Whether you love or hate cardio, any bodybuilder or coach will tell you that it’s a necessary aspect of any fat-loss plan. But what varies these days is often the athlete’s preferred method of cardio. Some swear that traditional longer, moderate-intensity sessions are best for dropping fat, while others insist that trendy high-intensity interval training (HIIT) is a better way to get the same results.
In at least one study published in the Journal of Diabetes Research, the latter was proven true. Researchers had 43 obese women follow either a HIIT plan or a moderate-intensity continuous training (MICT) for twelve weeks. The MICT sessions involved using a cycling ergometer at 60% of their respective V02 maxes, while the HIIT group did four-minute intervals with three-minute rests at 90% of their V02 maxes.
In the end, there wasn’t a notable difference between the cardio strategies when it came to losing abdominal fat. In that case, the study concluded that HIIT is a better strategy because it’s more efficient. That said, it’s not like steady-state cardio didn’t help fat loss.[RELATED1]
Another 15-week study in the Journal of Obesity had 45 women split into three groups. One group followed a HIIT-style plan, one did steady-state cardio, and one was a control. The HIIT group sprinted on a cycling ergometer for eight seconds and rested for 12 seconds, and the steady-state group cycled at 60% of their respective V02 maxes. Those doing HIIT intervals cycled for a maximum of 60 intervals (20 minutes), with the steady-state group working up to a max of 40 minutes.
Both the HIIT and steady-state plans improved cardiovascular fitness, but those who did HIIT lost significant amounts of weight and fat compared to the steady-state group. The HIIT crowd also saw improvements in insulin resistance.
Other studies have also found HIIT to improve insulin resistance and fat loss in both men and women, as a review in the Journal of Obesity points out. But it also notes that most studies have used cycle ergometers to track progress, which an average gymgoer probably wouldn’t have access to. More specific studies would be needed to find out how typical HIIT workouts like treadmill sprints or rowing machine intervals compare to longer workouts.[RELATED2]
The review also notes that despite the studies done on HIIT, research has yet to specify the ideal interval length, rest period, and overall amount of HIIT to reap the fat-loss and cardio benefits.
Aside from the lack of clarity when it comes to quantity, there’s a strong case for saving some time and knocking out a HIIT workout to get your cardio fix—but, as the name implies, HIIT is intense. Most trainers will tell you to recover for at least 24 hours and to do only two or three HIIT workouts per week. On those off days, you may want to throw in some longer cardio to balance out your cardio routine. It may be boring, but it’s a tried-and-true fitness tool.
“I’d suggest using both types [of cardio] interchangeably according to how you feel,” Yuri Feito, Ph.D., an assistant professor of exercise science at Kennesaw State University in Georgia, previously told M&F. “High-intensity training might provide greater effects in body composition over time, but it may be difficult to maintain this training regimen regularly.”[RELATED3]