**3. Results**

#### *3.1. Circuit Exercise Session*

Peak heart rate reached in set 1 of the circuit exercise training session was 92 ± 4% of HRmax, and was increased to 95 ± 4% of HRmax in set 2 (Table 2). Mean heart rate during the first set of the circuit exercise session was 83 ± 4% HRmax and was further increased to 89 ± 4% HRmax in set 2 (Table 2). Moreover, the time during which HR was above 80% HRmax and 90% HRmax was higher in set 2 compared with set 1 (*p* < 0.00, *d* = 1.15) (*p* < 0.001, *d* = 0.98) (Table 2). The time course of heart rate during the high-intensity circuit training session from a representative individual is shown in Figure 1.

**Table 2.** Comparison of heart rate responses during the first and the second set (set 1 and set 2) of the high-intensity circuit exercise training session.


HRmax: maximum heart rate attained during the shuttle run test.

#### *3.2. Shuttle Run Test*

1

HRmax attained during the shuttle-run test was 207 ± 5 beats per minute (bpm), while the estimated VO2max was 49 ± 3 mL/kg/min HRmax attained during the shuttle run test to exhaustion (*p* < 0.001) was 5–8% higher compared with the peak HR during set 1 and set 2 of the circuit training exercise session. However, the recovery of HR after the shuttle run test was similar to HR recovery observed in set 1 and set 2 of the circuit exercise training session (1st min: 58 ± 16 and 2nd min: 76 ± 13 bpm, *p* = 0.26 to 0.65, Table 2).
