Thick-bar or fat-grip training for grip hypertrophy

Increasing the bar diameter forces the forearm flexors to work harder for the same external load.

Why it works

Standard bar diameter (28 mm) allows the fingers to overlap comfortably, reducing the mechanical demand on the forearm flexors. Fat grips or thick bars (50+ mm) prevent this overlap, requiring more motor unit recruitment in the flexor digitorum and extensor muscles to maintain the grip. The increased neural demand and mechanical tension drive forearm hypertrophy and grip strength gains at loads that would be submaximal on a standard bar.

How to do it

1. Purchase fat grip adapters (e.g., Fat Gripz) and slide them onto barbells or dumbbell handles for rows, curls, and pulls.
2. Start with the same exercise at 10–20 % less load to account for the reduced grip security.
3. Focus on exercises where grip is already the weak link (rows, pull-ups, deadlifts).
4. Use fat grips for 1–2 exercises per session, not every movement.

Evidence

Thick-bar training increases forearm muscle activity (EMG) and produces greater grip strength gains than standard bar training in several small studies; used extensively in strongman and arm wrestling training based on practitioner evidence. Krings et al. (2021) measured the effect of fat grip attachments on muscular strength and neuromuscular activation during resistance exercise directly. (observational)

Most supporting studies are small and short. Fat grips require careful load management to prevent loss of control during pulling movements.

Sources

• Krings BM, Shepherd BD, Swain JC, Turner AJ, Chander H, Waldman HS, McAllister MJ, Knight AC, Smith JW. (2021). "Impact of Fat Grip Attachments on Muscular Strength and Neuromuscular Activation During Resistance Exercise." Journal of Strength and Conditioning Research, 35(2S):S152–S157.

Common mistake

Using fat grips on every exercise, which reduces the total load you can move across the session and limits the stimulus to other muscle groups.