By Elliot Fisher MS, ATC, CSCS, PES
To be more physically fit, it is important to become bigger, faster, and stronger. This is important for general health, as well as athletic performance. To do this, both resistance training and endurance training are used. There is evidence that concurrently training with both resistance and endurance exercise may lead to less overall progress.(1) In this article, we will take a deeper look into the interactions between these two types of training and how to structure them for maximum progress.
mTOR vs. AMPK
To reach a certain goal, a specific stimulus must be applied. For example, if you want to become stronger it would be better to lift weights than to run, and if you wanted to become a better runner it would be better to run than to lift weights. This makes sense logically, but on a physiological level this is true due to different biological pathways that are activated with different exercise. Resistance training activates mammalian target of rapamycin (mTOR) which helps build muscle and strength by increasing muscle protein synthesis. While endurance activities increases 5′ adenosine monophosphate-activated protein kinase (AMPK) which helps increase endurance based activities and increases catabolic activity (tissue breakdown). One issue that occurs with concurrent training is that AMPK will inhibit the mTOR pathway.(2) Meaning if resistance training and endurance training are done together there will be less strength and size adaptations because of the endurance stimulus. AMPK will inhibit mTOR, however the opposite is not true. The mTOR pathway does not seem to inhibit AMPK, and actually seems to enhance the overall adaptation to endurance activity.(1)
Another consideration in sport physiology is fatigue. Fatigue refers to the decrease in performance from accumulated stressors. If multiple training styles or sessions are performed often, fatigue can accumulate and decrease performance and overall adaptations to exercise. This means too much resistance training could take away from endurance adaptations if it is done too often, regardless of the typical advantages it brings. Additionally, when structuring a workout, the main goal of the individual should determine which style of training should come first (endurance athletes – endurance work first, strength athletes – resistance exercise first). It is also BEST if these two training modalities can be performed at different times in the day (such as AM and PM workouts) to manage fatigue.
When structuring a training or exercise program, a needs analysis should be conducted in order to dictate what training should be done and when. A couple of considerations include the following. To become the biggest or strongest, it is smart to eliminate cardio from training in order to maximize the adaptations from resistance exercise.1 To be better at endurance activity, some resistance training can help increase VO2Max.1 For overall health and wellbeing, a mixture of both training styles should be incorporated.(3,4) For athletes, depending on relative strengths and weaknesses in performance should dictate what training modalities should be incorporated. When training for physique or body composition, both should be used, resistance training to build lean mass, and endurance activity to decrease fat mass.
Wilson, J. M., Marin, P. J., Rhea, M. R., Wilson, S. M., Loenneke, J. P., & Anderson, J. C. (2012). Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises. The Journal of Strength & Conditioning Research, 26(8), 2293-2307.
Nader, G. A. (2006). Concurrent strength and endurance training: from molecules to man. Medicine and science in sports and exercise, 38(11), 1965.
Mann, S., Beedie, C., & Jimenez, A. (2014). Differential effects of aerobic exercise, resistance training and combined exercise modalities on cholesterol and the lipid profile: review, synthesis and recommendations. Sports Medicine, 44(2), 211-221.
Church, T. S., Blair, S. N., Cocreham, S., Johannsen, N., Johnson, W., Kramer, K., … & Sparks, L. (2010). Effects of aerobic and resistance training on hemoglobin A1c levels in patients with type 2 diabetes: a randomized controlled trial. Jama, 304(20), 2253-2262.