Change in running kinematics after cycling are related to alterations in running economy in triathletes

Emerging evidence suggests that cycling may influence neuromuscular control during subsequent running but the relationship between altered neuromuscular control and run performance in triathletes is not well understood. The aim of this study was to determine if a 45 min high-intensity cycle influences lower limb movement and muscle recruitment during running and whether changes in limb movement or muscle recruitment are associated with changes in running economy (RE) after cycling. RE, muscle activity (surface electromyography) and limb movement (sagittal plane kinematics) were compared between a control run (no preceding cycle) and a run performed after a 45 min high-intensity cycle in 15 moderately trained triathletes. Muscle recruitment and kinematics during running after cycling were altered in 7 of 15 (46%) triathletes. Changes in kinematics at the knee and ankle were significantly associated with the change in VO₂ after cycling (p < 0.05). The change in ankle angle at foot contact alone explained 67.1% of the variance in VO₂. These findings suggest that cycling does influence limb movement and muscle recruitment in some triathletes and that changes in kinematics, especially at the ankle, are closely related to alterations in running economy after cycling.

Visual perception of movement kinematics and the acquisition of "action prototypes"

Recognizing a class of movements as belonging to a "nominal" action category, such as walking, running, or throwing, is a fundamental human ability. Three experiments were undertaken to test the hypothesis that common ("prototypical") features of moving displays could be learned by observation. Participants viewed moving stick-figure displays resembling forearm flexion movements in the saggital plane. Four displays (presentation displays) were first presented in which one or more movement dimensions were combined with 2 respective cues: direction (up, down), speed (fast, slow), and extent (long, short). Eight test displays were then shown, and the observer indicated whether each test display was like or unlike those previously seen. The results showed that without corrective feedback, a single cue (e.g., up or down) could be correctly recognized, on average, with the proportion correct between .66 and .87. When two cues were manipulated (e.g., up and slow), recognition accuracy remained high, ranging between .72 and .89. Three-cue displays were also easily identified. These results provide the first empirical demonstration of action-prototype learning for categories of human action and show how apparently complex kinematic patterns can be categorized in terms of common features or cues. It was also shown that probability of correct recognition of kinematic properties was reduced when the set of 4 presentation displays were more variable with respect to their shared kinematic property, such as speed or amplitude. Finally, while not conclusive, the results (from 2 of the 3 experiments) did suggest that similarity (or "likeness") with respect to a common kinematic property (or properties) is more easily recognized than dissimilarity.

Neuromuscular control and running economy is preserved in elite international triathletes after cycling

Running is the most important discipline for Olympic triathlon success. However, cycling impairs running muscle recruitment and performance in some highly trained triathletes; though it is not known if this occurs in elite international triathletes. The purpose of this study was to investigate the effect of cycling in two different protocols on running economy and neuromuscular control in elite international triathletes. Muscle recruitment and sagittal plane joint angles of the left lower extremity and running economy were compared between control (no preceding cycle) and transition (preceded by cycling) runs for two different cycle protocols (20-minute low-intensity and 50-minute high-intensity cycles) in seven elite international triathletes. Muscle recruitment and joint angles were not different between control and transition runs for either cycle protocols. Running economy was also not different between control and transition runs for the ow-intensity (62.4 ^ 4.5 vs. 62.1 ^ 4.0 ml/min/kg, p . 0.05) and high-intensity (63.4 ^ 3.5 vs. 63.3 ^ 4.3 ml/min/kg, p . 0.05) cycle protocols. The results of this study demonstrate that both low- and high-intensity cycles do not adversely influence neuromuscular control and running economy in elite international triathletes.

Altered movement patterns but not muscle recruitment in moderately trained triathletes during running after cycling

Previous studies have shown that cycling can directly influence neuromuscular control during subsequent running in some highly trained triathletes, despite these triathletes' years of practice of the cycle-run transition. The aim of this study was to determine whether cycling has the same direct influence on neuromuscular control during running in moderately trained triathletes. Fifteen moderately trained triathletes participated. Kinematics of the pelvis and lower limbs and recruitment of 11 leg and thigh muscles were compared between a control run (no prior exercise) and a 30 min run that was preceded by a 15 min cycle (transition run). Muscle recruitment was different between control and transition runs in only one of 15 triathletes (<7%). Changes in joint position (mean difference of 3°) were evident in five triathletes, which persisted beyond 5 min of running in one triathlete. Our findings suggest that some moderately trained triathletes have difficulty reproducing their pre-cycling movement patterns for running initially after cycling, but cycling appears to have little influence on running muscle recruitment in moderately trained triathletes.

Running in a minimalist and lightweight shoe is not the same as running barefoot : a biomechanical study

Aim The purpose of this study was to determine the changes in running mechanics that occur when highly trained runners run barefoot and in a minimalist shoe, and specifically if running in a minimalist shoe replicates barefoot running.

Methods Ground reaction force data and kinematics were collected from 22 highly trained runners during overground running while barefoot and in three shod conditions (minimalist shoe, racing flat and the athlete's regular shoe). Three-dimensional net joint moments and subsequent net powers and work were computed using Newton-Euler inverse dynamics. Joint kinematic and kinetic variables were statistically compared between barefoot and shod conditions using a multivariate analysis of variance for repeated measures and standardised mean differences calculated.

Results There were significant differences between barefoot and shod conditions for kinematic and kinetic variables at the knee and ankle, with no differences between shod conditions. Barefoot running demonstrated less knee flexion during midstance, an 11% decrease in the peak internal knee extension and abduction moments and a 24% decrease in negative work done at the knee compared with shod conditions. The ankle demonstrated less dorsiflexion at initial contact, a 14% increase in peak power generation and a 19% increase in the positive work done during barefoot running compared with shod conditions.

Conclusions Barefoot running was different to all shod conditions. Barefoot running changes the amount of work done at the knee and ankle joints and this may have therapeutic and performance implications for runners.

Coaches' perceptions of golf swing kinematics

Using a computer-based videotape analysis system, a randomized series of golf swings was presented to 10 professional and 10 amateur golf coaches in an attempt to determine differences m their internal model of golf swing kinematics. A global measure was obtained by having coaches independently inspect the swings of eight golfers and estimate their golf handicaps. A micro level of analysis was undertaken by requiring participants to indicate what they considered to be 'ideal' swing characteristics using 17 predetermined limb, club, and body position angles for various phases of the swing Videotaped swings for a highly skilled and beginner level golfer were used for this task. Although the training requirements for professional coaches are much more demanding and their playing ability higher, evidence of internal model differences was not found in the handicap estimation task. It was also established that a golfer's swing may be perceived to have deficiencies but still produce sufficient accuracy to engender a low handicap On the second task, only one of the 17 estimated swing angles showed a significant difference between the coach groups. When, however, the two coach groups indicated their preferred angles for the highly skilled golfer and the beginner, 6 of the 17 angles were significantly different. The implications of these findings are that the two coach groups had similar ability to identify fundamental characteristics of the golf swing, but their model of the ideal swing was influenced by the observed golfer's skill level.

Cell division protein ftsZ: running rings around bacteria, chloroplasts and mitochondria

Of all the proteins involved in prokaryotic cell division FtsZ is one of the earliest acting and most widely distributed, being found in all but a few species. We discuss several recent discoveries of FtsZ in eukaryotic cells and the protein’s role in the division of chloroplasts and mitochondria, organelles that are of bacterial origin.

Discourses of deception: cheating in professional running

Cheating, it is claimed, is anathema to sport. But is this the case? In this paper it is argued that cheating is integral to modern sport, that the model of sport as 'fair play' is simply an ideological guise of amateurism. The paper focuses on the sport of professional running which, since its origins in the eighteenth century, has been a gambling sport. Strategies involving cheating to manipulate wins, or losses, have featured in this sport as ways of increasing the probability of striking successful wagers. Such strategies are an accepted part of professional running: participants anticipate and expect others to be playing it in this way. However, a distinction is made between what is referred to in the paper as 'clean' cheating and 'dirty' cheating. The former is an accepted way of the sport, the latter occurs but is deprecated. The paper explores these different forms of cheating and the athletes' responses to them. Through a focus on the discourses of success in capitalist society, a model of cheating is developed to interpret such practices. Within the context of professional running, a working class sport, it is argued that, given the habitus of its practitioners, 'success' may be measured in terms of monetary gains and the 'kick-on' in life that these might provide. Cheating practices may serve to enhance the probability of success and social mobility. Given the relatively short career spans of sports people and the costs involved in developing the requisite skills, cheating may promote success and establish a financial base for post-sport careers. The paper concludes that cheating in sport can be anticipated as a feature of an acquisitive capitalist society.

`Just give me someone who can hit the ground running`: an investigation into the job-ready public relations graduate

Public relations educators perform an academic and vocational balancing act. Employers demand graduates with developed vocational skills. In the meantime, academics strive to provide students with work skills as well as solid theoretical base, and to also address emerging issues. This paper uses a case study in Geelong, Victoria to examine what Australian regional employers see as desirable attributes in public relations graduates. It then explores how educators address the needs of the employers as well as the needs of the public relations profession.

Games within games: gambling and trickery in professional running

Professional running is an overtly gambling sport in which a clear objective is to maximise winnings from the bookmakers, which is achieved through a careful concealment of a runner’s ability. Professional runners seldom win more than one significant race. Races are deliberately lost until runners acquire a sufficiently lenient handicap to significantly improve their chances of winning a race of their choosing. Successes, kudos and identities in this sport are evaluated from the cleverness of the win, largely measured by the trainer’s effectiveness in executing a gambling coup. The money prizes given to runners may be significantly bettered from gambling winnings and making the most of these is the major emphasis for most successful runners and trainers. Drawing from an ethnographic study of this sport in Australia, the paper argues that the gambling strategies of runners and trainers can be understood as zero-sum games.

High-precision five-axis machine for high-speed material processing using linear motors and parallel-serial kinematics

The paper describes some details of the mechanical and kinematics design of a five-axis mechanism. The design has been utilized to physically realize an industrial-scale five-axis milling machine that can carry a three KW spindle. However, the mechanism could be utilized in other material processing and factory automation applications. The mechanism has five rectilinear joints/axes. Two of these axes are arranged traditionally, i.e. in series, and the other three axes utilize the concept of parallel kinematics. This combination results in a design that allows three translational and two rotational two-mode degrees of freedom (DOFs). The design provides speed, accuracy and cost advantages over traditional five-axis machines. All axes are actuated using linear motors.

Asymmetrical three-DOFs rotational-translational parallel-kinematics mechanisms based on lie group theory

The paper introduces four families of three-DOFs translational-rotational Parallel-Kinematics Mechanisms (PKMs) as well as the mobility analysis of such families using Lie group theory. Two of these families are mechanisms with one-rotational two-translational degrees of freedom (DOFs) and each of the other two has one-translational two-rotational DOFs. Four novel mechanisms are presented and discussed as representatives of these four families. Although these mechanisms are asymmetric, the components used to realise them are very similar and, hence, there is no great departure from the favourable modularity of parallel-kinematics mechanisms.