Changes in anthropometry, upper-body strength, and nutrient intake in professional Australian football players during a season

©2016 Human Kinetics,Inc. The purpose of this study was to examine the seasonal changes in body composition, nutrition, and upper-body (UB) strength in professional Australian Football (AF) players. The prospective longitudinal study examined changes in anthropometry (body mass, fat-free soft-tissue mass [FFSTM], and fat mass) via dual-energy X-ray absorptiometry 5 times during an AF season (start preseason, midpreseason, start season, midseason, end season) in 45 professional AF players. Dietary intakes and strength (bench press and bench pull) were also assessed at these time points. Players were categorized as experienced (>4 y experience, n = 23) or inexperienced (1 y to develop the appropriate levels of FFSTM in young players and take a long-term view when developing the physical and performance abilities of inexperienced players

The preparation period in basketball: Training load and neuromuscular adaptations

© 2018 Human Kinetics, Inc. Purpose: To investigate the effect of the preparation period on neuromuscular characteristics of 12 professional (PRO) and 16 semiprofessional (SEMIPRO) basketball players and relationships between training-load indices and changes in neuromuscular physical performance. Methods: Before and after the preparation period, players underwent a countermovement jump (CMJ) test followed by a repeated change-of-direction (COD) test consisting of 4 levels with increasing intensities. The peripheral neuromuscular functions of the knee extensors (peak torque [PT]) were measured using electrical stimulations after each level (PT1, PT2, PT3, and PT4). Furthermore, PT Max (the highest value of PT) and PT Dec (PT decrement from PT Max to PT4) were calculated. Results: Trivial to small (effect size [ES] = -0.17 to 0.46) improvements were found in CMJ variables, regardless of competitive level. After the preparation period, peripheral fatigue induced by a COD test was similarly reduced in both PRO (PT Dec: from 27.8% [21.3%] to 11.4% [13.7%]; ES = -0.71; 90% confidence interval [CI], ±0.30) and SEMIPRO (PT Dec: from 26.1% [21.9%] to 10.2% [8.2%]; ES = -0.69; 90% CI, ±0.32). Moderate to large relationships were found between session rating of perceived exertion training load and changes in peak power output (PPO) measured during the CMJs (rs [90% confidence interval]: PPOabs, -.46 [±.26]; PPOrel, -.53 [±.23]) and in some PTs measured during the COD test (PT1, -.45 [±.26]; PT2, -.44 [±.26]; PT3, -.40 [±.27]; and PT Max, -.38 [±.28]). Conclusions: The preparation period induced minimal changes in the CMJ, while the ability to sustain repeated COD efforts was improved. Reaching high session rating of perceived exertion training loads might partially and negatively affect the ability to produce strength and power

Prolonged Antigen Presentation Is Required for Optimal CD8+ T Cell Responses against Malaria Liver Stage Parasites

Immunization with irradiated sporozoites is currently the most effective vaccination strategy against liver stages of malaria parasites, yet the mechanisms underpinning the success of this approach are unknown. Here we show that the complete development of protective CD8+ T cell responses requires prolonged antigen presentation. Using TCR transgenic cells specific for the malaria circumsporozoite protein, a leading vaccine candidate, we found that sporozoite antigen persists for over 8 weeks after immunization—a remarkable finding since irradiated sporozoites are incapable of replication and do not differentiate beyond early liver stages. Persisting antigen was detected in lymphoid organs and depends on the presence of CD11c+ cells. Prolonged antigen presentation enhanced the magnitude of the CD8+ T cell response in a number of ways. Firstly, reducing the time primed CD8+ T cells were exposed to antigen in vivo severely reduced the final size of the developing memory population. Secondly, fully developed memory cells expanded in previously immunized mice but not when transferred to naïve animals. Finally, persisting antigen was able to prime naïve cells, including recent thymic emigrants, to become functional effector cells capable of eliminating parasites in the liver. Together these data show that the optimal development of protective CD8+ T cell immunity against malaria liver stages is dependent upon the prolonged presentation of sporozoite-derived antigen

International Society of Sports Nutrition Position Stand: Nutritional recommendations for single-stage ultra-marathon; training and racing

Background. In this Position Statement, the International Society of Sports Nutrition (ISSN) provides an objective and critical review of the literature pertinent to nutritional considerations for training and racing in single-stage ultra-marathon. Recommendations for Training. i) Ultra-marathon runners should aim to meet the caloric demands of training by following an individualized and periodized strategy, comprising a varied, food-first approach; ii) Athletes should plan and implement their nutrition strategy with sufficient time to permit adaptations that enhance fat oxidative capacity; iii) The evidence overwhelmingly supports the inclusion of a moderate-to-high carbohydrate diet (i.e., ~60% of energy intake, 5 – 8 g⸱kg−1·d−1) to mitigate the negative effects of chronic, training-induced glycogen depletion; iv) Limiting carbohydrate intake before selected low-intensity sessions, and/or moderating daily carbohydrate intake, may enhance mitochondrial function and fat oxidative capacity. Nevertheless, this approach may compromise performance during high-intensity efforts; v) Protein intakes of ~1.6 g·kg−1·d−1 are necessary to maintain lean mass and support recovery from training, but amounts up to 2.5 g⸱kg−1·d−1 may be warranted during demanding training when calorie requirements are greater; Recommendations for Racing. vi) To attenuate caloric deficits, runners should aim to consume 150 - 400 kcal⸱h−1 (carbohydrate, 30 – 50 g⸱h−1; protein, 5 – 10 g⸱h−1) from a variety of calorie-dense foods. Consideration must be given to food palatability, individual tolerance, and the increased preference for savory foods in longer races; vii) Fluid volumes of 450 – 750 mL⸱h−1 (~150 – 250 mL every 20 min) are recommended during racing. To minimize the likelihood of hyponatraemia, electrolytes (mainly sodium) may be needed in concentrations greater than that provided by most commercial products (i.e., >575 mg·L−1 sodium). Fluid and electrolyte requirements will be elevated when running in hot and/or humid conditions; viii) Evidence supports progressive gut-training and/or low-FODMAP diets (fermentable oligosaccharide, disaccharide, monosaccharide and polyol) to alleviate symptoms of gastrointestinal distress during racing; ix) The evidence in support of ketogenic diets and/or ketone esters to improve ultra-marathon performance is lacking, with further research warranted; x) Evidence supports the strategic use of caffeine to sustain performance in the latter stages of racing, particularly when sleep deprivation may compromise athlete safety

Factors affecting fat-free soft tissue mass in Australian Rules football players

University of Technology, Sydney. Faculty of Health.NO FULL TEXT AVAILABLE. This thesis contains 3rd party copyright material. The hardcopy may be available for consultation at the UTS Library.NO FULL TEXT AVAILABLE. This thesis contains 3rd party copyright material. ----- Introduction: Professional Australian Football (AF) is a physically demanding field sport that requires prolonged, high-intensity, intermittent exercise, and is punctuated by many intense accelerations and decelerations (Gray & Jenkins, 2010; Harcourt, Marclay, & Clothier, 2014). In addition to these running demands, AF players are also required to jostle and tackle an opponent and complete very intense skill actions which contribute to the high physical demands of the game. With such high demands, there is a need for a better understanding of the factors that are related to training and match performance. To meet these demands, developing optimal body composition, fat-free soft tissue mass (FFSTM) and fat mass (FM) are considered essential for success for professional AF players. Indeed, physical performance is reliant on muscular activity and therefore it is likely that FFSTM is an important physical characteristic for success in AF. Recent research has suggested FFSTM underpins physical performance in AF (Hrysomallis & Buttifant, 2012). Excess FM however, can be considered detrimental to performance as it is metabolically inactive. Therefore it is important that optimal levels of FFSTM and FM are developed in professional AF players. Despite the perceived importance of FFSTM for AF players, very few studies have investigated the factors related to developing and maintaining optimal body composition in this group. Therefore, the overall goals of this thesis were to: 1) determine the most accurate and precise method to assess anthropometry in AF players, 2) compare the anthropometry, upper body strength and lower body power characteristics in elite junior, sub-elite senior and elite senior AF players, 3) examine the seasonal changes in body composition, dietary intakes, and upper body strength in professional AF players, 4 compare the variations in body composition of early, mid and late career professional AF players over three successive preseasons. The results of five separate studies were reported in five manuscripts. Study 1: Different methods such as skinfolds, bioelectrical impedance (BIA), and dual-energy X-ray absorptiometry (DXA) are used to estimate FFSTM and FM in AF players. However, DXA is commonly reported to be the gold standard measurement device for this purpose. Therefore, a comprehensive evaluation of the precision and accuracy of two different DXA devices for measuring FFSTM, FM and BMC was completed. Additionally, a comparison of the construct validity and reliability of skinfold and BIA measures was also undertaken. DXA showed exceptional precision and accuracy for fat-free soft tissue mass (FFSTM), bone mineral content and fat mass. Body fat percentage derived from a football-specific skinfold equation and the Σ7 skinfolds both showed poor relationships with the criterion measures estimated from DXA. Bioelectrical impedance analysis also showed both poor accuracy and precision for AF players. These results showed that DXA provides an accurate and precise measure for body composition and that the other indirect methods may not be sensitive enough in elite AF players. Study 2: Described the anthropometry, upper body strength and lower body power characteristics in elite junior (n =21), sub-elite senior (n = 22) and elite senior (n = 27) AF players. Relationships between the whole body and appendicular body composition and neuromuscular strength and power characteristics were determined. Elite senior and sub-elite senior players were significantly older and heavier than the elite junior players. Both elite playing groups had greater total FFSTM than both the sub-elite and junior elite players, however, there were only appendicular FFSTM differences between the junior elite and elite senior players. The elite senior playing groups were stronger and had greater counter movement jump performance than the lower level players. Both whole body and appendicular FFSTM were correlated with upper body strength measures. The FFSTM are different between AF players competing at different levels, which are likely due to training and partly explain the observed differences in strength and power performance. These findings highlight the importance of optimizing FFSTM in developing AF players and maintaining these levels during a professional career. Study 3: A prospective longitudinal study examined the seasonal changes in body composition, dietary intakes, and upper body strength in 23 elite experienced (>4 years contracted) and 22 elite inexperienced (contracted <4 years) AF players. FM decreased during the preseason but was maintained through the competition season for both groups. Body mass was unchanged during the season, %FFSTM was increased during the preseason and remained constant thereafter. Upper body strength increased during the preseason and was maintained during the competition season. Total energy and carbohydrate intakes were similar between the experienced and inexperienced players during the season, but there were greater fat intakes at the start of the season, increased alcohol and reduced protein intake at the end (post) of the season. The inexperienced players consumed more fat at the start of season and less total protein during the season compared to the experienced players. Changes in FFSTM were related to changes in upper strength performance. Study 4: This prospective longitudinal study examined the changes in anthropometry during the inseason and establish how they impact on performance and training variables in 34 elite Australian football players. Training characteristics, wellness scores, fatigue scores, nutrient intakes along with physical performance characteristics (bench press, bench pull,) were also taken at each of these time points. Players were categorised into groups that Gained, Maintained or Lost FFSTM during the inseason. There were no clear differences between groups in height, age or %FFSTM, number of training sessions or time (minutes) of training completed. Players that maintained FFSTM had a higher body mass (BM) and reported a higher session-RPE loads. The group that gained FFSTM had greater bench press strength and body mass loss whilst those who maintained FFSTM completed greater training loads and missed fewer games through injury. Players who maintained FFSTM played more first grade games whilst those who lost FFSTM played more second grade games. Study 5: Compared the variations in body composition, via DXA, and dietary intakes of early, mid and late career professional Australian football players over 3 successive preseasons. 22 elite Australian football players were assessed for bone mineral content, fat mass and fat-free soft tissue mass four times per season over a 3-year period. Players were classified according to their age at the beginning of the observational period as either early (25 y; N = 5) career athletes. Regional and total body composition was assessed four times, at the same time of each season: 1) start preseason (SP); 2) end preseason (EP); midseason (MS); and end-season (ES) from 22 professional AF players using pencil beam dual energy x-ray absorptiometry. Nutritional intake for each player was evaluated concomitantly using 3-day food diaries. Players were classified according to their age at the beginning of the observational period as either early (25 y; N = 5) career athletes. Early career players had lower FFSTM, BMC and BM compared to mid and late career players FFSTM, %FFSTM, BMC and BM showed small variations throughout. FM and %FM had greatest variability, particularly in the early career players. FM reduced and FFSTM increased from SP to EP, whilst FM and FFSTM decreased from EP to MS. FM increased and FFSTM decreased from MS to ES, whilst FM and FFSTM increased during the offseason

Longitudinal changes and seasonal variation in body composition in professional Australian football players

© 2017 Human Kinetics, Inc. Purpose: To compare development and variations in body composition of early-, mid-, and late-career professional Australian Football (AF) players over 3 successive seasons. Methods: Regional and total-body composition (body mass [BM], fat mass [FM], fat-free soft-tissue mass [FFSTM], and bone mineral content [BMC]) were assessed 4 times, at the same time of each season - start preseason (SP), end preseason (EP), midseason (MS), and end season (ES) - from 22 professional AF players using pencil-beam dual-energy X-ray absorptiometry. Nutritional intake for each player was evaluated concomitantly using 3-d food diaries. Players were classified according to their age at the beginning of the observational period as either early- (25 y, n = 5) career athletes. Results: Early-career players had lower FFSTM, BMC, and BM than mid- and late-career throughout. FM and %FM had greatest variability, particularly in the early-career players. FM reduced and FFSTM increased from SP to EP, while FM and FFSTM decreased from EP to MS. FM increased and FFSTM decreased from MS to ES, while FM and FFSTM increased during the off-season. Conclusions: Early-career players may benefit from greater emphasis on specific nutrition and resistance-training strategies aimed at increasing FFSTM, while all players should balance training and diet toward the end of season to minimize increases in FM

Match-to-match variation in physical activity and technical skill measures in professional Australian Football

© 2013 Sports Medicine Australia. Objectives: To determine the match-to-match variability in physical activity and technical performance measures in Australian Football, and examine the influence of playing position, time of season, and different seasons on these measures of variability. Design: Longitudinal observational study. Methods: Global positioning system, accelerometer and technical performance measures (total kicks, handballs, possessions and Champion Data rank) were collected from 33 players competing in the Australian Football League over 31 matches during 2011-2012 (N=511 observations). The global positioning system data were categorised into total distance, mean speed (mmin-1), high-speed running (>14.4kmh-1), very high-speed running (>19.9kmh-1), and sprint (>23.0kmh-1) distance while player load was collected from the accelerometer. The data were log transformed to provide coefficient of variation and the between subject standard deviation (expressed as percentages). Results: Match-to-match variability was increased for higher speed activities (high-speed running, very high-speed running, sprint distance, coefficient of variation %: 13.3-28.6%) compared to global measures (speed, total distance, player load, coefficient of variation %: 5.3-9.2%). The between-match variability was relativity stable for all measures between and within AFL seasons, with only few differences between positions. Higher speed activities (high-speed running, very high-speed running, sprint distance), but excluding mean speed, total distance and player load, were all higher in the final third phase of the season compared to the start of the season. Conclusions: While global measures of physical performance are relatively stable, higher-speed activities and technical measures exhibit a large degree of between-match variability in Australian Football. However, these measures remain relatively stable between positions, and within and between Australian Football League seasons

Match score affects activity profile and skill performance in professional Australian Football players

Objectives: To examine the influence of quarter outcome and the margin of the score differential on both the physical activity profile and skill performance of players during professional Australian Football matches. Design: Prospective, longitudinal. Methods: Physical activity profiles were assessed via microtechnology (Global Positioning System and accelerometer) from 40 professional AF players from the same team during 15 Australian Football League games. Skill performance measures (involvement and effectiveness) and player rank scores (Champion Data© Rank) were provided by a commercial statistical provider. The physical performance variables, skill involvements and individual player performance scores were expressed relative to playing time for each quarter. The influence of the quarter result (i.e. win vs. loss) and score margin (i.e. small: 19 points) on activity profile and skill involvements and skill efficiency performance of players were examined. Results: Skill involvements (total disposals/min, long kicks/min, marks/min, running bounces/min and player rank/min) were greater in quarters won (all p14.5kmh-1, HSR/min), sprints/min and peak speed were higher in losing quarters (all p<0.01). Smaller score margins were associated with increased physical activity (m/min, HSR/min, and body load/min, all p<0.05) and decreased skill efficiency (handball clangers/min and player rank/min, all p<0.05). Conclusions: Professional AF players are likely to have an increased physical activity profile and decreased skill involvement and proficiency when their team is less successful. © 2013 Sports Medicine Australia

Factors affecting match performance in professional australian football

To determine the physical activity measures and skill-performance characteristics that contribute to coaches' perception of performance and player performance rank in professional Australian Football (AF). Design: Prospective, longitudinal. Methods: Physical activity profiles were assessed via microtechnology (GPS and accelerometer) from 40 professional AF players from the same team during 15 Australian Football League games. Skill-performance measure and player-rank scores (Champion Data Rank) were provided by a commercial statistical provider. The physical-performance variables, skill involvements, and individual player performance scores were expressed relative to playing time for each quarter. A stepwise multiple regression was used to examine the contribution of physical activity and skill involvements to coaches' perception of performance and player rank in AF. Results: Stepwise multiple-regression analysis revealed that 42.2% of the variance in coaches' perception of a player's performance could be explained by the skill-performance characteristics (player rank/min, effective kicks/min, pressure points/min, handballs/min, and running bounces/ min), with a small contribution from physical activity measures (accelerations/min) (adjusted R2 = .422, F6,282 = 36.054, P < .001). Multiple regression also revealed that 66.4% of the adjusted variance in player rank could be explained by total disposals/min, effective kicks/min, pressure points/min, kick clangers/min, marks/min, speed (m/min), and peak speed (adjusted R2 = .664, F7,281 = 82.289, P < .001). Increased physical activity throughout a match (speed [m/min] β - 0.097 and peak speed β - 0.116) negatively affects player rank in AF. Conclusions: Skill performance rather than increased physical activity is more important to coaches' perception of performance and player rank in professional AF. © 2014 Human Kinetics, Inc