This is an excerpt from Nutrition for Sport, Exercise, and Health 2nd Edition With HKPropel Access by Marie Spano,Laura Kruskall & D. Travis Thomas.
Although an adequate training stimulus is required for strength, skeletal muscle hypertrophy, and other physiological gains, sometimes the inflammatory side effects can be unpleasant. Many athletes and active people seek supplementation to ease pain and discomfort posttraining.
Creatine and DOMS
In addition to the ergogenic effects of creatine mentioned in the previous section, supplementation offers other potential benefits. Limited research has suggested that creatine supplementation may reduce symptoms of delayed onset muscle soreness (DOMS), improve recovery from immobilization or complete inactivity, improve cognitive function when fatigued from multitasking or sleep deprivation, and hasten recovery from concussion or traumatic brain injury (animal data). More research is needed on these topics before recommendations can be made (2).
Leucine is an essential, branched-chain amino acid that serves as a trigger for skeletal muscle protein synthesis. Beta-hydroxy-beta-methylbutyrate (HMB), a metabolite of leucine, has been reported to have therapeutic effects in people with atrophic conditions and cachexia (wasting) (63-65). Athletes and bodybuilders have expressed an interest in using the compound to increase skeletal muscle strength and hypertrophy.
Early research studies reported that HMB reduces skeletal muscle damage with resistance training. Unfortunately, this area of study has not significantly increased over time, so published research studies are somewhat scarce. The most commonly reported ergogenic effects include reduced muscle damage and increased strength, primarily in novice weightlifters, but minimal data support this claim. No safety concerns or significant side effects have been reported in the literature at this dosage. Based on available research, there does not appear to be an ergogenic benefit in trained persons of all ages with no actual increases in skeletal muscle protein synthesis (66, 67). This supplement might have therapeutic effects in older adults who are confined to bed rest or those with muscle-wasting disease. Any possible benefits of HMB may also be obtained through quality dietary protein sources consumed in proper amounts (2, 63-65).
Glucosamine and Chondroitin
Osteoarthritis is a degenerative joint disease caused by wear and tear of cartilage tissue from excess body weight (one of the top causes), mechanical stress through repetitive motion (running up and down a field for years), and oxidative damage and inflammatory responses from the anabolic-catabolic balance of the joint, synovium, matrix, and chondrocytes (all parts of the working joint). Although some people get this condition later in life as a result of age, many athletes and active people are at risk because of the volume of training and injury history that accompanies many sports (68). Many people seek pain medications, particularly nonsteroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen or aspirin) to decrease their symptoms, but over time NSAIDs can lead to a number of side effects, including stomach pain and ulcers (that might lead to bleeding), heartburn, headaches, and dizziness. For those allergic to NSAIDs, side effects include rashes, throat swelling, and difficulty breathing (69).
Glucosamine and chondroitin sulfate are popular supplements for minimizing the pain of osteoarthritis and delaying progression of the disease. Glucosamine, a naturally occurring amino sugar found in meat, fish, and poultry, is made by cartilage cells. It is used as a building block of the cartilage matrix. Chondroitin sulfate is a type of protein present in cartilage. Research on this topic examines outcomes of reduction in pain and decreased joint space narrowing (more narrow spaces mean less cartilage to cushion joints). Glucosamine sulfate and glucosamine hydrochloride help rebuild the cartilage matrix and decrease activity of an enzyme that damages tissue. Sulfate is a source of the essential nutrient sulfur, which is important for cartilage (70).
Experts disagree about whether glucosamine and chondroitin supplementation may help knee and hip osteoarthritis, the areas of the body most studied. The National Institutes of Health (NIH) conducted a large study called the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT) in patients with mild knee pain due to osteoarthritis. They compared glucosamine hydrochloride, chondroitin, both supplements together, celecoxib (a prescription drug used to manage osteoarthritis pain), and a placebo (an inactive substance). The participants who took the prescription drug had better pain relief at 6 months than those who received the placebo. Those receiving the supplements had no significant improvement in knee pain. On the other hand, several European studies reported that patients felt better after taking glucosamine sulfate. Until more research is complete, people cannot count on glucosamine or chondroitin to relieve arthritis pain in the knee or any other joint. Other than the negative interaction with blood-thinning drugs, glucosamine and chondroitin appears to be relatively safe. People with diabetes should check for the effect on blood sugar if they take glucosamine regularly (71).
Gelatin, Vitamin C, and Collagen
Although data are very limited, a combination of 5 to 15 grams of gelatin combined with 50 mg of vitamin C or approximately 10 grams per day of collagen hydrolysate may increase collagen production in the body, thicken existing cartilage, and reduce perception of pain. These supplements appear to have little to no side effects, but the functional benefits in athletes for maintenance and recovery are not well established at this time (2).
Curcumin is the main active ingredient in the Indian spice turmeric, which gives curry its vivid yellow color. It has been used in India for thousands of years because of the purported powerful anti-inflammatory and antioxidant effects. Limited but promising research suggests curcumin may help with chronic inflammatory conditions, metabolic syndrome, arthritis, anxiety, and hyperlipidemia. It may play a role in recovery for athletes and active people by decreasing exercise-induced inflammation and muscle soreness. Most of the studies use turmeric extracts composed primarily of curcumin with dosages often exceeding 1 gram of curcumin per day. People turn to supplementation because consuming that level through food is difficult and many do not enjoy the taste of the spice in that dosage. Because curcumin is poorly absorbed, it is often combined with piperine, a compound naturally found in black pepper. Piperine enhances the absorption of curcumin by several hundred percent (72).
Omega-3 Polyunsaturated Fatty Acids
Omega-3 (n-3) polyunsaturated fatty acids (PUFA) have been studied for years regarding protective effects on health, particularly cardiovascular health, and the relationship with whole body inflammation. The prospects of n-3 PUFA use in athletes for health and performance purposes is a newer area of research (73). The most common dietary source of n-3 PUFAs is oily fish. The highest content is found in wild salmon, herring, mackerel, trout, halibut, tuna, shrimp, snapper, cod, anchovies, and sardines. The active n-3 PUFAs in fish oil are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Alpha linolenic acid (ALA) is found in plant sources such as flaxseed, walnuts, canola oil, soybean oil, soybeans, and tofu. ALA requires conversion to EPA in the body, which is a slow, inefficient process (relatively small amounts of ALA are converted to EPA and even less to DHA). People who want to consume a vegetarian source of EPA and DHA can purchase EPA and DHA derived from marine algae (74).
Specific to sport performance and recovery from training, n-3 PUFAs are thought to possess anti-inflammatory properties by enhancing membrane fluidity of skeletal muscle cells. The studies in this area thus far examine the effects of n-3 PUFAs on promoting skeletal muscle cell adaptation, enhancing energy metabolism, improving skeletal muscle recovery from training, and facilitating recovery from injury. Limited research suggests that n-3 PUFA supplementation may have a beneficial role in improving endurance performance by reducing the oxygen cost of training and in promoting recovery from eccentric contraction skeletal muscle damage. Furthermore, although not well established, some encouraging evidence demonstrates the positive effects of n-3 PUFA intake and maintenance of muscle protein synthesis rates during a period of injury (75). Promising research is examining the role of n-3 PUFAs on improving risk of developing illness and skills such as reaction time. More research is needed in this area (76)
A specific area of research in this area is examining the role, if any, of n-3 PUFAs in the prevention and treatment of traumatic brain injury and sports-related concussions (SRCs). From animal model research, evidence supports the neuroprotective effects of n-3 supplementation for both injury prevention and treatment. In humans we see reduced DHA concentration in the neurons and brain following injury. Human trials are not abundant, however, because of the ethical challenges of conducting such studies and because this area of research is new. Furthermore, SRC is not a one-size-fits-all injury (every brain injury is unique). We need more data to determine the role of n-3 PUFA supplementation for both prevention and treatment of SRCs (77).
Although we do not have enough data to make specific supplement recommendations for n-3 PUFAs for athletes, encouraging a diet rich in these compounds may be prudent for optimal health of athletes.