Seasonal changes in energy intake and emerging indicators of energy availability in young elite Nordic skiers.

Energy intake increased by 25% and carbohydrate intake increased by 14.5% for both sexes during the 24-week study period.

• Both male and female Nordic skiers showed the same relative increases in energy and CHO intake.
• Despite the 25% increase in energy intake, this was insufficient relative to the concurrent increases in training volume.
• The study involved 30 female and 30 male young elite Norwegian Nordic skiers in a 24-week controlled clinical trial.
• The study covered the transition from the competitive season to preparation for the subsequent season (off-season).

Training volume increased substantially during the study period, with female athletes increasing by 41% and male athletes increasing by 83%.

• The increase in training volume was substantially larger than the concurrent increase in energy intake (25%) for both sexes.
• The large discrepancy between energy intake increases and exercise volume increases suggests athletes were unable to sufficiently match nutritional intake to training demands.
• Weekly training hours were tracked as a key variable alongside dietary intake throughout the 24-week period.
• Male athletes showed a particularly large training volume increase (83%) compared to female athletes (41%).

Positive correlations were found between higher BMD, bone markers, RMR, and lean mass and negative correlations between VAT and REDs symptoms.

• Blood variables measured included vitamin D, total osteocalcin (tOC), and the PINP1/CTX1 ratio as bone markers.
• Resting metabolic rate (RMR), bone mineral density (BMD), lean body mass (LM), visceral adipose tissue (VAT), and body fat percentage (BF%) were assessed.
• VAT was specifically correlated with RMR and bone markers.
• These correlations underscore the clinical consequences of insufficient energy intake.

Lean body mass emerged as a key predictor for health variables, explaining variability across multiple REDs markers.

• LM was identified as a key predictor among the variables assessed in the study.
• LM explained variability across multiple REDs markers simultaneously.
• This finding highlights the importance of monitoring lean mass as part of REDs assessment in Nordic skiers.
• The result suggests that focusing on low body mass and body fat percentage without sufficient nutritional knowledge may have adverse health consequences.

VAT, total osteocalcin (tOC), and the P1NP/CTX-ratio were identified as promising indicators for monitoring dietary interventions in individuals with REDs.

• These three markers were highlighted as promising for monitoring nutritional interventions specifically in REDs contexts.
• The P1NP/CTX-ratio represents the ratio of procollagen type 1 N-terminal propeptide to cross-linked C-telopeptide type 1-collagen, reflecting bone turnover balance.
• The authors recommend these markers be considered in future research on REDs treatment strategies.
• VAT showed correlations with both RMR and bone markers, supporting its utility as a monitoring tool.

Nordic skiing may be particularly susceptible to low energy availability (LEA) and relative energy deficiency in sport (REDs) due to its high energy demands.

• The study was designed to examine nutritional practices and physical symptoms associated with REDs among young elite Norwegian Nordic skiers.
• The emphasis was placed on energy and carbohydrate intake during the transition from competitive season to preparation period.
• The study involved both female (n=30) and male (n=30) elite Nordic skiers.
• The correlations between energy intake and BMD, RMR, VAT, and HR were noted to underscore the clinical consequences of insufficient energy intake.

Calcium intake was monitored as a dietary variable alongside carbohydrate and protein intake throughout the study.

• Daily dietary intake variables included carbohydrates (CHO), protein, and calcium (Ca) intake.
• Calcium is relevant to bone health, which is a key concern in REDs.
• These dietary variables were tracked over the full 24-week controlled clinical trial period.
• Dietary intake data were combined with blood biomarker and body composition assessments.