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Sex or sports: what’s better for you?

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Can sex replace a cardio workout and boost your immune system?

The short answer:


Sex can be an enjoyable addition to your regular exercise routine, but it can’t replace even mild aerobic exercise and has only an indirect effect on immunity, if any.

The longer answer:


Sexual and aerobic activity can feel very similar – you’re moving, breathing heavily, feeling warm all over, and you feel a pleasant tiredness when you’re done.  But feelings can be deceiving, so let’s look at some facts.

  • Heart rate. Aerobic exercise is also known as “cardio” for a reason: during cardio, your heart rate increases, delivering more oxygen so your muscles can produce the extra energy they need to keep moving. To be in the cardio zone, your pulse needs to be at around 85% of your maximum heart rate (220 minus your age is the formula), and stay there for around 5 minutes. Even during the most active parts of sex, your heart rate rarely exceeds 130 beats per minute. By cardio standards, that’s low intensity, and workouts at this level are usually done for 40-80 minutes. During sex, the most cardio-intense phase  lasts an average of just 6 minutes
  • Breathing. Your breathing does quicken during sex, but not nearly by as much as you think. Your oxygen use during sex can be assessed using the metabolic equivalent of task (MET). MET is a unit used for measuring energy expenditure based on the ratio of oxygen consumed and weight. On average, your oxygen use during sex is 3.5 MET, while a period of intense aerobic training will reach 8.5 MET. Most importantly, heavy breathing during sex isn’t the result of physical exertion, but rather it’s the result of sexual arousal and the release of hormones like adrenaline. It’s the same reason you breathe and sweat heavily when you experience other arousal-based emotions like worry or anxiety. But feeling scared or aroused isn’t the same thing as cardio.
  • Muscles. During aerobic exercise, you engage all of the main muscle groups. Sex isn’t comparable to running or swimming when it comes to the number of muscles used or the range of motions you perform. In fact, in some positions, sex resembles a relaxation practice more than exercise. The feeling of tiredness you experience after sex? It’s not the result of muscle fatigue it’s caused by prolactin, a sleepiness hormone released after sex. This is also why sex can be a useful alternative to a sleeping aid.
  • Calories. One study found that for 30 minutes of sex, we burn 70-100 calories. In comparison, the same participants burned 213-276 calories just by walking at a moderate pace on a track. The most active phase of sex can be compared to a walk up a slight hill, but that phase is too short to affect your calorie burn significantly. It’s worth mentioning that all of the study’s participants were younger than 25. The data could look very different for other age groups.
  • Immunity. Aerobic exercise definitely improves the immune response, causing a tenfold increase in the concentration of lymphocytes (white blood cells) in the body’s airways. Sex’s effect on the immune system is not as clear. It’s possible that sex can boost immunity indirectly by improving sleep, which has a big impact on the immune system. There is also some evidence that people who regularly have sex 1-2 a week have higher levels of immunoglobulin A antibodies, which help neutralize viruses that have invaded your cells.  But the researchers conducting the study had not accounted for other possible factors, such as how active the participants are overall or their stress level, so the results aren’t entirely reliable.

There are many benefits to getting busy. Sex has been shown to reduce pain and stress thanks to endorphins, reinforce intimacy thanks to the release of oxytocin, and help you sleep better. But sexual activity is not a replacement for actual exercise. It does have one undeniable advantage: 98% of the participants in the track-walking study admitted that sex is much more fun and pleasure is the best motivation.

Welltory x Reminder, 21 Oct. 2022

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