9,998… 9,999… 10,000.

Oh hey! I didn’t see you there.

I was just finishing up an  exercise routine that I saw online. The internet has some great  tips for your fitness journey,   but you can’t believe everything you see there. Even this trustworthy SciShow  host did not just do 10,000 reps.

As tempting as the fitness  shortcuts you see online are,   results like these mainly come from  consistently putting in the work. But there are a few research-based  ways to level up your workouts. You should just know what’s supported  by science and what’s bogus.

So let’s burn off those myths and bulk up on the   facts to help you feel more  confident about your workout. [♪ INTRO] Exercise programs often advertise that they’ll help you “burn off that belly”  or “get rid of your arm fat.” While exercise generally is one way you  can lose weight, the literature is pretty   divided on whether doing arm day every day  will actually target the fat in your arms. Exercise affects the whole body, even when  you’re just using one group of muscles. You store energy all over,  and when you’re burning fat,   those fat molecules can be  pulled from any body part.

To test this, a team of US researchers   compared 45 men and 59 women doing  resistance training in one arm only. They used MRIs and skinfold  measurements to compare the   fat between the participants'  trained and untrained arms. The idea is that if the exercises could  really target the fat in their arms,   the trained arm would lose significantly  more fat than the untrained arm.

And that’s what happened! But only for the men, and only when they  looked at the skinfold measurements. When they looked at the MRIs, both men and women  alike seemed to have similar changes in both arms.

So even in this one study, results  were split between the ability to   target fat and all of that  being kind of make believe. The skinfold measurements might have disagreed   with the MRIs because they’re  only telling part of the story. When your muscles get bigger,   they can push on the surrounding fat and  compress the space between the fat cells.

So the same amount of fat would take up less  physical space, even though nothing was lost. This can make it look on a skinfold  measurement like there’s less fat,   when really everything is just  smooshed together a little tighter. MRIs can be a bit more revealing.

They show your fat mass throughout  the whole cross section of your arm,   regardless of the attached muscle mass. So the MRI results are seen as more  accurate, and the researchers didn’t   recommend taking any major conclusions  away from the skinfold measurements alone. But science is all about repeating trials and  testing hypotheses from a bunch of angles.

So a different study looked at 16 men and found  that they could target fat loss around their abs. In this study, one group did ab  exercises plus a 27 minute run,   and another group did only a 45  minute run with no ab exercises. Those two exercise routines take  about the same amount of energy.

All of the participants had  their body fat measured by a   highly accurate full-body  x-ray called a DEXA scan. The researchers found that while both  groups lost a similar amount of fat overall,   the group that did ab exercises lost significantly  more abdominal fat than the treadmill-only group. So the researchers concluded that  targeted fat loss is possible in men.

Which puts targeted fat loss  in the middle of the road with   some research to support it and some that doesn’t. Just note, these sample sizes are pretty low,  and comparing different populations of men and   women doing different workouts makes it  hard to draw any definitive conclusions. And trying to draw out anything more specific  than fat may prove to be even more tricky.

If you’ve ever signed up for a hot yoga class with   the promise of “sweating out the toxins  in your body,” I have bad news for you. Sweat is 99% water. The other 1% includes natural byproducts  that your body produces as a side effect   of being alive, like carbon  dioxide, urea, and salts.

Even with a full body drenched in sweat,   there’s simply not enough of those  things in your sweat to count as toxic. And when toxins do build up in your body, it’s  your liver and kidneys’ job to filter them out. Some people with heavy metal poisoning  may have more heavy metals in their sweat,   but not enough to change the fact that  you still have heavy metal poisoning.

Now, there is an exception from a 1980 study. Across 30 participants, cadmium  was released in significantly   higher concentrations in sweat than in urine. Still, that is a pretty small sample  size, and the study is a little dated.

So there’s some limited evidence  that you can sweat out those toxins,   but I wouldn’t rely on that as  your main method of poison control. And unless you’re exposed to  heavy metals on the regular,   hot yoga isn’t going to help you release  much besides water and salt... ...and stress. But there might be other reasons  to put the hot in hot yoga.

Maybe we’ve convinced you that  just the act of sweating isn’t   enough to count as a full-body cleanse. But you might choose to crank up your workout  temperature for a different reason entirely. You might have heard that hotter  environments will improve your performance.

And that may be right! There is some evidence that heat can  improve your cardiovascular health. One study published in the  International Journal of Yoga … We have a journal for everything! … found that participants who did  hot yoga showed more aerobic fitness   improvement than participants  who did room temperature yoga.

The heat probably adds a bit of extra  stress to your cardiovascular system,   which can be a good way to  improve your cardio performance. This also seems to be supported by research into  the cardiovascular benefits of sauna bathing. Just the act of basking in a hot room  could help lower your blood pressure,   reduce inflammation, and improve lung function.

So if you’re one of those people who got  the gym membership to turn over a new leaf,   but you only ever go for the sauna, it turns out  that’s not the worst thing you could be doing. There is an upper bound, though. Too hot of an environment can cause  unnecessary strain on your body.

Saunas are not recommended for people  with certain cardiovascular conditions. And extreme temperatures come at the  risk of heat stroke or heat exhaustion. But within reasonable limits, if your goal  is to improve your cardiovascular health,   exercising in the heat does  seem to have its benefits.

If you’ve ever looked at your  daily step count and breathed   a sigh of relief once that counter got  to 10,000, you’re definitely not alone. Some people will tell you that’s a kind of  magic number that’s essential for good health. And while you might not need exactly 10,000  steps, there may be something to the idea.

Getting a lot of steps in is good  for you because it moves your blood   around and keeps your bones and muscles in shape. To really put those steps to the test, a group  of researchers looked at 78,500 people in the UK. The team used data from participants who  wore a pedometer all day for seven days.

After about a seven year follow up, the  researchers analyzed the rates of cancer,   cardiovascular disease, and death in the  context of how many steps people took. They found that the more  steps per day people took,   the lower the chance of all those health problems. The best part is that there seemed to be no   minimum threshold to benefit  from getting more steps in.

Some activity is better than no activity! So 10,000 steps weren’t specifically  required in this study to see results. Which means that if that number  feels like a stretch goal for you,   you can start at a lower one  and still reap the rewards.

Another study of nearly 17,000 women found  that even those who took just 4,400 steps per day   saw significantly lower mortality rates  than those who averaged 2,700 steps a day. In fact, depending on how old  you are, 10,000 may be overkill. A meta-analysis of 15 different step-count  studies found that the actual number of   steps associated with a decreased risk  of dying anytime soon was about 7,000   steps for people aged 60 and older, and  about 9,000 steps for people under 60.

So you don’t need to get in exactly 10,000 steps,   but the fundamental idea of  getting more steps seems valid. … Though this next claim might be a step too far. There are plenty of people on  the internet who talk about   lactic acid causing soreness after a workout. First off, let’s get one thing clear: Lactic  acid does not exist in the human body.

This idea isn’t just a little wrong. It’s very wrong. Your body tissues have a pH of  around 7.4, which is basic.

So yes, scientifically speaking, ya basic. The pH of a substance is determined  by its concentration of hydrogen ions. The more hydrogen ions there are, the more acidic.

When we say that a molecule is acidic,   it means that that molecule has one  or more hydrogen ions to give away. And basic molecules tend  to pick up those hydrogens   that are oh-so-kindly donated by the acids. When you put an acidic molecule in a  basic environment, that acid will give   its hydrogen to the basic environment  and turn into its non-acidic form.

So lactic acid, which has a hydrogen to  give, donates its hydrogen to your body’s   basic environment, and then floats  around in its basic form, lactate. If you think that those two molecules  sound like potato po-tah-to, I’m sure   there will be an army of biochemists  in the comments who would disagree. And while lactic acid definitely isn’t  the thing that makes your muscles sore   after a hard run, lactate is also not the culprit.

Lactate leaves your muscles  almost as soon as it’s made,   so it doesn’t really have time to cause any pain. Here’s what really makes you feel sore: Under normal activity levels, the  energy-storing molecules called   adenosine triphosphate, or ATP, get  broken down inside your mitochondria. That breakdown of ATP releases  one hydrogen ion, which is acidic.

But the mitochondria also recycle those hydrogen  ions, so the acid doesn’t build up in your cells. The mitochondria depends on you breathing  in enough oxygen to do all of that. But when you’re exercising really hard,   your cells are using up oxygen  faster than you can breathe it in.

So in order to keep fueling your workout,   ATP has to get used up in your  muscles, outside of the mitochondria. So your body is breaking down ATP and spitting  out all those hydrogen ions into your muscles. And the more those ions build up,  the more acidic your muscles get.

That process is called metabolic acidosis,  which leads to immediate soreness. So it is an acid causing you to feel  the burn, but it isn’t lactic acid. In fact, the basic nature  of lactate helps to clear   away the excess hydrogen ions from your muscles!

And while we’re talking about sore  muscles, we’ve gotta lean into stretching. If you’re trying to prevent getting  sore muscles after a workout,   some people may recommend stretching. While it is a staple of many  warm-ups and cool downs,   there isn’t much scientific evidence  that it ultimately helps with soreness.

A couple reviews have looked at  a combined total of 17 different   studies on stretching and post-exercise  soreness, but they couldn’t find any   evidence that stretching after a  workout does much to prevent pain. And no, the type of stretching does not matter. A 2014 study randomly assigned 57 participants  to do either range-of-motion stretching like   laying on your back with one leg up  to the sky to stretch your hamstring,   static stretching like sitting toe-touches,  or no stretching after exercise.

There was no significant difference in the amount  of post-exercise soreness they experienced. So stretching probably won’t be the  answer to your workout soreness woes. In fact, it’s possible that post-exercise  stretching will make the soreness worse.

Long-term soreness is due to the microtears  that happen in your muscles when you exercise,   and stretching can worsen those tears. But maybe something more  soothing like a bath might help. Taking an icy plunge after a hard workout has  been a tool of elite athletes for a while now.

And it sounds reasonable that cold water  could help speed up muscle recovery. After all, we use ice packs  to reduce the inflammation   around minor sprains and injuries all the time. Some research has shown that elite Rugby players   can improve their jumps with a ten minute  cold plunge after a hard day of training.

And high-performance athletes struggling with  pain throughout an especially intense week   of practice may also benefit from the  pain-relieving properties of the cold. But over long periods of time, ice  baths may be counterproductive. A study from 2015 found that men who used  cold water plunges after their workouts   for 12 weeks saw significantly smaller  muscle gains than those who did not.

So reducing blood flow to your  muscles can help with the pain relief,   but that very same process  can slow down muscle growth. For now, it seems like how useful an ice  bath is depends on your level of performance,   the type of activity you do, and your goals. Our bodies, workouts, and capabilities  are all so different that it’s hard to   make a vague claim that holds true  for everyone, or even most people.

But hopefully this video helped you shed  a few fitness myths while reassuring   you about other things you may have  heard … all without breaking a sweat. Which reminds me: it’s time  to get back to my workout … 1... 2... [♪ OUTRO]