Arm coordination symmetry and breathing effect in front crawl

This study analysed the relationships among arm coordination symmetry, motor laterality and breathing laterality during a 100-m front crawl, as a function of expertise. Ten elite swimmers (G1), 10 mid-level swimmers (G2), and 8 non-expert swimmers (G3) composed three skill groups, which were distinguished by velocity, stroke rate, stroke length, breathing frequency (BF) and the mean number of strokes between two breaths - the stroke breath (SB) - over a 100-m front crawl. Four stroke phases were identified by video analysis (catch, pull, push and recovery) and the index of coordination (IdC) measured the lag time between the propulsive phases of the two arms. The three modes of coordination are catch-up (IdC<0%), opposition (IdC=0%) and superposition (IdC>0%). The IdC was established as the mean of IdC1 and IdC2, which measured the lag time between the propulsive phases of the left and right arms, respectively. The coordination symmetry was analysed by comparing IdC1 and IdC2, and the breathing effect was studied by distinguishing IdC1 (and IdC2) with and without breathing. Motor laterality was determined by an adaptation of the Edinburgh Handedness Inventory. Breathing laterality was determined by a questionnaire and observation during the 100-m trial. Most of the front crawl swimmers showed asymmetric arm coordination, with propulsive discontinuity on one side and propulsive superposition on the other. This asymmetry was most often related to breathing laterality (a preferential breathing side for a unilateral breathing pattern) and motor laterality (arm dominance), with different profiles noted. More than the breathing laterality itself, the breathing actions of the non-expert swimmers amplified their asymmetric coordination on the breathing side. Conversely, the elite swimmers, who had higher and more stable spatial-temporal parameters (velocity and stroke lengths), a high coordination value (IdC) and lower breathing frequency (BF), managed their race better than the less proficient swimmers and their asymmetric arm coordination was not disturbed by breathing actions. By determining the dominant arm and the preferential breathing side, the coach can obtain a swimmer profile that allows both coach and swimmer to better understand and respond to excessive coordination asymmetry.     

Entwicklung und Stand des psychiatrischen Maßregelvollzugs (§ 63 StGB)

Psychiatric forensic commitment is at the interface between psychiatry and criminal justice. Both fields are subject to societal and political influences, which are not to be underestimated and have undergone many changes since the introduction of the catalogue of penal measures in 1933. This article provides a summarizing overview of the development of psychiatric penal measures in the 8 decades since its inception. The various developmental phases are chonologically presented and analyzed, in some cases with reference to the international situation. The main transition is the change from custodial detention up to modern treatment enforcement, even if many different factors influence the certainly to be strived for further development. Finally, the complex topics of “forensic psychiatry and the public” as well as the influence of the media on this aspect are briefly discussed.     

Effect of Analogy Instructions with an Internal Focus on Learning a Complex Motor Skill

This study examined the effects of an analogy in learning breaststroke swimming. Two groups of participants had 20 lessons on how to increase their stroke length. The participants in the experimental condition received an analogy with an internal focus of attention. Inter-limb coordination showed qualitative changes in this group: a greater increase in swimming efficiency (i.e., a coordination closer to anti-phase [?50° before learning and ?125° after] and a 10% decrease in the time spent in-phase). The findings showed that an internal focus of attention induced by analogy could be beneficial in improving the quality of inter-limb swimming coordination.     

Inter-individual variability in the upper-lower limb breaststroke coordination

The aim of the present study was to examine inter-individual variability in upper-lower limb breaststroke coordination. First, inter-individual variability was compared between recreational and comparative swimmers. Second, as recreational swimmers revealed more variable inter-limb coordination than competitive swimmers, inter-individual variability was assessed among recreational swimmers to identify coordination profiles. The elbow-knee continuous relative phase (CRP) was used to analyze upper-lower limbs coupling during a breaststroke cycle. Twenty-four recreational and twenty-four competitive swimmers swam 25 m at 80% of their maximal speed. Underwater and aerial side views were mixed and genlocked. Angular position, velocity and CRP were calculated for the knee and elbow joints by digitizing body markers from the side view. The kinematics of three cycles were filtered, averaged and normalized in terms of percentage of total cycle duration. The topography of the mean CRP curve of the recreational swimmers resembled a ‘W-shape’, whereas an ‘inverse U-shape’ was seen in the competitive swimmers. However, higher inter-individual variability was observed among the recreational swimmers than among the competitive swimmers (38.1° vs. 19.4°; p < .05), suggesting that several profiles of inter-limb coordination may exist in recreational swimmers. Coordination profiling showed that three clusters could classify the recreational swimmers.     

Intrinsic Motivation and Flow in Skateboarding: An Ethnographic Study

Intrinsic motivation was examined in a spontaneous and natural context by observing and interviewing skateboarders as they engaged in their sport. At the same time, the flow phenomenon and its relationship to intrinsic motivation was explored. Data were collected from twenty skateboarders. Results indicated being intrinsically motivated can be a rich, subjective experience characterized by a sense of freedom, euphoria and efficacy, challenge and satisfaction. Likewise, flow is a rich, subjective experience characterized by peak performance, heightened concentration, positive affect, and transcendence.     

Differences in spatial-temporal parameters and arm-leg coordination in butterfly stroke as a function of race pace, skill and gender

Spatial-temporal parameters (velocity, stroke rate, stroke length) and arm-leg coordination in the butterfly stroke were studied as a function of race pace, skill (due to technical level, age, and experience) and gender. Forty swimmers (ten elite men, ten elite women, ten less-skilled men, and ten less-skilled women) performed the butterfly stroke at four velocities corresponding to the appropriate paces for the 400-m, 200-m, 100-m, and 50-m, respectively. Arm and leg stroke phases were identified by video analysis and used to calculate four time gaps (T1: the time difference between the start of the arms' catch phase and the start of the legs' downward phase of the first leg kick; T2: the time difference between the start of the arms' pull phase and the start of the legs' upward phase of the first leg kick; T3: the time difference between the start of the arms' push phase and the start of the legs' downward phase of the second leg kick; and T4: the time difference between the start of the arms' recovery and the start of the legs' upward phase of the second leg kick) and the total time gap (TTG), i.e., the sum of the four discrete time gaps. These values described the changing coupling of arm to leg actions over an entire stroke cycle. A significant race pace effect indicated that the synchronization between the key motor points of the arms and legs, which determine the starts and ends of the arm and leg stroke phases, increased with pace for all participants. A significant skill effect indicated that the elite swimmers had greater velocity, stroke length, and stroke rate and stronger synchronization of the arm and leg stroke phases than the less-skilled swimmers, due to smaller T2 and T3 and greater T1. A significant gender effect revealed greater velocity and stroke length for the men, and smaller T1 for the less-skilled women. These time gap differences between skill levels were related to the capacity of elite swimmers to assume a more streamlined position of trunk, head and upper limbs during leg actions, adopt a shorter glide and higher stroke rate to overcome great forward resistance, and generate higher forces and use better technique during the arm pull. Thus, coaches are advised to begin monitoring arm-leg coordination earlier in swimmers' careers to ensure that they attain their highest possible skill levels.