Reductions in training load and dietary carbohydrates help restore health and improve performance in an Ironman triathlete

While most endurance athletes and coaches recommend higher training loads and high-carbohydrate low-fat diets, some studies report benefits of lower intensity training for performance improvements and a low-carbohydrate high-fat eating plan. We present the case of a 38-year-old female professional/elite Ironman triathlete who presented with decreased performances, alongside severe gastrointestinal distress, excess fatigue, and severe daytime hunger. Training load was reduced from 30 to 18 h before a gradual increase to 24 h. Dietary recommendations included reducing carbohydrate and increasing dietary fat intake. Over a six-week period, daily carbohydrate content was gradually decreased from 73% (475 g) to 12% (78 g) of total calories, while fat content increased from 14% (40 g) to 75% (217 g), and protein levels remained constant at 13% (85 g). Within two months, the athlete reported increased perception of daily energy during and between training sessions, less perceived hunger and fatigue, and reduced need for daytime naps. Cycling power output increased by 20 W and run pace increased (12–15 s km−1) at the same training heart rate (141 beat min−1), and with the exception of water, nutrition was no longer required during long duration training (∼4 h). Race calories consumed were reduced from ∼400 kcal h−1 in previous years to ∼175, 145, and 130 kcal h−1 over the course of the next three Ironman events. Signs and symptoms of gastrointestinal stress ceased to occur, and two of three races were personal best times, with the final event completed in 8 h 52 min. We conclude that reducing training load, and dietary carbohydrates and increasing dietary fat, markedly improved a variety of health functions, reduced exogenous nutrient requirements during training and racing, and increased performance in an elite triathlete.

Hyperthermic Fatigue Precedes a Rapid Reduction in Serum Sodium in an Ironman Triathlete: A Case Report

Purpose:To monitor the hydration, core temperature, and speed (pace) of a triathlete performing an Ironman triathlon.Methods:A 35-year-old experienced male triathlete participated in the Western Australian Ironman triathlon on December 1, 2006. The participant was monitored for blood Na+ concentration before the race (PRE), at the transitions (T1 and T2), halfway through the run (R21), and after the race (POST; 2hPOST). Core body temperature (T ; pill telemetry) was recorded continuously, and running speed (s3 stride sensor) was measured during the run.Results:The participant completed the race in 11 h 38 min, in hot conditions (26.6 ± 5.8°C; 42 ± 19% rel. humidity). His Tc increased from 37.0 to 38.6°C during the 57-min swim, and averaged 38.4°C during the 335-min bike (33.5 km·h-1). After running at 12.4 km·h-1 for 50 min in the heat (33.1°C), T increased to 39.4°C, before slowing to 10.0 km·h-1 for 20 min. T decreased to 38.9°C until he experienced severe leg cramps, after which speed diminished to 6 km·h-1 and T fell to 38.0°C. The athlete’s blood Na+ was constant from PRE to T2 (139-140 mEq·L-1, but fell to 131 mEq·L-1 at R21, 133 mEq·L-1 at POST, and 128 mEq·L-1at 2hPOST The athlete consumed 9.25 L of fuid from PRE to T2, 6.25 L from T2 to POST, and lost 2% of his body mass, indicating sweat losses greater than 15.5 L.Conclusion:This athlete slowed during the run phase following attainment of a critically high T and experienced an unusually rapid reduction in blood Na+ that preceded cramping, despite presenting with signs of dehydration.