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Some Unintended Consequences of Endurance Training
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Some Unintended Consequences of Endurance Training

Endurance training, like long-distance running or cycling, primarily relies on aerobic metabolism, meaning the body uses oxygen to generate energy. This form of exercise has numerous health benefits, but it can also have some unintended consequences on muscle and protein balance in the body, particularly if not managed correctly.

1. Energy Expenditure and Caloric Deficit:

Endurance activities burn a significant number of calories. If the energy expended during these activities is not adequately replaced through nutrition, the body may enter a caloric deficit. In a deficit, the body starts using stored energy sources, including muscle protein, for fuel.

2. Catabolic State:

Prolonged endurance training, especially without sufficient caloric intake, can lead to a catabolic state. Here, the body breaks down muscle tissue to provide energy. The hormone cortisol, which is elevated during long periods of exercise, can accelerate this process.

3. Muscle Fiber Type Adaptation:

Endurance training promotes adaptations in muscle fibers. There's a shift from fast-twitch (type II) fibers, which are larger and more powerful, to slow-twitch (type I) fibers, which are more efficient at using oxygen for energy. This shift can lead to a reduction in overall muscle size and strength.

4. Amino Acid Utilization:

During prolonged endurance exercises, the body may start using amino acids (the building blocks of proteins) as a fuel source. This process involves breaking down muscle proteins to release amino acids, which can then be converted into glucose for energy.

5. Hormonal Changes:

Endurance training can influence hormone levels in ways that affect muscle mass. For example, prolonged and intense training can reduce testosterone levels in men, which is crucial for muscle growth and maintenance.

6. Oxidative Stress and Inflammation:

Endurance exercise can increase oxidative stress and inflammation, which can lead to muscle damage and protein degradation. This is especially true if recovery periods are not adequate.

7. Reduced Protein Synthesis:

Endurance training, particularly without sufficient nutrition, can reduce muscle protein synthesis – the process by which cells build proteins. This decrease in protein synthesis, combined with an increase in protein breakdown, can lead to muscle loss.

8. Nutritional Imbalance:

Endurance athletes may focus more on carbohydrates to fuel their training, potentially neglecting protein intake. Insufficient protein consumption impairs muscle repair and growth, leading to muscle loss over time.

9. Overtraining Syndrome:

Overtraining without adequate rest and recovery can lead to muscle loss. Overtraining syndrome is characterized by fatigue, decreased performance, and increased catabolic activity, which can degrade muscle tissue. About 60% of elite runners and between 30-40% of elite athletes across all sports will experience overtraining syndrome at least once*.

10. Aging and Muscle Protein Metabolism:

Age-related changes in muscle protein metabolism can exacerbate muscle loss in endurance athletes. Older athletes might experience a blunted anabolic response to protein intake, making it harder to maintain muscle mass.

Strategies to Mitigate Muscle Loss:

Balanced Nutrition: Consuming adequate calories, with a focus on sufficient protein intake, is crucial. Protein helps in muscle repair and building, and consuming it in enough quantities can mitigate muscle loss.

Strength Training: Incorporating strength training into an endurance training program can help maintain muscle mass and strength.

Recovery and Rest: Ensuring adequate rest and recovery between training sessions helps the body repair and rebuild muscle tissues.

Periodization: Varying the intensity and volume of training can prevent overtraining and reduce the risk of muscle loss.

Supplementation: Amino acid or protein supplements may be beneficial, especially around training sessions, to support muscle protein synthesis.

Freak Shake Endurance Fuel is formulated with just enough protein to benefit endurance training.

Our goal is to help endurance athletes improve resilience, protect muscle, and accelerate recovery. How does our protein strategy help?

We start with high carbohydrates and high electrolytes to rapidly supply and replenish these resources that are rapidly exhausted in moderate to high intensity endurance training. Each serving of Freak Shake Endurance fuel contains 33g of Carbohydrates and over 1000mg of electrolytes.

Next, we fortify each serving with just enough protein to support recovery in endurance training. Very few carb and electrolyte sports drinks also incorporate an appropriate amount of protein for moderate to high intensity endurance training. Our ratio of 3:1 Carbs to Protein has been demonstrated to be within the ideal proportion for this type of conditioning exercise to maximize glycogen energy replacement.

Accompanying carbohydrates with some protein can improve recovery, especially if peak performance is desired within 24 hours after strenuous, depleting exercise. Athletes should consume a large amount of carbohydrates immediately after exercise and continue feeding ideally every 30 minutes or so for 4-6 hours. The recommended range is 1.0 - 1.5 g of Carbs per KG of body mass per hour which translates to between 75 - 115g of Carbs per hour.  But with the addition of just a modest amount of protein with in the range of 1g per 3-4g of carbs, only 0.8 g/kg/h carbohydrates are necessary to resupply muscle glycogen stores. Freak Shake’s protein fortification is within this ideal ratio to help maximize glycogen replacement.

Finally the protein in Freak Shake contains a complete amino acid profile. These are the essential building blocks of muscle that we must ingest because our bodies cannot manufacture them internally. The sooner you can supply these micronutrients to inflamed muscle cells after exercising, the quicker repair, recovery and strengthening adaptations begin to occur in that muscle.

The takeaway:  Freak Shake Endurance Fuel is not a traditional high protein supplement. It is a pre and post workout endurance fuel to supply or replenish the energy and hydration resources your body demands during moderate to high intensity endurance exercise. We incorporate a modest amount of protein to enhance recovery for athletes training strenuously and to exhaustion. We’ve designed Freak Shake to be a convenient fueling station, that can bridge an athlete to a more complete meal especially immediately following exercise.

Byron Fergerson, M.D. & David Stuart, Ph.D.are scientific advisors to Freak Shake and regularly share their expertise



Cardoos N. Overtraining syndrome. Current sports medicine reports. 2015 May 1;14(3):157-8

Raglin JS, Morgan WP. Development of a scale for use in monitoring training-induced distress in athletes. Int’l Jrnl of Sprts Medicine. 1994 Feb;15(02):84-8.

Beelen, M., Cermak, N., van Loon, LJC., Performance enhancement by carbohydrate intake during sport: effects of carbohydrates during and after high-intensity exercise. Ned Journal of Medicine. 2015:159;A7465.

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