Effect of High-Intensity Interval Exercise on Lipid Oxidation during Postexercise Recovery.
Malatesta D, Werlen C, Bulfaro S, Cheneviegravere X, Borrani F.
Med Sci Sports Exerc. 2009 Jan 5. [Epub ahead of print]
PMID: 19127188

PURPOSE:: The aim of this study was to examine whether lipid oxidation predominates during 3 h of postexercise recovery in high-intensity interval exercise as compared with moderate-intensity continuous exercise on a cycle ergometer in fit young men (n = 12; 24.6 +/- 0.6 yr). METHODS:: The energy substrate partitioning was evaluated during and after high-intensity submaximal interval exercise (INT, 1-min intervals at 80% of maximal aerobic power output [W max] with an intervening 1 min of active recovery at 40% W max) and 60-min moderate-intensity continuous exercise at 45% of maximal oxygen uptake (C45%) as well as a time-matched resting control trial (CON). Exercise bouts were matched for mechanical work output. RESULTS:: During exercise, a significantly greater contribution of CHO and a lower contribution of lipid to energy expenditure were found in INT (512.7 +/- 26.6 and 41.0 +/- 14.0 kcal, respectively) than in C45% (406.3 +/- 21.2 and 170.3 +/- 24.0 kcal, respectively; P < 0.001) despite similar overall energy expenditure in both exercise trials (P = 0.13). During recovery, there were no significant differences between INT and C45% in substrate turnover and oxidation (P > 0.05). On the other hand, the mean contribution of lipids to energy yield was significantly higher after exercise trials (C45% = 61.3 +/- 4.2 kcal; INT = 66.7 +/- 4.7 kcal) than after CON (51.5 +/- 3.4 kcal; P < 0.05). CONCLUSIONS:: These findings show that lipid oxidation during postexercise recovery was increased by a similar amount on two isoenergetic exercise bouts of different forms and intensities compared with the time-matched no-exercise control trial

The conclusion being that HIIT isn't all it's cracked up to be? Abstract doesn't state the duration of the INT group though?

ollie wrote:The conclusion being that HIIT isn't all it's cracked up to be? Abstract doesn't state the duration of the INT group though?

Exercise bouts were matched for mechanical work output

I assume this means that output was the same.

If the SS was 45% for one hour then the output is 0.45x60 = 27

As the intervals were at 40% for 1 min and 80 for 1 min then (0.4x1 + 0.8x1) = 1.2

27 / 1.2 = 22.5 intervals = 45 minutes

That's pure guesswork BTW

Makes sense