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Xihe Zhu and Justin A. Haegele

.74] Days 2–4 43.19 25.09 [26.84, 59.54] Note . MVPA = moderate to vigorous physical activity; CI = confidence interval; VI = visual impairment. * p  < .01. Discussion The purpose of this study was to examine reactivity to accelerometer measurement among children with visual impairments and their siblings

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Tsuyoshi Saida, Masayuki Kawada, Daijiro Kuroki, Yuki Nakai, Takasuke Miyazaki, Ryoji Kiyama and Yasuhiro Tsuneyoshi

This study aimed to clarify the effect of total knee arthroplasty (TKA) on trunk fluctuation and regularity of gait in patients with knee osteoarthritis by an accelerometer. The participants included 18 patients with knee osteoarthritis undergoing TKA. The gait at a comfortable velocity was assessed pre- and post-TKA by a triaxial accelerometer attached to the neck and lumbar regions. Measurement post-TKA was performed 4 weeks after surgery. Trunk fluctuation was estimated by the root mean square (RMS) of acceleration and RMS ratio (the ratio of RMS in each direction to the total RMS). Regularity of gait was estimated using the autocorrelation function. The results showed that TKA significantly decreased the RMS ratio in mediolateral acceleration of the neck and lumbar regions and reduced gait regularity. TKA appears to reduce compensatory trunk motion through the improvement of knee function. An assessment of trunk fluctuation using an accelerometer is useful for the clinical assessment of patients with knee osteoarthritis pre- and post-TKA.

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Kimberley S. van Schooten, Sietse M. Rispens, Petra J.M. Elders, Paul Lips, Jaap H. van Dieën and Mirjam Pijnappels

We investigated the reliability of physical activity monitoring based on trunk accelerometry in older adults and assessed the number of measured days required to reliably assess physical activity. Seventy-nine older adults (mean age 79.1 ± 7.9) wore an accelerometer at the lower back during two nonconsecutive weeks. The duration of locomotion, lying, sitting, standing and shuffling, movement intensity, the number of locomotion bouts and transitions to standing, and the median and maximum duration of locomotion were determined per day. Using data of week 2 as reference, intraclass correlations and smallest detectable differences were calculated over an increasing number of consecutive days from week 1. Reliability was good to excellent when whole weeks were assessed. Our results indicate that a minimum of two days of observation are required to obtain an ICC ≥ 0.7 for most activities, except for lying and median duration of locomotion bouts, which required up to five days.

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Akitomo Yasunaga, Hyuntae Park, Eiji Watanabe, Fumiharu Togo, Sungjin Park, Roy J. Shephard and Yukitoshi Aoyagi

The Physical Activity Questionnaire for Elderly Japanese (PAQ-EJ) is a self-administered physical activity questionnaire for elderly Japanese; the authors report here on its repeatability and direct and indirect validity. Reliability was assessed by repeat administration after 1 month. Direct validation was based on accelerometer data collected every 4 s for 1 month in 147 individuals age 65–85 years. Indirect validation against a 10-item Barthel index (activities of daily living [ADL]) was completed in 3,084 individuals age 65–99 years. The test–retest coefficient was high (r = .64–.71). Total and subtotal scores for lower (transportation, housework, and labor) and higher intensity activities (exercise/sports) were significantly correlated with step counts and durations of physical activity <3 and ≥3 METs (r = .41, .28, .53), respectively. Controlling for age and ADL, scores for transportation, exercise/sports, and labor were greater in men, but women performed more housework. Sex- and ADL- or age-adjusted PAQ-EJ scores were significantly lower in older and dependent people. PAQ-EJ repeatability and validity seem comparable to those of instruments used in Western epidemiological studies.

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Lina Engelen, Anita C Bundy, Jamie Lau, Geraldine Naughton, Shirley Wyver, Adrian Bauman and Louise Baur

Background:

To promote healthy lifestyles, we need to understand more about the patterns of children’s activities after school.

Methods:

Twenty 5- to 7-year-old children and their parents participated in this study. Parents used ‘real-time’ diaries to report children’s activities and contextual information at 3 randomly selected times per day, over 4 week days. Reporting was repeated after 13 weeks. Simultaneously children wore Actical accelerometers.

Results:

Approximately 300 simultaneous accelerometer measurements and diary entries were compared. Mean physical activity levels were highest when children engaged in activities generally considered as “active” and lowest for doing “nothing.” However, the range within activities was very large; some children who reported TV/screen time accumulated high accelerometry counts and conversely, some children were practically sedentary during organized sports. Children spent most (78%) of their after school time indoors, but the children were significantly more active outdoors than indoors [t(74.8) = 5.0, P < .001].

Conclusions:

Accelerometer data in conjunction with real-time diaries provide a more complete understanding of the value of outdoor play in increasing movement opportunities for children’s after school activities.

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Virginie Nicaise, Noe C. Crespo and Simon Marshall

Background:

Even when objective physical activity (PA) measures are preferred, many intervention studies with Latina women rely on self-reports because they are more feasible and the type and domain of PA is of interest.

Purpose:

This study examined the sensitivity and specificity of the IPAQ for detecting intervention-related changes in physical activity compared with accelerometer measurement among Latinas.

Methods:

In March 2007, a community sample of 94 women (mean age = 36.31 ± 9.1 yr; mean body mass index = 31.37 ± 7.13) participated in a 12-week pedometer-based intervention to increase moderate intensity physical activity (MPA). Participants completed the Spanish-language International Physical Activity Questionnaire (Sp-IPAQ; telephone, long form) and wore an Actigraph accelerometer for 7 days at baseline and postintervention.

Results:

Both the IPAQ and the ActiGraph accelerometer detected intervention-related increases in MPA; however, these changes were largely uncorrelated. The IPAQ did not have acceptable level of sensitivity and specificity before and after the intervention when compared with objective assessments.

Conclusions:

Data suggest that it is important to improve the sensitivity and specificity of the IPAQ with Spanish-speaking participants and further research is needed to accurately measure intervention effectiveness using self-reports of PA in Latinas.

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Niell G. Elvin, Alex A. Elvin and Steven P. Arnoczky

Modern electronics allow for the unobtrusive measurement of accelerations outside the laboratory using wireless sensor nodes. The ability to accurately measure joint accelerations under unrestricted conditions, and to correlate them with jump height and landing force, could provide important data to better understand joint mechanics subject to real-life conditions. This study investigates the correlation between peak vertical ground reaction forces, as measured by a force plate, and tibial axial accelerations during free vertical jumping. The jump heights calculated from force-plate data and accelerometer measurements are also compared. For six male subjects participating in this study, the average coefficient of determination between peak ground reaction force and peak tibial axial acceleration is found to be 0.81. The coefficient of determination between jump height calculated using force plate and accelerometer data is 0.88. Data show that the landing forces could be as high as 8 body weights of the jumper. The measured peak tibial accelerations ranged up to 42 g. Jump heights calculated from force plate and accelerometer sensors data differed by less than 2.5 cm. It is found that both impact accelerations and landing forces are only weakly correlated with jump height (the average coefficient of determination is 0.12). This study shows that unobtrusive accelerometers can be used to determine the ground reaction forces experienced in a jump landing. Whereas the device also permitted an accurate determination of jump height, there was no correlation between peak ground reaction force and jump height.

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Kathleen Simpson, Beth Parker, Jeffrey Capizzi, Paul Thompson, Priscilla Clarkson, Patty Freedson and Linda Shannon Pescatello

Background:

Little information exists regarding the psychometric properties of question 8 (Q8) of the Paffenbarger Physical Activity Questionnaire (PPAQ) to assess exercise. Thus, we conducted 2 studies to assess the validity and test–retest reliability of Q8 among adults.

Methods:

Study 1 participants (n = 419) were 44.1 ± 16.1 years of age. Validity was determined by comparing self-reported hr·d−1 in sedentary, light, moderate, and vigorous intensity physical activity (PA) and MET-hr·wk−1 on Q8 at baseline to accelerometer and health/fitness measurements using Spearman rank-order correlations. Study 2 participants (n = 217) were 44.7 ± 16.3 years of age and completed Q8 at baseline, 3 months, and 6 months. Test–retest reliability was determined using repeated measures analysis of covariance, intraclass correlations (ICCs), and standard error of the measurement (SEM).

Results:

Q8 displayed good criterion validity compared with accelerometer measurements (r = .102 to .200, P < .05) and predictive validity compared with health/fitness measurements (r = –.272 to .203, P < .05). No differences were observed in self-reported hr·d−1 in any of the PA categories at baseline, 3 months, and 6 months (ICC: 0.49 to 0.68; SEM: 1.0 to 2.0; P > .05), indicating good reliability.

Conclusion:

Q8 demonstrates adequate criterion validity, acceptable predictive validity, and satisfactory test–retest reliability and can be used in conjunction with other components of the PPAQ to provide a complete representation of exercise.

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Sarah A. Amin, Paula J. Duquesnay, Catherine M. Wright, Kenneth Chui, Christina D. Economos and Jennifer M. Sacheck

percentile as overweight, and ≥95th percentile as obese. PA: Accelerometer Measurement PA was measured by waist-worn triaxial accelerometers (ActiGraph GT3X+ and GT3X-BT models; ActiGraph, LLC, Pensacola, FL), validated and calibrated for use among children ( 27 ). Participants were outfitted at scheduled

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Anna Pulakka, Eric J. Shiroma, Tamara B. Harris, Jaana Pentti, Jussi Vahtera and Sari Stenholm

measurements of a varying true value ( Bland & Altman, 2007 ). The results are shown as mean differences and 95% limits of agreement (LOA). For Aim 1, we compared the three sleep detection algorithms to logs, as participant logs are commonly used to define sleep in 24-h accelerometer measurements. For Aim 2