Research Roundup #22: Pre-exhaustion for Muscle Gain, Food Preferences and Hunger, Electrolytes and Cramping

It’s estimated that there are over 2+ million scientific papers published each year, and this firehose only seems to intensify.

Even if you narrow your focus to fitness research, it would take several lifetimes to unravel the hairball of studies on nutrition, training, supplementation, and related fields.

This is why my team and I spend thousands of hours each year dissecting and describing scientific studies in articles, podcasts, and books and using the results to formulate our 100% all-natural sports supplements and inform our coaching services. 

And while the principles of proper eating and exercising are simple and somewhat immutable, reviewing new research can reinforce or reshape how we eat, train, and live for the better. 

Thus, each week, I’m going to share three scientific studies on diet, exercise, supplementation, mindset, and lifestyle that will help you gain muscle and strength, lose fat, perform and feel better, live longer, and get and stay healthier. 

This week, you’ll learn if pre-exhaustion helps you gain muscle and strength, whether eating foods you like aids weight loss, and if electrolyte supplements prevent cramps. 

Table of Contents

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• You probably shouldn’t pre-exhaust your muscles.
• Eating foods you like may help you feel fuller.
• Electrolyte supplements don’t prevent muscle cramps.

You probably shouldn’t pre-exhaust your muscles.

Source: “Effects of Pre-exhaustion Versus Traditional Resistance Training on Training Volume, Maximal Strength, and Quadriceps Hypertrophy” published on November 19, 2019 in Frontiers in Physiology.

As the name suggests, “pre-exhaustion” involves fatiguing a muscle using an isolation exercise before performing a compound exercise that trains the same muscle group.

The idea is to ensure your larger, stronger muscle groups are fully stimulated by compound exercises and not limited by smaller contributing muscle groups that might fatigue sooner.

The evidence on whether or not this technique works is mixed: many studies show that it’s a dud or even reduces muscle and strength gain, whereas several others have shown it increases muscle activation in the pre-exhausted muscle and may boost muscle and strength gain, too.

To help cut through the confusion, scientists at the Catholic University of Brasília conducted this study to determine the merits or demerits of pre-exhausting your muscles before training. 

The researchers recruited 31 active men between the ages of 18 and 40 and split them into three groups: 

1. A pre-exhaustion training group.
2. A traditional training group.
3. A control group, which didn’t lift weights. 

For the next 9 weeks, the first 2 groups did 2 tough workouts per week, consisting of 3 sets of leg press to failure with 75% of their one-rep max and resting 1 minute between sets. To fatigue their quads, the pre-exhaustion group performed one set of high-rep leg extensions to muscular failure immediately before their first set of leg press. 

After training their legs, both groups performed one set of several upper-body exercises to round out their workout.

The researchers also had the weightlifters retest their one-rep maxes every 2-to-3 weeks and used the result to increase their weights throughout the study.

To the chagrin of gym bros everywhere, the researchers found no significant differences in muscle growth, strength, or body composition between either training group.

That is, the weightlifters doing traditional workouts gained just as much muscle and strength as those who pre-exhausted their muscles.

The main difference between groups was that the traditional training group did significantly more volume (measured as sets x reps x weight lifted) throughout the study than the pre-exhaustion group.

The reason for this is simple: The pre-exhaustion group’s quads were, well, exhausted before they did their leg press sets, which made them weaker. Thus, they weren’t able to use as much weight or do as many reps, which meant the overall quality of their workouts nosedived. 

Since doing more volume over time is one of the most effective ways to gain muscle and strength, the group that was pre-exhausting their quads would almost certainly gain less muscle and strength over time. 

There is another way to interpret these findings, though.

You could also say the pre-exhaustion group got the same results as the traditional training group while doing significantly less volume, which could be seen as a benefit.

The problem with this stance is that we have a wealth of research showing higher volumes are better for gaining muscle and strength and just one short-term study showing that pre-exhaustion is comparable.

There are also several questions that this study leaves unresolved:

• Is pre-exhaustion only beneficial when using isolation exercises and machines, or would it have a similar effect with free-weight compound exercises (like the squat)?
• Would the effect have been more pronounced if the participants hadn’t taken their pre-exhaustion set to failure, or if they’d been allowed more rest between sets? (Other research suggests this is possible.)
• Would the results have been different if they’d used the same exercise for both the pre-exhaustion and working sets? (A separate study suggests they might.)
• Would this work long-term, or would the reduced volume counteract any possible benefits?

. . . and so on.

Until we have answers to questions like these, it’s hard to recommend pre-exhaustion over more traditional, proven training methods, like the programs you’ll find in my fitness books for men and women, Bigger Leaner Stronger and Thinner Leaner Stronger.

(Or if you aren’t sure if Bigger Leaner Stronger and Thinner Leaner Stronger are right for you or if another training program might be a better fit for your circumstances and goals, then take the Legion Strength Training Quiz, and in less than a minute, you’ll know the perfect strength training program for you. Click here to check it out.)

TL;DR: Pre-exhausting your muscles won’t help you gain muscle or strength and may actually impede your gains over time by reducing the quality of your workouts. 

Eating foods you like may help you feel fuller.

Source: “Better-liked foods can produce more satiety” published in March, 2018 in Food Quality and Preference.

One of the keys to successful dieting is consistency. 

And unsurprisingly, one of the best ways to stick with your diet is to eat foods you like.

Does eating your favorite fare have any other benefits, though?

That’s what scientists at the University of Minnesota wanted to know when they asked 47 people to taste 5 strawberry-blueberry yogurts of varying levels of bitterness and sweetness and record which they preferred.

Thirty participants then returned to the lab to drink a breakfast smoothie made with their preferred yogurt flavor. Immediately before drinking it, after a few sips, and at several points over the next few hours, the participants answered questions about their appetite and liking of the smoothie.

Three hours after the breakfast, the researchers gave the participants 15 minutes to eat as much as they wanted from a snack buffet and measured how many calories they ate.

A week later, the participants returned to the lab and repeated the same process, this time forcing down a smoothie made with the yogurt they didn’t like.

The results showed that after a few mouthfuls, the participants thought the tasty smoothie would fill them, but the unpleasant smoothie wouldn’t. They also felt less hungry and ate significantly less after drinking the tasty smoothie than after the unpleasant smoothie. Specifically, they ate 618 calories after drinking the repulsive smoothie and only 541 calories after drinking the tasty one. 

While this may seem like a trivial difference (77 calories), it could significantly speed weight loss over the course of days, weeks, and months of dieting.

Thus, the researchers concluded that if people eat a food they greatly enjoy instead of one they don’t, they’ll experience more pleasure, satisfaction, and satiety.

This underscores an important point: There’s no reason to prohibit any foods while dieting. Provided you hit your daily calorie and macronutrient targets, you can eat whichever foods you like—and doing so may make the process more straightforward, sustainable, and enjoyable, too.

(And if you feel confused about how many calories and how much of each macronutrient you should eat to reach your health and fitness goals, take the Legion Diet Quiz, and in less than a minute, you’ll know exactly what diet is right for you. Click here to check it out.)

TL;DR: Eating foods you like will probably help you feel less hungry and eat less throughout the day than eating foods you don’t like. 

Electrolyte supplements don’t prevent muscle cramps.

Source: “Serum electrolyte concentrations and hydration status are not associated with exercise associated muscle cramping (EAMC) in distance runners” published on July 23, 2004 in British Journal of Sports Medicine.

“Ugh, another charley horse, I must be low on potassium.” 

You’ve probably heard a friend say something like this (or maybe even said it yourself), and the idea that cramps are caused by a lack of potassium, magnesium, sodium, or another electrolyte has become axiomatic among athletes. 

While this idea is comforting (just drink or eat something and the cramps go away!) and profitable (witness Gatorade, Powerade, and the entire electrolyte supplement industry), it’s also completely wrong.

Many studies have shown that the relationship between cramps and electrolyte levels is much flimsier than sports nutrition companies would have you believe, and one of the best examples comes from a study conducted by scientists at the University of Cape Town. 

The mainline explanation for muscle cramps is that even moderate amounts of exercise quickly deplete your body’s stores of electrolytes, which disrupts normal muscle function and causes cramps. The longer and more exhausting your workouts, the more electrolytes you lose in sweat, and the more likely you are to cramp. 

To test this idea, the scientists measured the relationship between electrolyte levels during the Two Oceans Ultramarathon, a 35-mile foot race held every April in Cape Town, South Africa, when temperatures usually nudge 80+℉.

Seventy-five minutes before the race started, the researchers weighed and took blood samples from 72 experienced male runners, 45 of whom had a history of suffering from cramps (the cramp group) and 27 of whom didn’t (the control group).

During the race, 21 runners from the cramp group suffered cramps, while none of the runners in the control group cramped during or after the race.

Within five minutes of finishing the race, the researchers weighed the runners again and took more blood samples. The scientists then instructed the runners to take 60 minutes to drink as much as they wanted before returning to give another blood sample and complete an interview about the severity and duration of their cramps during the race. 

The results showed zero relationship between the runners’ electrolyte levels and their incidence or severity of muscle cramps. People who experienced frequent, severe muscle cramps during the race were no more likely to have low electrolyte levels than those who didn’t cramp.

If low electrolyte levels don’t cause cramps, what does? 

Scientists haven’t found a smoking gun, but one of the strongest current theories is that cramps result from “altered neuromuscular control.” Basically, there’s a disruption in the electrical signals that cause muscles to contract, which makes them contract excessively and randomly.

It’s not clear what causes this pesky phenomenon, but the most plausible theories include racing at a higher intensity than you’ve trained for (pushing yourself much harder than normal), training in conditions you aren’t accustomed to (such as hot, humid weather), or not eating enough carbs before or during exercising (muscle glycogen depletion). Basically, inadequate preparation for the demands of the sport.

While electrolyte supplements do nothing for your performance or recovery, there are many other supplements that do. If you’re interested in finding out which supplements you should take to reach your health and fitness goals, take the Legion Supplement Finder Quiz, and in less than a minute, you’ll know exactly what supplements are right for you. Click here to check it out.)

TL;DR: Muscle cramps aren’t caused by a lack of electrolytes—inadequate training is probably the real culprit.