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 five 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 the real reason pre-workout meals are important, whether creatine can make you smarter, how browsing social media during your workouts makes you weaker, and more.
Table of Contents
Source: “Compatibility of Concurrent Aerobic and Strength Training for Skeletal Muscle Size and Function: An Updated Systematic Review and Meta-Analysis” published on November 10, 2021 in Sports Medicine.
The idea that cardio will kill your gains is one of the most stubborn fitness pieties, and you’ll still find overweening “influencers” who claim that running burns muscle and other trite silliness.
Although this makes for juicy contrarian clickbait, scientists have known this is nonsense for decades, and this study conducted by researchers at the German Sport University adds to the growing body of evidence proving that cardio isn’t that bad for your gains after all.
In their systematic review and meta-analysis, the researchers parsed the results of 43 studies including a total of 1,090 participants and found that “concurrent training” (a training program that includes weightlifting and endurance training) didn’t lead to significantly smaller strength gains or less hypertrophy than weightlifting alone.
Further subanalyses showed that strength gain and hypertrophy were unaffected by the kind of endurance training performed, how often it was done, the proximity of the cardio and strength training workouts, or the age and experience level of the athlete. In other words, the researchers found that the “interference effect” simply wasn’t worth worrying about for most people.
At this point you might be wondering, if this is true, then where are all of the jacked marathon runners?
An excellent question with a simple answer: the vast majority of studies that have looked at the interference effect and concurrent training as a whole have involved fairly low volume cardio programs—a few hours per week at most—which is less than 1/10th of what many competitive endurance athletes do.
The takeaway from this study, then, isn’t that you can do as much cardio as you want without paying the piper, but that doing two or three hours of moderate intensity endurance training isn’t going to hurt your gains. (Which is also what I recommend in my programs for men and women).
The researchers also found that cardio did interfere with explosive strength (power), so you should be wary of how much cardio you do if you participate in sports like Olympic weightlifting, gymnastics, and so on. (Despite the name, “powerlifting” doesn’t require much explosive strength, so it wouldn’t fall into this category.)
The Takeaway: Doing a few hours of endurance training per week doesn’t interfere with your ability to build muscle and gain strength, though it does hamper explosive power.
Source: “Effect of a hypocaloric diet, increased protein intake and resistance training on lean mass gains and fat mass loss in overweight police officers” on May 26, 2000 in Annals Of Nutrition And Metabolism.
You can group most recreational weightlifters’ goals into two broad categories: Building muscle and losing fat. Unfortunately, these two goals have “irreconcilable differences,” because gaining muscle requires a calorie surplus and losing fat a calorie deficit. Thus, achieving both simultaneously isn’t possible for most people.
There are two exceptions to this rule, though: people on steroids, and people who are new to weightlifting.
The most impressive example of “body recomposition” in greenhorn weightlifters comes from a study conducted by scientists at Brigham and Women’s Hospital on 38 overweight, sedentary, middle-aged police officers.
The average age of the participants was 34 years old, none of them had any previous weightlifting experience, and they were all around 27% body fat on average.
After 12 weeks of maintaining a 20% calorie deficit and eating 0.7 grams of protein per pound of body weight per day, the participants lost 9-to-15 pounds of body fat and gained 4-to-9 pounds of muscle on average.
Here’s a chart from the study showing the body recomposition effect experienced by the participants:
It’s worth underlining that this staggering transformation was achieved using a completely run-of-the-mill diet and training plan: The participants lifted weights, reduced their calorie intake, and ate a sufficient (if not slightly low) amount of protein, and achieved near perfect “recomp.” No fitness frippery like intermittent fasting, HIIT, unscientific fat loss supplements, or low-carb dieting required.
These results are impressive, but not uncommon for beginners. And if you want proof, just check out some of the success stories from men and women who followed my Bigger Leaner Stronger and Thinner Leaner Stronger programs, which involve a similar, although I’d argue, better formulated training and diet plan to what these folks did.
The Takeaway: During your first few months of training you can rapidly build muscle and lose fat simultaneously, provided you lift weights, maintain a calorie deficit, and eat sufficient protein.
Source: “Viscous Placebo and Carbohydrate Breakfasts Similarly Decrease Appetite and Increase Resistance Exercise Performance Compared with a Control Breakfast in Trained Males” published on March 16, 2020 in British Journal of Nutrition.
Many people think they need to eat a small meal before training to perform at their best (and many supplement companies give this idea currency and claim their products are ideal for this pre-workout meal).
And while eating before training can improve your performance, research conducted by scientists at Loughborough University shows this boost may be more psychological than related to energy availability.
In this study, the researchers had 22 resistance-trained men who normally ate breakfast report to the lab for 3 separate training sessions consisting of 4 sets of the squat and bench press to failure with 90% of their 10 rep-max.
Two hours before each training session, the participants consumed one of three breakfasts: Water; a viscous carbohydrate-based breakfast (a gel, basically, which I imagine looks something like this); or a viscous, very low-calorie placebo breakfast. Both gel breakfasts tasted and looked the same, and the researchers told the participants that they both contained calories.
The results showed that the participants performed ~15% more total reps on the squat and ~4% more total reps on the bench press after eating the gel than after drinking only water. Although the high-calorie gel raised insulin and glucose more than the low-calorie one, the weightlifters felt equally full and performed just as many reps after both.
In other words, drinking the breakfast slop didn’t improve the weightlifters performance because it provided more energy, but because it helped them feel more satiated.
Given how few calories you burn when weightlifting, it’s not all that surprising that pre-workout meals aren’t as important as many people claim. Instead of “fueling” your workout, their main function is to help you feel full and prevent hunger from undermining your performance.
That said, if you’re doing a particularly long, intense workout that burns a lot of calories, like a moderate-intensity 90-minute bike ride, research shows that you’ll probably perform better if you eat a small meal beforehand. In scenarios like these, consuming ~30-to-40 grams of carbs (and some protein and fat if you like) ~30 minutes before you train will get the job done. (And even then, if you ate a large meal several hours before this, this pre-workout meal becomes much less important.)
This may seem humdrum, but it’s worth remembering the next time you hear a sports nutrition company claim you should “fuel up” before your next workout . . . and then conveniently recommend their “optimum-release muscle fueling matrix with added BCAAs and electrolytes” as the perfect pre-workout meal.
Not only are these products a waste of money for most people, they’re arguably worse than a snack like an apple with a cup of Greek yogurt, which costs less, is more nutritious, and is going to do a better job of keeping you satiated.
The Takeaway: Pre-workout meals probably don’t improve your performance by giving you more energy, but instead by preventing you from feeling hungry while you train.
How many calories should you eat? What about "macros?" What foods should you eat? Take our 60-second quiz to get science-based answers to these questions and more.
Find the Best Diet for You in Just 60 Seconds
How many calories should you eat? What about "macros?" What foods should you eat? Take our 60-second quiz to get science-based answers to these questions and more.Take the Quiz
Source: “Effects of creatine supplementation on cognitive function of healthy individuals: A systematic review of randomized controlled trials” published on July 15, 2018 in Experimental Gerontology.
In their meta-analysis of 6 studies containing a total of 281 participants, the researchers found that supplementing with creatine likely improves short-term memory and intelligence (reasoning and mathematical processing).
For example, in one of the studies they reviewed, elderly participants who supplemented with 20 grams of creatine monohydrate per day for a week performed better at tasks involving remembering sequences of numbers and ordering wooden blocks than participants who took a placebo.
The review also found some evidence creatine improves long-term memory, spatial memory, memory scanning, attention, “response inhibition,” word fluency, and mental fatigue, but the results were too inconsistent to be conclusive. Two other recent reviews found that creatine may also improve brain health in people with mild traumatic brain injuries, concussion, and depression.
While taking creatine probably won’t help you unpuzzle the Collatz conjecture, it’s nice to know that it may benefit our brains as well as our biceps. And if you want a 100% natural source of creatine that also includes two other ingredients that will help boost muscle growth and improve recovery, try Recharge.
(Or if you aren’t sure that Recharge is the right fit for your budget, circumstances, and goals, then take the Legion Supplement Finder Quiz! In less than a minute, it’ll tell you exactly what supplements are right for you. Click here to check it out.)
The Takeaway: Creatine boosts short-term memory and intelligence and may also improve several other aspects of cognitive function, including long-term memory, spatial memory, memory scanning, attention, “response inhibition,” word fluency, and mental fatigue.
Source: “Mental Fatigue From Smartphone Use Reduces Volume-Load in Resistance Training: A Randomized, Single-Blinded Cross-Over Study” published on May 17, 2021 in Perceptual and Motor Skills.
Look around most gyms, and you’ll see that nine out of ten people are fixated on their phones and probably scrolling through their social media feeds between sets.
This might seem like a harmless diversion to make your rest periods less boring, but this study found that it may hurt your gains.
Researchers at the Federal University of Paraíba had 16 experienced male and female weightlifters do a workout that involved 3 sets of squats to failure, then look at social media or watch a documentary for 30 minutes before doing a second workout of 3 sets of squats to failure.
At the end of the study, the results showed that the weightlifters who watched the documentary completed about 15% fewer reps in their second workout, whereas the group pottering on social media performed 29% fewer reps. The researchers also found that the social media group experienced much higher “mental fatigue,” too (~60% vs. ~15%).
These results aren’t an anomaly. Many studies have shown that using technology such as smartphones to perform “mentally taxing” tasks like scrolling through social media has a detrimental effect on athletic performance.
That’s in addition to making you feel more anxious, lonely, depressed, suspicious, distracted, jealous, stressed, unworthy, unsatisfied, ugly, misinformed, vulnerable, untrusting, aggressive, and narcissistic. But hey, at least you know what Dwayne Johnson ate on his cheat day.
What’s the best way to prevent social media from putting you off your stride?
- Don’t use social media for at least 30 minutes before or during your workouts (and it’s probably best if you ditch the mindless web surfing and video watching, too). If you find this difficult, download a program that blocks social media (and other websites) for a pre-set period of time, like Freedom.
- Instead of browsing social media between sets, visualize your next set, focus on weightlifting cues to improve your technique, and listen to music.
The Takeaway: Using social media before you train impairs your athletics performance. Avoid using it while you work out and for at least 30 minutes beforehand.
+ Scientific References
- Demling, R. H., & DeSanti, L. (2000). Effect of a hypocaloric diet, increased protein intake and resistance training on lean mass gains and fat mass loss in overweight police officers. Annals of Nutrition & Metabolism, 44(1), 21–29. https://doi.org/10.1159/000012817
- Tnønessen, E., Sylta, Ø., Haugen, T. A., Hem, E., Svendsen, I. S., & Seiler, S. (2014). The Road to Gold: Training and Peaking Characteristics in the Year Prior to a Gold Medal Endurance Performance. PLOS ONE, 9(7), e101796. https://doi.org/10.1371/JOURNAL.PONE.0101796
- Bellinger, P., Arnold, B., & Minahan, C. (2019). Quantifying the Training-Intensity Distribution in Middle-Distance Runners: The Influence of Different Methods of Training-Intensity Quantification. International Journal of Sports Physiology and Performance, 15(3), 319–323. https://doi.org/10.1123/IJSPP.2019-0298
- Hickson, R. C. (1980). Interference of strength development by simultaneously training for strength and endurance. European Journal of Applied Physiology and Occupational Physiology, 45(2–3), 255–263. https://doi.org/10.1007/BF00421333
- Schumann, M., Feuerbacher, J. F., Sünkeler, M., Freitag, N., Rønnestad, B. R., Doma, K., & Lundberg, T. R. (2022). Compatibility of Concurrent Aerobic and Strength Training for Skeletal Muscle Size and Function: An Updated Systematic Review and Meta-Analysis. Sports Medicine (Auckland, N.Z.), 52(3), 601–612. https://doi.org/10.1007/S40279-021-01587-7
- Naharudin, M. N., Adams, J., Richardson, H., Thomson, T., Oxinou, C., Marshall, C., Clayton, D. J., Mears, S. A., Yusof, A., Hulston, C. J., & James, L. J. (2020). Viscous placebo and carbohydrate breakfasts similarly decrease appetite and increase resistance exercise performance compared with a control breakfast in trained males. The British Journal of Nutrition, 124(2), 232–240. https://doi.org/10.1017/S0007114520001002
- Hargreaves, M., Hawley, J. A., & Jeukendrup, A. (2004). Pre-exercise carbohydrate and fat ingestion: effects on metabolism and performance. Journal of Sports Sciences, 22(1), 31–38. https://doi.org/10.1080/0264041031000140536
- Mata, F., Valenzuela, P. L., Gimenez, J., Tur, C., Ferreria, D., Domínguez, R., Sanchez-Oliver, A. J., & Sanz, J. M. M. (2019). Carbohydrate Availability and Physical Performance: Physiological Overview and Practical Recommendations. Nutrients, 11(5). https://doi.org/10.3390/NU11051084
- Conley, M. S., & Stone, M. H. (1996). Carbohydrate Ingestion/Supplementation for Resistance Exercise and Training. Sports Medicine, 21(1), 7–17. https://doi.org/10.2165/00007256-199621010-00002
- Avgerinos, K. I., Spyrou, N., Bougioukas, K. I., & Kapogiannis, D. (2018). Effects of creatine supplementation on cognitive function of healthy individuals: A systematic review of randomized controlled trials. Experimental Gerontology, 108, 166–173. https://doi.org/10.1016/J.EXGER.2018.04.013
- McMorris, T., Mielcarz, G., Harris, R. C., Swain, J. P., & Howard, A. (2007). Creatine supplementation and cognitive performance in elderly individuals. Neuropsychology, Development, and Cognition. Section B, Aging, Neuropsychology and Cognition, 14(5), 517–528. https://doi.org/10.1080/13825580600788100
- Forbes, S. C., Cordingley, D. M., Cornish, S. M., Gualano, B., Roschel, H., Ostojic, S. M., Rawson, E. S., Roy, B. D., Prokopidis, K., Giannos, P., & Candow, D. G. (2022). Effects of Creatine Supplementation on Brain Function and Health. Nutrients 2022, Vol. 14, Page 921, 14(5), 921. https://doi.org/10.3390/NU14050921
- Roschel, H., Gualano, B., Ostojic, S. M., & Rawson, E. S. (2021). Creatine Supplementation and Brain Health. Nutrients, 13(2), 1–10. https://doi.org/10.3390/NU13020586
- Gantois, P., Lima-Júnior, D. de, Fortes, L. de S., Batista, G. R., Nakamura, F. Y., & Fonseca, F. de S. (2021). Mental Fatigue From Smartphone Use Reduces Volume-Load in Resistance Training: A Randomized, Single-Blinded Cross-Over Study. Perceptual and Motor Skills, 128(4), 1640–1659. https://doi.org/10.1177/00315125211016233
- Queiros, V. S. de, Dantas, M., Fortes, L. de S., Silva, L. F. da, Silva, G. M. da, Dantas, P. M. S., & Cabral, B. G. de A. T. (2021). Mental Fatigue Reduces Training Volume in Resistance Exercise: A Cross-Over and Randomized Study. Perceptual and Motor Skills, 128(1), 409–423. https://doi.org/10.1177/0031512520958935
- Gantois, P., Caputo Ferreira, M. E., Lima-Junior, D. de, Nakamura, F. Y., Batista, G. R., Fonseca, F. S., & Fortes, L. de S. (2020). Effects of mental fatigue on passing decision-making performance in professional soccer athletes. European Journal of Sport Science, 20(4), 534–543. https://doi.org/10.1080/17461391.2019.1656781
- Fortes, L. S., Lima-Júnior, D. de, Gantois, P., Nasicmento-Júnior, J. R. A., & Fonseca, F. S. (2021). Smartphone Use Among High Level Swimmers Is Associated With Mental Fatigue and Slower 100- and 200- but Not 50-Meter Freestyle Racing. Perceptual and Motor Skills, 128(1), 390–408. https://doi.org/10.1177/0031512520952915
- Pageaux, B., & Lepers, R. (2018). The effects of mental fatigue on sport-related performance. Progress in Brain Research, 240, 291–315. https://doi.org/10.1016/BS.PBR.2018.10.004
- Fortes, L. S., De Lima-Junior, D., Fiorese, L., Nascimento-Júnior, J. R. A., Mortatti, A. L., & Ferreira, M. E. C. (2020). The effect of smartphones and playing video games on decision-making in soccer players: A crossover and randomised study. Journal of Sports Sciences, 38(5), 552–558. https://doi.org/10.1080/02640414.2020.1715181
- Fortes, L. S., Lima-Junior, D., Nascimento-Júnior, J. R. A., Costa, E. C., Matta, M. O., & Ferreira, M. E. C. (2019). Effect of exposure time to smartphone apps on passing decision-making in male soccer athletes. Psychology of Sport and Exercise, 44, 35–41. https://doi.org/10.1016/J.PSYCHSPORT.2019.05.001
- Dhir, A., Yossatorn, Y., Kaur, P., & Chen, S. (2018). Online social media fatigue and psychological wellbeing—A study of compulsive use, fear of missing out, fatigue, anxiety and depression. International Journal of Information Management, 40, 141–152. https://doi.org/10.1016/J.IJINFOMGT.2018.01.012
- Whaite, E. O., Shensa, A., Sidani, J. E., Colditz, J. B., & Primack, B. A. (2018). Social media use, personality characteristics, and social isolation among young adults in the United States. Personality and Individual Differences, 124, 45–50. https://doi.org/10.1016/J.PAID.2017.10.030
- Karim, F., Oyewande, A. A., Abdalla, L. F., Ehsanullah, R. C., & Khan, S. (2020). Social Media Use and Its Connection to Mental Health: A Systematic Review. Cureus, 12(6). https://doi.org/10.7759/CUREUS.8627
- Mortimer, K. (2017). Understanding Conspiracy Online: Social Media and the Spread of Suspicious Thinking. Dalhousie Journal of Interdisciplinary Management, 13(1). https://doi.org/10.5931/DJIM.V13I1.6928
- Li, L., Griffiths, M. D., Mei, S., & Niu, Z. (2020). Fear of Missing Out and Smartphone Addiction Mediates the Relationship Between Positive and Negative Affect and Sleep Quality Among Chinese University Students. Frontiers in Psychiatry, 11. https://doi.org/10.3389/FPSYT.2020.00877
- Reer, F., Tang, W. Y., & Quandt, T. (2019). Psychosocial well-being and social media engagement: The mediating roles of social comparison orientation and fear of missing out: Https://Doi.Org/10.1177/1461444818823719, 21(7), 1486–1505. https://doi.org/10.1177/1461444818823719
- Rus, H. M., & Tiemensma, J. (2017). Social media under the skin: Facebook use after acute stress impairs cortisol recovery. Frontiers in Psychology, 8(SEP), 1609. https://doi.org/10.3389/FPSYG.2017.01609/BIBTEX
- Bergagna, E., & Tartaglia, S. (2018). Self-Esteem, Social Comparison, and Facebook Use. Europe’s Journal of Psychology, 14(4), 831. https://doi.org/10.5964/EJOP.V14I4.1592
- Krasnova, H. (n.d.). BORIS. Retrieved May 4, 2022, from https://boris.unibe.ch/47080/
- Haferkamp, N., & Krämer, N. C. (2011). Social comparison 2.0: examining the effects of online profiles on social-networking sites. Cyberpsychology, Behavior and Social Networking, 14(5), 309–314. https://doi.org/10.1089/CYBER.2010.0120
- Olan, F., Jayawickrama, U., Arakpogun, E. O., Suklan, J., & Liu, S. (2022). Fake news on Social Media: the Impact on Society. Information Systems Frontiers, 1, 1–16. https://doi.org/10.1007/S10796-022-10242-Z/TABLES/6
- Albladi, S. M., & Weir, G. R. S. (2020). Predicting individuals’ vulnerability to social engineering in social networks. Cybersecurity, 3(1), 1–19. https://doi.org/10.1186/S42400-020-00047-5/FIGURES/3
- Majerczak, P., & Strzelecki, A. (2022). Trust, Media Credibility, Social Ties, and the Intention to Share towards Information Verification in an Age of Fake News. Behavioral Sciences, 12(2). https://doi.org/10.3390/BS12020051
- Martínez-Ferrer, B., Moreno, D., & Musitu, G. (2018). Are Adolescents Engaged in the Problematic Use of Social Networking Sites More Involved in Peer Aggression and Victimization? Frontiers in Psychology, 9(MAY), 801. https://doi.org/10.3389/FPSYG.2018.00801
- Kristinsdottir, K. H., Gylfason, H. F., & Sigurvinsdottir, R. (2021). Narcissism and Social Media: The Role of Communal Narcissism. International Journal of Environmental Research and Public Health, 18(19). https://doi.org/10.3390/IJERPH181910106