Dear Mark: Tweaking Sprints for a Stressful Life; Carrie’s Primal Transition

SprintFor today’s edition of Dear Mark, I answer one question and Carrie answers another. First up is one from Diane, a (full-time) working mother who’s noticed something interesting about her variable response to sprinting: when she’s relaxed and low-stress or on vacation, sprints lean her out; when she’s working and inundated with stress and responsibilities and concerns, sprints make her retain or even gain body fat. Since she realizes the power of sprinting and doesn’t want to give it up completely, Diane wants a few tips for hacking sprints on a high-stress lifestyle. Next, Carrie gives a quick overview of her transition into the Primal lifestyle and breaks down what Primal living looks like for her these days.

Let’s get into it:

Hi Mark,

I have a question about sprinting. I have been living the primal lifestyle for over 3 years now, have the food and exercise dialed, however encounter daily stresses of raising young children and full time corporate work. I incorporate sprinting once a week, however seem to retain or GAIN fat on my stomach after sprinting. When I am on vacation and relaxed, the sprints work like they are meant to and shed fat. Should I not be sprinting while leading a stressful life, as I appear to be adding cortisol to more cortisol which is leading to belly fat? I would hate to give up my sprinting as I love the other benefits they bring such as increased power and ability to chase after my children. I currently run 8 x 30 second sprints with 90 seconds recovery in between, on a track or up a hill. Is there a way to tweak my sprints so that they are not so stressful to my body.

Thanks so much,


Okay, first off: great job being cognizant of how sprints affect your body differently depending on the baseline level of stress in your life. That’s huge.

It can be disconcerting to see weight come on or stay put despite best efforts. It’s not fun to be “sensitive” to stress-related weight gain. But I actually think it’s a blessing in disguise.

Most people drift through life gaining weight here, losing weight there, eating this, exercising that way without ever putting two and two together. They’re rarely ever able to optimize their eating, exercising, and other lifestyle factors based on any real world, personable evidence. They do what someone else says – maybe me, maybe some other “expert” – and hope for the best.

Your sensitivity and your intuition allow you to spot incongruities and intolerances. You have the ability to tailor your lifestyle to your body and its requirements. You know what works for you and what doesn’t work because you notice what happens when you change a routine.

That’s rare and it’s awesome. Cherish it. Use it.

Now, some thoughts on sprinting and a stressful life.

Eight 30-second sprints with just 90 seconds of rest in between are kind of a heavy load for anyone, let alone a heavily-stressed working mother. Many of the most effective sprinting studies employ four – not eight – 30-second sprints with three to four minutes – not 90 seconds – of rest in between. And the subjects are often young college students for whom a stressful day means having to wake up before ten o’clock. Oh how I wish my life were like that again.

Traditional sprinting is far more demanding than the sprint cycling often used in exercise science. Few studies even use straight on sprinting unless the subjects are experienced athletes due to the degree of difficulty required. Sprint cycling also doesn’t really engage the upper body at all, whereas sprinting is a total body endeavor.

All that said: I’m confident you can still sprint and accrue benefits, even undergoing external stress, but you’ll have to change things up and make a few tweaks.

30 second sprints require more rest. Period. Some people may be able to handle them with truncated rest, and a carefree relaxed version of you appears to be one of those people, but a stressed-out time crunched version of you is not. Extend your rest periods to three or even four minutes instead of a minute and a half. If that’s “too easy,” you can always slowly reduce your rest as long as you’re still getting beneficial effects.

Don’t do eight of them. That’s way too many for you. They’re no joke and you don’t need to do eight of them. Heck, in one study, men and women did “just” three 30 second all-out sprint intervals on the stationary bike with 20 minutes of rest in between each sprint and they still got results. I’d say start with four and work up or down based on how you respond.

Try shorter sprints. Try 20 seconds instead of 30. Even shorter sprints work, too. In fact, a program consisting of three sets of 5 4-second treadmill sprints with 20 seconds of rest in between each sprint, done three times per week for four weeks up-regulated molecular signaling associated with mitochondrial biogenesis. More mitochondria mean greater energy production and consumption, improved substrate utilization, and overall better metabolic health. Don’t be afraid to run a series of 4-6 second sprints with minimal rest. It’ll feel “easy” compared to your normal routine but it’s still working.

If you’re going to run hills, definitely make the sprints shorter. 30 seconds of sprinting uphill is far more stressful than 30 seconds of sprinting on flat ground. Whenever I run hills, I knock my normal sprint time down. Try 15, maybe 20 seconds instead of 30. Remember, the benefits (and stresses) of sprinting depend on effort expended, not the duration.

Find the point where you start to slow down and stop there. We all have that point. Very few people on the planet can maintain top speed for 30 seconds. You probably aren’t one of them (I’m certainly not). And it’s not that continuing to run after you’ve lost your top gear isn’t useful. It is. It’s just really, really hard on the body. Since your ability to recover from stress is slightly impaired, you’ll likely do better with true sprints that stop once you start to slow down. Besides, as you get stronger, fitter, and faster (from actually recovering from the sprints now!), you’ll find that you can run a little longer at your top speed each time.

Whatever tweak you try, use your well-documented powers of observation and interpretation to determine its efficacy. Good luck!

Hi Mark,

Would love to hear more about Carrie’s background and her transition into the primal lifestyle. No offense, but as a woman it’s hard to believe doing the exact same thing a man does produces the same result. Would also be great to hear what she is doing on a daily basis.

Best to you and yours,


I stopped eating grains over a decade ago, even before we went Primal. My nutritionist at the time said I was allergic to them. I was always bloated with a pouchy stomach (despite being overall quite lean and fit) until I stopped grains and legumes completely. So when we did go full Primal, it wasn’t a big shock. The logic made sense. I was ready. I’d already been following maybe the most important aspect of Primal for a couple years so the rest just fell into place and felt completely natural.

I did not eat meat for 30 years. In the last 10 years I added in fish and just last year all other meats. I still get the majority of my protein from Primal Fuel and fish because I feel better that way. But I will say that including other meat has made me feel better, have more energy, and maintain greater muscle mass while staying leaner than ever before. I guess it doesn’t take a lot to make a difference.

And I’m not 80/20. No way, no how. The 80/20 rule definitely doesn’t work for me. When I tried it, it inadvertently became 60/40, so now I shoot for 100% and end up being 90/10. That’s important. You have to be honest with yourself and learn about your weaknesses. That’s mine: give me a little breathing room and I’ll take way too much. If I aim for perfection, I get to where I need to be. Your weakness may be something else, but you have to acknowledge and own up to it to get better.

I’ve always loved to work out and I always will. Mark and I met at the gym. Fitness was kind of our first mutual passion. It’s where we clicked. Nowadays, I actually spend way more time working out than Mark does, believe it or not! And living with Mark inspires me. I like to think I do the same for him. We keep each other on our toes.

I work out in the gym with a trainer and lift weights 3 days a week for an hour, I sprint 2 days a week (best ever exercise for my glutes and thighs), I do yoga 2-4 days a week, and I hike as well. And yes, that means 2 workouts a day some days. Didn’t I say I loved to exercise?

Vanity does come into play, no doubt about that. But exercise is also a way for me to lose myself in the moment and tap into the flow state that I think we all need to hit from time to time. Exercise is active meditation for me. If a workout is really intense, I can only focus on it and everything else melts away. And yes, even yoga is intense, just in a different way than lifting heavy weights. It takes perhaps more concentration than other forms of exercise.

Sleep is key to my feeling good. I sleep 9 hours a night and if I didn’t I doubt I’d recover from all that I do. Sleep has to come first. Most people think of sleep as an end to the day. I think of it as the beginning of my day.

After waking up, I always start with meditation, writing in a gratitude journal and reading something spiritual that inspires me. And I do this every day because with it I am in the flow all day long and life is ease and grace – even when it’s not. Even when I’m working hard and the task is difficult, my morning rituals prepare me for them. It lets me accept the task and commit to it without giving it a value like “this is unpleasant” that throws me off or makes me want to procrastinate. Then I may check emails and I’m off to workout and get on with the rest of the day.

This summer I will be doing a webinar and I will go into greater detail about how I do Primal! Then the book is coming, which will really clear things up. Thanks for writing in!


About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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58 thoughts on “Dear Mark: Tweaking Sprints for a Stressful Life; Carrie’s Primal Transition”

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  1. I always love hearing from you Carrie, it’s good to get a woman’s perspective! I also practice meditation in the mornings and keep a gratitude journal. I usually only write in it once a week, but maybe I should ramp that up a bit. I actually wrote a blog post on incorporating gratitude into life just yesterday!

  2. 30 second sprints sound crazy to me! I started out doing 8 reps of 8 second sprints on flat ground, which was right around the point where I started slowing down. Now I’m up to 12 seconds each time. I definitely feel like I’ve had a workout for days after and love the results, especially for a 10 minute workout!

  3. 30 seconds of sprinting is she covering 200 yards or what? If I did 8 of those with 90 seconds rest I would end up in the emergency room.

    She must be in phenomenal physical condition.

  4. That’s really interesting about the sprints. I quit sprinting after having done them for 6 months. I did them twice a week and saw no results at all. I would do 8 sets of 22 seconds with 1:30 rest in between. I’m usually so beat up from lifting weights that perhaps it was similar to the person who wrote in. Too much stress? Perhaps I could try sprints again and just do 4 sets of 15 second sprints once a week. Maybe cut back on the heavy squats to once a week instead of twice (once heavy, once light maybe?) I don’t know. Because I have never got the look of a healthy weight primal person, just the look of the regular old chubby me I’ve always been.

    1. You could try making that second squat session into more of a MetCon session, rather than heavy squats. Two workouts per week, one heavy lift and one MetCon might be enough especially for recovery needs.

  5. Interesting. In water aerobics we do a lot more sprints than that, and longer – up to a minute. I realize that doing them in the water is not like running up hill. But they still are hard. They pretty much wipe me out for the rest of the day.

    1. Whatever tool you use for sprinting – it should be at an intensity level that by 15 seconds you feel the pain, and by 25 seconds, you are ready to collapse. I find I can “fake” a sprint for thirty seconds, even a minute, but if I up the intensity and speed to my true max, I’m spent in 20 seconds – when it comes to sprinting, you have to be honest with yourself if your “trying” your max.

      1. Whether on a stationary bike or in the water, I do go as hard and fast as I can. It’s different from running sprints. I don’t think that you can compare them that way.

  6. Great to hear about how sprints work, and figure out I can start with shorter and fewer!

    Carrie, so great to hear about your morning meditation. That perspective you gain is inspiring. I also an inspired that you get 9 hours of sleep a night! I am always shorting myself on sleep, getting 6-7 hours, and know that more would be healthier. Hard habit to break, but I’m improving, little by little!

  7. Great to get some female perspective…not sure I will ever manage 9 hours of sleep but it’s a good reminder to prioritize sleep in whatever way possible. It’s the one thing I usually forget to consider- both as necessary for recovery as well as an indicator of overall health. Thanks for the input!

    1. My thoughts exactly! 9 hours is a lot… But then I really LOVE sleeping and feel so much better when sleeping a long night so maybe I should really prioritize this? My husband makes fun of me trying to get 8 hours every night (trying but seldom succeeding). Think I’ll have to show him this post 🙂

  8. I would LOVE to sprint, however, it’s over the top stress to even think about adding anything like that to what is already on my plate. So these two posts go hand in hand for me. Need to stop stressing about NOT sprinting so I can have some peace and move forward at whatever pace is not stressful. It will happen soon enough, I love to exercise, when it’s time I will step it up.
    Thanks both of you.

  9. “And the subjects are often young college students for whom a stressful day means having to wake up before ten o’clock.”

    Okay…you realize college is actually stressful, right? Especially for those of us who still have to work 30+ hours on top of going to class and doing homework? I’m more stressed than I’ve ever been, and if it’s going to just get worse when I graduate and join “the real world,” I may as well just throw in the towel now. Could you be a little more sensitive? This isn’t the first time you’ve written off a group of people as being lazy and spoiled.

    1. I worked a full time job overnight while going to college, and life was not that stressful. I might suggest a little more meditation or prayer, and much less sensitivity. Mark did not write anyone off.

    2. I think he’s speaking of your typical college student who does not work and is 18-22 years old. Not lazy and spoiled. Just unaware of how little responsibility and stress their lives actually have. The stress of college, even while working, doesn’t hold a candle to the stress people can have who work full time, are raising kids, own a home, or some combination of the three.

    3. Yeah, sorry, during college I worked 5-6 days/50+hrs per week and took a full course load (12-15 credit hrs) PLUS went full-time in the summer, and it doesn’t compare stress-wise to raising a 5 y/o as a single dad w/ shared custody, having a “real” job, taking care of a house, car, cooking, shopping, etc. Not even close.

      College – even though a lot of my TIME was spoken for – was probably one of the least stressful times of my life because in the scheme of things, stuff that happens in one’s 20’s don’t generally have life-and-death consequences.

      Stuff I do now does, and there’s actually another human being who depends on me to live. Big difference, I’d say.

    4. College can be an exceptionally stressful event in one’s life. I chose to forego college, and entered the workplace immediately (also a stressful event).
      I admit jealousy of my friends who, as freshmen and sophomores were able to start their day at 10am or finish at 2pm or 3pm, but fully realize that for many that was an exceptional thing. Most of the people who did have short school days were also stuck with a full(if they were lucky), or multiple work shifts to help pay for school.
      I think it’s fair to say that we each have our own unique experiences that can seem more or less stressful than someone else’s given our unique circumstances at any given time in life.

    5. I was horribly stressed out in college too, but my responsibility to OTHERS was much, much less. There’s a big difference. There’s also the fact that college students are young, and their bodies can deal with stress better. Even while practically having a nervous breakdown, I could exercise like a fiend with zero negative repurcussions. Give it a couple of decades, and you’ll know what Mark was getting at. No need to feel slighted.

  10. Sprints – very interesting indeed! I’ve been trying to focus on what is prompting the belly fat and hadn’t thought about this aspect in particular.

    I’ve been having a very stressful 6 months or so with family issues just as we reintroduced some sprinting (and sleep as been poorer … definitely raised cortisol potential when I add it all together). For us we use stationary bikes twice a week and have built up to 10 x 30 secs with 90 second rests. On the bike of course it takes about 10-12 seconds to get up to all out pace so equates to less than 30 and of course as Mark mentions biking is less ‘demanding’ overall than run sprinting. However, tweaking down might be in order, or lengthening the intervals. What we did notice though was once we got out on the MTBs recently we found hills much easier than we normally would at the beginning of riding outdoors again.

    Carrie, can’t wait for the book! I too have built a meditative routine on waking, in the last 5 weeks or so, as finding the space and motivation at the end of the day doesn’t work for me. At 7 am I spend 30 minutes in qigong standing followed by some yogic breathing and ohms (I blend qigong and yoga which are from very much the same ‘space’), It definitely sets a different tone for the day.

    I used to spend much more time exercising (IM triathlete – 20 plus lunatic hours a week) than I do now, but reading your weekly schedule has me hanker for a little more again!

    Sleep, yes, I reckon 8-9 hours would make my life a whole lot better, but, although now into retirement living, and there are no time-constraints, I simply don’t sleep for more than an hour or three at a stretch and am lucky to accumulate more than 6-7 broken hours each night. This I know is hormonally stressful and makes for fat retention issues and appetite dysfunction.

    When I crack the sleep issue I reckon everything will fall into place!

  11. Thanks for the glimpse into your world, Carrie! Your take on the 80/20 rule was an eye-opener–that’s me too, except I didn’t really realize it so explicitly until I read that. The meditative start to the day is inspiring too.

  12. I keep meaning to work sprints into my plan. LIfting weights just takes it out of me, but I also struggle with 10 pounds or so that comes and goes. This article and the comments make me think it’s time to work those sprints in after all. I’ll have to take it pretty slow at first, I’m definitely not conditioned for sprints at this stage.

  13. Great post about the sprints Mark! I’m living a similar stressful lifestyle as a single mom of two young kids and a full time corporate job. I lift heavy 3-4 days a week and have been wanting to incorporate sprints (to improve body composition) also but didn’t think I could find the time. I’m happy to know that shorter, fewer sprints will still give me a benefit.

    …”a program consisting of three sets of 5 4-second treadmill sprints with 20 seconds of rest in between each sprint…” Actually, it sounds like I could achieve this level of sprinting by playing tag with my 10 year old on the playground ;-).

  14. I’m still working to find my flow. I know I have a ways yet to go, but how far that is and where it will take me is still unknown (but hopefully will be quite exciting, nonetheless!).

    I appreciate Carrie’s perspective as well, as even a man can gain insight from a woman’s perspective. I know I have learned a lot from some of the women in my life. The possibility of adding yoga has occurred, but I need to work on my time management before adding much else in to the existing routines. I would like to say that Carrie’s description of working out being an active meditation struck me. I’ve known that since I learned I enjoy exercising, one of the reasons was the mental relief I experienced because I tend not to focus on anything but the workout. I hadn’t thought to express it as active meditation, but I’ll remember that (and it may help me stick to workouts better than ever before)!

    I envy the acuity Diane has acquired/cultivated (and which Mark pointed out) and hope to do the same for myself. I love sprinting myself; so much. I just began doing them again (on Saturday morning!) after beginning to shift momentum forward again in my own primal journey.

  15. So, what about someone who sprints on an elliptical? I’ve been doing 30 second sprints with longer rest periods (3 to 4 minutes) and do 4 to 6 sprints. I turn the resistance way up and just go as fast as I possibly can for 30 seconds. Like Diane, I haven’t seen any results. I never feel sore so it’s hard to imagine I’m really over-doing anything. I’m about to give up on sprints and exercise in general since I hate doing it and my weight isn’t changing at all.

    1. It may be sprints in combination with heavy lifting (rarely but regularly) and frequent low-level activity. When I first tried my hand at primal and healthier lifestyle, I did the exact same…sprinting on a machine (although mine was the treadmill) and I would go anywhere from 30 to even 90 seconds sprinting with similar rest periods (I guess I was way overdoing it!) but I was quite active at the time, so I think some of the improved tone came from all-around efforts. However, I cannot deny how good I felt after sprints (fortunately enough for me) and I have to believe it helped.

      Perhaps you can try what Mark suggested…20-second sprints with the same rest and stick with 4 to see if you notice a difference and increase duration, resistance, or number of sprints depending on how you feel your body is responding). I’m definitely picking them back up again but for shorter duration)

    2. For me, the way the elliptical is set up I just can’t do an effective sprint on it. I can move faster, but it’s not a sprint. Why not try a bike or the track? And I wouldn’t turn the resistance all the way up on the bike because then it’s not a sprint but a strength exercise.

    3. I’ve never used an eliptical but I have a spinner bike in my home office. Fifteen to twenty minutes on that using interval training ( HIT) and my legs are shot. When I’m in full out sprint I’m practically in tears it’s so intense. The results are pretty profound. My size, definition and strength have gone way up. My guess it that either an eliptical doesn’t allow for the intensity you need or you are holding back because your tolerance level for pain is low. Personally, I get off on the “burn” from intense exercise but I know people who have an aversion to it and so their gains are minimal.

  16. I’m with Carrie on the 80/20 thing. After 3 1/2 years primal, I know that, for me, “cheating” leads to ongoing cheating and my healthy diet just goes out the window.

    My temptation threshold is lowered if I cheat. Better if I just say no. Anyway, I think I am a recovering sugar addict and need to stay cold-turkey away from it or slide back into that addiction.

  17. Wow I love how this post generated so much college student angst!

    Im a single mum, I work, I attend university full time, and I just broken up with a man I thought I would potentially spend a significant portion (aka the rest of my life) with… guess I should not be sprinting just now.. whew thank goodness…. I was looking for an excuse! LOL

    PS I am secretly please to hear that Carrie has started eating all meats. I used to feel strange that Mark couldn’t convert her! I know that’s wrong on a zillion levels. It is great to hear that she feels better eating all meats. The world feels balanced at last!

  18. Amen to 9 hours of sleep! I can get by on less, but I need about 9 hours to feel really good. Anything less than 7 and I’m pretty worthless the next day.

    With regard to formal exercise, I hate it and always have. I like walking, and I do easy sprints on my exercise bike once or twice a week. By easy, I mean 4 or 5 sets of 20 seconds almost flat-out with 3 minutes recovery. Anything more ambitious than that and my spouse would need to call an ambulance. The rest of my “exercise program” consists of just doing whatever needs to be done–gardening, laundry, cooking, cleaning, etc. Still, I’m in pretty good shape for someone who isn’t very athletic and not exactly a spring chicken.

  19. Ever considered donating feces to members of the Paleo low carb community?

  20. That bit about the sprints just made all my brain cells explode. I had been doing 5-8 sprints on a hill that was just long enough that I started to peeter out when I hit the top. Then whatever time it took me to walk down was my rest, and then I’d do it again. Honestly, though, doing sprints like that just got me really good at giving up when I wasn’t running full-throttle. I don’t like to run farther than a 5K, but doing those kinds of sprints actually don’t benefit my endurance — they have to be in addition to a different run that usually involves time trials. That kind of running, and that kind of biking, is what gets me results.

    I was also shocked to see that Carrie works out so much! That just helps justify how much I prefer to work out. If I did as “little” as Mark did, I don’t stay in shape for things like the random 5K or pick-up game of basketball or racquetball. Talk about one of the most mind-blowing Dear Marks ever!

  21. What if I sprinted for 8 solid minutes, once a week. No rest periods, just 8 minutes of sprinting.

    I would have the body of a Greek God.

  22. I am. 72 yr old female who follows a primal diet and would like to hear more from those in my age group.

    1. I am a 71 yo male who has been on primal for about 4 years. It has worked very well for me but it isn’t going to make me 20 again.

      1. But would you want to be 20 again? Those were some confused years, as I recall. I’m pretty much settling for 35. The GF is 26.

    2. I’m 69 and I have been on low carb and high fat for the last five years. I play tennis three days a week and two or three times a week I either go to the gym and lift weights or do body weight exercises at home, all on a HIIT basis. I plan on starting to do more sprinting. My second biggest Paleo element is a serious consumption of K2 and vitamin D after I learned I had some calcification in my aorta, which every doctor said was “normal.” I did a three month program of very high levels of K2 (7 and 4), both with supplements and cheese. The stuff is like magic. After that my BP dropped to 120/70 and I lost a lot of wrinkles in my face. I highly recommend getting more than enough K2. What I noticed before the K2 was also pain in my upper back sometimes, which has now gone away. That seems to be a symptom of aorta calcification.

  23. Can’t wait to here more from Carrie! It seems like a very long time for the book to be written. I will keep waiting!

  24. “three sets of 5 4-second treadmill sprints with 20 seconds of rest in between each sprint”

    How much rest between sets?

  25. I can recommend trying the 10-20-30 technique. It’s a really great way to sprint, and I’ve experienced great results. First do a warmup for 5-10 minutes, followed by 3 or 4 “blocks” of 30 seconds of jogging (30% of max), 20 seconds of running (60% of max) and 10 seconds of sprinting (90% of max). Now take a break for a couple of minutes, and repeat your 3-4 10-20-30 blocks for 3 or 4 times. A copule of apps exist that are very helpful, and I can really recommend JogRunSprint on the AppStore

    1. @ Heine, sprinting is potentially as tough on the body as any athletic endeavor and consequently one of the most beneficial. Your “tip” is as good as it gets for proper sprinting! Your technique of easing into a sprint(and still at 90 percent) can keep a lot of people injury free. I’m noticing people pushing full speed sprinting which really isn’t necessary unless you’re actually competing.

  26. What about a primal pooping guide ebook? Some tips for crafting the perfect poop.

  27. A lot of people comment on how sprintig isn’t helping with weight loss.
    Could it be possible that what some think is sprinting is in fact just pretty hard run but not an all out sprint?
    I say that because I myself thought I was sprinting. I bragged to my work colleague about how I did 30-60 second sprints. Rested 90 seconds then went again for a total of 15-20 minutes.
    My colleague who plays rugby pointed out that when his team did sprints they’d do 3-4 30 seconds ones with 5 minutes rest and when finished they’d be totally smashed.
    It got me thinking and next time I did sprints I just pushed myself as hard as I could…surprise surprise I could barely last 30 seconds and 90 second rest wasn’t enough. So I realised I wasn’t actually sprinting although I thought I was because it was pretty hard…but not all out sprints! So from 15-20 min of pseudo sprints I’ve gone to 10-15 minuted shorter ones with much longer rest.

    Perhaps that could be the issue here?
    I also think that sprinting on a treadmill might be difficult as one is restricted by the speed of the machine rather than one’s own. One also is focusing on not falling off, checking time, keeps balance etc.
    I do sprint indoors but use machines where I am the driving force only using the resistance as a tool.

  28. I had no idea that sprinting and stress could cause an increase in weight gain. Usually when I’m stressed, I hit up the gym and give it my all. Makes me feel better and I believe stress makes me perform better. Great article though! I will keep this in mind if i decide to start sprinting 🙂

  29. If it wasn’t for sprints, I wouldn’t be doing any cardio. It’s way too boring. I’ve noticed that high intensity running burns more calories overtime, with less work. Rather than pounding my joints for a long period of time and burning limited fat, sprinting has saved me from all of that. I love it and I would recommend it to anyone who is already running. Great write up Mark!

  30. Thanks for the post on sprints. I have a final layer of fat around my belly that I’d like to make disappear, and I imagine that sprints are what I need to do. I have a stationary bike that I used to ride religiously, so cycle sprints are definitely something I could do.

    Being the parent of three young children I empathize with the elevated cortisol issue. With me and my wife I imagine that the lingering weight we have, despite a good diet, is due to the lack of sleep we are enduring.

    Incorporating sprints into our lifestyle is quite a challenge.


  31. When someone states they have their food and exercise “dialed” and proceed to give an example of how NOT to do sprints it makes my wonder if ANYTHING is dialed. First off your not sprinting if you rest 90 seconds and sprint for 30 more seconds and go 8 more times. It’s physiologically impossible because after 30 seconds your lactic acid build up with any anaerobic exercise is in your system for over 4 minutes basically enabling you. I believe what you think is a sprint is more of a spirited jog. If you want to sprint look up “Clyde Hart”. He’s trained track stars like Michael Johnson and Jeramy Wariner and starts you off with the basics.

  32. OK, is it bad that I’m totally jealous of Carrie’s sleep / work-out schedule? It sounds like a dream!!! Some day I will sleep 9 hours a night + work out that much (I love it too!).

    It’s not in the cards right now with a 1 year old, a 4 year old and a FT job. I am able to squeeze in a lunch work out most days now that I’m done pumping (so there’s a start!).

    And I’m sure the 1 year old will be done teething and sleep thru the night soon (hopefully).

    Gosh, I’m still jealous!!!

    1. Ya, I can only dream of sleeping 9 hours! Then I wake up 10 minutes later. It is also a very jealous dream.

  33. Diane,

    I have a theory on why the sprints are less effective when your stressed:

    Looking at the time length of your sprints and, as Mark pointed out the relatively short intervals between these 30 second sprints, you are definitely “flirting” with chronic cardio here – that being the case, as you may be aware as pointed out by Marks primal blueprint book, chronic cardio leads to an increase in cortisone levels, so if you are already stressed out, then doing these “sprints” raises it over the limit, and the body STOPS burning fat, and STARTS burning muscle, which means these sprint sessions are effectively backfiring on you. When you’re in holiday mode, your body can take “the hit” because cortisone levels are lower in general.

    A 30 second sprint is quite long – I do sprints, and I aim for a 15-20 second sprint, at maximum speed – don’t get trapped into thinking that by going a longer time at a slightly slower pace is helpful. If you are truly going your absolute maximum speed for 30 seconds, you should be totally wrecked (this is not a jog, or a fast run, its a SPRINT like your very life depends on it !), and attempting 8 of these with a 90 second rest would kill you. A quick calculation reveals your session lasts at least 16 minutes – you are really well on your way into chronic cardio territory.

    Try this (based on Marks book, and my own tweaks). Do a thorough warm up, all joints, and do a couple of 10 second runs at 70% speed. When REALLY warmed up, Go MAXIMUM, and I mean MAXIMUM speed for 15-20 seconds Max time, no matter what the distance or terrain, and then stop. Wait until you feel you are ready to go “maximum” again for as long as you think you need to rest. The only use of a stop watch in this session is to time how long you have been doing the session in total. Forget about timing each run, and your rest periods between, etc – leave that stuff for the chronic cardio spin classes.

    The whole key to this session is doing however many HIGH QUALITY runs in 10-12 minutes, not how many, or how far. It’s all about max speed. If you do one run, and feel you need to rest 3 minutes before the next, then do it. Just make sure you approach each run at your Max speed, once your speed drops back, it’s time to stop that run (at this point, the Lion just caught you). There is of course a fine line between doing the runs, and being “lazy” on yourself, only you can gauge when your rested enough to “go nuts” for your next run.

    Do this for 10-15 minutes max, and then stop the session.

    remeber, in nature, ther are no points given for doing 8 runs of so mnay metres in a certain time interval. Picture yourself in a lion’s den running for your life – you will either run fast, or be eaten.

  34. PS – some sprinting tips:

    – build up slowly, this is a high impact activity and it can take months/years for your joints and tendons to build the strength required. Muscle strength develops much quicker, which can be a problem when your muscle strength exceeds your joint and tendon abilities as they take much longer to catch up)

    – combine with a body weight / iron weight training program (learn to do pistol squats in GOOD FORM – not those cross fit bouncing half pistols, where people delude themslves that they can actually do a pistol squat. A pistol squat is slow, controlled, right to the bottom, pause at the bottom, come up slow, always using total control, and nom momentum).

    – Up the intensity of the sprint not just by how fast you move your legs, but by increasing the force impact and power of each stride (research sprints on the net – there is a host of form tips around sprinting that I wouldnt know where to start)

    – If your running fast enough, you should be pretty much floating on your toes (yet applying great force to the ground on each stride).

    1. Great point about starting slowly! On too many occasions I myself have started too hard on sprinting and pulled something. I was ready to object to you running at maximum speed on your first post but with your added post it makes more sense especially to most laypeople.

      1. Another way to up the intensity massively without the “dangerous speeds” nad not smashing your joints is to run up a nice grass hill – or go extreme level by running a mud or sand hill – your heart will be jumping out of your chest after 20 seconds – I guarantee it.

  35. It’s nice to see that others, as Carrie acknowledged, struggle with the 80/20. I’ve been primal for a few years now and have no problems avoiding the grains, but when it comes to sweets, I just can’t allow myself to indulge. I have a long history of eating way too much of this stuff if I give myself the opening. Even with dark chocolate, it seems to weaken my will power and create strong cravings in my brain for other carbs and sweets. I’ve had great success for long stretches when I just avoid sweets altogether; the cravings disappear.

    1. Same with me regarding the sweets. I think sugar really has addictive properties for some people.

  36. Yeah! Did some sprints barefoot at Newport Beach while on vacation recently. What a blast. Been sprinting for a couple years.. on grass when weather permits, alternatively on a bike at the gym (always wearing my vibrams). So running barefoot on sand was awesome. Dry was difficult but wet was perfect. Very cool to see the imprints my feet left. I usually do 8 reps at 25 seconds in length. Worked very well at high intensity as I was used up and slowing down in the final 1 or 2 seconds. Way too much fun. Wish I had a beach nearby at home!

  37. Thanks for the helpful information on the sprints. I’ll have to incorporate them into my exercise routine. As always, great post!