How to combine cardio and resistance training

     When your lifting weights you do a set, rest, then do another set, complete desired sets then move on to another exercise then rinse, wash, repeat. This is an oversimplification of things. Exercise selection matters, number of sets, reps, rest, all matter depending on your goal. The goal is front and center for all those things. I would say that most folks who lift have a basic understanding of those variables. This post, however, is not entirely about resistance training rest cycles. 

    Today we will look at rest cycles for cardio. Cardio is an evil word for gym bros that typically consists of long, dreadful sessions on the treadmill or stair stepper. This doesn't have to be the case. Cardio can work side by side with resistance training without long, sustained cardio routines.

    If we look at basic science behind muscle fiber adaptations within resistance training and aerobic training, we notice that many of the adaptations are the opposite. For resistance training we notice that our muscles adapt to "fire" at once in response to a heavy load. While aerobic training causes muscles to "fire" at different rates and times to ensure muscles can last throughout the duration of training. We also know that during resistance training our muscle grow in thickness and diameter (thus causing hypertrophy). For aerobic training we know that muscles shift in function due to training. Type 1 and Type 2 remain the same, but the Type 2x and Type 2a adapt towards more endurance than explosiveness. These examples in itself are oxymoronic. If we want bigger muscles, then why do something that contradicts muscle growth?

    Here's how you can combine cardio and resistance training.

Intervals.

Yup, That simple.

    Ok, I lied. It's not that simple. The premise of it is, but a deeper look into intervals requires a deeper understanding of energy systems and goals. 

    If my goal is to get bigger, stronger, faster than my cardio needs to reflect that. Short duration sprints that cycle rest periods sounds very much like resistance training. When we are in the gym, we use rest periods to build back strength in our muscles in order to lift the weight again. Heavier the weight the longer the rest periods. Same with sprints. The higher intensity the longer we want to rest. 

    Working the phosphagen system we want to stay in the 5 seconds to 10 seconds work range. To hit sprints in that range in the gym it would be helpful to have long enough turf to sprint 10 seconds, treadmill without a motor, or air bike. Any equipment with a motor may not be able to cycle through in time for the intensity duration. The rest cycles are 1:12 to 1:20. This means that if I am exercising for 10 seconds then my rest period should be 120 seconds to 200 seconds (10x12 to 10x20). Sprint for 10 seconds then rest for at least 2 min. This enables the ATP-CP levels to rebuild, so full effort can be made for the duration of the sprint. Remember we are trying to get faster not necessarily build cardio for a marathon. We are matching our resistance training goals with cardio.

    Let's say we want to extend our sprints for a longer duration. Cool beans. This would shift the primary energy system from ATP-CP to fast glycolysis or anaerobic glycolysis. We are still sprinting, but now lactate threshold plays a factor. Instead of just running off fuel within our muscle cells we dabble into the Cori cycle. If we want to stay in this range, then 15 seconds to 30 second bouts would be ideal. Anything over 30 seconds can be conducted but its more lactate threshold training then speed. If we are training in the 15-30 second range, then our rest periods would be 1:3-1:5. For example, 30 second sprint would have a range of 90 seconds to 150 seconds (3x30 to 5x30). 

    These are two examples of how to blend cardio with resistance training. Also, conduct sprints first before tackling resistance training. Trying to sprint after resistance training will zap your energy during your cardio efforts.