Running: Ideal for Optimal Body Composition?
Do you like to run? Which burns more fat—RUNNING or SPRINTING? Fasted or "fed?" Let's discover what the SCIENCE has to say.....
UNFORTUNATELY, running CAN cause MUSCLE to be used as fuel, especially if you are in a Caloric deficit and not resistance training to prevent wasting muscle; recent studies strongly imply that low-impact types of cardiovascular exercise are more friendly to preserving optimal muscle mass while in a Caloric deficit and resistance training.[1] Furthermore, many bodybuilding coaches (mine included) have reported increased muscle loss specifically due to running and therefore recommend the stair mill, uphill walks on the treadmill, cycling, rowing, or the elliptical as more “muscle-friendly” alternatives. I have, however, noticed a drastic increase in calf strength whenever I re-introduce running into my training regimen.
HIIT vs. LISS: High-Intensity Interval Training (HIIT) has been shown to burn fewer Calories than Low-Intensity Steady State (LISS) while the cardio is being performed; however, HIIT—in the form of full-out sprints with short, intermittent recovery periods in this case—increases your Calorie burn post-exercise by stimulating “Excess Post-Exercise Oxygen Consumption” (EPOC), also called the “after-burn.” Steve Barrett in his book The HIIT Bible: Supercharge your Body and Brain states on p.31: “EPOC makes the body continue to absorb oxygen at a measurable higher rate following a HIIT session which results in the stored fat being torched for hours after your have finished a workout.”[2] In fact, HIIT has been shown to conservatively burn as much fat throughout the day as LISS after factoring in the EPOC.[3],[4] Additionally, science shows HIIT is also naturally more muscle and strength-sparing[5]. Moral of the story: It depends on your goal.
FASTED vs. "FED:" A study between “fasted” and “fed” cardio with all other factors including Calories, running type, and duration showed no difference in fat loss or muscle retention.[6] Do you feel more energy on an empty stomach or after a meal?
Running for BODYBUILDING PREP: Arnold Schwarzenegger and many of the old-school legends of the Classic Era would run on contest prep, believing that in addition to fat loss, it would "lengthen the calves." Because of its catabolic nature, most of my cardio is done with lower-intensity alternatives; however, going for short, daily jogs with Zion while meditating to Bible scripture and praying has become an enjoyable morning ritual for the both of us. I can feel a healthy serotonin boost every time we run together, and when it comes to optimizing muscle, the importance of hormonal health cannot be overstated! My coach always taught me that all science aside, whatever helps your circadian rhythm and gives you a good night sleep is typically a net win!
TIMING: Scientifically speaking, the most optimal time to run is POST-WORKOUT. This is the time of day when your natural testosterone, HGH, DHEA, and several other steroid hormones are at their peak,[7] all of which favor ideal body composition, therefore encouraging your body to burn fat while minimizing the concern of losing your hard-earned muscle to be used as fuel. Personally, however, morning jogs are a devotional opportunity to begin the day with praise & worship; after my workouts, I'm typically in a creative, peak state of mind--an ideal time for content creation and social media, both of which can be done on my iPhone while performing LISS cardio in the form of a stairmill or treadmill. Therefore most of my running is done fasted in the morning, but there's nothing wrong with an occasional mid-day run when the mood, weather, and Zion are all telling me it's time to run!
SUMMARY: Running is a healthy fat-loss option. Like intermittent fasting, if it is something you truly enjoy, it can be incorporated wisely to avoid the disadvantages of more "muscle-friendly" types of LISS cardio such as uphill walks on a treadmill, stair climbing, elliptical, or bicycle, allowing for variety and flexibility in your training program.
SOURCES:
[1] YouTube, Abby Pollock,, 8 May 2021, https://www.youtube.com/watch?v=ASUcmAkflPE&t=793s. 4:30. Accessed 16 June 2022.
[2] Barrett, Steve. The HIIT Bible: Supercharge Your Body and Brain, p. 31, Bloomsbury Publishing and Steve Barrett © 2017
[3] Melanson, EL, Sharp, TA, Seagle, HM, Horton, TJ, Donahoo, WT, Grunwald, GK, Hamilton, JT, and Hill, JO. “Effect of Exercise Intensity on 24-Hour Energy Expenditure and Nutrient Oxidation.” J Appl Physiol (1985) 92:1045-1052, 2002.
[4] Saris, WH and Schrauwen, P. “Substrate Oxidation Difference Between High and Low Intensity Exercise Are Compensated Over 24 Hours in Obese Men.” Int J Obes Relat Metab Disord 28:759-765, 2004.
[5] Wilson, JM, Marin, PJ, Rhea, MR, Wilson, SM, Loenneke, JP, and Anderson, JC. Concurrent training: “A Meta-Analysis Examining Interference of Aerobic and Resistance Exercise. J Biol Chem 39:943-952, 1941.
[6] Schoenfeld, BJ, Aragon, AA, Wilborn, CD, Krieger, JW, and Sonmez, GT. “Body Composition Changes Associated with Fasted Versus Non-Fasted Aerobic Exercise.” J Int Soc Sports Nutr 11:54, 2014.
[7] Timón Andrada R, Maynar Mariño M, Muñoz Marín D, Olcina Camacho GJ, Caballero MJ, Maynar Mariño JI. “Variations in Urine Excretion of Steroid Hormones After An Acute Session and After a 4-week Programme of Strength Training.” Eur J Appl Physiol. 2007 Jan;99(1):65-71. doi: 10.1007/s00421-006-0319-1. Epub 2006 Oct 19. PMID: 17051372.