The Connectivity of Injuries


Muscles, tendons, ligaments and joints are often viewed as mechanical structures and if injury occurs, it’s just unlucky. Ian Craig looks at how to nourish our injuries.

Connective Tissue Networks

The last issue of TSN saw a thought provoking article on the subject of Pilates by Charlene Hutsebaut, which considered the concept of Myofascial Lines as conceptualised by Thomas Myers (1). According to Myers, there are three networks within the body which hold it together and allow it to function as synchronously as it does: the nervous system, the vascular system and the network of connective tissue. In this way, 70 trillion cells can live together harmoniously within the confines of our body.

This view of the body as not just a collection of parts mirrors that of Functional Sports Nutrition, which understands the beautiful integration of systems that occurs in order for the body to not only survive, but to thrive. The connective tissue network spreads out from the spine to create a protective net around all the cells, structures and systems. There are Front Lines, Back Lines, Lateral Lines, Arm Lines and Spiral Lines that make up this network: the Spiral Lines are shown in Figure 1. All of the three networks communicate with each other: the nerves carry sensory information in and out of the body; our blood vessels constantly circulate oxygen and nutrients; and the connective tissue system communicates mechanical information via the matrix of fascia, tendons, ligaments, cartilage and bones.


Figure 1: The Spiral Line of Connective Tissue (1)

What Constitutes Connective Tissue?

If we focus in specifically on the connective tissue as the basis of the fascia, tendons, ligaments, cartilage and bone plus the structure that binds muscles together, we can see that it is potentially a major source of injury for the high achieving athlete, whether elite or recreational. Let’s break this tissue down further to see what it’s made of – perhaps then we can understand how to use nutrition to our advantage. The matrix of connective tissue is made of collagen fibres, elastin fibres, fluid, migrating immune cells, stem cells and carbohydrates called ‘GAGs’ (glycosaminoglycans).

If you take a look at Figure 2, we have the example of a load-bearing connective tissue in the form of the cartilage in our joints. Hyaluronic acid is represented as single strands with brush-like projections coming out of them – these are the ‘GAGs’, available in supplement form as glucosamine and chondrotin sulphate. The roles of the GAGs are to attract water into the cartilage to give it a kind of padding. The role of the collagen fibres, on the other hand, is to provide structural support to the tissue.


Figure 2: Connective Tissue of Cartilage (2)

What is Collagen?

Collagen, as the structural unit of connective tissue, is the most abundant protein in the animal world, constituting more than 30% of the total protein of the human body (3). It is found mostly in fibrous tissues like tendons, ligaments & skin, but also bone, cartilage, blood vessels, the gut & muscles. It is made out of the amino acids proline, glycine and lysine (4). As shown in Figure 3, collagen fibres are made from three long chains (each about 1000 amino acids long) intertwined in a helical structure. The stability of the collagen fibres are increased by cross-links within the fibres and between adjoining fibres. It is widely known that Vitamin C is vital for the cross-linking of collagen fibres (4) and that deficiency of Vitamin C can result in distorted, non-functional accumulation of scar tissue (5), otherwise known as scurvy. It is the cross-linking that gives collagen its strength and stability. In fact, Yilmaz and colleagues (6) fractured the right tibia of 16 poor rats by digital manipulation and provided a high-dose supplement of Vitamin C to half of the animals. It was seen that the vitamin C-supplemented group went through the stages of fracture healing faster compared to the control group.


Figure 3: Triple Helix Structure of Collagen

When Injury Strikes

In normal tissues collagen provides strength, integrity and structure. However, when tissues are disrupted by injury, collagen is needed for the repair and restoration of function. After injury has occurred, it is the fibroblasts that produce new collagen. Fibroblasts are stem cells that have differentiated into fibrous connective tissue cells in places like tendons and ligaments and have an important role in wound healing (2). At least 23 individual types of collagen have been identified to date but type I is predominant in the scar tissue of skin (5). If too much collagen is laid down during repair, the tissue becomes fibrous and if not enough collagen is deposited, the wound becomes weak.

The collagen in healthy tissue is strong and organised and on a basis of weight is nearly as strong as steel. However, collagen fibres in scar tissue are smaller and more random and at best can achieve only 80% of normal strength (5). Since the scar tissue is weaker than surrounding healthy tissue, it will become susceptible to further injury, which makes it even more important to optimise collagen repair or even better, to reduce the likelihood of injury in the first place.

Genetics of Collagen

As noted, there are many different types of collagen depending on which tissue they are most prevalent in. Type I is the most abundant type and is found in skin, bones, tendons and ligaments; Type II is mostly found in cartilage; Type III is found in the skin and blood vessel walls; Type IV is found in secretary membranes; Type V is found in tendons and ligaments (2).

Two collagen genes have received a lot of attention with regards to tendon and ligament injuries. Athletes with a certain genotype for the Collagen 5A1 gene appear to have fewer tendinopathies (7) than the other gene options. These people also seem to have a better range of motion (8), which might decrease injury risk. Additionally, one of the gene options for Collagen 1A1 seems to increase collagen production and decrease the likelihood of ligament sprains and Achilles tendon injuries (9).

Connective Tissue Nutrition

So why am I telling you all of this theory about connective tissue and collagen and injuries? One of our jobs at this magazine is to put theory into practice and this topic is no different. We need to remember that all of these physical structures that we’ve talked about are made from certain building blocks that have to come from our diet. I’ve explained to you step-by-step what each of the physical structures within connective tissue are made from, so it gives us a clue as to what we should be eating to support them. Collagen has had most of the attention in this article, so let’s start with that. 


Well-absorbed dietary proteins are extremely important. As noted, the amino acids proline, lysine and glycine are required for collagen synthesis within connective tissue; the branch-chain amino acids (valine, leucine and isoleucine) are needed for muscle synthesis and metabolism (4); and nitric oxide, which requires the amino acid arginine for synthesis, is important for blood flow and collagen synthesis (10). Nitric oxide is normally up-regulated following injury but if inhibited, tendon healing has been shown to be reduced.

Vitamin C is needed for the structural strength of collagen and has consequently been used to treat many collagen disorders (4). Vitamin C, along with Vitamin E and other antioxidants are also essential to buffer the consequences of oxidative stress, which is likely to be prevalent during injury. Foods high in Vitamin C include bell peppers, broccoli, papaya, strawberries, pineapple, kiwi fruit and oranges (11).

Consequently, well-absorbed proteins from the diet are essential for optimal collagen support and healing and in many cases, a protein powder such as whey or soya or rice, might be useful. Another useful supplement is Hydrolysed Collagen powder which will provide the appropriate amino acids for collagen repair in an easily absorbable form. Vitamin C can also be supplemented to support collagen, but be aware of the ongoing debate about antioxidant supplements – some researchers think that excess quantities might actually impede recovery from training or injury.

Glycosaminoglycans (GAGs)

GAGs, as noted above, are vital for the hydration of connective tissue within tendons, ligaments and cartilage. Glucosamine and chondroitin sulfate are major components of GAGs, making them vital for the synthesis of new connective tissue during the healing process. With respect to cartilage repair, glucosamine supplementation has gained most of the research attention and 2000mg has been shown to significantly reduce joint pain and improve function in as little as 8 weeks (12), but chondrotin is also recognised for beneficial joint function (13). Sulphation (from the sulphur in either of these products or from MSM) is also important to optimise GAG synthesis for healthy cartilage (14).


In addition to providing sufficient protein through your diet, ensuring sources of Vitamin C and potentially supplementing glucosamine or chondrotin, it is important to eat a diet that is rich in plant foods. Not only do fruits and vegetables boost your daily level of antioxidants, which are important to reduce tissue damage, but they also help to decrease levels of inflammation that might be associated with hard training and injury. We will discuss more on oxidative stress and inflammation in future issues of TSN.


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  2. Whiting WC & Zernicke RF (1998). Biomechanics of Musculoskeletal Injury. Human Kinetics.
  3. Eyre DR (1980). Science. 207:1315-1322.
  4. Bralley & Lord (2000). Laboratory Evaluations in Molecular Medicine. Nutrients, Toxicants and Cell Regulators. IAMM
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  6. Yilmaz et al. (2001). Arch Orthop Trauma Surg. 121(7):426-428.
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  13. Bledsoe (2008). Sports Injury Bulletin.
  14. Murch SH et al (1993). Lancet. 341(8847):711-714.