If you’re working out with weights or doing resistance bands or even body weight resistance along with cardio, what we call cross-training, you can use supplements to help further your gains. In a previous blog I wrote about some of my favorites. Now I’d like to expand on this and suggests a few more that you should consider adding to your work-out regimen when it contains a mix of resistance and intervals.



As strange as it may seem, beets are gaining popularity as a workout supplement. Why beets? Science suggests beetroot may enhance exercise performance because it’s high in nitrate, a compound associated with increased blood flow. It seems nitrate may be particularly beneficial for amping up your ability to do intense workouts. In one study, soccer players who drank beet juice before doing high intensity intermittent running exercises performed better than those who drank placebo juice. Another study conducted in 2017 found nitrate-rich beet juice can increase oxygen efficiency in cycling when a person is exercising at less than maximum intensity. In the study, athletes who received nitrate-rich beetroot juice performed better in a 1,500 meter time trial but not a 10,000 meter one, suggesting beetroot may enhance performance for shorter distances at a high work rate but maybe not for long distances at a lower work rate.



As explained by bodybuilding.com, the high-intensity movement workouts create a buildup of hydrogen ions, which get in the way of muscle contraction and cause you to feel fatigued. They suggest supplementing with beta-alanine, an amino acid that helps your body produce carnosine. Carnosine can eliminate excess hydrogen ions in your body, and research indicates it may boost performance in the process. According to a 2010 review, “Supplementation with beta-alanine has been shown to increase muscle carnosine content and therefore total muscle buffer capacity, with the potential to elicit improvements in physical performance during high-intensity exercise.” The experts at bodybuilding.com recommend taking 3-6 grams of beta-alanine per day for at least 28 days.



Coffee drinkers are no doubt aware of the way it boosts your ability to accomplish both mental and physical tasks, so it’s not surprising caffeine is frequently used as a workout supplement. As reported by Healthline, caffeine has been shown to increase power output during activities like sprinting, cycling, and weight training. Research suggests it may also enhance endurance during long-distance runs and bike rides. In one study where seven elite runners performed two trials each of running and cycling to exhaustion, those who took a caffeine supplement beforehand had significantly improved times in both sports compared to a placebo group. Just remember that, although it’s certainly safe when consumed in moderation, caffeine can negatively affect your health if you overdo it. The Crossfit magazine BoxLife says around 250 milligrams per day is considered to be moderate caffeine intake, adding that the amount of caffeine shown in studies to improve performance is between 1.5 and 4 milligrams per pound of bodyweight taken one hour before you exercise.


Branched-chain Amino Acids (BCAAs)

Collectively known as branched-chain amino acids because they possess a similar structure, leucine, isoleucine, and valine are essential amino acids. Fitness enthusiasts like BCAAs because they’re reportedly useful for preventing the breakdown of muscle protein, meaning they can help reduce soreness when taken before workouts. The results of one study published in the Journal of Nutrition suggest ingesting 5 – 10 grams of BCAAs before exercise reduces delayed-onset muscle soreness and muscle fatigue for several days after. Just make sure you are buying BCAAs from a reputable source, like FullScript.



According to bodybuilding.com, creatine is a popular supplement among athletes and fitness enthusiasts because it appears to be safe and it works. Research shows creatine improves strength, increases lean body mass, and enhances performance. In one study, participants who took creatine while following a weight-training program for ten weeks increased their one-rep squat max by 25% compared to a placebo group. While creatine may not be effective for endurance aerobic exercise, the Mayo Clinic says it’s beneficial for short bursts of intense exercise. Many experts recommend using creatine powder mixed with fruit juice to boost the uptake of creatine into your muscles.


B Vitamins

B vitamins—thiamin, riboflavin, niacin, pantothenic acid, B-6, biotin, folic acid, and B-12—play an important role in the body’s process of converting protein and sugar to energy as well as the repair and production of cells. A study conducted at Oregon State University and published in the International Journal of Sport Nutrition and Exercise Metabolism found athletes and other active people who lack B vitamins may not perform as well during high intensity exercise and have a decreased ability to repair and build muscle compared to those with nutrient-rich diets. As researcher Melinda Manore explained in a press release, “Many athletes, especially young athletes involved in highly competitive sports, do not realize the impact their diets have on their performance.” To make sure you’re getting the most bang for your buck, look for methylated forms of B vitamins that your body can absorb and use more readily.


Fish Oil

There’s a reason I include fish oil on my list of five supplements everyone should take. Not only are the omega-3 fatty acids found in fish oil important for cardiovascular and neurological health, they may help you recover more quickly after workouts, increase muscle mass, and more. As reported in Men’s Fitness, the profound anti-inflammatory effects of omega-3s can speed healing of the microscopic tears that lead to bigger muscles. They may also alleviate post-workout soreness. In a study published in the Clinical Journal of Sports Medicine, subjects who were given omega-3 supplements before exercising reported less soreness and better range of motion 48 hours later compared to placebo and control groups.

Protein Powder

Although you’ll ideally get enough protein from your diet, protein powders are a convenient way to give yourself a post-workout boost. But with so many choices on the market, how do you know which one will work for you? CrossFit website The Box advises reading the label carefully. Amino acids like taurine and glycine might sound good, but they’re often added by companies in an effort to falsely inflate a product’s protein content. The Box suggests looking for leucine, an amino acid that appears to trigger muscle-protein-manufacturing systems. Personally, I prefer a “clean” product like the grass fed, organic protein powders from Tera’s Whey. They’re all natural, high quality, and they taste amazing—especially the Bourbon Vanilla flavor. For a vegan protein source, I recommend Vega Sport protein powder with pea and pumpkin seed protein. www.myVega.com.



This is another one of my top five supplements. Acetyl-L-carnitine is a frequently-depleted enzyme that plays a critical role in the Krebs cycle, which powers everything in your body by converting food into energy. Studies have shown supplementing with carnitine may improve your performance and speed recovery from strenuous workouts. Muscle & Strength suggests taking 1-2 grams of twice a day can help you exercise harder and longer. I generally tell my patients to take 1,000 milligrams daily to boost overall energy.

There you have it, more of the best supplements for your cross-training or Orange Theory workouts. You can also read my recommendations for pre-workout supplements here

Are you getting the nutrients you need for long-term health? Download my Top 10 Supplements For Men PDF to learn about the most critical supplements you need.

Myles Spar, MD, MPH is board certified in Internal Medicine and in Integrative Medicine. As a clinician, teacher and researcher on faculty of two major medical centers, he has led the charge for a more proactive, holistic and personalized approach to care that focuses on cutting edge technology and preventative care. Dr. Spar has been a consultant with the NBA, presented a TEDx Talk, appeared on national television, and been featured in publications such as the Men’s Journal and the Los Angeles Times. He was most recently National Medical Director and Chief Medical Officer of a national medical practice, but is available to consult with individual patients interested in a personalized approach to optimal performance and health.