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Persistent Muscle Soreness can be a Sign of Overtraining
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Persistent Muscle Soreness can be a Sign of Overtraining

By Byron Fergerson, M.D. Chief Science Advisor to Freak Shake

Persistent Muscle Soreness can be a Sign of Overtraining

Endurance athletes are famously stoic. While most endurance sports don’t require explosiveness to tackle, leap, or move heavy things, they are still exceptionally demanding on muscle. Because endurance training doesn’t typically emphasize a lot of heavy resistance training and power, endurance athletes experiencing persistent muscle soreness often ignore this  symptom of over-exertion and stress.

Distance sports like running, cycling, Nordic skiing, and high intensity endurance like swimming and rowing require stamina, strength, and resilience. Highly repetitive, full body endurance exercise generates a significant cumulative amount of stress on muscles and can lead to muscle breakdown. The bottom line is if you are experiencing persistent delayed onset muscle soreness (DOMS) after endurance workouts, you may be overtraining. It’s important to take the time to fully recover and allow muscles to heal.

In this article we'll explore our physiological recovery mechanisms, and discuss the science of plant-based micronutrients called flavonoids which have been demonstrated to help accelerate recovery and help endurance athletes manage the risks of over-exertion by optimizing their recovery.  

 Among elite endurance athletes, runners are at the highest risk of Overtraining Syndrome (OTS). Adequate recovery is the only cure, but good feeding habits post workout can help accelerate recovery and improve resilience. High performance recovery drinks that help accelerate biological recovery processes can offer an edge to athletes who want peak performance when their next workout is less than 24 hours away.


Overtraining Syndrome (OTS)

To become a better endurance athlete, you need to push your body outside its comfort zone. By introducing into workouts a little more stress than your body is conditioned to tolerate, you slightly damage muscle tissue and cells. This leads to a biological response which includes inflammation around the damaged tissue that we feel as soreness. By pushing ourselves incrementally, the body rebounds stronger through adaptations that benefit muscles, organs, and even intra-cellular functions that contribute to endurance and performance.

But when we persistently over-exert over longer periods without fully recovering (think months, not days or even weeks), athletes can experience the symptoms of Overtraining Syndrome or OTS.

Distance runners have a unique penchant for exceeding their threshold for sustainable exertion over time. The likelihood of an elite runner experiencing OTS at least once in their career is 60% compared to estimates between 30-40% among elite athletes across all sports. Even for nonelite runners, one study found that 1/3 of women who run recreationally will experience these symptoms at least once during training.

Symptoms of OTS

OTS occurs when an athlete accumulates a large recovery deficit. Each day of exercise without fully recovering from yesterday’s workout, prevents the body from returning to biological equilibrium, called homeostasis. As that deficit grows, increasingly difficult symptoms can occur that can take much longer to undo.

Any runner chasing serious fitness goals can relate to overdoing it for a week and feeling sore, stiff, and fatigued. These symptoms are known as Functional Overreaching. A couple days of rest and good nutrition generally is all it takes to restore equilibrium where you can resume normal training.

However, more persistent symptoms indicating OTS may include:

  • A heavy feeling, stiffness, or muscle soreness
  • Fitness or performance levels off or declines
  • Fatigue and a general depletion of energy reserves
  • A headwind effect where training feels more labored
  • Recurring or nagging injuries
  • Elevated resting heart rate
  • Sleep interruptions and insomnia
  • Lower motivation, increased agitation, or irritability
  • Decreased self-confidence, less enjoyment from hobbies and interests and signs of depression

The Biology Behind OTS

Muscle tissue that still needs repairing because recovery was interrupted by a subsequent workout remains inflamed. Some inflammation is a necessary and beneficial biological response to the stress of exercise because it signals important healing processes that rush resources to muscle tissue in need of repair. But an accumulation of inflammation over time can become chronic and persistent. Chronic inflammation can result in more long-lasting damage to muscle, including weakening that can lead to traumatic injuries when running or exercising at a level of exertion normally tolerated.

The accumulation of stress through inadequate recovery triggers production of proinflammatory proteins called cytokines that stimulate inflammation. But as cytokines accumulate through repetitive overtraining and inadequate recovery, they can begin to impact the function of your central nervous system. At that stage, numerous vital functions including tissue repair, sleep, appetite, the endocrine system, immune system, and reproductive system can become impacted.

Inadequate recovery and overtraining is also related to inadequate fueling and replenishment. If the body is in a calorie or nutrient deficit during extended periods of strenuous training, the body may have inadequate available resources to heal itself, and it will steal those resources from other parts of the body including muscle and bone which can further compound weakening and your ability to sustain training workloads.

Muscle Breakdown and Soreness

In endurance athletes, the most common symptom of Functional Overreaching and less commonly OTS, is delayed onset muscle soreness or DOMS. Distance sports primarily engage slow-twitch muscle fibers, which are designed for endurance. These fibers are highly adapted to aerobic respiration, which means relying on oxygen to generate fuel for muscle contractions for sustained durations. However, the repetition and duration of long-distance training can cause muscle fatigue and damage to these fibers in several ways:

1) Mechanical Stress

Repetitive motion with a resistance force (resistance from the water if you swim, the pedals if you cycle, or the impact or the road if you run...) generates mechanical stress to muscle fibers, leading to micro-tears and inflammation.

2) Metabolic Stress

Prolonged exercise leads to the depletion of glycogen energy stores in muscle and liver. There is also an accumulation of metabolic byproducts like lactic acid in muscle, which contributes to muscle fatigue and soreness.

3) Oxidative Stress

Intense aerobic activity increases the production of free radicals, which can damage muscle cells and contribute to inflammation.

The Biology of Muscle Recovery

The recovery process following long bouts of endurance training is critical to help muscles repair, regenerate, and strengthen. Here’s what’s happening when muscles become damaged and inflamed from exercise stressors and begin to repair during recovery.

1) Muscle Repair and Protein Synthesis

The body repairs damaged muscle fibers through a cellular process where it fuses muscle fibers together to form new muscle protein strands or myofibrils. These repaired myofibrils increase in thickness and number to create muscle hypertrophy (growth).

2) Removal of Metabolic Byproducts

The body increases blood flow to the affected muscles to remove the cellular debris that is a metabolic byproduct of exercise. It also helps clear lactic acid from tissue, helping alleviate soreness and fatigue.

3) Replenishment of Energy Stores

Recovery involves restoring depleted glycogen stores. Consuming enough carbohydrates post-exercise is crucial to aiding this process, particularly in the 2-hour window immediately following exercise. Simple carbs like sugar are fastest absorbed and are most helpful when combined with a small amount of protein to quick start glycogen replacement and bridge the recovery period until an athlete can access more complex carbohydrates in the form of whole foods.

4) Reducing Oxidative Stress and Inflammation

We’ve discussed some of the ways that our immune system triggers an inflammatory response to repair muscle damage. Oxidative stress is one contributor to inflammation in muscle. Maintaining an adequate balance of antioxidants through good nutrition is therefore an important way to neutralize free radicals that contribute to oxidative stress and inflammation during exercise.

Our ability to tolerate increasing levels of stress is the main goal of endurance training and a predictor of performance. While some inflammation is a natural part of the recovery process, limiting excessive inflammation from overreaching and allowing enough time for full recovery are the surest ways to clear inflammation.

Micronutrient Flavonoids and Muscle Recovery

Flavonoids, a group of bioactive micronutrients found in plants like tea and cacao, have demonstrated significant potential to enhance and accelerate muscle recovery, particularly in endurance sports like long-distance running, and cycling.  Freak Shake Endurance Fuel and Grit Fuel antioxidant capsules are uniquely fortified with these naturally occurring compounds to help optimize the recovery of muscle following strenuous endurance training.

How do they work so well?

Antioxidant Effects

The flavonoids in Freak Shake products have strong antioxidant properties. They can neutralize free radicals, reducing oxidative stress and muscle damage. This antioxidant activity not only can help accelerate recovery but also helps improve muscle function post-exercise.

Promoting Blood Flow

Flavonoids like the epicatechin in Freak Shake, improve blood flow by increasing the production of nitric oxide, a vasodilator. Enhanced blood flow means more oxygen and nutrients can reach muscles, aiding in faster repair and recovery. Increased blood flow also means more rapid removal of cellular debris that is produced during exercise.

Anti-inflammatory Properties

The anti-inflammatory effects of flavonoids can help in reducing the inflammation associated with muscle repair. This can lead to a decrease in muscle soreness and improved recovery times.

Mitochondrial Function

Flavanols may improve the efficiency of mitochondria, the powerhouses of cells. Efficient mitochondrial function is crucial for endurance sports, as it enhances the body's ability to produce energy.

The Freak Shake Takeaway

Athletes can incorporate flavonoid-rich whole foods into their diets including leafy vegetables, onions, apples, berries, citrus fruit, tea and cocoa (dark chocolate – yum). However, it is often challenging to access enough complex carbohydrates and flavonoids from whole foods as a snack or meal within the two hour post-workout glycemic replacement window when the body is primed for recovery and supplementation of flavonoids can help boost recovery. Freak Shake products offer a convenient bridge to quickly start complete recovery post workout. Each serving is uniquely fortified with functional serving of natural flavonoids to help the body maximize recovery.

Our drink mixes also incorporate several other key components to maximize recovery post-workout. With over 33g of carbs per serving Freak Shake helps quick start production of glycogen stores exhausted during a bout of training. It also has over 1000mg of electrolytes to replenish what we lose in sweat and helps restore hydration. Finally, we fortify Freak Shake with a modest 12g of complete protein, which provides the building blocks to begin muscle repair and growth. This amount of protein also plays a significant role in glycogen replacement. Freak Shake’s ratio of 3:1 carbs-to-protein is in the ideal range to optimize glycogen replacement after endurance training.

If you’re a endurance athlete chasing tangible performance improvements through a daily training program, we hope you try road testing Freak Shake Endurance Fuel!


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