.7±20.2 points).

CONCLUSIONS

The Hb-LSA is a useful, reliable and valid tool for assessing the degree of indoor physical mobility in the life-space. The Hb-LSA score is related to the degree of independence of indoor mobility.

Validity of activity monitors in health and chronic disease: a systematic review

The assessment of physical activity in healthy populations and in those with chronic diseases is challenging. The aim of this systematic review was to identify whether available activity monitors (AM) have been appropriately validated for use in assessing physical activity in these groups. Following a systematic literature search we found 134 papers meeting the inclusion criteria; 40 conducted in a field setting (validation against doubly labelled water), 86 in a laboratory setting (validation against a metabolic cart, metabolic chamber) and 8 in a field and laboratory setting. Correlation coefficients between AM outcomes and energy expenditure (EE) by the criterion method (doubly labelled water and metabolic cart/chamber) and percentage mean differences between EE estimation from the monitor and EE measurement by the criterion method were extracted. Random-effects meta-analyses were performed to pool the results across studies where possible. Types of devices were compared using meta-regression analyses. Most validation studies had been performed in healthy adults (n = 118), with few carried out in patients with chronic diseases (n = 16). For total EE, correlation coefficients were statistically significantly lower in uniaxial compared to multisensor devices. For active EE, correlations were slightly but not significantly lower in uniaxial compared to triaxial and multisensor devices. Uniaxial devices tended to underestimate TEE (−12.07 (95%CI; -18.28 to −5.85) %) compared to triaxial (−6.85 (95%CI; -18.20 to 4.49) %, p = 0.37) and were statistically significantly less accurate than multisensor devices (−3.64 (95%CI; -8.97 to 1.70) %, p<0.001). TEE was underestimated during slow walking speeds in 69% of the lab validation studies compared to 37%, 30% and 37% of the studies during intermediate, fast walking speed and running, respectively. The high level of heterogeneity in the validation studies is only partly explained by the type of activity monitor and the activity monitor outcome. Triaxial and multisensor devices tend to be more valid monitors. Since activity monitors are less accurate at slow walking speeds and information about validated activity monitors in chronic disease populations is lacking, proper validation studies in these populations are needed prior to their inclusion in clinical trials.

Reliability and validity of CHAMPS self-reported sedentary-to-vigorous intensity physical activity in older adults

BACKGROUND

Recent research highlights the potential value of differentiating between categories of physical activity intensities as predictors of health and well-being. This study sought to assess reliability and concurrent validity of sedentary (ie, 1 METs), low-light (ie, >1 and ≤2 METs; eg, playing cards), high-light (ie, >2 and <3 METs; eg, light walking), moderate-to-vigorous physical activity (MVPA, ≥3 METs), and "total activity" (≥2 METs) from the CHAMPS survey. Further, this study explored over-reporting and double-reporting.

METHODS

CHAMPS data were gathered from the Seniors Neighborhood Quality of Life Study, an observational study of adults aged 65+ years conducted in 2 US regions.

RESULTS

Participants (N = 870) were 75.3 ± 6.8 years old, with 56% women and 71% white. The CHAMPS sedentary, low-light, high-light, total activity, and MVPA variables had acceptable test-retest reliability (ICCs 0.56-0.70). The CHAMPS high-light (ρ = 0.27), total activity (ρ = 0.34), and MVPA (ρ = 0.37) duration scales were moderately associated with accelerometry minutes of corresponding intensity, and the sedentary scale (ρ = 0.12) had a lower, but significant correlation. Results suggested that several CHAMPS items may be susceptible to over-reporting (eg, walking, housework).

CONCLUSIONS

CHAMPS items effectively measured high-light, total activity, and MVPA in seniors, but further refinement is needed for sedentary and low-light activity.

Measurement of human energy expenditure, with particular reference to field studies: an historical perspective

Over the years, techniques for the study of human movement have ranged in complexity and precision from direct observation of the subject through activity diaries, questionnaires, and recordings of body movement, to the measurement of physiological responses, studies of metabolism and indirect and direct calorimetry. This article reviews developments in each of these domains. Particular reference is made to their impact upon the continuing search for valid field estimates of activity patterns and energy expenditures, as required by the applied physiologist, ergonomist, sports scientist, nutritionist and epidemiologist. Early observers sought to improve productivity in demanding employment. Direct observation and filming of workers were supplemented by monitoring of heart rates, ventilation and oxygen consumption. Such methods still find application in ergonomics and sport, but many investigators are now interested in relationships between habitual physical activity and chronic disease. Even sophisticated questionnaires still do not provide valid information on the absolute energy expenditures associated with good health. Emphasis has thus shifted to use of sophisticated pedometer/accelerometers, sometimes combining their output with GPS and other data. Some modern pedometer/accelerometers perform well in the laboratory, but show substantial systematic errors relative to laboratory reference criteria such as the metabolism of doubly labeled water when assessing the varied activities of daily life. The challenge remains to develop activity monitors that are sufficiently inexpensive for field use, yet meet required accuracy standards. Possibly, measurements of oxygen consumption by portable respirometers may soon satisfy part of this need, although a need for valid longer term monitoring will remain.

Accelerometer validity and placement for detection of changes in physical activity in dogs under controlled conditions on a treadmill

The objective of the research was to determine the optimal location and method of attachment for accelerometer-based motion sensors, and to validate their ability to differentiate rest and increases in speed in healthy dogs moving on a treadmill. Two accelerometers were placed on a harness between the scapulae of dogs with one in a pouch and one directly attached to the harness. Two additional accelerometers were placed (pouched and not pouched) ventrally on the dog's collar. Data were recorded in 1s epochs with dogs moving in stages lasting 3 min each on a treadmill: (1) at rest, lateral recumbency, (2) treadmill at 0% slope, 3 km/h, (3) treadmill at 0% slope, 5 km/h, (4) treadmill at 0% slope, 7 km/h, (5) treadmill at 5% slope, 5 km/h, and (6) treadmill at 5% slope, 7 km/h. Only the harness with the accelerometer in a pouch along the dorsal midline yielded statistically significant increases (P<0.05) in vector magnitude as walking speed of the dogs increased (5-7 km/h) while on the treadmill. Statistically significant increases in vector magnitude were detected in the dogs as the walking speed increased from 5 to 7 km/h, however, changes in vector magnitude were not detected when activity intensity was increased as a result of walking up a 5% grade. Accelerometers are a valid and objective tool able to discriminate between and monitor different levels of activity in dogs in terms of speed of movement but not in energy expenditure that occurs with movement up hill.

Effects of daily physical activity level on the degree of sympathetic tone

BACKGROUND

Exercise is recommended for the treatment and prevention of cardiac disorders. Relaxation of the sympathetic nervous system has been considered to be one of the therapeutic mechanisms. However, the means by which the level of daily physical activity affects sympathetic activity remains unclear.

OBJECTIVE

To evaluate the effects of daily physical activity on autonomic nervous tone.

METHODS

Daily physical activity was measured for 5 or more days in 26 patients with various cardiac disorders of NYHA class 1 or 2 and in 6 healthy individuals using an intelligent calorie counter. Recumbent resting ECG was recorded for 3 minutes immediately before waking up and after going to bed using a digital ECG. Low- (Lf, 0.03-0.15 Hz) and high- (Hf, 0.15-0.45 Hz) frequency components were calculated by frequency analysis of the R-R interval, and Lf/Hf ratio was calculated as an index of sympathetic tone.

RESULTS

The average values of energy expenditure and time were 145+/-93.6 kcal/day and 47.8+/-24.3 min/day, respectively. The morning Lf/Hf ratio decreased following an increased physical activity level the day before, but increased with subsequent increase in the activity level in 65.6% of subjects. A negative correlation was observed in 34.4% of subjects, which suggested that an appropriate level of physical activity led to relaxation of sympathetic tone.

CONCLUSION

The daily level of physical activity affects sympathetic tone, and an appropriate level results in sympathetic relaxation. The results of this study provide a useful index to enable patients with cardiac disorder to perform exercise without overloading.

Evaluation of an accelerometer for at-home monitoring of spontaneous activity in dogs

OBJECTIVE

To determine the correlation between activity as measured by an accelerometer and videographic measurements of movement and mobility in healthy dogs.

ANIMALS

4 healthy dogs.

PROCEDURES

After determination that accelerometers had good agreement, 5 identical accelerometers were used simultaneously to test their output at 8 locations (rotated among collar, vest, and forelimb stocking locations) on each dog. Movement and mobility for each dog were recorded continuously with a computerized videography system for 7-hour sessions on 4 consecutive days. Accelerometer values were combined into 439 fifteen-minute intervals and compared with 3 videographic measurements of movement and mobility (distance traveled, time spent walking > 20 cm/s, and time spent changing position by > 12% of 2-dimensional surface area during 1.5 seconds).

RESULTS

96% of values compared between the most discordant pair of accelerometers were within 2 SDs of the mean value from all 5 accelerometers. All mounting locations provided acceptable correlation with videographic measurements of movement and mobility, and the ventral portion of the collar was determined to be the most convenient location.

CONCLUSIONS AND CLINICAL RELEVANCE

Use of an accelerometer was adequate for at-home activity monitoring, an important end point in clinical trials of treatment for chronic disease, and provided information about daily activity that is unattainable by other methods.

Additional Physical Activity During Cardiac Rehabilitation Leads to an Improved Heart Rate Recovery in Male Patients After Coronary Artery Bypass Grafting

BACKGROUND

Heart rate recovery (HRR) after exercise, which is thought to be a marker of vagal activity, has been reported to improve after cardiac rehabilitation (CR) with exercise in patients with coronary heart disease. The aim of this study was to determine whether or not additional physical activity outside the CR program, would accelerate improvement of the HRR in male patients after coronary artery bypass grafting (CABG).

METHODS AND RESULTS

Twenty male patients were enrolled in a supervised CR program at 2 weeks after CABG, and divided into an active group (walking >or=5,434 steps/day) or a less-active group. The time constant of HRR immediately measured after pedaling exercise was assessed at baseline and after the 2-week CR program. After completion of the CR program, the time constant of HRR improved from 439.7+/-177 s to 288.6+/-97.4 s in the active group (p<0.01), but no changes were observed in the less-active group.

CONCLUSIONS

The results suggest that additional physical activity during a CR program may lead to an improved HRR in patients after CABG. Therefore, post-CABG patients should increase their level of physical activity in addition to that in the CR to improve their cardiac autonomic control.