In the first of this two-part article, Andrew Hamilton explored how the ageing process can affect endurance performance. In this second part, Andrew looks at evidence-based strategies that older endurance athletes can employ to maintain and even increase performance levels over time… MORE
Veteran athletes – degenerative joints
The best foods and supplements to protect your joints from age-related degeneration
There’s good and bad news for veteran athletes. The good news is that, if training intensity can be maintained, age-related performance decrements are actually quite minimal; the bad news is that recovery from hard training sessions takes longer, while the cumulative effects of normal ‘wear and tear’ and previous injuries are increasingly evident. As time goes by, joints tend to become less flexible, full-range movement more difficult and pain and stiffness ever more apparent. It is these mechanical limitations, more than anything else, which can scupper the best-laid plans of even the most determined veteran athletes!
However, there are a number of nutritional strategies that can help to offset the inexorable decline in mobility and even accelerate recovery from injury.
Before we get down to nutritional nuts and bolts, it’s worth outlining some of the causes of joint degeneration and immobility. Basically, a joint exists whenever two bones meet. Many joints are freely moveable, allowing large ranges of movement; for example, the knees, ankles, hips, elbows and fingers. Others, such as those between the spinal vertebrae, allow for only partial movement. There are even some fixed joints, such as those in the skull, although maintaining range of motion is obviously not an issue here!
The freely moveable joints are generally ‘synovial’-type joints, where the two ends of the bones that meet are covered with ‘articular cartilage’ – a sort of ‘low friction’ coating. Although the two bones are in fairly close proximity, they don’t actually touch, being separated by a joint cavity, which is like a fluid- filled sac. The walls of this cavity are lined with synovial membrane, which secretes synovial fluid into the cavity to lubricate the movement between the two cartilage surfaces. Meanwhile, the whole joint structure is stabilised by ligaments – tough fibrous tissues connecting and anchoring the two bones.
The joints between the vertebrae of the spine are slightly different in that the movement between any two adjacent vertebrae is quite restricted. However, the cumulative effect of several small intervertebral movements allows for a large degree of global movement of the spinal structure as a whole. Another difference is that the main joints between the vertebral bodies are ‘cartilaginous’, containing an intervertebral disc. These discs are like soft pads, which allow relative movement between adjacent vertebrae and can accommodate the different curvature requirements of the spine at different points along its length.
There are a large number of possible causes of joint pain and stiffness, and the diagnosis of a particular problem can be a very complex process – just ask any physiotherapist! In general terms, however, there are a number of well-recognised causal factors.
- Acute injuries come on suddenly and are usually associated with some kind of trauma. Common examples include:
- ligaments torn or damaged by unusual or excessive movement of the joint;
- impact injuries, where one of more of the joint structures is damaged by an external blow;
- protruding/prolapsed intervertebral disc, where unusual intervertebral forces lead to the deformation of the disc, allowing it to come into close proximity with nerves.
- Chronic injuries usually come on quite gradually, which tends to make them trickier to diagnose and harder to overcome. Common examples include:
- overuse injuries, where the long-term training volume exceeds the capacity of the joints involved to undergo adequate repair and recovery;
- muscle imbalance injuries, where the joint fails to operate through its correct range of movement because of unequal or unbalanced muscular forces acting on the joint, or (particularly in the case of the spine) inadequate stabilisation of the joint(s) by the deep postural muscles.
- Degenerative conditions are associated with longer-term, less easily reversible functioning of the joints and are much more common in mature athletes. While previous acute or chronic injuries are known to increase the risk of long-term degeneration, simple ageing factors also come into play. These conditions frequently include:
- arthritic-type wear and tear, where the articular cartilage becomes worn, leading to narrowed joint spaces, sometimes referred to as osteoarthritis;
- rheumatoid arthritis, an inflammatory condition of the joints caused by an auto-immune reaction;
- low synovial fluid secretions, leading to reduced lubrication in the joint capsule.
Common to all these causal factors is the process of inflammation which, although part of the normal healing process, can actually impede this process when it becomes chronic.
The role of nutrition in combatting degenerative or inflammatory joint conditions has traditionally been regarded with scepticism, but in recent years research has indicated that good nutritional practice can play a significant role, both in promoting recovery from acute and chronic injuries and in ameliorating some of the effects of the degenerative conditions described above.
We’ll begin by taking a look at the latest thinking on optimum dietary practice, then move on to examine the claims of some of the more esoteric ‘joint health’ nutrients on offer!
As with all athletes, it is important for older athletes looking to maximise joint health to consume a whole, natural and unprocessed diet, rich in fruit, vegetables, complex carbohydrates (such as whole grains, starchy vegetables, beans, peas and lentils) and high-quality, low-fat sources of protein, keeping processed, refined, fatty and sugary foods to a minimum. However, there are a number of nutrients that are particularly important for older athletes, which should be well supplied in their diet. These and their effects are described below.
Among other roles in the body, vitamin C is vital for the formation of collagen, which is a protein forming the basis for connective tissue, such as tendons and intervertebral discs. Vitamin C activates the enzymes that convert proline and lysine into hydroxyproline and hydroxylysine respectively, both of which are needed to give collagen its correct 3D structure.
Prostaglandins (PGs) are short-lived hormone-like chemicals synthesised from dietary fatty acids to regulate cellular activities. There are three families of prostaglandins – series 1, 2 and 3. Series 1 PGs play a number of roles in the body, including exerting an anti-inflammatory effect. By contrast, series 2 PGs exert an inflammatory effect; (remember that inflammation can be a good thing when it is required!)
While series 1 and 2 PGs are synthesised from the omega-6 essential fatty acid, ‘linoleic acid’, series 3 PGs are synthesised from the other essential fatty acid, omega-3 alpha-linolenic acid. One of the intermediate steps during the conversion of alpha-linolenic acid to series 3 PGs involves the formation of eicosapentaenoic acid (EPA). EPA acts to inhibit the excessive formation of the inflammatory series 2 PGs, and this explains why omega-3 oils exert an anti-inflammatory effect in the body, and why fish oils (which contain ‘ready-made’ EPA) have been shown to have the same effect.
Sulphur-containing amino acids
Sulphur has long been recognised as an essential nutrient for human health. In the diet, sulphur is found in a number of forms, but mainly as the sulphur-containing amino acids methionine, cysteine and taurine. Dietary sulphur is also present as inorganic free sulphate and loosely bonded sulphates. Because these forms are present in much smaller amounts, they have been considered relatively unimportant. However, recent research has shown that inorganic sulphates in the diet can be used not only to synthesise cysteine and taurine but also to synthesise the chondroitin matrix of joint cartilage (1); (chondroitin helps to promote water retention and elasticity in joint cartilage and inhibit enzymes that break down cartilage.)
In the body, sulphur is present in a number of compounds critical for joint function and health, in addition to the sulphur-containing amino acids (SAAs). Glutathione is a powerful antioxidant, which can be depleted during heavy training. If intakes of the SAAs methionine and cysteine are sub-optimal, cysteine can be preferentially incorporated into body proteins, producing a pro-inflammatory response (2).
Chondroitin sulphate is a sulphur-containing polysaccharide essential for joint cartilage health, while glucosamine is an amino-acid-containing monosaccharide, concentrated in joint cartilage, which is used to synthesise cartilage glycosaminoglycan (GAG for short) GAGs are large molecules comprising long-branched chains of sugars and smaller nitrogen-containing molecules known as amino-sugars.
Methlysulphonylmethane (more commonly known as MSM) is another sulphur-containing compound found in some foods, which is also present in the body. Although the biochemistry of MSM is poorly understood, it appears to be able to donate some of its sulphur for the formation of connective tissue and may also have an anti-inflammatory effect. Meanwhile S-adenosylmethionine (SAMe) is another sulphur-containing compound in the body (produced from the metabolism of methionine), which also appears to exert an anti-inflammatory effect. We’ll revisit these last four compounds later in this article.
These are naturally occurring compounds found mainly in fruit and vegetables, which appear to possess anti-inflammatory properties in addition to their antioxidant effects. Animal studies on two such compounds, rutin and quercetin, have demonstrated significant anti-inflammatory effects in both acute and chronic inflammation (3). Furthermore, there is also evidence that these compounds improve local circulation and promote a strong collagen matrix in joints (4).
When free radical damage occurs in joint linings, inflammation can be increased. There are a number of antioxidant nutrients that afford protection from free radical damage in the body, but selenium and vitamin E appear to be especially important. Vitamin E has been shown to help combat the effects of exercise-induced oxidative stress (which increases free radical production), while selenium is an essential component of the critically important antioxidant enzyme called glutathione peroxidase, as well as being involved in the production of the prostaglandins and substances known as leukotrienes that are also involved in regulating inflammatory processes (5).
Zinc and copper
Zinc is an important mineral, activating numerous enzyme systems in the body. These include enzymes that process amino acids in the body (including the SAAs) – a process known as transamination. Zinc also functions as an antioxidant and is able to protect sulphur-containing bio-molecules from oxidation. Additionally, sub-optimum intakes of zinc are known to impede the formation of collagen (6). Like zinc, copper is needed for important antioxidant enzymes (eg superoxide dismutase) and is also required for collagen formation.
Key sources of these nutrients are listed in table 1, below.
|Nutrient||Good sources in the diet|
|Vitamin C||Grapefruit, lemons, oranges, kiwis, strawberries, raspberries, blackberries, blackcurrants, pineapple, papaya, peppers, tomatoes, cabbage, broccoli, Brussels sprouts, new potatoes|
|Omega-3 oils||Walnuts, pumpkin seeds, flax and flax-seed oil, herring, trout, mackerel, salmon, sardines, pilchards, wheat germ|
|Bioflavanoids||All fruit and vegetables, especially citrus fruit (particularly the pith), apricots, cherries, grapes, green peppers, tomatoes, broccoli. Buckwheat (a cereal) is also a good source|
|SAAs||Broccoli, cabbage, onion, garlic, eggs, meat, poultry, fish, milk and cheese, oats, corn, sunflower seeds|
|Vitamin E||Almonds, sunflower seeds, spinach, wheat germ, whole grain breads and cereals, cold-pressed seed oils, egg yolk|
|Selenium||Brazil nuts (extremely good source), tuna, whole grain breads and cereals, swordfish, herring|
|Zinc||Oysters, lean beef, pumpkin seeds, lamb, peanuts, crab meat, pork, sunflower seeds, wholemeal flour and bread, turkey|
|Copper||Beef liver, oysters, lobster, sunflower seeds, hazelnuts, crab, baked beans, chickpeas, lentils, wholemeal bread and whole grain cereals|
In addition to ensuring a good supply of the above nutrients, it is important to avoid excessive intakes of saturated fats from red meats, full fat dairy produce etc, as these tend to be rich in arachidonic acid, which is a precursor to the inflammatory series 2 PGs. Likewise, too much omega-6 and insufficient omega-3 oils (a common imbalance in Western diets) enhances the production of series 2 PGs (see PP190, December 2003).
The importance of the sulphur amino acids is worth emphasising. The US committee on recommended daily amounts suggests a combined SAA intake of around 1g per day for a typical adult. Other authorities believe this figure is too low and should be closer to 2g per day (7,8). Given that the stress of heavy training can deplete blood glutathione, which is an important peptide and reservoir for the SAA cysteine, athletes need to take more care than most people(9,10). This is especially true for those on low protein or strict vegetarian diets, which tend to supply lower levels of SAAs per calorie consumed. Vegetarians may wish to note that corn, sunflower seeds, oats, chocolate, cashew nuts, walnuts and almonds are all good very sources of methionine, while oats and corn are high in cysteine too!
Assuming that your diet is optimal, are there any food supplements that can further improve joint health, both in terms of helping to overcome acute and chronic injuries and in combating the long-term degeneration that is an inevitable part of the ageing process? Those which might be useful are described below.
Glucosamine is used in the manufacture of very large molecules found in cartilage, called proteoglycans. These are large linear chains of repeating polysaccharide units (GAGs), which radiate out from a protein core like the bristles of a bottlebrush and can attract and hold water like a sponge. When compressed, this bound water helps to absorb force and distribute it equally, which explains the ability of cartilage to protect the joints under load and during movement.
In the body, these GAG chains are synthesised from glucose, the amino acid glutamine, and sulphate, but there’s plenty of evidence that additional supplementation not only increases GAG significantly but can also relieve the pain and inflammation associated with osteoarthritis(11).
Last year, researchers carried out an exhaustive meta-analysis of all the randomised, placebo-controlled clinical trials (RCTs) on the efficacy of oral glucosamine that were published or performed between January 1980 and March 2002 (12). They concluded that the supplement was not just highly effective in reducing pain and increasing mobility but also reduced the joint space narrowing that typically occurs in degenerative conditions.
The long-term benefits of oral glucosamine sulphate appear to be supported by a three-year study in which 200 patients with osteoarthritis of the knee were randomised to receive either oral glucosamine sulphate (1500mg daily) or placebo. By the end of the study, average joint spaces had reduced by more than 5% in the placebo group, while the glucosamine group showed no narrowing at all! Moreover, pain and stiffness was significantly reduced in the glucosamine group by comparison with the controls. (13)
The pain relief afforded by glucosamine is also significant. In a mini meta-analysis of two double-blind RCTs, oral glucosamine sulphate (1.5g/day) was compared with ibuprofen (1.2g/day) for the relief of joint pain in osteoarthritis and was shown to be equally effective (14). Even more persuasive is the fact that many non-steroidal anti-inflammatory drugs (NSAIDS), including ibuprofen, have been shown to inhibit the repair and even accelerate the destruction of cartilage (15). In fact, the only drawback to using glucosamine is that the benefits take a while to accrue, with most users finding it takes a good six or so weeks before the full effects are felt.
This is another of the GAG polysaccharides found in cartilage. But whereas glucosamine appears to promote the formation and repair of cartilage, chondroitin seems to promote cartilage water retention and elasticity. Initially it was believed that, as a big molecule, chondroitin couldn’t be absorbed intact. But subsequent research has shown not only that up to 15% is absorbed whole but also that, once in the body, chondroitin makes beeline for GAG-rich tissues such as the joints and lumbar discs (16).
Although fewer studies have been carried out on chondroitin than on glucosamine, the evidence points very strongly towards its efficacy. In the large meta-analysis described above (12), the outcomes of supplementing chondroitin were also observed and it was found to be effective in reducing pain and increasing mobility. Moreover, chondroitin also appears to offer long-term benefits in arthritic conditions. In a one-year Swiss RCT of 42 patients with knee pain, those taking 800mg of chondroitin per day showed significantly reduced pain and increased overall mobility compared with those on placebo (17). In addition, the metabolism of bone and joint, as assessed by various biochemical markers, stabilised in the chondroitin group but remained abnormal in the placebo group.
This micronutrient is extremely rich in sulphur (containing 34% elemental sulphur by weight) and is found in small amounts in fruit, alfalfa sprouts, tomatoes, tea and coffee. Despite its rapidly growing popularity as a supplement, its metabolism in the human body remains poorly understood. One study found that 97% of orally ingested MSM is converted into other metabolites, while its very high sulphur content has led researchers to speculate that it could act as a sulphur donor in the synthesis of sulphur amino acids(18). However, studies on guinea pigs, using radio-labelled MSM, showed that only 1% of the sulphur is actually incorporated, so this seems unlikely (19).
By comparison with glucosamine and chondroitin, scientific studies of MSM supplementation for joint health are thin on the ground. In a preliminary study carried out on 16 patients with degenerative arthritis, one group received 2,250mgs per day of MSM and the other a placebo (20). After six weeks, eight out of 10 patients in the MSM group experienced significant pain relief compared with just one who experienced minimal pain relief in the placebo group.
Another RCT was conducted on athletes with acute injuries, who were undergoing routine chiropractic manipulation, ultrasound and muscle stimulation (21). On average, those taking MSM were discharged from care after just 3.25 visits and experienced a 58.3% reduction in symptom severity, while those on placebo needed 5.25 visits and experienced a reduction in symptom severity of just 33.3%. While these results are encouraging, both of these studies were sponsored by suppliers of MSM, and further independent peer-reviewed trials are needed before firm conclusions about the efficacy of MSM can be drawn.
This is produced in the body by the metabolism of the SAA methionine and, like methionine, SAMe is used in a number of metabolic processes that require sulphur. Normally the body can synthesise all it needs, but low intakes of methionine, or of other co-factors needed (choline, folic acid), or an inherited defect in the ability to carry out a biochemical process known as methylation, are all thought to reduce the body’s ability to make SAMe.
Orally supplemented SAMe has been shown to stimulate the synthesis of cartilage proteoglycans and to be as effective as commonly prescribed NSAIDS (eg ibuprofen) for pain relief(22). A large meta-analysis of RCTs on SAMe found it as effective as NSAIDs in relieving pain and improving functional limitation in patients with osteoarthritis, without the adverse effects often associated with NSAIDS (23). SAMe therapy for joint pain may also offer an advantage over glucosamine in that pain relief appears to occur relatively rapidly – within two weeks (24)!
In summary, despite the fact that older athletes are more vulnerable to chronic joint pain and stiffness, you are not powerless to act. While it is obviously vital to get your training right, and to incorporate any other rehab/injury prevention techniques deemed necessary by your coach/trainer/physiotherapist, there is also a place for nutrition.
Diet before supplements
Your number one priority should be to follow the dietary recommendations outlined earlier, paying special attention to the key joint health nutrients. Only then should you consider supplementation. On the available evidence, glucosamine and chondroitin, supplemented at around a gram per day, both offer effective pain and stiffness reduction, and even appear to be able to slow down the process of cartilage degeneration itself. Their regenerative mode of action means they need to be supplemented on a long-term basis (ie for six weeks or longer), but for those prone to chronic joint stiffness and pain, there’s no reason not to take them indefinitely.
One word of caution: virtually all the studies on glucosamine have been carried out using glucosamine sulphate, and this is the recommended form to use. The evidence in favour of MSM is much less convincing. True, there are promising signs, but there’s simply too little peer-reviewed scientific evidence in the literature to recommend its use unreservedly. Nevertheless, it is also one of the least toxic substances known in biology, so if you want to try it and see for yourself there’s little to worry about(25). Although probably less familiar to most readers, and less extensively researched, SAMe (supplemented at 0.5-1g/day) looks promising for helping to combat joint degeneration. However, drawbacks include its high cost and its chemically fragile nature, which means it needs to be stored in a cool, dry, dark environment from the point of manufacture to consumption. SAMe is also being studied as an alternative and more ‘natural’ anti-depressant; it appears to exhibit significant anti-depressive activity in some people by increasing the levels of two brain neurochemicals, serotonin and dopamine. However, if you are currently taking any anti-depressant medication or receiving any other psychiatric treatment, you should not experiment with SAMe without first consulting your doctor!
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