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Is a Four-Week Ketogenic Diet an Effective Nutritional Strategy in CrossFit-Trained Female and Male Athletes?
Durkalec-Michalski, K, Nowaczyk, PM, Główka, N, Ziobrowska, A, Podgórski, T
Nutrients. 2021;(3)
Abstract
This single-arm interventional study examined the effect of a 4-week ketogenic diet (KD) on aerobic capacity and discipline-specific performance in female (n = 11) and male (n = 11) CrossFit-trained athletes. The participants performed incremental cycling (ICT) and Fight Gone Bad (FGB) tests after consuming a customary diet and a KD. Pre- and post-ICT exercise blood samples were also analysed. Consuming a KD had a slight impact on aerobic capacity and no relevant effect on CrossFit-specific performance. In females, consuming a KD led to an 10.4% decrease in peak oxygen uptake during the ICT (p = 0.027) and resulted in certain alterations in haematological parameters (haemoglobin (HGB), mean corpuscular HGB, and mean corpuscular HGB concentration). Furthermore, in males, alanine aminotransferase activity increased with a simultaneous improvement in the post-ICT blood acid-base balance after consuming a KD. The pre-exercise bilirubin concentration was also elevated in the entire group after consuming a KD. In conclusion, female CrossFit-trained athletes seem to be prone to aerobic performance decrements and increased risk of developing haematological disturbances when consuming a KD. In males who consumed a KD, there was an undesirable alanine aminotransferase elevation and a small tendency towards improved acid-base status. Moreover, consuming a KD had no effect on discipline-specific performance in CrossFit-trained athletes.
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Effects of whole-body cryotherapy on 25-hydroxyvitamin D, irisin, myostatin, and interleukin-6 levels in healthy young men of different fitness levels.
Śliwicka, E, Cisoń, T, Straburzyńska-Lupa, A, Pilaczyńska-Szcześniak, Ł
Scientific reports. 2020;(1):6175
Abstract
Skeletal muscle and adipose tissue play an important role in maintaining metabolic homeostasis and thermogenesis. We aimed to investigate the effects of single and repeated exposure to whole-body cryotherapy in volunteers with different physical fitness levels on 25-hydroxyvitamin D (25(OH)D) and myokines. The study included 22 healthy male volunteers (mean age: 21 ± 1.17 years), who underwent 10 consecutive sessions in a cryogenic chamber once daily (3 minutes, -110 °C). Blood samples were collected before and 30 minutes and 24 hours after the first and last cryotherapy sessions. Prior to treatment, body composition and physical fitness levels were measured. After 10 cryotherapy treatments, significant changes were found in myostatin concentrations in the low physical fitness level (LPhL) group. The 25(OH)D levels were increased in the high physical fitness level (HPhL) group and decreased in the LPhL group. The HPhL group had significant changes in the level of high-sensitivity interleukin-6 after the first treatment. The LPhL group had significant changes in 25(OH)D, irisin, and myostatin levels after the tenth treatment. Our data demonstrated that in healthy young men, cryotherapy affects 25(OH)D levels, but they were small and transient. The body's response to a series of 10 cryotherapy treatments is modified by physical fitness level.
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The gender dependent influence of sodium bicarbonate supplementation on anaerobic power and specific performance in female and male wrestlers.
Durkalec-Michalski, K, Zawieja, EE, Zawieja, BE, Michałowska, P, Podgórski, T
Scientific reports. 2020;(1):1878
Abstract
The aim of this study was the assessment of progressive low-dose sodium bicarbonate (NaHCO3) supplementation on the anaerobic indices in two bouts of Wingate tests (WT) separated by wrestling-specific performance test and assessing the gender differences in response. Fifty-one (18 F) wrestlers completed a randomized trial of either a NaHCO3 (up to 100 mg·kg-1) or a placebo for 10 days. Before and after treatment, athletes completed an exercise protocol that comprised, in sequence, the first WT1, dummy throw test (DT), and second WT2. The number of completed throws increased significantly in males from 19.3 ± 2.6 NaHCO3pre to 21.7 ± 2.9 NaHCO3post. ΔWT2-WT1 improved particularly in the midsection of 30-s WT on NaHCO3. However, no significant differences were found in peak power (PP), power drop (PD) and average power (AP) (analyzed separately for each WT), and ΔWT2-WT1 in PP and PD. Interaction with gender was significant for AP, PP and PD, every second of WT1 and WT2, as well as DT test. In conclusion, our study suggests that the response to NaHCO3 may be gender-specific and progressive low-dose NaHCO3 supplementation allows the advantageous strengthening of wrestling-specific performance in males. It can also lead to maintenance of high anaerobic power mainly in the midsection of the 30-s Wingate test.
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The influence of D-ribose ingestion and fitness level on performance and recovery.
Seifert, JG, Brumet, A, St Cyr, JA
Journal of the International Society of Sports Nutrition. 2017;:47
Abstract
BACKGROUND Skeletal muscle adenosine triphosphate (ATP) levels are severely depleted during and following prolonged high intensity exercise. Recovery from these lower ATP levels can take days, which can affect performance on subsequent days of exercise. Untrained individuals often suffer the stress and consequences of acute, repeated bouts of exercise by not having the ability to perform or recovery sufficiently to exercise on subsequent days. Conversely, trained individuals may be able to recover more quickly due to their enhanced metabolic systems. D-Ribose (DR) has been shown to enhance the recovery in ATP; however, it is not known if recovery and performance can be benefitted with DR ingestion. Therefore, this study was designed to determine what influence DR might have on muscular performance, recovery, and metabolism during and following a multi-day exercise regimen. METHODS The study was a double blind, crossover study in 26 healthy subjects compared 10 g/day of DR to 10 g/day of dextrose (DEX, control). All subjects completed 2 days of loading with either DR or DEX, followed by 3 additional days of supplementation and during these 3 days of supplementation, each subject underwent 60 min of high intensity interval exercise in separate daily sessions, which involved cycling (8 min of exercise at 60% and 2 min at 80% VO2max), followed by a 2 min power output (PO) test. Subjects were divided into two groups based on peak VO2 results, lower VO2 (LVO2) and higher peak VO2 (HVO2). RESULTS Mean and peak PO increased significantly from day 1 to day 3 for the DR trial compared to DEX in the LVO2 group. Rate of perceived exertion (RPE) and creatine kinase (CK) were significantly lower for DR than DEX in the LVO2 group. No differences in PO, RPE, heart rate, CK, blood urea nitrogen, or glucose were found between either supplement for the HVO2 group. CONCLUSION DR supplementation in the lower VO2 max group resulted in maintenance in exercise performance, as well as lower levels of RPE and CK. Unlike no observed benefits with DEX supplementation.
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Ingesting a high-dose carbohydrate solution during the cycle section of a simulated Olympic-distance triathlon improves subsequent run performance.
McGawley, K, Shannon, O, Betts, J
Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. 2012;(4):664-71
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Abstract
The well-established ergogenic benefit of ingesting carbohydrates during single-discipline endurance sports has only been tested once within an Olympic-distance (OD) triathlon. The aim of the present study was to compare the effect of ingesting a 2:1 maltodextrin/fructose solution with a placebo on simulated OD triathlon performance. Six male and 4 female amateur triathletes (age, 25 ± 7 years; body mass, 66.8 ± 9.2 kg; peak oxygen uptake, 4.2 ± 0.6 L·min(-1)) completed a 1500-m swim time-trial and an incremental cycle test to determine peak oxygen uptake before performing 2 simulated OD triathlons. The swim and cycle sections of the main trials were of fixed intensities, while the run section was completed as a time-trial. Two minutes prior to completing every quarter of the cycle participants consumed 202 ± 20 mL of either a solution containing 1.2 g·min(-1) of maltodextrin plus 0.6 g·min(-1) of fructose at 14.4% concentration (CHO) or a sugar-free, fruit-flavored drink (PLA). The time-trial was 4.0% ± 1.3% faster during the CHO versus PLA trial, with run times of 38:43 ± 1:10 min:s and 40:22 ± 1:18 min:s, respectively (p = 0.010). Blood glucose concentrations were higher in the CHO versus PLA trial (p < 0.001), while perceived stomach upset did not differ between trials (p = 0.555). The current findings show that a 2:1 maltodextrin/fructose solution (1.8 g·min(-1) at 14.4%) ingested throughout the cycle section of a simulated OD triathlon enhances subsequent 10-km run performance in triathletes.
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Carbohydrate-electrolyte drink ingestion and skill performance during and after 2 hr of indoor tennis match play.
McRae, KA, Galloway, SD
International journal of sport nutrition and exercise metabolism. 2012;(1):38-46
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Abstract
Twenty-two tennis players were individually studied on 2 occasions. They performed a prematch skill test, a 2-hr tennis match against an equally ranked opponent, and a postmatch skill test. A carbohydrate-electrolyte (CHO-E; Lucozade Sport) or flavor-matched placebo-electrolyte (PL) beverage was administered in a double-blind fashion. During the trials, heart-rate and movement intensity were monitored, and the match was recorded for performance analysis. There were no differences in skill-test scores pre- to postmatch or between trials (154±38 pre- and 160±35 postmatch on PL, 155±36 pre- and 165±33 postmatch on CHO-E). CHO-E ingestion elevated blood glucose concentration throughout the match, and participants reported feeling more energetic (general activation) and more tense (high activation) 1 hr into the match than at baseline (p<.05). Participants in the CHO-E trial spent more time in moderate-intensity activity and less time in low-intensity activity than on PL. Performance analysis revealed that CHO-E ingestion increased overall serve success (M±SD, 68%±7% for CHO-E vs. 66%±7% for PL; p<.05) and success of first serves (65%±9% for CHO-E, 61%±7% for PL; p<.01) and serves to the advantage side (70%±9% for CHO-E, 66%±7% for PL; p<.05). Return success was greater during the second set of the match (p<.05) in the CHO-E trial. Differences in serve and return success were not associated with blood glucose response to CHO or player ability.
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Magnesium intake is associated with strength performance in elite basketball, handball and volleyball players.
Santos, DA, Matias, CN, Monteiro, CP, Silva, AM, Rocha, PM, Minderico, CS, Bettencourt Sardinha, L, Laires, MJ
Magnesium research. 2011;(4):215-9
Abstract
Magnesium plays significant roles in promoting strength. Surveys of athletes reveal that intake of magnesium is often below recommended levels. We aimed to understand the impact of magnesium intake on strength in elite male basketball, handball, and volleyball players. Energy and nutrient intake were assessed from seven-day diet record. Strength tests included maximal isometric trunk flexion, extension, and rotation, handgrip, squat and countermovement Abalakov jump, and maximal isokinetic knee extension and flexion peak torques. Linear regression models were performed with significance at p<0.1. Mean magnesium intake was significantly lower than the recommended daily allowance. Regression analysis indicated that magnesium was directly associated with maximal isometric trunk flexion, rotation, and handgrip, with jumping performance tests, and with all isokinetic strength variables, independent of total energy intake. The observed associations between magnesium intake and muscle strength performance may result from the important role of magnesium in energetic metabolism, transmembrane transport and muscle contraction and relaxation.
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Effects of carbohydrate and caffeine ingestion on performance during a rugby union simulation protocol.
Roberts, SP, Stokes, KA, Trewartha, G, Doyle, J, Hogben, P, Thompson, D
Journal of sports sciences. 2010;(8):833-42
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Abstract
In this study, we investigated the effect of ingesting carbohydrate alone or with caffeine on performance of a rugby union-specific shuttle running protocol. On three occasions, at least one week apart in a counterbalanced trial order, eight male rugby union forwards ingested either placebo or carbohydrate (1.2 g x kg(-1) body mass x h(-1)) before and during a rugby union-specific protocol, with pre-exercise caffeine ingestion (4 mg x kg(-1)) before one of the carbohydrate trials (carbohydrate + caffeine). The intermittent exercise protocol included walking, jogging, and cruising at pre-determined intensities, simulated contact events, a sustained high-intensity test of speed and agility (Performance Test), and a 15-m sprint. Ratings of perceived exertion (RPE) were recorded every 5 min and a motor skills test was performed after each 21-min block. Performance Test times were not significantly different between trials but the likelihood of 2% improvements for carbohydrate + caffeine over placebo and carbohydrate were 98% and 44%, respectively. For carbohydrate + caffeine, 15-m sprints were faster than for placebo (P=0.05) and the motor skills test was performed faster in the carbohydrate + caffeine trial than the carbohydrate and placebo trials (P < 0.05), while RPE was lower in the carbohydrate + caffeine trial than the carbohydrate and placebo trials (P < 0.05). The results indicate a likely benefit to rugby performance following co-ingestion of carbohydrate and caffeine.