Dear Mark: Following the Money, HIIT Workouts, HIIT and ACL Recovery, Spinach, Collagen Timing

For today’s edition of Dear Mark, I’m answering six questions from readers. First, is funding from a biased source sufficient to negate a study’s results? Second, what are some good high intensity interval training workouts that people might not have considered? Third, what can someone recovering from an ACL tear do for HIIT without triggering knee pain flareups? Fourth, how do I like to eat spinach? And finally, how and when do I like to take collagen?

Let’s go:

On the nuts vs. carbs study, I want to say ‘follow the money’ since it was funded by the International Tree Nut Council Nutrition Research and Education Foundation. Then again, it was also funded by the Peanut Institute, so I don’t know what to think…

“Following the money” isn’t enough to come to any conclusions about the worth of a study. We can’t declare a study tainted based on bias alone, especially because we can’t avoid bias. Every person reading studies and deciding which one to write about is biased. Every organization meting out funding has biases. Every entity in the known universe has an agenda. It’s not “bad” (or good). It simply is.

If the cow consortium funds the “red meat is actually good for you” study, red meat is still good for you. The bias doesn’t negate the facts. Big Soy funds the “don’t worry about the quarter cup of soybean oil in your restaurant food” study, but it’s only a mark against the paper if the science was shoddy and the conflict of interest exerted influence (which it probably was and did).

But I totally understand where you’re coming from. There’s an entrenched bias against most of the health advice we support. The powers that be have spent decades telling us to avoid the sun, restrict meat (especially red meat), go vegetarian, eat low-fat, get “more complex carbohydrates,” use seed oils, do cardio over weights, eat less salt, and blindly drink more water. They’re not just going to go away—and they aren’t.

So whenever I see a study’s been funded by an obviously biased source, I can’t help but wonder and look more deeply at the paper with a skeptical eye. It sounds like you do the same. That’s great. It’s the kind of healthy skepticism we should all have and employ in our search for good information.

We just can’t stop there.

If the results  of a study are unfavorable to the funders, it’s a strong indication that the funding didn’t interfere with the science.

If the results are favorable to the funders, our hackles rise. We examine the study methods, design, and results to see if bias affected the results. Many times it doesn’t. Sometimes it does.

Can you point us in the direction of a good HIIT workout and what it should look like?

Here are a couple ideas:

Hill sprints. Find a hill and run up, then walk down. Walking down serves as active recovery. Steeper hills, shorter sprints with more rest. Hills with a gradual incline, longer sprints. All permutations work. Though extremely difficult, hill sprints are good options for many people with lower body injuries that flare up on flat ground sprints; running up a hill is gentler on your joints.

Barbell complexes. Pick 3-4 barbell movements. Clean and press for 5 reps. Romanian deadlift for 5 reps. Clean to shoulders, then front squat for 5 reps. Finish with 5 bent over rows. Do that without stopping or dropping the weight. That’s a complex. Drop the bar and rest a minute or two, then do another complex. Repeat. This works with any barbell movement, and you can even do kettlebell or bodyweight complexes. Adjust weight and reps accordingly. These complexes should be hard (but over quickly).

I tore my ACL 6 months ago. Although I am walking 5-7 miles a day and doing heavy lifting for my upper body. I am only able to do ball squats carefully at this point. Any HIIT ideas for me at this point? The bike causes pain on the front of my knee still.

Check with your doctor, but deadlifts are probably safe during knee rehab. Do them right and there’s very little knee flexion (it sounds like flexion hurts the knee); it’s all hip extension.

Deadlifts can become “cardio” if you drop the weight and increase the reps. Just maintain impeccable form. Don’t sacrifice technique (and back health) for a couple extra reps.

If you can deadlift safely for high reps without pain, the next thing to try is the kettlebell swing. Swinging a kettlebell is very similar to deadlifting a barbell—it’s all hip extension—and lends itself well to high-rep, HIIT-style workouts.

I’m one of few people I know who enjoys eating basically any type of offal (no problems with raw), but can’t handle spinach by itself. Any advice? Also, ever tried meditatin’?

And here’s where I’ll get thrown out of my own movement because of one of the ingredients.

Sauté spinach (frozen or fresh) in butter for a minute, add a handful of corn kernels (fresh or frozen, but organic or at least non-GMO), add salt, pepper, and dried chipotle pepper powder (as much as you can tolerate), cover, and turn heat to low. After about ten minutes, it’s ready. Finish with grated sharp cheddar or pecorino romano.

I don’t eat this often (never while keto), and it’s certainly not the only way I enjoy spinach. A good raw spinach salad is fantastic, as is basic sautéd spinach without the corn. But I’ve never met anyone who didn’t like the spinach-corn-chipotle recipe, even avowed spinach haters like yourself.

I’m curious about when Mark was supplementing heavily with collagen. Did he do that at breakfast as his only food, lunch in lieu of some other protein, a shake between lunch and dinner? What have other folks done?

I’m wary of too much protein in one sitting.

I would have 2-3 tablespoons of collagen with a little vitamin C half an hour before a workout. That’s been shown to increase collagen synthesis, a necessary step for healing tendons and other tissues.

That’s it for today, folks. Thanks for reading and take care!

Be sure to add your own comments, questions, and input down below.

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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26 thoughts on “Dear Mark: Following the Money, HIIT Workouts, HIIT and ACL Recovery, Spinach, Collagen Timing”

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  1. The issue of bias is, I think, a bit more complicated than your discussion of it. The issue comes up a lot in the legal system for obvious reasons, and people get it wrong all the time. The law distinguishes 2 kinds of bias:

    1. General attitudes and preferences. For example, a judge might politically favor or oppose abortion rights. This, however, is NOT a basis for disqualifying him/her for bias in a case involving abortion. That’s because, as you say in your post, this kind of bias is unavoidable.

    2. It’s the second kind of bias which provides a basis for disqualification. This happens when the bias is *specific* to a person or *particular* to an issue. For example, a judge can’t sit in a case involving a family member. Nor in a case in which s/he has a personal financial interest.

    I think the question to you treated the study as involving bias #2, but your answer only dealt with bias #1.

    Note that the study can still reach a correct result even if bias #2 is involved. We can’t throw it out because of bias, but we can treat it more skeptically and look for other evidence.

    1. Can collagen help with a torn meniscus. I was told these cannot heal.

    2. Those two classes of bias are, while explainable with so many words, completely arbitrary and do not in any way relate to the effect they will have.

      A judge’s strong opposition to abortion rights might easily have more influence on a case than a distant blood-relationship or low-grade shared financial interest. So the kind of bias, lastly, is unimportant.

  2. Thanks for the reminder about barbell complexes Mark, have not done them for a while … how soon we forget!

  3. I think the bigger problem with bias is that it’s often close to impossible (or totally) impossible to tell if or how a study was influenced by bias. Unpublished or missing adjustment calculations are one common and glaring example of this. Bias in drop-out reporting or participant selection that is undetectable in the study results is another (i.e. doing a weight-loss study where some people are naturally lean and others in another group are not.) Unpublished raw data that could contain extreme outliers is another. It’s kind of like a magic don’t need to know the trick to be highly confident there is a trick involved. Drug companies are apparently known to favor researchers who produce “the correct” results so in such cases it seems reasonable to assume that even if a study looks reasonable it needs to be confirmed by unbiased research and real-world results.

    A good place to start to correct this problem could be to require all published research to be repeatable (i.e. be actual science) which should take care of the adjustment calculation issue since it would have to be published.

  4. Oh, ain’t no spinach hater! Just haven’t found many contexts in which I can enjoy it as a foreground contributor to the flavor of a meal. I seem to drown it into the background, rarely making it a centerpiece of my meals. The silent hero who I need but certainly don’t deserve.

    I’ll think yr suggestion through.

    1. Totally agree. It’s like all other leafy greens for me, I have to mix it in a stir-fry and/or burn the hell out of it. I genuinely enjoy it when it’s very browned/partially burnt, but not so sure about how the nutrition holds up through all that cooking…

  5. Re” bias in studies, absolutely we must be skeptical when a study has been funded by a party with interest. As you say, Mark, this doesn’t necessarily negate the findings, but it’s important to read carefully with a wary eye.

    Another thing people often don’t realize–there are thousands of fake scientific journals and “predatory” publishers out there (see, for example, And there are countless journals that do little or no peer reviewing or editing & fact-checking. I work in medical publishing, and I’ve seen some terrible stuff get to print. Caution and skepticism are essential these days.

  6. Peter, I can attest that a torn meniscus can indeed heal. Had pretty good one from Cross Fit 3 years ago (too old for that anyway). Sports Doc and Surgeon suggested surgery and would always have the tear.

    I passed on the surgey, quit Cross Fit, discovered Primal Blueprint, including lots of Mark’s vanilla collagen and bone broth. Dropped 25 pounds.

    Joined new gym (Cross Fit Light….) Lots of single leg mobility work and over course of a year, dropped brace, started sprinting and doing lunges and box jumps again with no pain.

    Collagen was a small part for sure, but my point is I went from pretty serious interior meniscus tear to a knee working at about 95% without surgey. I am 58 now.

    For me it was combination of eating right and finding the right gym to slowly build back the tissue and joint strength.

    Hang in there and good luck!

  7. Spinach is great sautéed in avocado oil with a little bit of garlic. I also love it for green drinks…tomorrow morning I am having spinach, celery and lemon. I threw a handful of spinach, two chopped stalks of celery and a whole peeled lemon in my vitamix and covered half way with water. Tomorrow am I’ll blend and drink. That collagen synthesis that Mark talked about with the collagen peptides and vitamin C isn’t just great for tendons, it’s amazing for firming up your skin!

  8. Barbell complexes are intense. I remember when I first did them, definately a great cardio workout. I also like taking different high intensity things and combining them.

    Like start with a number say 5, do 5 kettlebell swings, then 5 burpees. Rest briefly then 4,3,2,1.

    Or the old shuttle run but with kettlebell swings at one end, burpees at the other, and for extra craziness don’t run to the other end but bear crawl. This had me laying on the floor puffing hard when I did it and probably had people at the gym thinking I was mental.

    Start small on these as they wear you out more than you expect.

  9. I love to add handfuls of spinach to anything I’m blending in the Vitamix: pasta sauce, veggie dips, smoothies, creamy soups. No one can ever detect the spinach- even kids who swear they won’t eat spinach.

    1. After a while you can test it by adding brussel sprouts and broccoli to everything.

      “Mum why is there broccoli in my chocolate” 😀

  10. I just love your QA session. The every QA session provides a lot of beneficial information about health and fitness. In this session get crucial tips some good high-intensity interval training workouts, how to recover from ACL tear do for HIIT without triggering knee pain flare-ups, about eating spinach, and the right time to take collagen. This information is quite helpful for many.

  11. On spinach my advice is, it pairs very well with garlic. And chop it up.

    As for bias, there’s a lot of money in science right now. Megacorps are farming out their studies (keeping their name on it), and then if the results aren’t what they want, they simply don’t publish. So if you see something negative that looks good because it’s neg against the megacorp that funded it, ask yourself what would be worse. Maybe it’s misdirection. If you think I’m being paranoid, you haven’t read enough science to notice that effect.

    Some good books on bias in science are of course the well known Death by Food Pyramid, and Doctoring Data (Malcolm Kendrick MD). If you want to see a knock down drag out, full of retractions fight in science you need to look at ME/CFS for the dirty underbelly. Start with Plague by Judy Mikovits PhD and then look at the funding for Ron Davis PhD whose son is literally dying of that disease and is fully incapacitated by it. NIH denied him a grant just in the last year. It’s a petty spat in my opinion, but you can form your own. Arguments in science are helpful to megacorps because as long as the answers are hidden, they can rake in the money with “treatments” instead of cures.

    If you think that’s paranoid, then you need to google a Goldman Sachs report called “The Genome Revolution” where one of the analysts Salveen Richter says basically that and argues against science being applied to discover cures for illnesses. Why? Because it’s bad business to cure patients. I kid you not.

  12. Here’s my question, Mark, you can answer it another time if you want.. or people can reply and tell me what they think.. Why do Paleos and Primals go all out to find grass fed and pastured meat, and then turn around and snub the organic label? I see it on blogs more and more, cutesy phrases like “dirty dozen” and “clean fifteen” that make it out that organic is just about chemicals and not about the soil maintenance. Hey people, vegetables have the nutrients they can get from the soil, that’s all, nothing else. If you snub organic, then your food is lower in nutrients. Why would a someone do that if they’re also seeking grass fed / pastured meat? Seems so illogical to me.

    1. Per The Rational Optimist, the world doesn’t have enough arable land to support all organic farming. Enter the Haber-Bosch, whereby we can fix nitrogen (think fertilizer) and dramatically increase the amount of food produced. Organic, however, also refers to the spraying of pesticides (or lack thereof). It’s a above and below ground definition.

      I see your point, but it’s a function of pragmatism

  13. For spinach, try sigeumchi/shigumchi namul, a Korean side dish. I make a batch with ~200g at a time and keep it in the fridge.

    Full disclosure: I loooooove spinach. 🙂

  14. I like the suggestion of hills as an enhancement for exercise. I personally detest hills and believe the world should be like northwest Indiana. But I understand that there are those among us who appreciate the lack of a true horizon and are drawn to mountains and such.

    Using a hill in exercise might actually justify its existence for me. 😀

  15. Thank you Framistat and Spider with your helpful link and advice in regards to my meniscus tear.

  16. Okay, but it’s a free country (for now) and you are an adult and can eat whatever you desire..even non-Primal ingredients (gasp)…but like, do you not feel that a handful of roasted and chunked macs or Brazillian nuts would work as nicely in that spinach concoction?

  17. Interesting on the timing of collagen. I have been wondering myself. I take it pre-run instead of post run and wondered which was better.

    I’ve experimented a bit on timing but haven’t seen any real difference.

    So the consensus is pre?