Equipment guides often say that a cable stack should be used overhead for triceps, or that an incline bench or a preacher bench suits curls better, because the position changes how stretched the muscle is. This article summarises the abstracts of three training studies that tested that idea: a 12-week trial of cable triceps extensions in the overhead and neutral arm positions, a 12-week trial of incline against preacher dumbbell curls, and a 9-week trial of the same two curls in women. Two of the three come from the same research group, and all are small. This site’s guide to stretch-mediated hypertrophy reviews the wider idea, and the guide to arm training equipment covers the kit.
Triceps: overhead against neutral arm position (2023)
Maeo and colleagues, in the European Journal of Sport Science in 2023, had 21 adults train one arm in the overhead position and the other in the neutral position on a cable machine. Both arms did elbow extensions at 70% of their one-repetition maximum (1RM), 10 repetitions for 5 sets, twice a week for 12 weeks. Loads were raised by 5% of 1RM per session when the previous session was completed without repetition failure, and they rose similarly in both arms, but the weights used were always 34 to 39% lower in the overhead arm. Muscle volume was measured by MRI. The change in the long head of the triceps, which crosses the shoulder as well as the elbow, was 1.5-fold greater in the overhead arm (+28.5% against +19.6%). The side heads grew 1.4-fold more (+14.6% against +10.5%) and the whole triceps +19.9% against +13.9%. The authors concluded that overhead cable extension should be favoured if the aim is to maximise triceps growth, even though lower loads were used.
Training each arm differently within the same person controls for differences between individuals, which strengthens the comparison, though 21 adults is a small sample.
Biceps: incline against preacher dumbbell curls (2026)
Kobayashi and colleagues, in the Journal of Sports Sciences in 2026, had 21 untrained adults train one arm with incline (shoulder-extended) curls and the other with preacher (shoulder-flexed) curls for 12 weeks, twice a week. Magnetic resonance imaging measured the volume of the biceps brachii, brachialis and brachioradialis, three elbow flexor muscles. The biceps brachii grew more after incline curls (+22.1% against +18.9%), while the brachialis (+17.1% against +21.1%) and brachioradialis (+13.5% against +17.6%), two other elbow flexor muscles, grew more after preacher curls. Total elbow flexor growth did not differ (+17.6% against +19.2%). The authors described small to moderate exercise-specific differences and limited influence of exercise configuration on total growth.
Biceps: incline against preacher curls in women (2023)
Zabaleta-Korta and colleagues, in the Journal of Human Kinetics in 2023, assigned 38 healthy women to nine weeks of incline curls or preacher curls (four sets of 12 repetitions to failure, three times a week). Muscle thickness was measured by ultrasound at three sites along the upper arm. No region of the incline group grew significantly from before to after training. At the site nearest the elbow, the preacher group grew significantly (about 2.70 to 2.94 cm). There were no significant growth differences between regions, groups or group-by-region. The authors interpreted this as the preacher curl placing the most strain where the arm muscles are more elongated, and the study did not find growth differences between the groups across regions.
What the three studies suggest
- The triceps study gave the clearest result: overhead cable extension produced more growth than the neutral position, using lighter weights.
- The two biceps studies point in different directions. The 2026 trial found little difference in total growth, with the incline curl favouring the biceps itself and the preacher curl two neighbouring muscles. The 2023 trial in women found growth only in the preacher group at one site.
- The curl studies enrolled untrained or recreationally trained participants and all three trials ran 9 to 12 weeks, so they say little about experienced lifters or longer periods.
- Equipment matters mainly for access: overhead triceps work needs a cable stack at a suitable height, and the curl comparison needs an adjustable bench or a preacher pad.
FAQs
Should triceps extensions be done overhead?
In the 2023 trial of 21 adults, overhead cable extension produced greater triceps growth than the neutral position over 12 weeks, even with lower loads. It is one trial, so it is a reason to favour the position, not proof for every lifter.
Is the preacher curl better than the incline curl?
The two studies disagree. One found little difference in total growth, and in the women’s trial muscle thickness increased significantly at one site in the preacher group and at none in the incline group.
The bottom line
Training in a position that stretches a muscle more gave clearer benefits for the triceps than for the biceps in these three small studies. The overhead cable extension grew more triceps volume than the neutral position over 12 weeks using lighter weights. Incline and preacher curls gave mixed and smaller differences, with total elbow flexor growth similar in the 2026 trial. A cable stack and an adjustable bench cover both positions, but the evidence does not show that one curl setup is clearly superior.
Sources
- Triceps brachii hypertrophy is substantially greater after elbow extension training performed in the overhead versus neutral arm position, European Journal of Sport Science, 2023 (pubmed.ncbi.nlm.nih.gov)
- Exercise-specific preferential hypertrophy of individual elbow flexor muscles after incline versus preacher dumbbell curl training, Journal of Sports Sciences, 2026 (pubmed.ncbi.nlm.nih.gov)
- Regional Hypertrophy: The Effect of Exercises at Long and Short Muscle Lengths in Recreationally Trained Women, Journal of Human Kinetics, 2023 (pubmed.ncbi.nlm.nih.gov)