Muscle hypertrophy – increasing muscle size/promoting muscle growth. Probably the most popular reason for most people joining gyms and/or beginning lifting (alongside fat loss). Gaining lean muscle mass makes you look better and feel better, it’ll also help with fat loss (muscle tissue is highly metabolic/’energy hungry’) and can lead to improvements in strength and power – and therefore sports performance.
Many people join gyms, begin a programme and see results fairly quickly, and these results continue for a few months until the ‘beginner gains’ plateau is hit. At this point things slow right down, frustration sets in, and the person will inevitably quit or at best end up stuck in a rut, miserable, and paying an expensive gym membership for nothing. This usually occurs because trainers and trainees have no understanding of how to trigger muscle hypertrophy (following the initial ‘honeymoon’ period of being a beginner), and therefore don’t really know how to write an effective, science-based programme that progressively produces results and avoids plateaus.
There’s been a plethora of research on muscle growth over the past decade in an attempt to fully understand how hypertrophy occurs and, although it’s difficult to determine for certain, several researchers have some fairly good ideas. One of these researchers is Brad Schoenfeld (http://www.lookgreatnaked.com/), who published an excellent study in 2010 titled “The mechanisms of muscle hypertrophy and their application to resistance training”. This blog post is heavily based on that article and others by Brad Schoenfeld and Bret Contreras.
Definitions
As previously stated hypertrophy simply means muscle growth and is the opposite of muscle atrophy (muscle loss).
Hypertrophy has two secondary categories;
Transient Hypertrophy – the short lived, post-workout ‘pump’
Chronic Hypertrophy – long term lasting gains, actual changes in muscle architecture (i.e. what we’re training for)
Chronic hypertrophy occurs in two ways according to research –
Contractile/Myofibrillar/Functional Hypertrophy – This involves the addition of sarcomeres (basic muscle units) in parallel. Contractile elements (actin and myosin) also enlarge and multiply and the extracellular matrix (everything else inside the cell) expands. This is deemed ‘functional’ as the tissue that is hypertrophied and supplemented is ‘contractile’ and thus capable of contracting and generating force. This is ‘powerlifter hypertrophy’ to put it simply.
Non-contractile/Sarcoplasmic/Non-functional Hypertrophy – This is the increase in size of the non-contractile elements inside the muscle cell (collagen, glycogen) and sarcoplasmic fluid. This is ‘non-functional’ as it doesn’t directly involve changes to the contractile elements and therefore doesn’t produce changes in force expression. This is ‘bodybuilder hypertrophy’ – big but not necessarily strong. This form of hypertrophy can have knock-on effects which promote contractile hypertrophy – hydration and thus cell swelling may lead to subsequent cell growth due to pressure on the cell wall.
Mechanisms
In order to get bigger we need to maximise protein synthesis (create an anabolic environment) and minimise protein breakdown/catabolism. Multiple mechanisms/factors are proposed for this.
Three Main Factors
- Mechanical Tension
- Muscle Damage
- Metabolic Stress
Mechanical Tension
This is a combination of force generation and stretch. It’s the amount of tension that muscle fibres produce when a load stimulus is introduced.
Mechanical tension disturbs the integrity of skeletal muscle, it facilitates molecular and cellular responses that trigger hypertrophy.
There are two types of muscular tension:
– Passive tension – which occurs during eccentric contractions (‘stretching’ a muscle under load)
– Active tension – relating to the contractile elements of the muscle. Occurs during hard, forced contractions of a muscle (i.e. lifting heavy stuff).
Muscle Damage
This is localised damage to the muscle tissue caused by novel/unfamiliar exercise, slow eccentrics (lowering part of the exercise), or forced stretching of a muscle whilst it’s in an activated/contracted state.
It creates ‘myotrauma’ (muscle trauma) which triggers an acute inflammatory ‘healing’ response that stimulates growth factors that mediate and promote hypertrophy.
Metabolic Stress
Putting a muscle under repetitive, sustained stress causes metabolite accumulation which triggers an anabolic response (raises testosterone, IGF-1, growth hormone, and mechano growth factor).
Metabolic stress can be induced best via anaerobic glycolysis (hard, intense exercise with limited amounts of oxygen, lasting 10s – 2min). This causes a build up of metabolites – lactate, hydrogen ion, inorganic phosphate, creatine (amongst others) and promotes an acidic, ischemic, and hypoxic environment in the muscle (which can also trigger hypertrophic adaptations).
All three of these elements are inter-related, and training in a way that optimises and combines all three will produce the greatest results.
Application to Training
Intensity
Train with a minimum intensity of 65%1RM (15 rep maximum), in moderate repetition ranges (6-12 reps). This prescription will cause a metabolic build up which boosts testosterone and growth hormone. It will also induce a pump (ischemia and hypoxia) which triggers hypertrophy and an increase in protein synthesis.
Additionally the more repetitions that are completed the longer the time the muscle is under tension which means more microtrauma/damage to the muscle (through eccentric contractions).
Volume
For maximum hypertrophy a higher volume, multiple set approach must be taken. Greater volume will stimulate greater growth hormone release and hypertrophy will result.
To facilitate this a body part split routine may be more beneficial that a full body routine as it will allow more regular training whilst still permitted muscles to fully recover. Again, more total reps also equates to more eccentric contractions which results in more muscle damage.
Exercise Selection
Multi-planar and multi-angled exercises must be included to allow for variance in muscular structure (i.e. fibre orientation) and to fully stimulate the entire muscle. Regular rotation of exercises will also make sure of this.
Whilst selecting exercises it’s essential to incorporate a mix of multi-joint and single joint exercises. Single joint (“isolation”) exercises will help to prevent imbalances and can develop weaker areas that may be neglected during compound/multi-joint movements.
Not all exercises are created equal, some lend themselves better to different rep ranges, different tempos, and different focuses (hypertrophy, strength, power). Certain exercises will produce a ‘pump’ effect more easily than others, some will create tension in a muscle better than others, and some exercises are more suited to slow eccentric contractions or tempos that will damage fibres.
Big, multi-joint, compound exercises are best for developing high tension in a muscle and activate the greatest amount of muscle mass – squats, deadlifts, bench presses, rows, pull ups (etc.). Incorporate variations and assistance exercises to ensure all fibres are hit.
Constant tension exercises are best for creating the pump effect – lateral raises, concentration curls, leg extensions (etc.).
Exercises that produce high tension whilst the muscle is in a lengthened state are best for creating muscle damage – dumbbell pec flyes, RDLs, incline curls (etc.). It’s important to be careful with these highly damaging exercises as, although damage is an effective hypertrophic stimulus, excessive damage can prevent you from training and cause more harm than good.
Rest Periods
Moderate (60-90s) rest will allow sufficient metabolic stress, adequate strength recovery, and create a more anabolic environment within the body.
Training to Failure
Training to concentric muscular failure is highly beneficial and should be done regularly (although not necessarily in every exercise/set), it’s important to ensure that the repetitions are still technically good (and safe) – a spotter is usually important here. Reaching failure allows the maximum number of motor units to be recruited and creates high metabolic stress.
Repetition Tempo
A moderate concentric speed (one or two seconds) with continuous muscle tension creates a greater metabolic demand than very fast or very slow repetitions. Slower eccentric repetition speeds are beneficial for hypertrophy as they will inflict more muscle damage and positively affect protein synthesis.
Intensification Methods
Employ intensification methods sparingly to push a set or exercise to the limit. These methods can include eccentrics/negatives, drop sets, rest-pause, cluster sets, supersets, tri-sets, and quad-sets. These methods can trigger additional hypertrophy stimulating signals that can lead to augmented muscle growth over time. Using this as a finisher at the end of a session for the final exercise or final set of the final exercise may be most beneficial and will limit the potential for injury.
In Summary…
Example Session Structure – Leg Day
Tension A1) Back Squat – 5×5 @ 75%1RM, 90s rest interval, 3 sec eccentric
Tension B1) Split Squat – 3×6 @ 70%1RM, 60s rest interval, 3 sec eccentric
Damage C1) RDL – 3×8 @ 70%1RM, 4 sec eccentric
Damage C2) Nordic Hamstring Curl – 3×5 @ BW, 90s rest interval, 4 sec eccentric
Metabolic Stress (“pump and burn”)
Tri Set
D1) Leg Extension – 3×12 , 3 sec eccentric
D2) Leg Curl – 3×12, 3 sec eccentric
D3) Calf Raise – 3×12 , 3 sec eccentric, 60s rest interval
High Intensity Technique Finisher
Rest Pause
E1) Leg Press – 2×10+ @ 60%1RM, 60s rest interval
References
Schoenfeld, B. J. (2010). The mechanisms of muscle hypertrophy and their application to resistance training. The Journal of Strength & Conditioning Research, 24(10), 2857-2872.
Fry, A. C. (2004). The role of resistance exercise intensity on muscle fibre adaptations. Sports medicine, 34(10), 663-679.
https://www.t-nation.com/training/why-bodybuilders-are-more-jacked-than-powerlifters
https://www.t-nation.com/training/hypertrophy-specialist
http://www.muscletalk.co.uk/articles/muscularhypertrophy.aspx
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