A comparison of the reverse and power punches in oriental martial arts

In this study, we compared mechanical factors in the reverse and three-inch power punches. Twelve expert male martial artists stood on a force plate, and executed reverse and power punches against a padded target fixed to a wall-mounted force plate. The force plates measured horizontal forces, and subsequently impulses and body centre of mass velocity changes. The motions of four markers attached to the arm were also collected, and were used to compute the horizontal velocities of the knuckle and of the arm centre of mass. The power punch produced smaller velocities immediately before impact than the reverse punch for the whole-body centre of mass (0.14 vs. 0.31 m x s(-1)), for the arm centre of mass (2.86 vs. 4.68 m x s(-1)), and for the knuckle (4.09 vs. 6.43 m x s(-1)). The peak force exerted by the fist was much smaller in the power punch than in the reverse punch (790 vs. 1450 N). However, the linear impulse exerted by the fist during the first 0.20 s of contact was slightly larger in the power punch than in the reverse punch (43.2 vs. 37.7 N x s). The results indicate that the power punch is less potent than the reverse punch, but slightly more effective for throwing the opponent off balance.     

Can Interactive Web-based CAD Tools Improve the Learning of Engineering Drawing? A Case Study

Many current Web-based learning environments facilitate the theoretical teaching of a subject but this may not be sufficient for those disciplines that require a significant use of graphic mechanisms to resolve problems. This research study looks at the use of an environment that can help students learn engineering drawing with Web-based CAD tools, including a self-correction component. A comparative study of 121 students was carried out. The students were divided into two experimental groups using Web-based interactive CAD tools and into two control groups using traditional learning tools. A statistical analysis of all the samples was carried out in order to study student behavior during the research and the effectiveness of these self-study tools in the learning process. The results showed that a greater number of students in the experimental groups passed the test and improved their test scores. Therefore, the use Web-based graphic interactive tools to learn engineering drawing can be considered a significant improvement in the teaching of this kind of academic discipline.     

Isolated Obesity Is Not Enough to Impair Cardiac Autonomic Modulation in Metabolically Healthy Men

Purpose: To evaluate whether excess body mass influences the heart rate variability (HRV) indexes at rest, and to correlate adiposity indicators and the aerobic fitness with cardiac autonomic variables in metabolically healthy young adults. Method: In all, 41 untrained males (M_age = 21.80, SD = 2.14 years), 14 normal weight (M_BMI = 22.28, SD = 1.86 kg?m^?2), 11 overweight (M_BMI = 26.95, SD = 1.43 kg?m^?2), and 16 obese (M_BMI = 33.58, SD = 3.06 kg?m^?2) metabolically healthy (normal values of blood pressure, fasting blood glucose, triglycerides, and total cholesterol), underwent evaluations of the HRV at rest and of the peak oxygen consumption (VO₂ peak) during maximal exercise on a cycle ergometer. Results: Blood pressure, heart rate, HRV indexes, casual blood glucose, oxidative stress, and antioxidant activity did not differ among the groups. The VO₂ peak (mL?kg^?1?min^?1) was lower in the obese group compared with the normal weight and overweight groups. The body mass (r = ?.40 to ?.45) and abdominal circumference (r = ?.39 to ?.52) were slightly to moderately correlated with SD1, SD2, RMSSD, SDNN, pNN50, LF, and HF indexes and total power. The VO₂ peak (mL?kg^?1?min^?1) was slightly to moderately correlated (r = .48 to .51) with SD2, SDNN, and LF indexes in the individuals with excess body mass. Conclusion: Cardiac autonomic modulation at rest was preserved in metabolically healthy obese young men. However, the indicators of adiposity, as well as the aerobic fitness were correlated with cardiac autonomic modulation in the individuals with excess body mass.     

Effects of Different Models of Water-Based Resistance Training on Muscular Function of Older Women

Purpose: To compare the effects of three water-based resistance trainings on neuromuscular parameters of older women. Method: Thirty-six women were randomized to groups: simple set of 30 seconds (1 × 30 s, 66.41 ± 4.71 years, n = 12), multiple sets of 10 seconds (3 × 10 s, 66.50 ± 4.74 years, n = 11), and simple set of 10 seconds (1 × 10 s, 65.23 ± 3.93 years, n = 13). Maximal isometric strength concomitantly with neuromuscular activity during extension and flexion knee was evaluated. In the same exercises, rate of force development at different time intervals was measured. Finally, functional capacity was assessed. Results: All trainings promoted similar improvements in the rate of force develpment of extension (effect size RFD 50 ms: 1 × 30 s .49, 3 × 10 s .67, 1 × 10 s .65; ES RFD 100 ms: 1 × 30 s .76, 3 × 10 s .80, 1 × 10 s .63; ES RFD 250 ms: 1 × 30 s .31, 3 × 10 s .49, 1 × 10 s .37) and flexion knee (ES RFD 50 ms: 1 × 30 s .59, 3 × 10 s .31, 1 × 10 s .48; ES RFD 100 ms: 1 × 30 s .41, 3 × 10 s .44, 1 × 10 s .42; ES RFD 250 ms: 1 × 30 s .57, 3 × 10 s .36, 1 × 10 s .43; ES RFD maximal: 1 × 30 s .63, 3 × 10 s .23, 1 × 10 s .26), however only the 3 × 10 s group improved the performance in the 8-foot up-and-go test (ES 3 × 10 s: .93, 1 × 30: .39, 1 × 10 s: .23). There was a maintenance of the isometric force and neuromuscular activity, except for the activity of the rectus femoris that showed an increase after training in all groups (ES 3 × 10 s: .04, 1 × 30: .36, 1 × 10 s: .50). Conclusion: Water-based resistance training using simple or multiple sets promotes the same gains in rapid strength, however only multiple sets induced improvement on functional capacity.     

Helping students build competences in physical education: theoretical proposals and illustrations

In the French education system, the current curriculum for students from the primary to the end of secondary school is structured around the notion of key competence. A competence can be defined as an integrated and stable network of knowledge and know-how, with normative behaviors, procedures and types of reasoning. However, without a theoretical conceptualization of building and mobilization processes, the components of a competence are considered as isolated and not interconnected. In the health and physical education (HPE) setting, too few empirical studies have analyzed how teachers would contribute to the development of student’s competence. The aim of this forward-looking article grounded on an experiential and cultural framework consists in clarifying and illustrating a conceptualization of the dynamics of development of competences among students considering the teacher activity. This theoretical framework seems to offer heuristic possibilities for the examination of teaching and learning practices which contribute to the development of the key competences, particularly when a competence is read as an experience that integrates multiple dimensions. Based on audio-video recording of PE lessons and self-confrontation interviews with the teacher and a student, the results of the present study strengthen the criticism of the definition of competence emphasizing the relevance to adopt a holistic approach corresponding to the articulation of intertwined resources (i.e. motor, methodological and social) students allocate to act in PE groups. Furthermore, the results show that the competence building depends on various roles students have the opportunity to play in PE (i.e. observer, tutor). Finally, our results underline the importance of identifying the specific characteristics of the teacher activity designed to structure the learning environment to train students to acquire new competences transferable in society.     

The impact of exercise training on the lipid peroxidation metabolomic profile and respiratory infection risk in older adults

Aging is associated with oxidative stress that may increase susceptibility to respiratory infections (RIs). We aimed to assess the impact of exercise training on the risk of RIs in older adults and on a targeted metabolomic profile of stress oxidative lipid peroxidation-related metabolites. Methods: In an 8-month clinical trial, 38 participants over 60 years of age were allocated to an exercise group (EG), in which participants underwent 90-min training sessions three times/week(n?=?20), or a control group (CG), in which participants maintained daily physical activities(n?=?18). Daily respiratory symptoms and RIs number and severity were collected. Serum by-products were assessed by comprehensive two-dimensional gas chromatography coupled to mass spectrometry with time of flight analyzer. Serum metabolomic profiling comprised 76 metabolites (alcohols, aldehydes, alkanes, and ketones). Principal components analysis and ANOVA-simultaneous component analysis were used to evaluate the metabolomic profile change. Results: The odds ratio of RIs for the EG was 2.0 CI 95% [0.2;25]. The incidence of RIs was 47% [23;70] in the EG vs. 44%[12;77] in the CG. The metabolomic profiling showed that alkanes and aldehydes classes differed between the EG and the CG before and after intervention. A calibration model showed a relation between the metabolites from four main classes (ketones, alcohols, alkanes and aldehydes) and the prediction of the number of RIs. Conclusion: Moderate exercise training, in older adults, compared with no exercise in controls, did not show a difference in the risk of RIs. A pattern of lipid peroxidation was associated with the number of RIs.     

Metabolic demand and muscle damage induced by eccentric cycling of knee extensor and flexor muscles

The aim of this study was to examine the metabolic demand and extent of muscle damage of eccentric cycling targeting knee flexor (FLEX) and knee extensor (EXT) muscles. Methods: Eight sedentary men (23.3?±?0.7?y) underwent two eccentric cycling sessions (EXT and FLEX) of 30?min each, at 60% of the maximum power output. Oxygen consumption (VO₂), heart rate (HR) and rated perceived exertion (RPE) were measured during cycling. Countermovement and squat jumps (CMJ and SJ), muscle flexibility, muscle soreness and pain pressure threshold (PPT) of knee extensor and flexor muscles were measured before, immediately after and 1–4 days after cycling. Results: FLEX showed greater VO₂ (+23%), HR (+14%) and RPE (+18%) than EXT. CMJ and SJ performance decreased similarly after cycling. Muscle soreness increased more after EXT than FLEX and PPT decreased in knee extensor muscles after EXT and decreased in knee flexor muscles after FLEX. Greater loss of muscle flexibility in knee flexor muscles after FLEX was observed. Conclusion: Eccentric cycling of knee flexor muscles is metabolically more demanding than that of knee extensors, however muscle damage induced is similar. Knee flexors experienced greater loss of muscle flexibility possibly due to increased muscle stiffness following eccentric contractions.     

Effectiveness and time-course adaptation of resistance training vs. plyometric training in prepubertal soccer players

PurposeThis study aimed to assess the effectiveness and time course for improvements in explosive actions through resistance training (RT) vs. plyometric training (PT) in prepubertal soccer players.MethodsThirty-four male subjects were assigned to: a control group (n = 11); an RT group (5 regular soccer training sessions per week, n = 12); a PT group (3 soccer training sessions and 2 RT sessions per week, n = 11). The outcome measures included tests for the assessment of muscle strength (e.g., 1 repetition maximum half-squat test), jump ability (e.g., countermovement jump, squat jump, standing long jump, and multiple 5 bounds test), linear speed (e.g., 20 m sprint test), and change of direction (e.g., Illinois change of direction test).ResultsThe RTG showed an improvement in the half-squat (Δ = 13.2%; d = 1.3, p < 0.001) and countermovement jump (Δ = 9.4%; d = 2.4, p < 0.001) at Week 4, whereas improvements in the 20-m sprint (Δ = 4.2%; d = 1.1, p < 0.01); change of direction (CoD) (Δ = 3.8%; d = 2.1, p < 0.01); multiple 5 bounds (Δ = 5.1%; d = 1.5, p < 0.05); standing long jump (Δ = 7.2%; d = 1.2, p < 0.01); squat jump (Δ = 19.6%; d = 1.5, p < 0.01); were evident at Week 8. The PTG showed improvements in CoD (Δ = 2.1%; d = 1.3, p < 0.05); standing long jump (Δ = 9.3%; d = 1.1, p < 0.01); countermovement jump (Δ = 16.1%; d = 1.2, p < 0.01); and squat jump (Δ = 16.7%; d = 1.4, p < 0.01); at Week 8 whereas improvements in the 20-m sprint (Δ = 4.1%; d = 1.3, p < 0.01); and multiple 5 bounds (Δ = 7.4%; d = 2.4, p < 0.001); were evident only after Week. The RT and PT groups showed improvements in all sprint, CoD, and jump tests (p < 0.05) and in half-squat performance, for which improvement was only shown within the RTG (p < 0.001).ConclusionRT and PT conducted in combination with regular soccer training are safe and feasible interventions for prepubertal soccer players. In addition, these interventions were shown to be effective training tools to improve explosive actions with different time courses of improvements, which manifested earlier in the RTG than in the PTG. These outcomes may help coaches and fitness trainers set out clear and concise goals of training according to the specific time course of improvement difference between RT and PT on proxies of athletic performance of prepubertal soccer players.     

Making news of value: exploiting dissonances in economic journalism

This article explores the multiple modes of valuation that pervade newsmaking in economic journalism. It does so by exploring the different ways in which journalists at Valor Econômico, the leading economic newspaper in Brazil, compete and cooperate in the production of news. Valor is a paradigmatic case for discussing valuation practices in newsmaking since its institutional promise is to produce news of value. How, if at all, do Valor journalists embrace the promise of producing news that generates value? Elaborating on Stark’s (2009. The sense of dissonance. Accounts of worth in economic life. Princeton University Press) idea of dissonance, it is contended that different orders of worth collide and cooperate within Valor newsroom. Moreover, journalists engage in a variety of valuation practices through which these orders of worth are shaped, defined, and refined, reflecting different understandings of economy and society, and different conceptions of what journalism is good for. I argue that Valor’s direction intentionally fosters a plural space of value dissonance in order to improve the quality of news reporting. I emphasise, however, that these dissonances are only productive against a larger background of consonance about what actually there is to disagree about. The article is based on a seven-month ethnography of Valor’s newsroom in São Paulo between 2013 and 2015.