The Truth About Antioxidants And Exercise: Help Or Hindrance?

This article discusses when to take antioxidants to maximize the effects of exercise.

Many people take antioxidants to reduce the impact of free radicals linked to chronic diseases. They often combine them with exercise to maintain good health.

But is there an ideal time to take these supplements? This article uncovers the science behind timing and its effects on your health and fitness.

Introduction

The Role of Exercise-Generated Free Radicals in Health and Adaptation

Reactive Oxygen Species (ROS) vs. Free Radicals: Know the Difference

Reactive oxygen species (ROS) and free radicals are closely related but distinct concepts in oxidative biology.

Free radicals are molecules containing unpaired electrons, making them highly reactive.

Reactive oxygen species (ROS) is a broader term. It includes free radicals like superoxide (O2-) and hydroxyl radicals (OH•). It also encompasses non-radical oxygen derivatives, including hydrogen peroxide (H2O2) and singlet oxygen.

While all free radicals are a subset of ROS, not all ROS are free radicals.

For simplicity’s sake, we will consistently use the term ROS in this article. This is because it includes both free radicals and non-radical oxidants. This ensures clarity while maintaining scientific accuracy.

Exercise, especially vigorous physical activity, significantly increases oxygen consumption. This heightened metabolic demand leads to the generation of ROS, commonly referred to as free radicals. These molecules are often linked to oxidative stress and cellular damage.

However, they play a critical role in physiological adaptations, which enhance overall health and fitness.

While ROS plays a crucial role in exercise adaptation, their effects are not always beneficial. When ROS levels become excessive, they contribute to cellular damage. If these levels persist for prolonged periods, they lead to the progression of chronic diseases.

Understanding the balance between beneficial and harmful ROS is key to optimizing health and preventing long-term complications.

Link Between Free Radicals and Chronic Diseases

While moderate ROS levels serve beneficial roles in adaptation, excessive and chronic oxidative stress contributes to numerous diseases, including:

1. Cardiovascular Disease: Excess ROS can oxidize LDL cholesterol. This leads to plaque formation and arterial stiffness. It increases the risk of heart attacks and strokes.
2. Diabetes and Insulin Resistance: Chronic oxidative stress damages pancreatic beta cells, reducing insulin production and contributing to insulin resistance.
3. Neurodegenerative Disorders: Excessive ROS contributes to neuron damage in diseases like Alzheimer’s and Parkinson’s by promoting inflammation and protein misfolding.
4. Cancer: Persistent oxidative damage to DNA increases the risk of mutation and cancer development.
5. Aging and Cellular Damage: Long-term ROS exposure accelerates aging. It damages lipids, proteins, and DNA. This leads to cell dysfunction and decline.

While chronic oxidative stress is linked to disease progression, ROS are not inherently harmful.

Exercise generates ROS in a controlled manner, often leading to beneficial adaptations. Understanding how vigorous exercise influences ROS production helps in two ways. It helps distinguish when these molecules contribute to fitness gains and when they become excessive and detrimental.

How Vigorous Exercise Generates Free Radicals

During intense exercise, several processes contribute to the increased production of ROS:

1. Mitochondrial Energy Production: The mitochondria is the primary source of ROS during exercise. As oxygen is utilized for ATP generation, a small percentage leaks from the electron transport chain, forming superoxide radicals.
2. Increased Oxygen Consumption: Exercise increases oxygen uptake by up to 20 times in active muscles. In specific fibers, oxygen uptake rises over 100 times. This leads to a proportional rise in ROS production.
3. Inflammatory Responses: High-intensity workouts cause minor muscle damage, which triggers an immune response involving neutrophils and macrophages. These cells generate ROS as part of their function.
4. Mechanical Stress and Shear Forces: Muscles repeatedly contract and relax. This induces ROS formation due to mechanical stress. Increased blood flow also contributes to this, especially in endurance and resistance training.

The Benefits of Exercise-Induced ROS

While excessive ROS levels can lead to cellular damage, moderate increases due to exercise have significant physiological benefits. Some of these include:

1. Cellular Adaptation and Mitochondrial Biogenesis

• ROS act as signaling molecules that stimulate the production of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). Both enhance mitochondrial biogenesis and improve energy efficiency in muscles.
• This adaptation increases endurance, improves fat metabolism, and enhances overall athletic performance.

2. Improved Antioxidant Defense Systems

• Exercise promotes the upregulation of the body’s natural antioxidant systems, including superoxide dismutase (SOD), catalase, and glutathione peroxidase.
• Over time, the body becomes more efficient at neutralizing oxidative stress. This reduces the risk of chronic diseases like diabetes, cardiovascular disease, and neurodegenerative disorders.

3. Enhanced Insulin Sensitivity and Glucose Regulation

• ROS generated during exercise help trigger signaling pathways like AMPK (AMP-activated protein kinase), which enhances glucose uptake by muscle cells.
• This reduces blood sugar levels and improves insulin sensitivity, benefiting those with metabolic disorders.

4. Hormesis and Stress Adaptation

• Hormesis is a biological principle where exposure to mild stressors (like ROS) enhances resilience to greater stress in the future.
• Regular exercise-induced ROS exposure strengthens cells against oxidative stress and inflammation, reducing the risk of age-related diseases.

5. Cardiovascular Benefits

• ROS help form nitric oxide (NO), a vasodilator that improves blood flow and oxygen delivery to tissues.
• This adaptation lowers blood pressure and enhances overall cardiovascular function.

The Duration of Exercise-Generated ROS in the Body

ROS generated during exercise typically remain in the body for minutes to a few hours post-exercise. Their duration depends on intensity, individual antioxidant capacity, and recovery strategies.

The body neutralizes these radicals through its own antioxidant systems and dietary sources.

However, if oxidative stress remains unbalanced due to inadequate recovery, prolonged inflammation and cellular damage occur.

If someone can produce too much ROS during exercise, what can be done to prevent it? Should I just take antioxidants right after exercise?

How Do You Prevent Excessive Production of ROS During Exercise?

Following the target heart rate (THR) can help prevent excessive production of reactive oxygen species (ROS) during exercise. However, it’s not the only factor.

Here’s how you can control ROS levels while still benefiting from exercise-induced oxidative stress:

1. Exercise at an Optimal Intensity (Target Heart Rate)

• High-intensity or prolonged exercise produces excessive ROS, leading to oxidative stress and potential tissue damage.
• Staying within moderate intensity (50–70% of max heart rate) can generate beneficial ROS levels without overwhelming the body’s antioxidant defenses.
• Formula to calculate THR: Target HR=(220−age)×(0.5 to 0.7)
  • If you’re 40 years old, your THR range for moderate exercise is 90–126 bpm.

Below is a Target Heart Rate Calculator. Enter your age so you will know your optimal exercise intensity.

Target Heart Rate Calculator

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2. Gradual Progression in Training

• Avoid sudden jumps in exercise intensity or volume, which spike ROS levels.
• Incorporate a gradual warm-up and cool-down to help the body adjust and clear excess free radicals.
• The ideal warm-up before moderate to vigorous exercise is 5 to 10 minutes of light aerobic activity (e.g., brisk walking or dynamic stretching) to gradually increase heart rate, blood flow, and muscle flexibility.
• After exercise, a cool-down of 5 to 10 minutes with light movement and static stretching helps gradually lower the heart rate. It prevents dizziness and reduces muscle stiffness. Both warm-up and cool-down phases enhance performance and aid in recovery.

3. Ensure Proper Recovery and Rest

• Overtraining leads to chronic oxidative stress. Recovery days allow antioxidant systems to rebalance.
• Prioritize sleep, as poor sleep increases oxidative stress and inflammation.
• For moderate-intensity exercise, it’s recommended to have at least one rest or low-intensity recovery day per week. This allows muscles and the nervous system to recover.
• For vigorous exercise or strength training, taking 48 hours between training the same muscle groups is ideal. This helps prevent overtraining and injury.
• Active recovery, like light walking or stretching, can be incorporated on rest days to promote circulation and reduce soreness.

4. Optimize Nutrition for Natural Antioxidants

• Instead of high-dose antioxidant supplements (which can blunt exercise adaptations), consume whole-food antioxidants:
  • Fruits & vegetables: Berries, spinach, kale, tomatoes, carrots
  • Healthy fats: Nuts, seeds, olive oil, avocado
  • Polyphenol-rich foods: Green tea, dark chocolate, turmeric

5. Stay Hydrated

• Dehydration increases oxidative stress and impairs the body’s ability to neutralize free radicals.
• Drink enough water before, during, and after exercise—especially in hot environments.

6. Avoid Over-Reliance on High-Dose Antioxidant Supplements

• As discussed, immediately taking high-dose vitamin C or E post-exercise can interfere with the beneficial adaptations of ROS.
• If needed, take low-to-moderate doses and space them out several hours after exercise.

7. Incorporate Active Recovery and Low-Impact Activities

• Light exercises like walking, yoga, or swimming help flush out oxidative stress without generating excess ROS.

Bottom Line

Staying within your target heart rate can help manage ROS production. However, balancing exercise intensity, recovery, and nutrition is key to preventing excessive oxidative stress while still benefiting from the positive effects of ROS.

Is There Any Benefit in Taking Antioxidant Supplements Before Exercising?

Taking antioxidant supplements before exercise has both potential benefits. It also has drawbacks. These depend on the type of exercise and the individual’s health status. Here’s what the science says:

Potential Benefits of Taking Antioxidants Before Exercise

1. Reduced Oxidative Stress & Muscle Damage
   • Some studies suggest that pre-exercise antioxidants like vitamin C, vitamin E, and N-acetylcysteine (NAC) can help. They reduce muscle damage and inflammation caused by intense exercise. These are beneficial for elite athletes or individuals prone to muscle soreness.
2. Improved Endurance in Some Cases
   • Certain antioxidants, like Coenzyme Q10 (CoQ10) and astaxanthin, enhance mitochondrial function. They can improve endurance performance, particularly in endurance sports like long-distance running or cycling.
3. Protection Against Air Pollutants
   • For athletes exercising in highly polluted environments, antioxidants (e.g., vitamin C, vitamin E, and polyphenols) reduce airway inflammation and oxidative damage.
4. Support for People with Chronic Conditions
   • Those with chronic diseases (e.g., cardiovascular disease, diabetes, or COPD) benefit from antioxidants before exercise to mitigate excessive oxidative stress and improve recovery.

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Potential Drawbacks of Taking Antioxidants Before Exercise

1. Blunted Exercise Adaptations
   • Antioxidants, particularly high-dose vitamin C (≥500 mg) and vitamin E (≥400 IU), may neutralize the ROS needed for exercise-induced adaptations.
   • This can impair mitochondrial biogenesis, muscle growth, and endurance improvements.
2. Reduced Insulin Sensitivity Benefits
   • Exercise naturally improves insulin sensitivity. However, some studies suggest that high-dose antioxidants taken pre-exercise may blunt this effect, reducing its metabolic benefits.
3. Possible Decrease in Performance for Strength Training
   • Some research indicates that NAC can reduce muscle fatigue. But, it may also suppress natural muscle adaptations by interfering with ROS-driven signaling pathways.

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Best Practices: When to Take Antioxidants for Exercise

• For muscle recovery: Low-to-moderate doses of antioxidants (like polyphenols or CoQ10) before exercise may help, but avoid high doses.
• For endurance benefits: CoQ10 and astaxanthin before workouts may aid performance without harming adaptations.
• For strength training or metabolic health: Avoid high-dose vitamin C, vitamin E, or NAC right before or after workouts—instead, take them several hours later or at night.

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Conclusion

If your goal is long-term fitness adaptations, mitochondrial health, and insulin sensitivity, avoid high-dose antioxidants before exercise.

If your goal is faster recovery from excessive training or injury, antioxidants may help—time them several hours later or before bed.

Timing and dosage are key!

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Image credits:

Mitochondrion By Mariana Ruiz Villarreal LadyofHats – Public Domain, https://commons.wikimedia.org/w/index.php?curid=6195050

References:

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