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Organisation of Dietary Control for Nutrition-Training Intervention Involving Periodized Carbohydrate (CHO) Availability and Ketogenic Low CHO High Fat (LCHF) Diet
Abstract
We describe the implementation of a 3-week dietary intervention in elite race walkers at the Australian Institute of Sport, with a focus on the resources and strategies needed to accomplish a complex study of this scale. Interventions involved: traditional guidelines of high carbohydrate (CHO) availability for all training sessions (HCHO); a periodized CHO diet which integrated sessions with low CHO and high CHO availability within the same total CHO intake, and a ketogenic low-CHO high-fat diet (LCHF). 7-day menus and recipes were constructed for a communal eating setting to meet nutritional goals as well as individualized food preferences and special needs. Menus also included nutrition support pre, during and post-exercise. Daily monitoring, via observation and food checklists, showed that energy and macronutrient targets were achieved: diets were matched for energy (~14.8 MJ/d) and protein (~2.1 g.kg/d), and achieved desired differences for fat and CHO: HCHO and PCHO: CHO = 8.5 g/kg/d, 60% energy; fat = 20% of energy; LCHF: 0.5 g/kg/d CHO, fat = 78% energy. There were no differences in micronutrient intakes or density between HCHO and PCHO diets; however, the micronutrient density of LCHF was significantly lower. Daily food costs per athlete were similar for each diet (~AUDS$27 ± 10). Successful implementation and monitoring of dietary interventions in sports nutrition research of the scale of the present study require meticulous planning and the expertise of chefs and sports dietitians. Different approaches to sports nutrition support raise practical challenges around cost, micronutrient density, accommodation of special needs and sustainability.
... More recently, Close et al. [10] re-iterated the need for carefully devised standardisation of dietary intake tailored to the measured outcome. Ideally, a dietary standardisation protocol should, where possible, consider individuals' habitual dietary practices and preferences in advance of an intervention [10,11,12,13]. Such consideration could contribute to greater adherence to the study protocol by research participants [14]. ...
... In literature, dietary standardisation protocols have been proposed in nutrient plus exercise research investigating the effect of carbohydrate periodisation on performance in endurancetrained individuals and elite endurance athletes [11,25,26,27]. Similar to this research, the reported dietary standardisation in literature is based on participants' food preferences and is related to participants' body mass [25,26,27] or lean tissue mass [11,12]. In studies by Marquet et al. [26] and Louis et al. [25], the dietary standardisation protocol introduced the habituation phase before the one-week intervention and participants were given precise dietary guidelines of food allowances to meet daily and per EO recommended carbohydrate intake. ...
... Snacks were provided throughout each day and adherence to the prescribed diet was checked daily. As intended, there was no difference between daily energy (kJ·kg -1 ·d -1 ) and protein (g·kg -1 ·d -1 ) intake between groups; for further details refer to Mirtschin et al. [12], who reported the dietary standardisation protocol implemented in the research study by Burke et al. [11]. ...
... During the training camps, held over a~4 week duration, athletes were accommodated at the residential facilities at the AIS to allow all training to be supervised and to permit strict dietary control for the various study interventions [45]. Participants had been undertaking base phase endurance training prior to the training camp, and the weekly training program (typically, 90-140 km/week) represented an intensified training block prior to early season competition. ...
... During the training camps, held over a ~4 week duration, athletes were accommodated at the residential facilities at the AIS to allow all training to be supervised and to permit strict dietary control for the various study interventions [45]. Participants had been undertaking base phase endurance training prior to the training camp, and the weekly training program (typically, 90-140 km/week) represented an intensified training block prior to early season competition. ...
... Dietary treatments provided in this project were implemented using methods previously described elsewhere in detail [45]. Briefly, all foods and fluids consumed during the study were prescribed and provided by a team of chefs, food service dietitian and sports dietitians. ...
Given the importance of exercise economy to endurance performance, we implemented two strategies purported to reduce the oxygen cost of exercise within a 4 week training camp in 21 elite male race walkers. Fourteen athletes undertook a crossover investigation with beetroot juice (BRJ) or placebo (PLA) [2 d preload, 2 h pre-exercise + 35 min during exercise] during a 26 km race walking at speeds simulating competitive events. Separately, 19 athletes undertook a parallel group investigation of a multi-pronged strategy (MAX; n = 9) involving chronic (2 w high carbohydrate [CHO] diet + gut training) and acute (CHO loading + 90 g/h CHO during exercise) strategies to promote endogenous and exogenous CHO availability, compared with strategies reflecting lower ranges of current guidelines (CON; n = 10). There were no differences between BRJ and PLA trials for rates of CHO (p = 0.203) or fat (p = 0.818) oxidation or oxygen consumption (p = 0.090). Compared with CON, MAX was associated with higher rates of CHO oxidation during exercise, with increased exogenous CHO use (CON; peak = ~0.45 g/min; MAX: peak = ~1.45 g/min, p < 0.001). High rates of exogenous CHO use were achieved prior to gut training, without further improvement, suggesting that elite athletes already optimise intestinal CHO absorption via habitual practices. No differences in exercise economy were detected despite small differences in substrate use. Future studies should investigate the impact of these strategies on sub-elite athletes’ economy as well as the performance effects in elite groups.
... Menus deliberately maximised the inclusion of unprocessed/nutrient-rich foods within the strict macronutrient specifications of the LCHF and were consumed by participants under rigorous control. Full details of this methodology and dietary plans are available [23], including analysis that micronutrient content of diet typically met dietary reference intakes, although it was lower than that of the higher CHO diets due to fundamental restrictions on intake of many nutrient-rich foods [23] The methodology around construction and implementation of diets [23] should be repeated in the replication study. ...
... Menus deliberately maximised the inclusion of unprocessed/nutrient-rich foods within the strict macronutrient specifications of the LCHF and were consumed by participants under rigorous control. Full details of this methodology and dietary plans are available [23], including analysis that micronutrient content of diet typically met dietary reference intakes, although it was lower than that of the higher CHO diets due to fundamental restrictions on intake of many nutrient-rich foods [23] The methodology around construction and implementation of diets [23] should be repeated in the replication study. ...
... Menus deliberately maximised the inclusion of unprocessed/nutrient-rich foods within the strict macronutrient specifications of the LCHF and were consumed by participants under rigorous control. Full details of this methodology and dietary plans are available [23], including analysis that micronutrient content of diet typically met dietary reference intakes, although it was lower than that of the higher CHO diets due to fundamental restrictions on intake of many nutrient-rich foods [23] The methodology around construction and implementation of diets [23] should be repeated in the replication study. ...
Introduction:
We repeated our study of intensified training on a ketogenic low-carbohydrate (CHO), high-fat diet (LCHF) in world-class endurance athletes, with further investigation of a "carryover" effect on performance after restoring CHO availability in comparison to high or periodised CHO diets.
Methods:
After Baseline testing (10,000 m IAAF-sanctioned race, aerobic capacity and submaximal walking economy) elite male and female race walkers undertook 25 d supervised training and repeat testing (Adapt) on energy-matched diets: High CHO availability (8.6 g∙kg-1∙d-1 CHO, 2.1 g∙kg-1∙d-1 protein; 1.2 g∙kg-1∙d-1 fat) including CHO before/during/after workouts (HCHO, n = 8): similar macronutrient intake periodised within/between days to manipulate low and high CHO availability at various workouts (PCHO, n = 8); and LCHF (<50 g∙d-1 CHO; 78% energy as fat; 2.1 g∙kg-1∙d-1 protein; n = 10). After Adapt, all athletes resumed HCHO for 2.5 wk before a cohort (n = 19) completed a 20 km race.
Results:
All groups increased VO2peak (ml∙kg-1∙min-1) at Adapt (p = 0.02, 95%CI: [0.35-2.74]). LCHF markedly increased whole-body fat oxidation (from 0.6 g∙min-1 to 1.3 g∙min-1), but also the oxygen cost of walking at race-relevant velocities. Differences in 10,000 m performance were clear and meaningful: HCHO improved by 4.8% or 134 s (95% CI: [207 to 62 s]; p < 0.001), with a trend for a faster time (2.2%, 61 s [-18 to +144 s]; p = 0.09) in PCHO. LCHF were slower by 2.3%, -86 s ([-18 to -144 s]; p < 0.001), with no evidence of superior "rebound" performance over 20 km after 2.5 wk of HCHO restoration and taper.
Conclusion:
Our previous findings of impaired exercise economy and performance of sustained high-intensity race walking following keto-adaptation in elite competitors were repeated. Furthermore, there was no detectable benefit from undertaking an LCHF intervention as a periodised strategy before a 2.5-wk race preparation/taper with high CHO availability.
Trial registration:
Australia New Zealand Clinical Trial Registry: ACTRN12619000794101.
... The "Supernova 1" study investigated parameters around endurance capacity in a cohort of elite endurance race walkers who followed one of the three popular dietary approaches during a three-week period of intensified training: a ketogenic Low Carbohydrate High Fat diet (LCHF), or a diet high in carbohydrates consumed either ad libitum (HCHO) or at specific periods on a daily/weekly basis (PCHO). While the HCHO diet is focused on optimal muscle and brain carbohydrate (CHO) stores for each training session, the PCHO diet involves a strategic combination of sessions with such dietary support as well as other which are undertaken with low muscle glycogen availability to promote greater metabolic stress and cellular adaptation [7,8]. Finally, the LCHF diet involves severe CHO restriction to promote adaptations that increase muscle capacity for fat oxidation [7,8]. ...
... While the HCHO diet is focused on optimal muscle and brain carbohydrate (CHO) stores for each training session, the PCHO diet involves a strategic combination of sessions with such dietary support as well as other which are undertaken with low muscle glycogen availability to promote greater metabolic stress and cellular adaptation [7,8]. Finally, the LCHF diet involves severe CHO restriction to promote adaptations that increase muscle capacity for fat oxidation [7,8]. Details on the rationale for these radically different types of nutrition [6,8] and the actual protocols employed in this study can be found elsewhere [6,7]. ...
... Finally, the LCHF diet involves severe CHO restriction to promote adaptations that increase muscle capacity for fat oxidation [7,8]. Details on the rationale for these radically different types of nutrition [6,8] and the actual protocols employed in this study can be found elsewhere [6,7]. In summary, the Supernova 1 study found that each group of athletes achieved a significant improvement in their aerobic capacity over the training block, which was undertaken during the base phase of the annual training plan. ...
Although the oral microbiota is known to play a crucial role in human health, there are few studies of diet x oral microbiota interactions, and none in elite athletes who may manipulate their intakes of macronutrients to achieve different metabolic adaptations in pursuit of optimal endurance performance. The aim of this study was to investigate the shifts in the oral microbiome of elite male endurance race walkers from Europe, Asia, the Americas and Australia, in response to one of three dietary patterns often used by athletes during a period of intensified training: a High Carbohydrate (HCHO; n = 9; with 60% energy intake from carbohydrates; ~8.5 g kg−1 day−1 carbohydrate, ~2.1 g kg−1 day−1 protein, 1.2 g kg−1 day−1 fat) diet, a Periodised Carbohydrate (PCHO; n = 10; same macronutrient composition as HCHO, but the intake of carbohydrates is different across the day and throughout the week to support training sessions with high or low carbohydrate availability) diet or a ketogenic Low Carbohydrate High Fat (LCHF; n = 10; 0.5 g kg−1 day−1 carbohydrate; 78% energy as fat; 2.1 g kg−1 day−1 protein) diet. Saliva samples were collected both before (Baseline; BL) and after the three-week period (Post treatment; PT) and the oral microbiota profiles for each athlete were produced by 16S rRNA gene amplicon sequencing. Principal coordinates analysis of the oral microbiota profiles based on the weighted UniFrac distance measure did not reveal any specific clustering with respect to diet or athlete ethnic origin, either at baseline (BL) or following the diet-training period. However, discriminant analyses of the oral microbiota profiles by Linear Discriminant Analysis (LDA) Effect Size (LEfSe) and sparse Partial Least Squares Discriminant Analysis (sPLS-DA) did reveal changes in the relative abundance of specific bacterial taxa, and, particularly, when comparing the microbiota profiles following consumption of the carbohydrate-based diets with the LCHF diet. These analyses showed that following consumption of the LCHF diet the relative abundances of Haemophilus, Neisseria and Prevotella spp. were decreased, and the relative abundance of Streptococcus spp. was increased. Such findings suggest that diet, and, in particular, the LCHF diet can induce changes in the oral microbiota of elite endurance walkers.
... Full details of each dietary intervention are presented in Table 2. The methodology used to achieve strict dietary control have been detailed previously (19). ...
... Foods were categorized into heme (red meat, poultry and fish) and non-heme iron sources (breads/cereals/grains, eggs, vegetables, fruits, nuts/seeds and dairy) to determine the contribution of different foods to overall iron intake. Comprehensive breakdown of energy and macronutrients consumed as a part of each diet have been presented in Table 2 and conformed closely to the study goals (19). ...
... All athletes adhered to their allocated diets and the desired differences in dietary fat and CHO consumption were achieved (7,19). Dietary iron intakes are summarized in Table 3. Substantial differences in iron intake between diets were evident (t=-1.92, ...
Purpose:
The short-term restriction of carbohydrate (CHO) can potentially influence iron regulation via modification of post-exercise interleukin-6 (IL-6) and hepcidin levels. This study examined the impact of a chronic ketogenic low CHO-high fat (LCHF) diet on iron status and iron-regulatory markers in elite athletes.
Methods:
International-level race walkers (n=50) were allocated to one of three dietary interventions; i) a high CHO diet (HCHO; n=16), ii) periodized CHO availability (PCHO; n=17) or iii) a LCHF diet (n=17) while completing a periodized training program for 3 weeks. A 19-25 km race walking test protocol was completed at baseline and following adaptation, and changes in serum ferritin, IL-6 and hepcidin concentrations were measured. Results from HCHO and PCHO were combined into one group (CHO; n=33) for analysis.
Results:
The decrease in serum ferritin across the intervention period was substantially greater in the CHO group (37%) compared to the LCHF (23%) group (p=0.021). After dietary intervention, the post-exercise increase in IL-6 was greater in LCHF (13.6-fold increase; 95% CI 7.1-21.4), than athletes adhering to a CHO-rich diet (7.6-fold increase; 5.5-10.2; p=0.033). While no significant differences occurred between diets, confidence intervals indicate 3 h post-exercise hepcidin concentrations were lower after dietary intervention compared to baseline in CHO (β=-4.3; -6.6, -2.0), with no differences evident in LCHF.
Conclusion:
Athletes who adhered to a CHO-rich diet experienced favorable changes to the post-exercise IL-6 and hepcidin response, relative to the LCHF group. Lower serum ferritin after 3 weeks of additional dietary CHO might reflect a larger more adaptive hematological response to training.
... There is now a growing body of evidence demonstrating that LCHF diets impair the performance of endurance exercise at high relative and absolute intensities (13), with at least part of the mechanism being an increase in the oxygen cost of exercise at the same absolute speed (9,12,13,20). In contrast, it has been suggested that ketone bodies may provide a greater Gibbs free energy (ΔG) for ATP production (21) and may therefore be a more efficient metabolic fuel source. ...
... Dietary interventions, as described previously (8,20), were used for baseline and/or adaptation periods. Both dietary treatments were designed to provide adequate energy availability, with a provision of 56 kcal (225 kJ)·kg −1 BM to account for planned training. ...
Consumption of a ketogenic low-carbohydrate (CHO), high-fat (LCHF) diet increases skeletal muscle fat utilization but impairs exercise economy. Whether the concomitant increase in circulating endogenous ketone bodies (KB) alters the capacity to metabolize exogenous ketone supplements such as the popular ketone monoester (KE) is unknown.
Purpose: To determine if LCHF and KE supplementation can synergistically alter exercise metabolism and improve performance.
Methods: Elite race walkers (n=18, 15 male, 3 female; V[Combining Dot Above]O2peak 62 ± 6 mL·min·kg) undertook a 4-stage exercise economy test and real-life 10,000 m race prior to and following a 5-d isoenergetic high CHO (HCHO; ~60-65% CHO, 20% fat; n=9) or LCHF (75-80% fat, <50 g/day CHO, n=9) diet. The LCHF group performed additional economy tests pre/post diet after supplementation with 573 mg·kg body mass KE (HVMN, HVMN Inc.), which was also consumed for Race 2.
Results: The oxygen cost of exercise (relative V[Combining Dot Above]O2, mL·min·kg) increased across all 4 stages following LCHF (p<0.005). This occurred in association with increased fat oxidation rates, with a reciprocal decrease in CHO oxidation (p<0.001). Substrate utilisation in the HCHO group remained unaltered. Consumption of KE prior to the LCHF diet increased circulating KB (p<0.05), peaking at 3.2 ± 0.6 mM but did not alter V[Combining Dot Above]O2 or RER. LCHF diet elevated resting circulating KB (0.3 ± 0.1 vs. 0.1 ± 0.1 mM), but concentrations following supplementation did not differ from the earlier ketone trial. Critically, race performance was impaired by ~6% (p<0.0001) relative to baseline in the LCHF group but was unaltered in HCHO.
Conclusion: Despite elevating endogenous KB production, a LCHF diet does not augment the metabolic responses to KE supplementation, and negatively impacts race performance.
... Participants completed a 3.5-week block of intensified training and laboratory and field testing, supported by either a high-CHO (HCHO) or an isoenergetic LCHF diet (Figure 1, Table 1), consumed under strict dietary control (18). Upon completion of the 3.5-week dietary intervention, a subset of participants (n = 18) completed a further testing block under conditions of acute high CHO availability. ...
... Details of dietary control are described briefly here; more details are described in prior work (18). Participants were allocated into HCHO and LCHF groups based on preference. ...
Objectives: To investigate diet-exercise interactions related to bone markers in elite endurance athletes after a 3.5-week ketogenic low-carbohydrate, high-fat (LCHF) diet and subsequent restoration of carbohydrate (CHO) feeding. Methods: World-class race walkers (25 male, 5 female) completed 3.5-weeks of energy-matched (220 kJ·kg·d−1) high CHO (HCHO; 8.6 g·kg·d−1 CHO, 2.1 g·kg·d−1 protein, 1.2 g·kg·d−1 fat) or LCHF (0.5 g·kg·d−1 CHO, 2.1 g·kg·d−1 protein, 75–80% of energy from fat) diet followed by acute CHO restoration. Serum markers of bone breakdown (cross-linked C-terminal telopeptide of type I collagen, CTX), formation (procollagen 1 N-terminal propeptide, P1NP) and metabolism (osteocalcin, OC) were assessed at rest (fasting and 2 h post meal) and after exercise (0 and 3 h) at Baseline, after the 3.5-week intervention (Adaptation) and after acute CHO feeding (Restoration). Results: After Adaptation, LCHF increased fasting CTX concentrations above Baseline (p = 0.007, Cohen's d = 0.69), while P1NP (p < 0.001, d = 0.99) and OC (p < 0.001, d = 1.39) levels decreased. Post-exercise, LCHF increased CTX concentrations above Baseline (p = 0.001, d = 1.67) and above HCHO (p < 0.001, d = 0.62), while P1NP (p < 0.001, d = 0.85) and OC concentrations decreased (p < 0.001, d = 0.99) during exercise. Exercise-related area under curve (AUC) for CTX was increased by LCHF after Adaptation (p = 0.001, d = 1.52), with decreases in P1NP (p < 0.001, d = 1.27) and OC (p < 0.001, d = 2.0). CHO restoration recovered post-exercise CTX and CTX exercise-related AUC, while concentrations and exercise-related AUC for P1NP and OC remained suppressed for LCHF (p = 1.000 compared to Adaptation). Conclusion: Markers of bone modeling/remodeling were impaired after short-term LCHF diet, and only a marker of resorption recovered after acute CHO restoration. Long-term studies of the effects of LCHF on bone health are warranted.
... A high CHO diet has been traditionally promoted for athletes in order to maximize muscle and liver glycogen stores, as well as the ability to maintain their effective utilization, which often determines the final effectiveness of physical exercise [4]. However, over the last two decades, reports suggesting benefits from purposely and strategically reducing the availability of CHO during some or all of an athlete's training sessions (e.g., low CHO high fat diet, high/low CHO periodization, fed/fasted training) has appeared with increased frequency in the literature [5][6][7][8]. These dietary regimes are supposed to optimize fuel mobilization and utilization during exercise by activating fatty acids as an energy source during exercise. ...
... Following5 -min warm-up on the cycloergometer (Kettler-X1, Kettler, Ense-Parsit, Germany) followed by~5 min rest and preparation for exercise testing, the ICT began at a workload of 75 W for females and 100 W for males at 70 ± 5 rpm (Fig. 1). Every 1.5 min, the workload increased by 25 W until reaching maximum perceived exhaustion, assessed using the Borg scale (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) [57,58]. The respiration indices were recorded with a calibrated ergospirometer (Quark CPET, Cosmed, Rome, Italy) and analyzed with Cosmed CPET software (ver. ...
Background
The ketogenic diet is becoming a popular nutritional model among athletes. However, the relationship between its use and metabolism during exercise seems to have not been fully investigated.
Methods
The aim of the study was to assess the effects of a four-week ketogenic diet (KD) on fat and carbohydrate (CHO) utilization during an incremental cycling test (ICT) in CrossFit-trained female (n = 11) and male (n = 11) athletes. During the ICT (while consuming the customary diet and after the KD), oxygen uptake and carbon dioxide exhalation were registered, and CHO and fat utilization as well as energy expenditure were calculated.
Results
In males, the KD led to an increase in fat utilization (g·min− 1·kgFFM− 1 and % oxidation). It was particularly noticeable at exercise intensities up to 80% of VO2max. An increase in the area under the curve (AUC) was seen in males but not in females at up to ≤65% VO2max of fat utilization.
Conclusions
Male CrossFit-trained athletes seem to be more prone to shifts in macronutrient utilization (in favor of fat utilization) during submaximal intensity exercise under a ketogenic diet than are female athletes.
... • Restricted food variety with K-LCHF diet (e.g., avoidance of grains and most fruit, limited intake of dairy, seeds, vegetables, and nuts) reduces dietary nutrient density compared with higher CHO diets (Mirtschin et al., 2018). ...
... Therefore, we propose the following table of definitions and explanations as a starting point for a more unified dialogue (Tables 1-3), and we encourage our colleagues in this area of research and practice to provide as much objective detail as possible about the dietary strategies with which they experiment and apply in the field with athletes. Indeed, this issue contains a methods paper with a lengthy explanation of the principles, practices, and outcomes of organizing a tightly controlled diettraining intervention of this type (Mirtschin et al., 2018). We note that our efforts typically describe the philosophy of different approaches rather than a single/definitive macronutrient prescription. ...
From the breakthrough studies of dietary carbohydrate and exercise capacity in the 1960s through to the more recent studies of cellular signaling and the adaptive response to exercise in muscle, it has become apparent that manipulations of dietary fat and carbohydrate within training phases, or in the immediate preparation for competition, can profoundly alter the availability and utilization of these major fuels and, subsequently, the performance of endurance sport (events >30 min up to ∼24 hr). A variety of terms have emerged to describe new or nuanced versions of such exercise-diet strategies (e.g., train low, train high, low-carbohydrate high-fat diet, periodized carbohydrate diet). However, the nonuniform meanings of these terms have caused confusion and miscommunication, both in the popular press and among the scientific community. Sports scientists will continue to hold different views on optimal protocols of fuel support for training and competition in different endurance events. However, to promote collaboration and shared discussions, a commonly accepted and consistent terminology will help to strengthen hypotheses and experimental/experiential data around various strategies. We propose a series of definitions and explanations as a starting point for a more unified dialogue around acute and chronic manipulations of fat and carbohydrate in the athlete's diet, noting philosophies of approaches rather than a single/definitive macronutrient prescription. We also summarize some of the key questions that need to be tackled to help produce greater insight into this exciting area of sports nutrition research and practice.
... A dietitian's or nutritionist's expert knowledge on food composition is required to translate nutrition prescriptions into food choices and choice of meal times (Mirtschin et al., 2018). In addition, other factors that influence food choices amongst athletes should also be considered such as taste, convenience, nutrition knowledge and beliefs (Birkenhead and Slater, 2015). ...
Background: It is considered that the implementation of nutrition care process (NCP) leads to more efficient and effective care, as well as enhancing the roles of dietetics and nutrition professionals in the clinical setting. However, little is known about the NCP being implemented in the sports nutrition setting to deliver nutrition care, especially in meal planning. Therefore, this study aims to identify the process that sports nutritionists (SNs) practice in meal planning to plan meals for athletes and identify the application of NCP. Methods: In-depth interviews, using semi-structured interview questions, were conducted with SNs employed at the National Sports Institute of Malaysia. Five SNs who managed different types of sports were recruited. The interviews were audio-recorded and transcribed verbatim. Data were entered into ATLAS.ti 8 and analysed using thematic analysis. Results: The following processes were identified: (i) collecting pertinent data, (ii) analysing the collected data, (iii) determining nutrition prescriptions, (iv) formulating goals and determining actions, (v) implementing actions and recommendations and (vi) monitoring. Conclusions: This study identified six general processes practiced by SNs in meal planning that comprised the NCP's interrelated steps, except nutrition diagnosis statement from the nutrition diagnosis step of the NCP. A comprehensive process and workflow can help sports dietitians or nutritionists to develop individualised meal plans that can improve athletes' nutritional status, adherence, health and sports performance. Abstract Original Article
... A dietitian's or nutritionist's expert knowledge on food composition is required to translate nutrition prescriptions into food choices and choice of meal times (Mirtschin et al., 2018). In addition, other factors that influence food choices amongst athletes should also be considered such as taste, convenience, nutrition knowledge and beliefs (Birkenhead and Slater, 2015). ...
... Indeed, there was a trend to (an unintended) lower energy intake in the CON group which may have reflected the eating behaviour of these individuals. Future studies could focus on a tighter energy match to elucidate the effect of differences in CHO availability, although the effort to achieve such dietary control is noted [69]. For the moment, our study failed to detect performance benefits of training and racing with very high versus high CHO availability, suggesting that CHO intakes reflecting the lower range of the current sports nutrition guidelines are adequate. ...
We implemented a multi-pronged strategy (MAX) involving chronic (2 weeks high carbohydrate [CHO] diet + gut-training) and acute (CHO loading + 90 g·h −1 CHO during exercise) strategies to promote endogenous and exogenous CHO availability, compared with strategies reflecting lower ranges of current guidelines (CON) in two groups of athletes. Nineteen elite male race walkers (MAX: 9; CON:10) undertook a 26 km race-walking session before and after the respective interventions to investigate gastrointestinal function (absorption capacity), integrity (epithelial injury), and symptoms (GIS). We observed considerable individual variability in responses, resulting in a statistically significant (p < 0.001) yet likely clinically insignificant increase (∆ 736 pg·mL −1) in I-FABP after exercise across all trials, with no significant differences in breath H 2 across exercise (p = 0.970). MAX was associated with increased GIS in the second half of the exercise, especially in upper GIS (p < 0.01). Eighteen highly trained male and female distance runners (MAX: 10; CON: 8) then completed a 35 km run (28 km steady-state + 7 km time-trial) supported by either a slightly modified MAX or CON strategy. Inter-individual variability was observed, without major differences in epithelial cell intestinal fatty acid binding protein (I-FABP) or GIS, due to exercise, trial, or group, despite the 3-fold increase in exercise CHO intake in MAX post-intervention. The tight-junction (claudin-3) response decreased in both groups from pre-to post-intervention. Groups achieved a similar performance improvement from pre-to post-intervention (CON = 39 s [95 CI 15-63 s]; MAX = 36 s [13-59 s]; p = 0.002). Although this suggests that further increases in CHO availability above current guidelines do not confer additional advantages, limitations in our study execution (e.g., confounding loss of BM in several individuals despite a live-in training camp environment and significant increases in aerobic capacity due to intensified training) may have masked small differences. Therefore, athletes should meet the minimum CHO guidelines for training and competition goals, noting that, with practice, increased CHO intake can be tolerated, and may contribute to performance outcomes.
... High-fat, low-carbohydrate dietary interventions are typically challenging to implement within both research and practical contexts, due to the substantial changes required to modify typical dietary intakes, and the expense and limited availability of specific foods [7]. Recently, there has been an increased prevalence in the use of smartphone applications, which can assist with dietary prescription and monitoring nutritional intake [8,9]. ...
Periodized carbohydrate availability can enhance exercise capacity, but the effects of short-term fat adaptation carbohydrate restoration (FACR) diets on metabolic responses and exercise performance in endurance athletes have not been conclusively determined. This study aimed to investigate the effect of a FACR diet on measures of resting metabolism, exercise metabolism, and exercise performance. Well-trained male runners (n = 8) completed a FACR dietary intervention (five days’ carbohydrate < 20% and fat > 60% energy, plus one-day carbohydrate ≥ 70% energy), and a control high-carbohydrate (HCHO) diet for six days (carbohydrate > 60% energy; fat < 20% energy) in a randomized crossover design. Pre- and post-intervention metabolic measures included resting metabolic rate (RMR), respiratory quotient (RQ), maximum fat oxidation rate during exercise (MFO), and maximum fat oxidation intensity (FATmax). Measures of exercise performance included maximal oxygen uptake (VO2max), running economy (RE), and 5 km running time trial (5 km-TT). In FACR compared with HCHO, there were significant improvements in FATmax (p = 0.006) and RE (p = 0.048). There were no significant differences (p > 0.05) between FACR and HCHO in RMR, RQ, VO2max, or 5 km-TT. Findings suggest that a short-term (six days) FACR diet may facilitate increased fat oxidation and submaximal exercise economy but does not improve 5 km-TT performance.
... An expert's knowledge of food composition, usually by a dietitian or a nutritionist, is needed to translate nutrition prescription into food choice and 269 | P a g e www.ijacsa.thesai.org mealtime [11]. In the sports setting, the number of experts (sports dietitians or nutritionists) are small, and the demand for creating meal planning for a huge number of athletes often cannot be met. ...
—Individualized meal planning is a nutrition counseling strategy that focuses on improving food behavior changes. In the sports setting, the number of experts who are sports dietitians or nutritionists (SD/SN) is small in number, and yet the demand for creating meal planning for a vast number of athletes often cannot be met. Although some food recommender system had been proposed to provide healthy menu planning for the general population, no similar solution focused on the athlete's needs. In this study, the iDietScoreTM architecture was proposed to give athletes and active individuals virtual individualized meal planning based on their profile, includes energy and macronutrients requirement, sports category, age group, training cycles, training time and individual food preferences. Knowledge acquisition on the expert domain (the SN) was conducted prior to the system design through a semi-structured interview to understand meal planning activities' workflow. The architecture comprises: (1) iDietScoreTM web for SN/SD, (2) mobile application for athletes and active individuals and (3) expert system. SN/SD used the iDietScoreTM web to develop a meal plan and initiate the compilation meal plan database for further use in the expert system. The user used iDietScoreTM mobile app to receive the virtual individualized meal plan. An inference-based expert system was applied in the current study to generate the meal plan recommendation and meal reconstruction for the user. Further research is necessary to evaluate the prototype's usability by the target user (athletes and active individuals). © 2020 Science and Information Organization. All rights reserved.
... A study by Ducrot et al. (2017) found that meal planning is one of the dietary interventions associated with adherence to nutrition guidelines and the consumption of a variety of food groups (9). A dietitian's or nutritionist's expert knowledge on food composition is required to translate nutrition prescriptions into food choices and choice of meal times (10). In addition, other factors that in uence food choices among athletes should also be considered such as taste, convenience, nutrition knowledge and beliefs (11). ...
Background: It is considered that the implementation of nutrition care process (NCP) leads to more efficient and effective care, as well as enhancing the roles of dietetics and nutrition professionals in the clinical setting. However, little is known about the NCP being implemented in the sports nutrition setting to deliver nutrition care, especially in meal planning. Therefore, this study aims to identify the process that sports nutritionists (SNs) practise in meal planning to plan meals for athletes and identify the application of NCP.
Methods: In-depth interviews, using semi-structured interview questions, were conducted with SNs employed at the National Sports Institute of Malaysia. Five SNs who managed different types of sports were recruited. The interviews were audio-recorded and transcribed verbatim. Data were entered into ATLAS.ti 8 and analyzed using thematic analysis.
Results: The following processes were identified: (i) collecting pertinent data; (ii) analyzing the collected data; (iii) determining nutrition prescriptions; (iv) formulating goals and determining actions; (v) implementing actions and recommendations; and (vi) monitoring.
Conclusions: This study identified 6 general processes practiced by sports nutritionists in meal planning that comprised of the NCP’s interrelated steps, except nutrition diagnosis statement from the Nutrition Diagnosis step of the NCP. A comprehensive process and workflow can help sports dietitians or nutritionists to develop individualized meal plans that can improve athletes’ nutritional status, adherence, health and sports performance.
... A minimum of 3-4 weeks appears necessary for performance [7][8][9]; however, whether ergogenic or ergolytic adaptations occur beyond this timeframe is unknown as studies of this duration either do not examine performance [10,11], fail to rigorously monitor dietary intake and training load [14], or do not employ dietary standardisation prior to performance testing [15]. Therefore, to improve quantifying keto-adaptation in endurance athletes, the following variables should be reported: (1) dietary intake (refer to Mirtschin et al. [31] and Shaw et al. [7] for examples); (2) daily (morning) pre-exercise blood and/or urinary KB concentrations (to confirm dietary adherence); and (3) training load. Thereafter, cardiorespiratory parameters, ratings of perceived exertion (RPE), blood metabolites, and substrate oxidation during metabolic tests and/or performance tests can determine the utility of keto-adaptation and, potentially, timecourse adaptations to KD ingestion. ...
Ketone bodies (KB) provide an alternative energy source and uniquely modulate substrate metabolism during endurance exercise. Nutritional ketosis (blood KBs > 0.5 mM) can be achieved within minutes via exogenous ketone supplementation or days-to-weeks via conforming to a very low-carbohydrate, ketogenic diet (KD). In contrast to short-term (< 2 weeks) KD ingestion, chronic adherence (> 3 weeks) leads to a state of keto-adaptation. However, despite elevating blood KBs to similar concentrations, exogenous ketone supplementation and keto-adaptation are not similar metabolic states as they elicit diverse and distinct effects on substrate availability and metabolism during exercise; meaning that their influence on endurance exercise performance is different. In contrast to contemporary, high(er)-carbohydrate fuelling strategies, inducing nutritional ketosis is rarely ergogenic irrespective of origin and, in fact, can impair endurance performance. Nonetheless, exogenous ketone supplementation and keto-adaptation possess utility for select endurance events and individuals, thus warranting further research into their performance effects and potential strategies for their optimisation. It is critical, however, that future research considers the limitations of measuring blood KB concentrations and their utilisation, and assess the effect of nutritional ketosis on performance using exercise protocols reflective of real-world competition. Furthermore, to reliably assess the effects of keto-adaptation, rigorous dietary-training controls of sufficient duration should be prioritised.
... Further details regarding each dietary intervention employed in the lead-up to this study are reported elsewhere. 11 Following the 3-week adaptation period, athletes completed a race walking protocol on two occasions to determine the iron-regulatory response to exercise (Fig. 1). This protocol included a trial on day 1 (Adapt), performed while athletes were still adhering to (and were therefore adapted to) their allocated dietary intervention. ...
... Further details regarding each dietary intervention employed in the lead-up to this study are reported elsewhere. 11 Following the 3-week adaptation period, athletes completed a race walking protocol on two occasions to determine the iron-regulatory response to exercise (Fig. 1). This protocol included a trial on day 1 (Adapt), performed while athletes were still adhering to (and were therefore adapted to) their allocated dietary intervention. ...
Objectives: Adhering to a low carbohydrate (CHO) high fat (LCHF) diet can alter markers of iron metabolism in endurance athletes. This investigation examined the re-introduction of CHO prior to, and during exercise on the iron-regulatory response to exercise in a homogenous (in regard to serum ferritin concentration) group of athletes adapted to a LCHF diet. Design: Parallel groups design. Methods: Three weeks prior to the exercise trials, twenty-three elite race walkers adhered to either a CHO-rich (n = 14) or LCHF diet (n = 9). A standardised 19–25 km race walk was performed while athletes were still adhering to their allocated dietary intervention (Adapt). A second test was performed three days later, where all athletes were placed on a high CHO diet (CHO Restoration). Venous blood samples were collected pre-, post- and 3 h post-exercise and measured for interleukin-6 (IL-6) and hepcidin-25. Results: The post-exercise IL-6 increase was greater in LCHF (p < 0.001) during both the Adapt (LCHF: 13.1-fold increase; 95% CI: 5.6–23.0, CHO: 8.0-fold increase; 5.1–11.1) and CHO Restoration trials (LCHF: 18.5-fold increase; 10.9–28.9, CHO: 6.3-fold increase; 3.9–9.5); outcomes were not different between trials (p = 0.84). Hepcidin-25 concentrations increased 3 h post-exercise (p < 0.001), however, they did not differ between trials (p = 0.46) or diets (p = 0.84). Conclusions: The elevated IL-6 response in athletes adapted to a LCHF diet was not attenuated by an acute increase in exogenous CHO availability. Despite diet-induced differences in IL-6 response to exercise, post-exercise hepcidin levels were similar between diets and trials, indicating CHO availability has minimal influence on post-exercise iron metabolism.
... −1 . Full details of the specific dietary intervention and training (see Burke et al., in review), and the methodology of achieving this level of dietary control are presented elsewhere (Mirtschin et al., 2018). Before and during the study, athletes completed a daily wellness log to document their perceived wellness and any illness symptoms. ...
Carbohydrate (CHO) availability could alter mucosal immune responses to exercise. This study compared the effect of three dietary approaches to CHO availability on resting and post-exercise s-IgA levels. Elite race walkers (n = 26) adhered to a high CHO diet (HCHO), periodised CHO availability (PCHO) or a low CHO/high fat diet (LCHF) for 3 weeks while completing an intensified training program. HCHO and PCHO groups consumed 8.0–8.5 g.kg⁻¹ CHO daily, with timing of ingestion manipulated to alter CHO availability around key training sessions. The LCHF diet comprised 80% fat and restricted CHO to < 50 g.day⁻¹. A race walk test protocol (19 km females, 25 km males) was completed at baseline, after adaptation, and following CHO restoration. On each occasion, saliva samples were obtained pre- and post-exercise to quantify s-IgA levels. Resting s-IgA secretion rate substantially increased ~ two-fold post-intervention in all groups (HCHO: 2.2 ± 2.2, PCHO: 2.8 ± 3.2, LCHF: 1.6 ± 1.6; fold-change± 95% confidence limits), however, no substantial differences between dietary treatments were evident. Post-exercise, substantial 20–130% increases in s-IgA concentration and 43–64% reductions in flow rate occurred in all dietary treatments, with trivial differences evident between groups. It appears that high volume training overrides any effect of manipulating CHO availability on mucosal immunity in elite athletes.
... Energy and nutrient intake provided by the diets was calculated from a food analysis database specific to Australian foods (Foodworks Version 9, Highgate Hill, Australia) by the same registered dietitian. Full details of the methodology for creating, providing, and recording food intake can be found elsewhere [35]. ...
Although short (up to 3 days) exposure to major shifts in macronutrient intake appears to alter acid-base status, the effects of sustained (>1 week) interventions in elite athletes has not been determined. Using a non-randomized, parallel design, we examined the effect of adaptations to 21 days of a ketogenic low carbohydrate high fat (LCHF) or periodized carbohydrate (PCHO) diet on pre- and post-exercise blood pH, and concentrations of bicarbonate (HCO₃-) and lactate (La-) in comparison to a high carbohydrate (HCHO) control. Twenty-four (17 male and 7 female) elite-level race walkers completed 21 days of either LCHF (n = 9), PCHO (n = 7), or HCHO (n = 8) under controlled diet and training conditions. At baseline and post-intervention, blood pH, blood [HCO₃-], and blood [La-] were measured before and after a graded exercise test. Net endogenous acid production (NEAP) over the previous 48-72 h was also calculated from monitored dietary intake. LCHF was not associated with significant differences in blood pH, [HCO₃-], or [La-], compared with the HCHO diet pre- or post-exercise, despite a significantly higher NEAP (mEq·day-1) (95% CI = [10.44; 36.04]). Our results indicate that chronic dietary interventions are unlikely to influence acid-base status in elite athletes, which may be due to pre-existing training adaptations, such as an enhanced buffering capacity, or the actions of respiratory and renal pathways, which have a greater influence on regulation of acid-base status than nutritional intake.
Dietary restriction of carbohydrate has been demonstrated to be beneficial for nervous system dysfunction in animal models and may be beneficial for human chronic pain. The purpose of this review is to assess the impact of a low-carbohydrate/ketogenic diet on the adult nervous system function and inflammatory biomarkers to inform nutritional research for chronic pain. An electronic data base search was carried out in May 2021. Publications were screened for prospective research with dietary carbohydrate intake <130g/day and duration of ≥2 weeks. Studies were categorised into those reporting adult neurological outcomes to be extracted for analysis and those reporting other adult research outcomes Both groups were screened again for reported inflammatory biomarkers. From 1548 studies there were 847 studies included. Sixty-four reported neurological outcomes with 83% showing improvement. Five hundred and twenty-three studies had a different research focus (metabolic n=394, sport/performance n=51, cancer n=33, general n=30, neurological with non-neuro outcomes n=12, or gastrointestinal n=4). The second screen identified 63 studies reporting on inflammatory biomarkers with 71% reporting a reduction in inflammation. The overall results suggest a favourable outcome on the nervous system and inflammatory biomarkers from a reduction in dietary carbohydrates. Both nervous system sensitisation and inflammation occur in chronic pain and the results from this review indicate it may be improved by low-carbohydrate nutritional therapy. More clinical trials within this population are required to build on the few human trials that have been done.
Key points:
Brief (5-6 d) adaptation to LCHF in elite athletes increased exercise fat oxidation to rates previously observed with medium (3-4 wk) or chronic (>12 month) adherence to this diet, with metabolic changes being washed out in a similar timeframe Increased fat utilisation during exercise was associated with a 5-8% increase in oxygen cost at speeds related to Olympic Program races Acute restoration of endogenous CHO availability (24 h HCHO diet, pre-race CHO) only partially restored substrate utilisation during a race warm-up. Fat oxidation continued to be elevated above Baseline values although it was lower than achieved by 5-6 d keto-adaptation; CHO oxidation only reached 61% and 78% of values previously seen at exercise intensities related to race events. Acute restoration of CHO availability failed to overturn the impairment of high-intensity endurance performance previously associated with LCHF adaptation, potentially due to the blunted capacity for CHO oxidation.
Abstract:
We investigated substrate utilisation during exercise after brief (5-6 d) adaptation to a ketogenic low-carbohydrate (CHO), high-fat (LCHF) and similar washout period. Thirteen world-class male race walkers completed economy testing, 25-km training and a 10,000 m race (Baseline), with high CHO availability (HCHO), repeating this (Adaptation) after 5-6 d LCHF (n = 7; CHO: <50 g d-1 , protein: 2.2 g kg-1 d-1 ; 80% fat) or HCHO (n = 6; CHO: 9.7 g kg-1 d-1 ; protein: 2.2 g kg-1 d-1 ). Adaptation race was undertaken after 24-hr HCHO and pre-race CHO (2 g kg-1 ), identical to Baseline race. Substantial (>200%) increases in exercise fat oxidation occurred in LCHF Adaptation economy and 25-km tests, reaching mean rates of ∼1.43 g min-1 . However, relative VO2 (mL min-1 kg-1 ) was higher (p < 0.0001), by ∼ 8% and 5% at speeds related to 50-km and 20-km events. During Adaptation Race warm-up in LCHF, rates of fat and CHO oxidation at these speeds were decreased and increased respectively (p < 0.001) compared with the previous day, but were not restored to Baseline values. Performance changes differed between groups (p = 0.009), with all HCHO athletes improving in Adaptation Race [5.7 (5.6)%], while 6/7 LCHF athletes were slower [2.2 (3.4)%]. Substrate utilisation returned to Baseline values after 5-6 d of HCHO. In summary, robust changes in exercise substrate use occurred in 5-6 days of extreme changes in CHO intake. However, adaptation to LCHF plus acute restoration of endogenous CHO availability failed to restore high-intensity endurance performance, with CHO oxidation rates remaining blunted. This article is protected by copyright. All rights reserved.
The ability of ketogenic low-carbohydrate (CHO) high-fat (K-LCHF) diets to enhance muscle fat oxidation has led to claims that it is the 'future of elite endurance sport'. There is robust evidence that substantial increases in fat oxidation occur, even in elite athletes, within 3-4 weeks and possibly 5-10 days of adherence to a K-LCHF diet. Retooling of the muscle can double exercise fat use to ∼1.5 g min-1 , with the intensity of maximal rates of oxidation shifting from ∼45% to ∼70% of maximal aerobic capacity. Reciprocal reductions in CHO oxidation during exercise are clear, but current evidence to support the hypothesis of the normalization of muscle glycogen content with longer-term adaptation is weak. Importantly, keto-adaptation may impair the muscle's ability to use glycogen for oxidative fates, compromising the use of a more economical energy source when the oxygen supply becomes limiting and, thus, the performance of higher-intensity exercise (>80% maximal aerobic capacity). Even with moderate intensity exercise, individual responsiveness to K-LCHF is varied, with extremes at both ends of the performance spectrum. Periodisation of K-LCHF with high CHO availability might offer opportunities to restore capacity for higher-intensity exercise, but investigations of various models have failed to find a benefit over dietary approaches based on current sports nutrition guidelines. Endurance athletes who are contemplating the use of K-LCHF should undertake an audit of event characteristics and personal experiences to balance the risk of impaired performance of higher-intensity exercise with the likelihood of an unavoidable depletion of carbohydrate stores.
EDİTÖRLER
Doç. Dr. Elif KARAGÜN
Uzm. Ozan YILMAZ
DİL VE YAZIM EDİTÖRÜ
Arş. Gör. Sümeyra ALAN
Bölüm 1:
Çocuklarda Voleybol Temel Beceri Çalışmalarının Yeri ve Önemi
Doç. Dr. Betül BAYAZIT, Öğr. Gör. Uğur ÇITAK
Bölüm 2:
Öncesi ve Sonrasıyla Londra Olimpiyatları; Sporcuların Psikolojik
Özellikleri ve TOHM Projesi
Doç. Dr. Elif KARAGÜN
Bölüm 3:
Ev Kadınları ve Fiziksel Aktivite
Doç. Dr. Serap ÇOLAK
Bölüm 4:
Kocaeli Üniversitesi Spor Bilimleri Fakültesi Öğrencilerinin Zaman
Yönetimi Becerilerinin Çeşitli Değişkenler Açısından İncelenmesi
Öğr. Gör. Enis ÇOLAK, Doç. Dr. Özgür DİNÇER, Abdullah TURAN
Bölüm 5:
Üniversiteler Arası Halk Oyunları Yarışmasına Katılan Sporcuların
Spor Yaralanması Kaygısı İle Öz Yeterlik Düzeyleri Arasındaki
İlişkinin İncelenmesi
Dr. Öğretim Üyesi Servet REYHAN
Bölüm 6:
Sporda Ketojenik Diyet: Bir Literatür Taraması
Arş. Gör. Müge SARPER KAHVECİ
Bölüm 7:
Sakarya Belediyelerinin Stratejik Planlarının Spor Yönüyle
İncelenmesi
Faik Orhun TAPŞIN, Doç. Dr. Levent ATALI
Background
Price and affordability of foods are important determinants of health. Targeted food pricing policies may help improve population diets. However, methods producing comparable data to inform relevant policy decisions are lacking in Australia and globally. The objective was to develop and pilot standardised methods to assess the price, relative price and affordability of healthy (recommended) and current (unhealthy) diets and test impacts of a potential policy change. Methods
Methods followed the optimal approach proposed by INFORMAS using recent Australian dietary intake data and guidelines. Draft healthy and current (unhealthy) diet baskets were developed for five household structures. Food prices were collected in stores in a high and low SES location in Brisbane, Australia. Diet prices were calculated and compared with household incomes, and with potential changes to the Australian Taxation System. Wilcoxen-signed rank tests were used to compare differences in price. ResultsThe draft tools and protocols were deemed acceptable at household level, but methods could be refined. All households spend more on current (unhealthy) diets than required to purchase healthy (recommended) diets, with the majority (53–64 %) of the food budget being spent on ‘discretionary’ choices, including take-away foods and alcohol. A healthy diet presently costs between 20–31 % of disposable income of low income households, but would become unaffordable for these families under proposed changes to expand the GST to apply to all foods in Australia. Conclusions
Results confirmed that diet pricing methods providing meaningful, comparable data to inform potential fiscal and health policy actions can be developed, but draft tools should be refined. Results suggest that healthy diets can be more affordable than current (unhealthy) diets in Australia, but other factors may be as important as price in determining food choices.
Purpose:
We investigated the effect of a chronic dietary periodization strategy on endurance performance in trained athletes.
Methods:
21 triathletes (V[Combining Dot Above]O2max: 58.7 ± 5.7 mL·min·kg) were divided into 2 groups: a "sleep-low" (SL, n = 11) and a control group (CON, n = 10) consumed the same daily carbohydrate (CHO) intake (6 g·kg·d) but with different timing over the day to manipulate CHO availability before and after training sessions. The "sleep low" strategy consisted of a 3-week training/diet intervention comprising three blocks of diet/exercise manipulations: 1) "train-high" interval training sessions (HIT) in the evening with high-CHO availability; 2) overnight CHO restriction ("sleeping-low"), and 3) "train-low" sessions with low endogenous and exogenous CHO availability. The CON group followed the same training program but with high CHO availability throughout training sessions (no CHO restriction overnight, training sessions with exogenous CHO provision).
Results:
There was a significant improvement in delta efficiency during submaximal cycling for SL versus CON (CON: +1.4 ± 9.3 %, SL: +11 ± 15 %, P<0.05). SL also improved supra-maximal cycling to exhaustion at 150% of peak aerobic power (CON: +1.63 ± 12.4 %, SL: +12.5 ± 19.0 %; P = 0.06) and 10 km running performance (CON: -0.10 ± 2.03 %, SL: -2.9 ± 2.15 %; P < 0.05). Fat mass was decreased in SL (CON: -2.6 ± 7.4; SL: -8.5 ± 7.4 %PRE, P < 0.01), but not lean mass (CON: -0.22 ± 1.0; SL: -0.16 ± 1.7 %PRE).
Conclusion:
Short-term periodization of dietary CHO availability around selected training sessions promoted significant improvements in submaximal cycling economy, as well as supra-maximal cycling capacity and 10 km running time in trained endurance athletes.
During the period 1985-2005, studies examined the proposal that adaptation to a low-carbohydrate (<25 % energy), high-fat (>60 % energy) diet (LCHF) to increase muscle fat utilization during exercise could enhance performance in trained individuals by reducing reliance on muscle glycogen. As little as 5 days of training with LCHF retools the muscle to enhance fat-burning capacity with robust changes that persist despite acute strategies to restore carbohydrate availability (e.g., glycogen supercompensation, carbohydrate intake during exercise). Furthermore, a 2- to 3-week exposure to minimal carbohydrate (<20 g/day) intake achieves adaptation to high blood ketone concentrations. However, the failure to detect clear performance benefits during endurance/ultra-endurance protocols, combined with evidence of impaired performance of high-intensity exercise via a down-regulation of carbohydrate metabolism led this author to dismiss the use of such fat-adaptation strategies by competitive athletes in conventional sports. Recent re-emergence of interest in LCHF diets, coupled with anecdotes of improved performance by sportspeople who follow them, has created a need to re-examine the potential benefits of this eating style. Unfortunately, the absence of new data prevents a different conclusion from being made. Notwithstanding the outcomes of future research, there is a need for better recognition of current sports nutrition guidelines that promote an individualized and periodized approach to fuel availability during training, allowing the athlete to prepare for competition performance with metabolic flexibility and optimal utilization of all muscle substrates. Nevertheless, there may be a few scenarios where LCHF diets are of benefit, or at least are not detrimental, for sports performance.
AimTo determine the cost and affordability of a gluten-free healthy food basket for four reference families in Australia. A secondary aim was to determine the price differential between commonly available gluten-free and gluten-containing food staples.Methods
Exploratory study using an amalgamation of two commonly used food basket costing methods. Two food basket types were constructed for four common Australian family types. These were designated the Healthy Food Basket and modified (gluten-free) Healthy Food Basket. Baskets were priced at five locations and costs as a proportion of the Equivalised Household Disposable Income and average weekly earnings for welfare recipients were calculated. The price differential for four common bread and cereal staples were also calculated per 100 g.ResultsThe gluten-free healthy food basket was significantly more expensive compared to a gluten-containing healthy food basket for all family types. The gluten-free basket was considered unaffordable for three of the four common family types. Gluten-free staples are significantly more expensive than their gluten-containing counterparts.Conclusions
Compliance to a gluten-free diet may be more difficult for some families due to the significant price discrepancy of gluten-free items. Families on welfare with people who require a gluten-free diet are particularly vulnerable to food insecurity. Consideration should be given to the creation of a national subsidised medical foods program to enable equitable access to affordable gluten-free staple foods via prescription.
Abstract Traditional nutritional approaches to endurance training have typically promoted high carbohydrate (CHO) availability before, during and after training sessions to ensure adequate muscle substrate to meet the demands of high daily training intensities and volumes. However, during the past decade, data from our laboratories and others have demonstrated that deliberately training in conditions of reduced CHO availability can promote training-induced adaptations of human skeletal muscle (i.e. increased maximal mitochondrial enzyme activities and/or mitochondrial content, increased rates of lipid oxidation and, in some instances, improved exercise capacity). Such data have led to the concept of 'training low, but competing high' whereby selected training sessions are completed in conditions of reduced CHO availability (so as to promote training adaptation), but CHO reserves are restored immediately prior to an important competition. The augmented training response observed with training-low strategies is likely regulated by enhanced activation of key cell signalling kinases (e.g. AMPK, p38MAPK), transcription factors (e.g. p53, PPARδ) and transcriptional co-activators (e.g. PGC-1α), such that a co-ordinated up-regulation of both the nuclear and mitochondrial genomes occurs. Although the optimal practical strategies to train low are not currently known, consuming additional caffeine, protein, and practising CHO mouth-rinsing before and/or during training may help to rescue the reduced training intensities that typically occur when 'training low', in addition to preventing protein breakdown and maintaining optimal immune function. Finally, athletes should practise 'train-low' workouts in conjunction with sessions undertaken with normal or high CHO availability so that their capacity to oxidise CHO is not blunted on race day.
An important goal of the athlete's everyday diet is to provide the muscle with substrates to fuel the training programme that will achieve optimal adaptation for performance enhancements. In reviewing the scientific literature on post-exercise glycogen storage since 1991, the following guidelines for the training diet are proposed. Athletes should aim to achieve carbohydrate intakes to meet the fuel requirements of their training programme and to optimize restoration of muscle glycogen stores between workouts. General recommendations can be provided, preferably in terms of grams of carbohydrate per kilogram of the athlete's body mass, but should be fine-tuned with individual consideration of total energy needs, specific training needs and feedback from training performance. It is valuable to choose nutrient-rich carbohydrate foods and to add other foods to recovery meals and snacks to provide a good source of protein and other nutrients. These nutrients may assist in other recovery processes and, in the case of protein, may promote additional glycogen recovery when carbohydrate intake is suboptimal or when frequent snacking is not possible. When the period between exercise sessions is
Key points
Three weeks of intensified training and mild energy deficit in elite race walkers increases peak aerobic capacity independent of dietary support.
Adaptation to a ketogenic low carbohydrate, high fat (LCHF) diet markedly increases rates of whole‐body fat oxidation during exercise in race walkers over a range of exercise intensities.
The increased rates of fat oxidation result in reduced economy (increased oxygen demand for a given speed) at velocities that translate to real‐life race performance in elite race walkers.
In contrast to training with diets providing chronic or periodised high carbohydrate availability, adaptation to an LCHF diet impairs performance in elite endurance athletes despite a significant improvement in peak aerobic capacity.
Abstract
We investigated the effects of adaptation to a ketogenic low carbohydrate (CHO), high fat diet (LCHF) during 3 weeks of intensified training on metabolism and performance of world‐class endurance athletes. We controlled three isoenergetic diets in elite race walkers: high CHO availability (g kg⁻¹ day⁻¹: 8.6 CHO, 2.1 protein, 1.2 fat) consumed before, during and after training (HCHO, n = 9); identical macronutrient intake, periodised within or between days to alternate between low and high CHO availability (PCHO, n = 10); LCHF (< 50 g day⁻¹ CHO; 78% energy as fat; 2.1 g kg⁻¹ day⁻¹ protein; LCHF, n = 10). Post‐intervention, V˙O2 peak during race walking increased in all groups (P < 0.001, 90% CI: 2.55, 5.20%). LCHF was associated with markedly increased rates of whole‐body fat oxidation, attaining peak rates of 1.57 ± 0.32 g min⁻¹ during 2 h of walking at ∼80% V˙O2 peak . However, LCHF also increased the oxygen (O2) cost of race walking at velocities relevant to real‐life race performance: O2 uptake (expressed as a percentage of new V˙O2 peak ) at a speed approximating 20 km race pace was reduced in HCHO and PCHO (90% CI: −7.047, −2.55 and −5.18, −0.86, respectively), but was maintained at pre‐intervention levels in LCHF. HCHO and PCHO groups improved times for 10 km race walk: 6.6% (90% CI: 4.1, 9.1%) and 5.3% (3.4, 7.2%), with no improvement (−1.6% (−8.5, 5.3%)) for the LCHF group. In contrast to training with diets providing chronic or periodised high‐CHO availability, and despite a significant improvement in V˙O2 peak , adaptation to the topical LCHF diet negated performance benefits in elite endurance athletes, in part due to reduced exercise economy.
When testing is undertaken to monitor an athlete's progress toward competition goals or the effect of an intervention on athletic outcomes, sport scientists should aim to minimize extraneous variables that influence the reliability, sensitivity, or validity of performance measurement. Dietary preparation is known to influence metabolism and exercise performance. Few studies, however, systematically investigate the outcomes of protocols that acutely control or standardize dietary intake in the hours and days before a performance trial. This review discusses the nutrients and dietary components that should be standardized before performance testing and reviews current approaches to achieving this. The replication of habitual diet or dietary practices, using tools such as food diaries or dietary recalls to aid compliance and monitoring, is a common strategy, and the use of education aids to help athletes achieve dietary targets offers a similarly low burden on the researcher. However, examination of dietary intake from real-life examples of these protocols reveals large variability between and within participants. Providing participants with prepackaged diets reduces this variability but can increase the burden on participants, as well as the researcher. Until studies can better quantify the effect of different protocols of dietary standardization on performance testing, sport scientists can only use a crude cost-benefit analysis to choose the protocols they implement. At the least, study reports should provide a more comprehensive description of the dietary-standardization protocols used in the research and the effect of these on the dietary intake of participants during the period of interest.
Based upon the fact that fatigue during intense prolonged exercise is commonly due to depletion of muscle and liver glycogen which limits both training and competitive performance, this paper has proposed extraordinary dietary practices which generally advocate high carbohydrate intake at all times before, during and after exercise. The simple goal is to have as much carbohydrate in the body as possible during the latter stages of prolonged intense exercise when the ability for intense exercise usually becomes limiting to performance. This theory is put into practice by recommending that carbohydrate intake after exhaustive exercise should average 50 g per 2 h of mostly moderate and high glycaemic carbohydrate foods. The aim should be to ingest a total of about 600 g in 24 h. Carbohydrate intake should not be avoided during the 4 h period before exercise and in fact it is best to eat at least 200 g during this time. When possible, carbohydrate should be ingested during exercise, generally in the form of solutions containing glucose/sucrose/maltodextrins, at a rate of 30-60 g h-1. Emphasis has been placed upon eating the optimal amount and best type of carbohydrate at the proper times because these practices demand a large amount of food. When diet is not carefully planned according to these guidelines, endurance athletes tend to consume too little carbohydrate because they become satiated with high fat in their diet and they go through periods in the day when recovery of glycogen stores is suboptimal and thus precious time is wasted.
To study the effect of chronic ketosis on exercise performance in endurance-trained humans, five well-trained cyclists were fed a eucaloric balanced diet (EBD) for one week providing 35-50 kcal/kg/d, 1.75 g protein/kg/d and the remainder of kilocalories as two-thirds carbohydrate (CHO) and one-third fat. This was followed by four weeks of a eucaloric ketogenic diet (EKD), isocaloric and isonitrogenous with the EBD but providing less than 20 g CHO daily. Both diets were appropriately supplemented to meet the recommended daily allowances for vitamins and minerals. Pedal ergometer testing of maximal oxygen uptake (VO2max) was unchanged between the control week (EBD-1) and week 3 of the ketogenic diet (EKD-3). The mean ergometer endurance time for continuous exercise to exhaustion (ENDUR) at 62%-64% of VO2max was 147 minutes at EBD-1 and 151 minutes at EKD-4. The ENDUR steady-state RQ dropped from 0.83 to 0.72 (P less than 0.01) from EBD-1 to EKD-4. In agreement with this were a three-fold drop in glucose oxidation (from 15.1 to 5.1 mg/kg/min, P less than 0.05) and a four-fold reduction in muscle glycogen use (0.61 to 0.13 mmol/kg/min, P less than 0.01). Neither clinical nor biochemical evidence of hypoglycemia was observed during ENDUR at EKD-4. These results indicate that aerobic endurance exercise by well-trained cyclists was not compromised by four weeks of ketosis. This was accomplished by a dramatic physiologic adaptation that conserved limited carbohydrate stores (both glucose and muscle glycogen) and made fat the predominant muscle substrate at this submaximal power level.
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