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There is good reason why top-flight coaches such as Chelsea's Jose Mourinho (pictured) chew gum - because it eases stress, scientists have now claimed
For millions of football fans, the sight of an under-pressure manager furiously chewing a stick of gum while barking instructions to his players on the pitch has become a familiar one.
But according to new research, there is good reason why top-flight coaches such as Chelsea's Jose Mourinho chew gum: because it eases stress. And scientists say that the harder you chew, the greater the relief.
Just three minutes of sustained chomping can substantially lower levels of hormones associated with stress, according to a study by scientists at Tokushima University in Japan.
The study, reported in the Journal Of Prosthodontic Research, involved 20 men and women who completed a psychological stress test while their anxiety levels were assessed, by measuring their saliva for compounds associated with stress.
Immediately after the test, saliva samples were collected, and then the volunteers were told to chew flavourless gum for three minutes.
More saliva samples were taken ten minutes later and all were tested for the presence of compounds called catecholamines. These are released when a person comes under physical or emotional stress, and boost the body's ability to deal with anxiety.
Catecholamines react more quickly to stress than cortisol, and levels can be detected in saliva samples within a matter of minutes. Electrodes were also attached to the skin over the jaw muscles to assess the effort being put into the task.
Professor Andy Smith, of Cardiff University, who has carried out separate research on chewing, said: 'This interesting study shows that chewing gum can reduce stress, with the effects being seen rapidly.
'These effects were mostly seen in those who chewed most vigorously as measured by muscle tone during the study. Importantly, the researchers used an objective measure of stress – hormones from saliva – rather than self-reporting of stress.
Just three minutes of sustained chomping gum (stock image above) can substantially lower levels of hormones associated with stress, according to a study by scientists at Tokushima University in Japan
'There are a number of possible mechanisms that could underlie this effect and future research must clarify these and also examine the real-life impact of chewing gum.'
Just how chewing affects stress levels is unclear. Researchers believe the physical act of chewing increases blood flow to the brain. They suggest some parts of the brain may function differently during chewing, including the hippocampus, which is involved with emotions.
Another theory is that there is rise in heart rate during chewing, which results in more oxygen and nutrients getting to the brain. Previous research has shown that chewing gum for 20 minutes led to an increase in heart rate of 11 beats a minute.
Others say chewing leads to the production of higher levels of insulin, which in turn stimulates areas of the brain concerned with mood and memory.