Is cardio the right approach to fat loss and what effect does it have on our strength? What does the science say?

It seems everywhere we look cardio is the primary answer to fat loss; and, of course, cardio does play a role in overall health while promoting fat loss but we need to consider which type of cardio is right and if it is the best approach for everyone?

What is cardio exercise?

There are two basic types of exercise, aerobic and anaerobic, cardio exercise is aerobic, meaning “with oxygen” and cardio is an abbreviated term for “cardiovascular”. When performing aerobic/cardio exercise most often it consists of repeatedly moving our large muscles (arms, legs, back and abs/chest); while simultaneously increasing our heart rate. When exercising at an increased intensity we begin to breathe faster and more deeply and doing so allows us to benefit from increasing the oxygen in our blood and our bodies use oxygen more efficiently. This is important for our aerobic capacity; how well we use oxygen. When we have a high aerobic capacity our heart, lungs and blood vessels efficiently deliver large amounts of oxygen to our entire body helping our body with increased endurance when exercising. Lastly, cardio can be performed in one of two ways; Steady State or via High Intensity Interval Training or HIIT. Steady State cardio is done for longer periods at a moderate intensity, while HIIT cardio alternates between very high intensities for short bursts, and several minutes of moderate intensity before returning to high intensity.

Benefits of cardio

A good example of aerobic capacity is walking up one flight of stairs. If you reach the top feeling out of breath or notice an increase in your breathing you have a low aerobic capacity. However, if you reach the top and do not feel out of breath, you are likely fit and have a high aerobic capacity.

According to the Mayo Clinic cardio exercise as the following benefits:

  • Strengthen your heart and muscles
  • Burns more calories (than being sedentary)
  • Help control appetite
  • Boost mood through release of endorphins (feel good chemicals)
  • Help us sleep better
  • Reduces arthritis pain and stiffness via joint movement
  • Help prevent or manage high blood pressure, heart disease and diabetes

Steady State or HIIT?

It is clear that cardio exercise has significant health benefits for our overall health. However, which type, steady state or HIIT is right for you? If your goal is weight loss then steady state wins out over HIIT for several reasons (despite that HIIT burns more calories per session and has other benefits). First, when doing steady state you will recover faster. If you are spending “hours” per week doing HIIT workouts, you are forgetting a critical part of the weight loss equation which is “recovery”. As we know, the metabolic effect of doing cardio doesn’t stop after we end a cardio workout, which is good, however, the feeling of fatigue after a hard workout often continues for several days especially when we don’t recover properly. Second, and this is important for weight loss, if you combine a low calorie nutrition plan with HIIT workouts you risk loosing muscle mass, which can dramatically slow or even stop your weight loss. Third, you’ll still burn calories even when doing a moderate workout, approximately 300 calories for 30 minutes of exercise (multiplied by four sessions per week is a 1,200 calorie deficit). Forth, you’ll strengthen your aerobic capacity by exercising longer. Five, we all experience stress in our daily lives, because steady state workouts are done at a moderate intensity there is less physiological stress, which helps clear our mind and improves mood. And, consider, you are far more likely to continue working out when you aren’t pushing yourself to near aerobic failure when doing high intensity training.

The problem with too much cardio… the “interference effect”

If you are still focusing on the old school mentally that the only way to loose fat is hours of cardio, you are likely not seeing much success or if you are, you have become “skinny fat” (while you may have a thin body, you don’t have much muscle mass). Cardio alone is “not” the path to a lean body.

The most important factor in any weight loss is growing and maintaining our muscle mass. Increasing our muscle mass means our bodies’ metabolism increases and we burn more calories each day, even at rest. Ever wonder why people with muscle mass eat a lot of food? Increased muscle combined with a revived up metabolism requires more calories while still maintaining a lean body. Simply being thin, doesn’t mean you burn more calories each day and you end up reducing your calorie intake more and more just to maintain your current weight; while also increasing your cardio workouts, leaving you little time for recovery. Eventually, you reach a point of cutting so many calories you start to loose muscle mass.

So what does the “interference effect” have to do with weight loss and muscle mass? First what is the interference effect? According to the Journal of Strength and Conditioning Research, simply stated “the more cardio an individual performs… the more it interferes with muscle size and strength gains.”

“The more cardio an individual performs… the more it interferes with muscle size and strength gains.”

— Journal of Strength and Conditioning Research

As we already learned, reducing our calorie intake while doing HIIT workouts greatly increases the risk of muscle loss. Additionally, not allowing our body to recover inhibits muscle growth too. So, how do we incorporate the health benefits of cardio while growing and maintaining muscle? The easy answer, by doing the “right” cardio for your goals and/or your sport. For example, studies have shown that doing HIIT workouts reduces the risk of muscle loss because they stress our muscles (much like strength building exercises). Now you may think this contradicts what was stated above, however, it doesn’t “provided” you aren’t reducing your calorie intake while also doing HIIT workouts. If you maintain a good nutrition plan then science tells us a HIIT workout (done once or twice per week) has little impact on muscle loss when compared to steady state cardio. This is important to know so you can choose which is best for your fitness goals.

For example, if your goal is to concurrently train for increased strength and endurance you should pick an exercise that emulates your sport, this has the benefit of avoiding training that has competing adaptations. A good example is a swimmer training to improve their starts (diving from the starting block). Since a swim start is primarily focused on leg strength, doing a cardio exercise that complements that movement leads to better performance. One of the best cardio exercises for a swimmer is cycling; because, it not only strengthens the legs, but it mimics the motion of pushing off the block. Rowing is another excellent cardio workout for swimmers as it focuses on chest and arm strength.

In the same study from the Journal of Strength and Conditioning Research, it is clear that not all cardio is equal, each has it’s pros and cons. However, one of the best overall is cycling because it can be done both as a HIIT workout and a steady state workout. It also helps to reduce muscle soreness if you are focusing on an upper body strength training program. But, it’s important to make sure you not only know what type of workout is best for you but also how to implement it.

If you plan to add a HIIT workout, researchers suggest you do them on your rest day or after a weight workout to prevent reduced performance. Also, HIIT workouts should be done only once per week, but no more than twice per week to allow for proper recovery and non-interference with your primary workout program. Keep in mind that HIIT workouts are very taxing on both our mind and body therefore should be limited.

For those who prefer steady state cardio like swimming, walking, cycling, etc.; you can perform these workouts three to four times per week if you’re goal is solely weight loss and you aren’t doing strength training. If you are also doing strength training, then limit these workouts to twice per week.

Lastly, don’t get to focused on just one type of cardio, there are benefits to both and there is nothing wrong with occasionally switching it up, but, again, remember in the long run the right cardio will complement your primary workout or sport performance!

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