Field tested milliliter-scale blood filtration device for point-of-care applications

In this paper, we present a low cost and equipment-free blood filtration device capable of producing plasma from blood samples with mL-scale capacity and demonstrate its clinical application for hepatitis B diagnosis. We report the results of in-field testing of the device with 0.8–1 ml of undiluted, anticoagulated human whole blood samples from patients at the National Hospital for Tropical Diseases in Hanoi, Vietnam. Blood cell counts demonstrate that the device is capable of filtering out 99.9% of red and 96.9% of white blood cells, and the plasma collected from the device contains lower red blood cell counts than plasma obtained from a centrifuge. Biochemistry and immunology testing establish the suitability of the device as a sample preparation unit for testing alanine transaminase (ALT), aspartate transaminase (AST), urea, hepatitis B “e” antigen (HBeAg), hepatitis B “e” antibody (HBe Ab), and hepatitis B surface antibody (HBs Ab). The device provides a simple and practical front-end sample processing method for point-of-care microfluidic diagnostics, enabling sufficient volumes for multiplexed downstream tests.     

Validation of Self-Report Measures of Physical Activity

Abstract

Accurate measurement of physical activity is fundamentally important in epidemiological research of physical activity behavior. A widely used telephone-based physical activity questionnaire was compared with other methods of administration and objective measures (pedometers and accelerometers) among 80 adults (43 women). The telephone questionnaire was comparable to both the self-administered form and international telephone-administered equivalent. Although moderate correlation coefficients with objective measures supported the use of the questionnaire, wide prediction intervals generated using Bland Altman methods highlighted large discrepancies between the measures, particularly in the moderate intensity category. These findings illustrate the limitations of correlation coefficients in validation studies and the inaccuracy of self-report questionnaires in measuring physical activity.     

Anthropometric fractionation of body mass: Matiegka revisited

In a group of 699 Belgian nursing professionals, we estimated body composition using the four-component anthropometric model, relying on the equations originally formulated by Matiegka in 1921 and later revised by Drinkwater and colleagues. We estimated muscle mass using the more recent formula proposed by Martin and co-workers. A discrepancy was noted between estimated total body mass and 'assessed' mass, suggesting erroneous estimations of the components.     

The relationship between functional potential and field performance in elite female wheelchair basketball players

The functional classification system for wheelchair basketball is based on an analysis of the players' functional resources through field-testing and game observation. Under this system, players are assigned a score of 1 to 4.5. The aim of this study was to determine if the wheelchair basketball player classification system reflects the existing differences in performance of elite female players. During the World Championship for Wheelchair Basketball in Sydney 1998, eight teams were videotaped for three 40-min games for a total of 120?min per team. Fifty-nine female players (Class I [1 and 1.5 points] n?=?12; Class II [2 and 2.5 points] n?=?20; Class III [3 and 3.5 points] n?=?13; Class IV [4 and 4.5 points] n?=?14) were retained for a detailed performance analysis by means of the Comprehensive Basketball Grading System (CBGS). Two-way analysis of variance showed high point players to perform better compared with low point players for the majority of variables determining the quality of game performance. A lack of significant differences between two adjacent classes was explained on the basis of the methodological approach, the class–position relationship in this sample, and the performance level of women's wheelchair basketball. We conclude that the performance of elite female wheelchair basketball players is dependent on functional ability.     

Distinguishing Perceived Competence and Self-Efficacy: An Example From Exercise

This article examined the conceptual and statistical distinction between perceived competence and self-efficacy. Although they are frequently used interchangeably, it is possible that distinguishing them might assist researchers in better understanding their roles in developing enduring adaptive behavior patterns. Perceived competence is conceived in the theoretical framework of self-determination theory and self-efficacy is conceived in the theoretical framework of social-cognitive theory. Purpose: The purpose of this study was to empirically distinguish perceived competence from self-efficacy for exercise. Method: Two studies evaluated the independence of perceived competence and self-efficacy in the context of exercise. Using 2 extant instruments with validity and reliability evidence in exercise contexts, the distinctiveness of the 2 constructs was assessed in 2 separate samples (n = 357 middle-aged sedentary adults; n = 247 undergraduate students). Results: Confirmatory factor analysis supported the conceptual and empirical distinction of the 2 constructs. Conclusions: This study supports the conceptual and statistical distinction of perceived competence from perceived self-efficacy. Applications of these results provide a rationale for more precise future theorizing regarding their respective roles in supporting initiation and maintenance of health behaviors.     

An empirical basis for route choice in cycling

We used data from international cycle stage races to examine a rule for cyclists that is similar to Naismith's rule. Naismith's rule is used by walkers to estimate travel times for routes involving climb (i.e. the vertical distance component of a route). The rule is also used in route choice decision-making to compare differing, competing routes. We developed such a rule for use in cycling events, and also considered an extension of the climb-distance rule to take account of the effect of type of terrain or rideability. A simple analysis of the data suggests that 1?m of vertical travel on a bicycle can be considered to be equivalent to approximately 8?m of horizontal travel. Thus the equivalent distance of a route may be calculated by taking its horizontal distance component and adding eight times its vertical distance component. The result obtained was shown to be in accord with mathematical models that relate cycling power to speed and gradient. An index that considers the effect of terrain is also reported, and incorporated into an equivalent distance model. Tentative values for the terrain or rideability index are suggested, and we argue that a distance of 1?km over good off-road terrain is equivalent to a distance of 2?km on-road, and that a distance of 1?km over poor off-road terrain is equivalent to a distance of 4?km on-road.     

Inter-individual differences in stride frequencies during running obtained from wearable data

ABSTRACT

The purpose of the present study was to identify factors that underlie differences among runners in stride frequency (SF) as a function of running speed. Participants (N = 256; 85.5% males and 14.5% females; 44.1 ± 9.8 years; 181.4 ± 8.4 cm; 75.3 ± 10.6 kg; mean ± SD) shared their wearable data (?Garmin Inc). Individual datasets were filtered to obtain representative relationships between stride frequency (SF) and speed per individual, representing in total 16.128 h of data. The group relationship between SF (72.82 to 94.73 strides · min^?1) and running speed (V) (from 1.64 to 4.68 m · s^?1) was best described with SF = 75.01 + 3.006 V. A generalised linear model with random effects was used to determine variables associated with SF. Variables and their interaction with speed were entered in a stepwise forward procedure. SF was negatively associated with leg length and body mass and an interaction of speed and age indicated that older runners use higher SF at higher speed. Furthermore, run frequency and run duration were positively related to SF. No associations were found with injury incidence, athlete experience or performance. Leg length, body mass, age, run frequency and duration were associated with SFs at given speeds.

KEY POINTS

• On a group level, stride frequency can be described as a linear function of speed: SF (strides · min^?1) = 75.01+ 3.006·speed (m · s^?1) within the range of 1.64 to 4.68 m · s^?1.

• On an individual level, the SF-speed relation is best described with a second order polynomial.

• Leg length and body mass were positively related to stride frequency while age was negatively related to stride frequency.

• Run frequency and run duration were positively related to stride frequency, while running experience, performance and injury incidence were unrelated.

     

Feasibility of eyes open alpha power training for mental enhancement in elite gymnasts

Abstract

This study focuses on a novel, easy to use and instruction-less method for mental training in athletes. Previous findings suggest that particular mental capacities are needed for achieving peak performance; including attentional control, focus, relaxation and positive affect. Electroencephalography (EEG) alpha brain activity has been associated with neural inhibition during processes of selective attention, for improving efficiency in information processing. Here we hypothesised that eyes open alpha power training by music teaches athletes to (1) learn to self-regulate their brain activity, and (2) learn to increase their baseline alpha power, herewith improving mental capacities such as focusing the allocation of attention. The study was double-blind and placebo-controlled. Twelve elite gymnasts were either given eyes open alpha power training or random beta power training (controls). Results indicate small improvements in sleep quality, mental and physical shape. In our first attempt at getting a grip on mental capacities in athletes, we think this novel training method can be promising. Because gymnastics is one of the most mentally demanding sports, we value even small benefits for the athlete and consider them indicative for future research.     

Spike jump biomechanics in male versus female elite volleyball players

ABSTRACT

There are well-known biological differences between women and men, especially in technical-coordinative variations that contribute to sex differences in performance of complex movements like the most important offensive action in volleyball, the spike jump. The aim of this study was to investigate sex-dependent performance and biomechanical characteristics in the volleyball spike jump. Thirty female and male sub-elite volleyball players were analysed while striking a stationary ball with maximal spike jump height. Twelve MX13 Vicon cameras with a cluster marker set, two AMTI force plates, surface EMG, and a Full-Body 3D model in Visual3D were used. Main findings include sex differences (P< .05) in jump height (pη² = .73), approach [speed (pη² = .61), step length], transition strategy [plant angle, neuromuscular activation (pη² = .91), horizontal force maxima and impulses], acceleration distances [centre of mass displacement (pη² = .21), minimal knee and hip angles], use of torso and arms [incline, angular velocity (pη² = .23)]. Correlations support that the results cannot be explained fully by strength and power differences between sexes but represent the product of technical-coordinative variations. Their relevance is acknowledged for both sexes and numerous performance determinants displayed sex differences. The integration of such attributes into sex-specific training seems promising but its effect requires further investigation.     

Physical Self-Concept and Strength Changes in College Weight Training Classes

Abstract

The criteria generally accepted for constructing attitude scales were followed in the construction of each of these two scales of attitude toward physical education. Standards of equivalence were also set up and followed in “equating” the two forms. The forms are proposed for use in appraising attitude changes resulting from brief experiences such as listening to a talk on physical education, watching a demonstration, viewing a film, or taking part in some activity. The two thirty-statement forms are given at the end of the article.