Thick-handled bars and rubber “fat grip” sleeves that clip onto a standard barbell or dumbbell are sold as a way to build a stronger grip and harder-working arms. This article summarises the abstracts of three small studies: an acute study of two bar diameters, an acute study of a fat grip attachment across several lifts, and an eight-week training study in golfers. The standard Olympic bar in the first study was 28 mm (1.1 inches) thick, and this site’s guide to barbell specifications covers bar dimensions. None of the three studies are large enough to settle the question.
Study one: 28 mm bar against 51 mm bar
Fioranelli and Lee, in the Journal of Strength and Conditioning Research in 2008, compared a standard Olympic bar (28 mm, called THIN) with a larger fat bar (51 mm, or 2 inches, called THICK). Eighteen healthy men performed a unilateral isometric bench press, pushing against a fixed position, with each bar at two elbow angles, about 45 and 90 degrees. They also held 80% of maximum effort for 10 seconds while electromyography recorded the activity of the pectoralis major (chest) and the forearm flexors.
Maximum voluntary contraction did not differ between bars, although it was greater at the second joint angle. Muscle activity in the forearm muscles at both angles, and in the pectoralis at the first angle, was greater with the thin bar. The authors concluded that their data did not support the idea that bar diameter influences performance in an isometric bench press, and that the higher activity with the thin bar suggested greater neuromuscular activation with a standard Olympic bar than with a fat bar. They added that the findings should be confirmed in other resistance exercises.
Study two: fat grip attachments across five exercises
Krings and colleagues, in the same journal in 2021, tested Fat Gripz attachments on 15 resistance-trained men, in a randomised comparison against an ordinary Olympic barbell. The men found their one-repetition maximum (1RM) for the deadlift, bent-over row, upright row and concentration curl, and completed as many pull-ups as they could, with and without the attachments. Electromyography measured eight upper-limb muscles.
- With the attachments, 1RM strength fell significantly in each exercise, and the maximum number of pull-ups was significantly lower.
- Muscle activity rose significantly in the forearm and shoulder muscles but fell significantly in the upper arm muscles during the deadlift, bent-over row and pull-ups.
- There was no difference in muscle activity for the upright row or the concentration curl.
The authors suggested that the differences may relate to the muscle length positions involved. They concluded that although fat grips may increase neuromuscular activation, the loss of strength may lead to lighter training loads that may not be ideal for building muscular strength.
Study three: eight weeks of fat grip training in golfers
Cummings and colleagues, in the same journal in 2018, noted that earlier research on fat grips was mostly acute. They randomly assigned 10 Division I male golfers to two groups of five: one performed every lift and repetition with fat grips and the other used normal-diameter bars. Both followed an eight-week periodised resistance programme three days a week. Outcomes included swing speed, ball speed, driving distance and carry, maximum pull-ups, grip strength in each hand and 1RM trap-bar deadlift.
The fat grip group showed significant increases in ball speed, carry, drive distance and left-hand grip strength. The authors concluded that in a population such as low-handicap collegiate golfers, fat grip training may help golf-specific performance after eight weeks of periodised training, and that coaches may use it with athletes who need adequate grip strength.
What the three studies show together
- In two acute studies, the thicker grip did not raise strength, and in the second it lowered maximal strength in every exercise tested.
- Muscle activity was not uniformly higher: it depended on the muscle, the exercise and the study, with the forearms and shoulders more active in one study and the thin bar giving more activity in another.
- The only training study found gains in a sport-specific outcome and one measure of grip strength, but it involved five golfers per group.
What the studies cannot show
The samples were small: 18 men, 15 men and 10 golfers. All participants were men, and the third study involved a specialised group of athletes. The training study measured golf performance and grip strength, not general strength or muscle growth, so it cannot show how fat grips affect gym progress in the general population. The second study found that thick grips reduced the load that could be lifted, which the authors linked to lighter training loads. This site’s guide to grip strength training equipment covers other ways to train the grip.
What this means when buying equipment
A fat grip attachment is a cheap accessory, but the evidence supports it as a grip-focused tool, not as a general strength or muscle-building upgrade. The first two studies found no strength advantage from a thicker grip, and in one study strength was lower. Buyers who want a specific grip challenge could try attachments on lighter loads, while others may get more from the standard bar or from other grip work.
Frequently asked questions
Do fat grips make the arms work harder?
Not consistently. In the 2021 study they increased forearm and shoulder activity but reduced upper-arm activity in some lifts, and in the 2008 study the thin bar produced greater forearm and chest activity.
Do fat grips reduce the weight a person can lift?
In the 2021 study, one-repetition maximum was significantly lower in every exercise tested when the attachments were used.
The bottom line
Three small studies found that thicker grips did not increase strength and lowered it in the largest acute test, that muscle activity changed in ways that varied by muscle and exercise, and that eight weeks of fat grip training improved some golf and grip measures in five golfers. Fat grips are best treated as a specialised grip tool rather than a general upgrade.
Sources
- Fioranelli D, Lee CM, “The influence of bar diameter on neuromuscular strength and activation: inferences from an isometric unilateral bench press,” J Strength Cond Res, 2008
- Krings BM, Shepherd BD, Swain JC, et al., “Impact of Fat Grip Attachments on Muscular Strength and Neuromuscular Activation During Resistance Exercise,” J Strength Cond Res, 2021
- Cummings PM, Waldman HS, Krings BM, Smith JW, McAllister MJ, “Effects of Fat Grip Training on Muscular Strength and Driving Performance in Division I Male Golfers,” J Strength Cond Res, 2018