Athletes involved in contact sports are habitually exposed to skeletal-muscle damage in their training and performance environments. This often leads to exercise-induced muscle damage (EIMD) resulting from repeated eccentric and/or high-intensity exercise and to impact-induced muscle damage (IIMD) resulting from collisions with opponents and the playing surface. While EIMD has been an area of extensive investigation, IIMD has received comparatively little research, with the magnitude and time frame of alterations following IIMD not presently well understood. It is currently thought that EIMD results from an overload of mechanical stress that causes ultrastructural damage to the cellular membrane constituents. Damage leads to compromised ability to produce force, which manifests immediately and persists for up to 14 d following exercise exposure. IIMD has been implicated in attenuated neuromuscular performance and recovery and in inflammatory processes, although the underlying course over time remains unclear. Exposure to EIMD leads to an adaptation to subsequent exposures, a phenomenon known as the repeated-bout effect. An analogous adaptation has been suggested to occur following IIMD; however, to date, this contention remains equivocal. While a considerable body of research has explored the efficacy of recovery strategies following EIMD, strategies promoting recovery from IIMD are limited to investigations using animal contusion models. Strategies such as cryotherapy and antioxidant supplementation that focus on attenuating the secondary inflammatory response may provide additional benefit in IIMD and are explored herein. Further research is required to first establish a model of generating IIMD and then explore broader areas around IIMD in athletic populations.
Mitchell Naughton, Joanna Miller, and Gary J. Slater
Gregory Shaw, Gary Slater, and Louise M. Burke
This study examined the influence the Australian Institute of Sport (AIS) Sport Supplement Program had on supplement practices of elite Australian swimmers, comparing those guided by the Program with others in the same national team. Thirty-nine elite swimmers (13 AIS, 26 Other; 20 female, 19 male; age 21.8 ± 3.3 y) completed a questionnaire investigating supplement use. Ninety-seven percent of swimmers reported taking supplements or sports foods over the preceding 12 months. AIS swimmers reported using more total brands (p = .02) and supplements considered Ergogenic (p = .001) than Other swimmers who used more supplements considered to be lacking scientific support (p = .028). Swimmers rated the risk of a negative outcome from the use of supplements available in Australia (Mdn = 3.0) as less than the risk of supplements from international sources (Mdn = 4.0; p < .001). AIS swimmers were more likely to report dietitians (p < .001) and sports physicians (p = .017) as advisors of their supplement use. Other swimmers more frequently reported fellow athletes as a source of supplement advice (p = .03). AIS swimmers sourced a greater percentage of their supplements from an organized program (94 ± 16%) compared with Other (40 ± 32%; p < .001) who sourced a greater percentage (30 ± 30%) of their dietary supplements from supermarkets. These findings suggest that swimmers influenced by this sport supplement program more frequently use supplements that are recommended by allied health trained individuals, classified as evidence based and provided by the program.
Gary J. Slater, Jennifer Sygo, and Majke Jorgensen
Although sprint athletes are assumed to primarily be interested in promoting muscle hypertrophy, it is the ability to generate explosive muscle power, optimization of power-to-weight ratio, and enhancement of anaerobic energy generation that are key outcomes of sprint training. This reflects the physique of track sprinters, being characterized as ecto-mesomorphs. Although there is little contemporary data on sprinters dietary habits, given their moderate energy requirements relative to body mass, a carbohydrate intake within the range of 3–6 g·kg−1·day−1 appears reasonable, while ensuring carbohydrate availability is optimized around training. Similarly, although protein needs may be twice general population recommendations, sprint athletes should consume meals containing ∼0.4 g/kg high biological value protein (i.e., easily digested, rich in essential amino acids) every 3–5 hr. Despite the short duration of competitions and relative long-recovery periods between races, nutrition still plays an important role in sprint performance. As energy expenditure moderates during competition, so too should intake of energy and macronutrients to prevent unwanted weight gain. Further adjustments in macronutrient intake may be warranted among athletes contemplating optimization of power-to-weight ratio through reductions in body fat prior to the competitive season. Other novel acute methods of weight loss have also been proposed to enhance power-to-weight ratio, but their implementation should only be considered under professional guidance. Given the metabolic demands of sprinting, a few supplements may be of benefit to athletes in training and/or competition. Their use in competition should be preceded with trialing in training to confirm tolerance and perceived ergogenic potential.
Reid Reale, Gary Slater, and Louise M. Burke
It is common for athletes in weight-category sports to try to gain a theoretical advantage by competing in weight divisions that are lower than their day-to-day body mass (BM). Weight loss is achieved not only through chronic strategies (body-fat losses) but also through acute manipulations before weigh-in (“making weight”). Both have performance implications. This review focuses on Olympic combat sports, noting that the varied nature of regulations surrounding the weigh-in procedures, weight requirements, and recovery opportunities in these sports provide opportunity for a wider discussion of factors that can be applied to other weight-category sports. The authors summarize previous literature that has examined the performance effects of weightmaking practices before investigating the physiological nature of these BM losses. Practical recommendations in the form of a decision tree are provided to guide the achievement of acute BM loss while minimizing performance decrements.
Reid Reale, Gary Slater, and Louise M. Burke
Purpose: Combat sport athletes undertake chronic and rapid weight loss (RWL) practices to qualify for weight divisions lower than their training weight. Variation between sports in the prevalence, methods, and magnitude of weight loss as well as recovery practices may be influenced by factors including competition level and culture. Differences in methodologies of previous research in combat sports make direct comparisons difficult; thus, this study aimed to examine weight loss practices among all Olympic combat sports in Australia, using standardized methodology. Methods: High-caliber competitors in wrestling, boxing, judo, and taekwondo (n = 260) at Australian competitions were surveyed using a validated tool that provides quantification of how extreme an athlete’s weight loss practices are: the rapid weight loss score (RWLS). Additional qualitative and quantitative survey data were also collected. Results: Neither sport, sex, nor weight division group had an effect on RWLS; however, a significant effect of athlete caliber was detected (F 2,215 = 4.953, mean square error = 4.757, P = .00792). Differences between sports were also evident for most weight ever lost in order to compete (H = 19.92, P = .0002), age at which weight cutting began (H = 16.34, P = .001), and selected methods/patterns of RWL (P < .001). Weight cycling between competitions was common among all sports as were influences on athlete’s behaviors. Conclusions: Although many similarities in weight loss practices and experiences exist between combat sports, specific differences were evident. Nuanced, context/culturally specific guidelines should be devised to assist fighters’ in optimizing performance while minimizing health implications.
Ava Farley, Gary J. Slater, and Karen Hind
Athletic populations require high-precision body composition assessments to identify true change. Least significant change determines technical error via same-day consecutive tests but does not integrate biological variation, which is more relevant for longitudinal monitoring. The aim of this study was to assess biological variation using least significant change measures from body composition methods used on athletes, including surface anthropometry (SA), air displacement plethysmography (BOD POD), dual-energy X-ray absorptiometry (DXA), and bioelectrical impedance spectroscopy (BIS). Thirty-two athletic males (age = 31 ± 7 years; stature = 183 ± 7 cm; mass = 92 ± 10 kg) underwent three testing sessions over 2 days using four methods. Least significant change values were calculated from differences in Day 1 Test 1 versus Day 1 Test 2 (same-day precision), as well as Day 1 Test 1 versus Day 2 (consecutive-day precision). There was high agreement between same-day and consecutive-day fat mass and fat-free mass measurements for all methods. Consecutive-day precision error in comparison with the same-day precision error was 50% higher for fat mass estimates from BIS (3,607 vs. 2,331 g), 25% higher from BOD POD (1,943 vs. 1,448 g) and DXA (1,615 vs. 1,204 g), but negligible from SA (442 vs. 586 g). Consecutive-day precision error for fat-free mass was 50% higher from BIS (3,966 vs. 2,276 g) and SA (1,159 vs. 568 g) and 25% higher from BOD POD (1,894 vs. 1,450 g) and DXA (1,967 vs. 1,461 g) than the same-day precision error. Precision error in consecutive-day analysis considers both technical error and biological variation, enhancing the identification of small, yet significant changes in body composition of resistance-trained male athletes. Given that change in physique is likely to be small in this population, the use of DXA, BOD POD, or SA is recommended.
Gregory Shaw, Gary Slater, and Louise M. Burke
Thirty nine elite Australian swimmers (13 AIS, 26 OTHER) completed a standardized questionnaire regarding their supplement use during a pre competition camp. The data were compared with a similar study conducted 11 years earlier (11 AIS, 23 OTHER) and framed around the classification system of the Sport Supplement Program of the Australian Institute of Sport. The prevalence of supplement use remained constant over time (2009: 97%, 1998: 100%). However, the current swimmers used a greater number of dietary supplements (9.2 ± 3.7 and 5.9 ± 2.9; p = .001), accounted for by an increase in the reported use of supplements with a greater evidence base (Sports Foods, Ergogenics, and Group B supplements). In contrast, fewer supplements considered less reputable (Group C and D) were reported by the 2009 cohort (0.7 ± 1.0 and 1.6 ± 1.3; p = .003). AIS swimmers reported a greater use of Ergogenics (4.3 ± 1.8 and 3.1 ± 1.7; p = .002), and less use of Group C and D supplements overall (0.8 ± 1.2 and 1.3 ± 1.2; p = .012), which was explained primarily by a smaller number of these supplements reported by the 2009 group (1998 AIS: 1.5 ± 1.4, 2009 AIS: 0.2 ± 0.6; p = .004). Although the prevalence of supplement use has not changed over time, there has been a significant increase in the number and type of products they are using. The potential that these changes can be attributed to a Sports Supplement Program merit investigation.
Gary Slater, Benedict Tan, and Kong Chuan Teh
The supplementation practices of elite athletes in Singapore were studied using an anonymous questionnaire. Information was sought on not only the type of supplements used but also dosage, rationale for use, and other factors that might influence supplement use including selected demographic parameters and sources of information relating to supplements. Data was collected from 160 athletes across a spectrum of 30 sports. Use of supplements was widespread, with 77% of respondents acknowledging use of at least 1 product. Respondents ingested a total of 59 different supplements, with each athlete using on average 3.6 ± 0.3 different products. Sports drinks, caffeine, vitamin C, multivitamin/mineral supplements, and essence of chicken were some of the most commonly ingested products, confirming that while vitamin/mineral supplements are popular, sports supplements and traditional/herbal preparations were also well accepted. Respondents preferred to source information pertaining to supplements from “significant others” and other readily accessible sources. A small number of respondents acknowledged the use of International Olympic Committee (IOC) banned or restricted substances, highlighting the need for athletes to consult sports medicine professionals with specialist knowledge of dietary supplements in advance of initiating any supplementation regime.
Adam J. Zemski, Elizabeth M. Broad, and Gary J. Slater
Body composition in elite rugby union athletes is routinely assessed using surface anthropometry, which can be utilized to provide estimates of absolute body composition using regression equations. This study aims to assess the ability of available skinfold equations to estimate body composition in elite rugby union athletes who have unique physique traits and divergent ethnicity. The development of sport-specific and ethnicity-sensitive equations was also pursued. Forty-three male international Australian rugby union athletes of Caucasian and Polynesian descent underwent surface anthropometry and dual-energy X-ray absorptiometry (DXA) assessment. Body fat percent (BF%) was estimated using five previously developed equations and compared to DXA measures. Novel sport and ethnicity-sensitive prediction equations were developed using forward selection multiple regression analysis. Existing skinfold equations provided unsatisfactory estimates of BF% in elite rugby union athletes, with all equations demonstrating a 95% prediction interval in excess of 5%. The equations tended to underestimate BF% at low levels of adiposity, whilst overestimating BF% at higher levels of adiposity, regardless of ethnicity. The novel equations created explained a similar amount of variance to those previously developed (Caucasians 75%, Polynesians 90%). The use of skinfold equations, including the created equations, cannot be supported to estimate absolute body composition. Until a population-specific equation is established that can be validated to precisely estimate body composition, it is advocated to use a proven method, such as DXA, when absolute measures of lean and fat mass are desired, and raw anthropometry data routinely to derive an estimate of body composition change.
Ava Kerr, Gary Slater, Nuala Byrne, and Janet Chaseling
The three-compartment (3-C) model of physique assessment (fat mass, fat-free mass, water) incorporates total body water (TBW) whereas the two-compartment model (2-C) assumes a TBW of 73.72%. Deuterium dilution (D2O) is the reference method for measuring TBW but is expensive and time consuming. Multifrequency bioelectrical impedance spectroscopy (BIS SFB7) estimates TBW instantaneously and claims high precision. Our aim was to compare SFB7 with D2O for estimating TBW in resistance trained males (BMI >25kg/m2). We included TBWBIS estimates in a 3-C model and contrasted this and the 2-C model against the reference 3-C model using TBWD2O. TBW of 29 males (32.4 ± 8.5 years; 183.4 ± 7.2 cm; 92.5 ± 9.9 kg; 27.5 ± 2.6 kg/m2) was measured using SFB7 and D2O. Body density was measured by BODPOD, with body composition calculated using the Siri equation. TBWBIS values were consistent with TBWD2O (SEE = 2.65L; TE = 2.6L) as were %BF values from the 3-C model (BODPOD + TBWBIS) with the 3-C reference model (SEE = 2.20%; TE = 2.20%). For subjects with TBW more than 1% from the assumed 73.72% (n = 16), %BF from the 2-C model differed significantly from the reference 3-C model (Slope 0.6888; Intercept 5.093). The BIS SFB7 measured TBW accurately compared with D2O. The 2C model with an assumed TBW of 73.72% introduces error in the estimation of body composition. We recommend TBW should be measured, either via the traditional D2O method or when resources are limited, with BIS, so that body composition estimates are enhanced. The BIS can be accurately used in 3C equations to better predict TBW and BF% in resistance trained males compared with a 2C model.