Is bigger...stronger?

By Perry Stewart

People participate in resistance training for many reasons: improved health, athletic performance, rehabilitation and, in some cases, vanity. For those spending an incomprehensible amount of time in the gym, carrying their protein shaker and continually sneaking a peek at themselves in the mirror, hypertrophy (increase in size of muscle tissue) for aesthetic reasons appears to be the aim. However, just because someone has larger muscles, does this mean they are stronger?

So consider two athletes:

  • Shevon Cunninghan (74.5–79kg) is World Natural Bodybuilding Federation (WNBF) Middleweight Champion.
  • Lu Xiaojun (77kg) is current world champion weightlifter and world record holder for the snatch (174 kg) and total (378kg).

Of these two athletes of similar body mass, you can be forgiven for thinking that Shevon is stronger due to his muscular hypertrophic physical appearance; however, despite being strong, he cannot lift anywhere near the same amount of weight as the Lu. This naturally leads us to ask, how can individuals with less muscle mass be stronger than those with bulkier muscles?

A combination of factors

This article does not dispute the fact that hypertrophy plays a significant part in force production. Structural adaptations to the muscle, such as increased crosssectional area (CSA) and to a lesser extent hyperplasia are clearly a contributing factor in strength. However, one aspect of hypertrophy is an increase in volume of fluid within the muscle cell ('sarcoplasmic hypertrophy') – this swelling is why your muscles are biggest straight after a session. This results in greater muscle bulk but not subsequent strength gains.


Types of hypertrophy

  • MUSCULAR HYPERTROPHY = an increase in size of (existing) muscle cells. There are two types:
    i) myfibrillar hypertrophy is an increase in the number of contractile proteins AND a consequent increase muscular strength, mostly associated with weightlifters
    ii) sarcoplasmic hypertrophy is an increase in sarcoplasmic fluid WITHOUT an increase in muscular strength, mostly associated with bodybuilders
  • MUSCULAR HYPERPLASIA = increase in the number of muscle cells. Contribution of muscle hyperplasia is small (<5%) [1].



The hard science

As hypertrophy increases, so too does the pennation angle of the muscle fibres. This may reduce the total force production of the more oblique fibres. Therefore, increasing muscle bulk possesses the potential for diminishing returns in relation to strength.


How to get stronger, not bigger?

Generally, the contribution of the nervous system in force production is given little attention. However, the definition of strength is the maximum force produced via the neuromuscular system. Therefore, strength gains can also be attributed to adaptations in nervous system function. In fact, the initial accelerated strength gains seen in untrained individuals are almost exclusively attributed to this. Increased force production can be explained through several neuromuscular mechanisms: Recruitment, Rate Coding, Synchronisation and Neural Inhibition.

Recruitment

The force of a muscular contraction is dependent upon the recruitment and activation order of motor units. These consist of a motor neuron at the spinal cord, a long axon that transmits nerve impulses, and all the muscle fibres it innervates (stimulates through the nerves). The body will initially activate the smallest motor neurons with the lowest firing threshold. It is only when the force builds up that the number of active motor units increases and recruitment of faster motor units is achieved. Those involved in strength training demonstrate increased motor unit activation, enabling them to exert higher total force [1].

Rate coding

This refers to the firing frequency of the motor neuron. Simply put, the faster the muscle fibres are innervated, the greater the force production of the muscular contraction. It is widely accepted that even short periods of strength training cause an increase in neural drive to the muscle fibres [2].

Synchronisation

Normally, motor units work in a co-operative sequence, but individually, to produce a smooth, accurate movement. However, it is believed that during maximal efforts motor units are activated simultaneously, resulting in a more forceful contraction. Groups of motor units are thus working together to coordinate the contractions of a single movement and therefore their force is combined [3].

Neural inhibition

It has been suggested that neural protective mechanisms (most notably the golgi tendon organ – GTO) are present during maximal eccentric contraction, and limit recruitment and/or rate coding. However, heavy resistance strength training has been shown to reduce these neural inhibition mechanisms and consequently enhance strength and speed of muscular contractions [4].

Strength training tactics

Maximal muscle strength has been shown to increase by 20–40% (over 8–16 weeks) in response to heavy resistance strength training – this is without increases in muscle CSA [3]. Findings from a meta-analysis (statistical analysis of all previous relevant research data) reported the most effective strategies for maximal strength gains [5] in Table 1 below.

Strength training interventions such as these are especially important for athletes who compete at weight-regulated sports. For example, a boxer wants to be as strong as possible; however, if they get stronger through hypertrophy, their weight goes up and ultimately they could be fighting a bigger opponent! Therefore, these athletes require high amounts of strength relative to body mass for optimal performance.

Novice Amateur Professional
Untrained individuals Trained individuals Highly trained individuals (athletes)
Intensity: 60% of 1RM Intensity: 80% of 1RM Intensity: 85% of 1RM
Volume: 4 sets per exercise Volume: 4 sets per exercise Volume: 8 sets per exercise
Frequency: 3 days per week Frequency: 2 days per week Frequency: 2 days per week

Table 1. 1RM = 1 repetition maximum

Force positive...

It should now be acknowledged that muscle size is not the only indication of strength; adaptations to the nervous system are fundamental to increasing force production. Maximising strength gains without concurrent hypertrophy is the primary goal for many individuals. This will impact on the application of resistance training strategies. These can be summarised as high-intensity, moderate-volume strategies – although specific application is relative to training history.

References

1. Zatsiorsky VM, Kraemer WJ. Athlete-specific strength (Chapter 3, pp 47–65), in: Science and Practice of Strength Training. Human Kinetics, Champaign, Illinois, 2006.
2. Aagaard P. Neural adaptations to resistance exercise (Chapter 2.1, pp 105–124), in: Strength & Conditioning: Biological principles and practical applications. Wiley–Blackwell, Oxford, 2011.
3. Aagaard P, Simonsen E, Trolle M et al. Specificity of training velocity and training load on gains in isokinetic knee joint strength. Acta Physiologica Scandinavia, 1996, 156, 123–129.
4. Aagaard P, Simonsen, EB, Anderson JL et al. Neural inhibition during maximal eccentric and concentric quadriceps contraction: effects of resistance training. J Appl Physiol, 2000, 89, 2249–2257.
5. Peterson MD, Rhea MR, Alvar BA. Applications of the dose-response for muscular strength development: a review of meta-analytic efficacy and reliability for designing training prescription. J Strength Cond Res, 2005, 19, 950–958.

Correspondence

Perry Stewart is a Strength & Conditioning Coach and Lecturer at the London Sport Institute.

Please contact Perry with your comments and queries:
Email: p.stewart@mdx.ac.uk


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