Validity of the ActiGraph GT1M during walking and cycling

Abstract

The ActiGraph activity monitors have developed and newer versions of the ActiGraph accelerometers (GT1M, GT3X and GT3X +) are now available, including changes in hardware and software compared to the old version (AM7164). This is problematic as most of the validation and calibration work includes the AM7164. The aims of the study were to validate the ActiGraph GT1M during level and graded walking and to assess the potential underestimation of physical activity during cycling. Data were obtained from 20 participants during treadmill walking and ergometer cycling. Energy expenditure was measured via indirect calorimetry and used as the criterion method. Activity counts were highly correlated with energy expenditure during level walking (R² = 0.82) and graded walking at 5% and 8% (R² = 0.82 and R² = 0.67, respectively). There was no linear relationship between activity counts and energy expenditure during cycling. The average activity counts for all data points during cycling was 1,157 counts per minute (CPM) (SD = 974), and mean energy expenditure was 5.0 metabolic equivalents. The GT1M is a valid tool for assessing walking across a wide range of speeds and gradients. However, there is no relationship between activity counts and energy expenditure during cycling and physical activity is underestimated by ≈73% during cycling compared to walking.     

Maximum oxygen uptake and body composition of healthy Hong Kong Chinese adult men and women aged 20 – 64 years

Abstract

The aims of the present study were to assess the maximal oxygen uptake and body composition of adult Chinese men and women, and to determine how these variables relate to age. The cross-sectional sample consisted of 196 men and 221 women aged 20 – 64 years. Maximal oxygen uptake ([Vdot]O_2max) was determined by indirect calorimetry during a maximal exercise test on an electrically braked cycle ergometer. The correlations between [Vdot]O_2max and fat mass were ?0.52 in men and ?0.58 in women. Linear regression defined the cross-sectional age-related decline in [Vdot]O_2max as 0.35 ml · kg^?1 · min^?1 · year^?1 in men and 0.30 ml · kg^?1 · min^?1 · year^?1 in women. Multiple regression analysis showed that more than 50% of this cross-sectional decline in [Vdot]O_2max was due to fat mass, lean mass, and age. Adding fat mass and lean mass to the multiple regression models reduced the age regression mass from 0.35 to 0.24 ml · kg^?1 · min^?1 · year^?1 in men and from 0.30 to 0.15 ml · kg^?1 · min^?1 · year^?1 in women. We conclude that age, fat mass, and lean mass are independent determinants of maximal oxygen uptake in Chinese adults.     

Checking In

Despite the growing popularity of women's ice hockey in North America, players continue to face limitations because of the prohibition of body checking. In this paper, we argue from a liberal feminist philosophical perspective that this prohibition reinforces existing traditional stereotypes of female athletes. Because the women's game does not incorporate checking, female ice hockey players are not afforded the same opportunity to flourish as men and experience bodily agency, which results in continued male domination of the game, therefore, indirectly reinforcing a gender hierarchy in hockey and society.     

The relationship between PE biographies and PE teaching practices of classroom teachers

The current study sought to explore the relationship between personal school physical education (PE) experiences and current PE teaching practices of classroom teachers. Questionnaires were completed by 189 teachers from 38 randomly selected schools. Additionally, semi-structured interviews of 31 classroom teachers were conducted. The results indicated that many teachers had negative memories of school PE and believed that they were not taught anything. Interestingly, teachers involved in the study held reasonably positive attitudes towards teaching PE but examination of their current teaching practices indicated that little ‘teaching’ was evident in their PE programmes. A hierarchical regression model was used to examine key predictors of PE programme quality and accounted for 32% of the variance. Personal school experiences in primary school PE, quality of preservice education and attitudes to teaching PE were established as significant predictors. A key finding of the current study was the significant relationship evident between personal school experiences in PE and current PE teaching practices which has not been previously established with classroom teachers. The implications of these findings for preservice education and professional development will be discussed.     

Step width alters iliotibial band strain during running

This study assessed the effect of step width during running on factors related to iliotibial band (ITB) syndrome. Three-dimensional (3D) kinematics and kinetics were recorded from 15 healthy recreational runners during overground running under various step width conditions (preferred and at least ± 5% of their leg length). Strain and strain rate were estimated from a musculoskeletal model of the lower extremity. Greater ITB strain and strain rate were found in the narrower step width condition (p < 0.001, p = 0.040). ITB strain was significantly (p < 0.001) greater in the narrow condition than the preferred and wide conditions and it was greater in the preferred condition than the wide condition. ITB strain rate was significantly greater in the narrow condition than the wide condition (p = 0.020). Polynomial contrasts revealed a linear increase in both ITB strain and strain rate with decreasing step width. We conclude that relatively small decreases in step width can substantially increase ITB strain as well as strain rates. Increasing step width during running, especially in persons whose running style is characterized by a narrow step width, may be beneficial in the treatment and prevention of running-related ITB syndrome.     

Assessment of theft and mutilation of information resources in selected academic libraries in Niger State

This research was conducted to assess theft and mutilation of information resources in academic libraries in the Niger State of Nigeria, the reason why users resort to theft and mutilation, measures used to steal and mutilate information resources, possible measures to stem and curb these acts in the future. The survey research method was employed using the simple random sampling technique where three academic libraries were selected from all academic libraries in Niger State. Two types of validated questionnaires were designed and administered to both staff and student users. One hundred copies of the questionnaire were administered to library staff, out of which 72 copies were returned and found usable with valid responses. One hundred and eighty copies of the questionnaires out of 250 administered to student users were returned with valid data. The findings revealed that most of the offenders are students who use various methods to perfect these acts. It was also discovered that such stolen materials were concealed in clothes, files or bags. Mutilations of materials occurred in the form of tearing pages of text materials and writing on pages of books. It equally revealed that theft and mutilation were encouraged by the lack of adequate copies of titles to meet the needs of users among others. To address these problems, certain security systems, provisions of photocopiers and the extension of library hours are recommended.     

Examining the application of Web 2.0 in medical-related organisations

Objectives: This study surveyed Web 2.0 application in three types of selected health or medical‐related organisations such as university medical libraries, hospitals and non‐profit medical‐related organisations. Methods: Thirty organisations participated in an online survey on the perceived purposes, benefits and difficulties in using Web 2.0. A phone interview was further conducted with eight organisations (26.7%) to collect information on the use of Web 2.0. Data were analysed using both quantitative and qualitative approaches. Results: Results showed that knowledge and information sharing and the provision of a better communication platform were rated as the main purposes of using Web 2.0. Time constraints and low staff engagement were the most highly rated difficulties. In addition, most participants found Web 2.0 to be beneficial to their organisations. Conclusions: Medical‐related organisations that adopted Web 2.0 technologies have found them useful, with benefits outweighing the difficulties in the long run. The implications of this study are discussed to help medical‐related organisations make decisions regarding the use of Web 2.0 technologies.     

Friction reduction using self-waxing alpine skis

A continuously waxed ski has been developed that releases a thin film of lubricant under the base of a ski. This replicates the melt water layer observed in snow skis which is caused by frictional and solar heating. The system is particularly effective on artificial (dry) slopes where skiers slide on plastic bristles rather than snow. Speeds comparable to those achieved on snow are achieved using this system and this improves the experience for the skier. Speed enhancements on plastic slopes of up to 50?% have been achieved using solutions of polyethylene glycol in water. There is speed enhancement of approximately 9?% on artificial snow and 2?% on fresh alpine snow. The latter value is highly significant as it can be the difference between winning a medal in ski competitions and finishing outside the top ten. In addition to the quantitative data, qualitative athlete perceptions were also recorded and show that a feel like snow can be achieved on artificial surfaces. Because the lubrication system is attached to the ski, it allows personal performance enhancement irrespective of a water misting system being in operation or not. The design complies with the equipment regulations of the skiing??s international governing body so it can be used in competition.     

Microstripes for transport and separation of magnetic particles

We present a simple technique for creating an on-chip magnetic particle conveyor based on exchange-biased permalloy microstripes. The particle transportation relies on an array of stripes with a spacing smaller than their width in conjunction with a periodic sequence of four different externally applied magnetic fields. We demonstrate the controlled transportation of a large population of particles over several millimeters of distance as well as the spatial separation of two populations of magnetic particles with different magnetophoretic mobilities. The technique can be used for the controlled selective manipulation and separation of magnetically labelled species.     

Bidirectional cross-sectional and prospective associations between physical activity and body composition in adolescence: birth cohort study

The aim of this study was to investigate the cross-sectional and prospective associations between physical activity and body composition in adolescence. This is a prospective study, including 4,103 adolescents belonging to the Pelotas (Brazil) 1993 birth cohort, who were followed up at the mean ages of 11.3 and 14.7 years. Subsample analyses included 511 individuals with accelerometry and deuterium dilution data at 13.3 years. Sum of skinfolds at age 11.3 years was highly correlated with skinfolds at age 14.7 years (rho = 0.74, P < 0.001). More than 85% of participants remained in the same quintile or changed by not more than one quintile during the 3.4 year period. Tracking of physical activity was considerably lower, although still significant; the correlation was 0.24 (P < 0.001) and 61.4% of the adolescents moved one or less quintiles. In fully-adjusted models, no significant cross-sectional or longitudinal associations were found between physical activity and body composition, neither in boys nor in girls. These null results were confirmed in the 511 individuals with accelerometry and deuterium data. We provide evidence of tracking of physical activity and particularly body composition during adolescence. Our results do not support the hypothesis that physical activity and fatness are strongly related in adolescents.