Posted: July 29, 2005

Science of Sport: What To Do When Your Brain Imagines Fatigue

By Owen Anderson, Ph. D. (Copyright © 2004-2005)

It is possible that your brain imagines muscular fatigue when it is not really there, manufactures muscular distress even when the muscles are fine – just to save your muscles from potentially severe damage.

The brain, you see, probably has a built-in governor which calculates the amount of time remaining before your leg muscles implode as you run either very fast or very far. Once this calculation is made, the governor then creates an overwhelming sense of conscious fatigue which forces you to slow down before the “safe time” has elapsed, sparing your cardiac and skeletal muscles – and perhaps your life (one form of exercise-related muscle breakdown – rhabdomyolysis – can be fatal). This fatigue is felt even though the muscles themselves are still operating perfectly well at a high level of effort.

Far-fetched? Not at all: Your brain is easily capable of making such calculations. Think about the last time you were a base runner during a softball game, for example. As you led off first base, the next batter rocketed the ball into the right-field corner. You sped toward second, and you somehow knew that you could make it to third (based on a “behind-the-scenes” calculation by your brain). So, you turned on the juice, and you suddenly realized – even though you were still 25 feet from second base – that you were not going to have to change strides to hit second with your foot (based on another, unconscious calculation by your grey matter). As you slid safely into third, you felt like a natural-born baseball player, since the game was coming so easily to you, with no need for conscious thinking to make great plays.

The brain makes those kinds of decisions regarding physical performance for all of us and may well monitor our intensity and duration of running and calculate when it is time to stop – or at least slow down. Just as your brain gives you a queasy stomach to let you know that you should not go on your fifth roller-coaster ride of the day (even though your stomach is actually problem-free), it may tell you that your P-R pace is just not possible on a certain day – even when your muscles are actually free of any metabolites which could slow down their functioning. It is a protective mechanism, probably selected over evolutionary time, which keeps human beings from destroying themselves during their physical pursuits. Like any protective mechanism, however, it can be a little too conservative, stopping effort when there is still a considerable amount of “gas” (performance potential) left in the tank.

If you are still a little doubtful that this can happen, consider the research which has shown that the brain can fool the body into thinking that it is exercising much more intensely than it actually is. For example, in one study individuals who were actually lifting 10- to 16-kilogram (22- to 35-pound) weights were told that they were either lifting .3- or 30-kilogram (.66- or 66-pound) resistances. When informed about their “light loads,” the weight-lifters decreased ventilation and oxygen consumption during the lifting by from 20 to 30 percent. On the other hand, suggestions of heavy exercise produced increases of 50 percent in ventilation and oxygen consumption, even though only the 10- to 16-kilo weights were being utilized (1).

It is clear from this research that the brain can create unnecessary physiological changes in competitive athletes – putting together either fatigue (and high heart rates and ventilation rates) or a sense of ease (with easy cardiac ticking and smooth breathing) for the same level of muscular effort. Since the mind can make moderate exertions feel very hard, sports psychologists, coaches, and runners have been quite interested in the concept of “positive self-talk,” since it is believed that such self-communication may at least partially “cure” the brain of its fatigue-loving ways. Positive self-talk during racing or hard training may involve the repetition of phrases such as “I’m not really tired,” “I’m going to make it,” “I can do it,” or “I’m OK – I’m just going to relax and run hard.” Many runners believe that such self-speaking can get them through “bad patches” during races and hard workouts and ultimately upgrade performances.

Of course, positive self-talk can be employed judiciously at other times (not just during tough sessions and races). For example, on the morning of a race, as one strides toward the starting line, it is better to say to oneself “I’m better than these other runners” or “I’m going to perform very well today,” compared with uttering something like “Judas – look at all of the great runners who are here.” The first two examples of self-talk may temper anxiety levels (anxiety has been linked with a heightened awareness of fatigue) and permit greater relaxation, which is associated with enhanced running economy, while the third example should heighten anxiousness and muscular tightness.

After races, positive self-talk may also play a key role. Instead of preoccupying oneself with something like “I had no guts at all in that second mile, and I really slowed down” or “I really wimped out on the third lap of the 1500,” productive self-talk might rephrase the thoughts as “I can run much better than that in the second mile of my races. I have learned from this experience and will hang in there much better in my next race” or “That was a good race. With some work on my ability to handle the third lap, I will be able to set a PR.” Post-race positive self-talk is a good way to prepare oneself for improved subsequent performances (it is certainly better than launching an attack against oneself which harms self-esteem).

How has positive self-talk actually fared in research studies? Despite the interest in self-talk in the coaching and athletic communities, the exercise-science folks haven’t exactly banged down the self-talk-and-performance door. Nonetheless, there are strong clues in the research that self-talk can be a very valuable strategy for fighting fatigue and improving overall competitiveness. In one study carried out at Wayne State University with 18 competitive male distance runners who averaged 34:10 for the 10K (2), a good correlation was noted between running economy and “private self-consciousness” (PSC), which is a measure of the degree to which individuals can turn inward and monitor body sensations and thoughts. In the Wayne-State investigation, runners who habitually directed their attention inwards were more economical than harriers who had a more-outward focus. The researchers noted that one of the factors associated with enhanced running economy (and increased PSC) was probably the employment of cognitive strategies such as positive self-talk. Enhanced economy tends to lower feelings of fatigue, since with upgraded economy any particular running pace can be managed at a lower fraction of VO2max.

In addition, research has linked “psyching-up” strategies, many of which involve some degree of positive self-talk, with heightened performance during exertions which require strength and/or endurance (3). Positive self-talk has also upgraded the performance of a soccer-shooting task among professional and semi-professional soccer players, especially when combined with goal-setting (4). Research carried out in Quebec, Canada has linked positive self-talk with improved motor performance (a heightened ability to hit a target with a dart) (5).

In a very interesting study carried out by Yannis Theodorakis (ytheo@pe.uth.gr) and his colleagues at the University of Thessaly and Democritus University of Thrace in Greece, self-talk (using the word “relax”) significantly improved basketball-shooting proficiency (6). In this research, 60 male, undergraduate, physical-education, and sport-science students were divided randomly into one control and two self-talk groups. These students were asked to shoot basketballs for three minutes, from a 4.5-meter (14.75-foot) distance to the hoop, using five different positions (specified by the researchers) on the 4.5-meter perimeter of an arc. Initially, members of all three groups received instructions to complete as many successful shots as possible in a three-minute time span.

After this three-minute trial, all 60 shooters rested for 20 minutes. During the 20-minute interlude, members of the two self-talk groups received (in private) new, specific instructions. Students in one self-talk group were asked to utter the cue-word “relax” prior to each shot at the hoop, while individuals in the second group were requested to repeat the word “fast” before every attempt at the goal. Control-group players received the same instructions utilized before the test trial (“execute as many successful shots as possible”).

The two cue words chosen by Yannis for self-talk were interesting ones. Specifically, the word “relax” is a reassuring directive often employed by athletes and recommended by sports psychologists; it is a term which often tends to improve concentration, while slowing athletes’ movements down slightly. In contrast, “fast” is a self-talk injunction which may well lead to greater quickness, perhaps at the expense of efficiency of movement and accuracy.

Following the private instructions, the three groups completed two more three-minute shooting trials, with another 20-minute recovery in between. As it turned out, there were no differences in total shots taken between the groups (self-talk had no effect on shooting frequency). However, the “relax” group sank significantly more shots in the third trial, compared with the “fast” and control subjects. Relax-group members hit 18 (out of 52) buckets in the first trial, improved to 21 (out of 53) shots in the second three-minute exam, and moved up to 24 hits (in 53 shots) for the third test. Meanwhile, control and “fast” shooters remained stuck on about 19 to 20 “makes” out of 52 to 55 attempts per trial.

This is interesting research, not just because it suggests that self-talk can enhance performance but also because it indicates that self-talk must be task-appropriate. “Fast” and “relax” might be very efficacious self-talk terms for a 3-K runner, for example, but the use of “fast” by a basketball player can lead to reduced focus and accuracy. Along similar lines, “power now” could be a great self-talk term for a 5-K runner after three kilometers of the race have been completed, but the phrase would not be as effective as “steady, smooth, relax” at the 15-mile mark of a marathon.

Taken together, the various self-talk investigations suggest that appropriate, positive self-talk leads to better muscular control and ameliorated efficiency of movement. It is important for each athlete to develop an inner dialogue which includes words and phrases which are task-relevant and which increases confidence and the ability to focus on the task at hand. The words utilized should limit anxiety and enhance concentration – and should be employed during intense training sessions as well as during competition.

The bottom line? Your brain can be a very naughty boy during hard exertion, telling you that you need to slow down when in fact your muscles do not yet require an easing of your pace. In addition, your self-talk, the dialogue you have with yourself, can have a strong impact on your performance. So, the next time you become really fatigued during a race or hard workout, remember that there may well be a strong mental component to this tiredness and that the cerebral meddlings can be at least partially overcome with a strong dose of positive self-talk. Counteract the mental slow-down game by relaxing, by avoiding the tendency to become anxious, by actually picking up your pace (running faster may activate motor units, especially collections of fast-twitch cells, which have been relatively dormant), and by judiciously employing some positive self-talk. “I’m going to make it” is always a far-better credo than “I am really getting tired” or “I’m not sure if I can do this.” ©

References

(1) “Psychogenic Factors and Exercise Metabolism: A Review,” Medicine & Science in Sports & Exercise, Vol. 17(3), pp. 309-316, 1985
(2) “The Relationships of Anxiety and Self-Attention to Running Economy in Competitive Male Distance Runners,” Journal of Sports Science, Vol. 13(5), pp. 371-376, 1995
(3) “Psyching-Up and Muscular Force Production,” Sports Medicine, Vol. 33(1), pp. 47-58, 2003
(4) “Combined Effect of Goal Setting and Self-Talk in Performance of a Soccer-Shooting Task,” Perceptual & Motor Skills, Vol. 98(1), pp. 89-99, 2004
(5) “The Effects of Positive, Negative, and Neutral Self-Talk on Motor Performance,” Canadian Journal of Sport Science, Vol. 17(2), pp. 145-147, 1992
(6) “Self-Talk in a Basketball-Shooting Task,” Perceptual & Motor Skills, Vol. 92(1), pp. 309-315, 2001

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