Whether you are experiencing pain due to arthritis, an old ACL injury, or you tweaked your knee while moving furniture last weekend, knee pain can be a debilitating barrier when it comes to any type of movement. Understanding more about the sources of knee pain, the healing process, and the role of nutrition and rehab can help you figure out the best way to properly manage knee pain.

Common causes of knee pain
Understanding the cause of your knee pain is crucial in learning how to properly manage and treat it. Three common causes of knee pain are:

• Problems within the joint or surrounding structures
  • Osteoarthritis, Rheumatoid Arthritis, Systemic Lupus Erythematosus can target large weight-bearing joints in the body, like the knee, and create specific movement and pain patterns. 
  • Issues involving the ligaments, knee cap, or meniscus can change the way the joint works while forcing other areas of your body to compensate. 
• Muscle imbalances
  • Weakness of the muscles that control the knee can cause a cascading effect on nearby muscles. Over time, this weakness becomes more profound and difficult to correct due to overcompensation by other muscles.
  • Weakened muscles in nearby joints (hip and ankle) can significantly affect the way the knee moves and absorbs weight. Interestingly, weakness in your hip stabilizers, like your glutes and core, can indirectly cause knee pain despite no history of trauma or injury to the knee itself. 
• Overtraining
  • Runners are familiar with this term, but it can also apply to anyone who does not adequately rest between workout sessions. Overtraining of one muscle group, combined with undertraining others, can lead to muscle imbalances or injury.

The healing process 
Regardless of the site and cause of injury, our bodies attempt to heal themselves through a self-regulated healing process. 

1. During the acute phase, the body immediately initiates a short-term inflammatory response that brings nutrients and other healing substances to the site of injury or infection. The acute phase begins at the time of injury and lasts up to four days.

During this stage, knee pain can be felt as a constant throbbing sensation, and your knee joint may be warm to the touch. Treatment consists of rest, ice, and elevation of the leg. Active exercise is not encouraged at this time.

2. The subacute phase usually begins about three days after the initial injury and can last up to six weeks post injury. During this period, the body begins laying down new tissue, called scar tissue, that is less elastic and flexible than the original tissue. 

In the beginning part of the subacute phase, pain may be felt with all movement and weight-bearing activity. However, towards the later part of the phase, pain is mostly felt with specific movements that directly stress the new scar tissue.

Exercises that focus on glute, hip, and core strength are critical in this stage while knee movement is still slightly limited.

3. Lastly, the chronic stage occurs as the body continues to replace the injured tissue with collagen for up to one year post injury. Pain should be minimal but may be experienced as you attempt to increase your strength and flexibility.

Be sure to exercise in a pain-free range and focus on form. Knee joint compression is greatest at 90 degrees of knee flexion, which means that you are likely to experience increased pain as you deepen your squat. There are many squat variations that can be practiced such as wall squats, bench squats from an elevated surface, and wall sits at various angles.

Supplementing with collagen: Recently, collagen has gained popularity as a common supplement for skin, bone, and joint health. Although there is limited evidence to support its ability to accelerate the healing process, supplementing your diet with protein, Vitamin A, Vitamin C, copper, and zinc will give your body the building blocks required to synthesize collagen.

Treatment for knee pain is not a one-size-fits-all approach. The best treatment for you is one that carefully considers your current stage of healing, age, previous injuries, and pain. Your nutrition can also play an important role in injury recovery and pain management, and preventative nutrition can help decrease your risk of developing chronic diseases. 

A Nutritional Approach to Knee Pain
Consider taking a holistic approach to managing knee pain by incorporating natural anti-inflammatory foods, like antioxidants, into your diet. This can accelerate recovery and decrease your risk for chronic inflammation by preventing the formation of free radical substances that are produced during recovery from intensive exercise or injury. Over time, high levels of free radicals can lead to cell damage and systemic inflammation. By adding antioxidants into your meal plan, you are breaking down free radicals in order to prevent further damage to the body's cells. 

High levels of inflammation, combined with low levels of antioxidants in the body, can cause fatigue, muscle damage, or joint pain. It also increases the risk for chronic conditions such as arthritis, certain types of cancer, Type 2 diabetes, etc. Combat this risk by incorporating these anti-inflammatory foods and holistic strategies to enhance injury recovery and prevent chronic inflammation: 

• Add some spice into life 

Garlic, turmeric, and curry have anti-inflammatory properties and can help with swelling during the initial healing process.

• Hydrate

Your body needs to maintain its blood pressure in order to transport nutrients to the site of your injury. In general, you should drink about 0.5-1 oz of water per pound of body weight (or 15-30 ml of water per .45 kg).

• Don’t cut the calories 

Decreasing calories can prolong the healing process, especially during the subacute phase which requires extra energy in order to rebuild the injured site. 

• Pack on the protein

Proteins and amino acids are the building blocks of soft tissue in our body and also aid in controlling the inflammatory response. High protein intake is essential for maintaining lean body mass and replenishing and rebuilding injured tissue.

The amount of protein recommended post-injury varies; however, various studies show that 1.5-2 g of protein per kg (or 2.2 lbs) of body weight is beneficial for injury healing and lean body mass retention. Sources of lean protein include poultry, fish, eggs, beans, legumes, nuts, protein-rich yogurt, tofu, and bone broth (high-quality protein powder can also be used, but nutrients from real, whole food are preferable).

• The vitamin and mineral heroes 

Vitamin A helps control oxidative stress caused by excessive exercise/injury and is found in sweet potatoes, carrots, tomatoes, leafy greens (kale and spinach), and broccoli. 

Vitamin C functions similarly and is found in peppers, citrus, guava, citrus, pineapple, and kiwi. 

Zinc deficiency is associated with delayed wound healing. Zinc is mostly found in meat, fish, chicken, dairy, whole grains, and beans. 

Copper is involved in the recreation of red blood cells and can be found in liver, oysters, spirulina, shiitake mushrooms, and leafy greens. 

Compounds called anthocyanins found in dark purple and blue foods, namely blueberries, eggplant, blackberries, cherries, plums, grapes, and purple potatoes, can naturally reduce inflammation, soreness, and muscle pain.

• Fitting in the fat

Fish, eggs, flaxseed, leafy greens, and walnuts are rich in Omega 3s and can also decrease your risk for chronic inflammation. 

Tips on how to exercise with knee pain
People who suffer from knee pain can understand the frustration in learning how to exercise without further aggravation of pain, discomfort, and soreness. If you struggle to figure out the best ways to exercise with knee pain, the following tips may be helpful: 

• Make sure your lower body exercises are appropriate for your level of injury, pain, and stage of healing. Reintroducing exercise following an injury should be done gradually and incrementally. Always check with a healthcare professional if you have questions or concerns. 
• Check your shoewear. Knee pain can sometimes be managed by replacing worn-down soles, adding an orthotic insert, or finding the right arch support. 
• Lastly, listen to your body and acknowledge the messages that your pain is telling you. If your knee pain is affecting your workout, then stick with open chain exercises that do not require weight-bearing through the knee joint. Exercises like clamshells, side-lying leg raises, planks, Spidermans, and stretches are great alternatives to closed chain exercises (squats, lunges, step-ups) that significantly increase compression through the knee joint. 

For more information on exercising with knee problems, check out these great articles on specific exercises for knee pain, knee exercises for runners, and ways to prevent knee problems in the future.

Did you find this article helpful? Are there strategies that you will try to incorporate? Let us know what works for you, and if you have any questions for us.

Written for Fitness Blender by Kayla C, PT, DPT
Board-Certified Neurological Clinical Specialist

and

Natalia Holguin, RDN LDN CPT 
Certified Nutrition Coach