Effectiveness of Chocolate Milk in Recovery Among Highly Trained Kayakers: A Metabolic and Inflammatory Perspectives

Kayaking, as an endurance discipline, is associated with high energy expenditure and the need to optimize metabolic and hormonal processes in order to maximize efficiency and effective regeneration. Intense physical effort leads to significant changes in muscle metabolism and triggers an inflammatory response in the body. Such large loads require precise monitoring of energy balance and effective regeneration strategies. In the context of such intensive activity, monitoring biochemical indicators becomes crucial. They will allow for the assessment of the degree of fatigue and the course of regeneration processes. As part of the project, key metabolic and inflammatory indicators will be analyzed, such as glucose, glycogen and insulin levels, which will allow for the assessment of the efficiency of energy resource management. In addition, muscle damage indicators will be monitored, such as creatine kinase (CK) and interleukin 6 (IL-6), which will allow for the assessment of fatigue and regeneration processes in athletes.

Acid-base balance, a crucial factor in buffering lactic acid and oxygen transport to muscles, will be analyzed via blood gasometry (ABG). Lactic acid (LA) levels will also be monitored as a key fatigue indicator. Blood morphology analysis will complement the study, assessing the impact of intense exercise and recovery strategies on the hematopoietic and immune systems.

Chocolate milk is increasingly recognized as an effective recovery drink due to its optimal carbohydrate-to-protein ratio (approximately 3:1 or 4:1), promoting rapid glycogen replenishment and muscle fiber repair. Studies suggest that post-exercise chocolate milk consumption may be as effective, or even superior, to commercial sports drinks, particularly in endurance recovery. Additionally, chocolate milk provides high-quality milk protein, electrolytes (calcium, potassium, sodium), and lipids, supporting hydration homeostasis and reducing oxidative stress post-exercise. This combination may limit muscle damage, reduce inflammation (lower CK and IL-6 levels), and improve acid-base balance, making chocolate milk a viable nutritional strategy for endurance athletes.

This study aims to evaluate the effectiveness of chocolate milk in kayakers' recovery by analyzing metabolic, inflammatory, and hematological markers, thus determining its potential role in optimizing endurance sports nutrition strategies.

Changes in glucose, glycogen, insulin, CK, IL-6, grhelin, leptin, peptide YY, peripheral blood morphology, and blood gas parameters will be analyzed to better understand recovery and adaptation mechanisms influenced by chocolate milk consumption. Also, the project results may provide a basis for further research on the role of appetite hormones in sports recovery, which is a relatively new area of research in sports dietetics, and have a significant impact on new strategies to support athletes' performance.

Methods This study will examine chocolate milk's effectiveness in 30 elite kayakers (both sexes), split into experimental (n=15, chocolate milk) and control (n=15, water) groups. Blood samples (capillary and venous) will be collected at three time points: before exercise, immediately after exercise, and 1 hour post-consumption.

• Experimental group - up to 30 minutes after the erometer test, consumes 400 ml of chocolate milk.

Control group - up to 30 minutes after the erometer test, consumes 400 ml of water.

• Exercise test: During the preparatory period (April/May), participants will perform an intensive exercise test on a kayak ergometer (Dansprint PRO, Denmark), consisting of covering a distance of 1000 meters in the shortest time possible. The kayak ergometer test will be performed under medical supervision.

• Before the exercise test, a non-invasive anthropometric analysis will be performed using the TANITA MC-780MA body composition analyzer (Tokyo, Japan), to determine body composition: percentage of body fat, body fat mass, lean tissue mass, muscle mass, water and body mass index (BMI).
• Before the ergometer test, a nutrition analysis will be performed using the food diary method.
• Before the exercise test, a meal will be served containing a standardized amount of kcal, protein, fat, carbohydrates and fiber, calculated per kg of the athlete's body weight, in accordance with the nutrition standards for the Polish population edited by Mirosław Jarosz and the recommendations of the International Society of Sports Nutrition.
• During the test, measurements will be taken: travel time, average power, heart rate.

The results will determine whether chocolate milk accelerates energy replenishment, reduces muscle damage, and decreases inflammation compared to water consumption. This research will contribute to optimizing endurance sports nutrition strategies and serve as a basis for further studies on recovery methods.

Inclusion criteria

• Lack of consent for blood sampling,
• injuries, health issues,
• anti-inflammatory drugs,
• performance-enhancing substances,
• supplements within the last 3 months before the start of the study.

Exclusion criteria

• consent to participate in the study,
• regular training regimen,
• current medical examinations,
• no health contraindications.