Washington - I am amazed by the wide range of sports nutrition products on sale in gyms. No matter the time of day, it seems gym-goers are always drinking nutrient shakes.
The sports nutrition market has grown rapidly in the UK in the past few years. In 2012 for example, it was worth about £260-million.
There are health benefit claims all over the products, including enhanced recovery, increased muscle mass, fat burning, better muscle definition and improved “well-being.”
As a sports scientist, I am often asked which ones people should consume when training. My general opinion is that supplements are unnecessary. You should be able to satisfy all your nutritional requirements with an appropriate diet.
But since this answer never seems to satisfy, here is a look at some of the most common supplements and the data on their importance to exercise. It is aimed at people who work out a few times a week.
The main reason for consuming protein is to increase muscle mass, because it stimulates the body to produce muscle protein.
The best type appears to be whey protein. It is absorbed into the gut more than 70 percent faster than other options, such as casein and soy protein supplements. This means it gets to the muscles more quickly, which increases the rate at which the body builds muscle protein.
Many gym-goers swear by the “anabolic window”, a claim that the protein needs to be consumed within minutes of stopping exercise for any gains to be realised. This is hype. The window is probably 24 to 48 hours.
As for how much protein to consume, a study found that in young men between 80kg and 85kg who weight-train regularly, it took 20 grams of whey to achieve the best possible result – what we call “maximal stimulation”. Any more leads to extra protein being excreted in the urine.
Creatine has been a popular supplement for many years, though it also occurs naturally in red meat, eggs and fish. A large body of scientific evidence supports its use to gain muscle mass and enhance recovery.
When creatine is taken up into the muscle, it helps to generate energy. This allows the muscle to contract and exercise to continue. This can help enhance gains in muscle mass and strength in response to weight training.
But creatine’s effects on sport performance are less convincing. It increases body water storage, which increases body mass.
It is often assumed that vitamins are good for health. That is true, but when vitamins are taken in excess the opposite can be true for health and exercise.
In particular vitamins C and E, which act as antioxidants, have been shown to hamper the body’s adaptation to exercise training. Two studies found that people who took large amounts of the two vitamins (1000mg/day of vitamin C and 267mg/day of vitamin E) showed no improvement in aerobic fitness or exercise performance.
This level of consumption is 250 times the recommended dietary allowance for vitamin C and 80 times that for vitamin E, though well within the range of commercially available supplements.
The study produced another important finding. Two benefits of regular exercise are that human bodies become more sensitive to insulin, meaning the person is less likely to get diabetes, and they can produce more energy by creating more of the “work horse” units in cells known as mitochondria.
The people in the study who took the vitamins found that the benefits were attenuated to some extent. This suggests that these supplements may do more harm than good, certainly in large quantities.
People consume caffeine for improved performance during a single bout of exercise, such as a competition. Taking caffeine supplements will prolong your endurance. Coffee lovers can get the same benefits from coffee consumption.
Carbohydrate-based drinks have long been seen as worthwhile because of the way they increase the delivery of energy to the body and provide hydration. But the evidence supporting their ability to improve acute exercise performance has been called into question.
While I am confident these drinks are useful during prolonged, intense exercise of about two hours, they are often consumed during shorter duration exercise when they are likely to have little benefit.
There are several other supplements available that claim to benefit exercisers. These include beta-alanine, fish oil, conjugated linoleic acid, L-carnitine, L-arginine, nitrate and vitamin D. Evidence suggests there is no apparent benefit from them.
In a study, 10 percent of supplements tested contained banned products, such as steroids. This creates the possibility of failing a drug test if exercising competitively. It is worrisome that the substances could be in health products that can be picked up in a supermarket.
In short, nutrition products can benefit people who work out, but there’s so much misinformation that you may well be wasting money or even undermining your body’s performance.
If the question is, “What supplements should I take to enhance my exercise training?” the simple answer is: nothing. Exercise, have a balanced diet and enjoy it. - Washington Post
l Stuart Gray is a senior lecturer at the Institute of Medical Sciences at the University of Aberdeen in Scotland. A version of this post first appeared on the website The Conversation.