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Inside the Belly of a Beast: Individualizing Nutrition for Young, Professional Male Rugby League Players: A Review.
Kelly, VG, Oliver, LS, Bowtell, J, Jenkins, DG
International journal of sport nutrition and exercise metabolism. 2021;(1):73-89
Abstract
Professional rugby league (RL) football is a contact sport involving repeated collisions and high-intensity efforts; both training and competition involve high energy expenditure. The present review summarizes and critiques the available literature relating the physiological demands of RL to nutritional requirements and considers potential ergogenic supplements that could improve players' physical capacity, health, and recovery during the preparatory and competition phases of a season. Although there may not be enough data to provide RL-specific recommendations, the available data suggest that players may require approximately 6-8 g·kg-1·day-1 carbohydrate, 1.6-2.6 g·kg-1·day-1 protein, and 0.7-2.2 g·kg-1·day-1 fat, provided that the latter also falls within 20-35% of total energy intake. Competition nutrition should maximize glycogen availability by consuming 1-4 g/kg carbohydrate (∼80-320 g) plus 0.25 g/kg (∼20-30 g) protein, 1-4 hr preexercise for 80-120 kg players. Carbohydrate intakes of approximately 80-180 g (1.0-1.5 g/kg) plus 20-67 g protein (0.25-0.55 g/kg) 0-2 hr postexercise will optimize glycogen resynthesis and muscle protein synthesis. Supplements that potentially improve performance, recovery, and adaptation include low to moderate dosages of caffeine (3-6 mg/kg) and ∼300 mg polyphenols consumed ∼1 hr preexercise, creatine monohydrate "loading" (0.3 g·kg-1·day-1) and/or maintenance (3-5 g/day), and beta-alanine (65-80 mg·kg-1·day-1). Future research should quantify energy expenditures in young, professional male RL players before constructing recommendations.
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Anthropometric and Physiological Characteristics of Elite Male Rugby Athletes.
Brazier, J, Antrobus, M, Stebbings, GK, Day, SH, Callus, P, Erskine, RM, Bennett, MA, Kilduff, LP, Williams, AG
Journal of strength and conditioning research. 2020;(6):1790-1801
Abstract
Brazier, J, Antrobus, M, Stebbings, GK, Day, SH, Callus, P, Erskine, RM, Bennett, MA, Kilduff, LP, and Williams, AG. Anthropometric and physiological characteristics of elite male rugby athletes. J Strength Cond Res 34(6): 1790-1801, 2020-This is the first article to review the anthropometric and physiological characteristics required for elite rugby performance within both rugby union (RU) and rugby league (RL). Anthropometric characteristics such as height and body mass, and physiological characteristics such as speed and muscular strength, have previously been advocated as key discriminators of playing level within rugby. This review aimed to identify the key anthropometric and physiological properties required for elite performance in rugby, distinguishing between RU and RL, forwards and backs and competitive levels. There are differences between competitive standards such that, at the elite level, athletes are heaviest (RU forwards ∼111 kg, backs ∼93 kg; RL forwards ∼103 kg, backs ∼90 kg) with lowest % body fat (RU forwards ∼15%, backs ∼12%; RL forwards ∼14%, backs ∼11%), they have most fat-free mass and are strongest (back squat: RU forwards ∼176 kg, backs ∼157 kg; RL forwards ∼188 kg, backs ∼168 kg; bench press: RU forwards ∼131 kg, backs ∼118 kg; RL forwards ∼122 kg, backs ∼113 kg) and fastest (10 m: RU forwards ∼1.87 seconds, backs ∼1.77 seconds; 10 m: RL forwards ∼1.9 seconds, backs ∼1.83 seconds). We also have unpublished data that indicate contemporary RU athletes have less body fat and are stronger and faster than the published data suggest. Regardless, well-developed speed, agility, lower-body power, and strength characteristics are vital for elite performance, probably reflect both environmental (training, diet, etc.) and genetic factors, distinguish between competitive levels, and are therefore important determinants of elite status in rugby.
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3.
Evidence-based post-exercise recovery strategies in rugby: a narrative review.
Calleja-González, J, Mielgo-Ayuso, J, Ostojic, SM, Jones, MT, Marques-Jiménez, D, Caparros, T, Terrados, N
The Physician and sportsmedicine. 2019;(2):137-147
Abstract
In the sport of rugby, athletes need a multitude of sport-specific skills along with endurance, power, and speed to optimize performance. Further, it is not unusual for athletes to play several competitive matches with insufficient recovery time. Rugby requires repeated bouts of high-intensity actions intermixed with brief periods of low-to-moderate active recovery or passive rest. Specifically, a match is characterized by repeated explosive activities, such as jumps, shuffles, and rapid changes of direction. To facilitate adequate recovery, it is necessary to understand the type of fatigue induced and, if possible, its underlying mechanisms. Common approaches to recovery may include nutritional strategies as well as active (active recovery) and passive recovery (water immersions, stretching, and massage) methods. However, limited research exists to support the effectiveness of each strategy as it related to recovery from the sport of rugby. Therefore, the main aim of the current brief review is to present the relevant literature that pertains to recovery strategies in rugby.
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Effects of recreational football on women's fitness and health: adaptations and mechanisms.
Krustrup, P, Helge, EW, Hansen, PR, Aagaard, P, Hagman, M, Randers, MB, de Sousa, M, Mohr, M
European journal of applied physiology. 2018;(1):11-32
Abstract
The review describes the fitness and health effects of recreational football in women aged 18-65 years. The review documents that 2 × 1 h of recreational football training for 12-16 weeks causes marked improvements in maximal oxygen uptake (5-15%) and myocardial function in women. Moreover, mean arterial blood pressure was shown to decrease by 2-5 mmHg in normotensive women and 6-8 mmHg in hypertensive women. This review also show that short-term (< 4 months) and medium-term (4-16 months) recreational football training has major beneficial impact on metabolic health profile in women, with fat losses of 1-3 kg and improvements in blood lipid profile. Lastly, 2 × 1 h per week of recreational football training for women elevates lower extremity bone mineralisation by 1-5% and whole-body bone mineralization by 1-2% within 4-12-month interventions. These training adaptations are related to the high heart rates, high number of fast runs, and multiple changes of direction and speed occurring during recreational football training for untrained women. In conclusion, regular small-sided football training for women is an intense and versatile type of training that combines elements of high-intensity interval training (HIIT), endurance training and strength training, thereby providing optimal stimuli for cardiovascular, metabolic and musculoskeletal fitness. Recreational football, therefore, seems to be an effective tool for prevention and treatment of lifestyle diseases in young and middle-aged women, including hypertension, type 2 diabetes and osteopenia. Future research should elucidate effects of football training for elderly women, and as treatment and rehabilitation of breast cancer patients and other women patient groups.
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5.
Creatine kinase, neuromuscular fatigue, and the contact codes of football: A systematic review and meta-analysis of pre- and post-match differences.
Hagstrom, AD, Shorter, KA
European journal of sport science. 2018;(9):1234-1244
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Abstract
Physiological or performance tests are routinely utilised to assess athletes' recovery. At present, the ideal tool to assess recovery remains unknown. Therefore, the aim of this systematic review was to examine the change in creatine kinase (CK) and neuromuscular function as measured via a countermovement jump (CMJ) following a match in the contact codes of football. A comprehensive search of databases was undertaken with RevMan (V 5.3) used for statistical analysis. Our results demonstrated that CK pre- versus post-match (standardised mean difference (SMD) = 0.90, 95% CI = 0.50 to 1.31, p < .0001), CK pre- versus 24 h post-match (SMD = 1.50, 95% CI = 1.12 to 1.88, p < .00001), and CK pre- versus 48 h post-match all increased significantly (SMD = 0.90, 95% CI = 0.50 to 1.31, p < .0001), while CMJ peak power (PP) pre- versus post-match (SMD = -0.59, 95% CI = -1.12 to -0.06, p = .03), and pre- versus 24 h post-match (SMD = -0.80, 95% CI = -1.31 to -0.28, p = .002) decreased significantly. There was a significant relationship between the change in CK and the change in CMJ PP from immediately pre to immediately post (r = -0.924, p = .025), and between CMJ immediately following a match and 24 h CK change (r = -0.983, p = .017). In conclusion, CK levels increase and performance in the CMJ decreases following a match of a contact code of football. The identification of this relationship may allow coaching staff to implement a standalone measure of recovery.
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6.
Fatigue and Recovery in Rugby: A Review.
Tavares, F, Smith, TB, Driller, M
Sports medicine (Auckland, N.Z.). 2017;(8):1515-1530
Abstract
The physical demands and combative nature of rugby lead to notable levels of muscle damage. In professional rugby, athletes only have a limited timeframe to recover following training sessions and competition. Through the implementation of recovery strategies, sport scientists, practitioners and coaches have sought to reduce the effect of fatigue and allow athletes to recover faster. Although some studies demonstrate that recovery strategies are extensively used by rugby athletes, the research remains equivocal concerning the efficacy of recovery strategies in rugby. Moreover, given the role of inflammation arising from muscle damage in the mediation of protein synthesis mechanisms, some considerations have been raised on the long-term effect of using certain recovery modalities that diminish inflammation. While some studies aimed to understand the effects of recovery modalities during the acute recovery phase (<48 h post-match), others investigated the effect of recovery modalities during a more prolonged timeframe (i.e. during a training week). Regarding the acute effectiveness of different recovery modalities, cold water immersion and contrast baths seem to provide a beneficial effect on creatine kinase clearance, neuromuscular performance and delayed onset of muscle soreness. There is support in the literature concerning the effect of compression garments on enhancing recovery from delayed onset of muscle soreness; however, conflicting findings were observed for the restoration of neuromuscular function with the use of this strategy. Using a short-duration active recovery protocol seems to yield little benefit to recovery from rugby training or competition. Given that cold modalities may potentially affect muscle size adaptations from training, their inclusion should be treated with caution and perhaps restricted to certain periods where athlete readiness is more important than increases in muscle size.
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Thermoregulation, Fluid Balance, and Sweat Losses in American Football Players.
Davis, JK, Baker, LB, Barnes, K, Ungaro, C, Stofan, J
Sports medicine (Auckland, N.Z.). 2016;(10):1391-405
Abstract
Numerous studies have reported on the thermoregulation and hydration challenges athletes face in team and individual sports during exercise in the heat. Comparatively less research, however, has been conducted on the American Football player. Therefore, the purpose of this article is to review data collected in laboratory and field studies and discuss the thermoregulation, fluid balance, and sweat losses of American Football players. American Football presents a unique challenge to thermoregulation compared with other sports because of the encapsulating nature of the required protective equipment, large body size of players, and preseason practice occurring during the hottest time of year. Epidemiological studies report disproportionately higher rates of exertional heat illness and heat stroke in American Football compared with other sports. Specifically, larger players (e.g., linemen) are at increased risk for heat ailments compared with smaller players (e.g., backs) because of greater body mass index, increased body fat, lower surface area to body mass ratio, lower aerobic capacity, and the stationary nature of the position, which can reduce heat dissipation. A consistent finding across studies is that larger players exhibit higher sweating rates than smaller players. Mean sweating rates from 1.0 to 2.9 L/h have been reported for college and professional American Football players, with several studies reporting 3.0 L/h or more in some larger players. Sweat sodium concentration of American Football players does not seem to differ from that of athletes in other sports; however, given the high volume of sweat loss, the potential for sodium loss is higher in American Football than in other sports. Despite high sweating rates with American Football players, the observed disturbances in fluid balance have generally been mild (mean body mass loss ≤2 %). The majority of field-based studies have been conducted in the northeastern part of the United States, with limited studies in different geographical regions (i.e., southeast) of the United States. Further, there have been a limited number of studies examining body core temperature of American Football players during preseason practice, especially at the high school level. Future field-based research in American Football with various levels of competition in hotter geographical regions of the United States is warranted.
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Review of cardiometabolic risk factors among current professional football and professional baseball players.
Helzberg, JH, Camilo, J, Waeckerle, JF, O'Keefe, JH
The Physician and sportsmedicine. 2010;(3):77-83
Abstract
Data on the development of cardiovascular disease in professional football players are conflicting. Studies have documented a higher prevalence of obesity, lower high-density lipoprotein cholesterol levels, increased left ventricular and left atrial size, and higher prevalence of metabolic syndrome in former professional football linemen compared with nonlinemen. It has been suggested that former National Football League players are at risk for early cardiovascular disease and premature death. A print media report in 2006 indicated an increased prevalence of cardiovascular disease and early mortality in professional football players compared with professional baseball players. However, there has been little scientific evaluation of cardiovascular risk factors in professional baseball players. Our data suggest that there is increased cardiovascular disease risk in football players, but this is limited to heavier linemen. In preliminary studies, baseball players do not appear to demonstrate the same increased risk. However, caution should be used in the interpretation of increased cardiovascular disease risk, as it does not necessarily translate into early increased mortality.
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9.
Muscle fatigue during football match-play.
Reilly, T, Drust, B, Clarke, N
Sports medicine (Auckland, N.Z.). 2008;(5):357-67
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Abstract
One of the consequences of sustaining exercise for 90 minutes of football match-play is that the capability of muscle to generate force declines. This impairment is reflected in the decline of work-rate towards the late part of the game. Causes of this phenomenon, which is known as fatigue, and some of its consequences are considered in this article. The stores of muscle glycogen may be considerably reduced by the end of the game, especially if there has not been a tapering of the training load. Thermoregulatory strain may also be encountered, resulting in a fall in physical performance, or there may be a reduced central drive from the nervous system. The decline in muscle strength may increase the predisposition to injury in the lower limbs. Central fatigue may also occur with implications for muscle performance. Strategies to offset fatigue include astute use of substitutions, appropriate nutritional preparation and balancing pre-cooling and warm-up procedures. There is also a role for endurance training and for a pacing strategy that optimizes the expenditure of energy during match-play.
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Sweat rate and fluid turnover in American football players compared with runners in a hot and humid environment.
Godek, SF, Bartolozzi, AR, Godek, JJ
British journal of sports medicine. 2005;(4):205-11; discussion 205-11
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Abstract
OBJECTIVES To determine sweat rate (SwR) and fluid requirements for American footballers practicing in a hot, humid environment compared with cross country runners in the same conditions. METHODS Fifteen subjects, 10 footballers and five runners, participated. On the 4th and 8th day of preseason two a day practices, SwR during exercise was determined in both morning and afternoon practices/runs from the change in body mass adjusted for fluids consumed and urine produced. Unpaired t tests were used to determine differences between groups. RESULTS Overall SwR measured in litres/h was higher in the footballers than the cross country runners (2.14 (0.53) v 1.77 (0.4); p<0.01). Total sweat loss in both morning (4.83 (1.2) v 1.56 (0.39) litres) and afternoon (4.8 (1.2) v 1.97 (0.28) litres) practices/runs, and daily sweat losses (9.4 (2.2) v 3.53 (0.54) litres) were higher in the footballers (p<0.0001). The footballers consumed larger volumes of fluid during both morning and afternoon practices/runs (23.9 (8.9) v 5.5 (3.1) ml/min and 23.5 (7.3) v 13.6 (5.6) ml/min; p<0.01). For complete hydration, the necessary daily fluid consumption calculated as 130% of daily sweat loss in the footballers was 12.2 (2.9) litres compared with 4.6 (0.7) litres in the runners (p<0.0001). Calculated 24 hour fluid requirements in the footballers ranged from 8.8 to 19 litres. CONCLUSIONS The American footballers had a high SwR with large total daily sweat losses. Consuming large volumes of hypotonic fluid may promote sodium dilution. Recommendations for fluid and electrolyte replacement must be carefully considered and monitored in footballers to promote safe hydration and avoid hyponatraemia.