Thursday, March 6, 2014

Balance, Fatigue and Carbohydrates

Over the past few years, coaches and researchers have been asking how balance affects different athletes. For sports such as gymnastics, the need for balance is obvious. In other sports like soccer, research shows that the ability to maintain balance also influences performance during cutting and changing directions. We also know that balance plays an important role in injury risk. Balance results as a response to various sensory inputs – both visual and mechanical. The central nervous system (CNS) processes this information then activates the appropriate muscles to reposition the body and/or to stabilize a joint. When the CNS cannot respond appropriately, players may fall or they may sprain or tear ligaments. Thus, a loss of balance is a key to players playing well and staying healthy. Two recent studies examined the relationship between fatigue and balance in young athletes. The first shows the extent to which fatigue disrupts balance while the second suggests that carbohydrates may be a solution to maintaining balance during a match.

In the first study, the researchers asked the question, how much does fatigue affects balance in young soccer players? Earlier studies looked at older, adult players but this is the first to focus on youth. The players were 14-15 year olds selected from competitive teams. Balance was measured by having the players stand on a pressure platform using one and two-legged stances. The pressure platform then measured “postural sway” – the degree and speed in which the athlete’s center of gravity swayed forward, backward, left and right. The greater the sway, the less balance exhibited by the player. The players did this before and after undergoing intense exercise designed to induce fatigue. For the fatigue protocol, the players were asked to go through several minutes of a moderate-intensity warm-up, and then perform six, 2 x 15 meter shuttle runs, separated by 20 seconds.

After exercise, the players’ balance was markedly disrupted. Regardless of which leg they stood on, their body swayed much more after fatigue than before. This was true for the amount of sway and how quickly they swayed to the front, back and side. In fact, the loss of balance was directly related to the degree of fatigue experienced – greater fatigue, more sway and less balance.

Similar to older, adult players, fatigue greatly affects balance in young soccer players. The authors point out that 14-15 year olds are still developing their proprioception and balance control systems. In these players, “neuromuscular immaturity”, weakness, fitness and training may also influence fatigue’s ability to disrupt balance. They go on to emphasize the role training plays in developing balance and avoiding injury in this age group.

The second study looked at young gymnasts (11-14 years old) and balance beam performance. The objective here was to determine how fatigue and a carbohydrate supplement affected the number of falls. One group of athletes underwent a warm-up followed by five sets of beam exercises. A second group participated in the warm-up plus 20 minutes of intense gymnastics training (designed to induce fatigue) before performing the five-set beam exercise. Shortly the beam routines, both groups of gymnasts were given either flavored water or a carbohydrate beverage.

As in the soccer study, fatigue affected balance by increasing the number of balance beam falls from 3.3 to 5.4 (63%). Interestingly, the carbohydrate supplement reduced falls regardless of the athlete’s level of fatigue. After intense exercise, falls were reduced to an average of 2.3. Without exercise, they were reduced to 1.9. Thus, a carbohydrate beverage can improve balance and balance beam performance in both fatigued and non-fatigued gymnasts.

What is interesting about this study is that the gymnasts did not experience a decline in blood glucose (hypoglycemia) following the intense training bout. Hypoglycemia often accompanies fatigue and can have negative effects on performance where effort, motivation or motor skill is involved. In fact, we often attribute the positive effects of carbohydrates on either prevention or reversal of hypoglycemia. In this study, hypoglycemia did not occur. Nevertheless, the researchers attributed the reduction in falls with carbohydrates to improved focus and attention.

Previously on the SSO, we’ve discussed an interesting effect of carbohydrates on athletic performance. As it turns out, players may not need to actually ingest carbohydrate drinks to gain an advantage. A “rinse and spit” method can also improve performance. That is, swishing the beverage in mouth without actually ingesting it has a psychological effect on performance by improving effort and skill. It seems that there is a link between the mouth and the brain that is somehow stimulated by carbohydrates. In fact, brain imaging studies show that just the presence of carbohydrates in the mouth activates regions of the brain involved in reward and the regulation of motor activity. This may be what affected the gymnasts’ performances. Carbohydrates in the mouth stimulated the brain and improved focus, attention and/or motor skill leading to improved balance and fewer falls.

Back to the soccer players and their balance problems with fatigue. The authors of the first study point out that neuromuscular training programs that include balance, strengthening and plyometric exercises are the best option to increase balance and reduce injury risk (as well as improve performance). This is especially true in young athletes. However, if carbohydrate beverages can improve balance and reduce falls in fatigued gymnasts, one can assume that they would do the same in fatigued soccer players. Thus, carbohydrate drinks given before and during training or matches, may be an additional tool for preventing injuries. By affecting the brain, carbohydrates may restore balance, prevent unwanted joint movements and reduce the risk of sprains, ligament tears and falls.

We’ve known for years that carbohydrate beverages provide fuel and hydration, both of which affect performance. This added benefit, linking the mouth to the central nervous system may aid in maintaining balance. To be truthful, this idea hasn’t been studied in detail. However, it is food (or drink) for thought.

References

Massimilano P, Ibba G, Attene G (2014) Fatigue-induced balance impairment in young soccer players. Journal of Athletic Training, in press, doi: http://dx.doi.org/10.4085/1062-6050-49.2.12

Batatinha HAP, et al. (2013) Carbohydrate use and reduction in number of balance beam falls: implications for mental and physical fatigue. Journal of the International Society of Sports Nutrition, 10:32.

Chambers ES, Bridge MW, Jones DA (2009) Carbohydrate sensing in the human mouth: effects of exercise performance and brain activity. Journal of Physiology, 587: 1779-1994.