How your nervous system makes you stronger, at every stage of lifting

Most people assume bigger muscles are the whole story behind bigger lifts. Muscle matters, but there's another part that gets far less credit: your nervous system. It keeps improving how you lift whether you've been training for three months or ten years.

What a neurological adaptation is

Your brain and spinal cord tell your muscles what to do. Every time you lift, they send signals that switch on muscle fibres. The better those signals get, the more force you can produce, and that can happen before you've added any new muscle at all.

That's why new lifters get stronger so quickly even though they don't look much different yet. And those changes don't stop after year one. They keep going in experienced lifters too, just more slowly.

What changes, and when

Beginners (0 to 12 months of training)

In your first year, your nervous system is learning how to use the muscle you already have. Most of the early progress comes from four things:

• Better motor unit recruitment. You switch on more muscle fibres for the same lift.
• Faster firing (rate coding). Muscles contract harder and faster.
• Better coordination. The movement patterns for the big lifts get cleaner.
• Less "braking" from opposing muscles. The muscles on the other side of the joint (your hamstrings in a squat, for example) learn to relax instead of fighting you.

Intermediate and advanced lifters (1 to 5+ years of training)

After the first year or so, muscle growth takes over as the bigger driver of strength. Your nervous system still keeps adapting, though:

• Better motor unit synchronization. Fibres may fire together in a more coordinated way, though the research hasn't clearly shown this one yet (Gabriel et al., 2006).
• More power. This is a big deal for max effort lifts.
• Cleaner movement patterns. Less wasted energy and better technique.
• Advanced rate coding. You can hold high force for longer.

What the studies say

Researchers don't fully agree on whether neural adaptations keep going past the beginner phase. Here's what a few of the well known studies found.

Studies that point to neural gains beyond the beginner stage

• Häkkinen et al. (1985) put men who already lifted through 24 weeks of heavy training. Their strength went up 27%, and the gains tracked increases in neural activation during the hardest training months. Their muscle fibres grew in the first 12 weeks and then stopped growing.
• Sale (1988) reviewed the evidence that training teaches your nervous system to switch on the main muscles more fully and coordinate them better, and looked at how much neural and muscle changes each matter in short term and long term training.

Studies that say it's mostly a beginner effect

• Moritani & DeVries (1979) found that in an 8 week program, neural changes explained most of the early strength gains, and muscle growth became the bigger factor after the first 3 to 5 weeks.
• Enoka (1988) argued that strength depends heavily on the nervous system, but most of the evidence he reviewed for neural gains came from short term training.
• Gabriel et al. (2006) reviewed the research and found the clearest signs of neural change early in training, such as stronger signals from the brain and changes in how motor units fire.

How to train your nervous system

Wherever you are in your training, these are the habits that get the most out of your nervous system:

• Lift with intent. Try to move the bar as fast as you can, even when it's heavy and it isn't moving fast at all. The effort itself improves motor unit recruitment.
• Train explosively. Plyometrics, Olympic lifts and speed work sharpen rate coding.
• Clean up your technique. The better your form, the more efficiently your nervous system can do its job.
• Lift heavy for low reps. Working at 85 to 100% of your 1RM strengthens the neural pathways for that lift.
• Rotate in new lifts and variations. Unfamiliar movements make your nervous system adapt again.

Where muscle fits in

Muscle size still matters, and after the first year it does more of the heavy lifting, so to speak. But your nervous system decides how much of that muscle you can actually use. That's true when you're chasing your first squat PR, and it's still true years later when you're stuck on a plateau.

References

1. Moritani T, deVries HA (1979). Neural factors versus hypertrophy in the time course of muscle strength gain. American Journal of Physical Medicine, 58(3):115-30. PubMed
2. Häkkinen K, Alén M, Komi PV (1985). Changes in isometric force- and relaxation-time, electromyographic and muscle fibre characteristics of human skeletal muscle during strength training and detraining. Acta Physiologica Scandinavica, 125(4):573-85. PubMed
3. Sale DG (1988). Neural adaptation to resistance training. Medicine and Science in Sports and Exercise, 20(5 Suppl):S135-45. PubMed
4. Enoka RM (1988). Muscle strength and its development. New perspectives. Sports Medicine, 6(3):146-68. PubMed
5. Gabriel DA, Kamen G, Frost G (2006). Neural adaptations to resistive exercise: mechanisms and recommendations for training practices. Sports Medicine, 36(2):133-49. PubMed

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