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A study published in the British Journal of Sports Medicine examined the effects of glucosamine supplementation on functional ability and chronic knee pain in individuals with previous cartilage damage or osteoarthritis.

Subjects were randomly supplemented with either glucosamine or placebo for 12 weeks at a dose of 2,000 mg per day. Four testing sessions were conducted during the study. Changes in knee pain and function were determined by clinical and functional tests (joint line palpation, a 3 meter “duck walk,” and a repeated walking stair climb). Additionally, two different questionnaires were used to evaluate changes in pain.

The glucosamine group was found to have significantly better quality of life scores at weeks 8 and 12 than the placebo group. Based on self-report evaluations of changes during the 12 week supplementation period, 88% of the glucosamine group reported some degree of improvement in their knee pain versus only 17% in the placebo group.

These results suggest that glucosamine supplementation can provide some degree of pain relief and improved function in individuals who experience chronic knee pain due to previous cartilage damage or osteoarthritis. The results also suggest that at a dosage of 2,000 mg per day, the majority of improvements are apparent after eight weeks.

Br J Sports Med 2003 Feb;37(1):45-9

Vitamin D’s role in bone health is widely known. But the essential vitamin also plays a role in muscle and skeletal function. This connection to physical performance was expanded in a study of people over 65.

The physical performance was analyzed using a short physical performance battery (SPPB) and handgrip strength. The SPPB tests included walking speed, standing from a seated position, and maintaining balance in progressively more challenging positions.

A majority of participants were low in vitamin D. Over 28 percent of the women and 13 percent of the men were vitamin D deficient. Nearly three-fourths of the women and over half of the men had insufficient vitamin D levels.

Those with low vitamin D levels had significantly lower physical performance and grip strength than participants with adequate levels. The finding remained valid after taking into consideration other factors. They included the season of the year and physical activity levels.

With the high prevalence of vitamin D deficiency in older populations, more studies about vitamin D status and physical function are needed. Current vitamin D recommendations are based on its role in bone health. But emerging research indicates vitamin D may also play important roles in preserving muscle strength, physical function, and other aspects of health.

The Journals of Gerontology Series A: Biological Sciences and Medical Sciences 62:440-446 (2007)

Athletes deficient in B-vitamins may perform worse during high-intensity exercise and have less ability to repair and build muscle than individuals with nutrient-rich diets.

B vitamins, including thiamin, riboflavin, B6, B12, and folate, are required by the body for proper conversion of proteins and sugars into energy. B vitamins are also utilized during the production and repair of cells, including red blood cells.

In a study, researchers analyzed both diet and athletic performance of several elite and collegiate athletes, as well as those of less competitive individuals. Even a marginal deficiency in these nutrients negatively influenced the ability of the athletes’ bodies to repair, operate efficiently, and fight disease. Exercise-induced stress, changes in body tissues resulting from training, increased loss of nutrients (in sweat, urine, and feces), and the additional nutrients needed to repair and maintain higher levels of lean tissue mass may all affect an individual’s B-vitamin requirements.

The researchers noted that current national B-vitamin recommendations for active individuals may be inadequate, and chronic deficiencies could jeopardize athlete’s abilities and long-term health. Athletes, as well as individuals with poor and restricted diets, should consider a multivitamin and multimineral supplement to ensure B-vitamin adequacy.

Kathleen Woolf; Melinda M. Manore. Int J Sport Nutr Exerc Metab 2006 16:453-484.

A combination of prolonged exercise and fish oil can dramatically reduce levels of a fat that can cause hardening of the arteries, a leading cause of heart disease. Fat in the bloodstream is a primary contributor to atherosclerosis, or partial blockage of the arteries.

A study found that people who do prolonged, aerobic exercise have muscle cells that are able to quickly break down and reduce levels of a fat called triglycerides. Taking a fish oil supplement can reduce triglyceride levels even more.

The researchers studied triglyceride levels in recreationally active men after they’d eaten high-fat meals. One group ate a fatty meal after they exercised. A second group ate a high-fat meal after taking a four-gram fish oil supplement. A third group ate a high-fat meal after exercising and taking the fish oil supplement. A control group ate a high-fat meal only.

The study found a 38 percent decline in peak triglyceride levels in the men who took a fish oil supplement before they ate a high-fat meal. Peak triglyceride levels dropped 50 percent in the men who exercised and took a fish oil supplement before they ate a high-fat meal.

Regular exercise and fish oil supplements may be beneficial for people who are concerned about maintaining a healthy triglyceride level.

In a similar study, combining fish-oil supplements with regular exercise improved both body composition and heart disease risk factors. Overweight participants with various heart disease risk factors were assigned to one of three groups: Fish oil (approximately 1.9 grams/day of omega-3 fats), fish oil and exercise, or placebo (sunflower oil). The exercise group walked 3 days/week for 45 minutes. Heart disease risk factors and body composition were measured at 0, 6, and 12 weeks. The group taking fish oil had a significant reduction in triglycerides, increased HDL cholesterol, and improved arterial vasodilation (blood flow). Both fish oil and exercise independently reduced body fat.

This study showed that increasing intake of omega 3 fatty acids could be a useful addition to exercise programs aimed at improving body composition and decreasing cardiovascular disease risk.

Metabolism. 2004 Oct;53(10):1365-71.

Am J Clin Nutr. 2007 May;85(5):1267-74.

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