Contributed by Byron Fergerson, M.D.  What is VO2 Max?  VO2 Max measures the capacity of your body to process oxygen. While a number of factors contribute to performance in endurance sports like running, athletes with a high VO2 Max will generally be able to sustain higher pace and output compared to athletes with lower VO2 Max.   VO2 Max is a measurement of an athlete’s ability to utilize oxygen, which is one of the most important factors in an athlete's endurance. Let’s double click on the physiology of VO2 Max and why it’s an important predictor of performance for runners and other endurance athletes. Dr. Gregory Lewis is a Professor of Medicine at Harvard Medical School and Director of the Cardiopulmonary Exercise Testing Lab at Massachusetts General Hospital. He explains, “Peak VO2 has such important long-term health implications that its assessment has been suggested for use as a '5th vital sign by the American Heart Association in addition to heart rate, body temperature, breathing rate, and blood pressure”.  He continues, "Improvements in peak VO2 can be achieved throughout the life course by increasing physical activity.  In the Framingham Heart Study of community-dwelling middle-aged adults, we found that 5% higher peak VO2 was achieved with either increasing moderate to vigorous exercise by 17 minutes a day, increasing walking steps by 4,300 per day which is about 55 minutes of walking, or decreasing daily sedentary time by 249 minutes per day." (Nayor, et. al. 2021) The Physiology of VO2 Exercise is powered by mitochondria inside muscle cells. These microscopic power plants convert the body’s resources into the energy that muscle cells use to function. They can do their jobs aerobically by converting oxygen and fat reserves into power at low to moderate intensity exercise. Or, as exercise intensity increases, mitochondria shift to an anaerobic process which does not utilize oxygen, but can rapidly meet the energy demands of muscle for short periods. We accumulate lactic acid in muscle during anaerobic respiration, which contributes to “the burn” and quickly becomes unsustainable without dialing the effort back into an aerobic zone or stopping to rest. A higher VO2 score correlates with the ability to sustain a high level of output for long durations. An athlete with high VO2 Max can generate more power aerobically before crossing into their anaerobic threshold. For example, the faster someone can run before crossing that threshold means they will be able to sustain a higher level of performance than someone who maxes out their ability to process oxygen at a slower pace. That is why VO2 Max is still an excellent predictor of endurance and performance 100 years after it was discovered. VO2 Max can be influenced by several factors: Lung capacity and heart volume: Healthy lungs with higher volume can inhale more air and oxygen with each breath. And a healthy heart with relatively larger volume can pump more oxygenated blood to muscles. Both contribute to a higher VO2 score. Capillary network: These smallest blood vessels interweave throughout the body and deliver oxygenated blood to muscles and organs. The more capillaries you grow, equates to more efficient delivery of oxygen to muscle cell mitochondria, and a higher VO2 score. Muscle efficiency: The number of mitochondria inside muscle cells, and their efficiency at utilizing oxygen and other resources to power muscles impacts efficiency. The better your mitochondrial function, the more efficient your muscle becomes, and the higher your VO2 score goes. To Increase VO2 Max, a rigorous conditioning program will balance intense exercise with longer duration and recovery. The goal is to create adaptations in the lungs, heart, capillaries and muscle cells that will increase your ability to utilize oxygen and improve endurance.  6 Tips To Improve VO2 Max Interval Training:  Incorporate high-intensity interval training (HIIT) into your running training. This involves alternating between short bursts of intense running and periods of rest or lower-intensity activity. HIIT has been shown to be highly effective in increasing VO2Max Progressive Overload:  Gradually increase the intensity and duration of your workouts to challenge your cardiovascular system. This can be achieved by progressively increasing your running speed, distance, or incorporating more challenging terrains. Consistent and gradual overload is key to improving VO2Max over time. Long Runs:  Include longer, steady-state runs in your training regimen. These sustained efforts at a moderate intensity help improve aerobic capacity and endurance, contributing to an increase in VO2Max. Aim for at least one or two long runs per week to build a strong aerobic base. Cross-Training:  Incorporate cross-training activities that engage different muscle groups and cardiovascular systems. Activities such as cycling, swimming, or rowing can complement your running routine and provide a new stimulus for cardiovascular adaptation, ultimately helping to boost VO2Max. Consistency:  Sticking with your training over time is the key to improving VO2Max because the body adapts incrementally and gradually. Allowing time to rest and recover and avoiding abrupt changes can help reduce symptoms of overtraining or injuries. Aim for a balanced mix of different types of runs, including intervals, tempo runs, and long runs, to address various aspects of your cardiovascular fitness The Importance of Recovery After VO2 Max Training Dr. Lewis again, "The body’s  metabolic network changes abruptly in response to even a brief 10 minute bout of vigorous exercise.  Focusing on recovery from metabolic excursion during exercise can help support the goals of athletes training to improve VO2 Max." Particularly after high intensity interval training or long duration bouts of exercise exceeding several hours, muscles need to replenish glycogen energy reserves with a high amount of carbohydrates. Athletes training for VO2 Max for over 60 minutes at moderate to high intensity should target about 10g of Carbs for every 11 lbs of body mass within the first 30 minutes of completing a workout and again at 2 hours and 4 hours post workout. To rehydrate, about 1-2 cups of water is recommended for every pound of water weight lost during exercise. And electrolyte replacement may also help assist recovery, especially if the exercise involved heavy sweating. Including 1g of complete Protein for every 3-4g of Carbohydrates will work synergistically to help the body accelerate glycogen replacement. This protein also supports muscle recovery and growth post workout. Read more about post workout recovery for Runners and Crossfitters for additional detail about distance and power endurance training and recovery. What Is A Good VO2 Max By Age and Gender? Getting an accurate VO2Max score is not a simple task! There are various formulas to estimate VO2 Max. But the most reliable test involves a controlled bout of very high intensity exercise in a lab. If you’re unlucky enough to have ever taken a VO2 Max test, you can compare your score to a database of U.S. VO2 Max scores by age and gender (Fitness Registry and the Importance of Exercise National Database - FRIENDS)  VO2 Max Values by Age and Gender   VALUES(ML O2/KG/MIN) AGE GROUP 10TH PERCENTILE 50TH PERCENTILE 90TH PERCENTILE 95TH PERCENTILE MEN 20-29 32.1 48.0 61.8 66.3 30-39 30.2 42.2 56.5 59.8 40-49 26.8 37.8 52.1 55.6 50-59 22.8 32.6 45.6 50.7 60-69 19.8 28.2 40.3 43.0 70-79 17.1 24.4 36.6 39.7 WOMEN 20-29 23.9 37.6 51.3 56.0 30-39 20.9 30.2 41.4 45.8 40-49 18.8 26.7 38.4 41.7 50-59 17.3 23.4 32.0 35.9 60-69 14.6 20.0 27.0 29.4 70-79 13.6 18.3 23.1 24.1   Sample Training Plans To Increase VO2 Max High intensity intervals are key to trigger adaptations in muscle that lead to more efficiency and higher VO2 Max. Generally a 1:1 ratio of exertion and rest is a good pace to start. When training for endurance the high intensity workouts will take you to within 90% of max heart rate and should be 1 or 2 days a week tops. Intermingle HIIT (High intensity interval training) with long duration lower intensity sessions, some cross training, some strength, stretching, and plenty of rest. Recovery from high intensity endurance training takes longer, so pay attention to your body if you’re feeling sore or fatigued a day later and ease back until you’re fully recovered.  Remember,  5-15 minutes of warmup and cool down are essential to performance and injury prevention whenever attempting any high intensity VO2 Max interval training.  Here’s a couple of ideas for high intensity interval workouts: Run hard for two minutes, recover for two minutes, repeating 5 to 10 times. To improve your VO2 max, keep adding a minute every week or two until you're working hard for six to eight minutes 2 to 3 times. A higher intensity workout involves shorter sprints and shorter rest for more advanced runners. After warming up, run 30 seconds at 75% intensity, then jog 30 seconds at 25% intensity for 5 reps (5 minutes total). Jog lightly for 1 minute to recover. Repeat the sequence 2 more times. Cross training is a great way to push the intensity by quickly getting outside your aerobic zone. The rowing machine is an excellent way to cross train because it engages over 85% of the body’s muscle groups via low impact movement.  Try this interval ladder while taking 1:1 rest intervals. Set the fan between 3-5 so you can sustain a cadence between 24 - 30 strokes per minute while also becoming breathless by the end of each piece. Do 1:00 minute all-out, then paddle lightly for 1:00 min of rest. The next interval is 2:00 minutes on with 2:00 rest….  Go up the ladder to 4:00 minutes of work, and then back down the ladder. To make it harder try keeping your rest interval constant at 2:00 minutes, or try taking your stroke rating up 2 beats each step up the ladder and then back down as you descend. Supplements That May Support VO2 Max Epicatechin:This antioxidant micronutrient is found in certain foods like dark chocolate and green tea. It has been extensively studied for its potential to support cardiovascular health which relates to VO2Max. Research suggests epicatechin may enhance exercise performance by promoting the dilation of blood vessels, leading to improved blood flow and oxygen delivery to working muscles. A study of epicatechin supplementation in mice resulted in increased capillary density and improved exercise capacity, suggesting a potential positive impact on aerobic performance (Ramirez-Sanchez, 2014). Another study showed that epicatechin supplementation in humans stimulated mitochondrial biogenesis - or the formation of new mitochondria inside muscle cells (Craig et al., 2015). Increasing the population of mitochondria in muscle cells is one adaptation to endurance training that contributes to increased VO2Max by making muscles more efficient at utilizing oxygen. Iron:Iron is a component of hemoglobin, the protein responsible for transporting oxygen in blood. Adequate iron levels support the body's ability to transport and deliver oxygen to working muscles, which can affect VO2Max. Iron deficiency can lead to reduced oxygen-carrying capacity, negatively affecting endurance and performance. (Solberg, et. al., 2007) Vitamin B12:Vitamin B12 is essential for the production of red blood cells, which are crucial for oxygen transport. Maintaining adequate levels of vitamin B12 supports the synthesis of DNA and the formation of healthy red blood cells, indirectly influencing VO2Max. Deficiencies in vitamin B12 can lead to anemia and reduced oxygen-carrying capacity (Carmel, 2008). Omega-3 Fatty Acids:Omega-3 fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have anti-inflammatory effects and contribute to cardiovascular health. Reduced inflammation and improved cardiovascular function positively impact overall endurance and may support an increase in VO2Max. Omega-3 supplementation has been linked to enhanced exercise performance and cardiovascular fitness (Jeromson et. al., 2015). Carbohydrates:Carbs are the primary energy source during aerobic exercise. Ingesting an adequate amount of carbohydrates ensures glycogen stores are optimized, providing the necessary fuel for sustained effort. Carbohydrate intake before and during prolonged exercise helps delay fatigue, supporting an individual's ability to maintain a higher VO2Max for an extended period (Burke et. al., 2011).  It's important to note that while these nutrients may play a role in supporting VO2Max, individual nutritional needs vary. This article does not constitute medical advice. Individuals should consult a registered dietitian or healthcare professional to tailor dietary recommendations based on individual requirements and health status. Rapidly Replenish and Rehydrate: Maximize Glycogen Replenishment 28g Carbohydrates 1000+mg of Electrolyte Replenishment Optimal protein composition for endurance training Drink immediately within 30 minutes after exercise to quick-start recovery Supplemented for ACTIVE RECOVERY: 450mg of plant bio-nutrients Epicatechin & Quercetin Supports Aerobic adaptations in muscle linked to VO2 Max and Endurance Aids regulation of exercise induced oxidative stress and inflammation response Promotes resilient muscle when endurance training at high intensity or high volume   References: Nayor M, Chernofsky A, Spartano NL, Tanguay M, Blodgett JB, Murthy VL, Malhotra R, Houstis NE, Velagaleti RS, Murabito JM, Larson MG, Vasan RS, Shah RV, Lewis GD. Physical activity and fitness in the community: the Framingham Heart Study. Eur Heart J. 2021 Nov 21;42(44):4565-4575. doi: 10.1093/eurheartj/ehab580. PMID: 34436560; PMCID: PMC8633734. Brossette T, Hundsdörfer C, Kröncke KD, Sies H, Stahl W. Direct evidence that (−)-epicatechin increases nitric oxide levels in human endothelial cells. Eur J Nutr. 2011;50(7):595-599. doi:10.1007/s00394-011-0172-9  Moreno-Ulloa A, Miranda-Cervantes A, Licea-Navarro A, et al. (-)-Epicatechin stimulates mitochondrial biogenesis and cell growth in C2C12 myotubes via the G-protein coupled estrogen receptor. Eur J Pharmacol. 2018;822:95-107. doi:10.1016/j.ejphar.2018.01.014 Ramirez-Sanchez, I., De los Santos, S., Gonzalez-Basurto, S., Canto, P., Mendoza-Lorenzo, P., Palma-Flores, C., ... & Meaney, E. (2014). (−)-Epicatechin improves mitochondrial-related protein expression and function in aging. The Journal of Gerontology Series A: Biological Sciences and Medical Sciences, 69(8), 879-889 Craig DM, Ashcroft SP, Belew MY, et al. Utilizing small nutrient compounds as enhancers of exercise-induced mitochondrial biogenesis. Front Physiol. 2015;6:296. doi:10.3389/fphys.2015.00296 Solberg A, Reikvam H. Iron Status and Physical Performance in Athletes. Life (Basel). 2023 Oct 2;13(10):2007. doi: 10.3390/life13102007. PMID: 37895389; PMCID: PMC10608302. Carmel, R. (2008). Cobalamin, the stomach, and aging. The American Journal of Clinical Nutrition, 89(2), 693S-696S  Jeromson, S., & Gallagher, I. J. (2015). Omega-3 Fatty Acids and Skeletal Muscle Health. Marine Drugs, 13(11), 6977–7004. Burke, L. M., Hawley, J. A., Wong, S. H. S., & Jeukendrup, A. E. (2011). Carbohydrates for training and competition. Journal of Sports Sciences, 29(sup1