Interval Training: Two Minutes of Interval Training as Effective as 30 Minutes of Cardio

Interval Training

Two Minutes of Interval Training as Effective as 30 Minutes of Cardio

What would you rather do to get ripped?  Spend an hour on the treadmill running at a slow speed or 20 minutes doing interval training.  Interval training has a ton of benefits when compared with steady state cardio activity. It takes less time to perform interval training, and it also creates more of a metabolic demand to perform and raises metabolic rate. While the mechanisms responsible for the increase in metabolism are debated, interval training is reported to increase metabolic rate by increased glycogen resynthesis, dissipation of lactate after exercise, catecholamine-induced increases in metabolism and lipolysis, thermic effect of exercise and food, and increased muscle-protein turnover (muscle damage/repair).    However, it has been suggested that high-intensity interval training induces a larger excess postexercise oxygen consumption (EPOC) than continuous cardio because of the intense nature of the protocol.

Interval Training

In a previous study, participants performed hour-long workouts four times a week. While everyone did 40 minutes of strength training, they were divided into two groups for cardio. One group ran for 20 minutes on a treadmill and the other group performed body-weight intervals for 20 minutes. At the end of eight weeks, the interval participants lost two inches of belly fat compared to the runners who lost less than one inch. A new study published this year suggest that very short rest periods between bouts are the key to making the most out of interval training.  Researchers had cyclists do interval training for about 40 minutes twice a week for ten weeks. They combined the interval training with their regular training. Half of the cyclists did more or less classical interval training: cycling for 4.5 minutes as fast as they could and then 2.5 minutes cycling gently to recover. They repeated this cycle until the 40 minutes were up. The other half of the cyclists did a more explosive kind of interval training, with shorter cycles: they cycled as fast as they could for 30 seconds and then cycled gently for 15 seconds. They repeated this cycle for 9 minutes and then rested for 3 minutes. Then they started a second series, completing a total of 3 series.  At the end of the study, there were no differences between groups in the total volume of both HIT and low-intensity training. The short rest period group (30 seconds and then cycled gently for 15 seconds) achieved a larger relative improvement in VO2max than the longer rest period group (4.5 minutes as fast as they could and then 2.5 minutes cycling gently to recover). The cyclists who did the short rest period interval training also developed more power and were, therefore, faster. The longer rest period training, on the other hand, had little effect in this department.These results suggest that the present shorter rest interval training protocol induces superior training adaptations in both the high-power region and lower power region of cyclists’ power profile compared with a longer rest period protocol. So if you want the best gains in cardiovascular and anaerobic power from interval training, keep your rest periods short.

Researchers wanted to examine the impact of high-intensity interval exercise compared to continuous aerobic exercise.  The subjects were assigned to six weeks (3 times a week) of sprint-interval training, or continuous endurance training promotes body-fat losses despite a substantially lower training volume with sprint-interval training.  Despite substantial differences in exercise VO₂, the lasting effects of sprint interval training result in a similar total oxygen consumption over 24 hr vs. continuous aerobic exercise, indicating that the significant body-fat losses observed previously with sprint-interval training are partially due to increases in metabolism postexercise. The data demonstrate that although more O2 was consumed during the exercise bout with continuous aerobic exercise than with sprint interval  exercise, greater increases in postexercise metabolism during the rest of the day with sprint interval exercise resulted in similar total uptakes over 24 hr.  Specifically, sprint interval exercise recovery VO2 was ~50 Liters greater than in continuous aerobic exercise (~26% occurring in the first six hours postexercise and the other ~74% over the remainder of the day). Thus, over 24 hr the increased VO2 in response to sprint interval exercise in recovery completely made up the during-exercise difference versus continuous aerobic exercise.

Rønnestad BR, Hansen J, Vegge G, Tønnessen E, Slettaløkken G. Short intervals  induce superior training adaptations compared with long intervals in cyclists -An effort-matched approach. Scand J Med Sci Sports. 2015 Apr;25(2):143-51.

Hazell TJ, Olver TD, Hamilton CD, Lemon P WR. Two minutes of sprint-interval exercise elicits 24-hr oxygen consumption similar to that of 30 min of continuous endurance exercise. Int J Sport Nutr Exerc Metab. 2012 Aug;22(4):276-83.