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The Effect of Adding Caffeine to Postexercise Carbohydrate Feeding on Subsequent High-Intensity Interval-Running Capacity Compared With Carbohydrate Alone

Conor Taylor, Daniel Higham, Graeme L. Close, and James P. Morton

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.

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β-Alanine Improves Punch Force and Frequency in Amateur Boxers During a Simulated Contest

Tim Donovan, Tim Ballam, James P. Morton, and Graeme L. Close

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.

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Male Flat Jockeys Do Not Display Deteriorations in Bone Density or Resting Metabolic Rate in Accordance With Race Riding Experience: Implications for RED-S

George Wilson, Dan Martin, James P. Morton, and Graeme L. Close

Despite consistent reports of poor bone health in male jockeys, it is not yet known if this is a consequence of low energy availability or lack of an osteogenic stimulus. Given the rationale that low energy availability is a contributing factor in low bone health, we tested the hypothesis that both hip and lumbar bone mineral density (BMD) should progressively worsen in accordance with the years of riding. In a cross-sectional design, male apprentice (n = 17) and senior (n = 14) jockeys (matched for body mass and fat-free mass) were assessed for hip and lumbar spine BMD, as well as both measured and predicted resting metabolic rate (RMR). Despite differences (p < .05) in years of race riding (3.4 ± 2 vs. 16.3 ± 6.8), no differences were apparent (p > .05) in hip (−0.9 ± 1.1 vs. −0.8 ± 0.7) and lumbar Z-scores (−1.3 ± 1.4 vs. −1.5 ± 1) or measured RMR (1,459 ± 160 vs. 1,500 ± 165 kcal/day) between apprentices and senior jockeys, respectively. Additionally, years of race riding did not demonstrate any significant correlations (p > .05) with either hip or lumbar spine BMD. Measured RMR was also not different (p > .05) from predicted RMR in either apprentice (1,520 ± 44 kcal/day) or senior jockeys (1,505 ± 70 kcal/day). When considered with previously published data examining underreporting of energy intake and direct assessments of energy expenditure, we suggest that low BMD in jockeys is not due to low energy availability per se but rather the lack of an osteogenic stimulus associated with riding.

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Nutrition for the Prevention and Treatment of Injuries in Track and Field Athletes

Graeme L. Close, Craig Sale, Keith Baar, and Stephane Bermon

Injuries are an inevitable consequence of athletic performance with most athletes sustaining one or more during their athletic careers. As many as one in 12 athletes incur an injury during international competitions, many of which result in time lost from training and competition. Injuries to skeletal muscle account for over 40% of all injuries, with the lower leg being the predominant site of injury. Other common injuries include fractures, especially stress fractures in athletes with low energy availability, and injuries to tendons and ligaments, especially those involved in high-impact sports, such as jumping. Given the high prevalence of injury, it is not surprising that there has been a great deal of interest in factors that may reduce the risk of injury, or decrease the recovery time if an injury should occur: One of the main variables explored is nutrition. This review investigates the evidence around various nutrition strategies, including macro- and micronutrients, as well as total energy intake, to reduce the risk of injury and improve recovery time, focusing upon injuries to skeletal muscle, bone, tendons, and ligaments.

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N-Acetylcysteine’s Attenuation of Fatigue After Repeated Bouts of Intermittent Exercise: Practical Implications for Tournament Situations

James N. Cobley, Chris McGlory, James P. Morton, and Graeme L. Close

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.

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Vitamin C Consumption Does Not Impair Training-Induced Improvements in Exercise Performance

Llion A. Roberts, Kris Beattie, Graeme L. Close, and James P. Morton

Purpose:

To test the hypothesis that antioxidants can attenuate high-intensity interval training–induced improvements in exercise performance.

Methods:

Two groups of recreationally active males performed a high-intensity interval running protocol, four times per week for 4 wk. Group 1 (n = 8) consumed 1 g of vitamin C daily throughout the training period, whereas Group 2 (n = 7) consumed a visually identical placebo. Pre- and posttraining, subjects were assessed for VO2max, 10 km time trial, running economy at 12 km/h and distance run on the YoYo intermittent recovery tests level 1 and 2 (YoYoIRT1/2). Subjects also performed a 60 min run before and after training at a running velocity of 65% of pretraining VO2max so as to assess training-induced changes in substrate oxidation rates.

Results:

Training improved (P < .0005) VO2max, 10 km time trial, running economy, YoYoIRT1 and YoYoIRT2 in both groups, although there was no difference (P = .31, 0.29, 0.24, 0.76 and 0.59) between groups in the magnitude of training-induced improvements in any of the aforementioned parameters. Similarly, training also decreased (P < .0005) mean carbohydrate and increased mean fat oxidation rates during submaximal exercise in both groups, although no differences (P = .98 and 0.94) existed between training conditions.

Conclusions:

Daily oral consumption of 1 g of vitamin C during a 4 wk high-intensity interval training period does not impair training-induced improvements in the exercise performance of recreationally active males.

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“Food First but Not Always Food Only”: Recommendations for Using Dietary Supplements in Sport

Graeme L. Close, Andreas M. Kasper, Neil P. Walsh, and Ronald J. Maughan

The term “food first” has been widely accepted as the preferred strategy within sport nutrition, although there is no agreed definition of this and often limited consideration of the implications. We propose that food first should mean “where practically possible, nutrient provision should come from whole foods and drinks rather than from isolated food components or dietary supplements.” There are many reasons to commend a food first strategy, including the risk of supplement contamination resulting in anti-doping violations. However, a few supplements can enhance health and/or performance, and therefore a food only approach could be inappropriate. We propose six reasons why a food only approach may not always be optimal for athletes: (a) some nutrients are difficult to obtain in sufficient quantities in the diet, or may require excessive energy intake and/or consumption of other nutrients; (b) some nutrients are abundant only in foods athletes do not eat/like; (c) the nutrient content of some foods with established ergogenic benefits is highly variable; (d) concentrated doses of some nutrients are required to correct deficiencies and/or promote immune tolerance; (e) some foods may be difficult to consume immediately before, during or immediately after exercise; and (f) tested supplements could help where there are concerns about food hygiene or contamination. In these situations, it is acceptable for the athlete to consider sports supplements providing that a comprehensive risk minimization strategy is implemented. As a consequence, it is important to stress that the correct terminology should be “food first but not always food only.”

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An Assessment of the Validity of the Remote Food Photography Method (Termed Snap-N-Send) in Experienced and Inexperienced Sport Nutritionists

Reuben G. Stables, Andreas M. Kasper, S. Andy Sparks, James P. Morton, and Graeme L. Close

The remote food photography method, often referred to as “Snap-N-Send” by sport nutritionists, has been reported as a valid method to assess energy intake in athletic populations. However, preliminary studies were not conducted in true free-living conditions, and dietary assessment was performed by one researcher only. The authors, therefore, assessed the validity of Snap-N-Send to assess the energy and macronutrient composition in experienced (EXP, n = 23) and inexperienced (INEXP, n = 25) sport nutritionists. The participants analyzed 2 days of dietary photographs, comprising eight meals. Day 1 consisted of “simple” meals based around easily distinguishable foods (i.e., chicken breast and rice), and Day 2 consisted of “complex” meals, containing “hidden” ingredients (i.e., chicken curry). The estimates of dietary intake were analyzed for validity using one-sample t tests and typical error of estimates (TEE). The INEXP and EXP nutritionists underestimated energy intake for the simple day (mean difference [MD] = −1.5 MJ, TEE = 10.1%; −1.2 MJ, TEE = 9.3%, respectively) and the complex day (MD = −1.2 MJ, TEE = 17.8%; MD = −0.6 MJ, 14.3%, respectively). Carbohydrate intake was underestimated by INEXP (MD = −65.5 g/day, TEE = 10.8% and MD = −28.7 g/day, TEE = 24.4%) and EXP (MD = −53.4 g/day, TEE = 10.1% and −19.9 g/day, TEE = 17.5%) for both the simple and complex days, respectively. Interpractitioner reliability was generally “poor” for energy and macronutrients. The data demonstrate that the remote food photography method/Snap-N-Send underestimates energy intake in simple and complex meals, and these errors are evident in the EXP and INEXP sport nutritionists.

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GB Apprentice Jockeys Do Not Have the Body Composition to Make Current Minimum Race Weights: Is It Time to Change the Weights or Change the Jockeys?

George Wilson, Jerry Hill, Daniel Martin, James P. Morton, and Graeme L. Close

Flat jockeys in Great Britain (GB) are classified as apprentices if they are aged less than 26 years and/or have ridden less than 95 winners. To gain experience, apprentices are allocated a weight allowance of up to 7 lb (3.2 kg). Given that there is no off-season in GB flat horseracing, jockeys are required to maintain their racing weight all year round. In light of recent work determining that current apprentices are considerably heavier than previous generations and that smaller increases have been made in the minimum weight, the aim of this study was to assess if the minimum weight in GB was achievable. To make the minimum weight (50.8 kg) with the maximal weight allowance requires a body mass of ∼46.6 kg while maintaining a fat mass >2.5 kg (the lowest fat mass previously reported in weight-restricted males). Thirty-two male apprentice jockeys were assessed for body composition using dual-energy X-ray absorptiometry. The mean (SD) total mass and fat mass were 56 (2.9) kg and 7.2 (1.8) kg, respectively. Given that the lowest theoretical body mass for this group was 51.2 (2.3) kg, only one of 32 jockeys was deemed feasible to achieve the minimum weight with their current weight allowance and maintaining fat mass >2.5 kg. Furthermore, urine osmolality of 780 (260) mOsmol/L was seen, with 22 (out of 32) jockeys classed as dehydrated (>700 mOsmols/L), indicating that body mass would be higher when euhydrated. Additionally, we observed that within new apprentice jockeys licensed during this study (N = 41), only one jockey was able to achieve the minimum weight. To facilitate the goal of achieving race weight with minimal disruptions to well-being, the authors’ data suggest that the minimum weight for GB apprentices should be raised.

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Energy Expenditure of Elite Male and Female Professional Tennis Players During Habitual Training

Daniel G. Ellis, James P. Morton, Graeme L. Close, and Tim F. Donovan

Understanding the daily energy expenditure of athletes during training is important to support recovery, adaptation, and the maintenance of performance. The aim of the current research was to assess the total daily energy expenditure (TDEE) and the acute energy expenditure (EE) of tennis training sessions during habitual training of elite tennis players. Using a cohort study design, 27 (n = 10, male; age; 22.3 ± 3.2 years and n = 17, female; age: 23.8 ± 3.5 years) elite singles tennis players were assessed for TDEE and tennis training EE. Using Actiheart activity monitors during a 2- to 5-day training period, male players were analyzed for 26 days and 33 (1.3 ± 0.5 sessions/day) tennis training sessions, and female players for 43 days and 58 (1.2 ± 0.4 sessions/day) tennis training sessions. Male TDEE (4,708 ± 583 kcal/day) was significantly higher than female (3,639 ± 305 kcal/day). Male absolute and relative tennis training EEs (10.2 ± 2.3 kcal/min and 7.9 ± 1.4 kcal·hr−1·kg−1) were significantly higher than those of females (7.6 ± 1.0 kcal/min and 6.8 ± 0.9 kcal·hr−1·kg−1). The resting metabolic rate was assessed via indirect calorimetry. The physical activity level for both groups was 2.3 AU. The TDEE of male and female players during habitual training now highlights the continual cycle of high energy demands experienced by the elite tennis player. The broad ranges of TDEE and EE reported here suggest individual assessment and nutritional planning be prioritized, with a particular focus on carbohydrate requirements.