Nutritional ergogenic aids and exercise performance
Related Editorial. Numerous ergogenic aids that claim to enhance sports performance are used by amateur and professional athletes.
Approximately 50 percent of the general population have reported taking some form of dietary supplements, while 76 to percent of athletes in some sports are reported to use them.
Physicians can evaluate these products by examining four factors method of action, available research, adverse effects, legality that will help them counsel patients.
Common ergogenic aids include anabolic steroids, which increase muscle mass.
These illegal supplements are associated with a number of serious adverse effects, some irreversible. Creatine modestly improves athletic performance and appears to be relatively safe. Dehydroepiandrosterone and androstenedione do not improve athletic performance but apparently have similar adverse effects as testosterone and are also banned by some sports organizations.
Caffeine has mild benefits and side effects and is banned above certain levels. Products that combine caffeine with other stimulants e.
Protein and carbohydrate supplementation provides modest benefits with no major adverse effects. Ergogenic aids are substances or devices that enhance energy production, use or recovery and provide athletes with a competitive advantage.
Numerous products claim to bolster strength or endurance in sports. In , approximately 50 percent of the general population reported some supplement use.
Ergogenic aids in sports pdf articles
New products with ergogenic claims appear on the market almost daily. Most are classified as supplements, which means the contents of the product and the claims on the label have not been evaluated by the U. Food and Drug Administration and may not have any scientific basis. The following questions will help the physician and patient determine whether a product is worth taking:. Are there any scientific studies published in peer-reviewed journals that support or refute the claims that the product makes?
This article reviews some of the more popular supplements and provides some basic information on others. Anabolic steroids are testosterone derivatives with three mechanisms of action. First, anticatabolic effects reverse the actions of glucocorticoids and help metabolize ingested proteins, converting a negative nitrogen balance into a positive one.
Second, anabolic effects directly induce skeletal muscle synthesis. Many early studies used physiologic doses, or doses only two to three times these amounts, and provided mixed results. More recent reviews, 5 controlling for various measurement methods, have concluded that anabolic steroids do indeed cause increased strength and muscle mass.
A randomized, double-blind, week study 6 of 40 men examined the effect of supraphysiologic testosterone doses. The participants were divided into four groups: those given a placebo with or without weight training, and those given mg testosterone enanthate with or without weight training. Diet and training times were controlled. Fat-free mass, muscle size and strength increased more than placebo in both groups taking testosterone than in the groups taking placebo.
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The subjects in the exercise plus testosterone group had a 9 percent increase in mass and 23 percent increase in bench-press strength, compared with 3 percent and 9 percent, respectively, in the subjects in the exercise plus placebo group.
Anabolic steroids have many adverse effects, most related to the unwanted androgenic effects. Some of the adverse effects are potentially serious and irreversible Table 2. Increased or decreased libido. Decreased sperm production. Scrotal pain.
Cutaneous effects. Personality disorders. Increased tramsaminases. Increased urination. Liver tumors hepatocellular carcinoma, hepatic adenoma, hepatic cholangiocarcinoma. Anabolic steroids such as testosterone and its derivatives are prescription medications with clearly defined indications. Procuring and using them without a prescription is illegal.
Most sports organizations have rules that ban the use of anabolic steroids for any reason. During brief, high intensity exercise, adenosine diphosphate is rephosphorylated to adenosine triphosphate ATP by muscle phosphocreatine stores. As muscle phosphocreatine stores become depleted, performance decreases. Oral creatine supplementation can increase muscle phosphocreatine stores by 6 to 8 percent.
Increasing the available muscle stores of phosphocreatine causes faster regeneration of ATP, allowing decreased rest time between activities and increased energy for repeated bouts of exercise. Increased muscle creatine also buffers the lactic acid produced during exercise, delaying muscle fatigue and soreness.
As with any ergogenic aid, increased motivation can spring from expected or perceived benefits, causing increased effort placebo effect. Creatine research shows generally positive results. A short-term, double-blind, placebo-controlled study 7 examined the effects of 28 days of creatine supplementation on 25 football players. Diet and exercise were tightly controlled, and strength and body composition were measured.
Body weight, dual-energy radiograph absorptiometry-scanned body mass, fat-free and bone-free mass, and bench-press strength all increased in the athletes taking creatine.
Overall lifting volume sum of all lifts was increased by 41 percent in this group. A five-week study 8 of 42 football players also showed gains in strength and mass.
Another report 9 of 19 women who took supplements for 10 weeks also described increases in strength and mass. Some researchers 10 , 11 have seen strength gains with as little as five to seven days of supplementation.
Investigations 7 , 13 of the benefits on short-term sprint performance have shown increases in endurance time. A summary of 31 studies 14 on sprint performance showed that supplemental creatine is associated with some improvement in athletic performance in laboratory settings, but most findings indicated no benefit on the field.
A typical regimen for creatine supplementation uses a loading dosage of 20 g daily, divided in four doses, for five to seven days, followed by a maintenance dosage of 5 g daily. Creatine monohydrate is not dehydrating, and may be safer. Weight gain is the most consistent adverse effect reported.
In studies that investigated side effects, no other adverse effects were found, including no changes in electrolyte concentrations, muscle cramps or strains.
Ergogenic physiological aids
Both of these supplements are precursors in the gonadal steroid pathway Figure 1. Increasing supplies of precursors theoretically cause a physiologic increase in testosterone synthesis. Dehydroepiandrosterone DHEA has been studied for its replacement role in older men and women.
These studies 16 , 17 found testosterone levels increased in women, but were unchanged in men, with no changes in body composition noted. No published studies of its ergogenic benefit in younger athletes exist. One eight-week study 18 evaluated androstenedione supplementation in 30 men, aged 19 to 29 years, during resistance training.
No differences in muscle size, strength or overall body composition were noted.
One study 19 has shown transient increases in serum testosterone levels but no ergogenic benefit has been demonstrated. No long-term studies of adverse effects are available.
If these precursors could successfully increase testosterone production, they would likely cause the many adverse effects associated with anabolic steroids. Caffeine enhances the contractility of skeletal and cardiac muscle, and helps metabolize fat, thereby sparing muscle glycogen stores. It is also a central nervous system stimulant, which can aid in activities that require concentration. Many small studies 20 , 21 using randomized, double-blind design have associated caffeine use with increased endurance times.
The smallest dose linked to positive results was mg approximately 3.
Ergogenic doses of caffeine may cause restlessness, nervousness, insomnia, tremors, hyperesthesia and diuresis. Caffeine use has no adverse effects on body temperature or sweating. Caffeine is part of a regular diet for most people and is legal to a certain level.
The ergogenic dose is approximately one half of this— to mg three cups of coffee or six to eight sodas. Many athletes take caffeine in pill form.
Sympathomimetics such as ephedrine, pseudoephedrine, phenylpropanolamine and herbal ephedrine ma huang are used for their stimulant properties.
Ergogenic Aids in Sports
A double-blind study 24 of eight patients showed prolonged time to exhaustion and decreased perception of exertion with a caffeine and ephedrine combination. Studies 24 , 25 of sympathomimetics alone have not shown benefit. The combined adverse effects of these stimulants include restlessness, nervousness, tachycardia, arrhythmias and hypertension. As of August , at least 17 deaths have been linked to use of these products in combination.
Use of ephedrine products and elevated levels of urinary caffeine, as noted above, are banned by the IOC. Protein and its constituent, amino acids, are the building blocks of muscle.
Ergogenic Aids: Counseling the Athlete
Protein supplements are used by some athletes to enhance muscle repair and growth. Inadequate protein intake does cause a negative nitrogen balance, which slows muscle growth and causes fatigue. Athletes in training have increased protein needs. A study 27 examining the protein requirements of experienced resistance-training athletes found that those consuming the recommended daily allowance for protein 0.
The protein intake required for a zero balance was 1. Another study 28 using novice resistance-training athletes found their requirements to be 1. Both studies found that protein intakes in excess of these recommendations did not provide additional gains in strength or mass. In an athlete with normal renal function, there are no notable adverse effects to increased protein consumption.
It may be more healthy, however, to avoid acquiring protein from foods that also contain increased amounts of fat and cholesterol.