Zhaoping Li worked with a team of researchers from the University of California, Los Angeles, USA, to carry out the randomized controlled trial. She said, "The loss of exercise capacity with age often results in a reduction in physical fitness and more rapid senescence. A dietary supplement that increases exercise capacity might help to preserve physical fitness by optimizing performance and improving general health and well being in older people."
One way in which older people may reduce their exercise capacity revolves around the signaling molecule nitric oxide (NO), which is involved in many physiological processes, including those related to working out. NO production diminishes in quantity and availability as we age and is associated with an increased prevalence of other cardiovascular risk factors. In the body, NO is created from the amino acid arginine and is inactivated by oxygen free radicals. By supplementing diet with both the precursor and an anti-oxidant, the researchers hoped to support the NO system in the cyclists and thereby enhance performance.
Sixteen cyclists aged between 50 and 73 were randomly assigned to receive either the supplement or dummy placebo pills. After one week of study, the anaerobic threshold of the supplement group increased, while that of the control group did not significantly alter. This increase in anaerobic threshold was preserved at week three. According to Li, "We've demonstrated a 16.7% increase in anaerobic threshold. This indicates a potential role of arginine and antioxidant supplementation in improving exercise performance in elderly."
Arginine is abundant in many different types of foods, and your body can also make it. Arginine-rich foods include red meat, fish, poultry, wheat germ, grains, nuts and seeds, and dairy products.
Although it has been suggested that arginine may treat asthma, studies in humans have actually found that arginine worsens inflammation in the lungs and contributes to asthma symptoms. Therefore, taking arginine by mouth or by inhalation is not recommended in people with asthma.
Here's more - from the US government:
Key to grades
A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
Coronary artery disease / angina
Early evidence from several studies suggests that arginine taken by mouth or by injection may improve exercise tolerance and blood flow in arteries of the heart. Benefits have been shown in some patients with coronary artery disease and chest pain (called angina). However, more research is needed to confirm these findings and to develop safe and effective doses. B
Critical illness
Some studies suggest that arginine may be beneficial for people with critical or life-threatening illnesses when it is added to nutritional supplements. However, it is unclear what the specific role of arginine is in recovery. Because of the potential for harm, large doses of arginine should be avoided. B
Heart failure
Studies of arginine in patients with chronic heart failure have shown mixed results. Some studies report improved exercise tolerance. Additional studies are needed to confirm these findings. B
Migraine headache
Early studies suggest that adding arginine to ibuprofen (e.g., Motrin® or Advil®) therapy may decrease migraine headache pain. B
Dental pain (ibuprofen arginate)
Some research suggests that ibuprofen-arginate (Spedifen®) may reduce pain after dental surgery faster or more effectively than ibuprofen (e.g., Motrin® or Advil®) alone. More research is needed in this area. C
Diabetes (Type 1/Type 2)
Early studies in humans suggest that arginine supplements may decrease the severity of diabetes. Large, well-designed studies are needed to understand this relationship. C
Diabetic complications
Early studies in humans suggest that arginine supplements may help the body fight some long-term complications of diabetes, including heart disease and nerve damage. Well-designed studies are needed. C
Erectile dysfunction
Early studies have shown that arginine supplements may help treat erectile dysfunction (ED) in men with low nitrate levels in their blood or urine. A combination of L-arginine, glutamate, and yohimbine hydrochloride has been used to treat ED. However, because a combination product was used, and yohimbine hydrochloride is an FDA-approved therapy for this condition, the effects of arginine alone are unknown. More research is needed with arginine alone. C
Gastrointestinal cancer surgery
A combination of arginine and omega-3 fatty acids may reduce the length of hospital stays and infections after surgery in gastrointestinal cancer patients. Other research suggests that arginine, omega-3 fatty acids, and glutamine may boost the immune system and reduce inflammation after surgery. More research with arginine alone is needed.
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