When it comes to our relationship with cardio, our Facebook status would read: “It’s complicated.”
Even though most of us don’t enjoy long bouts of cardio – endlessly churning on the elliptical or running for miles – we do it anyway.
Why? Maybe it’s because we think we should, in order to stay healthy or maybe to lose weight.
But have you ever paid attention to the cardio addicts at the gym? Very often, they spend hours there every week working hard, and yet their bodies don’t change.
Maybe you’ve even experienced that yourself.
Women are especially prone to falling victim to the belief that cardio is necessary. Traditional wisdom tells us that steady state cardio – when you get on a machine and go at a relatively steady pace for 30 minutes or more – is the best way to burn fat and “tone up.”
What if I were to tell you that women should never do cardio?
That’s right: I said never.
There are lots of reasons why I can confidently make this statement, in fact it’s one of my most important fitness tips, but let’s just focus on an aspect of fitness that often gets ignored …
What Steady-State Cardio Does to Your Body
Let’s take a look at the hormonal shifts that cardio forces your body to make.
1. It decreases T3.
The thyroid is both an extremely important and a largely misunderstood gland – especially when it comes to metabolism.
Of particular interest is the primary hormone T3 – more clinically called triiodothyronine. Keeping T3 levels with a healthy range is vital for both controlling and losing weight.
Unfortunately, prolonged, intense bouts of cardio do exactly the opposite. Pushing yourself through challenging and long cardio sessions can decrease your total T3 output and even potentially damage your thyroid in the long-term (2).
2. It decreases testosterone.
Now, I understand that this might sound like a good thing to women, because testosterone is considered a “male” hormone. But women are supposed to have some testosterone, as adequate levels are vital for burning fat and building muscle.
And as we’ll discover later, you need as many muscle fibers working as efficiently as possible to burn fat quickly.
Studies show that adding cardio to your routine not only decreases testosterone, but that it can also decrease thyroid stimulating hormone (TSH) which control your thyroid function (3).
That ties us back to what we just considered with T3.
3. It decreases growth hormone.
The study I cited above also found a significant decrease in Human Growth Hormone (HGH). As its name suggests, HGH stimulates the growth of new tissue, including muscle.
4. It increases cortisol.
Long cardio sessions increase levels of the stress hormone cortisol (4).
While low concentrations of cortisol let your body know that it’s time to burn up some extra fat, chronically high levels do the opposite.
When cortisol is elevated for too long, your body thinks something is wrong with the outside world, and it starts making changes to aid in your survival.
This includes storing more fat for emergency fuel and burning up some of the muscle you worked so hard to build.
Now that we’ve seen the changes that cardio can make in your hormones, what does it all mean?
Taken together, these hormonal changes mean that long, frequent cardio reduces the amount of muscle mass on your body and can even increase the amount of fat.
A Better Way to Work Out
So, if cardio is so bad, what should you do instead?
Lift weights. And not just that: You need to lift heavy weights.
You don’t need to worry about building bulky muscles. Remember how we already mentioned that women naturally have lower levels of testosterone?
Lifting weights make women look defined, not bulky.
Male bodybuilders can build big muscles because of their natural (and otherwise) levels of testosterone, along with years of specialized training and dieting.
You want to lift weights because it stimulates the growth and development of muscle fibers, which burn fat even when you’re at rest. Getting these muscles firing, then, is key to elevating your metabolism.
[Related: The #1 Cause of a Slow Metabolism]
Should women do the same workouts as men?
In short: yes. There is no reason for men and women to work out differently.
The specific exercises you should do during your workouts will depend on your goals and on what type of equipment you have available to you.
You could even get a quality workout using only your body weight. The trick is just to apply these basic principles.
The weight you use should restrict you to no more than 6 to 10 reps with perfect form, which allows you to train for hypertrophy, or muscle growth.
If you can do 11 repetitions, then you either need to add more weight or switch to more challenging exercise.
When your reps get too high for most exercises involving large muscle groups – in the 15 to 20 range – that means that your muscle fibers are not being challenged in a way that will stimulate them to grow.
Essentially, from your body’s point of view, when the reps get too high the workouts become more like cardio and not targeted for hypertrophy.
Focus on Compound Lifts
Most exercises can be divided into one of two categories: isolation or compound.
An isolation lift focuses on just one muscle group and works it all by its lonesome. A prime example of this type of exercise is a biceps curl.
Meanwhile, compound lifts work several muscles at once and generally involve a bigger, more natural movement.
Squats are kings of the compounds. Among the numerous benefits of compound exercises, they burn more calories faster and develop bigger muscle fibers, which keeps your metabolism elevated in the long-term.
Other key compound lifts include deadlifts, bench presses, bent-over rows, and shoulder presses. With these basic movements, you can effectively work your entire body.
A study published in the journal Medicine & Science in Sports & Medicine separated women into two groups – one that did just aerobics and another that did both aerobics and strength training. At the end of 12 weeks, the strength group had significantly reduced body fat, resting heart rate and blood pressure.
That’s huge. Think about it: Strength training not only improved their body composition, but their overall health.
The bottom line is that women should never do cardio for the same reason mean shouldn’t.
Say Yes to Lifting
Cardio doesn’t work the way we think it does. Long, intense cardio workouts are going to put you into a hormonal state that encourages increased fat and decreased muscle, while possibly even doing long-term damage to your metabolism.
Strength training with heavy weights, though, pretty much does exactly the opposite: making positive changes to your hormones, boosting your metabolism, and improving your overall health.
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