Today I want to piggyback on last week's blog post about HIIT and dive into steady-state cardio. If you haven't read either of last weeks' blog posts, I'd highly recommend you read it because it has excellent information about the mitochondria, blood sugar, and how too much HIIT can harm you.
Over the next week, I will break down the difference between steady-state and HIIT cardio, the positives, and negatives of both, and provide a general framework of how you can incorporate both into your training.
First, I want to talk about how the body adapts to exercise. It's essential to understand every individual's body will react differently, and that will determine if they are getting positive or negative results from their training.
Adaptation is ultimately what we are looking for in our training. We want our muscles to be stronger, our heart to pump more effectively, and to be less out of breath when we walk up a flight of stairs. Exercise, in the proper dosages for your body, will prompt your body to lay down more tissue to allow these changes to happen.
Exercise itself is not what makes you stronger; it's the processes that your body does afterward that make you stronger. Exercise makes you temporarily weaker. How your body recovers will dictate if you benefit from your training. So we want to make sure you're recovering properly, giving your body enough time, and not overtraining, so your time in the gym is well spent and moving you forward.
How your body adapts has to do with protein synthesis.
Protein synthesis is the process of breaking down the protein from your food into amino acids, transporting those amino acids to tissues in your body like your organs and muscles, and creating new tissue with those amino acids.
Let's specifically talk about muscle protein synthesis.
Protein degradation is the adversary process that breaks muscle tissue down. This process is always happening, and when protein synthesis is higher than protein degradation, you have more muscle. When protein synthesis equals protein degradation, you have maintenance of muscle tissue, and when protein degradation exceeds protein synthesis, you have muscle loss.
That last case is what we want to avoid with our training. Because more muscle mass, or maintaining your body's muscle mass level, is vital for many processes in your body, including your metabolism.
Protein degradation is always happening. But, it can be increased or decreased, depending on many factors, including the dosage of your cardio.
Before you exercise, you start at homeostasis, where your body is at rest or equilibrium.
When you exercise, you come to a first crossroads. Did you exercise enough to disrupt that equilibrium and "stress" your body? If yes, it triggers adaptation or change in your body's systems like your cardiovascular system and musculoskeletal system.
If you don't stress the body enough to pass the homeostasis point, you don't see any change or adaptation. But, I think this is where people get confused - they think that if they aren't dragging themselves off the floor, they didn't push it enough to see a change.
I want to challenge that any time you feel your muscles burning or your heart pumping faster than its resting point, you disrupt the equilibrium.
Once you stress your body past its equilibrium where it's comfortable, you come to a second crossroads.
Do you regularly stress your system so much that it is overwhelmed?
This partially has to do with how well your body metabolizes a stress hormone called cortisol. Some people will metabolize this very well, but many people, especially women, will overdo it on the exercise. When this happens, our nervous system is overwhelmed with the amount of circulating cortisol, which in turn, gets in the way of our body's ability to recover. More to come on this next week!
But if we can find that sweet spot, where you stress your body enough, but not so much that your system is overwhelmed, you will see desirable changes - an increase in performance, muscle, and metabolism.
No one size fits all
I always like to say that this is highly individualized. We all know that person that exercises intensely every day, and they seem to be okay. We also know that person, and maybe that person is you, that cannot tolerate any super intense exercise without feeling super tired, in pain, or suffering from sleep issues.
We want to prioritize gaining muscle (or at least maintaining it), and my philosophy is that cardio should always be seen as a bonus add-on. Cardio should not be the priority of your routine or overdone. Too much of it can blunt your protein synthesis, potentially decreasing your muscle mass and harm both your metabolism and your joints.
So, although I'll give you a framework for how to do cardio, know that this process may take some experimenting for you to figure out exactly how much is suitable for your body. Because remember, if you want to add in cardio, my philosophy is to do so conservatively. We want to avoid spiking our cortisol, blunting protein synthesis, and getting in our own way of recovering and getting stronger from our strength training sessions.
Now, let's dive into steady-state cardio.
Steady-state activity is a cardiovascular exercise that can be sustained for an extended period of time (up to one hour) like jogging, walking, biking, or an aerobics class. This does not place a high-intensity demand on the muscles, which is why it can be carried out for so long.
Within steady-state cardio, there's LISS and MISS.
LISS is low-intensity steady-state cardio. This includes walking, hiking, or leisurely bike rides where your heart rate is around 110-120 beats per minute (bpm). You can generally keep a conversation pretty easily while doing this type of exercise.
MISS is medium intensity steady-state cardio, which is usually 130-140 bpm. This heart rate range is where you land in a spin class, jogging, power walking, etc. This type of exercise should make it challenging to maintain a conversation.
So let's first talk about LISS and if and when there is a place for LISS.
This is the type of steady-state cardio that I prefer to prioritize 3-4 days/week. I like it because it's much less likely to interfere with my recovery. It's also easy on the central nervous system, unlike MISS or HIIT cardio. LISS is less likely to turn off protein synthesis and prevent you from seeing results from your strength workouts. Finally, it's easier on the joints since it's generally walking, hiking, or gentle bike rides, which tend to be less joint stress.
To me, LISS is an excellent complement to my program and my preference over MISS.
Let's get into MISS next, which is medium or moderate-intensity steady-state cardio. This includes activities like jogging, spinning, or the Stairmaster. In my opinion, doing exclusively MISS and no strength training is a mistake. So I'm always happy to hear when runners are supplementing with my strength classes.
Too much MISS can inhibit you from seeing results from your resistance training workouts. MISS can blunt our protein synthesis, which, as I talked about before, is the pathway that signals to your body to improve muscle size and strength.
When this pathway is deactivated because you have overstressed your body with too much MISS, you inhibit your body from seeing the benefits from your strength training workouts. This is when cardio can become counterproductive.
So, like most things in fitness and life, we have to strike a balance. Doing some steady-state cardio can be beneficial, but doing too much can be harmful.
In steady-state cardio, including both LISS and MISS, you are using a small percentage of your slow-twitch fibers over and over.
This is important to know because slow-twitch muscle fibers, although important, don't make up most of the size or mass of your muscles. Slow-twitch fibers are fatigue-resistant, and they are stimulated with steady-state cardio or high rep, low load type activities.
On the flipside, fast-twitch muscle fibers are the large fibers that fatigue quickly and are where we will see most of the changes in our muscle size.
We want to stimulate as many of the fibers in our muscles as possible, both fast and slow-twitch, to ultimately gain lean tissue.
If you are exclusively doing steady-state cardio, you will lose muscle mass, which will decrease your basal metabolic rate even more. Interestingly, as you participate in more steady-state cardio, your body gets more efficient at it, and you burn fewer calories than you did initially.
This is why a runner's "endurance" doesn't necessarily transition to endurance on a bike. Their body got more efficient at the motor patterns required for running.
Gaining muscle as we age is key to maintaining a healthy body.
With aging, we lose muscle, a phenomenon called sarcopenia. This causes your basal metabolic rate to decline (how many calories your body burns to keep you alive). This is why many people notice that although they eat the same amount they did in their 20's, they begin to see weight gain.
Muscle burns more calories than any tissue in the body. When you have a lot of muscle, it requires more energy to keep you alive, around 50-100 calories per pound of muscle each day! So if you gain 5 pounds of muscle, you will burn an additional 500 calories/day, even if you're not working out.
The key to improving your basal metabolic rate is to gain more muscle. As you increase your muscle mass, you can participate in more vigorous activities without compromising your joints, and in turn, you will continually improve your basal metabolic rate. This also allows you more freedom with food because your body will burn more calories, even at rest!
When you cut calories but aren't strength training, your body will decrease fat and decrease muscle, bone, and connective tissue. This lowers your basal metabolic rate (because you've lost muscle tissue), and you will have to "diet" your entire life to maintain a certain weight.
However, when you prioritize strength training, you place a high demand on your system to lay down more muscle, bone, connective tissue, and neural tissue, so the body's weight loss will come exclusively from fat. Suppose you control your nutrition by eating unprocessed foods and control insulin levels (see a nutrition specialist for information on this). In that case, you can approach a healthy body fat with lots of protective muscle.
Look out for my next post on Thursday, where I will cover the main differences between HIIT and Steady State cardio and how to find a framework for incorporating cardio for your body. Until then, check out some of our other blog posts, and I'll talk to you soon.