ICYMI: Featured guest on “The Bodybuilding Summit”

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A while back, I had the pleasure of sitting down for a podcast with Joshua Vogel. This was part of his “Bodybuilding Summit” event, which featured an incredible list of bodybuilding experts ranging from active researchers to world-class competitors.

I’ve been extremely lucky to have the opportunity to merge my personal interest in bodybuilding with my research activities (a couple examples here and here). In this podcast, we discuss all things bodybuilding, drawing upon experiences from both the gym and the laboratory. Check it out here!


Quick Tip: New research supporting effectiveness of drop sets

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If you follow the fitness research closely, you’re already very familiar with Brad Schoenfeld and Jeremy Loenneke. Brad has made tremendous research contributions in recent years, primarily focusing on very applied, practical questions that are common among gym-goers. Dr. Loenneke is an extremely prolific researcher, with focuses on blood flow restriction and responses to resistance training.

In the past few weeks, both researchers have co-authored brand new research papers discussing drop sets. Drop sets generally take the following form, more or less: You start with a weight, and do it to failure (or near failure). Without resting, you drop the load a little bit, allowing you to get some more repetitions in. The exact protocol can vary, but you’d usually drop weights once or twice in a single drop set. This has been a favorite “intensifying technique” among gym-goers (and even the old bodybuilding magazines) for years, so it’s fun to see it pop up in academic research from time to time.

In the paper by Schoenfeld’s group (Fink et al.), they did a 6-week study comparing a single drop set to 3 normal sets. Loenneke’s group (Ozaki et al.) had a similar set-up for their 8-week studying, comparing three groups: 3 normal sets with a heavy load, 3 normal sets with a lighter load, or a single drop set “cluster” progressing from heavy to light as the load was dropped.

For strength outcomes, the results are fairly intuitive. Fink et al. found greater strength gains from the multiple-set protocol; Ozaki et al. found significant strength gains in the heavy group and the drop set group, but not the light load group. At this point, the research seems pretty clear that in order to improve strength, going heavy is key; we can still make strength gains with light loads, but you’ve got to really push the intensity and approach failure to make it happen.

For muscle growth, the research generally tells us a slightly different story. Heavy training can be an important, effective part of a hypertrophy program, but it appears that light loads elicit plenty of growth when taken to failure. In line with this concept, Ozaki et al. found similar muscle growth across all three groups in their drop set study. Fink et al. saw improvements in both groups as well, although the drop set group experienced a little more growth than the group performing traditional sets.

Getting to the Point

These new studies both support the idea that drop sets may be a helpful technique for promoting strength and hypertrophy. In addition, you’ll note that the drop set groups completed their workouts in less time as well, providing the additional benefit of a more time-efficient workout.

I’m still not a huge advocate of single-set workouts, as the body of evidence largely shows some benefit to multi-set protocols. On the flip side, if you complete a true drop set to failure for your first set of an exercise and try to do more, the quality of sets 2, 3, and beyond are going to be garbage.

When I implement drop sets into my own training, I do it selectively and intentionally. For a muscle group that needs some extra attention, I’ll throw in a drop set as my final set of the final exercise, and really push the intensity to achieve failure. If you’ve never done drop sets before, this new evidence suggests it may be worth a shot.

Quick Tip: Pre-meal beverage to reduce overeating

As I sit 3 weeks out from a bodybuilding competition, the topic of overeating has crossed my mind once or twice this week. I’ve always had tremendous interest in the post-competition rebound from weight loss, which prompted me to contribute a review paper and an original study that touch on the subject.

I will eventually write a big, bloated article about post-competition strategies, but that’s for another day. Today’s post is about a quick tip from the research literature that may help, particularly when you anticipate a meal in which you may be tempted to overeat.

The concept is simple: 0-30 minutes before the meal, you “pre-load” with a beverage, such as 500 mL of water or a protein shake, to reduce how much you eat in the subsequent meal. If you’re someone who is diligently tracking your portions, this obviously will have no effect for you; the benefit is seen for people who are eating ad libitum (i.e., freely determining how much they eat on the fly). The pre-load is basically intended to subconsciously reduce the amount of food you consume. But to the point- does it work?

Despite its simplicity, the research actually does indicate a benefit. Pre-loading, even just with water, has been shown to reduce food intake at the following meal, and to support weight loss over 12 weeks (some studies here, here, and here). Similar studies have been done with pre-meal protein shakes, with similar effects reported. There has been some research to suggest that whey protein is more favorable than soy, but other research showing that pea and casein protein were a little more effective than whey.

For numerous reasons, I would generally tend to recommend some kind of complete, animal-based protein such as whey, casein, egg, or a blend of these sources. A separate study compared egg white isolate, whey isolate, micellar casein, and instant egg whites as protein pre-loads, and found them to be equally effective.

Sure, this post could diverge off into discussions about the psychology of overeating, satiety vs. hedonic eating, and the typical debates surrounding untracked “cheat meals.” But those are for a different day.

Today’s post is simply to highlight research on a practical, quick tip that some may find helpful. Sometimes food-heavy social events don’t align with our dieting plans, and overeating is generally a topic of concern following weight loss, whether the weight loss was health-oriented or competitive in nature. As a result, there are a variety of scenarios where a water or protein pre-load may come in handy!

How to accurately measure and track body composition

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I’ve had the opportunity to contribute some articles to Layne Norton’s website, BioLayne.com. His site has always been one of my most frequently recommended resources and I’ve always had a tremendous amount of respect for Layne, so it’s an honor that I don’t take lightly!

In a recent article, I discuss various methods for measuring your own body composition, how to enhance the accuracy of your measurements, and how to interpret the results. Check it out here! If you happen to become a member of his site, you’ll gain access to countless articles from a great group of contributing fitness experts.

On a related note, the ISSN Annual Conference is June 22-24 in Phoenix, AZ. I will be there presenting some brand new, original data on the validity of body composition tracking in the Data Blitz event, along with an abstract/poster on the same topic. If you’re going to be in attendance, please be sure to stop by my poster presentation and say hello!

ICYMI: Guest spot on Iraki Nutrition Podcast discussing caffeine


I recently had the opportunity to sit down with Juma Iraki to discuss caffeine. We had a great time talking about some of my past research, practical applications for fitness enthusiasts, and lingering questions to be answered in the future. Listen to the whole thing here, via YouTube.

Juma does an incredible job with his podcast, which has featured some amazing guests. If you’re looking for a great, evidence-based fitness podcast, add Juma’s podcast to your list!

The Past, Present, and Future of Nitric Oxide Boosters

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Nutritional supplementation is extremely common among bodybuilders and physique athletes. Whether ingested alone or in a multi-ingredient blend, supplements containing nitric oxide (NO) boosters are among the most commonly used supplements. But why bother with NO boosters?

Nitric oxide is a vasodilator, which increases blood flow. Because NO is gaseous and has a very short half-life, people rely on various NO precursors to help promote NO production. Nitric oxide boosters may benefit exercise performance, soreness, and training adaptations by influencing oxygen and substrate delivery, muscle contractile function, metabolite clearance, and transient cellular swelling. Plus, let’s be honest: In the vain world of bodybuilding, a supplement that causes a temporary “pump” that increases muscle circumference and vascularity is bound to be a crowd favorite.


NO Production

There are two pathways of NO production; one is reliant on the nitric oxide synthase (NOS) enzymes, and the other is not. In the NOS-dependent pathway, L-arginine is oxidized to L-citrulline and NO (1). This process not only requires the presence of NOS enzymes, but also a number of other substrates and cofactors, including oxygen.

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In the NOS-independent pathway, nitrate (NO3) is reduced to nitrite (NO2), which is reduced to NO. This pathway does not require the NOS enzymes, nor does it require oxygen— in fact, this pathway is stimulated by hypoxia (low oxygen availability) and the accumulation of hydrogen ions (H+), which are observed during intense exercise (1).

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The Past

The first generation of NO boosters used one or more forms of arginine as the ingredient of choice. This makes sense, considering arginine’s role in the NOS-dependent pathway. However, arginine has two primary shortcomings. First, it doesn’t appear to improve performance in trained subjects, despite some positive findings in untrained subjects (2). Second, oral arginine supplementation is a poor method of increasing plasma levels of arginine. This is because much of the arginine ingested is metabolized in the gut and liver before it ever has a chance to reach systemic circulation (3). Together, these factors suggest that arginine is not the ideal nitric oxide booster for your pre-workout cocktail. A number of formulations have moved away from an emphasis on arginine, with increased interest in other potential NO boosters.


The Present

I call this section “the present” because ingredients in this section are currently found in many NO supplement blends, and performance-oriented human research on them is at least starting to surface. Compared to arginine, citrulline supplementation presents a better method of increasing plasma arginine levels, which may therefore increase NO production. The most popular form of citrulline, citrulline malate, may also affect exercise performance by influencing ammonia clearance and ATP production (4). Despite citrulline’s excellent reputation, there’s a surprisingly scarce amount of human performance research available. Citrulline malate improves muscular endurance for both upper-body (4) and lower-body (5) resistance exercise, and improves recovery from resistance training (4). What we don’t know, at the moment, is exactly which mechanism(s) deserve the credit. If viewing citrulline specifically as a “nitric oxide booster,” more research is needed to demonstrate that citrulline supplementation increases blood flow during exercise via an NO-mediated mechanism, and that this is actually dictating some of the performance and recovery benefits that have been observed.

Dietary nitrate is another NO booster that falls into the “present” category. The most common nitrate supplements are beetroot-based, but there are others on the market, such as pomegranate extract. Dietary nitrate does improve exercise performance (2, 6, 7), but previous literature has mostly looked at low-intensity, aerobic forms of exercise. In 2014, our lab published a paper demonstrating that pomegranate extract increased blood flow and blood vessel diameter in humans, while improving moderate-intensity running performance (7). We, and other researchers, have since found evidence to suggest that nitrate also helps out with sprint performance (8, 9), and a recent study showed an improvement in resistance exercise performance from beetroot supplementation (10). By targeting a pathway that is stimulated during hypoxic, acidic conditions, dietary nitrate could potentially be an ideal NO-booster for physique athletes doing high-intensity exercise, but this research is only beginning to emerge.


The Future

Future research will certainly tell us more about if (and how) citrulline and dietary nitrate may improve resistance training outcomes. But future research may also inform us of a few “other” ingredients that have snuck their way into some formulations. While these ingredients have already surfaced in a number of products, sufficient human performance research on them is not yet available. Agmatine, commonly seen in the form of agmatine sulfate, is one such ingredient. While agmatine may influence the NOS-dependent pathway of NO production, agmatine itself is not directly converted to NO (11). Agmatine is widely regarded as a vasodilator, but there is conflicting evidence regarding its effects on NO production (11-12), and the only human research on agmatine was evaluating effects on pain and depression symptoms (12, 13). Another one of these “other” ingredients is L-norvaline, which inhibits the arginase enzyme (14). By inhibiting arginase, it may help to preserve serum levels of arginine, thereby supporting NO production. Similarly to agmatine, there is no research directly investigating the effects of norvaline on human exercise performance. Agmatine and norvaline could feasibly make for effective NO-boosters, but we currently lack relevant research to verify this speculation


So, what should a pump-seeking lifter look for in an NO booster?

The future of NO boosters remains to be determined. We still need to determine what (if any) roles agmatine and norvaline can play in these formulations, and what mechanisms are really calling the shots for citrulline malate’s effects. But for now, I’d generally hope that your NO supplement of choice isn’t putting all of its eggs in the arginine basket. Similarly, I’d be a bit cautious about formulations that are entirely focused on agmatine or norvaline, simply due to the lack of human performance research on them. For a consumer interested in boosting NO production, blood flow, and performance, the safest bet would be to seek out a nitrate- or citrulline malate-based product that is effectively dosed. If those criteria are met, you’re likely to experience some of the performance and recovery benefits that have been documented in previous research. And you’ll probably enjoy the transient pump that comes with them.




  1. Bailey SJ, Vanhatalo A, Winyard PG, Jones AM. The nitrate-nitrite-nitric oxide pathway: Its role in human exercise physiology. European Journal of Sport Science. 2011 2012/07/01;12(4):309-20.
  2. Bescos R, Sureda A, Tur JA, Pons A. The effect of nitric-oxide-related supplements on human performance. Sports medicine. 2012 Feb 1;42(2):99-117. Epub 2012/01/21.
  3. Schwedhelm E, Maas R, Freese R, Jung D, Lukacs Z, Jambrecina A, et al. Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine: impact on nitric oxide metabolism. British journal of clinical pharmacology. 2008 Jan;65(1):51-9.
  4. Perez-Guisado J, Jakeman PM. Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. Journal of strength and conditioning research / National Strength & Conditioning Association. 2010 May;24(5):1215-22.
  5. Wax B, Kavazis AN, Weldon K, Sperlak J. Effects of supplemental citrulline malate ingestion during repeated bouts of lower-body exercise in advanced weightlifters. Journal of strength and conditioning research / National Strength & Conditioning Association. 2015 Mar;29(3):786-92.
  6. Lansley KE, Winyard PG, Bailey SJ, Vanhatalo A, Wilkerson DP, Blackwell JR, et al. Acute dietary nitrate supplementation improves cycling time trial performance. Med Sci Sports Exerc. 2011 Jun;43(6):1125-31. Epub 2011/04/08.
  7. Trexler ET, Smith-Ryan AE, Melvin MN, Roelofs EJ, Wingfield HL. Effects of pomegranate extract on blood flow and running time to exhaustion. Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. 2014 Sep;39(9):1038-42.
  8. Roelofs EJ, Smith-Ryan AE, Trexler ET, Hirsch KR, Mock MG. Effects of pomegranate extract on blood flow and vessel diameter after high-intensity exercise in young, healthy adults. Eur J Sport Sci. 2017 Apr;17(3):317-25.
  9. Wylie LJ, Bailey SJ, Kelly J, Blackwell JR, Vanhatalo A, Jones AM. Influence of beetroot juice supplementation on intermittent exercise performance. European journal of applied physiology. 2016 Feb;116(2):415-25.
  10. Mosher S, Sparks SA, Williams E, Bentley DJ, Mc Naughton LR. Ingestion of a nitric oxide enhancing supplement improves resistance exercise performance. Journal of strength and conditioning research / National Strength & Conditioning Association. 2016 Apr 2.
  11. Galea E, Regunathan S, Eliopoulos V, Feinstein DL, Reis DJ. Inhibition of mammalian nitric oxide synthases by agmatine, an endogenous polyamine formed by decarboxylation of arginine. The Biochemical journal. 1996 May 15;316 ( Pt 1):247-9.
  12. Keynan O, Mirovsky Y, Dekel S, Gilad VH, Gilad GM. Safety and Efficacy of Dietary Agmatine Sulfate in Lumbar Disc-associated Radiculopathy. An Open-label, Dose-escalating Study Followed by a Randomized, Double-blind, Placebo-controlled Trial. Pain medicine. 2010 Mar;11(3):356-68.
  13. Shopsin B. The clinical antidepressant effect of exogenous agmatine is not reversed by parachlorophenylalanine: a pilot study. Acta neuropsychiatrica. 2013 Apr;25(2):113-8.
  14. Chang CI, Liao JC, Kuo L. Arginase modulates nitric oxide production in activated macrophages. Am J Physiol. 1998 Jan;274(1 Pt 2):H342-8.


Recent Research: DEXA confounded by carbohydrate and creatine loading


Some fairly recent research highlights a point that has created some buzz lately: Things that influence body water storage, such as carbohydrate or creatine loading, will influence the results of a DEXA (dual-energy x-ray absorptiometry) scan. Simply put, manipulating these factors will influence DEXA estimates for body fat and lean mass.

When we measure body composition, we have to choose a certain “model.” A 2-compartment model breaks the body into two compartments: fat mass, and lean mass. Depending on the equipment available, we can expand out to more elaborate models that further account for bone/mineral content, body water, and other compartments.

Many of the common methods we use for measuring body fat, whether in research studies or with clients, use 2- or 3-compartment models that don’t include body water. The result: Body water will inevitably be counted as “something else” in these models.

As shown in this study, dietary loading with carbs or creatine will increase the water content of your muscles. This will cause the DEXA results to reflect greater lean mass, and less relative fat mass. You could also look at the inverse situation- if you did a DEXA when you were on creatine and full of glycogen, then stopped taking creatine and repeated the scan after 8 weeks of a low-carb diet, the scan may show huge losses of lean mass, even if you didn’t lose much actual muscle tissue.

I really want to highlight that the findings of this study, and others like it, do not exclusively pertain to DEXA! In essence, these findings would pertain to just about any body fat estimate that doesn’t directly account for total body water, including BodPod, skinfolds, and underwater weighing, among others.

Our lab uses a variety of methods for body composition assessment, mostly depending on what is feasible for each individual study. We have used a 4-compartment model that directly accounts for total body water, but we have also done studies where time or equipment limitations made it impossible to do so. When you can’t account for body water, it’s even more important to standardize pre-visit instructions to minimize some of these potential confounding factors, and to make sure that the study intervention won’t disproportionately affect these factors in certain groups within the sample.

So what does that mean for you?

1) If you’re reading a study or an abstract measuring body composition, did their estimation model account for body water? If not, consider how that might influence the study’s results.

2) If you’re measuring or tracking your own body composition, be consistent! Whenever possible, do your scans in a fasted state at a similar time of day, try to avoid any unusual glycogen depletion or loading, and try to keep things like creatine supplementation and hydration status constant.

If you want to read more about body composition measurement, here is a tremendous review paper on the subject.