Knee Pain, Collagen, and Proper Training

by Dr. Sam Schwartz, PT, DPT

The human body is by far the most advanced healing machine; the most complex, carefully regulated combination of systems designed specifically to maintain a steady state of health to promote longevity. Even when disturbed, the body gracefully maintains a great deal of composure and demonstrates a high degree of resiliency all the while providing only a simple stimulus of discomfort or pain to indicate any disturbance. Although this pain is highly complex in nature, it often presents at the location of injury. Makes sense, right? So let’s talk about one location of injury today specifically, the knee. And let’s break down some of the possible causes of pain, dysfunction, or disturbance in the knee as well as offer some advice on how to self-manage these injuries and sustain long-term knee health.

First, let’s talk about structure. The knee is made up of four connecting bones, the thigh bone (femur), the kneecap (patella), and the two shin bones (tibia and fibula). And then there’s the softer stuff. The muscles include the quads, hamstrings, adductors, and calf complex which provide active stability to the knee. The ligaments include the cruciate ligaments: anterior, posterior, medial, and lateral, which provide passive stability to the knee. Next, the tendons, most importantly the patellar tendon which connects the kneecap to the low leg, and the often-forgotten quad tendon which connects the quads to the kneecap. And finally, the infamous iliotibial (IT) band. But, more on all of that later. The point is, the knee is complex, and all of these pieces have to work intricately together to allow the knee to bend and straighten with ease under various conditions of stress. If even one of these structures experiences some sort of disruption, pain happens. So many structures, so little space; so let’s talk about some of the most common ailments associated with the knee.

 

Osteoarthritis – The Most Common Cause of Knee Pain

Let’s start with one of the most common causes of knee pain, osteoarthritis. Osteoarthritis (OA) of the knee is one of the most common causes of knee pain by leaps and bounds.^1,2 And no, it doesn’t just happen to the old folks; osteoarthritic changes can happen at younger ages, too. Oftentimes we see it in younger athletes who have had previous knee surgeries or other injuries impacting the surrounding structures causing a higher propensity. If you’ve had surgery before you might have heard, “you’ll likely have some arthritis in that knee at some point” from your surgeon immediately after surgery. Morbid, right? Good news, though!

Public Service Announcement: OA is not a death sentence, but instead a call to action to your body to get moving more!

Yes, you heard that right, arthritis is not a death sentence; memorize that statement, engrain it in your brain, and please, spread the word. Sorry, I digress, but it needed to be said. Anyways, OA is essentially the breakdown of cartilage and bone that occurs between the femur and the lower leg bones which result from unnecessary or inappropriate loading of those structures.^1,2 Generally, in healthy bone tissue, we see a match of bony breakdown and remodeling. But in the case of osteoarthritis, over time we see bony breakdown occurring at a faster rate than bony remodeling or deposition, essentially causing the bone to become more fragile. It is this fragility that causes our loading capacity to decrease resulting in the development of pain and discomfort when loading demands are higher for longer periods of time. Consequently, the hallmark signs of knee OA include knee pain with squatting, walking, running, and the like for longer periods of time. People also often report morning stiffness that loosens up throughout the day. These are just a few of the commonalities we often see clinically with knee OA.

Now onto self-management; self-management of OA is highly dependent upon presentation. Don’t get me wrong, some arthritic changes will benefit from surgical intervention or injections, particularly those who have struggled with knee pain for years and have failed with conservative management. But in general, I’d argue the vast majority of knee OA can be successfully managed through carefully prescribed, specific, and progressive loading of the body. And why is this? Like we discussed earlier, the body is highly resilient and will adapt under the right conditions. Physiologically speaking, the body can learn to match bony breakdown to bony deposition, remember that? That thing we talked about earlier, the whole reason why people experience OA symptoms in the first place. That’s right, under appropriate stress the body can literally start making more healthy bone tissue to better match bony breakdown in order to stabilize your joint surfaces and manage your symptoms. It’s amazing. Motion is lotion, there’s no doubt about that. Your body needs to move in order to adapt and heal, it’s just about knowing what type of movement and how much is necessary to promote positive change. So in other words, the best thing you can do to help manage your OA and/or prevent development of OA is to move!

Now let’s shift focus to some other common causes of knee pain more specific to our athletes. First off, the ever-so-popular Runner’s Knee AKA Iliotibial Band (ITB) Syndrome. ITB Syndrome is an overuse injury commonly experienced by runner’s and other athletes who increase workload too much, too fast.³ The primary complaint is pain in the outside of the knee after a heavier bout of physical activity than usual, most commonly, a run, hence, Runner’s Knee.³ Generally we see weak tight and weak glutes and thighs associated with these types of injuries. So, in terms of self-management, stretch and strengthen those areas. It’s pretty simple really. Once again, strengthening those areas requires safe, progressive, carefully prescribed loading. Yet again, motion is lotion for this injury and is key to getting runners back to peak performance as soon as possible.

 

Jumper’s Knee – Patellar Tendinopathy

How about pain just below the kneecap? Basketball players will often complain of pain with running and jumping in this region particularly after a long stretch of gameplay. It could be what’s called Jumper’s Knee AKA Patellar Tendinopathy (PT). PT is yet another overuse injury of the knee resulting from repetitive tasks such as jumping that stress the patellar tendon beyond its load tolerance capacity.^4,5 In other words, the athlete is jumping too often without having the hip and thigh strength once again to support that movement. Thus, the patellar tendon takes on too much load, develops low-level inflammation, and results in the development of pain.⁴ Self-management follows the same guidelines as ITB Syndrome, load the tendon under safe, progressive, and carefully prescribed conditions to build load tolerance and reduce discomfort. The only major difference we see in this case is that the patellar tendon generally responds well to eccentric loading, otherwise known as strengthening the thigh as the patellar tendon is lengthening such as with step-downs and with the descent phase of a traditional squat.⁵ Once again, load the body appropriately, the body adapts.

 

Pulled Muscles?

And finally, let’s talk about the ever-so-popular “pulled muscle” around the knee. Those “pulled muscles” are really just another term for a muscle strain or mini-muscle tears. Tear might seem like a harsh term, but that’s what happens with these “pulled muscles”. When someone “pulls” a muscle, it means that small regions of muscle fibers are torn or damaged, often secondary to high-impact, high-speed loading tasks.⁶ Commonly strained muscles around the knee include the quads (front of thigh), adductors (inside of thigh), and hamstrings (back of thigh).

 In my own clinical practice, I often see hamstring strains that occur during sprinting activities when the athlete contacts the ground with the heel while straightening the knee; maybe you’ve experienced a similar mechanism. This impact tends to tug just enough on the hamstring tendons to overload the muscle and tear small fibers within the muscle. Muscle strains are graded based on the severity of injury on a scale of 1-3, 1 being “mild” strain, 2 being “moderate” strain, and 3 being “severe” strain which is dependent on loss of function, motion deficits, and physiologic size of the injury.⁶ Lower-grade strains (1-2) may present with as mild of symptoms as slight discomfort at the site of injury and minimal loss of function while higher-grade strains (2-3) may present with more significant symptoms including bruising, swelling, severe discomfort at the site of injury, and 50% or more loss of function.⁶

Depending on the severity of injury, treatment varies. But in general, controlling inflammation is the primary goal, one way in which this type of injury differs from those previously discussed. New evidence suggests the best way to do so is by elevating the leg and compressing the tissue in order to push the fluid back to the heart vs. otherwise modifying the body’s natural inflammatory response with the use of ice and/or heat; a paradigm shift of sorts.⁷ So next time you are managing your own inflammation, think twice about applying heat and ice. Now after the initial inflammatory response is managed, the self-management prescription is the same as the previously discussed knee injuries; safe, controlled, carefully progressed loading of the healing muscle tissue. And again, motion is lotion.

 

Treating Knee Pain

So much can happen at the knee. So many structures to damage, so many injuries to accrue, yet still the body can adapt, heal, and thrive. Again, the body is amazing. But let’s discuss the elephant in the room. And that’s that all of these conditions heal and thrive under conditions of movement, not immobility. All of these injuries require safe, progressive, appropriate loading. It is this type of stimulus that facilitates bodily healing, that promotes body resiliency, and brings us back to optimal health. In fact, recently the British Journal of Sports Medicine published a paper emphasizing a new mnemonic for soft tissue healing and promoting this resiliency as opposed to the age-old rest, ice, compression, elevation (RICE) method. That mnemonic being PEACE (protect, elevate, avoid anti-inflammatories, compression, education) and LOVE (load, optimism, vascularization, exercise).⁷ Load is right there in the mnemonic; the body needs to be loaded to heal. Self-management of and care for any healing injury requires load and movement, early and often once symptoms allow.

And what is the appropriate load to promote optimal healing? Let your body tell you that, let your symptoms guide your recovery. If it’s painful, don’t do it, if it isn’t, go for it. Some good examples of early, safe loading for the knee might be a stationary bike or simple heel slides to promote mobility maintenance. From here you could progress to walking for short distances, pushing that distance further as symptoms allow. Sit-stands with equal weight on both feet and mini-squats with support for safety are great options for early, safe loading of the knee. Heel raises, toe raises, and hamstring curls are other great options to promote early, safe mobilization of the structures around the knee depending on the structures involved.

The point is that the evidence for healing no longer supports a passive approach to care, but rather an active one. Our body is meant to move and needs that stimulus in order to adapt, change, and heal. And we need to start shifting away from the old model of care, from the idea that movement is dangerous and harmful following injury. Not only does this inhibit healing, but it also instills fear in ourselves and promotes apprehension with movement. And when it comes to injury prevention, progressively loading our body and doing so often is necessary to promote growth, remodeling, and tissue strengthening. No matter your demographics, the body can be and needs to be loaded often. So whether it be OA, ITB Syndrome, Patellar Tendinopathy, and most other knee injuries that plague our elderly or our athletes, load early, load often, and load progressively; just listen to your body so you do it safely.

Now let’s shift focus one more time, away from loading and healing the knee. Let’s now talk about some other modes of self-care and self-management of the knee. In medicine we often throw band-aids on weeping wounds rather than clean the wound up and seal it for good. In other words, we treat the symptoms rather than the cause with inorganic substances like heavy drugs; substances that alter our body’s natural chemical balance and interrupt our body’s natural healing processes. Not to mention the endless list of unwanted side effects we see with these medications. But it’s the quick fix, so many people go for it. This is why supplements intrigue the general population, myself included. And for good reason, if there’s a safer way to preserve joints and maintain bone health with fewer risks and less significant side effects, I want in! Chondroitin and Glucosamine, for example, have been long been touted for assisting in joint preservation and management of joint pain. Although in more recent years, evidence suggests limited benefit and potential risk. A 2016 study even reported worsening of symptoms for subjects taking a compound chondroitin and glucosamine supplement compared to controls.⁸ Point is, we’re far from understanding which supplements are effective at maintaining joint health. One supplement that has intrigued me as of late is collagen. So let’s go there; let’s talk about collagen.

 

Can Collagen Help Knee Pain?

First off, what is collagen? And why might taking collagen for knee pain be a good idea? Collagen is the most concentrated protein in the human body and is the major structural component of most of our connective tissues (e.g. muscles, ligaments, cartilage, bones, tendons, etc.). In fact, collagen makes up about one-third of the total protein in the human body. In other words, without collagen, our bodies would quite literally crumble underneath us. It even makes up our skin and nails! So yeah, it’s pretty important.

Now generally, the body takes care of making collagen for us. Remember, the human body is amazing. Under normal conditions, the body makes collagen from individual amino acids (protein parts) with a little help from Vitamin C; a wonderful process. But the cold hard fact is, collagen turnover (degradation and formation) rate declines early in life. Studies suggest already by age 20 collagen synthesis takes a blow.⁹ So maybe our bodies aren’t doing quite as good a job as we once thought. This degradation process could wreak havoc on our bodies, joint specifically.

Think about our athletes in what’s supposed to be their prime, the peak of their performance! It’s also been suggested that reduced collagen turnover rates have been associated with bone brittleness and decreased bone mineral density leading to osteoarthritic changes in the body; a problem more relevant for our older populations.⁹ No matter our age or activity level, collagen matters. That’s why collagen supplementation may prove valuable. If we can start supporting our bodies normal processes with collagen supplementation, why not? Right? And yes, there is some supporting evidence for collagen supplementation in these populations!

A recent study found significant improvement in activity-related knee pain in a young, healthy, active population using 5 g of collagen supplementation daily.¹⁰ Other studies have reported similar effects in the aging population. A 2018 study determined that collagen peptide supplementation also improved functional activity tolerance and decreased pain in those with osteoarthritis.¹¹

Additionally, a 2015 study found that elderly men with sarcopenia, or muscle loss due to aging, experienced improved body composition and muscular strength gains with collagen peptide supplementation over the course of a new resistance training regimen.¹² Pretty awesome that both our athletes and aging population might benefit from collagen supplementation. And the best part; collagen supplementation has been proven to be safe.¹³

The current body of evidence speaks for itself. And hey, if there’s a safe and effective way to promote maintenance of joint structure and function as well as quality of life for people of all ages, collagen supplementation is worth it!

In a reputable study by well-known nutrition scientist Keith Baar, PhD, he noted that supplementation of vitamin-C enriched gelatin in combination with specific tendon-focused training increased collagen type I synthesis in subjects ⁽²⁾⁽⁴⁾. This study is compelling because they compared the amount of collagen in the blood of human subjects, and that of ‘engineered’ tissues that were lab-grown from stem cells. The findings showed that the engineered tissues demonstrated improved mechanical properties, and collagen concentration. Within blood samples collected from the subjects, the researchers found that the amounts of an important amino acid called glycine also increased ⁽²⁾⁽⁴⁾. This study in particular lays the groundwork for further investigation into the positive effects of supplementing these proteins and vitamins along with training.

While Baar’s research focuses primarily on the combination of collagen/gelatin and vitamin C, there is a significant amount of research that looks at Type 2 Collagen (UC-II®) supplementation and its benefits on joint and tendon health. In this 2013 study by Lugo et al, the researchers found that“after 120 days of supplementation, subjects in the UC-II group exhibited a statistically significant improvement in average knee extension compared to placebo (81.0 ± 1.3º vs 74.0 ± 2.2º; p = 0.011) and to baseline (81.0 ± 1.3º vs 73.2 ± 1.9º; p = 0.002). The UC-II cohort also demonstrated a statistically significant change in average knee extension at day 90 (78.8 ± 1.9º vs 73.2 ± 1.9º; p = 0.045) versus baseline. No significant change in knee extension was observed in the placebo group at any time.” ⁽²⁰⁾

In 2016, James Lugo and his group of researchers again studied the benefits of Type 2 Collagen on knee osteoarthritis pain, concluding “This study found that UC-II, a nutritional ingredient containing undenatured type II collagen, significantly improved knee function in OA subjects by day 180, compared to placebo and to GC, and was well-tolerated.” ⁽²¹⁾

This is why we at Upper Echelon Nutrition created a tendon and joint support formula which contains 100 mg of Vitamin C, 15 grams of Collagen Peptides, and 40 mg of Undenatured Type 2 Collagen known as UC-II® in line with research like Baar’s and others. ^{(20, 21)} Based on the research, we feel that this combination of Type 1, 2, and 3 Collagen along with Vitamin C can be highly beneficial when combined with an appropriate training regimen. The inclusion of Vitamin C is important for a few reasons, mainly because “preclinical studies demonstrated that vitamin C has the potential to accelerate bone healing after a fracture, increase type I collagen synthesis, and reduce oxidative stress parameters” ⁽²²⁾ or in other words, Vitamin C is essential for the synthesis of collagen and has an essential role in connective tissue healing.

 

 

 

Knee Pain – Putting It All Together

Back to it; so what’s the point? Right? What’s the point in getting so in-depth with knee pain? The point is, knee pain is complex, multi-faceted, ever evolving, and scary. But it doesn’t have to be. It doesn’t have to be overly complicated or scary, no matter your diagnosis or age. Because the human body has one of the most intricate and successful systems to inherently heal itself under the right conditions. Knee pain doesn’t have to mean surgery, medications, or injections. Knee pain can rather just be a simple reminder that our body is searching for “something” more to maintain itself. And more often than not, that “something” is load; safe, appropriate, progressive load of the body to give it the stimulus it needs to change, adapt, and become stronger as well as prevent and manage pain. Under-loading our bodies, in my opinion, is one of the most detrimental trends our healthcare industry has followed for centuries. When the body hurts, stop using it, that’s been the mentality. When instead, pain is often just a reminder to our body that it needs a little more help from our musculoskeletal system; more strength, more endurance, more movement, certainly not less. Loading is under prescribed and our health is suffering because of it. So next time you have knee pain, instead of looking for the quick fix, seek out your local movement expert instead. Find someone that can prescribe safe, appropriate, and progressive loading, and help your body heal intrinsically. Because no matter your age or condition, your body only stands to benefit from the appropriate prescription of movement and loading. And in the meantime, start looking into what you can do for yourself to prevent injury and pain in the future. Prehab instead of eventually having to rehab. Aches and pains are often much easier to prevent than to treat. So get moving, find out what sort of load your body needs, and do it often.

 

References

1. Knee pain. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/knee-pain/symptoms-causes/syc-20350849. Published March 7, 2019. Accessed September 28, 2020.
2. Knee Pain and Problems. Knee Pain and Problems | Johns Hopkins Medicine. https://www.hopkinsmedicine.org/health/conditions-and-diseases/knee-pain-and-problems. Accessed September 28, 2020.
3. Physical Therapy Guide to Iliotibial Band Syndrome (ITBS or "IT Band Syndrome"). American Physical Therapy Association. https://www.choosept.com/symptomsconditionsdetail/physical-therapy-guide-to-iliotibial-band-syndrome-itbs. Published August 18, 2020. Accessed September 28, 2020.
4. Patellar Tendonitis (Jumper's Knee). Patellar Tendonitis (Jumper's Knee) | Johns Hopkins Medicine. https://www.hopkinsmedicine.org/health/conditions-and-diseases/patellar-tendonitis-jumpers-knee. Accessed September 28, 2020.
5. Schwartz A, Watson JN, Hutchinson MR. Patellar Tendinopathy. Sports Health: A Multidisciplinary Approach. 2015;7(5):415-420. doi:10.1177/1941738114568775.
6. Grassi A, Quaglia A, Canata G, Zaffagnini S. An update on the grading of muscle injuries: a narrative review from clinical to comprehensive systems. Joints. 2016;04(01):039-046. doi:10.11138/jts/2016.4.1.039.
7. Dubois B, Esculier J-F. Soft-tissue injuries simply need PEACE and LOVE. British Journal of Sports Medicine. 2019;54(2):72-73. doi:10.1136/bjsports-2019-101253.
8. Roman-Blas JA, Castaneda S, Sánchez‐Pernaute O, Largo R, Herrero‐Beaumont G. Combined Treatment With Chondroitin Sulfate and Glucosamine Sulfate Shows No Superiority Over Placebo for Reduction of Joint Pain and Functional Impairment in Patients With Knee Osteoarthritis: A Six‐Month Multicenter, Randomized, Double‐Blind, Placebo‐Controlled Clinical Trial. Arthritis & Rheumatology. 2016;69(10):2080-2080.
9. Kehlet SN, Willumsen N, Armbrecht G, et al. Age-related collagen turnover of the interstitial matrix and basement membrane: Implications of age- and sex-dependent remodeling of the extracellular matrix. Plos One. 2018;13(3). doi:10.1371/journal.pone.0194458.
10. Zdzieblik D, Oesser S, Gollhofer A, König D. Improvement of activity-related knee joint discomfort following supplementation of specific collagen peptides. Applied Physiology, Nutrition, and Metabolism. 2017;42(6):588-595. doi:10.1139/apnm-2016-0390.
11. García-Coronado JM, Martínez-Olvera L, Elizondo-Omaña RE, et al. Effect of collagen supplementation on osteoarthritis symptoms: a meta-analysis of randomized placebo-controlled trials. International Orthopaedics. 2018;43(3):531-538. doi:10.1007/s00264-018-4211-5.
12. Zdzieblik D, Oesser S, Baumstark MW, Gollhofer A, König D. Collagen peptide supplementation in combination with resistance training improves body composition and increases muscle strength in elderly sarcopenic men: a randomised controlled trial. British Journal of Nutrition. 2015;114(8):1237-1245. doi:10.1017/s0007114515002810.
13. Benito-Ruiz P, Camacho-Zambrano M, Carrillo-Arcentales J, et al. A randomized controlled trial on the efficacy and safety of a food ingredient, collagen hydrolysate, for improving joint comfort. International Journal of Food Sciences and Nutrition. 2009;60(sup2):99-113. doi:10.1080/09637480802498820
14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4650849/
15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5183725/
16. Di Lullo, Gloria A.; Sweeney, Shawn M.; Körkkö, Jarmo; Ala-Kokko, Leena & San Antonio, James D. (2002). "Mapping the Ligand-binding Sites and Disease-associated Mutations on the Most Abundant Protein in the Human, Type I Collagen"
17. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5371618/
18. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4527202/

19. Trč, T., Bohmová, J. Efficacy and tolerance of enzymatic hydrolysed collagen (EHC) vs. glucosamine sulphate (GS) in the treatment of knee osteoarthritis (KOA). International Orthopaedics (SICOT)35, 341–348 (2011). https://doi.org/10.1007/s00264-010-1010-z
20. Lugo JP, Saiyed ZM, Lau FC, et al. Undenatured type II collagen (UC-II®) for joint support: a randomized, double-blind, placebo-controlled study in healthy volunteers. J Int Soc Sports Nutr. 2013;10(1):48. Published 2013 Oct 24. doi:10.1186/1550-2783-10-48
21. Lugo JP, Saiyed ZM, Lane NE. Efficacy and tolerability of an undenatured type II collagen supplement in modulating knee osteoarthritis symptoms: a multicenter randomized, double-blind, placebo-controlled study. Nutr J. 2016 Jan 29;15:14. doi: 10.1186/s12937-016-0130-8. PMID: 26822714; PMCID: PMC4731911.
22. DePhillipo NN, Aman ZS, Kennedy MI, Begley JP, Moatshe G, LaPrade RF. Efficacy of Vitamin C Supplementation on Collagen Synthesis and Oxidative Stress After Musculoskeletal Injuries: A Systematic Review. Orthop J Sports Med. 2018;6(10):2325967118804544. Published 2018 Oct 25. doi:10.1177/2325967118804544