Glutamine plays many important roles, including in the context of muscle growth and storage of glycogen in muscle. Although normally synthesized by the body in sufficient quantities, making it a “non-essential” amino acid, glutamine levels can become less than optimal during and after intense exercise.
In line with this, numerous studies suggest glutamine supplementation can enhance performance among athletes, especially when fatigue is a factor. Let’s look at five types of athlete that science says can benefit from supplementing with glutamine.
With fatigue, our coordination is impaired, which is reflected in, for instance, our ability to accurately throw items – problematic if you’re a basketball player! Researchers in Florida investigated the effect of L-alanyl-L-glutamine (AG), a molecule comprised of alanine and glutamine, on shooting accuracy among Division I college basketball players.
The participants played four 40-minute games, each on a different day, during which they either (1) did not drink anything, (2) drank water, (3) drank water with a low dose of AG (1 g per 500 ml), or (4) drank water with a high dose of AG (2 g per 500 ml). After, players took five shots from six different positions on the court.
Compared to water alone, there was a 11% increase in shooting accuracy after the low dose of AG. (Interestingly, a more modest increase was observed for the high dose.) This positive effect, the researchers suggest, may be due to AG promoting fluid and electrolyte uptake from the gut, benefitting nerve conduction, and, therefore, fine motor control.
A similar study, published in the Journal of the American College of Nutrition, describes the effects of AG on time to exhaustion among endurance runners.
During four separate trials, each a week apart, the participants ran for an hour at 75% of VO2 max during which they either (1) drank nothing, (2) drank an energy drink (Gatorade), (3) drank an energy drink with a low dose of AG (0.3 g per 500 ml), or (4) drank an energy drink with a high dose of AG (1 g per 500 ml). After each hour-long run, the participants ran at 90% of VO2 max until exhaustion.
Although the participants were able to run for longer in the energy drink condition (mean = 8 min, 19 s) than in the no drink condition (mean = 6 min, 8 s), the difference was not statistically significant. However, compared to the no drink condition, participants were able to run for significantly longer in the low dose (mean = 8 min, 48 s) and high dose (mean = 9 min, 22 s) conditions. The researchers speculate that this effect is due to the supplement enhancing electrolyte uptake by skeletal muscle.
Positive effects of glutamine on time to exhaustion have also been observed in cyclists.
In one study, competitive road cyclists either consumed a carbohydrate drink or a carbohydrate drink with glutamine (0.3 g per 1 kg of bodyweight) for six days. Before and after this period, they were tested on a cycle erg. Specifically, they rode at 70% of VO2 max until they could no longer maintain 50 revolutions per minute.
While those that consumed the carbohydrate drink (without glutamine) showed no improvement with respect to time to exhaustion, it took those in the glutamine condition significantly longer to reach exhaustion after supplementation (49 min, 50 s) compared to before (46 min, 33 s).
Researchers in Romania examined the effects of a high-glutamine wheat protein supplement on elite gymnasts.
The gymnasts, who undertook 4 hours of training 5 days per week, either took the supplement (1 g per 1 kg of bodyweight) or a placebo for 90 days, and were assessed on a range of parameters before and after this period.
Compared to those in the placebo condition, those who had taken the supplement showed greater increases in growth hormone, a polypeptide linked to greater muscle mass and strength, and greater decreases in creatine kinase, a marker of muscle tissue loss9. Additionally, those in the glutamine condition exhibited more substantial improvements in aerobic capacity, as measured by VO2 max.
At the professional level, soccer players typically cover 10 km per match and engage in hundreds of dynamic movements, such as sprinting, changing direction, and jumping. In few countries – if any – is soccer more popular than in Brazil, where researchers investigated the impact of glutamine supplementation on the exercise tolerance of professional players.
Thirty minutes before a fitness test, the players either consumed a carbohydrate drink or a carbohydrate drink with 3.5 g of glutamine. The test, completed on a treadmill and designed to replicate a real match, involved periods of walking, jogging, running, and sprinting, and lasted until the players reached exhaustion.
Compared to those in the carbohydrate condition, the players in the carbohydrate + glutamine condition covered, on average, an extra 2.8 km (12,750 m vs. 15,571 m), indicating that glutamine supplementation might enhance an individual’s tolerance to intermittent exercise.
Glutamine supplementation appears to be particularly valuable for delaying fatigue, ensuring that athletes can perform at a high level for longer. On one hand, this simply means athletes can keep moving, but glutamine may also enable athletes to better maintain pre-fatigue levels of coordination.
While we’ve only looked at five sports here, it’s clear these effects would be beneficial for many athletic disciplines. So, if you’re looking for a supplement to keep you going when the going gets tough, glutamine might just be it.
- Five Types of Athletes Who Benefit from Glutamine Supplementation - August 8, 2020