From cycling, to running, to soccer, to swimming, aerobic exercise requires endurance so athletes can keep on truckin’ without losing steam. But it may not be as easy as running longer, swimming farther, or cycling a century. Here, we lay out some traditional ways to boost stamina along with sneakier ways to keep going stronger, longer.

Push it Real Good—The Need-to-Know

Endurance allows people to work out at a certain intensity or for an extended amount of time (hello, marathon!) The effect of endurance training on parameters of aerobic fitness. Jones, A.M. Carter, H. Department of Exercise and Sport Science, Crewe and Alsager Faculty, The Manchester Metropolitan University, England. Sports Medicine, 2000 Jun;29(6):373-86.. There are a number of factors that combine to create an athlete's "endurance profile," and two of the most important are VO2 max and lactate threshold. VO2 max, or the maximum rate at which an athlete's body can consume oxygen during exercise, is the most popular measurement of aerboic capacity (although it’s unclear if it’s necessarily the most accurate) Limiting factors for maximum oxygen uptake and determinants of endurance performance. Bassett, D.R., Howley, E.T. Department of Exercise Science and Sport Management, University of Tennessee, Knoxville TN. Medicine and Science in Sports and Exercise, 2000 Jan;32(1):70-84. Testing for maximum oxygen consumption has produced a brainless model of human exercise performance. Noakes, T.D. Research Unit for Exercise Science and Sports Medicine, Deaprtment of Human Biology, University of Cape Town, Cape Town, South Africa. British Journal of Sports Medicine, 2008 Jul;42(7):551-5. Epub 2008 Apr 18.. Although endurance ability is mostly a matter of genetics, maximal oxygen uptake can be improved with targeted training. High intensity interval training (HIIT) workouts have been shown to to do the trick, increasing athletes' VO2 max Aerobic high-intensity intervals improve VO2max more than moderate training. Helgerud J, Høydal K, Wang E, et al. Medicine and Science in Sports and Exercise. 2007 Apr;39(4):665-71.. Another piece of the endurance puzzle is the athlete's lactate threshold, or the level of exertion at which lactate accumulates in the muscles Lactate threshold concepts: how valid are they? Faude, O., Kindermann, W., Meyer, T. Institute of Sports Medicine, University Paderborn, Paderborn, Germany. Sports Medicine, 2009;39(6):469-90. Luckily, it's possible for virtually any athlete to improve both of these measures. To improve lactate threshold—and therefore the ability to workout harder for longer periods of time—Greatist Expert Noam Tamir says tempo runs may do the trick. Endurance athletes often have a higher proportion of slow-twitch muscle fibers, which power steady-state activities like running by using oxygen efficiently to generate more energy Maximal oxygen uptake and muscle fiber types in trained and untrained humans. Bergh, U., Thorstensson, A., Sjodin, B. et al. Medicine and Science in Sports, 1978 Fall;10(3):151-4. Running long can train slow-twitch muscles to fuel such workouts more efficiently and to fight fatigue more effectively. A continuous practice of long-distance running can also help convert fast-twitch muscles to slow-twitch muscles, which will enhance endurance.

Surefire Stamina—Your Action Plan

Try these tips to help bump up endurance a notch. With some smart training and nutrition guidance, that Ironman may totally be within reach!

• Rest up. To go long and hard, athletes need fresh muscles, says Greatist Expert John Mandrola: “Go hard on hard days; go easy on easy days; and never string hard days together without adequate rest.” Feeling fresh can help anyone go the distance.

• Eat right. When it comes to exercise nutrition, carbs are key, since the body uses glycogen for fuel when the goin’ gets tough Exercise and functional foods. Aoi, W., Naito, Y., Yoshikawa, T. Nutrition Journal, 2006 Jun 5;5:15.. Once glycogen runs out, the body turns to energy from other sources, and begins to burn fat. For extended cardio sessions, consume 30-60 grams of carbs every hour, depending on body weight. Studies have also found a mix of carbs and protein can enhance endurance performance and reduce muscle damage—win! Adaptation to a fat-rich diet: effects on endurance performance in humans. Helge, J.W. Copenhagen Muscle Research Centre, August Krogh Institute, University of Copenhagen, Denmark. Sports Medicine, 2000 Nov;30(5):347-57. Effects of diet on muscle triglyceride and endurance performance. Starling, R.D., Trappe, T.A., Parcell, A.C., et al. Human Performance Laboratory, Ball State University, Muncie, Indiana. Journal of Applied Physiology, 1997 Apr;82(4):1185-9. Effects of a carbohydrate-protein beverage on cycling endurance and muscle damage. Saunders, M.J., Kane, M.D., Todd, M.K. School of Kinesiology and Recreation Studies, James Madison University, Harrisonburg, VA. Medicine and Science in Sports and Exercise, 2004 Jul;36(7):1233-8. Effect of a carbohydrate-protein supplement on endurance performance during exercise of varying intensity. Ivy, J.L., Res, P.T., Sprague, R.C., et al. Department of Kinesiology and Health Education, The University of Texas, Austin, TX. The International Journal of Sport Nutrition and Exercise Metabolism, 2003 Sep;13(3):382-95.. That said, keep in mind that the best mix of carbohydrates, fat and protein varies considerably amongst athletes, says Mandrola. Experiment, experiment, and experiment some more to find the right combination for you.

• HIIT it up. It might sound crazy, but often less really is more. High intensity interval training—aka quick bouts of intense exercise—can help improve endurance in conjunction with traditional training Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance. Gibala, M.J., Little, J.P., van Essen, M., et al. Department of Kinesiology IWC AB122, McMaster University, Hamilton, Ontario, Canada. Journal of Physiology, 2006 Sep 15;575(Pt 3):901-11. Epub 2006 Jul 6. Aerobic high-intensity intervals improve VO2max more than moderate training. Helgerud, J., Hoydal, K., Wang, E., et al. Department of Circulation and Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway. Medicine and Science in Sports and Exercise, 2007 Apr;39(4):665-71.. Need some ideas on how to mix it up? Run some stairs or try a track workout for some speed. Just remember to get plenty of recovery after these workouts—they’re intense!

• Add some strength. When it comes to endurance training, variation is important. Resistance training can strengthen our bones, ligaments, tendons, and muscles—helping improve overall fitness and helping with that final sprint to the finish Effects of resistance training on endurance capacity and muscle fiber composition in young top-level cyclists. Aagaard P, Andersen J.L., Bennekou M, et al. Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark. Scandinavian Journal of Medicine and Science in Sports, 2011 Dec;21(6):e298-307. Mix up aerobic exercise with kettlebells, dumbbell, and bodyweight exercises to help improve stamina Compatibility of adaptive responses with combining strength and endurance training. McCarthy, J.P., Agre, J.C., Graf, B.K., et al. Biodynamics Laboratory, University of Wisconsin-Madison WI. Medicine and Science in Sports and Exercise, 5 Mar;27(3):429-36. Explosive-strength training improves 5-km running time by improving running economy and muscle power. Paavolainen, L., Hakkinen, K., Hamalainen, I., et al. KIHU-Research Institute for Olympic Sports, University of Jyväskylä, SF-40700 Jyväskylä, Finland. Journal of Applied Physiology, 1999 May;86(5):1527-33. Effect of resistance training regimens on treadmill running and neuromuscular performance in recreational endurance runners. Mikkola, J., Vesterinen, V., Taipale, R., et al. KIHU-Research Institute for Olympic Sports, Jyväskylä, Finland. Journal of Sports Sciences, 2011 Oct;29(13):1359-71. Epub 2011 Aug 22.

• Turn on the tunes. Could it be as easy as pumping up the volume? Listening to music has been shown to boost endurance performance while walking, so it doesn’t hurt to work out with some tunes. The mind-body connection is especially strong among endurance athletes, and any pick-me-up can help when the going gets tough Psychophysical and ergogenic effects of synchronous music during treadmill walking. Karageorghis, Cl. Mouzourides, D.A., Priest, D.L., et al. School of Sport and Eduction, Brunel University, West London, UK. Journal of Sport and Exercise Phychology, 2009 Feb;31(1):18-36..

• Work on what’s weak. People often find their fitness niche and stick to it. Instead, Mandrola advises people to mix it up in order to build endurance: Marathoners should work on speed, and flat-landers should stomp those hills. Getting to that personal best means working on what’s most challenging.

• Drink beet juice! Yup, it’s science. One study found nitrate-rich beets may help increase stamina up to 16 percent by reducing oxygen intake in athletes (It remains unclear if other nitrate-rich foods produce similar effects) Promoting functional foods as acceptable alternatives to doping: potential for information-based social marketing approach. James, R., Naughton, D., Petroczi, A. Journal of the International Society of Sports Nutrition, 2010 November 10.. So consider drinking some beet juice along with that bowl of pasta the night before race day. You never know. Just remember that beet juice can be high in sugar, so use in moderation.
• Train smart. The gradual adaption principle—that is, slowly and steadily increasing mileage and speed—is a great way to build endurance. There are ways to do this safely to avoid injury, from running on soft surfaces, to getting enough sleep and drinking tons of water.