There is more information available than ever on fitness metrics these days, given how integrated technology has become with an active lifestyle. With phones and fitness trackers providing in-depth information, there is a growing interest in knowing the effects of all fitness activity—from something as simple as a walk to as advanced as underwater swimming. This has pretty much forced people to learn how to interpret the metrics as well, including steps, stride, heart-rate or bpm, and distance. The other two terms that are returning to fitness lingo again are the aerobic and anaerobic effects of training.
Now here’s the most basic breakdown of the two terms: “Aerobic exercise involves continuous movement fueled by oxygen from the air you breathe. Anaerobic exercise involves short bursts of high-intensity movement fueled by energy stored in your muscles,” states a GoodRx.com article titled, Aerobic vs. Anaerobic Exercise: Which Benefits You More?
Aerobic means with oxygen, and anaerobic means without oxygen. The former requires the lungs and heart to keep up and supply oxygen to large muscle groups during activities that require constant motion, like walking, cycling, swimming or rowing. The latter uses energy stored in muscles to create short bursts of movement, like a sprint or any other explosive move.
Anaerobic exercises have a big advantage though, which is known as excess post-exercise oxygen consumption (EPOC). “EPOC is the result of an elevation in oxygen consumption and metabolism (Resting Energy Expenditure), which occurs after exercise as the body recovers, repairs, and returns to its pre-exercise state. This can happen for up to 24 hours, according to some sources” states the National Academy of Sports Medicine website on the science of EPOC.
This past week, after a couple of sessions of playing squash, I checked my fitness watch and saw a massive difference between two sessions in the anaerobic and aerobic metrics of the workout. The first session was 30 minutes long, and the workout report said my muscles were working faster than my heart and lungs could keep up for 42 percent of the entire game. Two days later, I played for 40 minutes: 58 percent of this was anaerobic, 21 percent was aerobic, and the rest was divided between intensive, light, and VO2 max states of breathing. Question was, was the second workout better than the first?
To reap all the benefits of a sport or a fitness programme, there needs to be a smart division to keep the body used to both aerobic and anaerobic states. Anaerobic workouts are uncomfortable—like squat jumps, for example—and if overdone, can lead to injuries and burnout, especially if you don’t set aside enough time for recovery. With aerobics, very much like in all the 1990s fitness videos you can find on YouTube, the concentration is on sustained periods of rhythmic movement, fuelled by oxygen, for longer periods.
In fact, a Runner’s World article brilliantly articulates how people fall into the trap of focussing on one rather than the other. It suggests that both are complementary. “[Aerobic] adaptations benefit anaerobic performance by facilitating faster recovery between bouts of intense exercise. Conversely, anaerobic training, which focuses on power and strength, can enhance the body's ability to generate force, leading to improved performance in both aerobic and anaerobic activities.”
Which brings us to why you feel the classic lactic acid “burn” when you workout. Delve deeper, and the science gets interesting. This is explained quite simply in a VeryWellFit.com article titled, Anaerobic Metabolism Vs. Aerobic Metabolism: “When there isn't enough oxygen in the bloodstream, glucose and glycogen cannot be fully broken down into carbon dioxide and water. Instead, lactic acid is produced, building up in the muscles and degrading muscle function.”
And what happens when excess lactic acid collects in the muscles? The reps slow down, the muscles get fatigued, and the amount of contraction it can produce goes down. When this happens, your output reduces, and this sends a signal to your brain that you have to end the set of bicep curls.
This brings us to the last bit of metabolic science worth knowing for the regular fitness goer. The body needs to produce adenosine triphosphate (ATP) for such muscle-based activity. “A glucose molecule can only produce three ATP molecules under anaerobic metabolism, while it produces 39 with aerobic metabolism,” says the same VeryWellFit.com article, and that is exactly why it is probably easier to jog for five minutes rather than do sprint for as long.
The message at the end would be that with fitness data now available to most people with a few clicks, it makes sense to know how to read it and what it actually means. The key, like always, is to balance the two amazing ways to stay fit.
Pulasta Dhar is a football commentator, podcaster and writer.