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1.
Efficacy of Popular Diets Applied by Endurance Athletes on Sports Performance: Beneficial or Detrimental? A Narrative Review.
Devrim-Lanpir, A, Hill, L, Knechtle, B
Nutrients. 2021;(2)
Abstract
Endurance athletes need a regular and well-detailed nutrition program in order to fill their energy stores before training/racing, to provide nutritional support that will allow them to endure the harsh conditions during training/race, and to provide effective recovery after training/racing. Since exercise-related gastrointestinal symptoms can significantly affect performance, they also need to develop strategies to address these issues. All these factors force endurance athletes to constantly seek a better nutritional strategy. Therefore, several new dietary approaches have gained interest among endurance athletes in recent decades. This review provides a current perspective to five popular diet approaches: (a) vegetarian diets, (b) high-fat diets, (c) intermittent fasting diets, (d) gluten-free diet, and (e) low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diets. We reviewed scientific studies published from 1983 to January 2021 investigating the impact of these popular diets on the endurance performance and health aspects of endurance athletes. We also discuss all the beneficial and harmful aspects of these diets, and offer key suggestions for endurance athletes to consider when following these diets.
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2.
Effects of Intermittent Fasting on Specific Exercise Performance Outcomes: A Systematic Review Including Meta-Analysis.
Correia, JM, Santos, I, Pezarat-Correia, P, Minderico, C, Mendonca, GV
Nutrients. 2020;(5)
Abstract
Intermittent fasting (IF) has been studied in athletes during Ramadan and in those willing to decrease adiposity while maintaining or increasing lean body mass. The purpose of this systematic review was to summarize the effects of IF on performance outcomes. We searched peer-reviewed articles in the following databases: PubMed, Web of Science and Sport Discus (up to December 2019). Studies were selected if they included samples of adults (≥18 years), had an experimental or observational design, investigated IF (Ramadan and time-restricted feeding (TRF)), and included performance outcomes. Meta-analytical procedures were conducted when feasible. Twenty-eight articles met the eligibility criteria. Findings indicated that maximum oxygen uptake is significantly enhanced with TRF protocols (SMD = 1.32, p = 0.001), but reduced with Ramadan intermittent fasting (Ramadan IF; SMD = -2.20, p < 0.001). Additional effects of IF may be observed in body composition (body mass and fat mass). Non-significant effects were observed for muscle strength and anaerobic capacity. While Ramadan IF may lead to impairments in aerobic capacity, TRF may be effective for improving it. As there are few studies per performance outcome, more research is needed to move the field forward.
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3.
Intermittent Fasting and Its Effects on Athletic Performance: A Review.
Levy, E, Chu, T
Current sports medicine reports. 2019;(7):266-269
Abstract
Intermittent fasting (IFast) has been around for most of human history, and its proposed health benefits have been mentioned in ancient civilizations. However, recently, there has been a renewed public interest in IFast. Given the importance of nutrition in optimizing athletic performance, there is a concern about the effects of IFast on athletics. Most of the studies looking at performance and fasting are regarding athletes who observe Ramadan. Looking at high-intensity, endurance, and resistance exercises, studies have been varied but are uniform in showing that there is no benefit to athletic performance while fasting. More long-term studies need to be done to evaluate specific fasting protocols during sport.
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4.
The effect of 10 days of intermittent fasting on Wingate anaerobic power and prolonged high-intensity time-to-exhaustion cycling performance.
Naharudin, MNB, Yusof, A
European journal of sport science. 2018;(5):667-676
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Abstract
Many physically active individuals have undertaken intermittent fasting to reduce their daily caloric intake. However, abstaining from meals for a specific length of time may lead to the acute disturbance of highly carbohydrate-dependent exercise performance. The purpose of this study was to observe the effect of 10 days of intermittent fasting on high-intensity type exercises, Wingate anaerobic (WT) and prolonged high-intensity time-to-exhaustion (HIT) cycling test. Twenty participants were randomised into an intermittent fasting (FAS) and a control group (CON). One day after baseline data collection on Day-0 where participants consumed their recommended daily caloric intake (FAS = 2500 ± 143 kcal day-1; CON = 2492 ± 20 kcal day-1) served over a course of five meals, the FAS group consumed only four meals where 40% was restricted by the omission of lunch (FAS = 1500 ± 55 kcal day-1). This diet was then continued for 10 days. Data on exercise performance and other dependent variables were collected on Day-2, -4, -6, -8 and -10. A reduction in WT power in the FAS group was observed on Day-2 (821.74 ± 66.07 W) compared to Day-0 (847.63 ± 95.94 W) with a moderate effect size (p < .05, ES = 0.4), while HIT time-to-exhaustion performance declined over the 10 days with a trend of recovery from a large to a minimum effect size (p < .05, ES = 0.8-0.3). Body weight and triglyceride were consistently reduced in the FAS group (p < .01). The present study suggests that intermittent fasting must exceed 10 days to ensure that high-intensity performance does not deteriorate because this length of time seems to be required for effective adaptation to the new dietary regimen.
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5.
Repeated-sprint training in the fasted state during Ramadan: morning or evening training?
Aloui, A, Driss, T, Baklouti, H, Jaafar, H, Hammouda, O, Chamari, K, Souissi, N
The Journal of sports medicine and physical fitness. 2018;(7-8):990-997
Abstract
BACKGROUND The present study assessed the optimal moment of the day for repeated-sprint training in the fasted state during Ramadan. METHODS Thirty amateur soccer players were randomly assigned to a morning training group (MTG, training at ~08:00 a.m., N.=10), an evening training group (ETG, training around 06:00 p.m., N.=10), and a control group (N.=10). Training sessions, conducted on alternate days, consisted of 3 sets of 6×40-m shuttle sprints (2×20 m with 180° direction changes). A 20-second passive recovery and a 4-minute passive recovery were allowed between repetitions and sets, respectively. Before and after Ramadan, performance was assessed at both 08:00 a.m. and 06:00 p.m. by Countermovement Jump (CMJ), Repeated-Sprint Test (RST), and Yo-Yo Intermittent Recovery Test Level 1 (YYIRT1). RESULTS After Ramadan, YYIRT1 performances were enhanced for both groups in the morning (7.82% and 6.29% for MTG and ETG, respectively, P<0.05), and in the evening (6.61% and 11.20%, respectively, P<0.05). Relative changes in YYIRT1 (P=0.33) and RST (-2.13% and -3.44% for MTG and ETG, respectively, P=0.49) at the specific time of training were similar for both groups. No differences were observed in CMJ performances before and after Ramadan for any group (P>0.05). CONCLUSIONS Morning or evening repeated-sprint training conducted in the fasted state during Ramadan enhanced soccer-specific endurance similarly.
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Three Days of Intermittent Fasting: Repeated-Sprint Performance Decreased by Vertical-Stiffness Impairment.
Cherif, A, Meeusen, R, Farooq, A, Ryu, J, Fenneni, MA, Nikolovski, Z, Elshafie, S, Chamari, K, Roelands, B
International journal of sports physiology and performance. 2017;(3):287-294
Abstract
PURPOSE To examine the effects of 3 d of intermittent fasting (3d-IF: abstaining from eating/drinking from dawn to sunset) on physical performance and metabolic responses to repeated sprints (RSs). METHODS Twenty-one active males performed an RS test (2 sets: 5 × 5-s maximal sprints with 25 s of recovery between and 3 min of recovery between sets on an instrumented treadmill) in 2 conditions: counterbalanced fed/control session (CS) and fasting session (FS). Biomechanical and biochemical markers were assessed preexercise and postexercise. RESULTS Significant main effects of IF were observed for sprints: maximal speed (P = .016), mean speed (P = .015), maximal power (P = .035), mean power (P = .049), vertical stiffness (P = .032), and vertical center-of-mass displacement (P = .047). Sprint speed and vertical stiffness decreased during the 1st (P = .003 and P = .005) and 2nd sprints (P = .046 and P = .048) of set 2, respectively. Postexercise insulin decreased in CS (P = .023) but not in FS (P = .230). Free-fatty-acid levels were higher in FS than in CS at preexercise (P < .001) and at postexercise (P = .009). High-density lipoprotein cholesterol (HDL-C) was higher at postexercise in FS (1.32 ± 0.22 mmol/L) than in CS (1.26 ± 0.21 mmol/L, P = .039). The triglyceride (TG) concentration was decreased in FS (P < .05) compared with CS. CONCLUSIONS 3d-IF impaired speed and power through a decrease in vertical stiffness during the initial runs of the 2nd set of RS. The findings of the current study confirmed the benefits of 3d-IF: improved HDL-C and TG profiles while maintaining total cholesterol and low-density lipoprotein cholesterol levels. Moreover, improving muscle power might be a key factor to retain a higher vertical stiffness and to partly counteract the negative effects of intermittent fasting.
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Effects of Intermittent Fasting, Caloric Restriction, and Ramadan Intermittent Fasting on Cognitive Performance at Rest and During Exercise in Adults.
Cherif, A, Roelands, B, Meeusen, R, Chamari, K
Sports medicine (Auckland, N.Z.). 2016;(1):35-47
Abstract
The aim of this review was to highlight the potent effects of intermittent fasting on the cognitive performance of athletes at rest and during exercise. Exercise interacts with dietary factors and has a positive effect on brain functioning. Furthermore, physical activity and exercise can favorably influence brain plasticity. Mounting evidence indicates that exercise, in combination with diet, affects the management of energy metabolism and synaptic plasticity by affecting molecular mechanisms through brain-derived neurotrophic factor, an essential neurotrophin that acts at the interface of metabolism and plasticity. The literature has also shown that certain aspects of physical performance and mental health, such as coping and decision-making strategies, can be negatively affected by daylight fasting. However, there are several types of intermittent fasting. These include caloric restriction, which is distinct from fasting and allows subjects to drink water ad libitum while consuming a very low-calorie food intake. Another type is Ramadan intermittent fasting, which is a religious practice of Islam, where healthy adult Muslims do not eat or drink during daylight hours for 1 month. Other religious practices in Islam (Sunna) also encourage Muslims to practice intermittent fasting outside the month of Ramadan. Several cross-sectional and longitudinal studies have shown that intermittent fasting has crucial effects on physical and intellectual performance by affecting various aspects of bodily physiology and biochemistry that could be important for athletic success. Moreover, recent findings revealed that immunological variables are also involved in cognitive functioning and that intermittent fasting might impact the relationship between cytokine expression in the brain and cognitive deficits, including memory deficits.
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8.
Ramadan and sport: minimizing effects upon the observant athlete.
Shephard, RJ
Sports medicine (Auckland, N.Z.). 2013;(12):1217-41
Abstract
The intermittent fasting of Ramadan could affect various aspects of body physiology and biochemistry important to athletic success. Much of the available information on this subject has been collected from sedentary subjects or low-level competitors, often without well matched controls. Other issues requiring clearer definition include the duration of fasting, the local environment, the timing of observations, and changes in training, diet and sleep patterns. Sleep may be shortened or made good with daytime naps. Circadian rhythms of temperature, metabolism, hormonal secretions and physical performance may be disrupted and incidental activities curtailed. Disturbances of psychomotor performance include daytime sleepiness, impaired vigilance and slower reactions. Food intake is limited to night-time meals. Sedentary individuals sometimes exploit Ramadan to reduce body fat stores. Well disciplined athletes usually maintain energy balance unless daily energy expenditures are very high. Protein intake must allow for gluconeogenesis, and provide quality protein ingested around training times. Blood sugar levels are likely to fall over a long and active day, even if morning glycogen reserves are maximized. Metabolism of fat should be encouraged, beginning prior to Ramadan; inclusion of fat in the pre-dawn meal also slows gastric emptying. Daytime fluid depletion is inevitable if athletes exercise in the heat, but the immediate deficit can usually be made good at night. Some studies show an initial fluid depletion, with recovery as Ramadan continues, possibly reflecting changes in urine and sweat production. Top athletes can maintain training throughout Ramadan, although coaches sometimes reduce demands through a pre-competitive tapering of effort. Late night or early morning training requires negotiation with players who are not observing Ramadan, and dietary adjustments to maintain optimal plasma amino acid levels when training. Performance of repeated anaerobic exercise is impaired, but aerobic power and muscular strength show little change during Ramadan. Ratings of fatigue are increased, and vigilance and reaction times are impaired, particularly during the afternoon. Medical issues during Ramadan are few. Athletes with diabetes mellitus should seek a medical exemption from fasting, and prescribed drug schedules should be carefully maintained. There is no major increase of injury rates, but competitors may have difficulty in producing urine for doping controls. Logical measures to minimize the effects of Ramadan include the optimization of mood state, maintenance of training, minimization of sleep loss, appropriate adjustments of diet, and the monitoring of competitors for chronic dehydration. Future research should concentrate on the changes observed in top athletes, particularly women, with data collected in the late afternoon after a known period of fasting in a well defined environment. It will be important to ensure that the lifestyle of those studied has been optimized. Implications of chronic dehydration for doping control also merit further investigation. Current data suggest that the impact of Ramadan upon athletic performance is small relative to the precision of test procedures, although it may be sufficient to cause a loss of medals. Negative effects vary widely with the type of sport, the season when fasting is observed, the local culture and the discipline exercised by the athlete.
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Does intermittent pneumatic leg compression enhance muscle recovery after strenuous eccentric exercise?
Cochrane, DJ, Booker, HR, Mundel, T, Barnes, MJ
International journal of sports medicine. 2013;(11):969-74
Abstract
Intermittent pneumatic compression (IPC) has gained rapid popularity as a post-exercise recovery modality. Despite its widespread use and anecdotal claims for enhancing muscle recovery there is no scientific evidence to support its use. 10 healthy, active males performed a strenuous bout of eccentric exercise (3 sets of 100 repetitions) followed by IPC treatment or control performed immediately after exercise and at 24 and 48 h post-exercise. Muscular performance measurements were taken prior to exercise and 24, 48 and 72 h post-exercise and included single-leg vertical jump (VJ) and peak and average isometric [knee angle 75º] (ISO), concentric (CON) and eccentric (ECC) contractions performed at slow (30° · s⁻¹) and fast (180° · s⁻¹) velocities. Plasma creatine kinase (CK) samples were taken at pre- and post-exercise 24, 48 and 72 h. Strenuous eccentric exercise resulted in a significant decrease in peak ISO, peak and average CON (30° · s⁻¹) at 24 h compared to pre-exercise for both IPC and control, however VJ performance remained unchanged. There were no significant differences between conditions (IPC and control) or condition-time interactions for any of the contraction types (ISO, CON, ECC) or velocities (CON, ECC 30° · s⁻¹ and 180° · s⁻¹). However, CK was significantly elevated at 24 h compared to pre-exercise in both conditions (IPC and control). IPC did not attenuate muscle force loss following a bout of strenuous eccentric exercise in comparison to a control. While IPC has been used in the clinical setting to treat pathologic conditions, the parameters used to treat muscle damage following strenuous exercise in healthy participants are likely to be very different than those used to treat pathologic conditions.
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The effect of time-of-day and Ramadan fasting on anaerobic performances.
Chtourou, H, Hammouda, O, Chaouachi, A, Chamari, K, Souissi, N
International journal of sports medicine. 2012;(2):142-7
Abstract
This study was designed to assess the effects of Ramadan-intermittent-fasting (RIF) and time-of-day on muscle power and fatigue during the Wingate test. In a randomized design, 10 football players completed a Wingate test at 07:00 and 17:00 h on 3 different occasions: one week before Ramadan (BR), the second week of Ramadan (SWR) and the fourth week of Ramadan (ER). There was an interval of 36-h between any 2 successive tests. During the Wingate test, peak power (PP), mean power (MP) and the fatigue index (FI) were recorded. While PP, MP and FI were greater in the evening than in the morning during BR (p<0.001), these diurnal variations in muscle power disappeared during the month of Ramadan (i. e., SWR and ER) due to a significant decrease in PP and MP in the evening (p<0.001). However, the diurnal variation in FI when measured at 17:00 h increased during this month (p<0.001). In addition, ratings of perceived exertion and fatigue were higher in the evening during Ramadan in comparison with BR. These results suggest that Ramadan might modify the circadian rhythm of muscle power and fatigue during the Wingate test by decreasing power output and increasing muscle fatigue at the time of the acrophase.