The Benefits of Stretching for Mass Gains

School Of Personal Training Posted Apr 26, 2016 Future Fit Training

Katie Farnden looks at stretching, different types of stretches and how it can impact building muscle and the science behind it.

The Benefits of Stretching for Mass Gains

The stretching element of a workout is often seen as a chore or not essential, especially if the aim of the fitness enthusiast is simply to build muscle. Those that do incorporate it are often confused as to what type of stretching to do and when.

However, can stretching help to build more muscle?

Well, muscle is encased in strong connective tissue called fascia.  The purpose of this binding is to support the muscles in place, like a sausage wrapped in the skin. This strong muscle fascia restricts the muscle's opportunity to expand, inhibiting it's ability to grow no matter how on point a person’s training regime may be. The restrictions are then increased even more by the trainee neglecting post workout stretches. Muscles then become tight as the fascia constricts, leading to both the muscles and fascia becoming stiff, mis-aligned and immobile over time. Some of the consequences of this include the increased likelihood of injuries and limited movement.

In comparison, by stretching before, during and post workout, neuromuscular and metabolic reactions are heightened, including the stimulation of protein synthesis due to the added mechanical stress placed on the muscles.  With the added ability to increase their range of motion, the progression of exercises with safe and correct technique are welcomed.  The increased elasticity also enables the fascia to act as a spring to generate more force to support the possibility of a larger cross sectional area for growth.  This has been researched and evaluated in numerous studies, and even though the tests were not always subjected to humans, results have shown an increase in muscle mass, with adaptations to enzymes and hormones also apparent[1]. This opportunity for increased mass and power output can then be seen to directly contribute to the enhancement of muscular performance, with muscles that are less likely to fatigue as quickly under load.


For optimal performance during resistance training, the muscles need to have the ability to contract and relax through the various movements.  When muscles are tight from exercise induced muscle damage, stretching can help to overcome the restrictions so that the workout can continue effectively. Therefore, the inclusion of certain stretches is paramount.  The practice of static stretching is believed by many to reduce muscular strength and power, decrease blood supply and fatigue muscles[2]. Whilst this had not been continually proven, dynamic stretches are still favoured, as they are excellent at firing up the nervous system. They can also be geared to include specific movement patterns that mimic a sport, exercise programme or individual needs. Whilst they are less effective at increasing flexibility, this is not the aim pre-workout.  Instead, the muscle is encouraged to stretch then contract to increase the range of movement whilst exerting force in it's lengthened position. This will then also serve to aid power output during the workout more so than the better known static stretching or even worse, no stretching at all.

Intra-workout stretching

Ideally we want to overload both the fascia and the muscle fibres. During resistance training the muscle fibres are able to be put under heavy stress whereas the fascia is actually under very little. To help ensure this we can follow certain stretching recommendations, including the extended duration of a 'set' or 'sets' by including an isometric muscle stretch at the end of the eccentric movement, e.g. when the chest is in the stretched position during dumbbell flies, or the hamstrings during straight leg deadlifts.

Schleip et. al explains that when the muscle is dynamically activated under resistance such as weighted load, it's 'lengthened position promises the most comprehensive stimulation of fascial tissues'[3]. As the muscles become pumped up the tissue around the muscles stretch, causing nutrients to flow into the blood and into the muscles.  Why is this so great?  Well, think of your muscle as a tunnel, when the tunnel is expanded more muscle building nutrients can be transported and released.

The key for effective muscular overload then, is to firstly favour training methods that recruit type II muscle fibres (fast twitch).  These include an optimal work to rest ratio, and increased time under tension, particularly during the eccentric phase to stimulate and amass mechanical stress.

The inclusion of loaded stretching is likely to disrupt blood flow through stretch induced occlusion, and hypoxia through the consequent oxygen consumption of the working muscles. This ultimately aids in the accumulation of lactic acid and the subsequent accruement of metabolites, growth hormone and IGF-1.

The active stretching during movement can also help to maximise the opportunity for mechanical and hormonal reactions. If we refer to the relationships between such actions brought about by reciprocal inhibition, it is the contraction of the antagonist muscle that then allows the lengthening and relaxation of the agonist muscle[4].

Therefore, to contract the opposite muscle to the one being worked during or after each set could serve to keep the muscles pliable without decreasing strength. For example, to stretch the biceps, actively flex the triceps, or to stretch the quadriceps contract and flex the hamstrings as much as possible. The nervous system is then tricked into protecting the agonist by increasing the amount of motor units recruited. 

However, should this extended period of overload stop when the body is resting between resistance sets?

As previously mentioned, the ideal time to stretch for increased muscle mass is straight after a muscle has been worked and pumped up with blood. Also mentioned was the current belief that static stretching pre-workout is detrimental to strength. However static stretching between sets could prove beneficial. Research has evaluated the added influence of time under tension brought about by inter-set static stretching on trained muscles (Mohamad et al., 2011), and determined that strength improvements and hypertrophic reactions were shown continually throughout controlled studies.

However, the length of time held in the stretch should be considered.  A 6-8 second static stretch will be enough to release a muscle but longer than that will then start to decrease strength and overall performance.

Stretches post-workout

Contracting a fully stretched muscle against resistance inhibits the stretch reflex to allow a muscle to stretch further in a more developmental way.  PNF stretching facilitates this and is a good choice post workout as it uses the body’s proprioceptive system to either aid or inhibit muscle contractions[5]. This initiates a faster neuromuscular response and allows deeper stretching to take place, increasing range of motion and helping to prevent injury[6].

Once again the added mechanical stress of the stretch on an already fatigued muscle group would likely result in increased muscle damage and DOMS even though the muscles are being released and lengthened further[7].

The stretch should be held for 5 – 6 seconds, applying sufficient resistance to inhibit movement at 60-100% maximum isometric contraction. As the muscle spindles start to relax the controlled stretch can then be increased for approximately 20 to 30 seconds. This process can then be repeated for optimal results.

In conclusion, stretching pre-, intra-, inter- and post-workout can provide a host of benefits.  To keep the body and training plan at optimal performance, standard stretching cannot and should not be side tracked.  If strength and mass gains are the focus, the recommendations discussed are paramount.  The increases in mobility, muscular balance, nutrient transportation, and injury prevention are all pieces of the puzzle, whilst the stretching and overload of the fascia and consequent mechanical overload bring it to completion.

Article written by Katie Farnden


[1] Holly RG, Barnett JG, Ashmore CR, Taylor RG, and Mole PA. Stretch-induced growth in chicken wing muscles: A new model of stretch hypertrophy. American Journal of Physiology. 1980 Cell Physiology 238: p62–71

[2] McHugh MP, Cosgrave CH. To stretch or not to stretch: the role of stretching in injury prevention and performance. Scandinavian journal of medicine & science in sports. Apr 2010;20(2): p169–181 

[3] Schleip, R., Muller, D.G., Training principles for facial connective tissues: Scientific foundation and suggested practical applications, Journal of bodywork and movement therapies (2012)

[4] Kayla B. Hindle, Tyler J. Whitcomb, Wyatt O.Briggs, and Junggi Hong. Proprioceptive Neuromuscular Facilitation (PNF): Its Mechanisms and Effects on Range of Motion and Muscular Function - Human Kinetics. 2012 Mar; 31: p105–113.

[5] Antônio Claudio Souza, Claudio Melibeu Bentes, Belmiro Freitas de Salles, Victor Machado Reis, José Vilaça Alves, Humberto Miranda, and Jefferson da Silva Novaes. Influence of Inter-Set Stretching on Strength, Flexibility and Hormonal Adaptations. Journal of Human Kinetics. 2013 Mar; 36: p127–135.

[6] Nelson AG, Chambers RS, McGown CM, Penrose KW. Proprioceptive neuromuscular facilitation versus weight training for enhancement of muscular strength and athletic performance. Journal of Orthopedic Sport Physiology. 1986;7(5):p250–253.

[7] Feland JB, Marin HN. Effect of submaximal contraction intensity in contract-relax proprioceptive neuromuscular facilitation stretching. British Journal of Sport Medicine. 2004;38(4):p18

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