For athletes with T1D, the primary aim of the recovery period is the restoration and replenishment of glycogen stores; carbohydrate absorption in the gut and glucose uptake in the muscles are the primary limiting factors. An additional challenge is the requirement to maintain a blood glucose concentration between 4 and 10 mmol/L.
To maximize recovery, athletes must consider nutritional strategies to maximize glycogen resynthesis and muscle protein synthesis, muscle damage repair, and skeletal muscle reconditioning, as well as a positive muscle protein balance. Dr Stettler and colleagues outlined several techniques to achieve these goals, as summarized below.
Glucose check: Glucose levels should be evaluated immediately after exercise and checked at regular 15-minute intervals with either continuous glucose monitoring or flash glucose monitoring due to an increased risk of dysglycemia. Providers can suggest that patients set alarms to help create this routine.
Because there is an elevated risk of overnight hypoglycemia, a continuous glucose monitor alarm should be set at 4.4 mmol/L. Athletes using flash glucose monitoring should perform at least 1 scan during the night.
Insulin adjustments: Insulin adjustments should be individualized based on the type, intensity, and timing of exercise. Regardless of these factors, the magnitude of increased insulin sensitivity can be high following exercise, leading to a substantial increase in postexercise hypoglycemia risks.
For athletes using multiple daily insulin injections, providers should consider reducing the pre-exercise insulin dose, as well as the first basal insulin dose during the recovery period and the bolus dose with the recovery meal.
For athletes using subcutaneous insulin infusions, basal insulin should be reduced 60 to 90 minutes before beginning exercise. Pump suspension should be limited to a maximum of 45 to 60 minutes, and the bolus dose can be reduced by 20% to 50% at the first recovery meal; similar reductions in basal insulin should be made.
Carbohydrate intake: Carbohydrate intake should begin when the glucose concentration is less than 8.0 mmol/L. If rapid recovery is the patient’s objective and peak performance is required within a 24-hour period, individuals should consume 1.0 g/kg/h to 1.3 g/kg/h of carbohydrates for the first 4 hours of recovery, followed by food every 30 minutes thereafter.
When enhancing the training stimulus or an adaptive response is the goal, low carbohydrate availability may be achieved deliberately by reducing total carbohydrate intake or by manipulating carbohydrate intake in relation to training sessions. Data supporting this method are scarce, however, and the consensus authors do not recommend a low-carbohydrate diet to enhance exercise performance.
Using multiple transportable carbohydrates such as fructose in combination with glucose can promote faster liver glycogen repletion. However, fructose alone cannot be used to immediately treat low blood glucose, and fructose and glucose coingestion requires a lower insulin dose than glucose alone.
Protein intake: Daily recommended protein intake for endurance athletes is 1.6 g/kg/d to 1.8 g/kg/d. The addition of protein to carbohydrates immediately after exercise can increase the speed of recovery.
Hydration: Athletes should remain aware of the effects associated with drinks that contain high amounts of carbohydrates and how these drinks will affect blood glucose concentration. If blood glucose concentration is greater than 10.0 mmol/L, hydration should be achieved through carbohydrate-free drinks.
Dietary sodium and sodium chloride can also be used to help athletes retain ingested fluids.
Environmental conditions such as heat and humidity should be considered when hydrating. Consuming excessive alcohol during the recovery period is discouraged and is associated with an increased risk of hypoglycemia.
Caffeine: A dose of 3 mg/kg of caffeine (200 to 300 mg) may reduce hypoglycemia risk during and after exercise, although large amounts of caffeine consumed later in the day should be avoided due to negative effects on sleep.
Cool down: If blood glucose concentration is >10.0 mmol/L during the last 10 minutes of exercise, athletes should consider a prolonged low-intensity cool down. If blood glucose concentration is 5 to 10 mmol/L during the same period, the length of the cool down should be reduced.
“A wide variation in training and nutrition plans, insulin requirements, and experience an individual has with managing their glycemia in different situations strongly suggest that there will never be a one size fits all set of guidelines that can be applied to every athlete with [T1D],” the authors wrote. “What is consistent between individuals, however, is the large number of decisions that can influence glucose management and general health.”
To aid in this management, athletes can turn to the many technologies available to provide decision support tools that are easy to use and adjustable to individual needs.
Rapid developments in continuous glucose monitoring sensors, smart devices, wearables, and closed loop systems should ideally require less user input. An increase in accurate, reliable continuous glucose monitoring technology in particular has “greatly improved” the understanding of glycemic responses to exercise, including during nocturnal periods.
Next-generation closed-loop systems are also being investigated. These systems integrate signals such as heart rate, skin conductance, ventilation rate, and body temperature, in addition to hormones, to increase a person’s time in the target glycemic range during and after exercise.
Review limitations include the lack of published research on individuals with T1D during the postexercise period, as well as a lack of research specific to women.
“Regardless of the athlete’s sport or competition level, it is clear that many different behaviors will have an effect on short-term and long-term recovery, and thus affect the subsequent performance, training adaptation, and time in the target glycemic range,” the researchers concluded. “Athletes with [T1D] should always prioritize blood glucose management, which is essential for overall health and to optimize recovery.”
Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, nutrition, and/or device companies. Please see the original reference for a full list of disclosures.
Scott SN, Fontana FY, Cocks M, et al; Study of Integrative Biology of Exercise in Diabetes. Post-exercise recovery for the endurance athlete with type 1 diabetes: a consensus statement. Lancet Diabetes Endocrinol. 2021;9(5):304-317. doi:10.1016/S2213-8587(21)00054-1