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- Derakhti, Mikael, et al.
(författare)
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Four Weeks of Power Optimized Sprint Training Improves Sprint Performance in Adolescent Soccer Players.
- 2022
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Ingår i: International Journal of Sports Physiology and Performance. - : Human Kinetics. - 1555-0265 .- 1555-0273. ; 17:9, s. 1343-1351
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: This study compared the effects of heavy resisted sprint training (RST) versus unresisted sprint training (UST) on sprint performance among adolescent soccer players.METHODS: Twenty-four male soccer players (age: 15.7 [0.5] y; body height: 175.7 [9.4] cm; body mass: 62.5 [9.2] kg) were randomly assigned to the RST group (n = 8), the UST group (n = 10), or the control group (n = 6). The UST group performed 8 × 20 m unresisted sprints twice weekly for 4 weeks, whereas the RST group performed 5 × 20-m heavy resisted sprints with a resistance set to maximize the horizontal power output. The control group performed only ordinary soccer training and match play. Magnitude-based decision and linear regression were used to analyze the data.RESULTS: The RST group improved sprint performances with moderate to large effect sizes (0.76-1.41) across all distances, both within and between groups (>92% beneficial effect likelihood). Conversely, there were no clear improvements in the UST and control groups. The RST evoked the largest improvements over short distances (6%-8%) and was strongly associated with increased maximum horizontal force capacities (r = .9). Players with a preintervention deficit in force capacity appeared to benefit the most from RST.CONCLUSIONS: Four weeks of heavy RST led to superior improvements in short-sprint performance compared with UST among adolescent soccer players. Heavy RST, using a load individually selected to maximize horizontal power, is therefore highly recommended as a method to improve sprint acceleration in youth athletes.
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| 2. |
- Derakhti, Mikael
(författare)
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Physical activity through enriched environment in preschool : movement, play and exploration opportunities
- 2023
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- BACKGROUND:This abstract provides a brief blueprint for a doctoral thesis that is connected to the national doctoral program Sustainable movement education (SMOVE) and research project MoveEarly.INTRODUCTION:There are overwhelming evidence for the numerous positive health benefits of physical activity (PA).1,2,3,4,5 Meanwhile, it is well known that PA-levels are insufficient in European and Swedish children alike.6,7,8 Insufficient PA-levels is a substantial societal challenge since being of concern to the immediate and future development, health and well-being of children9,10 as well as being of great economic burden to society11,12. Several policymakers, such as the World Health Organization (WHO),13 the Swedish public health agency and Swedish government14,15 highlights the importance of PA for enhancing health. Further, the Swedish school law16 and curriculum17, emphasizes a health promoting school system where preschools and schools are assigned to e.g., provide children with opportunities for daily movement as well as conditions for developing movement capabilities, enjoyment of movement and an interest to be physically active. The early childhood years, often defined as 0-5 years, is regarded as a central period for PA-promotion since being a period that is fundamental for the development of PA-behaviors, overall well-being and health18,19,20,21,22 as well being a period where young children can develop PA-behaviors that might track into adulthood23,24,25. For many Nordic children, much of their early childhood is spent in preschool, and in Sweden and Norway attendance is high, reaching >94% of 3-5 year-olds26,27 hence, it is important to investigate how to create an ECE-environment that produces enriched opportunities for movement, play, exploration and thus adequate PA. Already in 1996, Siedentop28 argued that effective PA-promotion must include a relationship between school, community, and family and that the school setting is the central point of this relationship, based on the discussion above, one could argue that today, the same goes for the preschool setting. Against this background, combined with the fact that the Swedish curriculum assigns preschools to work health promotive, the Nordic ECE is a setting well suited for PA-promotion, since it is a context encompassing most Nordic children at an age critical for their overall development and health. METHODS:The overall aim for this doctoral thesis is to, 1) develop an environment rating scale (ERS) that aligns with the theories of Ecological dynamics (ED), Enriched environment (EE) as well as the constructs of movement, play and exploration in ECE and, 2) evaluate this ERS against outcome effects such as PA, physical fitness, sleep and cognitive tasks from a large-scale intervention in ECE. To achieve this, four papers will be produced.I) a literature review on the topic of ERS in general, and on ERS in ECE specificallyII) method development of a new ERS that aligns with EE, ED, movement, play and explorationIII & IV) cross-sectional association studies investigating the associations of the newly developed ERS and outcome effects (e.g., PA and cognitive tasks) of pedagogical interventions in ECE, and RESULTS:Tentatively, the result of this dissertation is expected to provide, an ERS-tool that is able to capture how ECE environments affords, and create opportunities for movement, play and exploration in preschool children and consequently increases PA in this group. a practical ERS-tool that practitioners within ECE can use to evaluate their own environment and how it relates to creating opportunities for children’s PA via movement, play and exploration.an overview of existing ERS-tools and their characteristics, e.g., validity, reliability, context, advantages and limitations. associations between the developed ERS-tool and outcome measures on child level such as total amount of PA, physical fitness, cognitive tasks and sleep. indications of effectiveness of the ERS-tool to promote PA and child development in ECE.guidance for future research connected to PA-promotion, and child development in ECE. CONCLUSION:With individual, and public health advancements in mind, there is ample reason to enhance our understanding in the field. It is my hope that this dissertation will contribute to an ECE that advances children’s enjoyment of, and relation to, movement, learning and PA, both in an immediate and life-long perspective.
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| 3. |
- Derakhti, Mikael
(författare)
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Physical literacy and physical activity in swedish preschool children – a cross-sectional study
- 2023
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Ingår i: ECSS Paris – the 28th Annual Congress of the European College of Sport Science, 4-7 July 2023..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- INTRODUCTION:There are substantial evidence for the numerous positive health benefits of physical activity (PA) [1]. At the same time, PA-levels in European and Swedish children are insufficient [2]. Inadequate PA-levels, and associated noncommunicable diseases, are regarded as one of the most significant public health challenges confronting us. Hence, it is important to understand how we can promote ways for children to reach adequate PA-levels. Physical Literacy (PL), a theory with potential benefits for PA-behaviors and health, has garnered increasing attention over the last few years. Encompassing physical, affective, and cognitive dimensions PL is often described as an individual’s capacity, confidence, and motivation to partake- and engage in PA [3]. The early childhood years are suggested for PL promotion since this period is regarded as crucial for PA-behaviors, future health, and the opportunity to reach most children via school settings. However, the assessment and status of PL in young children, specifically in Sweden, is at best scarce. Consequently, research is required to assess PL and its connection to PA-levels in young Swedish children.METHODS:The data for this study will be derived from hip-worn accelerometers (GT3X+, Actigraph) worn for 7 days to assess PA-levels, as well as a modified version of the Canadian Preschool Physical Literacy Assessment to assess PL. The study will include 412 preschool children, aged 3-6, from 20 preschools. The data will be analyzed and presented via descriptive statistics, and multi-level linear regression models will be used to determine associations between total- and intensity stratified PA-levels and PL.RESULTS:Tentatively, the results of this study are expected to provide: 1) a picture of PL and PA in Swedish preschool children and the connection therein; 2) much-needed data for the fields of PL and early childhood research; 3) Indications on effectiveness of PL for promoting PA; and 4) guidance for future research in PL.CONCLUSION:With individual, and public health advancements in mind, there is ample reason to enhance our understanding of the relationship between PL and PA-levels of Swedish preschool children, as well as, adding data to the PL-field. The present study has the potential to contribute to these objectives.References:1. Warburton, D. E., & Bredin, S. S. (2017). Health benefits of physical activity: a systematic review of current systematic reviews. Current opinion in cardiology, 32(5), 541-556.2. Steene-Johannessen J, Hansen BH, Dalene KE, Kolle E, Northstone K, Møller NC, et al. Variations in accelerometry measured physical activity and sedentary time across Europe – harmonized analyses of 47,497 children and adolescents. Int J Behav Nutr Phys Act. 2020;17(1):38.3. Edwards, L. C., Bryant, A. S., Keegan, R. J., Morgan, K., & Jones, A. M. (2017). Definitions, foundations and associations of physical literacy: a systematic review. Sports medicine, 47(1), 113-126.
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| 4. |
- Psilander, Niklas, et al.
(författare)
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The cross-education effect in men and woman after unilateral strength training and detraining
- 2016
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- IntroductionIt is well known that muscle strength increases in both the untrained and trained limb after a period of unilateral strength training. However, it is not known how this so called cross-education effect (CE-effect) is affected by a long period of detraining, and if there are any sex differences. Also, there are conflicting results regarding the effect of unilateral training on muscle mass in the untrained limb.AimThe primary objective was to study the CE-effect in men and women after a period of unilateral strength training and detraining. The secondary objective was to study if training one limb would affect the muscle mass of the homologous opposite limb.Method Sixteen untrained individuals, 9 females and 7 males, completed the study. The training intervention was 10 weeks (34 sessions) of unilateral strength training (leg press (LP) and leg extension (LE) exercise). 1RM and muscle thickness (vastus lateralis) were measured pre-, post- and 20 weeks post-training.Results Strength (1RM) in the trained leg increased for both men and woman (LP: ~60%, LE ~20%, p<0.01), with no sex differences. However, only the men had a strength increase in the untrained leg (LP: 26%, LE: 10%, p<0.05) and the non-significant increase observed for the woman (LP: 10%, LE: 3%) was significantly smaller than the increase in the men (p<0.05). Muscle thickness increased similarly for both men and women (trained leg: ~14%, p<0.01; untrained leg: ~4%, p<0.05). The detraining period did not affect strength, but muscle thickness was reduced close to pre-training values in both men and women.Conclusion The results of the present study show that the CE-effect is larger in men than women, and that it is long lasting (at least 20 weeks). Further, strength training of one leg can increase the muscle mass of the homologous opposite leg.
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