Bench Press: is it a dangerous workout exercise?

Bench pressing is more likely to cause an injury and keep you out of the gym

benchpressThe flat bench press is one of the most popular chest-strengthening exercises in the gym. But according to Ulrik Larsen, this staple of gym training needs to be modified to prevent the risk of shoulder injury

Among those who keep up with sports science research, the standard flat bench press (FBP) is fast becoming the black sheep of gym exercises – and for good reason: it is widely reported as being the most common cause of shoulder injuries in the gym. Yet despite the growing recognition of this risk, the flat bench press remains very popular with personal trainers and strength and conditioning coaches. It is time for a serious reappraisal.
There is no doubt that the flat bench press is an extremely good way to grow a big chest – hence its abiding popularity among certain gym-goers! (This also has a lot to do with the extra levels of effort generated and hormone production that occurs when a 100kg weight is precariously balanced above your neck... there is nothing like a little fear to boost a person’s motivation!)

The same levels of pectoral growth cannot be achieved with standing cable presses, or single arm dumbbell presses on swiss balls, even though biomechanically they are profoundly safer, as they spread the load across numerous body parts. So, rather than try to outlaw an exercise that is likely to remain extremely popular because it delivers what so many people want in the gym, let us look at how to overcome its dangers with some intelligent modification.

What’s the problem?

1. The bench

The high levels of injury associated with the FBP are primarily caused by the bench itself. It is relatively common to find that someone will experience shoulder pain with the FBP, but none if they are doing normal prone push-ups. This is because the effect of most benches is to severely restrict the movement of the scapulae (shoulder blades), thereby artificially exaggerating the movement of the glenohumeral (main shoulder) joint (see figure 1 for an illustration of the key muscles under discussion in this respect). It is possible to find very narrow benches, but there is a real risk of falling off sideways during the exercise, especially when fatigue sets in! And although a unique type of bench does exist that has notches cut out of it to allow the scapulae to retract, it is rare to see one in the gym.

Figure 1

2. The scapula is blocked

As the bench restricts the movement of the scapula, at the shoulder joint the ‘ball’ is forced to move to the end of its range in the ‘socket’. The scapula is unable to retract on the latter part of the down phase, as the elbow moves past the point of the shoulder (the humerus is horizontally hyper-extending); and is unable to protract with the latter part of the up-phase as the elbow moves to the ceiling (the humerus is horizontally hyper-flexing, see figure 2).
Ideal movement of the scapula is primarily achieved by the underrated serratus anterior muscle working concentrically on the push phase to produce protraction, and eccentrically on the return phase to produce controlled retraction. Excellent drills have been developed and are available these days for the training and activation of this key shoulder stabilising muscle.

So, in the FBP, instead of the scapula and humerus moving synergistically (together), a kind of ‘lurching’ takes place, in which the point of the shoulder flicks in the opposite direction to the point of the elbow. This is catastrophic for all the fragile structures in the shoulder joint.

Figure 2

3. Excessive humeral head movement

The effect of the repeated lurching movement at the humeral head is to overload the external rotators of the rotator cuff (infraspinatus and teres minor), causing them gradually to become tighter and tighter in response. The first sign of this is the reduced ability of someone to reach up behind their back, as if to do up a bra or scratch their back – this indicates a decrease in internal rotation flexibility as the external rotators become too tight.
The internal rotator cuff muscle (subscapularis), in contrast, becomes gradually biomechanically disadvantaged, inhibited and weakened. This imbalance between external and internal rotators in the injured shoulder, resulting in inhibition of the subscapularis, is well supported in the research literature (see ‘Further reading’ box, below right).
Crucially, at the bottom of the press movement, where the head of humerus lurches forward, the subscapularis tendon (as it rises from the armpit at the front of the shoulder) is unable to exert its counter-balancing, stabilising force. The scapula must retract sufficiently at this point to give the tendon better traction to prevent the destructive anterior shear of the humeral head. Studies of electrical activity in subscapularis muscle have discovered that the motor nerves supplying it are separated into upper and lower portions, with the upper portions of the muscle more active in abducted positions, and the lower portions more active in lower degrees of abduction movements.

4. The bar

A related, if less severe, biomechanical challenge with FBP is the use of the weighted bar. There is good reason to believe that the restricted capacity for supination and pronation of the wrist/elbow joint complex during the exercise leads to altered muscle recruitment patterns around the shoulder complex.

Take, for example, the top of the press movement. A ‘free’ dumbbell-weighted hand that is able to move as it wants to in space will ideally subtly supinate to enhance external rotation of the glenohumeral joint and scapular protraction. With the bar, the forearm is kept in relative pronation and the humerus is forced into internal rotation, increasing the risk of subacromial impingement.

Poor biomechanics, poor results

The progressive tightness at the back of the shoulder socket leads to the head of humerus being nudged anteriorly and superiorly (forwards and up) into the socket during the press movement. This frontal shear creates overload of the long head of biceps tendon as it crosses the front of the shoulder, and the upwards shear creates compression of the supraspinatus tendon under the acromion. Compression and shear forces gradually worsen and pain, inevitably, results.
Typically the top, side or frontal aspects of the shoulder will begin to ache after training or the next day, perhaps during warm-up, under heavy loads or with fatigue. The pain may emanate from inflamed tendon structures or from the labrum (cartilaginous rim of the socket) or subacromial bursa or up-regulated neural structures. In the end, the precise diagnosis matters less than understanding  the mechanism that has caused the pain.

Alongside pain, muscular development in the chest will be inhibited and distorted. The pectoralis minor will begin to dominate the press movement, preventing the pectoralis major from developing as it should. The glenohumeral lurching will ensure that the pec major does not have a strong base from which to operate, again preventing its normal development. Instead the shoulders just become rounded, possibly with a tendency to develop the anterior deltoids and triceps over pec major.

In summary, the most common cause of rotator cuff injuries in the gym is excessive and uncontrolled glenohumeral movement, because of insufficient scapular movement and control.

Put another way, good push-pull biomechanical technique always requires sufficient movement of the scapula with the humerus. This notion may well be at odds with some schools of thought among trainers and strength coaches, where the emphasis is on ‘locking back’ the scapula at all times, as a sign of good scapular control. While there may be an argument for this early in the training regime of those with very poor muscular development and body awareness, all the research and anecdotal evidence strongly suggests that the scapulae should not be locked if one wants to protect the fragile structures of the glenohumeral joint and develop the muscles of the shoulder optimally.
In my opinion every strength coach and trainer should know how to activate or enhance the protraction and retraction movements of the scapula, in order to prevent rotator cuff overload and shoulder pain.

How to modify the bench press

The following two approaches will allow you to start the process of correcting bad mechanics and enforcing good movement patterns without the need to ban the bench press from your exercise repertoire. The first physically alters the bench to give you a chance to use your scapula, the second gives movement feedback to challenge you to isolate and activate key muscles.

Pool noodle

Pool noodles are standard easy-to-buy long cylindrical foam floats, widely used in aqua aerobics classes. You will need one that is 100mm or less in diameter and ideally with some ‘give’ in it. A half-circular foam roller will do the same job; a full one is too high. The noodle needs to run the length of the spine, so that head to pelvis can lie on it during the exercise (see figure 3). If the noodle sits too high off the bench, it makes it too unstable to perform the exercise safely; if it is too soft (eg, a hollow-core pool noodle) it will not act as a stimulus to change the movement of the scapula.

Figure 3

Lie supine, as normal, with the noodle placed longitudinally under the length of the spine (including the head) on the bench. Perform a set or two using just the bar to get used to the feel of it. Then gradually add weight, taking care not to allow the bar to fall sideways.

During this simple modification of the bench press, the scapulae will be able to protract and retract. Mental cues such as: ‘Open your chest’ as the elbow travels beneath the level of the bench can be excellent. As the scapulae retract to their limit, the elbows should not descend any further, thus preventing even the slightest lurching.

On the latter part of the push-up phase, you can bring your scapulae somewhat further around the rib cage (protraction), but care must be taken to not allow shrugging of the shoulders (over-activity of upper trapezius and levator scapulae) or flexion of the trunk. Pure protraction of the scapulae without downward rotation is invaluable for good serratus anterior development, and minimises dominance of pec minor over the pec major muscles.

Rubber tubing

Acquire some low-resistance therapeutic rubber tubing (be sure to use the round hollow core tubing, not stretchy elastic bands sheets – for this purpose they are no good). Make a loop at either end so that you can hold on.
Start by performing the bench press (with the pool noodle ideally), using a low weight on the bar. Hold on to each end of the tubing at the loop handles, or alternatively fix the ends of the tubing to the ends of the bar outside the weight plates (see figure 3). Have a friend or trainer who can position themselves at the head-end, holding the middle of the tubing .

As you perform your bench press, ask your trainer to gradually increase the pulling force on the tubing, creating additional torque (rotary force) around the shoulder. Be careful that your alignment remains constant (the forearms should remain vertical). It should be easy for you to resist the force and continue their bench press.

The pulling force of the tubing is towards external rotation of the glenohumeral joint, so as you resist, you have to activate your internal rotators. And because you are resisting a static force, you are more likely to recruit the deep internal-rotation stabiliser subscapularis in preference to the ‘mover’ muscles such as teres major and latissimus dorsi. This extra level of activation of subscapularis braces the anterior aspect of the glenohumeral joint, preventing it from lurching forward and upwards in the socket.

In my experience, this activation mechanism is frequently extremely effective in removing pain from pressing movements. Many shoulders will feel ‘different’ in a way that equates to feeling more ‘safe’ and ‘strong’ in the shoulder when it is under load.

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