Megan A. Kuikman

Nutrition is a key determinant of cycling performance, underpinning the ability to optimize on-bike performance, support training adaptation and recovery, and maintain rider health and well-being. While these goals are shared across disciplines, the diverse physiological demands and logistical constraints of different cycling disciplines present distinct nutritional challenges. In recognition of both the importance of nutrition and the diverse individual and discipline-specific demands of cycling, the Union Cycliste Internationale Sports Nutrition Project was established and led by a steering committee that synthesized the expertise of 54 researchers to identify key nutritional requirements for elite cycling and develop recommendations that account for both individual and discipline-specific needs. These insights were published within a series of 14 topic-specific reviews. In this position statement, we present the principal take-home messages from the overall project, organized into 10 overarching themes spanning performance preparation, in-competition fueling, recovery and adaptation, energy availability, physique management, protecting against illness and injury, technological support, the use of supplements and sports foods, and age- and sex-specific considerations. Cycling-specific considerations are used to develop targeted nutritional recommendations within each of these themes, and high-priority future research directions are identified.

Introduction: Energy availability (EA), defined as (energy intake [EI]—exercise energy expenditure [EEE])/fat free mass (FFM), has been studied in relation to athlete health and performance. We implemented a standardised audit protocol to assess the quality and characteristics of research that has calculated or manipulated EA in humans, and in particular, athletic populations. Methods: Using the Smith et al. 2020 standardised protocol, we searched the PubMed database in June 2024 and October 2025 to identify human studies that directly assessed or manipulated EA. Exclusion criteria for our audit were indirect measurements of EA (questionnaire or survey), measurement of energy balance only, studies of diseased populations or reports in languages other than English. The included publications were assessed across the following metrics: population, athletic calibre, menstrual classification, study design and EA methodology. Results: Of the 203 publications included in the audit, most included females (70%) or studied females alone (50%). High-performance athletes were well represented (45%; tiers 3–5) particularly among studies involving EA assessments. The audit system for evaluating the quality of menstrual status assessment found that 57% used techniques graded as ‘gold,’ ‘silver,’ and ‘bronze,’ yet a large proportion (43%) provided insufficient terminology or detail to classify female participants’ menstrual status (‘ungraded’). Most publications included naturally menstruating females (54%), while others included athletes with menstrual irregularities (28%) or those using hormonal contraceptives (18%). In studies observing EA ( n = 146), food records (82%) and metabolic equivalent scores (METs) (40%) were predominantly used to assess EI and EEE, respectively. Among intervention studies involving EA manipulations ( n = 57), most provided food to participants (77%) and determined EEE by physiologically derived methods (70%) such as indirect calorimetry or heart rate. Discussion/Conclusions: High performance female athletes (tiers 3–5) are well-represented in EA research compared with other areas of sports science/medicine research. Despite the well-known association between EA and menstrual dysfunction, many EA studies failed to use high-quality methodology to describe or account for menstrual characteristics of female participants. The quality of such research will improve with better standardisation and characterisation of menstrual cycles of female participants and with further investigation of differences in the causes of and responses to low EA (LEA) exposure in male athletes. A standardised calculation of EA and best practice protocols for its assessment may improve the quality of EA studies, however, a need to focus on intervention studies rather than assessment of EA in free-living athletes is necessary to better understand the effects of LEA exposure on health and performance.

Maintaining adequate energy availability is a key concern for many cyclists, many of whom must balance the need to support their very high training and competition energy expenditure while simultaneously adopting nutritional strategies that will allow them to maintain the body mass deemed most conducive to optimal performance. Available evidence indicates that cyclists tend to be a weight-conscious group that frequently reports engaging in restrictive eating behaviors. Together, the dual demands of supporting the energetic cost of their training alongside restricting energy intake to maintain a low body mass may place some riders at a high risk of experiencing negative health- and performance-related consequences associated with prolonged and problematically low energy availability. Within this review, we critically discuss issues related to the role of body mass and composition in cycling performance along with cyclists’ reported perceptions on this issue. We also describe evidence on reported energy expenditure and intake in high-level cyclists, recognizing the challenges of accurate assessment of these parameters, particularly within the field setting. Evidence related to signs and signals of problematic low energy availability in cyclists is described, also recognizing the complexity of determining causality for longer term low energy availability consequences alongside identifying other potential contributory factors to the symptomatology reported for this population. Finally, we make pragmatic recommendations to support cyclists to meet their physique goals while simultaneously emphasizing and supporting longer term health, performance, and well-being.

Purpose: The objective of this study is to investigate the effects of acute diet and exercise manipulation on resting metabolic rate (RMR) measurement variability and dual-energy x-ray absorptiometry (DXA) body composition estimates. Methods: Ten male and 10 female endurance athletes (12 cyclists, 5 triathletes, 4 runners) of tier 2 (n = 18) to tier 3 (n = 2) caliber underwent five conditions using a Latin square counterbalance design. For 24 h, athletes consumed a diet providing excessive energy availability (EA) (75 kcal⋅kg fat-free mass (FFM)⁻¹) without exercise (GEA_rest), high-EA (45 kcal⋅kg FFM⁻¹) without (HEA_rest) or with exercise (HEA_ex), or low-EA (15 kcal⋅kg FFM⁻¹) without (LEA_rest) or with exercise (LEA_ex). Exercise involved two bouts of cycling (morning bout: 149 ± 34 min at 55% of maximal aerobic capacity (V̇O_2max); afternoon bout: 60 min at 65% of V̇O_2max) that resulted in a cumulative exercise energy expenditure of 30 kcal⋅kg FFM⁻¹. The following day, RMR and DXA measurements occurred after a 10-h fast and 12-h postexercise. Results: There were neither sex differences in relative RMR (P = 0.158) nor effects of any of the five conditions on RMR (P = 0.358). For both male and female athletes, FFM estimates were decreased following the LEA_rest (−0.84 ± 0.66 kg; P = 0.001) and LEA_ex (−0.65 ± 0.86 kg; P = 0.016) conditions compared with the GEA_rest condition and following the LEA_rest (−0.73 ± 0.51 kg; P = 0.001) and LEA_ex (−0.54 ± 0.79 kg; P = 0.024) conditions compared with the HEA_ex condition. There was no effect of condition on fat mass estimates (P = 0.819). Conclusions: Acute periods of diet and exercise manipulation did not create artifacts in next-day RMR measurements. However, as changes in estimates of FFM were seen, diet and exercise should be controlled in the 24-h before DXA scans.

Purpose: This study aimed to investigate the temporal effects of ~1800 m altitude exposure and energy availability (EA) manipulation on resting metabolic rate (RMR). Methods: Twenty elite female race walkers underwent a 3-wk training camp at an altitude of ~1800 m. During the first 2 wk, athletes consumed a high EA (HEA) diet of 45 kcal·kg fat-free mass (FFM)⁻¹·d⁻¹. During the final week, half the athletes consumed a low EA (LEA) diet of 15 kcal·kg FFM⁻¹·d⁻¹, whereas the others continued on an HEA diet. Athletes followed individualized training plans throughout the study. To assess the effect of altitude on RMR, athletes in the HEA group had RMR measured at baseline (~580 m) before altitude exposure (Pre-alt), at 36 h (36h-alt), 2 wk (Wk2-alt), and 3 wk into altitude exposure (Wk3-alt), and at 36 h post-altitude exposure at ~580 m (36h-post). To assess the effect of LEA exposure on RMR while at altitude, athletes in the LEA group underwent RMR measurements at Pre-alt and before (Wk2-alt) and after the 7 d of LEA (Wk3-alt). Results: Compared with Pre-alt, the RMR of HEA athletes was increased at 36h-alt (+5.3% ± 3.1%; P = 0.026) and Wk2-alt (+4.9% ± 4.9%; P = 0.049), but was no longer elevated at Wk3-alt (+1.7% ± 4.2%; P = 0.850). The RMR of HEA athletes at 36h-post was lower than all timepoints at altitude (P < 0.05) but was not different from Pre-alt (−3.9% ± 7.2%; P = 0.124). The 7-d period of LEA exposure at altitude did not affect RMR (P = 0.347). Conclusions: RMR was transiently increased with ~1800-m altitude exposure in female athletes and was unaffected by short-term LEA. However, the altitude-induced increase was small (~25–75 kcal·d⁻¹) and was unlikely to have clinically significant implications for daily energy requirements.

The cyclical changes in sex hormones across the menstrual cycle (MC) are associated with various biological changes that may alter resting metabolic rate (RMR) and body composition estimates. Hormonal contraceptive (HC) use must also be considered given their impact on endogenous sex hormone concentrations and synchronous exogenous profiles. The purpose of this study was to determine if RMR and dual-energy X-ray absorptiometry body composition estimates change across the MC and differ compared with HC users. This was accomplished during a 5-week training camp involving naturally cycling athletes (n = 11) and HC users (n = 7 subdermal progestin implant, n = 4 combined monophasic oral contraceptive pill, n = 1 injection) from the National Rugby League Indigenous Women’s Academy. MC phase was retrospectively confirmed via serum estradiol and progesterone concentrations and a positive ovulation test. HC users had serum estradiol and progesterone concentrations assessed at the time point of testing. Results were analyzed using general linear mixed model. There was no effect of MC phase on absolute RMR (p = .875), relative RMR (p = .958), or dual-energy X-ray absorptiometry body composition estimates (p > .05). There was no effect of HC use on absolute RMR (p = .068), relative RMR (p = .309), or fat mass estimates (p = .766), but HC users had a greater fat-free mass and lean body mass than naturally cycling athletes (p = .028). Our findings suggest that RMR and dual-energy X-ray absorptiometry body composition estimates do not significantly differ due to changes in sex hormones in a group of athletes, and measurements can be compared between MC phases or with HC usage without variations in sex hormones causing additional noise.

The aim of this audit was to assess the representation of female athletes, dietary control methods, and gold standard female methodology that underpins the current guidelines for chronic carbohydrate (CHO) intake strategies for athlete daily training diets. Using a standardized audit, 281 studies were identified that examined high versus moderate CHO, periodized CHO availability, and/or low CHO, high fat diets. There were 3,735 total participants across these studies with only ∼16% of participants being women. Few studies utilized a design that specifically considered females, with only 16 studies (∼6%) including a female-only cohort and six studies (∼2%) with a sex-based comparison in their statistical procedure, in comparison to the 217 studies (∼77%) including a male-only cohort. Most studies (∼72%) did not provide sufficient information to define the menstrual status of participants, and of the 18 studies that did, optimal methodology for control of ovarian hormones was only noted in one study. While ∼40% of male-only studies provided all food and beverages to participants, only ∼20% of studies with a female-specific design used this approach for dietary control. Most studies did not implement strategies to ensure compliance to dietary interventions and/or control energy intake during dietary interventions. The literature that has contributed to the current guidelines for daily CHO intake is lacking in research that is specific to, or adequately addresses, the female athlete. Redressing this imbalance is of high priority to ensure that the female athlete receives evidence-based recommendations that consider her specific needs.

Purpose: The aim of this audit was to assess the representation of female athletes within the literature that has led to current guidelines for carbohydrate (CHO) intake in the acute periods surrounding exercise and the quality of this research. Methods: We conducted a standardized audit of research assessing CHO loading protocols, CHO mouth rinse, and CHO intake before, during, and after exercise. Results: A total of 937 studies were identified in this audit. There were a total of 11,202 participants across these studies, with only ~11% being women. Most studies involved male-only cohorts (~79%), with a mere 38 studies (~4%) involving female-only cohorts and 14 studies (~2%) including a methodological design for comparison of sex-based responses. The frequent use of incorrect terminology surrounding menstrual status and the failure of most studies (~69%) to provide sufficient information on the menstrual status of participants suggests incomplete understanding and concern for female-specific considerations among researchers. Of the 197 studies that included women, only 13 (~7%) provided evidence of acceptable methodological control of ovarian hormones, and no study met all best-practice recommendations. Of these 13 studies, only half also provided sufficient information regarding the athletic caliber of participants. The topics that received such scrutiny were CHO loading protocols and CHO intake during exercise. Conclusions: The literature that underpins the current guidelines for CHO intake in the acute periods around exercise is lacking in high-quality research that can contribute knowledge specific to the female athlete and sex-based differences. New research that considers ovarian hormones and sex-based differences is needed to ensure that the recommendations for acute CHO fueling provided to female athletes are evidence based.

Micronutrient deficiencies and sub-optimal intakes among female athletes are a concern and are commonly prevented or treated with medical supplements. However, it is unclear how well women have been considered in the research underpinning current supplementation practices. We conducted an audit of the literature supporting the use of calcium, iron, and vitamin D. Of the 299 studies, including 25,171 participants, the majority (71%) of participants were women. Studies with exclusively female cohorts (37%) were also more prevalent than those examining males in isolation (31%). However, study designs considering divergent responses between sexes were sparse, accounting for 7% of the literature. Moreover, despite the abundance of female participants, the quality and quantity of the literature specific to female athletes was poor. Just 32% of studies including women defined menstrual status, while none implemented best-practice methodologies regarding ovarian hormonal control. Additionally, only 10% of studies included highly trained female athletes. Investigations of calcium supplementation were particularly lacking, with just two studies conducted in highly trained women. New research should focus on high-quality investigations specific to female athletes, alongside evaluating sex-based differences in the response to calcium, iron, and vitamin D, thus ensuring the specific needs of women have been considered in current protocols involving medical supplements.

Both dietary and exercise behaviors need to be considered when examining underlying causes of low energy availability (LEA). The study assessed if exercise dependence is independently related to the risk of LEA with consideration of disordered eating and athlete calibre. Via survey response, female (n = 642) and male (n = 257) athletes were categorized by risk of: disordered eating, exercise dependence, disordered eating and exercise dependence, or if not presenting with disordered eating or exercise dependence as controls. Compared to female controls, the likelihood of being at risk of LEA was 2.5 times for female athletes with disordered eating and >5.5 times with combined disordered eating and exercise dependence. Male athletes with disordered eating, with or without exercise dependence, were more likely to report signs and symptoms compared to male controls-including suppression of morning erections (OR = 3.4; p < 0.0001), increased gas and bloating (OR = 4.0–5.2; p < 0.002) and were more likely to report a previous bone stress fracture (OR = 2.4; p = 0.01) and ≥22 missed training days due to overload injuries (OR = 5.7; p = 0.02). For both males and females, in the absence of disordered eating, athletes with exercise dependence were not at an increased risk of LEA or associated health outcomes. Compared to recreational athletes, female and male international caliber and male national calibre athletes were less likely to be classified with disordered eating.