Effects of caloric restriction and overnight fasting on cycling endurance performance

[Effects of intermittent fasting and sports performance: a narrative review]

Recently, fasted exercise has generated interest for its potential to stimulate metabolic and performance adaptations. The present study aims to analyze the effects of fasting and fasted training on performance and metabolism, acutely and chronically. The databases Medline (PubMed), Physiotherapy Evidence Database (PEDro), Cochrane, and Google Scholar were searched. In total, 767 studies were identified. Of those, 51 studies were finally included. Acutely, exercise on fasting promotes fat oxidation at low and moderate intensities, while protein catabolism is not increased. Performance is not affected in efforts lower than 1 hour. Chronically, fasting generates greater efficiency in fat metabolism and the ability to regulate blood glucose in the long term, although it has not been possible to determine whether these findings improve sports performance. More research is needed in elite athletes, with high training loads and with a periodized approach to fasting.

Preliminary Evaluation of Self-Reported Training Volume as an Adjunct Measure of Female Athlete Triad Risk in Division 1 Collegiate Female Runners

Background/Objectives: This study tested whether self-reported training volume is predictive of female athlete triad risk collected using an established twelve-question triad screening tool in National Collegiate Athletic Association (NCAA) Division I (DI) collegiate female runners. Methods: A total of 319 institutions were initially contacted, seven of which agreed to distribute surveys to their female cross-country and track and field athletes. A total of 41 of 149 respondents completed the survey and met all inclusion criteria. Linear and binomial logistic regressions examined the relationships between self-reported training volumes and estimated triad risk. Independent samples t-tests were also used to compare training volumes across the high (> 50th percentile for risk factor counts) vs. low-risk groups. Results: Total weekly competition and conditioning resistance training hours were associated with the total number of triad risk factors (p = 0.044) and were also predictive of the triad risk group (p = 0.037). Likewise, both competition and conditioning resistance training hours (p = 0.034) were higher in the high-risk group versus the low-risk group. Conclusions: These findings suggest that self-reported resistance training volume is predictive of triad risk, but additional research is required to determine if monitoring training volume can provide valuable, real-time assessments of triad risk in DI collegiate female runners.

The Effects of 24-h Fasting on Exercise Performance and Metabolic Parameters in a Pilot Study of Female CrossFit Athletes

Many studies have tested intermittent fasting (IF) in athletes, but its effects on female CrossFit athletes remain relatively unexplored in the existing literature. The aim of this study was to evaluate and compare the effects of 24-h IF on the physical performance of female CrossFit practitioners. Eleven female CrossFit athletes (age: 30.91 ± 3.42, weight: 65.26 ± 7.55 kg, height: 1.66 ± 0.05 m) participated in the study. The study used a crossover design with fasting and eating conditions. Participants completed an exercise test, standing long jump, and handgrip strength assessment. Hydration status, heart rate, blood lactate, blood glucose, rates of perceived exertion, and hunger were measured. Results showed significant differences in blood lactate concentration (F = 5.435, p = 0.042, η2p = 0.352). Resting blood lactate concentration was significantly lower in the fasting trial than in the eating trial (p < 0.001), but post-exercise blood lactate concentrations were higher in the fasting trial than in the eating trial (p < 0.001). No differences were found in performance times (p > 0.05). In conclusion, this pilot study of females suggests that 24-h fasting does not impair exercise performance or negatively affect physiological parameters in CrossFit athletes.

The impact of dieting culture is different between sexes in endurance athletes: a cross-sectional analysis

Background

Frequent dieting is common in athletes attempting to achieve a body composition perceived to improve performance. Excessive dieting may indicate disordered eating (DE) behaviors and can result in clinical eating disorders. However, the current nutrition patterns that underly dieting culture are underexplored in endurance athletes. Therefore, the purpose of this study was to identify the sex differences in nutrition patterns among a group of endurance athletes.

Methods

Two-hundred and thirty-one endurance athletes (females = 124) completed a questionnaire regarding their dieting patterns and associated variables.

Results

The majority of athletes did not follow a planned diet (70.1%). For endurance athletes on planned diets (n = 69), males were more likely follow a balanced diet (p = 0.048) and females were more likely to follow a plant-based diet (p = 0.021). Female endurance athletes not on a planned diet (n = 162) were more likely to have attempted at least one diet (p < 0.001). Male athletes attempted 2.0 ± 1.3 different diets on average compared to 3.0 ± 2.0 for females (p = 0.002). Female athletes were more likely to attempt ≥ three diets (p = 0.022). The most common diet attempts included carbohydrate/energy restrictive, plant-based, and elimination diets. Females were more likely to attempt ketogenic (p = 0.047), low-carbohydrate (p = 0.002), and energy restricted diets (p = 0.010). Females made up the entirety of those who attempted gluten-/dairy-free diets (F = 22.0%, M = 0.0%).

Conclusions

Being a female athlete is a major determinant of higher dieting frequency and continual implementation of popular restrictive dietary interventions. Sports dietitians and coaches should prospectively assess eating behavior and provide appropriate programming, education, and monitoring of female endurance athletes.

Fasting-Mimicking-Diet does not reduce skeletal muscle function in healthy young adults: a randomized control trial

PURPOSE

The aim of this study was to evaluate the short- and long-term effects of the Fasting-Mimicking-Diet (FMD) intervention on neuromuscular parameters of force production in healthy young men.

METHODS

Twenty-four physically active men completed the study. Participants were randomly assigned to Fasting-Mimicking (FMD) or Normal Diet (ND) and asked to follow three cycles of dietary intervention. Neuromuscular parameters of force production during maximal voluntary isometric contractions (MVCs) with the leg extensors muscles and anthropometrics were measured at baseline (T0), at the end of the first cycle (T1), and 7-10 days after the 3rd cycle of the nutritional intervention (T2). The study was registered on Clinicaltrials.gov (No. NCT04476615).

RESULTS

There was a significant decrease in body mass at T1 for FMD (- 2.6 kg, ∆ from baseline, on average; p < 0.05) but not in ND (- 0.1 kg;). Neuromuscular parameters of force production, muscle volume, and MVC torque did not change or differ between groups across visits. Results were similar even when parameters were normalized by muscle volume.

CONCLUSION

The consumption of FMD in a group of young healthy male subjects showed to be feasible, and it did not affect neuromuscular parameters of force production. The results suggest that FMD could be safely adopted by strength athletes without detrimental effects on force and muscle volume. Further research in clinical population at risk of muscle mass loss, such as elderly and obese subjects with sarcopenia, is warranted.

Effects of Time-Restricted Feeding on Supramaximal Exercise Performance and Body Composition: A Randomized and Counterbalanced Crossover Study in Healthy Men

Using a crossover design, we explored the effects of both short- and long-term time-restricted feeding (TRF) vs. regular diet on Wingate (WnT) performance and body composition in well-trained young men. Twelve healthy male physical education students were included (age: 22.4 ± 2.8 years, height: 174.0 ± 7.1 cm, body mass: 73.6 ± 9.5 kg, body mass index: 24.2 ± 2.0 kg/m²). The order of dieting was randomized and counterbalanced, and all participants served as their own controls. TRF was limited to an 8-h eating window and non-TRF involved a customary meal pattern. Participants performed WnT tests and body composition scans at baseline, post-one and post-four weeks of the assigned diet. Before testing, participants were asked to fill out a dietary record over four consecutive days and were instructed to continue their habitual training throughout the study. Energy intake and macronutrient distribution were similar at baseline in both conditions. WnT mean power and total work output increased post-four weeks of TRF. Both conditions were similarly effective in increasing fat-free mass after four weeks of intervention. However, there was no correlation between change in fat-free mass and WnT mean power after TRF. TRF did not elicit any changes in WnT performance or body composition one week post-intervention. Thus, long-term TRF can be used in combination with regular training to improve supramaximal exercise performance in well-trained men.

Anti-fatigue Effects of Santé Premium Silver Perch Essence on Exhaustive Swimming Exercise Performance in Rats

Aim: Fish soup is a traditional Chinese food usually offered as a healthy supplement to elders, pregnant women and persons who just had surgery. Silver perch (Santé premium silver perch essence, SPSPE) extract contains various quality proteins, collagen, minerals, trace elements, and branch chain amino acids (BCAA) that could help individuals recover from exhaustion and control body weight. However, there are very limited studies exploring the effects of fish extracts on exercise performance and fatigue, and relevant physiological mechanisms. Therefore, the purpose of this study was to investigate the effects of chronic SPSPE administration on exhaustive exercise performance.

Method: Male Wistar rats weighing around 250 g were divided into 4 groups: Control, 1X SPSPE (6.2 ml/kg), 2X SPSPE (12.4 ml/kg) and 5X SPSPE (31.0 ml/kg). Rats were administrated SPSPE by oral gavage feeding every day for 33 days. Their body weight were measured every week. Before and after the exhaustive swimming test, the blood was collected for circulating lactate, glucose, ammonia, hormones, and myoglobin analysis. Rats were sacrificed after performing an exhaustive swimming exercise test. The liver tissues were collected for glycogen content and H&E staining.

Results: After the administration of 1X and 5X SPSPE, swimming fatigue was significantly delayed (p = 0.024). There was no difference in the hormone plasma level between the control and SPSPE groups. The induction of plasma corticosterone and TBARS by exhaustive swimming exercise could be decreased by SPSPE administration. The increased plasma myoglobin concentration from exhaustive swimming exercise was weakened by SPSPE supplementation. The higher glycogen sparing contained in liver tissue was observed in SPSPE-treated groups (p < 0.05).

Conclusion: SPSPE could efficiently delay swimming fatigue through sparing of liver glycogen and attenuation of plasma TBARS, myoglobin induction by exhaustive exercise. Our findings provide a scientific-based fundamental information and better understanding for developing a fish extract-based anti-fatigue supplement.

Intermittent fasting compromises the performance of eutrophic rats submitted to resistance training

OBJECTIVES

The aim of this study was to analyze the effects of intermittent fasting (IF) on the performance of rats subjected to resistance training ladder climbs (RTLCs).

METHODS

Thirty-two Wistar rats (80-d-old) were placed into one of the following four groups (n = 8/group): control (C), which were fed a standard diet with no exercise; intermittent fasting (IF) rats underwent IF for 16 h/d, fed a standard diet for a period of 8 h/d with no exercise; trained control (TC) were fed a standard diet and submitted to RTLC; and trained intermittent fasting (TIF) underwent IF for 16 h/d, fed a standard diet for a period of 8 h/d, and submitted to RTLC. Training groups completed 6-wk of RTLC (3 × /wk). The maximal load test (MLT) was applied on two occasions: before the first RTLC session and at the end of week 6 of physical training. Its purpose was to compare changes in performance over time. Both blood collection and total extraction of the organs were performed at the end of the experimental period.

RESULTS

Food intake was higher in the TC group than in either the IF or TIF groups. TC supported a higher load (g) during the final MLT compared with the C, IF, and TIF groups, respectively. TC (initial MLT: 371.4 ± 31.1; final MLT: 593.9 ± 33.5) and TIF (initial MLT: 402.3 ± 31.8; final MLT: 495.4 ± 83.3) presented higher values when the pre- and post-RTLC moments were compared. The relative weight of the stomach was higher in TIF than in C and TC rats. There was no difference in aspartate transaminase and alanine transaminase enzyme activities or in creatinine and total cholesterol levels.

CONCLUSIONS

IF negatively affected RTLC performance. IF plus RTLC increased the relative weight of the stomach as well as reduced food intake, without an increase in body weight, suggesting this combination may have promoted dilation of this organ, due, hypothetically, to the scarcity of food for several hours and the energy expenditure generated by physical training.

The effect of 10 days of energy-deficit diet and high-intensity exercise training on the plasma high-density-lipoprotein (HDL) level among healthy collegiate males

ABSTRACTAn energy-deficit (ED) diet increases lipid mobilisation, while endurance exercise improves lipid profile by promoting formation of high-density lipoproteins (HDLs) among moderately active population. However, it is not clear whether ED with high-intensity exercise training can improve lipid profiles. Therefore, 20 recreationally active males (20.3 ± 2.7 years old with peak oxygen consumption (V˙O₂peak) of 2.8 ± 0.2 L min^-1) with HDL concentration of 1.44 ± 0.32 mmol L^-1, were evenly allocated to either an ED group (1590 ± 79 kcal day^-1: 40% of total caloric omitted at lunchtime) or a control (CON) group (2570 ± 139 kcal day^-1). Participants in both groups performed high-intensity cycling at 90% V˙O₂peak at a constant workload for 8 min, 2 h after breakfast on day D₀, D₂, D₄, D₆, D₈ and D₁₀ (D_n is day number), after which blood samples were collected. In ED, compared to D₀, triglycerides (TG) decreased on D_6-10 (p < .01) while total low-density lipoprotein (LDL), total cholesterol (TC) increased on D_2-10, while HDL progressively increased on D_6-10 (p = .01) with a final value of 1.67 ± 0.24 mmol L^-1. In CON, there were no changes in TG, TC and HDL while LDL was reduced on D_8-10 (p = .01). Moreover, the proportions of TC/HDL and LDL/HDL increased in ED on D_2-10 and D_2-8 (p = .05), respectively, while LDL/HDL in CON was reduced on D_8-10 (p = .01). In brief, 10 days of ED and a series of high-intensity exercise sessions show progressive elevation of HDL which suggest longer period is required to observe changes in lipid ratios.

Severe-intensity constant-work-rate cycling indicates that ramp incremental cycling underestimates ⩒o2max in a heterogeneous cohort of sedentary individuals

In the absence of a ⩒o2-work-rate plateau, debate continues regarding the best way to verify that the peak ⩒o2 achieved during incremental exercise (⩒o2peak) is the "true ⩒o2max." Oft-used "secondary criteria" have been questioned in conjunction with the contention that a severe-intensity constant-work-rate "verification bout" should be considered the "gold standard." The purpose of this study was to compare the ⩒o2peak during ramp incremental cycling (RAMP-INC) by a heterogeneous (with respect to body composition and sex) cohort of sedentary individuals with the ⩒o2peak during severe-intensity constant-work-rate cycling (CWR) performed after RAMP-INC at the highest work rate achieved. A secondary purpose was to determine the degree to which traditional and newly-proposed age-dependent secondary criteria (RER, HR) identified RAMP-INC which CWR confirmed were characterized by a submaximal ⩒o2peak. Thirty-five healthy male (n = 19: 33.4 ± 6.3 yrs) and female (26.8 ± 3.6 yrs) sedentary participants performed RAMP-INC followed by CWR. The ⩒o2peak values from the two tests were correlated (r = 0.96; p < 0.01; mean CV = 24%); however, ⩒o2peak for CWR was significantly greater (29.6 ± 7.2 v. 28.6 ± 6.8 mL∙min-1∙kg-1; p < 0.01) with a mean bias of 0.98 mL∙min-1∙kg-1 (z = -2.9, p < 0.01). Both traditional and newly-proposed criterion values for RER were achieved during RAMP-INC by 33 of 35 participants (including 21 of 23 who registered a higher ⩒o2peak on CWR). The traditional HR criterion value was achieved on only seven tests (three of which were confirmed to be characterized by a submaximal ⩒o2peak) while use of less stringent newly-proposed criteria resulted in acceptance of an additional seven tests of which five were confirmed to be submaximal. Severe-intensity CWR to limit of tolerance indicates that RAMP-INC underestimates ⩒o2max in sedentary individuals and both traditional and newly-proposed secondary criteria are ineffective for identifying such tests.

Mendonca G. Effects of Intermittent Fasting on Specific Exercise Performance Outcomes: A Systematic Review Including Meta-Analysis

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.

Exercise Training and Fasting: Current Insights

Fasting is defined as the abstinence from consuming food and/or beverages for different periods of time. Both traditional and modern healthcare systems recommend fasting as a therapeutic intervention for the management of several chronic, non-infectious diseases. Exercising during a fasting state increases lipolysis in adipose tissue while also stimulating peripheral fat oxidation, resulting in increased fat utilization and weight loss. A key focus of this review is to assess whether endurance training performed while fasting induces specific training adaptations, where increased fat oxidation improves long-term endurance levels. Fasting decreases body weight, lean body and fat content in both trained and untrained individuals. Several studies indicate a broader impact of fasting on metabolism, with effects on protein and glucose metabolism in sedentary and untrained subjects. However, there are conflicting data regarding the effects of fasting on glucose metabolism in highly trained athletes. The effects of fasting on physical performance indicators also remain unclear, with some reporting a decreased performance, while others found no significant effects. Differences in experimental design, severity of calorie restriction, duration, and participant characteristics could, at least in part, explain such discordant findings. Our review of the literature suggests that there is little evidence to support the notion of endurance training and fasting-mediated increases in fat oxidation, and we recommend that endurance athletes should avoid high intensity training while fasting.

Bone health in elite Norwegian endurance cyclists and runners: a cross-sectional study

Background

Athletes who compete in non-weight-bearing activities such as swimming and cycling are at risk of developing low bone mineral density (BMD). Athletes in long-distance running are at risk of low BMD.

Objective

(1) To evaluate the bone health in Norwegian male and female national elite road cyclists and middle-distance and long-distance runners, and to identify cases of low BMD. (2) To identify possible risk factors associated with low BMD.

Methods

Twenty-one runners (11 females and 10 males) and 19 road cyclists (7 females and 12 males) were enrolled in this cross-sectional study. Dual-energy X-ray absorptiometry measurement of BMD in total body, femoral neck and lumbar spine was measured. Participants completed a questionnaire regarding training, injuries, calcium intake and health variables.

Results

The cyclists had lower BMD for all measured sites compared with the runners (p≤0.05). Ten of 19 cyclists were classified as having low BMD according to American College of Sports Medicine criteria (Z-score ≤−1), despite reporting to train heavy resistance training on the lower extremities. Low BMD was site specific having occurred in the lumbar spine and the femoral neck and was not confined to females. Type of sport was the only factor significantly associated with low BMD.

Conclusion

National elite Norwegian road cyclists had lower BMD compared with runners, and a large proportion was classified as having low BMD, despite having performed heavy resistance training. Interventions to increase BMD in this population should be considered.

Calorie restriction regime enhances physical performance of trained athletes

Background

Caloric restriction induces mitochondrial biogenesis and improves physical fitness in rodents. We aimed to provide evidence of how caloric restriction affects the body composition and physical performance of trained athletes and to evaluate the possible impact of an every-other-day feeding diet on nutritional deficiencies of micronutrients and essential fatty acids.

Methods

The study was performed with 12 healthy male athletes by carrying out a 33% caloric restriction with respect to their usual diet. Athletes performed a maximal exercise stress test both before and after the caloric restriction period. Blood samples were taken before and after the caloric restriction at basal conditions and 30 min post-exercise. Although energy intake was reduced by about 33%, the contribution of carbohydrates, proteins, and lipids to total energy intake during the caloric restriction was similar to the original diet.

Results

The caloric restriction reduced the daily specific micronutrient intake to values lower than 90% of recommended dietary allowances. No effects were observed in blood parameters related to iron metabolism and tissue damage, glucose levels, lipid profiles, or erythrocyte fatty acid composition. In addition, oxidative damage markers decreased after the nutritional intervention. The caloric restriction intervention significantly reduced body weight and trunk, arm, and leg weights; it also caused a decrease in fat and lean body mass, the energy expenditure rate when performing a maximal exercise stress test, and the energy cost to run one meter at various exercise intensities. Furthermore, the intervention ameliorated the onset of the anaerobic phase of exercise.

Conclusion

A caloric restriction improves athletes' performance and energy efficiency, but reduces the daily intake of micronutrients; so, when caloric restriction programs are implemented micronutrient supplementation should be considered.

Trial registration

The project was registered at ClinicalTrials.gov (NCT02533479).

The effect of 10 days of intermittent fasting on Wingate anaerobic power and prolonged high-intensity time-to-exhaustion cycling performance

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.

Differential in Maximal Aerobic Capacity by Sex in Collegiate Endurance Athletes Consuming a Marginally Low Carbohydrate Diet

PURPOSE

Although current sports nutrition recommendations advocate for a high carbohydrate (CHO) intake among endurance athletes, recent research has suggested that training with low CHO availability may augment adaptations to aerobic training. The purpose of this study was to observe the dietary habits of collegiate distance runners and to investigate the effects of habitual CHO intake on aerobic performance [VO_2max(post)] during a competitive season.

METHODS

During an 8-week trial period, 12 (N = 12) collegiate track athletes recorded their self-selected dietary intake via 24-hour recall. Analysis of CHO intake was conducted by a registered dietitian. Pre [VO_2max (pre)] and post [VO_2max (post)] season aerobic capacity assessments were performed using a one-way analysis of covariance (ANCOVA) with 2 covariates controlling for VO_2max (pre) and CHO intake compared to the variance in VO_2max (pre) and VO_2max (post) by sex.

RESULTS

The average CHO was 4.11 ± 1.03 g/kg body mass (BM), with only one female athlete meeting dietary recommendations, consuming ≥ 6 g/kg BM. Male distance runners on average had a lower CHO than females. After adjusting for VO_2max (pre) and CHO, there were statistically significant differences between VO_2max (post) group means by sex with a difference of 12.62 ml/kg/min (95% confidence interval [CI], 2.12-23.12, p = 0.02), with CHO accounting for 18% of the variance in VO_2max (post).

CONCLUSION

Collegiate distance runners exhibited marked improvements in maximal aerobic capacity during the in-season while consuming a marginally low-CHO diet, with a predominant effect in males. Therefore, CHO intakes below current recommendations for endurance athletes might not be detrimental to aerobic training adaptations.

The effect of ramadan fasting on physical performances, mood state and perceived exertion in young footballers

Purpose

This study was designed to assess the effects of Ramadan fasting on the profile of mood state and perceived exertion in young soccer players and aerobic and anaerobic performances during the Yo-Yo, repeated sprint ability (RSA) and the Wingate tests.

Methods

Twenty junior male soccer players completed the Yo-Yo, the RSA, and the Wingate tests on three different occasions: one-week before Ramadan (BR), the second week (SWR) and the fourth week (ER) of Ramadan. The total distance (TD) covered and the estimated maximal aerobic velocity (MAV) during the Yo-Yo test were recorded. During the RSA test, peak power (PP) during each sprint, the percentage of decrement of PP (PD) and total work (Wtotal) were calculated. During the Wingate test, peak (P_peak) and mean (P_mean) powers and fatigue index (FI) were recorded.

Results

TD and MAV (P=0.01) during the Yo-Yo test and PP (P=0.01, P=0.004, P=0.001, P=0.01, P=0.03 for sprints 1, 2, 3, 4, and 5, respectively) and Wtotal (P=0.02) during the RSA test were significantly higher during BR than ER. Furthermore, muscle fatigue during the RSA test increased significantly from BR to ER (P=0.01). P_peak and P_mean during the Wingate test decreased significantly from BR to SWR and ER (P<0.0005). FI was higher during SWR (P=0.001) and ER (P<0.0005) than BR. In addition, rating of perceived exertion scores and fatigue estimated by the profile of mood state questionnaire were higher during Ramadan in comparison with BR.

Conclusions

The present study suggests that both aerobic and anaerobic performances during the Yo-Yo, the RSA and the Wingate tests were affected by Ramadan fasting in young soccer players.

Effects of Ramadan intermittent fasting on sports performance and training: a review

The month-long diurnal Ramadan fast imposes a major challenge to Islamic athletes. Sporting events are programmed throughout the year, with the result that training and competition are often scheduled during Ramadan. The small numbers of well-controlled studies that have examined the effects of Ramadan on athletic performance suggest that few aspects of physical fitness are negatively affected, and only modest decrements are observed. Whereas subjective feelings of fatigue and other mood indicators are often cited as implying additional stress on the athlete throughout Ramadan, most studies show these measures may not be reflected in decreases in performance. The development and early implementation of sensible eating and sleeping strategies can greatly alleviate the disruptions to training and competitiveness, thus allowing the athlete to perform at a high level while undertaking the religious intermittent fast. Nevertheless, further research is required to understand the mechanisms and energy pathways that allow athletes to maintain their performance capacities during Ramadan, and which factors are responsible for the observed decrements in performance of some individuals.