Steady-State Cardio Vs. High-Intensity Interval Training

Discover why a blend of both high and low-intensity exercise is the best system of cardiovascular training.

Three times a week, she gets up early, slips on her running shoes, and ventures out into the cool air, running at a strong, steady pace. If it’s cold or rainy, she heads to the gym and hops on the treadmill. The routine is always the same: 30 to 60 continuous minutes at an even speed.

Jane’s neighbor, Susan, is equally dedicated, but she gave up jogging last year in favor of something a trainer told her is more effective: Instead of trotting steadily, she sprints as hard as she can for 30 seconds, rests for a couple of minutes, and then repeats this sprint-rest cycle for 20 minutes. Sometimes, she, too, does her workouts indoors. But like Jane, she never alters the structure of those sessions — it’s always sprint, rest, repeat.

Jane and Susan are both in great shape: They look fit, and they’re lean and healthy. Lately, though, Jane’s been hearing about the benefits of high-intensity interval training and has started to wonder whether Susan’s approach may be just what she needs to kick her fitness up another notch. For her part, Susan has begun to miss her mellower workouts and questions whether slower cardio might be the ideal way to give her achy joints a chance to recover.

Both women are onto something. Though some trainers argue that steady-state cardiovascular training is inefficient, others counter that this traditional approach to cardio exercise delivers indispensable benefits you can’t get from pushing the envelope every time you work out. And although plenty of researchers have recently trumpeted the value of fast, über-intense cardio (also known as high-intensity interval training, or HIIT), in practice, many fitness professionals have found that the system has drawbacks, particularly when practiced regularly over long periods.

“The truth is that both high-intensity interval training and steady-state cardio are effective in their own ways,” says exercise physiologist Jonathan Mike, MS, CSCS, from Albuquerque.

The best system of cardiovascular training probably isn’t the all-or-nothing approach. Rather, it’s a blend of both higher and lower-intensity cardiovascular training that’s tailored to your body and your goals.


THE PLAYERS

Steady-state cardio and HIIT are convenient, versatile, and safe ways to develop your cardiovascular system. You can do them virtually anywhere with a minimum of equipment; you can switch up your activity at will (from running to swimming, say); and you don’t need a lot of coaching to do them effectively. In practice, however, the two styles of training are very different.

Steady-state cardio workouts are as simple as they come. Perform your activity at a steady, challenging-but-manageable pace (60 to 70 percent of maximal capacity) for 20 minutes or more, aiming for a heart rate of 120 to 150 beats per minute.

THE CASE FOR CARDIO

No-frills, steady-state cardio has long been a cornerstone in training programs. And with good reason. The vast majority of physical functions — from digestion to breathing to everyday movements like walking, standing, and sleeping — are powered by the aerobic system.

Even activities that are anaerobic, including HIIT, depend on the aerobic system to help restore the body to a neutral state after each work interval — and after the workout itself. (That’s why anaerobic activity makes you breathe so hard, even though the work intervals themselves require minimal oxygen.) “The aerobic energy pathways are the limiting factor to anything we do,” says strength coach and physical therapist Charlie Weingroff, DPT, creator of the DVD series Training=Rehab, Rehab=Training. In other words, build a better aerobic engine, and you’ll get better at everything else.

Several common beliefs about the dangers of steady-state cardio have recently been proven untrue. Unless you log an excessive number of hours each week doing steady-state cardio, and do little else in the way of exercise, “it doesn’t slow you down, and it doesn’t make you weak,” says Mike Robertson, MS, CSCS, co-owner of IFAST gym in Indianapolis. And people who are concerned that high-repetition cardio will wreck their knees can rest easy. In people of normal weight with healthy joints, moderate jogging can actually strengthen knees, suggests a 2011 study of lifetime runners by Monash University in Australia.

Steady-state cardio, says Robertson, also causes unique adaptations in the heart. When you exercise at a high intensity (while interval training, for example), he says, your heart often beats so fast that the left ventricle — which stores oxygenated blood momentarily before pumping it out — can’t refill completely between contractions. At a slightly lower intensity (and, thus, a lower heart rate), the left ventricle fills completely before it contracts, which causes it to grow in capacity — and thus pump more blood with each contraction — over time. This triggers your heart rate to drop substantially, both at rest and during exercise.

That’s a good thing. A lower heart rate isn’t just an indication of a healthy and high-functioning cardiovascular system. It’s also indicative of high “parasympathetic tone” in the nervous system — an enhanced ability to relax, focus, and recover from stress, including intense exercise.

“So many people these days are stressed out, on the go, can’t relax, can’t shut down,” says Robertson. “And then they go to the gym and stress their bodies more with high-intensity workouts. But what they need is more steady-state, chill-you-out workouts.”

 

 

Source: Andrew Heffernan

Susan Arruda