Chest Training

It seems like the most pertinent of muscles to train. We hope it enters the room a moment or two before the rest of our body follows and it seems to be the standard most people are measured by with regard to any training talk; “How much do you bench?”

Let’s first consider the muscle that the chest is composed of; the pectoralis major and pectoralis minor. Biomechanically the pec major serves to adduct the humerus (upper arm) back towards the mid-line of the body; originating on the inner edge of the front of the clavicle and the cartilages of the 2nd to 6th ribs at the sternum, and inserting on the outer edge of the bicepital groove on the humerus. The pec minor originates on the upper edge of the 3rd, 4th and 5th ribs and inserts on to the caracoid process of the scapula.

Whilst you might be wondering the purpose of this anatomy lesson, it is important to consider the way a muscle is designed to move and where it pulls against when it contracts to better understand how to train the muscle. If we reflect on exercise to train the pectorals we might consider the likes of bench press, chest press, pec fly, etc., which ultimately serve in purpose to adduct the humerus back towards the midline of the body; hence the brief anatomy lesson. If we now begin to consider how best to train the pectoral muscles we should next ask what is the purpose of the training; for strength or for size.

Strength

Whilst multiple authors/scientists/gym goers will talk about the difference between training for strength and size with regard to how many repetitions and sets to perform and what load (%1RM) to use the most important consideration is that of neural recruitment, better termed here as: skill. Evidence (1) suggests that most movement patterns are specific. This is very clear; even practicing superficially similar tasks had no impact on the other (2). With this in mind whilst training muscles to be stronger on one exercise might have a crossover to other exercises using the same muscles, the neural pathways for performing the movement pattern itself will not. Therefore, if you are training to be king of the bench press using a free weight barbell, then you should train using a free weight barbell. If you are training to impress your gym buddies by stacking out the 600lb chest press machine, then you should train on the chest press machine, and so forth. This is most notably true where the element of balance is required (e.g. with a free weight dumbbell or barbell).

If, by chance you are training for generic strength, because you are unsure as to whether the task will be performing push-ups with someone sat on your back, or being asked to show what you can bench press then there is an even more intriguing answer. It doesn’t matter what you do….. Whilst the skill element of performing an exercise will help you to make those refining small percentage improvements on that exercise, muscular strength is transferrable. So getting stronger using dumbbells will likely increase your free-weight bench press, and so forth. The reason behind this is both scientific and logical; that a muscle doesn’t know what it is contracting against. A muscle either contracts or relaxes. It doesn’t matter if the stimulus is plate-loaded, free-weight, weight stack or body weight, etc.  A review from 2011 (3) considered multiple studies using different resistance types including free-weights, machines, cables, hydraulic, pneumatic, body-weight and partner applied resistance, and reported no significant differences between strength attainment from one exercise to another. The review suggested that the most important variable to strength increas is that of training to momentary muscular failure that is, until no more repetitions can be completed. Training to muscular failure is suggested to sequentially stimulate muscle fibres, recruiting as many motor units as possible specifically the higher threshold motor units and thus stimulating optimal growth of muscle fibres (4).

Size

If, however, you care little about the function of your pectoral muscles so long as they are of herculean proportion then there might be more specific ways to train. Two recent papers (5,6) have considered the use of MRI to measure transverse relaxation time. This essentially means the specific parts of the muscle in activation when performing an exercise, increasing in evidence with load, number of repetitions and electrical activity. The results of the two studies (5, 6) suggested that areas of the muscle which showed higher activation throughout an exercise responded with greater hypertrophy, that is those areas of the muscle grew bigger to a greater degree than other areas. This seems logical that it is the motor units and thus muscle fibres we activate during training that are stimulated to respond by growing bigger. However, we should be cautious of applying this knowledge. Previous research has used surface electromyography (EMG) to measure the electrical activation of muscle areas when performing variations of chest exercises (7), and whilst the result might be suggestive of growth in those areas of the muscle, there is no evidence to support this. Surface electromyography (EMG) consists of placing electrodes on parts of the muscle which read the electrical activation. However, there are considerable limitations; if multiple muscles are spaced close to each other then the electrical signalling reported on the device does not differentiate from which muscle it came only the amount of activation, if motor units are closer to the surface of a muscle and thus the electrode they report a higher reading than deeper motor units, as well as being hindered by different amplitudes, muscle fibre length, velocity and contraction types (8, 9).

So what does all this mean? Well basically it means that you can choose whichever chest exercises you enjoy the most, however you must place some importance on variation. It is likely that different chest exercises activate different parts of a muscle due to the way the limbs move and forces act. Based on this there is a general suggestion that training using a mix of compound and isolated exercises might be best. This might be performed in different ways; e.g. performing multiple chest exercises in one workout, or varying the chest exercises you use from workout to workout. The benefit of this kind of training is that you are permanently challenging your body with an array of different exercise, however a limitation is that if you are following your strength gains as well then it might be a few sessions before you get back to your original exercise where you last recorded strength.

If there is a single take home message from this article it is that muscles respond in both strength and hypertrophy by stimulating as many motor units and muscle fibres as possible, therefore your choice of resistance, be it body-weight, free-weight or machine, as well as your choice of exercise is of secondary importance to the intensity of effort with which you train.

References

1. Drowatzky JN , Zuccato FC. Interrelationships between selected measures of static and dynamic balance. Res Q 1967; 38: 509-10.
2. Mount J. Effect of Practice of a throwing skill in one body position on performance of the skill in an alternate position. Percept Mot Skills 1996; 83: 723-32.
3. FisherJ, Steele J, Bruce-Low S, Smith D. Evidence-Based Resistance training recommendations. Med Sport 2011; 15(3): 147-162
4. Carpinelli R. The size principle and a critical analysis of the unsubstantiated Heavier-is-better recommendation for resistance training. J Exer Sci Fit 2008; 6: 67-86
5. Wakahara T, Miyamoto N, Sugisaki N, et al. Association between regional differences in muscle activation in one session of resistance exercise and in muscle hypertrophy after resistance training. Eur J Appl Physiol 2012; 112: 1569-1576
6.  Wakahara T, Fukutani A, Kawakami Y, et al. Nonuniform Muscle Hypertrophy: Its relation to muscle activation in training session. Med Sci Sports Exerc 2013;
7. Barnett C, Kipper V, Turner P. Effects of variations of the bench press exercise on the EMG activity of five shoulder muscles. J Strength Cond Res 1995: 9(4): 222-227
8. De Luca C, Merletti R. Surface myoelectric signal cross-talk among muscles of the leg. Electroen Clin Neuro 1998: 69: 568-575
9. De Luca C. The use of surface electromyography in biomechanics. J Appl Biomech 1997: 13: 135-63.

James Fisher