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Sports, Volume 9, Issue 2 (February 2021) – 20 articles

Cover Story (view full-size image): Concussion is a complex phenotype, influenced by environmental factors and an individual’s genetic predisposition. This article reviews concussion incidence within elite rugby, addresses the biomechanics and pathophysiology of concussion and how genetic predisposition may influence incidence, severity and outcome. View this paper
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Review
Loading Recommendations for Muscle Strength, Hypertrophy, and Local Endurance: A Re-Examination of the Repetition Continuum
Sports 2021, 9(2), 32; https://doi.org/10.3390/sports9020032 - 22 Feb 2021
Cited by 33 | Viewed by 25346
Abstract
Loading recommendations for resistance training are typically prescribed along what has come to be known as the “repetition continuum”, which proposes that the number of repetitions performed at a given magnitude of load will result in specific adaptations. Specifically, the theory postulates that [...] Read more.
Loading recommendations for resistance training are typically prescribed along what has come to be known as the “repetition continuum”, which proposes that the number of repetitions performed at a given magnitude of load will result in specific adaptations. Specifically, the theory postulates that heavy load training optimizes increases maximal strength, moderate load training optimizes increases muscle hypertrophy, and low-load training optimizes increases local muscular endurance. However, despite the widespread acceptance of this theory, current research fails to support some of its underlying presumptions. Based on the emerging evidence, we propose a new paradigm whereby muscular adaptations can be obtained, and in some cases optimized, across a wide spectrum of loading zones. The nuances and implications of this paradigm are discussed herein. Full article
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Article
Choose Where You Live Carefully: Built Environment Differences in Children’s Cardiorespiratory Fitness and Cardiometabolic Risk
Sports 2021, 9(2), 31; https://doi.org/10.3390/sports9020031 - 21 Feb 2021
Viewed by 2067
Abstract
Information regarding urban-rural differences in health indicators are scarce in Brazil. This study sought to identify rural-urban differences in cardiorespiratory fitness (CRF) and cardiometabolic risk (CMR) in Brazilian children and adolescents whilst controlling for the important confounding variables including social economic status (SES). [...] Read more.
Information regarding urban-rural differences in health indicators are scarce in Brazil. This study sought to identify rural-urban differences in cardiorespiratory fitness (CRF) and cardiometabolic risk (CMR) in Brazilian children and adolescents whilst controlling for the important confounding variables including social economic status (SES). This is a cross-sectional study developed with children and adolescents (n = 2250, age 11.54 ± 2.76) selected from a city in the south of Brazil. CRF was estimated using a 6-minute run/walk test. CMR scores were calculated by summing different cardiometabolic risk indicators. CRF was analysed assuming a multiplicative model with allometric body-size components. CMR differences in residential locations was assessed using Analysis of caovariance (ANCOVA) adopting SES, Body Mass Index (BMI), waist circumference (WC), age and fitness as covariates. Results indicated a main effect of location (p < 0.001) with children living a rural environment having the highest CRF, and children living in the periphery of towns having the lowest. Analysis also revealed significant main effects of location (p < 0.001) with children living a rural environment having the lowest CMR and children living in the centre of towns having the highest. Therefore, Brazilian children living in a rural environment appear to have superior health benefits. Full article
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Article
Determining the Optimal Workrate for Cycle Ergometer Verification Phase Testing in Males with Obesity
Sports 2021, 9(2), 30; https://doi.org/10.3390/sports9020030 - 20 Feb 2021
Cited by 1 | Viewed by 1786
Abstract
The aim of the present study was to assess the validity of verification phase (VP) testing and a 3 min all-out test to determine critical power (CP) in males with obesity. Nine young adult males with a body mass index (BMI) ≥ 30 [...] Read more.
The aim of the present study was to assess the validity of verification phase (VP) testing and a 3 min all-out test to determine critical power (CP) in males with obesity. Nine young adult males with a body mass index (BMI) ≥ 30 kg·m−2 completed a cycle ergometer ramp-style VO2max test, four randomized VP tests at 80, 90, 100, and 105% of maximum wattage attained during the ramp test, and a 3 min all-out test. There was a significant main effect for VO2max across all five tests (p = 0.049). Individually, 8 of 9 participants attained a higher VO2max (L/min) during a VP test compared to the ramp test. A trend (p = 0.06) was observed for VO2max during the 90% VP test (3.61 ± 0.54 L/min) when compared to the ramp test (3.37 ± 0.39 L/min). A significantly higher VO2max (p = 0.016) was found in the VP tests that occurred below 130% of CP wattage (N = 15, VO2max = 3.76 ± 0.52 L/min) compared to those that were above (N = 21, VO2max = 3.36 ± 0.41 L/min). Our findings suggest submaximal VP tests at 90% may elicit the highest VO2max in males with obesity and there may be merit in using % of CP wattage to determine optimal VP intensity. Full article
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Article
Low-Dose Ammonium Preconditioning Enhances Endurance in Submaximal Physical Exercises
Sports 2021, 9(2), 29; https://doi.org/10.3390/sports9020029 - 16 Feb 2021
Viewed by 1881
Abstract
Preconditioning is often used in medicine to protect organs from ischemic damage and in athletes to enhance the performances. We tested whether low-dose ammonium preconditioning (AMP) could have a beneficial effect on physical exercises (PE). We used Cardiopulmonary Exercise Testing (CPET) on a [...] Read more.
Preconditioning is often used in medicine to protect organs from ischemic damage and in athletes to enhance the performances. We tested whether low-dose ammonium preconditioning (AMP) could have a beneficial effect on physical exercises (PE). We used Cardiopulmonary Exercise Testing (CPET) on a treadmill to investigate the effects of low-dose AMP on the physical exercise capacity of professional track and field athletes and tested twenty-five athletes. Because of the individual differences between athletes, we performed a preliminary treadmill test (Pre-test) and, according to the results, the athletes were randomly allocated into the AMP and control (placebo, PL) group based on the similarity of the total distance covered on a treadmill. In the AMP group, the covered distance increased (11.3 ± 3.6%, p < 0.02) compared to Pre-test. Similarly, AMP significantly increased O2 uptake volume—VO2 (4.6 ± 2.3%, p < 0.03) and pulmonary CO2 output—VCO2 (8.7 ± 2.8%, p < 0.01). Further, the basic blood parameters (pH, pO2, and lactate) shift was lower despite the greater physical exercise progress in the AMP group compared to Pre-test, whereas in the placebo group there were no differences between Pre-test and Load-test. Importantly, the AMP significantly increased red blood cell count (6.8 ± 2.0%, p < 0.01) and hemoglobin concentration (5.3 ± 1.9%, p < 0.01), which might explain the beneficial effects in physical exercise progress. For the first time, we showed that low-dose AMP had clear beneficial effects on submaximal PE. Full article
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Article
Strength and Conditioning Practices and Perspectives of Volleyball Coaches and Players
Sports 2021, 9(2), 28; https://doi.org/10.3390/sports9020028 - 13 Feb 2021
Cited by 2 | Viewed by 2906
Abstract
To the authors’ knowledge this is the first study to describe the strength and conditioning (S&C) practices and perspectives of volleyball coaches and players. In total, 30 volleyball coaches (mean age 34.47 ± 7.83 years and coaching experience 19.57 ± 8.28 years), and [...] Read more.
To the authors’ knowledge this is the first study to describe the strength and conditioning (S&C) practices and perspectives of volleyball coaches and players. In total, 30 volleyball coaches (mean age 34.47 ± 7.83 years and coaching experience 19.57 ± 8.28 years), and 30 volleyball players (mean age 22.03 ± 4.43 years and playing experience 10.43 ± 8.98 years) completed an online survey with six sections: (a) informed consent; (b) background information; (c) education, qualifications, and prescription; (d) views on S&C; (e) exercise selection and preferences; and (f) issues and improvements. Frequency analysis was used to report responses to fixed-response questions and thematic-analysis for open-ended questions. While only one participant possessed an S&C certification, S&C was deemed ‘important’ to ‘very important’ for volleyball skills, physical fitness, and injury parameters. However, due to a reported lack of expertise, there appeared to be a theoretical understanding to practice gap. Furthermore, the implementation of S&C was considerably hindered by a lack of time, facilities, and equipment. National sports associations, coaches, and players can use the information within this study to provide an understanding of the current practices and perspectives of S&C in volleyball. While also promoting future developments in volleyball related S&C research and practice. Full article
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Article
Footwear Affects Conventional and Sumo Deadlift Performance
Sports 2021, 9(2), 27; https://doi.org/10.3390/sports9020027 - 11 Feb 2021
Cited by 1 | Viewed by 2861
Abstract
Barefoot weightlifting has become a popular training modality in recent years due to anecdotal suggestions of improved performance. However, research to support these anecdotal claims is limited. Therefore, the purpose of this study was to assess the differences between the conventional deadlift (CD) [...] Read more.
Barefoot weightlifting has become a popular training modality in recent years due to anecdotal suggestions of improved performance. However, research to support these anecdotal claims is limited. Therefore, the purpose of this study was to assess the differences between the conventional deadlift (CD) and the sumo deadlift (SD) in barefoot and shod conditions. On day one, one-repetition maximums (1 RM) were assessed for thirty subjects in both the CD and SD styles. At least 72 h later, subjects returned to perform five repetitions in four different conditions (barefoot and shod for both CD and SD) at 70% 1 RM. A 2 × 2 (footwear × lifting style) MANOVA was used to assess differences between peak vertical ground reaction force (VGRF), total mechanical work (WORK), barbell vertical displacement (DISP), peak vertical velocity (PV) and lift time (TIME) during the concentric phase. The CD displayed significant increases in VGRF, DISP, WORK, and TIME over the SD. The shod condition displayed increased WORK, DISP, and TIME compared to the barefoot condition. This study suggests that lifting barefoot does not improve performance as no differences in VGRF or PV were evident. The presence of a shoe does appear to increase the DISP and WORK required to complete the lift, suggesting an increased work load is present while wearing shoes. Full article
(This article belongs to the Special Issue Optimization of Human Performance and Health)
Communication
Bidirectional Associations between Physical Activity and Sleep in Early-Elementary-Age Latino Children with Obesity
Sports 2021, 9(2), 26; https://doi.org/10.3390/sports9020026 - 11 Feb 2021
Viewed by 1776
Abstract
Low-income Latino children are at high risk for obesity and associated comorbidities. Considering the health benefits of proper sleep habits and physical activity, understanding the patterns, or the relationship between these modifiable factors may help guide intervention strategies to improve overall health in [...] Read more.
Low-income Latino children are at high risk for obesity and associated comorbidities. Considering the health benefits of proper sleep habits and physical activity, understanding the patterns, or the relationship between these modifiable factors may help guide intervention strategies to improve overall health in this population. Thus, the purpose was to investigate bidirectional associations between physical activity and sleep among Latino children who are overweight/obese. Twenty-three children (boys, 70%; overweight, 17%; obese, 83%) (age 7.9 ± 1.4 years) wore activity monitors on their wrist for 6 consecutive days (comprising 138 total observations). Hierarchical linear modeling evaluated temporal associations between physical activity (light physical activity, LPA; moderate to vigorous activity, MVPA) and sleep (duration and efficiency). Although there was no association between MVPA and sleep (p > 0.05), daytime LPA was negatively associated with sleep duration that night (estimate ± SE = −10.77 ± 5.26; p = 0.04), and nighttime sleep efficiency was positively associated with LPA the next day (estimate ± SE = 13.29 ± 6.16; p = 0.03). In conclusion, increased LPA may decrease sleep duration that night, but increasing sleep efficiency may increase LPA the following day. Although further investigation is required, these results suggest that improving sleep efficiency may increase the level of physical activity reached among Latino children who are overweight/obese. Full article
(This article belongs to the Special Issue Physical Activity for Health in Youth)
Article
Doping Attitudes, Beliefs, and Practices among Young, Amateur Croatian Athletes
Sports 2021, 9(2), 25; https://doi.org/10.3390/sports9020025 - 09 Feb 2021
Cited by 1 | Viewed by 1840
Abstract
Recent studies revealed that amateur athletes, especially young ones, have an increasing tendency of performance-enhancing drugs (PEDs) usage. The aim of this study was to explore PEDs attitudes, beliefs, and practices among young, amateur Croatian athletes. This cross-sectional study using a specially designed [...] Read more.
Recent studies revealed that amateur athletes, especially young ones, have an increasing tendency of performance-enhancing drugs (PEDs) usage. The aim of this study was to explore PEDs attitudes, beliefs, and practices among young, amateur Croatian athletes. This cross-sectional study using a specially designed questionnaire as a research tool was done during the August 2019 to January 2020 period among a convenient sample of 400 amateur athletes of median age 18 (interquartile range 15 to 21) years. The prevalence of current PEDs usage was 1.3%, while past PEDs usage prevalence was 3.3%. Current PEDs usage was more frequent among young adults (p = 0.048) and athletes playing individual sports (p = 0.001). Athletes who were engaged in sports from one to five years had more permissive attitudes toward PEDs (p < 0.001) as measured by the Performance Enhancement Attitude Scale. Female athletes had more positive beliefs about PEDs usage (p = 0.008). The study did not establish any correlation between current or past PEDs usage and attitudes toward PEDs as well as beliefs about PEDs usage. However, there was a weak positive correlation between attitudes toward PEDs and athletes’ beliefs about PEDs usage (rs = 0.465, p < 0.001). PEDs usage is present among young Croatian amateur athletes. There is a need for interventions directed toward the prevention of PEDs usage in an observed subgroup of athletes. Full article
(This article belongs to the Special Issue Doping in Sports)
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Article
Altered Drop Jump Landing Biomechanics Following Eccentric Exercise-Induced Muscle Damage
Sports 2021, 9(2), 24; https://doi.org/10.3390/sports9020024 - 05 Feb 2021
Cited by 2 | Viewed by 2253
Abstract
Limited research exists in the literature regarding the biomechanics of the jump-landing sequence in individuals that experience symptoms of muscle damage. The present study investigated the effects of knee localized muscle damage on sagittal plane landing biomechanics during drop vertical jump (DVJ). Thirteen [...] Read more.
Limited research exists in the literature regarding the biomechanics of the jump-landing sequence in individuals that experience symptoms of muscle damage. The present study investigated the effects of knee localized muscle damage on sagittal plane landing biomechanics during drop vertical jump (DVJ). Thirteen regional level athletes performed five sets of 15 maximal eccentric voluntary contractions of the knee extensors of both legs at 60°/s. Pelvic and lower body kinematics and kinetics were measured pre- and 48 h post-eccentric exercise. The examination of muscle damage indicators included isometric torque, muscle soreness, and serum creatine kinase (CK) activity. The results revealed that all indicators changed significantly following eccentric exercise (p < 0.05). Peak knee and hip joint flexion as well as peak anterior pelvic tilt significantly increased, whereas vertical ground reaction force (GRF), internal knee extension moment, and knee joint stiffness significantly decreased during landing (p < 0.05). Therefore, the participants displayed a softer landing pattern following knee-localized eccentric exercise while being in a muscle-damaged state. This observation provides new insights on how the DVJ landing kinematics and kinetics alter to compensate the impaired function of the knee extensors following exercise-induced muscle damage (EIMD) and residual muscle soreness 48 h post-exercise. Full article
Review
Chronic and Gradual-Onset Injuries and Conditions in the Sport of Surfing: A Systematic Review
Sports 2021, 9(2), 23; https://doi.org/10.3390/sports9020023 - 29 Jan 2021
Cited by 4 | Viewed by 2519
Abstract
The majority of the previous literature investigating injuries in surfing have focused on acute or traumatic injuries. This systematic review appears to be the first to investigate the literature reporting on chronic and gradual-onset injuries and conditions in surfing populations. A search strategy [...] Read more.
The majority of the previous literature investigating injuries in surfing have focused on acute or traumatic injuries. This systematic review appears to be the first to investigate the literature reporting on chronic and gradual-onset injuries and conditions in surfing populations. A search strategy was implemented on five databases in June 2020 to locate peer-reviewed epidemiological studies on musculoskeletal injuries or non-musculoskeletal conditions in surfing. A modified AXIS Critical Appraisal Tool was used to appraise all included texts. Extracted data included key information relevant to the epidemiology of the injuries and conditions. Twenty journal articles were included with the majority rated as good quality and a substantial agreement between raters (k = 0.724). Spine/back (29.3%), shoulder (22.9%), and head/face/neck (17.5%) were the most frequently reported locations of musculoskeletal injury, whilst the most common mechanism of injury was paddling (37.1%). Exostosis was the most frequently described injury or condition in surfing populations, with the most common grade of severity reported as mild obstruction. The key findings of injury type, location, severity, and mechanism can be used to develop relevant injury management and prevention programs for the surfing population, with an emphasis on chronic or gradual-onset spine/back and shoulder injuries, paddling technique, and education on the development and management of exostosis. Full article
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Article
Association of Genetic Variances in ADRB1 and PPARGC1a with Two-Kilometre Running Time-Trial Performance in Australian Football League Players: A Preliminary Study
Sports 2021, 9(2), 22; https://doi.org/10.3390/sports9020022 - 29 Jan 2021
Cited by 1 | Viewed by 1788
Abstract
Genetic variants in the angiotensin-converting enzyme (ACE) (rs4343), alpha-actinin-3 (ACTN3) (rs1815739), adrenoceptor-beta-1 (ADRB1) (rs1801253), and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A) (rs8192678) genes have previously been associated with elite athletic performance. This study assessed [...] Read more.
Genetic variants in the angiotensin-converting enzyme (ACE) (rs4343), alpha-actinin-3 (ACTN3) (rs1815739), adrenoceptor-beta-1 (ADRB1) (rs1801253), and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A) (rs8192678) genes have previously been associated with elite athletic performance. This study assessed the influence of polymorphisms in these candidate genes towards endurance test performance in 46 players from a single Australian Football League (AFL) team. Each player provided saliva buccal swab samples for DNA analysis and genotyping and were required to perform two independent two-kilometre running time-trials, six weeks apart. Linear mixed models were created to account for repeated measures over time and to determine whether player genotypes are associated with overall performance in the two-kilometre time-trial. The results showed that the ADRB1 Arg389Gly CC (p = 0.034) and PPARGC1A Gly482Ser GG (p = 0.031) genotypes were significantly associated with a faster two-kilometre time-trial. This is the first study to link genetic polymorphism to an assessment of endurance performance in Australian Football and provides justification for further exploratory or confirmatory studies. Full article
Article
A Comparison of PlayerLoadTM and Heart Rate during Backwards and Forwards Locomotion during Intermittent Exercise in Rugby League Players
Sports 2021, 9(2), 21; https://doi.org/10.3390/sports9020021 - 25 Jan 2021
Cited by 1 | Viewed by 1704
Abstract
Limited research has examined the demands of backward locomotion at various speeds using common load monitoring metrics in team sport athletes. Consequently, this study compared the external and internal loads between backward and forward locomotion during intermittent exercise in team sport athletes. Semi-professional, [...] Read more.
Limited research has examined the demands of backward locomotion at various speeds using common load monitoring metrics in team sport athletes. Consequently, this study compared the external and internal loads between backward and forward locomotion during intermittent exercise in team sport athletes. Semi-professional, male rugby league players (n = 29) completed the same exercise protocol on two occasions in backward and forward directions. On each occasion, participants performed separate 20 m trials at self-selected walking, jogging, running, and sprinting speeds and then completed a 15 min modified Loughborough intermittent shuttle test (mLIST). Common external and internal load metrics were gathered across testing. Faster speeds (p < 0.001) were attained at all speeds during forward locomotion in the 20 m trials. Non-significant differences in accumulated PlayerLoadTM were found between directions across the mLIST; however, higher relative (per min) PlayerLoadTM (p < 0.001) was apparent during backward locomotion when walking and during forward locomotion when sprinting during the mLIST. RPE and mean heart rate were higher (p < 0.001) during backward locomotion across the mLIST. These data highlight the unique loading patterns experienced during backward locomotion and suggest practitioners should consider the discernment in loading imposed between backward and forward locomotion when measuring athlete demands using common metrics. Full article
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Editorial
Acknowledgment to Reviewers of Sports in 2020
Sports 2021, 9(2), 20; https://doi.org/10.3390/sports9020020 - 24 Jan 2021
Viewed by 1482
Abstract
Peer review is the driving force of journal development, and reviewers are gatekeepers who ensure that Sports maintains its standards for the high quality of its published papers [...] Full article
Review
Genetic Factors That Could Affect Concussion Risk in Elite Rugby
Sports 2021, 9(2), 19; https://doi.org/10.3390/sports9020019 - 22 Jan 2021
Cited by 1 | Viewed by 2663
Abstract
Elite rugby league and union have some of the highest reported rates of concussion (mild traumatic brain injury) in professional sport due in part to their full-contact high-velocity collision-based nature. Currently, concussions are the most commonly reported match injury during the tackle for [...] Read more.
Elite rugby league and union have some of the highest reported rates of concussion (mild traumatic brain injury) in professional sport due in part to their full-contact high-velocity collision-based nature. Currently, concussions are the most commonly reported match injury during the tackle for both the ball carrier and the tackler (8–28 concussions per 1000 player match hours) and reports exist of reduced cognitive function and long-term health consequences that can end a playing career and produce continued ill health. Concussion is a complex phenotype, influenced by environmental factors and an individual’s genetic predisposition. This article reviews concussion incidence within elite rugby and addresses the biomechanics and pathophysiology of concussion and how genetic predisposition may influence incidence, severity and outcome. Associations have been reported between a variety of genetic variants and traumatic brain injury. However, little effort has been devoted to the study of genetic associations with concussion within elite rugby players. Due to a growing understanding of the molecular characteristics underpinning the pathophysiology of concussion, investigating genetic variation within elite rugby is a viable and worthy proposition. Therefore, we propose from this review that several genetic variants within or near candidate genes of interest, namely APOE, MAPT, IL6R, COMT, SLC6A4, 5-HTTLPR, DRD2, DRD4, ANKK1, BDNF and GRIN2A, warrant further study within elite rugby and other sports involving high-velocity collisions. Full article
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Article
Exercise Intensity during Olympic-Distance Triathlon in Well-Trained Age-Group Athletes: An Observational Study
Sports 2021, 9(2), 18; https://doi.org/10.3390/sports9020018 - 21 Jan 2021
Cited by 3 | Viewed by 2241
Abstract
The aim of this study was to examine the exercise intensity during the swimming, cycling, and running legs of nondraft legal, Olympic-distance triathlons in well-trained, age-group triathletes. Seventeen male triathletes completed incremental swimming, cycling, and running tests to exhaustion. Heart rate (HR) and [...] Read more.
The aim of this study was to examine the exercise intensity during the swimming, cycling, and running legs of nondraft legal, Olympic-distance triathlons in well-trained, age-group triathletes. Seventeen male triathletes completed incremental swimming, cycling, and running tests to exhaustion. Heart rate (HR) and workload corresponding to aerobic and anaerobic thresholds, maximal workloads, and maximal HR (HRmax) in each exercise mode were analyzed. HR and workload were monitored throughout the race. The intensity distributions in three HR zones for each discipline and five workload zones in cycling and running were quantified. The subjects were then assigned to a fast or slow group based on the total race time (range, 2 h 07 min–2 h 41 min). The mean percentages of HRmax in the swimming, cycling, and running legs were 89.8% ± 3.7%, 91.1% ± 4.4%, and 90.7% ± 5.1%, respectively, for all participants. The mean percentage of HRmax and intensity distributions during the swimming and cycling legs were similar between groups. In the running leg, the faster group spent relatively more time above HR at anaerobic threshold (AnT) and between workload at AnT and maximal workload. In conclusion, well-trained male triathletes performed at very high intensity throughout a nondraft legal, Olympic-distance triathlon race, and sustaining higher intensity during running might play a role in the success of these athletes. Full article
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Article
Nutritional Practice and Nitrogen Balance in Elite Japanese Swimmers during a Training Camp
Sports 2021, 9(2), 17; https://doi.org/10.3390/sports9020017 - 21 Jan 2021
Cited by 1 | Viewed by 1749
Abstract
The protein requirement in athletes increases as a result of exercise-induced changes in protein metabolism. In addition, the frequency, quantity, and quality (i.e., leucine content) of the protein intake modulates the protein metabolism. Thus, this study aimed to investigate whether nutritional practice (particularly, [...] Read more.
The protein requirement in athletes increases as a result of exercise-induced changes in protein metabolism. In addition, the frequency, quantity, and quality (i.e., leucine content) of the protein intake modulates the protein metabolism. Thus, this study aimed to investigate whether nutritional practice (particularly, protein and amino acid intake at each eating occasion) meets the protein needs required to achieve zero nitrogen balance in elite swimmers during a training camp. Eight elite swimmers (age 21.9 ± 2.3 years, body weight 64.2 ± 7.1 kg, sex M:2 F:6) participated in a four-day study. The nitrogen balance was calculated from the dietary nitrogen intake and urinary nitrogen excretion. The amino acid intake was divided over six eating occasions. The nitrogen balance was found to be positive (6.7 ± 3.1 g N/day, p < 0.05) with protein intake of 2.96 ± 0.74 g/kg/day. The frequency and quantity of leucine and the protein intake were met within the recommended range established by the International Society of Sports Nutrition. Thus, a protein intake of 2.96 g/kg/day with a well-designated pattern (i.e., frequency throughout the day, as well as quantity and quality) of protein and amino acid intake may satisfy the increased need for protein in an elite swimmer. Full article
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Article
Sprint Kayaking Performance Enhancement by Isometric Strength Training Inclusion: A Randomized Controlled Trial
Sports 2021, 9(2), 16; https://doi.org/10.3390/sports9020016 - 21 Jan 2021
Cited by 3 | Viewed by 2097
Abstract
Performing isometric strength training (IST) can enhance various sports performance. This study compared the effects of including IST on sprint kayaking performance as compared to traditional strength training. Twenty sprint kayaking athletes (age 22 ± 4 year, stature 1.71 ± 0.09 m, body [...] Read more.
Performing isometric strength training (IST) can enhance various sports performance. This study compared the effects of including IST on sprint kayaking performance as compared to traditional strength training. Twenty sprint kayaking athletes (age 22 ± 4 year, stature 1.71 ± 0.09 m, body mass 72.0 ± 11.4 kg) performed a 200-m kayak ergometer time trial (200mTT), isometric squat (IsoSqT), isometric bench press (IsoPress) and isometric prone bench pull (IsoPull) during the pre- and post-tests. Athletes were randomly assigned to either traditional strength training (TRAD) or IST group. Both groups performed a similar strength training program twice a week for six weeks. However, half the volume for squat, bench press and prone bench pull were replaced by IsoSqT, IsoPress and IsoPull, respectively, for the IST group. IsoSqT was performed at 90° knee angle, while IsoPress and IsoPull were performed at 90° and 120° elbow angles, respectively. Each isometric contraction was performed with maximum intensity and sustained for three seconds. A significant main time effect was observed for 200mTT (p < 0.001, ƞ2p = 0.68) and all isometric strength measures (p = 0.001–0.032, ƞ2p = 0.24–0.76) except rate of force development at 0–90 ms (RFD90) obtained from IsoSqT120 and IsoPress90. A group main effect was observed in RFD90 obtained from IsoSqT120 and IsoPull120 (p = 0.003–0.004, ƞ2p = 0.37–0.39). Time x Group interaction was observed for 200mTT (p = 0.027, ƞ2p = 0.68), peak force obtained from IsoSqT90, IsoPress90, and IsoPull120 (p = 0.004–0.006, ƞ2p = 0.36–0.38) and RFD90 obtained from IsoSqT120 and IsoPull120 (p = 0.012–0.015, ƞ2p = 0.28–0.30). Inclusion of IST resulted in greater improvement for sprint kayaking and strength performances then TRAD alone. Full article
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Review
Applications of the Critical Power Model to Dynamic Constant External Resistance Exercise: A Brief Review of the Critical Load Test
Sports 2021, 9(2), 15; https://doi.org/10.3390/sports9020015 - 21 Jan 2021
Cited by 3 | Viewed by 1813
Abstract
The study and application of the critical power (CP) concept has spanned many decades. The CP test provides estimates of two distinct parameters, CP and W′, that describe aerobic and anaerobic metabolic capacities, respectively. Various mathematical models have been used to estimate the [...] Read more.
The study and application of the critical power (CP) concept has spanned many decades. The CP test provides estimates of two distinct parameters, CP and W′, that describe aerobic and anaerobic metabolic capacities, respectively. Various mathematical models have been used to estimate the CP and W′ parameters across exercise modalities. Recently, the CP model has been applied to dynamic constant external resistance (DCER) exercises. The same hyperbolic relationship that has been established across various continuous, whole-body, dynamic movements has also been demonstrated for upper-, lower-, and whole-body DCER exercises. The asymptote of the load versus repetition relationship is defined as the critical load (CL) and the curvature constant is L′. The CL and L′ can be estimated from the same linear and non-linear mathematical models used to derive the CP. The aims of this review are to (1) provide an overview of the CP concept across continuous, dynamic exercise modalities; (2) describe the recent applications of the model to DCER exercise; (3) demonstrate how the mathematical modeling of DCER exercise can be applied to further our understanding of fatigue and individual performance capabilities; and (4) make initial recommendations regarding the methodology for estimating the parameters of the CL test. Full article
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Article
Impact of Different Exercise Modalities on the Human Gut Microbiome
Sports 2021, 9(2), 14; https://doi.org/10.3390/sports9020014 - 21 Jan 2021
Cited by 19 | Viewed by 4310
Abstract
In this study we examined changes to the human gut microbiome resulting from an eight-week intervention of either cardiorespiratory exercise (CRE) or resistance training exercise (RTE). Twenty-eight subjects (21 F; aged 18–26) were recruited for our CRE study and 28 subjects (17 F; [...] Read more.
In this study we examined changes to the human gut microbiome resulting from an eight-week intervention of either cardiorespiratory exercise (CRE) or resistance training exercise (RTE). Twenty-eight subjects (21 F; aged 18–26) were recruited for our CRE study and 28 subjects (17 F; aged 18–33) were recruited for our RTE study. Fecal samples for gut microbiome profiling were collected twice weekly during the pre-intervention phase (three weeks), intervention phase (eight weeks), and post-intervention phase (three weeks). Pre/post VO2max, three repetition maximum (3RM), and body composition measurements were conducted. Heart rate ranges for CRE were determined by subjects’ initial VO2max test. RTE weight ranges were established by subjects’ initial 3RM testing for squat, bench press, and bent-over row. Gut microbiota were profiled using 16S rRNA gene sequencing. Microbiome sequence data were analyzed with QIIME 2. CRE resulted in initial changes to the gut microbiome which were not sustained through or after the intervention period, while RTE resulted in no detectable changes to the gut microbiota. For both CRE and RTE, we observe some evidence that the baseline microbiome composition may be predictive of exercise gains. This work suggests that the human gut microbiome can change in response to a new exercise program, but the type of exercise likely impacts whether a change occurs. The changes observed in our CRE intervention resemble a disturbance to the microbiome, where an initial shift is observed followed by a return to the baseline state. More work is needed to understand how sustained changes to the microbiome occur, resulting in differences that have been reported in cross sectional studies of athletes and non-athletes. Full article
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Editorial
Periodization and Programming in Sports
Sports 2021, 9(2), 13; https://doi.org/10.3390/sports9020013 - 20 Jan 2021
Cited by 1 | Viewed by 2200
Abstract
Periodization is a generally accepted approach to manage athletic performance by the sub-division of training programs into sequential, specifically focused training periods [...] Full article
(This article belongs to the Special Issue Periodization and Programming in Sports)
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