Two Things That Kill Your Strength

Stop Murdering Muscle and Performance


If building muscle and getting stronger is a priority, you need to stop sabotaging your progress. These two common practices will do it.

Nothing will wreck your ability to be strong and explosive faster than tons of steady state cardio. This is especially true with jogging. Trudging along for miles will not only burn through some of your hard-earned muscle and decrease your strength, it'll also make you less mobile in the process.

Plus the energy systems used and muscle fibers recruited for weight training and steady state cardio are on opposite ends of the spectrum.

Weight training primarily relies on your ATP-PC or phosphocreatine system, which is responsible for explosive bursts of energy lasting anywhere from 1-10 seconds. Near maximal and explosive resistance training, which rely on this energy system, recruit your fast twitch muscle fibers (type IIa and IIx). These fast twitch fibers have a great potential for hypertrophy.

Jogging, on the other hand, relies on your oxidative or aerobic energy system. This energy system dominates in repetitive activities lasting longer than three minutes and primarily stimulates your smaller, slower muscle fibers (type I). Long distance running can have a catabolic effect because once you run out of carbohydrate stores, you'll have to deaminate protein to create glucose for energy.

Studies have shown that endurance training reduces vertical jump power, explosive speed, and strength capabilities. It's been theorized that this could be because endurance training may degrade fast twitch fibers and replace them with slow twitch fibers, or cause enzymatic and neuromuscular changes found in slow endurance activities (1). For example, your type IIa fibers are oxidative-glycolytic, and have the ability to take on type I muscle fiber characteristics through endurance training.

If you're moving slow for a large majority of your training, you are training your body to move slowly. Hence the SAID (Specific Adaptations to Imposed Demands) principle.

There's also a high probability that you'll lose mobility and experience some joint pain if you up your mileage. Your joints go through a relatively small range of motion when jogging, and the repetitive impact will eventually take its toll.

What to Do Instead


I'm not against cardio, but I am against putting on excessive mileage through jogging if your goal is to build muscle. If you're needing some cardio for conditioning, fat loss, recovery, or heart health, here are two great options:

Tabata Cycling Workout

Tabata-style training generally means you do one or two different exercises, alternating 20 seconds of work with 10 seconds of rest for about 4 minutes.

Doing 8 all-out bouts of 20 seconds of work followed by 10 seconds of rest on a cycle ergometer has been shown to improve aerobic power similar to other methods of training with a significant decrease in the amount of time spent training (2). Just train really hard for four minutes, then call it a day.

Uphill Walking

Uphill walking is awesome because it has more of a muscle-building effect than jogging. Power walking uphill or on an incline treadmill does a great job of developing the backside of the body, especially your glutes. It's also significantly more joint friendly because there's less impact and eccentric stress.


In the short term, holding long stretches prior to strength training decreases your ability to be explosive and greatly reduces your ability to use stored elastic energy in the muscle.

In the long term, getting overzealous with your stretching protocol can actually deform or damage tendons and ligaments which impairs joint stability (1).

Explosive exercises like lifting use stored elastic energy in the muscle to help complete the movement. When you perform an eccentric contraction such as in the lowering portion of the squat, your muscles get pre-stretched as you go down.

This pre-stretch helps load your muscle similar to that of a rubber band. When your muscles get a pre-stretch prior to contracting, they're aided by the "series elastic component" (SEC) in your muscle to release tremendous amounts of stored energy upon muscle contraction.

If you've stretched the elasticity out of your muscle, you'll get significantly less aid from your SEC during strength exercises that start with an eccentric/negative contraction. This will inevitably prevent you from being able to lift as much weight.

Also, depending on how long you've stretched, you could change your state from being predominantly parasympathetic (rest and digest) to sympathetic (fight or flight).

Deep stretching for an extended period of time will put your body and mind into a relaxed state, which is the exact opposite of what you'd want if you're going to throw around some heavy weight.

What to Do Instead

Some mobility work is helpful, but static stretching is not the way to accomplish this. Soft tissue work and active dynamic stretches have been shown to improve mobility without losing the elastic properties of the muscle.

Spending a few minutes with a foam roller or lacrosse ball and doing a few "catch all" mobility movements will allow you to safely execute your exercises while preserving the ability to use your stretch reflex.

  1. Verkhoshansky YV et al. Chapter 1: Strength and The Muscular System. In Supertraining (pp. 57-58; 175). Verkhoshansky. Rome, Italy. December 7, 2009.
  2. Viana RB et al. Tabata protocol: A review of its application, variations and outcomes. Clin Physiol Funct Imaging. 2019 Jan;39(1):1-8. PubMed.
TJ Kuster is a certified athletic trainer (ATC) and certified strength and conditioning specialist (CSCS), specializing in mobility and injury prevention. He coaches at Method Sports Performance in Bloomington, IL.