Why You're Getting Stronger.

We're back. With another article from James Kennedy - who actually has his own instagram now, you can see that here.

For competitive strength sports athletes, the aim of the game is to get as strong as possible. A key question then is, how and why do we get stronger? This question is essential to understand; without understanding this it is difficult to understand what we need to do in training and why it will work. 

There are a large number of factors which influence strength output for a given muscle group, from innate physical characteristics (such as limb length or muscle insertion sites) to adaptive characteristics (neural adaptations to force output and skill with lifting). These factors can change over time as well. New lifters tend to make rapid strength gains due to a combination of neural adaptations and skill development; the so-called noob gains. However, once you have passed through this phase (although this can last for a long time in some lucky people) there is a very strong relationship between muscular hypertrophy (muscle growth) and strength gains. 

To understand why this occurs, let's first delve into what’s happening in the muscle during a contraction to produce force.

Muscles can be broken down into a hierarchy of structures. The base of the hierarchy is two proteins - actin and myosin - which interact during muscle contractions. The myosin converts chemical energy released from amino triphosphate (ATP) into mechanical energy which pulls the actin filaments along the myosin filaments, causing muscle contractions. Thousands of actin and myosin proteins are found within a single sarcomere; a collection of sarcomeres forms a muscle fibre and a muscle is formed of thousands of muscle fibres. 
The microscopic level contraction - relaxation cycles of actin and myosin leads to the macroscopic level muscular contractions. The muscles are attached to the skeleton by tendons, and as they contract the skeleton moves. 

Muscles generally attach to the skeleton at two points - the origin and insertion. The origin of a muscle is the attachment site which doesn’t move during contraction. The insertion of a muscle is the attachment site which does move during contraction. Taking a bicep as an example; when you perform a bicep curl, the bicep contracts. This results in the forearm moving around the elbow joint, where the bicep muscle inserts. The shoulder remains still, which is where the bicep muscle originates.

Depending on the muscle group and type of joint they insert into - muscle fibres run at different angles. This angle, known as the pennation angle, controls the number of sarcomeres which can contribute to a given contraction. As pennation angle increases a greater number of sarcomeres can contribute to a given contraction - therefore a muscle with a larger pennation angle will be stronger than a muscle with a smaller pennation angle. Taking a line perpendicular to the pennation angle across the largest part of a muscle allows us to calculate the muscle's physiological cross-sectional area. Muscle cross-sectional area is directly proportional to the amount of force which can be produced by a muscle. 

Why does this matter for lifters? You can’t change the pennation angle - the angle at which muscle fibres insert into joints. However, you can increase the number of muscle fibres you have. The more muscle fibres you have, the larger your muscle cross-sectional area is and the greater force you can produce with that muscle. 

So how do we increase the number of muscle fibres? Resistance training! 


So, if you want to get stronger consistently over an extended period, you will need to increase the amount of muscle mass you have. As a strength athlete, you will also want to increase the amount of force your muscle can produce - so you have a larger muscle with more muscle fibres and each muscle fibre can produce more force. Training style can influence this; it is possible to have muscular hypertrophy and have fewer strength gains due to the muscle producing less force relative to the muscle size. Muscle force production is measured using Normalised Muscle Force (NMF); studies have mostly shown that it increases due to strength training. However, it does not increase the same for all groups. Comparisons between the amount of NMF produced by weightlifters' triceps, who train them primarily with a low rep, high weight movements like the jerk and overhead press, and bodybuilders, who trained triceps primarily with a higher rep, low weight movements, found that the weightlifters produced more force per unit area of muscle than the bodybuilders. 

Translating that into plain English; per unit of tricep muscle mass, weightlifters were able to generate more force than bodybuilders. This is likely due to the nature of the training differences between the groups. Note, that NMF is independent of muscle size - it is just related to the strength of the muscle. Ideally, we would like to be able to get a bigger muscle which could produce the same amount of force per unit area - growing both NMF and the number of muscle fibres.

To increase the number of muscular fibres and overall muscle size, there are two broad strategies - focussing on high reps with lower intensities or training with higher loads and slightly lower rep ranges. As strength athletes, we want to increase both the number of muscle fibres we have and the amount of force we can produce per unit area of the muscle, the NMF. Consequently, hypertrophy-based training for strength athletes should be focused in the range of 70-85% of one-rep max, aiming to get 20-35 reps per exercise. This would lead to some classical ‘power building’ rep ranges such as 3x10, 4x8 or 5x5. 

The weights used should also increase over time; progressive overload is essential for driving hypertrophy. The simplest way to achieve progressive overload is to just add a small amount of weight to each workout. Alternatively, you can keep the weight the same, but just increase the number of reps per set. Combined with eating a diet high in protein (diet article link), this will lead to muscular hypertrophy. As larger muscles have the potential to be stronger muscles, over time progressively overloading and growing muscles will make you stronger. Further, training in a higher intensity style will help you increase the amount of force your muscles are capable of producing per unit area, increasing the carryover from muscular hypertrophy to strength sports.

Summary

Whilst multiple factors influence strength beyond muscle size and force production, there aren’t a huge amount of things you can do about them. The innate physical characteristics, such as muscle insertion sites, limb length, and the angle of insertion of the muscle, are fundamentally unchangeable. New lifters typically make very quick gains in strength without experiencing a large amount of muscular hypertrophy due to neural adaptations and rapid skill acquisition and development. However, once this phase is over and lifters move from beginners to intermediate-advanced trainees, muscular hypertrophy is much more important to strength gains. Fundamentally, strength athletes should be attempting to grow as much muscle as possible to produce the most muscular force possible and lift the most possible weight. The training style is also important - training in lower rep ranges with higher intensities is essential to maximising the amount of force muscle can produce. Subsequently, strength athletes should be training in the 70-85% of one-rep max, with 20-35 reps per workout. 

Chasing muscular hypertrophy whilst lifting heavy weights will help you keep progressing in your strength sports career. A bigger muscle has more muscle fibres, which can be trained to contract harder, allowing you to lift more weight and break more PBs. Fundamentally, the more muscle you have the more weight you should be able to lift and the stronger you will be!

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