When you think of exercise, what immediately comes to mind?
Go for a run? Sweating on the stationary bike at the gym ? Or maybe carrying weight in a squat? What about a resistance band workout?
They all classify as exercise, but serve different purposes. If you want to increase your squat 1-rep max by 50 pounds, a daily cycling class won’t get you there.
It’s clear that your body adapts differently to different types of exercise , but how does that happen and what does it mean for your health?
This article will break down the benefits of the two main forms of exercise training: aerobic (commonly known as cardio) and resistance, or weight training.
What does aerobic exercise do for your health?
Aerobic, cardio, endurance – these terms all refer to exercise that simulates your heart rate and breathing rate to provide your muscles with oxygenated blood (this differs from anaerobic exercise, which we’ll discuss shortly). The energy that powers such exercise is produced in muscle cells primarily through an oxidative pathway, meaning that oxygen is required.
That explains all the heavy breathing when you go for a run, right?
That oxygen is delivered through the blood that is pumped from the heart, through the arteries, and back to the heart through the veins.
Therefore, it is clear that aerobic exercise works primarily on two systems: energy production in muscle cells and blood supply in the cardiovascular system .
You will soon learn more about the energy production system, but first you need to understand the cardiovascular adaptations that affect your health.
You probably understand that your heart is a muscle, responsible for contracting and relaxing, day after day, to pump blood throughout your body. In that way, it’s a totally unique muscle.
As long as you live, your heart will never, ever have a rest. That’s pretty amazing when you realize that all of your other muscles can rest from time to time throughout the day. But you can take steps to make sure your heart is up to the challenge .
As an analogy, consider two people: a professional football player, and a high school track athlete. They are each given a 10-pound dumbbell and told to perform 70 arm curls per minute, until their arm gives out.
You’d expect the football player to last much longer than the high school athlete – his curls are more efficient since he does them several times a week in the gym, and he’s stronger.
Similarly, aerobic exercise trains the heart to be stronger and more efficient at circulating blood. With aerobic exercise, the chamber of the heart (left ventricle) that pumps blood to the rest of the body literally gets bigger and squeezes more blood per pump , meaning your stroke volume increases.
This translates into increased cardiac output capacity, which is the amount of blood pumped by the heart per minute.
If you’ve heard of hypertrophic cardiomyopathy (enlarged heart), it may seem counterintuitive that a large left ventricular muscle is a beneficial adaptation to aerobic exercise. But, important features differentiate an enlarged left ventricle due to healthy aerobic exercise training and one resulting from disease.
A strong and efficient heart is exactly what you want to live a long and healthy life. To understand why left ventricular output , and stroke volume in particular, is so important, consider patients with chronic heart failure.
The hearts of these patients pump less blood per heartbeat than normal, which means their stroke volume is reduced. Exercise rehabilitation aims to increase the amount of blood you pump with each heartbeat , and it works.
If your heart is bigger and stronger, pumping more blood per beat, it doesn’t have to beat as fast. That’s why you often hear of elite endurance athletes with resting heart rates in their 30s and 40s. This is more important than it may seem: lower resting heart rates are associated with a lower risk of cardiovascular disease .
All these cardiac adaptations are favored by a increase in blood volume that occurs with aerobic exercise training. Without getting too technical, expanded blood volume improves the heart’s contractility and filling capacity, allowing it to pump more blood per beat .
Although the heart is a different type of muscle than the one in the arms or legs, it is still subject to a related function. It contracts in order to move blood throughout the body. In addition to making it stronger and more efficient, you can also lighten the load on your heart by lowering the resistance it faces .
Every time the heart beats, blood leaves the left ventricle into a large artery called the aorta, and then flows into a vast network of branching vessels. Every artery in the body provides resistance to the blood flowing through it that is pushed by the heart.
However, the resistance provided by the arteries is variable. Aerobic exercise training reduces the workload on the heart by reducing arterial stiffness.
When you do aerobic exercise, your heart rate increases, pushing more blood through your arteries than at rest. The inner wall of the arteries senses the increased blood flow, and through a number of mechanisms, causes the arteries to widen.
As you work out and your arteries experience this on a regular basis, they become more effective at expanding to accept every rush of blood with every heartbeat , every day. If you don’t do regular aerobic exercise, your arteries never experience this stretch and literally harden.
It’s much harder for the heart to pump blood through a rigid tube than an elastic one: imagine forcing water through a steel pipe versus a rubber tube.
If the ascending cardiac effects of improved arterial health aren’t enough to convince you that exercise is important, consider this: Increased arterial stiffness is associated with the development of coronary artery plaque, the stuff that causes heart attacks.
Aerobic exercise also affects the vascular system by promoting hair growth. Capillaries are the microscopic vessels where oxygen diffuses from red blood cells to muscle (and other) cells.
Aerobic exercise requires more oxygen delivery to the muscle to produce energy, so your body grows more capillaries to better handle energy demand. It does this by stimulating a molecule called vascular endothelial growth factor, and it’s never too late to benefit: older individuals have a similar response to younger ones.
Along with cardiovascular adaptation, aerobic exercise substantially affects the energy-producing system of the muscles. Once your blood delivers oxygen to your muscle cells, they still have to use it to produce energy that powers all the exercise you’re doing
As mentioned above, aerobic exercise relies primarily on oxidative energy production. This occurs in tiny power generators inside cells called mitochondria. Aerobic exercise also relies heavily on the breakdown of fat molecules into energy , which can only occur within the mitochondria.
Consequently, aerobic exercise training dramatically improves the ability of muscle cells to burn fat generating more mitochondria and improving their functionality. Especially in the hours following each training session, your body burns more fat than usual .
Along with increased quality and quantity of fat-burning machinery, aerobic training can increase your resting metabolic rate, resulting in more calories burned each day.
High -intensity aerobic exercise also increases excess post-exercise oxygen consumption (EPOC), resulting in increased calorie burn after training sessions, as well as what you burned while working out. While the additional expense may seem minimal at around 10-20 extra calories per hour, the cumulative effect could affect your long-term body composition goals to a great extent.
Over time, your body will adapt to the training you do. To maintain EPOC as you gain fitness , be sure to gradually progress your training intensity .
The cardiovascular and metabolic systems get all the attention when it comes to aerobic exercise, but your muscles also adapt as a result of aerobic training.
Muscles are made up of several types of fiber. Aerobic exercise training primarily influences type I fibers , also known as “slow-shifting” fibers.
They are named for the proteins within that are responsible for their contractions. Relative to type IIa (‘fast-switching’) fibers, type I fibers contract more slowly, but have a much greater ability to contract over and over again, over a sustained period of time. Perfect for aerobic exercise such as running, cross-country skiing, and cycling.
It should come as no surprise, then, that aerobic training results in primarily type I muscle fiber hypertrophy . They adapt by adding more “slow” contractile proteins.
No matter who you are, all the adaptations you just read are relevant to you. They are exactly what fuel endurance performance and cardio-metabolic health alike.
How? You saw that these adaptations reduce the risk of conditions such as heart failure, heart and vascular disease, and chronic metabolic disease. But one factor unites them all very well.
Cardiorespiratory fitness is strongly associated with the risk of all-cause mortality. Cardiorespiratory fitness is measured by maximal oxygen uptake during a stress test (also commonly known as VO2max).
VO2max is such a strong indicator of your health and mortality risk because it is determined by all of the beneficial adaptations to aerobic exercise discussed so far: the heart’s ability to pump oxygenated blood through the arteries, capillary-level blood supply, and machinery. mitochondrial to use the oxygen that the muscles receive.
Metabolic diseases are particularly associated with mitochondrial defects , which can be prevented or reversed with aerobic exercise. And the muscular adaptation mentioned? That allows you to progress your aerobic training and continue to make cardiovascular and metabolic improvements.
What does resistance exercise do for your health?
Resistance exercise is training that progressively overloads muscles to promote muscular strength, power, anaerobic endurance, and size . Traditional weightlifting, bodyweight exercises like pushups, and resistance band exercises are all examples. of resistance training aimed at making your muscles bigger, stronger, more powerful and more functional.
The specific adaptations to resistance training begin within the muscle cells. However, you will still get systemic benefits ranging from muscle growth to cardiovascular benefit.
For a deeper understanding of the full-body performance and health effects of resistance training, read how resistance exercise affects muscle at the microscopic level.
The point of resistance training is to make the muscles work more efficiently. This all begins with contractile proteins that act to control muscle shortening and lengthening.
resistance exercise , some of those proteins break down . That, along with the stress your muscle experienced, is the stimulus for your muscle to rebuild . – this time bigger, stronger, or more powerful than before.
After resistance exercise , the muscle synthesizes protein (this is aided by nutritional stimuli, i.e. protein consumption). Special cells known as satellite cells also spring into action to help build up the broken down muscle. They normally sit quietly next to muscle cells, but resistance exercise tells them to get to work.
The satellite cells combine with the muscle cells that were strained and damaged during your resistance training session. In doing so, they lend their molecular machinery to support protein synthesis that leads to muscle hypertrophy.
Regarding fiber type, resistance training with loads greater than 60% of your 1 repetition maximum results in type IIa (‘fast-change’) fiber hypertrophy. These fibers, compared to type I fibers, are capable of rapid contraction with high force, but tire more easily. That makes sense: your body adapts to meet the challenge it presents (say, lifting a difficult weight for eight reps).
Not only do type IIa fibers grow the most, but a third fiber type called IIx (previously known as IIb) can convert to IIa fibers. Type IIx fibers, before they have been converted, have properties that mix those of type I and type IIa.
These microlevel adaptations are important to athletes and the general population alike. When you make measurable gains in muscle mass, strength, or power, you can thank the protein synthesis and fiber-specific adaptations that have occurred within the muscle cells.
All of those microscopic adaptations add up to cause changes that are easier to grasp. Resistance training at the right intensity leads to measurable muscle hypertrophy.
Strength improves in part due to changes in the neuromuscular system. Control over muscles is usually a balance between competing neural signals. Some of those signals tell the muscle to contract, while others prevent contraction.
Regular resistance training can reduce the neural inhibition that normally limits muscle strength and/or endurance.
Muscle accounts for approximately 20% of resting energy expenditure , so its impact on calorie burn and body composition is significant. Not only that, but you can’t increase the mass of most other organs that account for resting energy expenditure, such as the liver, heart, brain, and kidney. Muscle is different because it hypertrophies, growing by expending more calories.
By working muscle, you not only increase strength, power, and function, but you also increase your basal metabolic rate . And by doing so, you will see an increase in your metabolism and an improvement in your health.
If you’ve ever lifted weights or done resistance exercise , you’ve probably felt your heart pounding with the effort.
Does that mean you’re getting cardiovascular and metabolic adaptations like you would with aerobic training?
Resistance exercise increases energy expenditure. But it does it differently, and to a lesser extent, than aerobic exercise.
The main sources of fuel for high-intensity weightlifting are phosphocreatine and ATP, two molecules that are readily available to fuel short, fast movements like weightlifting. This means that resistance exercise trains your energy-producing systems , but has less of an impact on your aerobic energy systems.
When it comes to cardiovascular benefits, isometric resistance training can help you maintain healthy blood pressure. Isometric exercises involve contracting your muscles against non-moving resistance , so it’s different than traditional resistance training.
To get the best of both worlds, some people turn to circuit training , which involves lifting higher reps of lighter weights and moving quickly between exercises, to maintain a higher heart rate and metabolic demand.
On a large scale and on a small scale, these adaptations to resistance exercise affect your health and physical performance. Your muscles carry you through the day, allowing you to do everything from walking up the stairs at work to picking up your two-year-old for a hug when you get home. If you are an athlete, they are essential for performance during training and on game day.
muscle through resistance training is essential to maintaining function as you age. Muscle loss even threatens some people’s ability to live independently.
In terms of body composition, muscle mass is not only an important component to maintain, but it also contributes to your resting metabolism, helping you maintain a healthy energy balance.
By now, you should have a solid understanding of what aerobic and resistance training each do. To summarize, the aerobic system causes the cardiorespiratory system to adapt. It maintains heart function and health, and keeps your energy metabolism running. Resistance training also benefits the cardiovascular system, but its role is primarily for muscle gain and function.
Aerobic or resistance training ? Which is better for fat loss?
Therefore, both aerobic and resistance exercise have enough benefits to be heralded as a “wonder drug” by some medical groups.
But what if your specific goal is to lose a few pounds of fat? Should you focus on aerobic or resistance training ?
The answer is simple: aerobic. Read on to find out why.
It’s true that resistance training that increases your skeletal muscle mass will increase your basal metabolic rate, causing you to burn a few more calories each day. But, the most substantial increase to your calorie burn will be thanks to the exercise you do.
On the other hand, aerobic exercise increases muscle’s fat-burning machinery, the mitochondria . It also burns substantially more calories per session than resistance exercise , and the results in the study indicate that ER had higher EPOC than aerobic steady state so only HIIT was similar or higher.
Most importantly, if you have fat to lose, aerobic exercise is probably more efficient for visceral and subcutaneous fat loss.
Visceral fat is the metabolically active, unsightly fat that the body stores in the abdominal cavity, which surrounds the internal organs. It’s what you should be concerned about that is associated with cardiovascular disease, diabetes, or a host of other health problems. Subcutaneous fat is what your body stores just under the skin. It is more visible, but less harmful to your health.
If you are truly after substantial fat loss, you should strongly consider adding a dietary component to your weight loss plan.
To illustrate, take a goal of 1 pound of weight loss per week. That equates to a 500-calorie deficit per day, or about an hour of moderate-intensity aerobic exercise every day of the week. Not only is it unlikely to be sustainable, but you ‘ll probably hurt yourself by taking on an intensive program like that.
To reach the same caloric deficit, you could cut 500 calories from your daily energy needs. That could simply mean reducing the portion size at each meal.
The good news is that diet and exercise go hand in hand for weight loss. When getting into a caloric deficit from both exercise and diet, neither one has to be that drastic. Instead, you can combine 250 calories of exercise with a 250-calorie reduction in energy intake each day.
Combining diet and exercise even improves your chances of maintaining your weight loss over time , and keeps your metabolism up despite your energy deficit. If that’s not enough for you, it may be better than exercise or diet alone to reduce visceral fat.
Putting it all together
Before reading, you probably already knew that exercise is key to your health and body composition. Now, you should have a much clearer idea of why that is the case .
Simply put, aerobic and resistance training tell your body to adapt in different ways. That is exactly why they cannot be substituted for each other. If cardiovascular health is your primary concern, resistance training will not result in the same blood vessel adaptations that would be received from cycling training. Likewise, you can’t expect to gain much strength or power from running. It will not signal your type IIa muscle fibers to hypertrophy!
Both are important for healthy body composition . While aerobics is better for losing fat (especially visceral fat), resistance builds muscle that keeps you going all day.
All of the adaptations you’ve read about, from strengthening the heart and making the arteries flexible, to the synthesis of muscle contractile proteins, directly affect your health and physical function. What drugs can you name that have such a widespread and profound impact?
Perhaps those scientists who call exercise a miracle drug are right.