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1.
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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2.
Short-term hot water immersion results in substantial thermal strain and partial heat acclimation; comparisons with heat-exercise exposures.
Greenfield, AM, Pereira, FG, Boyer, WR, Apkarian, MR, Kuennen, MR, Gillum, TL
Journal of thermal biology. 2021;:102898
Abstract
OBJECTIVE To examine the effectiveness of hot water immersion (HWI) as a heat acclimation strategy in comparison to time and temperature matched, exercise-heat acclimation (EHA). METHODS 8 males performed heat stress tests (HST) (45 min of cycling at 50% of VO2max in 40 °C, 40% RH) before and after heat acclimation sessions. Acclimation sessions were either three consecutive bouts of HWI (40 min of submersion at 40 °C) or EHA (40 min of cycling at 50% VO2max in 40 °C, 40% RH). RESULTS Average change in tympanic temperature (TTympanic) was significantly higher following HWI (2.1 °C ± 0.4) compared to EHA (1.5 °C ± 0.4) (P < 0.05). Decreases in peak heart rate (HR) (HWI: -10 bpm ± 8; EHA: -6 ± 7), average HR (-7 bpm ± 6; -3 ± 4), and average core temperature (-0.4 °C ± 0.3; -0.2 ± 0.4) were evident following acclimation (P < 0.05), but not different between interventions (P > 0.05). Peak rate of perceived exertion (RPEPeak) decreased for HWI and EHA (P < 0.05). Peak thermal sensation (TSPeak) decreased following HWI (P < 0.05) but was not different between interventions (P > 0.05). Plasma volume increased in both intervention groups (HWI: 5.9% ± 5.1; EHA: 5.4% ± 3.7) but was not statistically different (P > 0.05). CONCLUSION HWI induced significantly greater thermal strain compared to EHA at equivalent temperatures during time-matched exposures. However, the greater degree of thermal strain did not result in between intervention differences for cardiovascular, thermoregulatory, or perceptual variables. Findings suggest three HWI sessions may be a potential means to lower HR, TCore, and perceptual strain during exercise in the heat.
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3.
Pre-Exercise Glucose Ingestion May Improve Endurance Capacity in East Asian Student Athletes with Lower Blood Glucose Response.
Koma, R, Terasawa, N
Journal of nutritional science and vitaminology. 2020;(2):150-157
Abstract
The main purpose of this study was to investigate the influence of pre-exercise glucose ingestion after a 2.5-h fast on the endurance capacity and blood glucose response in East Asian athletes who is expected to have genetically low insulin response. A total of 8 Japanese student athletes ingested 1.5 g/kg body mass of glucose (G trial) or 0.5 g/kg body mass of artificial sweetener dissolved in water (P trial) 30 min before exercise test after consuming a standardized breakfast. The exercise test comprised 40 min cycling exercise at 50% maximal oxygen uptake (VO2max), immediately followed by cycling to exhaustion at 70% VO2max. Before analyzing the data, we grouped the subjects into two groups depending on whether they showed rapid increase in blood glucose at the onset of exercise (increase rate in LOW group is <20% and HIGH group is ≥20%) to evaluate subject's insulin response to glucose feeding. No subjects developed rebound hypoglycemia (<70 mg/dL) in the G trial of both group. Significantly higher blood glucose during exercise was recognized only in the G trial of LOW group. Although no significant difference was observed between the two trials of both group, cycling time to exhaustion in the LOW group tended to increase because of glucose ingestion. These results suggest that pre-exercise ingestion of glucose in East Asian student athletes does not induce rebound hypoglycemia regardless of difference in individual insulin responses. Furthermore, individuals with low insulin responses seem to improve endurance performance with glucose ingestion before exercise.
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4.
Muscle and intestinal damage in triathletes.
Tota, Ł, Piotrowska, A, Pałka, T, Morawska, M, Mikuľáková, W, Mucha, D, Żmuda-Pałka, M, Pilch, W
PloS one. 2019;(1):e0210651
Abstract
The aim of the paper was to assess indicators of muscle and intestinal damage in triathletes. The study involved 15 triathletes whose objective for the season was to start in the XTERRA POLAND 2017 event (1,500-m swimming, 36-km cycling, and 10-km mountain running). Before the 14-week preparatory period, the competitors' body composition was measured, aerobic capacity was tested (graded treadmill test) and blood samples were collected to determine markers showing the level of muscle and intestinal damage. Subsequent tests for body composition were carried out before and after the competition. Blood samples for biochemical indicators were collected the day before the competition, after the completed race, and 24 and 48 hours later. A significant decrease in body mass was observed after completing the race (-3.1±1.5%). The mean maximal oxygen uptake level among the studied athletes equalled 4.9±0.4 L·min-1, 58.8±4.5 mL·kg-1·min-1. The significant increase in concentrations of cortisol, c-reactive protein and myoglobin after the competition, significantly correlated with the significant increase in zonulin concentration (post 1h: r = 0.88, p = 0.007, r = 0,79, p = 0.001, r = 0.78, p = 0.001, and post 12h: r = 0.75, p = 0.01, r = 0.71, p = 0.011, r = 0.83, p = 0.02). No significant changes in the concentration of tumour necrosis factor alpha among the examined competitors were noted at following stages of the study. The results of our research showed that in order to monitor overload in the training of triathletes, useful markers reflecting the degree of muscle and intestinal damage include cortisol, testosterone, testosterone to cortisol ratio, c-reactive protein, myoglobin and zonulin. Changes in muscle cell damage markers strongly correlated with changes in zonulin concentration at particular stages of the study. Thus, one can expect that the concentrations of markers depicting the level of muscle cell damage after an intense and long-lasting effort will significantly influence the level of the intestinal barrier.
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5.
Declines in exercise performance are prevented 24 hours after post-exercise ischemic conditioning in amateur cyclists.
Arriel, RA, de Souza, HLR, da Mota, GR, Marocolo, M
PloS one. 2018;(11):e0207053
Abstract
Brief moments of blood flow occlusion followed by reperfusion may promote enhancements in exercise performance. Thus, this study assessed the 24-h effect of post-exercise ischemic conditioning (PEIC) on exercise performance and physiological variables in trained cyclists. In a randomized, single-blind study, 28 trained cyclists (27.1 ± 1.4 years) performed a maximal incremental cycling test (MICT). The outcome measures were creatine kinase (CK), muscle soreness and perceived recovery status, heart rate, perceived exertion and power output. Immediately after the MICT, the cyclists performed 1 of the following 4 interventions: 2 sessions of 5-min occlusion/5-min reperfusion (PEIC or SHAM, 2 x 5) or 5 sessions of 2-min occlusion/2-min reperfusion (PEIC or SHAM, 5 x 2). The PEIC (50 mm Hg above the systolic blood pressure) or SHAM (20 mm Hg) treatment was applied unilaterally on alternating thighs. At 24 h after the interventions, a second MICT was performed. In all the groups, the CK levels were increased compared with the baseline (p < 0.05) after the 24-h MICT. The PEIC groups (2 x 5 and 5 x 2) felt more tired at 24 h post intervention (p < 0.05). However, both PEIC groups maintained their performance (2 x 5: p = 0.819; 5 x 2: p = 0.790), while the SHAM groups exhibited decreased performance at 24 h post intervention compared to baseline (2 x 5: p = 0.015; 5 x 2: p = 0.045). A decrease in the maximal heart rate (HR) was found only in the SHAM 2 x 5 group (p = 0.015). There were no other significant differences in the heart rate, power output or perceived exertion after 24 h compared with the baseline values for any of the interventions (p > 0.05). In conclusion, PEIC led to maintained exercise performance 24 h post intervention in trained cyclists.
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6.
Effect of sprint cycling and stretch-shortening cycle exercises on the neuromuscular, immune and stress indicators in young men.
Verbickas, V, Baranauskiene, N, Eimantas, N, Kamandulis, S, Rutkauskas, S, Satkunskiene, D, Sadauskas, S, Brazaitis, M, Skurvydas, A
Journal of physiology and pharmacology : an official journal of the Polish Physiological Society. 2017;(1):125-132
Abstract
Selection of optimal physical load is essential for desired adaptation including health benefits. We hypothesized that neuromuscular, immune and stress indicators will be higher after energy demanding sprint interval exercise (SIE) than to mechanically demanding stretch-shortening cycle exercise (SSE). The main aim of this study was to assess and compare the kinetics of blood brain-derived neurotrophic factor (BDNF), norepinephrine (NE) and cortisol (as stress indicators) and proinflammatory (IL-6) and anti-inflammatory (IL-10) cytokines within 24 hours after metabolically demanding SIE and after muscle damage inducing SSE. Twenty healthy physically active young men randomly assigned to two equal groups to complete 12 bouts of 5 s stationary cycling sprints every 3 min (SIE) or 200 drop-jumps with 30 s interval between each jump (SSE), respectively. Quadriceps muscle maximal voluntary contraction torque and voluntary activation and soreness were measured and blood samples collected before and 2 min, 1 hour, 12 hours and 24 hours after the SIE and SSE. The BDNF, cortisol, IL-6 and NE levels increased more at 2 min after SIE than SSE (P < 0.05); however, the IL-10 level did not differ between SIE and SSE. BDNF and cortisol levels were decreased at 24 h after both SIE and especially after SSE. The higher was the initial BDNF level, the greater was its decrease at 24 h after both type of exercise. Before exercise BDNF level correlated closely with the change in central fatigue (decrease in voluntary activation) after both SIE and SSE. We thus conclude that both metabolically demanding SIE and muscle damage inflicting SSE induced long-lasting decrease in circulating BDNF which may not promote brain health. The level of circulating BDNF, but not cortisol, IL-6, IL-10 or NE, was associated with changes in central motor fatigue.
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7.
Assessment of pN-GAL as a marker of renal function in elite cyclists during professional competitions.
Andreazzoli, A, Fossati, C, Spaccamiglio, A, Salvo, R, Quaranta, F, Minganti, C, Di Luigi, L, Borrione, P
Journal of biological regulators and homeostatic agents. 2017;(3):829-835
Abstract
Glomerular filtration rate (GFR) has been shown to be lower than physiological values during exercise with a strong negative correlation with exercise intensity. Among new markers of renal function, neutrophil gelatinase-associated lipocalin (NGAL) seems to be very promising. It is an early, sensitive and specific marker of acute kidney injury (AKI) with two isoforms: plasma NGAL (pNGAL) and urinary NGAL (uNGAL). The aim of the present study was to assess acute variations in NGAL plasma levels after performing high endurance physical exercise in a group of professional cyclists during the two major European professional cycling competitions (Giro D’Italia and Tour de France). Eighteen professional cyclistis were recruited for the study. A blood sample was collected during rest (after 8 hours fasting) and immediately after the competition (mountain stages) in order to assess the effect of very intense exercise on kidney function by measuring the variations of pNGAL. We also assessed plasma levels of creatinine, creatine-kinase (CK), LDH, transaminases and electrolytes. The results showed that Creatinine, CK and electrolytes levels remained almost stable between rest and post-competition. The levels of transaminases and NGAL showed a mild increase between rest and post-competition, with a significant difference between the two values only for transaminases (p=0.005). However, post-competition values of all investigated variables remained within the physiological range. The results of the present study suggest that even if NGAL values mildly rose after competition, no kidney injury occurred in these highly trained athletes during mountain stages of professional competitions. Other studies in literature confirmed that high endurance physical exercise seems not to cause renal injury in elite athletes. This is probably due to adaptive mechanisms of renal function and to the adaptation to physical stress gained with training.
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8.
Effect of Caffeine on Perceived Soreness and Functionality Following an Endurance Cycling Event.
Caldwell, AR, Tucker, MA, Butts, CL, McDermott, BP, Vingren, JL, Kunces, LJ, Lee, EC, Munoz, CX, Williamson, KH, Armstrong, LE, et al
Journal of strength and conditioning research. 2017;(3):638-643
Abstract
Caldwell, AR, Tucker, MA, Butts, CL, McDermott, BP, Vingren, JL, Kunces, LJ, Lee, EC, Munoz, CX, Williamson, KH, Armstrong, LE, and Ganio, MS. Effect of caffeine on perceived soreness and functionality following an endurance cycling event. J Strength Cond Res 31(3): 638-643, 2017-Caffeine can reduce muscle pain during exercise; however, the efficacy of caffeine in improving muscle soreness and recovery from a demanding long-duration exercise bout has not been established. The purpose of this study was to investigate the effects of caffeine intake on ratings of perceived muscle soreness (RPMS) and perceived lower extremity functionality (LEF) following the completion of a 164-km endurance cycling event. Before and after cycling RPMS (1-to-6; 6 = severe soreness) and LEF (0-to-80; 80 = full functionality) were assessed by questionnaires. Subjects ingested 3 mg/kg body mass of caffeine or placebo pills in a randomized, double-blind fashion immediately after the ride and for the next 4 mornings (i.e., ∼800 hours) and 3 afternoons (i.e., ∼1200 hours). Before each ingestion, RPMS and LEF were assessed. Afternoon ratings of LEF were greater with caffeine ingestion the first day postride (65.0 ± 6.1 vs. 72.3 ± 6.7; for placebo and caffeine, respectively; p = 0.04), but at no other time points (p > 0.05). The caffeine group tended to have lower overall RPMS in the afternoon versus placebo (i.e., main effect of group; 1.1 ± 0.2 vs. 0.5 ± 0.2; p = 0.09). Afternoon RPMS for the legs was significantly lower in the caffeine group (main effect of caffeine; 1.3 ± 0.2 vs. 0.5 ± 0.3; p = 0.05). In conclusion, ingesting caffeine improved RPMS for the legs, but not LEF in the days following an endurance cycling event. Athletes may benefit from ingesting caffeine in the days following an arduous exercise bout to relieve feelings of soreness and reduced functionality.
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9.
Intensive training and reduced volume increases muscle FXYD1 expression and phosphorylation at rest and during exercise in athletes.
Thomassen, M, Gunnarsson, TP, Christensen, PM, Pavlovic, D, Shattock, MJ, Bangsbo, J
American journal of physiology. Regulatory, integrative and comparative physiology. 2016;(7):R659-69
Abstract
The present study examined the effect of intensive training in combination with marked reduction in training volume on phospholemman (FXYD1) expression and phosphorylation at rest and during exercise. Eight well-trained cyclists replaced their regular training with speed-endurance training (10-12 × ∼30-s sprints) two or three times per week and aerobic high-intensity training (4-5 × 3-4 min at 90-95% of peak aerobic power output) 1-2 times per week for 7 wk and reduced the training volume by 70%. Muscle biopsies were obtained before and during a repeated high-intensity exercise protocol, and protein expression and phosphorylation were determined by Western blot analysis. Expression of FXYD1 (30%), actin (40%), mammalian target of rapamycin (mTOR) (12%), phospholamban (PLN) (16%), and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) γ/δ (25%) was higher (P < 0.05) than before the training intervention. In addition, after the intervention, nonspecific FXYD1 phosphorylation was higher (P < 0.05) at rest and during exercise, mainly achieved by an increased FXYD1 Ser-68 phosphorylation, compared with before the intervention. CaMKII, Thr-287, and eukaryotic elongation factor 2 Thr-56 phosphorylation at rest and during exercise, overall PKCα/β, Thr-638/641, and mTOR Ser-2448 phosphorylation during repeated intense exercise as well as resting PLN Thr-17 phosphorylation were also higher (P < 0.05) compared with before the intervention period. Thus, a period of high-intensity training with reduced training volume increases expression and phosphorylation levels of FXYD1, which may affect Na(+)/K(+) pump activity and muscle K(+) homeostasis during intense exercise. Furthermore, higher expression of CaMKII and PLN, as well as increased phosphorylation of CaMKII Thr-287 may have improved intracellular Ca(2+) handling.
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10.
The Effect of a Dairy-Based Recovery Beverage on Post-Exercise Appetite and Energy Intake in Active Females.
Brown, MA, Green, BP, James, LJ, Stevenson, EJ, Rumbold, PL
Nutrients. 2016;(6)
Abstract
This study was designed to assess the effect of a dairy-based recovery beverage on post-exercise appetite and energy intake in active females. Thirteen active females completed three trials in a crossover design. Participants completed 60 min of cycling at 65% V̇O2peak, before a 120 min recovery period. On completion of cycling, participants consumed a commercially available dairy-based beverage (DBB), a commercially available carbohydrate beverage (CHO), or a water control (H₂O). Non-esterified fatty acids, glucose, and appetite-related peptides alongside measures of subjective appetite were sampled at baseline and at 30 min intervals during recovery. At 120 min, energy intake was assessed in the laboratory by ad libitum assessment, and in the free-living environment by weighed food record for the remainder of the study day. Energy intake at the ad libitum lunch was lower after DBB compared to H₂O (4.43 ± 0.20, 5.58 ± 0.41 MJ, respectively; p = 0.046; (95% CI: -2.28, -0.20 MJ)), but was not different to CHO (5.21 ± 0.46 MJ), with no difference between trials thereafter. Insulin and GLP-17-36 were higher following DBB compared to H₂O (p = 0.015 and p = 0.001, respectively) but not to CHO (p = 1.00 and p = 0.146, respectively). In addition, glucagon was higher following DBB compared to CHO (p = 0.008) but not to H₂O (p = 0.074). The results demonstrate that where DBB consumption may manifest in accelerated recovery, this may be possible without significantly affecting total energy intake and subsequent appetite-related responses relative to a CHO beverage.