The 5 Biggest Training Mistakes Stopping You From Building Lean Muscle

Are you in the gym a lot... but not making progress?

Nothing is more frustrating than wasting months of your time, with no progress to show for your effort.

I've been there. Luckily, all that frustration was a blessing in disguise.

The huge amount I've learned from all of my mistakes has allowed me to help hundreds of clients - both online and in-person - build the leanest, strongest, and most confident version of themselves. All while avoiding MY mistakes.

So, if you feel stuck in the gym right now, read on. These are the most common mistakes new online clients are making that's holding their progress back:

1. You're Focusing Too Much On Weight... Or Too Much On The Mind-Muscle Connection

For years of my leg training, I made no progress.

Don't get me wrong, I was trying HARD to build my skinny legs.

Over and over again, I had heard...

"If you want to get big, you need to lift heavy ass weight, bro."

So the sole focus any time I trained my lower body? Adding weight to my squat or deadlift.

I was able to add a bit of weight to the bar over time, sure. But I couldn't even feel the muscles of my lower body working when I lifted. Every rep just felt like a dull pain in my joints and ligaments. My body felt tired and achy - my glutes, hamstrings, and quads felt nothing.

My reps got sloppier and sloppier, but I powered forward.

"I have to keep pushing the weight if I wanna grow!"

Like usual, I continued to push this for a stupidly long time.

Finally (after literal years), I couldn't take the achy joints and lack of progress anymore.

I decided it was time to take my ego out of the equation and quit focusing so much on the amount of weight I was lifting.

My new focus?

Being crazy intentional with my lifting. I wanted to be capable of owning every inch of the movement with extreme control. I wanted to be able to accelerate the bar faster, and feel the desired muscles working. When coaching online clients through this process now, I call this "focusing on rep quality".

Here's the thing - building muscle is all about creating tension.

Two different types of tension, in fact:

1. Intramuscular tension: Intramuscular tension is created and increased by adding weight to the bar, lifting the same weight faster, lowering the same weight slower, or a combination of the three.

2. Time Under Tension: This is the amount of time your muscles are under strain during a set/session.

To build muscle, you need adequate amounts of both types of tension. 

I had been creating lots of intramuscular tension by focusing so much on weight, but I wasn’t creating enough time under tension for the specific muscles I wanted to grow. The poor rep quality meant the tension that should have been distributed to my glutes, hamstrings, and quads, was instead put on the surrounding joints, ligaments, and tendons.

This is a concept I walk most every online client through in the first few months of their training program. People are typically focused ONLY on either:

a.) Feeling the muscle work

b.) Increasing weight.

To create adequate time under tension in the muscles you WANT to build, your rep quality must be high - you need to be able to control the rep and feel the muscle work.

To create adequate intramuscular tension, you need to push the weight.

The mind-muscle connection and weight BOTH matter... don't get too caught up in just one.

2. You're NOT Using Machines

The machine are isn't just for old dudes who are insanely comfortable with their locker room nakedness.

There's a place for machine work in your training program as well.

You'll hear a lot of people say...

“You only need to do squat, bench, deadlift, and chin-ups to build muscle. Don’t waste your time with isolation work and machines.”

I was that guy for a long time.

Back then, the idea of swapping a barbell back squat for a leg press would have been blasphemy - like saying Katy Perry makes better music than Taylor Swift. Pure blasphemy.

The mindset shift came at the same time as what I discussed in mistake #1 - when I realized how important being able to feel a muscle work is for generating tension in said muscle.

Here’s how I see things now:

→ In defense of compound barbell/dumbbell movements: These are great for training lots of muscle groups at once - you get lots of bang for your buck. In terms of creating growth stimulus for multiple muscle groups as efficiently as possible, these rule.

Plus, these movements have MUCH more carryover to real life and functional strength, as you’re NOT working in a fixed path, and are forced to recruit many more stabilizing muscle groups. It would be ridiculous (for most people) to NOT include these in their training. Yes, even you naked old guys in the locker room.

→ In defense of machines: The fact that you’re not training tons of different muscle groups at once allows you to focus on creating tons of tension in the specific muscle group you want to focus on.

Anecdotally from my work with clients and my own training, this is especially invaluable when it comes to lower body training.

Movements like squats and deadlifts are GREAT, and should be the foundation of your training, don’t get me wrong.

The problem is, the limiting factor (the “weak link” that causes you to have to end the set) often ISN’T your lower body - it’s your core stability.

Machines are great for building your lower body, because they essentially take the stability component out of the lift, and allow you to be very intentional about creating tons of tension in the desired muscle group.

They also allows you to more effectively target specific weak points (e.g. the ability to work the hamstrings in isolation.)

If your goals are to get stronger and build muscle - it makes sense to train both the compound barbell movements AND incorporate machine work.

Although I build online clients training programs very specific to their needs, I would guess I generally program about 70% barbell and dumbbell work, 30% machine work.

3. You're Not Doing Core Stability Work

Another huge problem that held my progress back for years was back pain.

Every time I would push my lower body training - or even do a bent over movement - I would get shooting pain in my lower back, and have to lay off anything that stressed my back for the next few weeks.

Obviously, this was hindering my progress.

I refused to believe a weak core could be the issue.

“I do hanging leg raises all the time. My abs feel thick. I DON’T have a weak core.”

This is the most common confusion I see when it comes to core training. People spend A LOT of time training the rectus abdominis (what you think of as your "ab muscles"), which is basically training the ability to flex your spine.

The problem is, very little time is spent training your core to be better able to resist movement (which is exactly what you NEED it to be able to do to stay pain-free on movements like squats or deadlifts.)

As a result, people can train their abs a lot (e.g. me)… and still have a very weak core and back pain.

50%+ of the new online clients I onboard report back pain. It's almost always gone within the first month of following a well-designed training program that gets the focusing on core stability and fixing any other imbalances.

On a similar note, you’ll hear a lot of people say...

“All you need to do is squat and deadlift. Your core will get plenty strong.”

From my experience with hundreds of online and in-person clients, that’s almost never the case.

Anti-movement work helps a TON.

This is exactly why I always program at least 2-3 anti-movement exercises into my online client’s training programs. 

I went pretty in-depth on this in “The Movement Hierarchy”, but here’s a basic structure of how to effectively train your core:


→ You can train anti-movement a lot without any recovery issues. Try to work at least one of each of the following categories into your program weekly. 3-4 sets of each. 8-10 reps OR 30-45 seconds of work.

 Anti-Extension - The goal here is to resist extension at the spine. A few options:

  • Ab Wheel
  • TRX Fallout
  • Renegade Row
  • Hollow Body Sweep
  • Hollow Body Flutter Kick
  • Hollow Body Pull-Apart

Anti-Rotation - The goal here is to resist rotation at the spine. A few options:

  • Pallof Presses/Holds
  • Renegade Rows
  • Swiss Ball Stir-The-Pot
  • Birddog Row

Anti-lateral flexion - The goal here is to resist sideways bending at the spine. A few options:

  • KB Bottoms Up + Farmers Walk
  • Chaos Farmer’s Walk
  • Suitcase Carries
  • Farmer Carries

4. You're Doing Too Much Mobility Work

You DON’T need to do 30-minutes of mobility every day. 

Ever wonder why you can drop into a deep body weight squat... but once you apply a somewhat difficult load, you can barely hit depth?

In this situation, the common thinking is...

"I must need to do more mobility work!"

Buuuut, you just did an ass-to-grass body weight squat... so we know you have the prerequisite mobility.

So, what's really going on here?

Somewhere in the chain of muscles and joints between the barbell on your back and your feet planted on the floor, your brain sense that something in the chain isn't stable enough to safely squat this load to the full potential of your mobility.

Your central nervous system basically "puts the brakes on", and prevents you from squatting deeper.

This feels like a lack of mobility, but really...

A lack of stability often masks itself as a lack of mobility.

A groundbreaking concept that helped me understand this (and stop being mobility guy) was understanding the Mobility - Stability Continuum.

Your body’s major joints essentially live in a co-dependent relationship, critical to you feeling good and moving well.

Basically, you have mobile joints and stable joints.⠀

Mobile joints have a wide range of motion, allowing for lots of movement.

Stable joints resist undesired movement.

The dope thing is - your major joints alternate in what they need - more mobility or more stability.

A joint that needs more stability has joints on either side that need mobility, and vice-versa.

→If one of these joints is lacking adequate mobility/stability, a domino effect is created. This can surface as issues at OTHER joints, that at first glance aren’t related to the real source of the problem.

→ When there’s an issue with mobility/stability in one joint, the body shifts the movement or stability demands to the above and below joints - which aren’t designed to be mobile/stable.

This typically manifests itself as pain in the joint above or below the actual source of the problem.

Example 1: One of the most common areas I see this in - poor scapular stability manifesting itself as shoulder pain. Often the solution isn’t doing more shoulder mobility work, it’s working on stabilizing the scapula.

Example 2: Say you can’t get much movement out of your hips. So, the needed movement shifts to your knees and lumbar spine. This results in your back rounding forward as you squat. But the issue here isn’t (at least entirely) lumbar spine stability, it’s hip mobility.

Basically - if you’re having pain/mobility issues with a joint, the solution might NOT be implementing joint specific mobility work, but looking to the joints above and below.

5. You're Not Doing Cardio

Really. Let me explain.

Your energy for different activities in the gym comes from three main energy systems:

1. Anaerobic-Alactic System - Primarily fuels the first ~15 seconds of exercise

2. Anaerobic-Alactic System - Primarily fuels the first ~60 seconds of exercise

3. Aerobic System - Primarily fuels from 60-90 seconds on exercise forward

Now, when you're lifting weights, you're primarily using the first two "anaerobic" energy systems.

You're probably NOT doing much training to build your aerobic system - hundreds of people have to you that "steady state cardio kills your gains".

The reality is - cardio doesn't steal your gains, it helps them.

Not to sound all scienc-y, but...

Your aerobic system drives restoration of homeostasis within the cellular environment following anaerobic energy production.

Basically, your aerobic system is what helps you recover from anaerobic efforts (lifting).

A higher level of aerobic fitness (to an extent) will translate to faster recovery and likely heavier weight lifted (due to decreased fatigue) between sets.

Secondly, you need to consider your autonomic nervous system (ANS).

Your ANS handles the processes in your body that don't require conscious control. Things like breathing, blood flow, digestion, etc.

The ANS has two main branches:

1. The Sympathetic Nervous System (SNS) a.k.a. Fight or Flight Mode

2. The Parasympathetic Nervous System (PNS) a.k.a Rest and Digest Mode

The ANS is always activated, and is in either a sympathetic or parasympathetic state.

When you're in a sympathetic state - You’re in “fight-or-flight mode”. You’re sensing some eminent danger or threat. To get ready to fight, better perform in the gym, or even run away, adrenaline and cortisol are released, and blood flow to the major muscle groups increases. Your body shuts down or slows many processes you don’t need to survive in the short-term (digestion, hormone production, etc.)⠀This is rarely caused by actual physical danger. Most any stressful situation, physically or mentally, puts you in a sympathetic state.

The sympathetic state is catabolic. It breaks things down. Sympathetic states are often activated through:

→ Intense workouts

→ Stress in daily life

→ Too little sleep

→ Stimulants

→ Under-eating⠀

^All necessary at certain times to achieve your goals. Stress/sympathetic states aren't bad - just be sure to take time to recover from 'em.⠀

When you're in a parasympathetic state - Your body is in “rest and digest” mode. This is where the important factors to recovery happen. Your body is producing hormones, digesting food, absorbing nutrients, building muscle, etc.

The parasympathetic state is anabolic. It builds. So obviously, outside of the necessary sympathetic state required to stimulate muscle growth in the gym, we WANT to spend as much time in a parasympathetic state as possible.

Outside of managing life stressors properly, one of the best things you can do to spend more time in a sympathetic state is... you guessed it...


As the aerobic system develops, the PNS response increases. Having higher aerobic fitness allows you to get back into a parasympathetic state quicker after training - translating to more gains.

For more on programming cardio specific to your goals, go HERE.

Time to stop making these mistakes - I promise you, the results will come MUCH quicker.

About The Author

Jeremiah Bair is the biggest Taylor Swift fan in Lincoln, NE. He's also a certified nutrition coach, strength coach, and owner of the Online Coaching Business Bairfit. His Instagram is noticeably missing any calf pictures.

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