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Int J Sports Physiol Perform. 2019 Mar 12:1-35. doi: 10.1123/ijspp.2018-0842. [Epub ahead of print]

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

Author information

1
1 Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia.
2
2 Sports Nutrition, Australian Institute of Sport, Canberra, Australia.
3
3 Mitchelton-Scott (WorldTour Team), UCI, Adelaide, SA, Australia.
4
4 Aspetar Sports Medicine & Orthopaedic Hospital, Doha, Qatar.
5
5 Nottingham Trent University, Nottingham, United Kingdom.

Abstract

PURPOSE::

To assess energy and carbohydrate availability and changes in blood hormones in 6 professional male cyclists over multiple single-day races.

METHODS::

We collected weighed food records, powermeter data and morning body mass across 8 days. Carbohydrate intakes were compared to contemporary guidelines. Energy availability (EA) was calculated as energy intake minus exercise energy expenditure, relative to fat-free mas (FFM). Skinfold thickness and blood metabolic and reproductive hormones were measured pre- and post-study. Statistical significance was defined as p≤0.05.

RESULTS.:

BM (p=0.11) or skinfold thickness (p=0.75) did not change across time, despite alternate-day low EA (14±9 vs 57±10 kcal·kg FFM·d-1, race vs rest days, respectively; p<0.001). Cyclists with extremely low EA on race days (<10 kcal·kg FFM·d-1; n=2) experienced a trend towards decreased testosterone (-14%) and insulin-like growth-factor-1 (-25%), despite high EA (>46 kcal·kg FFM·d-1) on days in-between. Carbohydrate intakes were significantly higher on race vs rest days (10.7±1.3 vs 6.4±0.8 g·kg·d-1, respectively;p<0.001). The cyclists reached contemporary pre-race fueling targets (3.4±0.7 g·kg·3h-1 carbohydrates; p=0.24), while the execution of CHO guidelines during race (51±9 g·h-1; p=0.048) and within acute (1.6±0.5 g·kg·3h-1; p=0.002) and prolonged (7.4±1.0 g·kg·24h-1; p=0.002) post-race recovery was poor.

CONCLUSIONS::

We are the first to report day-by-day periodization of energy and carbohydrate in a small sample of professional cyclists. We have also examined the logistics of conducting a field study under stressful conditions in which major cooperation of subjects and team management is needed. Our commentary around these challenges and possible solutions is a major novelty of the paper.

KEYWORDS:

energy availability; hormones; nutrition periodization; professional cycling; single-day racing

PMID:
30860404
DOI:
10.1123/ijspp.2018-0842

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