|If you ever wondered why you're huffing and puffing for hours after your HIIT sessions, here is the answer!|
In a recent study scientists from the Department of Kinesiology at the Ivor Wynne Centre of the McMaster University in Hamilton, Ontario (Canada), Lauren E. Skelly and colleagues tested whether this initial advantage, i.e. the increased VO2 consumption and thus energy expenditure in response to the exercise, would last 24h (Skelly. 2014).
To this ends, the researchers recruited nine healthy young men (age = 21 ± 1 years, body mass = 91 ± 15 kg) and had them perform 3 trials in random order in a repeatedmeasures design.
- The HIIT treatment involved 10 × 60-s intervals at a workload that elicited 90% HRmax with 60 s of active recovery at 50 W.
- The END protocol consisted of cycling at a workload that elicited 70% of HRmax for 50 min.
- Control protocol: No exercise was performed in the control trial (CON).
"Also, given that HIIT studies typically involve 3 training sessions per week, and given current physical activity guidelines are calling for 150 min of moderate-intensity exercise per week, a comparable END training program would consist of 3 × 50-min sessions per week." (Skelly. 2014)A 3-min warm-up at 50 W was performed prior to the main exercise bout in both, the HIIT and END trials. All trials commenced following a 10-h overnight fast (all meals were standardized for a given subject across all trials) and subjects were advised to perform no physical activity other than the prescribed exercise and normal activities of daily living for 24 h prior to each trial and over the course of the 24-h collection period.
|Figure 1: Total oxygen consumption at each measurement point (A) and over 24 h (B). CON, control; HIIT, high-intensity interval training; END, continuous moderate-intensity training; HRmax, maximal heart rate. *,p< 0.05 vs. CON; †,p< 0.05 vs. HIIT|
- Macpherson, R. E., et al. "Run sprint interval training improves aerobic performance but not maximal cardiac output." Medicine and science in sports and exercise 43.1 (2011): 115-122.
- Skelly, Lauren E., et al. "High-intensity interval exercise induces 24-h energy expenditure similar to traditional endurance exercise despite reduced time commitment." Applied Physiology, Nutrition, and Metabolism 39.999 (2014): 1-4.