Stress tests: physiological effects in soccer players

The human body uses stress to deal with different situations. Different types of stressors can trigger several responses that generate physiological changes. Since the Autonomic Nervous System regulates those changes, this has a special effect on athletes, because the way they deal with stress can improve or lessen their sports performance.

The effects of stress on them can be measured by monitoring heart rate, as this phenomenon is a very sensitive indicator of the state of the autonomic nervous system. The most reliable way to measure this is through cardiopulmonary stress tests.

The clinical trial "Comparison of the Cardiovascular Effects of Extreme Psychological and Physical Stress Tests in Male Soccer Players" compares the physiological and psychological effects of extreme stress tests in those sportsmen.

• In this trial participated 63 healthy second-division male soccer players, whose average ages were 25.14 ± 5.81.
• Researchers chose soccer players because it is a team sport and they wanted to analyze the interpersonal aspects that usually generate extra stress during matches.
• Two groups of participants were formed with a mean relative VO2 peak (maximum oxygen volume) of 52.14 mL/kg/min (above average n = 29 and below average n = 34).
• Other groups were also formed based on the participants' relative VO2 peak percentile. Group 1 was below the 25th percentile (48.3 mL/kg/min); group 2 was between the 25th and 50th percentiles (53.1 mL/kg/min); group 3 between the 50th and 75th percentiles (57.9 mL/kg /min). Group 4 above the 75th percentile.
• The groups were also formed considering Perna et. al's findings on the psychological stress protocol.

• The stress test was performed in a physiology laboratory.
• Participants used a treadmill to do a maximum incremental treadmill running test, with a modified Bruce protocol, i.e., 2 minutes of warm-up at a speed of 8 km/h, which was increased to 10 km/h and remained constant. The elevation was 0% during the first 3 minutes and increased by 1.5% every minute.
• A SCHILLER-Ganshorn PowerCube Ergo gas analyzer was used to measure peak VO2 values, the device was calibrated before each measurement (VO₂ peak highest 10-s, on average).
• The test ended if the player met the criteria of maximum oxygen consumption and could not continue (volitional fatigue).

The researchers compared blood pressure and HRV numbers (which they measured before and after the test).

• Compared to resting values, all heart rate parameters increased significantly after the test.
• The physical stress protocol showed a significant difference between systolic (p = 0.003) and diastolic (p < 0.001) pressure values, before and after the test (34.4 ± 15.3 mmHg, < 0.001).
• Heart rate values remained unchanged for a longer period.
• Blood pressure returned earlier to resting values.
• The difference was also significant in most parameters of the psychological stress protocol.

The level of physical demand of the players makes it essential that they undergo cardiopulmonary tests periodically to adequately monitor their condition. This allows the sports medicine physician to make the adequate recommendations to put the health of the players above their professional practice.

SOURCE: “Comparison of the Cardiovascular Effects of Extreme Psychological and Physical Stress Tests in Male Soccer Players”.