Bodybuilding legend Arnold Schwarzenegger is taking a hard look at two popular pre-workout supplements. In an Arnold\u2019s Pump Club newsletter shared on Dec. 10, 2025, he weighed the performance boost impact offered by L-arginine and citrulline malate.\u00a0<\/p>\n
As a seven-time Mr. Olympia<\/a> champion, Arnold Schwarzenegger<\/a> was after any edge he could get onstage. For many athletes today, pre-workout formulas have become a go-to. Some are caffeinated, whereas others are simply focused on maximizing pump.\u00a0<\/p>\n Pre-workout supplements<\/a> can be a fantastic tool. Users often include them before exercise to aid endurance<\/a>, strength<\/a>, and power. Below, Schwarzenegger examines whether these substances fall short of their promised claims.\u00a0<\/p>\n Arnold Schwarzenegger Discusses Whether Common Pre-Workout Ingredients Are Actually Helping Your Workouts\u00a0<\/p>\n In the newsletter, Schwarzenegger examined a new controlled study that saw participants use L-arginine and citrulline malate.\u00a0<\/p>\n \u201cDo These Two Pre-Workout Ingredients Do Anything? This New Study Put It to the Test Though they are popular options, Schwarzenegger noted that the study found no performance boosts concerning CrossFit, cardio, or cycling sprints.\u00a0<\/p>\n Get Fitter, Faster<\/p>\n Level Up Your Fitness: Join our \ud83d\udcaa strong community in Fitness Volt Newsletter. Get daily inspiration, expert-backed workouts, nutrition tips, the latest in strength sports, and the support you need to reach your goals. Subscribe for free!<\/p>\n Please wait…<\/p>\n You’re In! Let’s Crush Your Fitness Goals Together<\/p>\n Expect expert-backed workouts, nutrition advice, the latest in strength sports, and a whole lot of motivation heading your way.<\/p>\n Subscribe Another Email<\/p>\n \u201cThe surprising finding: despite their popularity, l-arginine and citrulline malate didn\u2019t improve performance in CrossFit, cardio, or cycling sprints.\u201d<\/p>\n Looking at 46 individuals, there were no differences in heart rate, rounds completed, or performance.\u00a0<\/p>\n \u201cResearchers recruited 46 healthy, trained participants and put them through three challenging workouts \u2014 a Wingate cycling sprint, the CrossFit \u201cCindy\u201d workout, and the Harvard Step Test \u2014 after giving them either a placebo or a combination of L-arginine and citrulline malate (common nitric-oxide\u2013boosting ingredients found in many pre-workouts).<\/p>\n There was no difference in rounds completed, heart rate, or overall performance between the CrossFit workouts. For the Harvard Step Test, there was also no difference in cardio fitness or recovery. And on the Wingate sprints, no boost in peak or average power.\u201d<\/p>\n Schwarzenegger believes the lack of benefits could have been due to the goals tested.\u00a0<\/p>\n \u201cWhy didn\u2019t the supplements work? The authors believe there are a few possible explanations. For one, they just might not be effective for the goals tested. While citrulline and l-arginine are designed to increase blood flow, other studies have been inconclusive about how much they improve performance.\u201d<\/p>\n Additionally, he shared that nitric-oxide boosting supplements can take longer to work and are often more effective with consistent use.\u00a0<\/p>\n \u201cIt\u2019s also popular that the ingredients may take longer to work. Nitric-oxide\u2013boosting supplements might be more effective with regular, chronic use rather than short-term use for individual hard workouts. Other studies have suggested that the combination of arginine and citrulline could help with repeated-sprint performance, workouts that require more volume (think higher reps), and reducing the perceived effort of a workout.\u201d<\/p>\n While he admits they can help with the pump, Schwarzenegger isn\u2019t sold on their performance payoff just yet.\u00a0<\/p>\n \u201cIf you\u2019re buying arginine or citrulline hoping for an instant performance boost, this study suggests you may not notice any real difference. Your pump might feel good, but the performance payoff might not be there.\u201d\u00a0<\/p>\n This wasn\u2019t Schwarzenegger\u2019s first time scrutinizing supplements. He recently called out a \u2018very disturbing\u2019 fact about pre-workouts, noting that in one study, 89% of supplements didn\u2019t contain the ingredients<\/a> they promised on the label.\u00a0<\/p>\n Even in retirement, Schwarzenegger doesn\u2019t miss a chance to examine the latest fitness research. When it comes to arginine or citrulline, he\u2019s unsure if they are actually providing substantial benefits.\u00a0<\/p>\n
If you\u2019ve ever taken a scoop of pre-workout and wondered, \u201cIs this helping\u2026or is it just making my face tingle?\u201d \u2014 you\u2019re not alone. Supplements promise more reps, more power, and better endurance. But a new controlled study took a hard look at two popular ingredients (L-arginine and citrulline malate) to see if they deliver when it counts.\u201d<\/p>\n