Highs and Lows...the truth about cardio

Highs and Lows

            So many times during my workday I get asked about what types of cardiovascular exercise are the most effective. Truth is it is the same as anything else in fitness. Both types of cardio training have their value, their place, and should be incorporated in your workout schedule. Traditionally steady state cardiovascular training has been and always will be the cornerstone that all good programs are built upon. However Interval training or HITT workouts can give you benefits that cannot be ignored, especially as our lives get busy and the time we can give our fitness gets harder to come by.

No-frills, steady-state cardio benefits the vast majority of physical functions — from digestion to breathing to everyday movements like walking, standing, and sleeping — are powered by the aerobic system. “The aerobic energy pathways are the limiting factor to anything we do,” says strength coach and physical therapist Charlie Weingroff, DPT. In other words, build a better aerobic engine, and you’ll get better at everything else.

The common belief that steady state cardio can cause injury have also 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 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.

When we spend our days working in a high stress environment then hit the gym for high intensity workouts this can sometimes do more bad than good. What your body needs after a hard day is more steady state exercise that helps relieve stress and does not tax the body any further.

Critics of steady-state cardio exercise are right about a few things. It isn’t a cure-all. Beyond a low baseline level, you won’t build much strength, power, or muscle. And contrary to what many people believe, you won’t burn an appreciable amount of fat, either. Exercisers in a 2009 study conducted by researchers at Queensland University of Technology in Australia who did steady-state cardio five times a week for 12 weeks lost only 7 pounds on average — and nearly half of them lost less than 2 pounds. Steady-state cardio is also repetitive. Jog for 30 minutes and you may take as many as 5,000 steps. To some exercisers, that’s meditative; to others, it’s a bore.

It may also be risky, says sports medicine physician Jordan Metzl, coauthor of The Exercise Cure (Rodale, 2013). “The more you perform a single-movement pattern, the more you load up one area of the body, and the more likely you are to get injured.”

Still, for a low-key workout that reduces your stress level and improves recovery while delivering general health and an efficient aerobic engine, old-fashioned steady-state cardio is underrated and tough to beat.

Sprints, shuttle runs, and timed lap swimming — has been a staple among athletes for at least a century. More recently, however, casual exercisers have caught on to its benefits as well. “Back in 1992, it was understood that if you wanted to be lean and healthy, you had to do cardio — hours of it,” recalls fitness journalist Lou Schuler, coauthor ofThe New Rules of Lifting Supercharged (Avery, 2012). In the late 90’s HITT type training started to gain in popularity. “If you’re trying to lose fat, it’s pretty clear that HIIT is a more effective tool than long-distance cardio,” Robertson says. Physiologists have yet to develop a full explanation for why this is, but one reason may be the so-called after burn effect, in which the metabolism remains elevated for hours — and sometimes even days — after an intense workout. The how isn’t important for coaches like Robertson and Mike. They just know that when a client wants to lose fat fast, HIIT is one of the best tools. One 1994 study at Laval University in Quebec, Canada, found HIIT was nine times more effective for losing fat than steady-state cardio.

burning fatRegular HIIT workouts also improve your ability to withstand the rigors of other types of interval training, adds Mike. The aching sensation in your muscles that accompanies a hard sprint (which results from burning carbohydrates for fuel) becomes less intense and subsides more quickly over time, allowing you to work at a higher intensity with less rest. Your capacity to transition smoothly from  (before your workout and during rest periods) to burning carbohydrates (during your work intervals) and back again — known as your “metabolic flexibility” — improves with HIIT, as well. Together, these metabolic benefits bolster health and athletic performance, particularly in sports requiring short bursts of all-out effort interspersed with periods of reduced effort, such as basketball or martial arts. “One of the biggest misconceptions about HIIT is that it develops the aerobic system and the anaerobic system equally,” says Robertson. “But aerobic and anaerobic exercise actually place very different demands on your heart and your muscles.” Since the advent of HIIT, Robertson says he’s seen more athletes who are anaerobically fit but aerobically weak. “We’re talking Division I athletes with resting heart rates in the high 70s or low 80s” — the equivalent of a couch potatoes. “They’re fast and strong, but they gas out after just a few minutes on the field.”

Improved aerobic production can also be short term. After four to six weeks of a HITT program beginners stop seeing improvements. A steady diet of HIIT can also stimulate a near-constant flight-or-fight response from your autonomic nervous system, says Robertson, resulting in a host of anxiety-like symptoms: racing heart, sweaty palms, difficulty sleeping, and an inability to sit still or focus. Over time, this hyper vigilant state can impair recovery. “With HIIT, you have a higher probability for overreaching and , especially if you’re doing strength training as well,” Mike says. This could be a recipe for disaster in the long run and land you with some very serious injuries.

So mix it up, and choose wisely. Listen to your body and adjust your workouts to fit your day, don’t just push through an exhausting workout when the benefits you are looking for are best found in something less flashy and more peaceful. The most important tool you have in your fitness quest is your body. Learn to take care of it.