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The aim of this study was to determine the effects of postexercise ingestion of different-molecular-weight glucose polymer solutions on subsequent high-intensity interval-running capacity. In a repeated-measures design, 6 men ran for 60 min in the morning at 70% VO_2max. Immediately post- and at 1 and 2 hr postexercise, participants consumed a 15% low-molecular-weight (LMW) or high-molecular-weight (HMW) carbohydrate solution, at a rate of 1.2 g of carbohydrate/kg body mass, or an equivalent volume of flavored water (WAT). After recovery, participants performed repeated 1-min intervals at 90% VO_2max interspersed with 1 min active recovery (walking) until volitional exhaustion. Throughout the 3-hr recovery period, plasma glucose concentrations were higher (p = .002) during the HMW and LMW conditions than with WAT (M 7.0 ± 0.8, 7.5 ± 1.0, and 5.6 ± 0.2 mmol/L, respectively), although there was no difference (p = .723) between HMW and LMW conditions. Exercise capacity was 13 (43 ± 10 min; 95% CI for differences: 8–18; p = .001) and 11 min (41 ± 9 min; 95% CI for differences; 2–18: p = .016) longer with HMW and LMW solutions, respectively, than with WAT (30 ± 9 min). There was no substantial difference (2 min; 95% CI for differences: –5 to 10; p = .709) in exercise capacity between LMW and HMW solutions. Although this magnitude of difference is most likely trivial in nature, the uncertainty allows for a possible small substantial enhancement of physiological significance, and further research is required to clarify the true nature of the effect.

The provision of exogenous carbohydrate (CHO) in the form of energy gels is regularly practiced among endurance and team sport athletes. However, in those instances where athletes ingest suboptimal fluid intake, consuming gels during exercise may lead to gastrointestinal (GI) problems when the nutritional composition of the gel is not aligned with promoting gastric emptying. Accordingly, the aim of the current study was to quantify the degree of diversity in nutritional composition of commercially available CHO gels intended for use in the global sports nutrition market. We surveyed 31 product ranges (incorporating 51 flavor variants) from 23 brands (Accelerade, CNP, High5, GU, Hammer, Maxim, Clif, USN, Mule, Multipower, Nectar, Carb-Boom, Power Bar, Lucozade, Shotz, TORQ, Dextro, Kinetica, SiS, Zipvit, Maxifuel, Gatorade and Squeezy). Gels differed markedly in serving size (50 ± 22 g: 29–120), energy density (2.34 ± 0.7 kcal/g: 0.83–3.40), energy content (105 ± 24 kcal: 78–204), CHO content (26 ± 6 g: 18–51) and free sugar content (9.3 ± 7.0 g: 0.6–26.8). Most notably, gels displayed extreme variation in osmolality (4424 ± 2883 mmol/kg: 303–10,135) thereby having obvious implications for both GI discomfort and the total fluid intake likely required to optimize CHO delivery and oxidation. The large diversity of nutritional composition of commercially available CHO gels illustrate that not all gels should be considered the same. Sports nutrition practitioners should therefore consider the aforementioned variables to make better-informed decisions regarding which gel product best suits the athlete’s specific fueling and hydration requirements.

Body mass (BM) manipulation via rapid weight loss (RWL) and rapid weight gain (RWG) is a common practice among mixed martial art (MMA) athletes to ensure qualification for the division in which the athlete wishes to compete. Professional MMA competitors in California are required to weigh in twice: 24 hr prior to competition and immediately prior to the bout after they have typically engaged in RWG. In analyzing data from five MMA events sanctioned by the Californian State Athletic Commission, the authors used Bayesian analyses to compare bout winners (n = 62) and losers (n = 62) in terms of in-competition BM (in kilograms) and the amount of BM regained between the two weigh-ins (in kilograms). These data do not support the hypothesis that differences in in-competition BM (Bayes factor [BF₁₀] = 0.667, d = 0.23) or the amount of BM regained between the two weigh-ins (BF₁₀ = 0.821, d = 0.23) determine winning or losing. In addition, there was no statistical difference between bouts ending via strikes, submission, or decision for either in-competition BM (BF₁₀ = 0.686, ω² < 0.01) or the amount of BM regained between the two weigh-ins (BF₁₀ = 0.732, ω² = 0.054). In conclusion, the authors report for the first time that the magnitude of RWG does not predict winning or losing in a professional cohort of MMA athletes. In addition, they also report that MMA athletes typically compete at a BM that is at least 1–2 divisions higher than the division in which they officially weighed-in. These analyses may provide impetus for governing bodies and coaches to enact changes at both professional and amateur levels to reduce negative health consequences associated with extreme RWL and RWG.

Professional boxing is a combat sport categorized into a series of weight classes. Given the sport’s underpinning culture, boxers’ typical approach to “making weight” is usually via severe acute and/or chronic energy restriction and dehydration. Such practices have implications for physical performance and also carry health risks. This article provides a case-study account outlining a more structured and gradual approach to helping a professional male boxer make weight for the 59-kg superfeatherweight division. Over a 12-week period, the client athlete adhered to a daily diet approximately equivalent to his resting metabolic rate (6–7 MJ; 40% carbohydrate, 38% protein, 22% fat). Average body-mass loss was 0.9 ± 0.4 kg/wk, equating to a total loss of 9.4 kg. This weight loss resulted in a decrease in percent body fat from 12.1% to 7.0%. In the 30 hr between weigh-in and competition, the client consumed a high-carbohydrate diet (12 g/kg body mass) supported by appropriate hydration strategies and subsequently entered the ring at a fighting weight of 63.2 kg. This nutritional strategy represented a major change in the client’s habitual weight-making practices and did not rely on any form of intended dehydration during the training period or before weighing in. The intervention demonstrates that a more gradual approach to making weight in professional boxing can be successfully achieved via a combination of restricted energy intake and increased energy expenditure, providing there is willingness on the part of the athlete and coaches involved to adopt novel practices.

The aim of this study was to test the hypothesis that adding caffeine to postexercise carbohydrate (CHO) feedings improves subsequent high-intensity interval-running capacity compared with CHO alone. In a repeated-measures design, 6 men performed a glycogen-depleting exercise protocol until volitional exhaustion in the morning. Immediately after and at 1, 2, and 3 hr postexercise, participants consumed 1.2 g/kg body mass CHO of a 15% CHO solution, a similar CHO solution but with addition of 8 mg/kg body mass of caffeine (CHO+CAFF), or an equivalent volume of flavored water only (WAT). After the 4-hr recovery period, participants performed the Loughborough Intermittent Shuttle Test (LIST) to volitional exhaustion as a measure of high-intensity interval-running capacity. Average blood glucose values during the 4-hr recovery period were higher in the CHO conditions (p < .005) than in the WAT trial (4.6 ± 0.3 mmol/L), although there was no difference (p = .46) between CHO (6.2 ± 0.8 mmol/L) and CHO+CAFF (6.7 ± 1.0 mmol/L). Exercise capacity during the LIST was significantly longer in the CHO+CAFF trial (48 ± 15 min) than in the CHO (32 ± 15 min, p = .04) and WAT conditions (19 ± 6 min, p = .001). All 6 participants improved performance in CHO+CAFF compared with CHO (95% CI for mean difference = 1–32 min). The study provides novel data by demonstrating that adding caffeine to postexercise CHO feeding improves subsequent high-intensity interval-running capacity, a finding that may be related to higher rates of postexercise muscle glycogen resynthesis previously observed under similar feeding conditions.

The aim of this study was to test the hypothesis that β-alanine supplementation improves punch power and frequency in amateur boxers during a simulated contest. Sixteen amateur boxers (each approximately 6 yr experience) were assigned to β-alanine (n = 8; 1.5 g 4 times/d for 4 wk) or placebo supplementation (n = 8) after initially being assessed for baseline punch performance. Before and after the supplementation period, all boxers completed a simulated contest consisting of 3 × 3-min rounds (interspersed with 60-s rests) on a punching bag (with a force transducer attached). Each round involved performing 2 min 50 s standardized punching (standardized jab, cross combination) based on notation analysis, whereas the last 10 s involved maximal-output punching (standardized jab, cross combination), during which time punch force and frequency were recorded. Postcontest blood lactate was significantly increased in the β-alanine group (presupplementation 9.5 ± 0.9 mmol/L, postsupplementation 12.6 ± 0.5 mmol/L, p < .05), whereas the placebo group showed no change (presupplementation 8 ± 2.8 mmol/L, postsupplementation 7.0 ± 2.7 mmol/L; p > .05). During the 10-s maximal-output punching, changes in mean punch force (β-alanine 20 ± 1.01 kg, placebo 1 ± 1 kg) and punch frequency (β-alanine 5 ± 4, placebo –2 ± 3) were greater (p < .05) in the β-alanine-supplemented group. The authors conclude that β-alanine supplementation improves punching performance in amateur boxers and suggest that this supplementation protocol may also prove ergogenic for other combat-related sports.

Production of reactive oxygen species (ROS) during muscle contractions is associated with muscle fatigue and damage in the short term and adaptive responses in the long term. When adaptation is inconsequential acute antioxidant supplementation may be able to attenuate muscle fatigue and damage to enhance performance. This study aimed to determine the effects of acute oral N-acetylcysteine (NAC) supplementation on Yo-Yo Intermittent Recovery Test Level 1 (YIRT-L1) performance after repeated bouts of damaging intermittent exercise. In a pair-matched design, 12 recreationally trained men engaged in 6 d of either NAC (n = 6) or placebo (n = 6) supplementation. After a treatment-loading day, participants completed 3 testing sessions, on alternating days, consisting of a preexercise isokinetic dynamometry (IKD) test, a damaging intermittent-exercise protocol, YIRT-L1, and a postexercise IKD test. Another IKD test was completed on the 2 intervening d. NAC treatment resulted in a significant preservation of YIRT-L1 performance (p ≤ .0005). IKD performance significantly deteriorated over time at all contraction speeds, and this deterioration was not influenced by treatment group. Plasma creatine kinase values increased significantly over time (p = .002) and were significantly greater in the NAC group than in the placebo group (p = .029). NAC induced mild gastrointestinal side effects. NAC supplementation may be a useful strategy to enhance performance during short-term competitive situations when adaption is inconsequential. Titration studies to elucidate a treatment dose that enhances performance without inducing side effects are now required.