Change In VO2max And Time Trial Performance To Interval Training Prescribed According To Ventilatory Threshold

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Research shows that about 20 % of participants demonstrate no change in maximal oxygen uptake (VO2max) in response to moderate intensity continuous training (MICT) (Bouchard et al 1999) or high intensity interval training (HIIT, Astorino & Schubert 2014). Approximately 50 % of this non-response is hereditary (Bouchard et al 1999) although the other 50 % is unexplored (Mann et al. 2015) and likely related to participants’ habitual physical activity and dietary patterns, sleep, and traits of the training regime. In unfit adults, Wolpern et al. (2015) showed that MICT prescribed according to Ventilatory Threshold (VT) led to lower onset of individual non-response than when prescribed using HR. PURPOSE: To prescribe HIIT according to VT to monitor aggregate and individual responses in both VO2max and time trial (TT) performance. METHODS: Eleven active (age and VO2max = 28.9 ± 7.9 yr and 38.4 ± 4.5 mL/kg/min) men and women performed baseline testing including a VO2max test on a cycle ergometer to determine peak power output (PPO) and ventilatory threshold (Caiozzo et al. 1986). Each subject also performed a 8.2 km cycling TT over three separate trials. Over a 3 wk period, they underwent 9 d of HIIT consisting of 8 – 10 60 s bouts at work rate of 130% VT with a 75 s active recovery period. Training elicited an intensity = 89.2 ± 5.7 %PPO. VO2max and TT were assessed within 96 h after training. Controls (CON) (n=6, age and VO2max = 22.7 ± 2.3 yr and 40.4 ± 8.7 mL/kg/min) consisted of active individuals who completed two sessions of baseline testing separated by 3 wk. RESULTS: Data showed a significant groupXtime interaction for VO2max (38.4 ± 4.5 mL/kg/min to 40.7 ± 4.8 mL/kg/min vs. 40.4 ± 8.7 mL/kg/min to 40.6 ± 8.7 mL/kg/min, p=0.017) and TT (923.1 ± 78.2 s to 899.4 ± 67.2 s vs. 921.2 ± 115.0 s to 924.3 114.4 s, p=0.007) between HIIT and CON. With 2Xtypical error = 0.11 L/min for VO2max and 18.0 s for TT, 63 % of participants showed meaningful increases in VO2max and TT in response to this low dose of HIIT. Two of 11 participants exhibited non-response in both variables. CONCLUSION: These preliminary data show that 9 d of HIIT at 130 %VT significantly increases VO2max and TT performance, but these responses do not occur in everyone. It is possible that the volume or duration of HIIT used is inadequate to promote greater responses in habitually active individuals.