Peak heart rate responses in maximum laboratory and field tests

Background and objective: The peak heart rate (HRpeak) assessed in maximum laboratory tests has been used to determine the aerobic exercise intensity in field situations. However, HRpeak values may differ in field and laboratory situations, which can influence the relative intensity of the prescribed workloads. The objective of this study was to measure the HRpeak responses in laboratory and field maximum tests, analyzing their influence in the exercise prescription. Methods: Twenty-five physically active men aged 2151 yrs (28.9 ± 8 yrs) executed a 2,400 m field test in a running track and an individualized maximum treadmill ramp protocol. All tests were performed within two weeks, in a counterbalanced order. Before each test, the temperature and air humidity were checked, and the subjects were told no to engage in any physical activity 48 hours before. Differences between HRpeak and environmental conditions (temperature and humidity) in field and laboratory situations were respectively tested by paired and simple Student’s t tests (p < 0.05). Results: HRpeak values were significant higher in the field test than in the laboratory protocol, reaching 10 beats per minute in some cases. These differences may be partially accounted for a significant higher temperature and air humidity in the field conditions. Conclusion: In conclusion, maximum field tests seem to elicit higher HRpeak values than laboratory protocols, suggesting that the former procedures are more likely precise to determine the relative intensity of aerobic effort in physical training.