A team of researchers from the Catholic University of Brasilia, A Coruña University in Spain and the James Cook University in Australia has found that the level of stress in soccer referees is linked to their nervous system, but not to the physical condition as previously thought.
In the study, published in the European Journal of Applied Physiology, the researchers measured the activity of Spanish soccer referees on a normal day and on a match day.
“Our study is the first to state that referees’ stress tolerance does not depend on their specific physical condition, but on the state of their nervous system on non-match days, or the baseline condition,” said Dr. Daniel A. Boullosa, a co-author on the study and a researcher at the Catholic University of Brasilia.
The study was carried out on a total of 16 referees (11 men and 5 women), all from the Galicia Football Referee’s Association in Vigo.
“It is thanks to the Association representative’s collaboration that we were able to collect this sample,” Dr. Boullosa explained. “It is not easy to compile in one week heart activity records for these sportsmen and women on a match day over 24 hours, as well as on another day of the week, as well as carrying out the physical condition tests without them influencing the days of stress testing.”
The researchers collected the data using a cardiotachometer, which the referees wore. This technique allowed them to infer the activity of the autonomic nervous system – the sympathetic system and the parasympathetic system – and their response to stressful incidents.
“We must clarify that more beats that does not necessarily mean a greater response to stress, as it could seem. It is not a proportional relationship. This response is more closely linked to variations in the rhythm of these beats, which can be tested with mathematic calculations from their electrocardiographic records.”
The results show that the referees that felt more intense activity during the match showed a greater depression in the nervous system in the five hours that followed the match.
Researchers also observed that on match days the referees felt significant stress both in the hours before and after the match, and this response was felt even when sleeping.
“The changes observed in referees at night were of a similar level to those measured in elite athletes after maximum efforts,” Dr. Boullosa said. “Between the control day and the match day, differences of 15% to 75% were observed in the parameters studied, with the greater alterations observed in hours after the end of the match.”
The team also employed the “Yo-Yo” test to assess the physical condition. This test assesses the ability to repeat intermittent high-intensity efforts, which is a specific quality both of players and referees. There was no link found between a better physical condition shown in the tests and the ability to tolerate stress on the day of the match.
According to these results, strategies to control stress in referees should be considered, as a chronic level, associated with lower tolerance, could have negative consequences on the referees’ health, including a higher incidence of cardiovascular events.
“Their physical preparation should include, on one hand, sprinting and accelerating for their specific physical duties, whilst aerobic conditioning could be better in order to tolerate fatigue and stress on match days,” Dr. Boullosa concluded.