Activity analysis of English premiership rugby football union refereeing

Little is known about the physiological demands placed on officials during sporting activities. The purpose of this study was to ascertain the movement activities of referees during English Premiership rugby football union matches, and to determine the frequency and duration of these activities. Nine referees who were ranked in the top 20 referees in England were videotaped during a total of 19 matches. During playback of the videotapes, a single observer coded the referees' activities into one of six distinct categories (standing, walking forwards, walking backwards, jogging, running and sprinting) using a computerized video editing system (Observer Video-Pro). The referees were timed over a 20 m distance for the modes of locomotory activity, and the average velocity of the referee for each activity was used to calculate the total distance covered in each mode of activity during matches. The total distance covered during a match was (χ ± SD) 8581 ± 668 m. The mean percentage of total playing time spent in each activity was: standing still, 37.0 ± 11.0%; walking forward, 29.5 ± 7.2%; walking backward, 9.9 ± 3.2%; jogging, 12.8 ± 3.2%; running, 9.8 ± 2.3%; and sprinting, 1.0 ± 0.4%. There were a total of 672 transitions between modes of activity during a match. The results of this study suggest that refereeing top English rugby football union matches is physically demanding. Although the major physiological load is placed on the oxygen transport system, frequent sprint bouts and the associated requirements for acceleration and deceleration impose additional metabolic demands on referees. This information may be used in the design of physical training programmes to optimize performance in referees.     

Effect of carbohydrate supplementation on simulated exercise of rugby league referees

This investigation evaluated the effectiveness of supplementing eight elite rugby league referees with a 6% maltodextrin (Md) solution whilst undertaking a simulated rugby league game. The simulation was based on motion analysis of six rugby league matches. Subjects undertook two trials of repetitive 20-m shuttle activity on an indoor track. During one trial 200 ml of Md was ingested at eight time points and in the other trial a similarly tasting placebo (Pl) was administered. A single-blind, counterbalanced design was employed. The simulation involved subjects performing four, 10-min blocks of shuttle activity before a 10-min break was instigated. Three further 10-min blocks of shuttle activity were also performed before a performance test to volitional exhaustion involving 20-m shuttles at paces varying between 55 and 95% of a pre-determined VO2max was undertaken. Timed 15-m sprints took place during each of the 10-min blocks. The rating of perceived exertion (RPE), and blood glucose and lactate concentrations were also determined throughout. The mean number of shuttles to exhaustion was significantly greater with Md ingestion than with Pl ingestion (57 +/- 19 vs. 43 + 15; p < 0.05), while the mean 15-m sprint times were significantly shorter for the Md than the Pl condition (2.40 +/- 0.09 s vs. 2.51 +/- 0.14 s; p < 0.01). The mean RPE was 5.2% lower during Md than Pl ingestion, the values being significantly different (Md: 12.07 +/- 0.32; Pl: 12.73 +/- 0.28; p < 0.01). Maltodextrin ingestion significantly elevated blood glucose levels compared with placebo (F(1,7) = 18.07: p < 0.01), although no significant differences were apparent for blood lactate levels (F(1,7) = 4.39; p > 0.05). These results highlight the beneficial effects of maltodextrin ingestion on work-rates of rugby league referees in a simulation of a game's activity. The improvement may be related to higher circulating concentrations of blood glucose.     

Exploring polynomial classifier to predict match results in football championships

Football is the team sport that mostly attracts great mass audience. Because of the detailed information about all football matches of championships over almost a century, matches build a huge and valuable database to test prediction of matches results. The problem of modeling football data has become increasingly popular in the last years and learning machine have been used to predict football matches results in many studies. Our present work brings a new approach to predict matches results of championships. This approach investigates data of matches in order to predict the results, which are win, draw and defeat. The investigated groups were different type of combinations of two by two pairs, win-draw, win-defeat and draw-defeat, of the possible matches results of each championship. In this study we employed the features obtained by scouts during a football match. The proposed system applies a polynomial algorithm to analyse and define matches results. Some machine-learning algorithms were compared with our approach, which includes experiments with information obtained from the football championships. The association between polynomial algorithm and machine learning techniques allowed a significant increase of the accuracy values. Our polynomial algorithm provided an accuracy superior to 96%, selecting the relevant features from the training and testing set.     

Dolores: a model that predicts football match outcomes from all over the world

Machine Learning - The paper describes Dolores, a model designed to predict football match outcomes in one country by observing football matches in multiple other countries. The model is a mixture...     

Effect of carbohydrate supplementation on simulated exercise of rugby league referees

This investigation evaluated the effectiveness of supplementing eight elite rugby league referees with a 6% maltodextrin (Md) solution whilst undertaking a simulated rugby league game. The simulation was based on motion analysis of six rugby league matches. Subjects undertook two trials of repetitive 20-m shuttle activity on an indoor track. During one trial 200 ml of Md was ingested at eight time points and in the other trial a similarly tasting placebo (Pl) was administered. A single-blind, counterbalanced design was employed. The simulation involved subjects performing four, 10-min blocks of shuttle activity before a 10-min break was instigated. Three further 10-min blocks of shuttle activity were also performed before a performance test to volitional exhaustion involving 20-m shuttles at paces varying between 55 and 95% of a pre-determined [Vdot]O_{2 max} was undertaken. Timed 15-m sprints took place during each of the 10-min blocks. The rating of perceived exertion (RPE), and blood glucose and lactate concentrations were also determined throughout. The mean number of shuttles to exhaustion was significantly greater with Md ingestion than with Pl ingestion (57 ± 19 vs. 43 ± 15; p < 0.05), while the mean 15-m sprint times were significantly shorter for the Md than the Pl condition (2.40 ± 0.09 s vs. 2.51 ± 0.14 s; p < 0.01). The mean RPE was ～ 5.2% lower during Md than Pl ingestion, the values being significantly different (Md: 12.07 ± 0.32; Pl: 12.73 ± 0.28; p < 0.01). Maltodextrin ingestion significantly elevated blood glucose levels compared with placebo (F(1,7) = 18.07: p < 0.01), although no significant differences were apparent for blood lactate levels (F(1,7) = 4.39; p > 0.05). These results highlight the beneficial eVects of maltodextrin ingestion on work-rates of rugby league referees in a simulation of a game?s activity. The improvement may be related to higher circulating concentrations of blood glucose.     

Effect of physical activity and air velocity on the thermal insulation of clothing

Abstract

Intrinsic thermal clothing insulation and surface air insulation were measured on human subjects by the use of indirect calorimetry. Four male clothing ensembles (0-1-1 -8 clo) and three female clothing ensembles (0-2-1-2 clo) were investigated. Using the standing position as a reference, the influence of sitting, bicycling (40r.p.m., 20 W), walking (3-75 km hour^?1) and of light packing work on the thermal insulation was studied. The influence of an air velocity of 11ms^?1 on thermal insulation during the standing and walking conditions was investigated. The results showed that: (i) intrinsic clothing insulation was maximal in the standing position. It was reduced by 8-18% in the seated position and by 30-50% during bicycling and walking. An air velocity of 11ms^?1 did not influence the intrinsic clothing insulation during walking, but decreased it by 18% in the standing position; (ii) surface air insulation varied with activity and air velocity, but not with clothing. It was increased by up to 25% in the seated position, reduced by 7-26% during bicycling and by 30-50% during walking. An air velocity of 11 ms-1 reduced the surface air insulation by 50% in the standing position and 30% during walking.     

The importance of a match in a tournament

A quantitative measure of “match importance” is useful in a number of decision problems, for example: as a metric in tournament design; for selecting matches for broadcasting; for scheduling matches in a tournament; and for assigning referees. To date measures of match importance used in such analyses have been relatively naïve. We discuss a general measure that considers the effect of a particular match on the end of tournament position, given the results of all other matches, some played, some predicted. We use logistic regression to predict matches and Monte Carlo simulation to compute the match importance measure, and apply these to soccer matches in the English Football Association Premier League.     

Cardiorespiratory strain during walking in snow with boots of different weights

In order to assess the physiological strain of different boot weights, seven male and three female subjects walked on a treadmill and a snow-field while wearing three types of boots: winter jogging boots (WJB), rubber boots (RB), and rubber safety boots (RSB), weighing (means +/- s.d.) 0.9 +/- 0.1, 1.9 +/- 0.4 and 2.5 +/- 0.2 kg, respectively During each walk the subjects wore the same clothing ensembles and moved at the same, individually determined speed. The mean (+/- s.e.) depths of the footprint impression in the snow while walking in the WJB, RB, and RSB were 26.1 +/- 1.5, 25.6 +/- 1.4 and 26.1 +/- 1.5 cm (NS), respectively. During walking on the treadmill, the means for oxygen consumption were 0.79 +/- 0.05, 0.81 +/- 0.06 and 0.83 +/- 0.04 l min-1 (NS) and in snow 2.24 +/- 0.18, 2.34 +/- 0.17 and 2.34 +/- 0.19 l min-1 (p less than 0.01) with the WJB, RB and RSB, respectively. The mean oxygen consumption levels observed during the walks averaged 23% and 65% of the subject's maximum oxygen consumption on the treadmill and in the snow-field, respectively. During the walking tests the corresponding mean heart rates were 106 +/- 4, 93 +/- 5, and 95 +/- 5 beats min-1 (p less than 0.05) on the treadmill, and 151 +/- 11, 150 +/- 11 and 151 +/- 12 beats min-1 (NS) in snow. No significant differences in ratings of perceived exertion were observed between the walking tests in snow with the three types of boots. In accordance with earlier studies, walking in snow was found to be strenuous work. In conclusion, the use of the RSB is recommended during logging work in snow, since they are known to provide greater protection than lighter boots and the increase in physiological strain experienced with RSB in this study was not appreciably greater than that with boots of lighter weight.     

A 3D virtual environment for training soccer referees

Emerging digital technologies are being used in many ways by and in particular virtual environments provide new opportunities to gain experience on real-world phenomena without having to live the actual real-world experiences. In this study, a quantitative research approach supported by expert validation interviews was conducted to determine the availability of virtual environments in the training of soccer referees. The aim is to design a virtual environment for training purposes, representing a real-life soccer stadium to allow the referees to manage matches in an atmosphere similar to the real stadium atmosphere. At this point, the referees have a chance to reduce the number of errors that they make in real life by experiencing difficult decisions that they encounter during the actual match via using the virtual stadium. In addition, the decisions and reactions of the referees during the virtual match were observed with the number of different fans in the virtual stadium to understand whether the virtual stadium created a real stadium atmosphere for the referees. For this evaluation, Presence Questionnaire (PQ) and Immersive Tendencies Questionnaire (ITQ) were applied to the referees to measure their involvement levels. In addition, a semi-structure interview technique was utilized in order to understand participants’ opinions about the system. These interviews show that the referees have a positive attitude towards the system since they can experience the events occurred in the match as a first person instead of watching them from camera as a third person. The findings of current study suggest that virtual environments can be used as a training tool to increase the experience levels of the soccer referees since they have an opportunity to decide about the positions without facing the real-world risks.     

A single tri-axial accelerometer-based real-time personal life log system capable of human activity recognition and exercise information generation

Recording a personal life log (PLL) of daily activities in a ubiquitous environment is an emerging application of information technology. In this work, we present a single tri-axial accelerometer-based PLL system capable of human activity recognition and exercise information generation. Our PLL system exhibits two main functions: activity recognition and exercise information generation. For activity recognition, the system first recognizes a state of daily activities based on the statistical and spectral features of the accelerometer signals. An activity within the recognized state is then recognized using a set of augmented features, including autoregressive coefficients, signal magnitude area, and tilt angle, via linear discriminant analysis and hierarchical artificial neural networks. Upon the recognition of each activity, the system further estimates exercise information that includes energy expenditure based on metabolic equivalents, stride length, step count, walking distance, and walking speed. Our PLL system operates in real-time, and the life log information it generates is archived in a daily log database. We have validated our PLL system for six daily activities (i.e., lying, standing, walking, going-upstairs, going-downstairs, and driving) via subject-independent and subject-dependent recognition on a total of twenty subjects, achieving an average recognition accuracy of 94.43 and 96.61%, respectively. Our results demonstrate the feasibility of a portable real-time PLL system that could be used for u-lifecare and u-healthcare services in the near future.     

Aerobic and anaerobic profiles, heart rate and match analysis in older soccer players

The aim of the present study was to provide aerobic (maximal oxygen consumption--VO2max) and anaerobic [jump tests: counter-movement jump (CMJ) and bounce jump (BJ); and running tests: 10 m sprint and 10 m dribbling the ball (10 mDB)] profiles of older soccer players (n = 12), and heart rate (HR), blood lactate accumulation (La) and match analysis (individual motor activity and team behaviour) aspects of a soccer match. The maximal aerobic test values were: HRmax, 154 +/- 14 beat min(-1); maximal power, 160 +/- 24 W; VO2peak, 36.3 +/- 11.3 ml kg(-1) min(-1); peak La, 8.2 +/- 1.8 mM. Jump test values were: CMJ, 21.2 +/- 4.5 cm; BJ, 17.3 +/- 4.8 cm. Running performances were: 10 m sprint, 2.06 +/- 0.36 s; 10 mDB, 2.17 +/- 0.21 s. Running showed similar values in the two halves (first half, 82%; second half, 88%), while walking lasted longer during the second half. Regarding the technical aspects of the match, 42% of the consecutive passes made in possession of the ball exceeded three passes, indicating that their play was structured in a cooperative manner. Older soccer players succeeded in maintaining good aerobic and anaerobic physical capability.     

Correlates of the shift in heart rate variability with postures and walking by time-frequency analysis

Heart rate (HR) variability derived from electrocardiogram (ECG) can be used to assess the function of the autonomic nervous system. HR exhibits various characteristics during different physical activities attributed to the altered autonomic mediation, where it is also beneficial to reveal the autonomic shift in response to physical-activity change. In this paper, the physical-activity-related HR behaviors were delineated using a portable ECG and body acceleration recorder based on a personal digital assistant and the smoothed pseudo Wigner-Ville distribution. The results based upon eighteen subjects performing four sequential 5-min physical activities (supine, sitting, standing and spontaneous walking) showed that the high-frequency heartbeat fluctuations during supine and sitting were significantly larger than during standing, and that the ratio of low- to high-frequency fluctuation during standing was significantly higher than during supine and sitting. This could be linked with the parasympathetic predominance during supine and sitting, and a shift to sympathetic dominance while standing. During spontaneous walking, the high-frequency fluctuation was significant lower than during supine. The low- to high-frequency ratio decreased significantly from standing to spontaneous walking, which may imply an increased vagal predominance (autonomic effect) or an increased respiratory activity (mechanical effect).     

A biomechanical analysis of anterior load carriage

Front load carriage is a common occupational task in some industries (e.g. agriculture, construction), but, as compared to lifting tasks, relatively little research has been conducted on the biomechanical loading during these activities. The focus of this study was to explore the low back biomechanics during these activities and, specifically, to examine the effects of load height and walking speed on trunk muscle activity and trunk posture. Eleven male participants participated in two separate front load-carriage experiments. The first experiment called for carrying a barbell (with weight corresponding to 20% of elbow flexion strength) at three heights (knuckle height, elbow height and shoulder height) at a constant horizontal distance from the spine. The second experiment called for participants to carry a bucket of potatoes weighing 14 kg at the same three heights, but with no further restrictions in technique. In both experiments, the participants performed this task while either standing still or walking at a self-selected speed. As they performed these tasks, the activity levels of the right-side muscle of the rectus abdominis, external oblique, biceps brachii, anterior deltoid and three levels (T9, T12 and L3) of the erector spinae were sampled. Mid-sagittal plane trunk posture was also quantified using three magnetic field-based motion sensors at T9, T12 and L3. The results showed a significant effect of both walking speed and load height on trunk posture and trunk muscle activity levels in both the barbell and bucket experiments. In the barbell experiment, the walking trials generated 43% more trunk muscle activity than the standing trials. Trials at shoulder height produced 11% more muscle activity than trials at elbow height in the T9 erector spinae muscles and 71% more muscle activity in the anterior deltoid. In the bucket experiment, trunk muscle activity responded in a similar fashion, but the key result here was the quantification of the natural hyperextension posture of the spine used to balance the bucket of potatoes. These results provide insight into muscle activation patterns in dynamic settings, especially (load) carrying biomechanics, and have implications in industrial settings that require workers to carry loads in front of their bodies.     

A biomechanical analysis of anterior load carriage

Front load carriage is a common occupational task in some industries (e.g. agriculture, construction), but, as compared to lifting tasks, relatively little research has been conducted on the biomechanical loading during these activities. The focus of this study was to explore the low back biomechanics during these activities and, specifically, to examine the effects of load height and walking speed on trunk muscle activity and trunk posture. Eleven male participants participated in two separate front load-carriage experiments. The first experiment called for carrying a barbell (with weight corresponding to 20% of elbow flexion strength) at three heights (knuckle height, elbow height and shoulder height) at a constant horizontal distance from the spine. The second experiment called for participants to carry a bucket of potatoes weighing 14 kg at the same three heights, but with no further restrictions in technique. In both experiments, the participants performed this task while either standing still or walking at a self-selected speed. As they performed these tasks, the activity levels of the right-side muscle of the rectus abdominis, external oblique, biceps brachii, anterior deltoid and three levels (T9, T12 and L3) of the erector spinae were sampled. Mid-sagittal plane trunk posture was also quantified using three magnetic field-based motion sensors at T9, T12 and L3. The results showed a significant effect of both walking speed and load height on trunk posture and trunk muscle activity levels in both the barbell and bucket experiments. In the barbell experiment, the walking trials generated 43% more trunk muscle activity than the standing trials. Trials at shoulder height produced 11% more muscle activity than trials at elbow height in the T9 erector spinae muscles and 71% more muscle activity in the anterior deltoid. In the bucket experiment, trunk muscle activity responded in a similar fashion, but the key result here was the quantification of the natural hyperextension posture of the spine used to balance the bucket of potatoes. These results provide insight into muscle activation patterns in dynamic settings, especially (load) carrying biomechanics, and have implications in industrial settings that require workers to carry loads in front of their bodies.     

Walk the talk: coordinating gesture with locomotion for conversational characters

Communicative behaviors are a very important aspect of human behavior and deserve special attention when simulating groups and crowds of virtual pedestrians. Previous approaches have tended to focus on generating believable gestures for individual characters and talker‐listener behaviors for static groups. In this paper, we consider the problem of creating rich and varied conversational behaviors for data‐driven animation of walking and jogging characters. We captured ground truth data of participants conversing in pairs while walking and jogging. Our stylized splicing method takes as input a motion captured standing gesture performance and a set of looped full body locomotion clips. Guided by the ground truth metrics, we perform stylized splicing and synchronization of gesture with locomotion to produce natural conversations of characters in motion. Copyright © 2016 John Wiley & Sons, Ltd.     

Physical activity classification in free-living conditions using smartphone accelerometer data and exploration of predicted results

In recent decades, decreasing physical activity has emerged as one of the major issues affecting human health since people increasingly engaged in sedentary behavior in their homes and workplaces. In physical activity research, using GPS trajectories and advanced GIS methods has a potential for greatly enhancing our understanding of the association between objectively measured moderate and vigorous physical activity and physical and social environments. Relying only on objectively measured physical activity intensity, however, ignores the role of different places and types of physical activity on people's health outcomes. The aim of this study is to propose an approach to classifying physical activity in free-living conditions for physical activity research using published smartphone accelerometer data. Random forest and gradient boosting are used to predict jogging, walking, sitting, and standing. Generated training models based on the two classifiers are tested on accelerometer data collected from the smartphones of two subjects in free-living conditions. GPS trajectories with predicted physical activity labels are visually explored on a map to offer new insight on the assessment of the predicted results of daily activities and the identification of any difference in the results between random forest and gradient boosting. The findings of this study indicate that random forest and gradient boosting enable accurate physical activity classification in free-living conditions. GPS trajectories linked with predicted labels on a map assist the visual exploration of the erroneous prediction in daily activities including in-vehicle activities.     

Referee assignment in the Chilean football league using integer programming and patterns

This article uses integer linear programming to address the referee assignment problem in the First Division of the Chilean professional football league. The proposed approach considers balance in the number of matches each referee must officiate, the frequency of each referee being assigned to a given team, the distance each referee must travel over the course of a season, and the appropriate pairings of referee experience or skill category with the importance of the matches. Two methodologies are studied, one traditional and the other a pattern‐based formulation inspired by the home‐away patterns for scheduling season match calendars. Both methodologies are tested in real‐world and experimental instances, reporting results that improve significantly on the manual assignments. The pattern‐based formulation attains major reductions in execution times, solving real instances to optimality in just a few seconds, while the traditional one takes anywhere from several minutes to more than an hour.     

基于WLAN接收信号强度特征的室内活动识别

针对主流的活动感知技术依赖于专业测量设备,难以广泛部署与使用的问题,提出一种基于现有WiFi热点接收信号强度特征的活动识别技术。利用机器学习算法对实时接收到的WiFi信号强度特征进行分类,通过特征匹配识别用户当前活动。实验结果显示,所提算法能够以80%以上概率判断室内是否有人,以95%以上概率判断室内的人处于什么状态,并以80%的概率识别人的运动方向。所提算法所需信号广泛存在,可有效识别室内活动,具有低功耗、高精度的优点。     

On the use of ensemble of classifiers for accelerometer-based activity recognition

Activity recognition aims to detect the physical activities such as walking, sitting, and jogging performed by humans. With the widespread adoption and usage of mobile devices in daily life, several advanced applications of activity recognition were implemented and distributed all over the world. In this study, we explored the power of ensemble of classifiers approach for accelerometer-based activity recognition and built a novel activity prediction model based on machine learning classifiers. Our approach utilizes from J48 decision tree, Multi-Layer Perceptrons (MLP) and Logistic Regression techniques and combines these classifiers with the average of probabilities combination rule. Publicly available activity recognition dataset known as WISDM (Wireless Sensor Data Mining) which includes information from thirty six users was used during the experiments. According to the experimental results, our model provides better performance than MLP-based recognition approach suggested in previous study. These results strongly suggest researchers applying ensemble of classifiers approach for activity recognition problem.     

Walking on ballast impacts balance

Railroad workers often perform daily work activities on irregular surfaces, specifically on ballast rock. Previous research and injury epidemiology have suggested a relationship between working on irregular surfaces and postural instability. The purpose of this study was to examine the impact of walking on ballast for an extended duration on standing balance. A total of 16 healthy adult males walked on a 7.62 m × 4.57 m (25 ft × 15 ft) walking surface of no ballast (NB) or covered with ballast (B) of an average rock size of about 1 inch for 4 h. Balance was evaluated using dynamic posturography with the NeuroCom^® Equitest System^? prior to experiencing the NB or B surface and again every 30 min during the 4 h of ballast exposure. Dependent variables were the sway velocity and root-mean-square (RMS) sway components in the medial–lateral and anterior–posterior directions. Repeated measures ANOVA revealed statistically significant differences in RMS and sway velocity between ballast surface conditions and across exposure times. Overall, the ballast surface condition induced greater sway in all of the dynamic posturography conditions. Walking on irregular surfaces for extended durations has a deleterious effect on balance compared to walking on a surface without ballast. These findings of changes in balance during ballast exposure suggest that working on an irregular surface may impact postural control.