Rozenek, R, Salassi III, JW, Pinto, NM, and Fleming, JD. Acute cardiopulmonary and metabolic responses to high-intensity interval training protocols using 60 s of work and 60 s recovery. J Strength Cond Res 30(11): 3014-3023, 2016-Low-volume, high-intensity interval training (HIIT) consisting of 60 s work and 60 s recovery (60 s/60 s) repeated for 10 times has previously been found to produce beneficial cardiopulmonary, cellular, and metabolic adaptations in healthy and at-risk populations. There is currently relatively little information pertaining to the acute changes that take place during individual training sessions. The purpose of this study was to examine the acute physiological responses to 60 s/60 s × 10 HIIT protocols using several combinations of work and recovery intensities. Eleven healthy adults (mean age ± SD = 26.0 ± 5.3 years) performed 4 HIIT trials on separate days at varying percentages of peak power output that consisted of the following work/recovery intensities: (a) 80% PPO/0% PPO (80/0); (b) 80% PPO/50% PPO (80/50); (c) 100% PPO/0% PPO (100/0); and (d) 100% PPO/50% PPO (100/50). Compared with the other protocols, 100/50 produced higher (p ≤ 0.05) peak, average, and nadir %V[Combining Dot Above]O2peak. Other than the nadir values resulting from the 80/0 trial, all trials produced average, peak, and nadir %V[Combining Dot Above]O2peak and %HRpeak values that were within exercise intensity ranges (≈45-90% V[Combining Dot Above]O2max; ≈65-90% HRmax) recommended by the American College of Sports Medicine for improvement of cardiopulmonary function. Similar average HR and peak HR, RPE, blood lactate, and %V[Combining Dot Above]O2peak values were produced by 80/50 and 100/0 protocols. However, the average %V[Combining Dot Above]O2peak was significantly higher (∼9.3% absolute) in 80/50. It appeared that use of the 80/0, 80/50, and 100/0 protocols would be appropriate for individuals who are at the low to moderate end of the cardiopulmonary fitness spectrum.

The purpose of this study was to compare the effects of upper extremity (UE) high intensity interval training (HIIT) to UE continuous training (CT) when training at a similar intensity. 20 participants (mean age = 23 ± 3 yrs) were randomly assigned to either a HIIT (n = 10) or CT (n = 10) group. Participants completed a graded exercise test utilizing arm cranking prior to and following 6 wks (2 sessions · wk-1) of UE training. During sessions, HIIT performed 10 repetitions of 60 s of work at 92.3 ± 1.0% of the arm HRpeak (%aHRpeak) and 60 s of passive recovery (%aHRpeak = 73.0 ± 4.0%) yielding an average training intensity of 82.6 ± 1.5 %aHRpeak. CT exercised for 20 min. at an average intensity of 81.9 ± 2.2 %aHRpeak. Following training HIIT showed greater improvement in V[Combining Dot Above]O2peak compared to CT (Δ = 4.1 ml · min-¹ · kg-¹, 95%CI: 1.3 - 6.9 ml · min-¹ · kg-¹, p = .007). Total exercise time during the post-test GXT was also improved as a result of HIIT (Δ = 1.4 min, 95%CI: 0.4 - 2.3 min, p = .008). Both groups improved peak power output, but no difference was observed between them (Δ = 3.3 W, 95%CI: -3.3 - 9.9 W, p = .305). For a similar time investment, HIIT appeared to improve cardiopulmonary capacity and exercise time to a greater extent than CT and may be a time-efficient alternative for those who incorporate UE aerobic activity into a training program.