Into-the-Field Assessment of Maximal Heart Rate during Exercise

Exercise is normally recommended for its beneficial effects on health; however, exercising at very high heart rate (HR) may increase the risk of cardiac events. Theoretical maximal HR (TMHR) is subject dependent and may be easily computed through several formulas; according to the guidelines, recommended target HR range during a stress test for clinical evaluation is 50 to 85% of TMHR. Considering the new widely diffused use of wearable sensors, an into-the-field assessment of the highest HR (HHR) reached during exercise is now possible. Thus, the present study aims to assess HHR during uncontrolled exercise and to relate it to TMHR. To this aim, 178 HR series were acquired through wearable sensors from 122 athletes, while practicing 15 different sports. TMHR was assessed by applying seven well-known mathematical formulae. Percentage of athletes whose HHR overcame 85% of TMHR (i.e., recommended target HR range during a stress test) and TMHR were computed. Moreover, HHR and TMHR distributions were compared by paired T-Student test (statistical significance at 0.05). HHR of 90% or more of athletes overcame 85% of TMHR. HHR of 39% or more of athletes overcame TMHR. Thus, HHR normally approaches, and sometimes overcomes, TMHR when exercising.