The effect of exercise on the brain should also be considered with researchers approaching this aspect of exercise from the fatigue angle, explaining that if they understood how mental fatigue relates to cognitive performance, that might shed some light on the relationship between exercise (Gutin, 1973). The role that physical activity has on different cognition abilities has been studied since the late 1800 when researchers studied the relationship between muscular tension or exertion and problem solving, mental work, and performance in general (Loeb, 1888; Golla, 1921; Newhall, 1923). In 1887 Lombard highlighted that the knee-jerk was enhanced when accompanied with mental activity, this was later reinforced with studies by Dresslar (1891) and Tuttle (1924) who used voluntary tapping with mental activity. However, research by Loeb (1888) and Lehmann (1900) found that by using a dynamometer, muscular tension is negatively correlated with mental activity. In contrast, Fere (1889) used the same dynamometer as Loeb (1888) and suggested that there was an increase in the subject's maximum squeeze by one-fourth when mental activity was induced. Researcher, Arthur Gilbert Bills in 1927 looked at the previous studies by Loeb (1888); Golla (1921); Newhall (1923); Dresslar (1891); Tuttle (1924), and Lehmann (1900) and turned his attention on examining the influence of muscular tension on the efficiency of mental work. Bills (1932) results indicated that muscular tension proved to be positively efficient as a learning condition for sense and nonsense material and improves the absolute speed and accuracy of performance in adding column digits. However, Stauffacher (1936) replicated Bills (1923) study and mentioned that muscular tension is indeed beneficial in regards to learning but only if the individual is a poor learner in terms of increased efficiency and learning abilities. In 1927 Bill conducted another study and indicated that mental fatigue results when anoxemia is induced in subjects and showed that the symptoms of mental fatigue improved by the administration of extra oxygen. Gutinn and DiGennaro (1966) suggested that these findings may be related to the fact that the highest level of coordination and control of human activity resides in the cerebral cortex and since the cortex has the highest metabolic rate in the central nervous system, it is most vulnerable to the cessation of activity due to oxygen deprivation) Gutinn and DiGennaro (1966) also suggested that cortical activity depends on precise and delicate timing which might be upset by metabolic changes in the blood. In 1973 Bernard Gutin proposed a theory, developed from Bills (1923) research and that was first introduced by Duffy (1962), that there is the relationship between exercise-induced activation and human performance which takes the form of an inverted "U" with performance optimal at some intermediate level of the between exercise-induced activation. Gutin (1973) carried out numerous studies on the relationship between mental, motor performances, and exercise or physical exertion with one study indicating that five minutes of exercise-induced activation did significantly better than the one-minute group in the speed of addition (Gutin and DiGennaro, 1968). Gutin and DiGennaro (1968) suggested that for the exercise to be effective, there is a critical level of physical exertion that must be attained with light or moderate exercise at a heart rate of about 90/120 beats per minute produced optimal mental performance. In contrast to the findings by Gatlin and DiGennaro (1968) McAdam (1967) conducted a series of studies in regards to the effect of light exercise on performance within a letter-symbol substitution task. The results showed that there were no significant differences between groups that rest or undergo light exercise between the pre-test and post test and that light exercise may not cause sufficient arousal excitation in the tissues of the organism to elicit significant differences between rest and exercise conditions.
According to Hart and Shay (1963) and Gutin (1966) there is a difference between activating the body and physical fitness. Hart and Shay (1963) define physical fitness as the ability of a person's body to meet the demands placed upon it by his work where according to Gutin (1966) physical fitness acts as activation as energy mobilization, arousal, and excitation in tissues of the organism. Gutin (1966) views link directly to the organismic theory which proposes that activity that affects the art of the organism also affects the rest of the organism (Goldstein,1995). The organismic theory was enhanced by Gutin (1973) who states that the Increases in activation brought about by physical activity result in a state of central facilitation which increases the body temperature that may increase nerve "conduction velocity". Gutin (1973) explains that the speed of the physiological responses is important to task success, however, the central nervous system gets an influx of information from cardiac, respiratory, and skeletal muscles which can increase "neural noise" and may interfere with one's ability to detect, identify and act on the relevant regulatory stimuli for the task. However, Hebb (1949) proposed that neutral integration is basically a matter of timing and a phenomenon capable of being disorganized by changes in blood chemistry that result from physical exercise. Much of the research on the relationship between exercise and cognition has tested predictions drawn from “arousal” theories (e.g., Yerkes and Dodson, 1908; Kahnemann, 1973; Humphreys and Revelle, 1984; Sanders, 1986; Hockey, Gaillard, & Coles, 1986). Common to these theories is the assumption that cognitive performance is dependent on the allocation of energetical resources to meet task demands. Davey (1973) highlighted that physical exertion affects mental performance by increasing the level of arousal but according to Lovaas (1960) the increasement of arousal interferes with learning so it is more appropriate to suggest that physical exertion affects cognitive performance by raising the level of arousal. Davey (1973); Gutin et al (1966) both hypothesised that studies have indicated an inverted "U" function and suggest that there must be a critical point, i.e., the intensity, timing, and duration of exercise must be approximately exact to produce the maximal intellectual performance. Lovaas (1960) also suggests that too high or too low levels of arousal impact the energy released from the organism influencing the organismic functioning, the optimal level that enhances performance is seen as moderate both in physical activity and levels of arousal
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