To activate your muscles to the max adjust your incline to 30 or 45 degrees the next time you bench press, say exercise scientists.

Carried out using free weight barbells, their small study questions the traditional, horizontal position many still use for the bench press.

The team from the Univesity of Toledo recruited 14 healthy men whose average age was 21, all of which had more than a year's worth of experience in strength training.

They averaged 8.7 per cent body fat, making them a lean, fit group, and participants set their own intensity levels.

Two sessions were held within 48 hours of each other and for each one, participants were asked to refrain from upper body strength training for 48 hours before starting and also to avoid strenuous exercise for 24 hours beforehand.

After a five-minute warm-up on a stationary bicycle, participants performed a set of 10 reps, followed by a set of six reps of barbell bench press on a horizontal angle.

Next, researchers worked with participants to determine each one's maximum bench at a horizontal angle.

After a recovery break, participants with performed six reps of the bench press at angles of 0, 30, 45 and -15 degrees to familiarize them for the next session.

In the second session, researchers attached the young men to electrodes to assess their contractions.

After they warmed up, participants were asked to contract each of the target muscles to the max for five seconds in order to normalize the data picked up by the electrodes.

Next, they performed one set of six reps at each of the four aforementioned angles using barbells that weighed 65 per cent of their maximum bench.

Targeting the upper and lower pectoralis major, anterior deltoid and lateral triceps brachii, the researchers' observations led them to conclude that an incline of 30 or 45 degrees is optimal.

"The results suggest that an incline bench angle of 30° is more beneficial than 45° as it resulted in the same upper pectoralis activation but 30° resulted in great lower pectoralis activation," write the researchers.

As for performing the bench press on the horizontal, it's still an effective move, say the researchers, but it activates fewer muscles than the angles of 30 and 45 degrees.

The study was published in the European Journal of Sport Science.