Alternate-Day Low Energy Availability During Spring Classics in Professional Cyclists

Abstract

Purpose: To assess energy and carbohydrate (CHO) availability and changes in blood hormones in 6 professional male cyclists over multiple single-day races. Methods: The authors collected weighed-food records, power-meter data, and morning body mass measurements across 8 d. CHO intakes were compared with contemporary guidelines. Energy availability (EA) was calculated as energy intake minus exercise energy expenditure, relative to fat-free mass (FFM). Skinfold thickness and blood metabolic and reproductive hormones were measured prestudy and poststudy. Statistical significance was defined as P ≤ .05. Results: Body mass (P = .11) or skinfold thickness (P = .75) did not change across time, despite alternate-day low EA (14 [9] vs 57 [10] kcal·kg−1 FFM·d−1, race vs rest days, respectively; P < .001). Cyclists with extremely low EA on race days (<10 kcal·kg−1 FFM·d−1; n = 2) experienced a trend toward decreased testosterone (−14%) and insulin-like growth factor 1 (−25%), despite being high EA (>46 kcal·kg−1 FFM·d−1) on days between. CHO intakes were significantly higher on race versus rest days (10.7 [1.3] vs 6.4 [0.8] g·kg−1·d−1, respectively; P < .001). The cyclists reached contemporary prerace fueling targets (3.4 [0.7] g·kg−1·3 h−1 CHO; P = .24), while the execution of CHO guidelines during race (51 [9] g·h−1; P = .048) and within acute (1.6 [0.5] g·kg−1·3 h−1; P = .002) and prolonged (7.4 [1.0] g·kg−1·24 h−1; P = .002) postrace recovery was poor. Conclusions: The authors are the first to report the day-by-day periodization of energy and CHO in a small sample of professional cyclists. They also examined the logistics of conducting a field study under stressful conditions in which major cooperation from the subjects and team management is needed. Their commentary around these challenges and possible solutions is a major novelty of the article.

Energetic Demands and Nutritional Strategies of Elite Cross-Country Skiers During Tour de Ski: A Narrative Review

“…While the time-course of changes as a result of LEA remains somewhat unknown and is likely to vary between various body systems, laboratory studies have shown impairments in as little as 4-5 days [45]. On the contrary, a recent report in professional male cyclists showed that very brief (< 24 h) exposures to extreme LEA (< 15 kcal/kg FFM/day) over an 8-day single-day racing period did not impair sex and metabolic hormone concentrations when alternated with days of > 45 kcal/kg FFM/day EA [32]. While the (male) endocrine system might be more resilient to acute and brief changes in EA, emerging evidence suggests that brief periods of LEA can impair sports performance indirectly as a result of decreased glycogen stores [40] and increased risk for illness [16], which will have residual effects beyond the success during the TDS.…”

“…Several reports exist on total daily energy expenditure in other endurance sports such as road cycling, These studies report total daily energy expenditures of up to 6071 and 7815 kcal/day in male cyclists during an average stage and a mountain stage of a cycling grand tour [60], respectively; meanwhile race energy expenditures of up to 5184 kcal were reported in male cyclists during single-day classic [32]. On the contrary, few studies have attempted to quantify energy expenditure and EI in elite XC skiers.…”

“…Taken together, while brief periods of LEA across the TDS may be inevitable and harmless [32], residual effects are likely to have implications for the elite XC skier who faces the challenge of maintaining optimal health and performance during and following TDS. Therefore, XC skiers are encouraged to avoid extreme LEA during the TDS and aim to maintain an EA that averages optimal levels over the period of the TDS to support health and performance during and beyond the tour (Table 2).…”

“…In addition, dietary fats are an energy-dense option to increase energy intake during intense training and competition periods, thus assisting in maintaining optimal EA. For example, professional male cyclists participating in single-day racing with daily EE of ~ 5184 kcal reported consuming up to 3.3 g/kg/day fat [32]. Finally, adequate fat intake is obviously an important component of a healthy diet of the XC skier, where effects are seen in fat-soluble vitamin metabolism and immune function [81].…”

Risk of Low Energy Availability in National and International Level Paralympic Athletes: An Exploratory Investigation

“…Research has suggested that short-term perturbations in EA do not appear to have as severe an impact on male athletes compared to female athletes [7,33]. However, recent research has suggested that extremely low EA, or even within day periods of LEA, can still result in measurable disturbances in hormone levels in male athletes after only eight days of intermittent LEA [34].…”