The huge muscles sculpted by bodybuilders, action movie stars and other serious gym goers can make them look like comic book superheroes. And we tend to equate big muscles with strength and power. But new search found that – at the cellular level – the large, defined muscles seen in bodybuilders do not fare well against those of power athletes (such as weightlifters or sprinters, whose sport requires high forces produced quickly) or even men who don’t train at all.
The research, published in Experimental Physiology, was conducted on individual muscle cells taken from a group of volunteers including 12 bodybuilders, six power athletes and 14 control subjects (average, physically active men who do not do weight training). The researchers, led by Hans Degens of Manchester Metropolitan University, stimulated the cells and assessed the size and speed of the force produced from the resulting isometric contractions (contracting while remaining the same length). By measuring the size of the muscle cell, they were able to calculate what is known as specific force, that is, the force produced for a defined area or muscle unit. The higher the specific force, the better the quality of the muscle.
The study authors found that although the individual fibers in the bodybuilders’ muscle cells were significantly larger than those in the control group, they also had lower specific strength. This suggests that their muscles were of lower quality than those of the controls. Power athletes, who also used resistance training but lifted lighter weights faster, had muscles of similar quality to controls, but were able to produce force faster, meaning their muscles were more powerful.
Weighing the findings
Although the authors did a fantastic job on this study, the results need to be put into context. Our skeletal muscle fibers do not function in isolation, but as part of a larger body system. Weight lifting can increase skeletal muscle size, but it can also improve support function connective tissues and blood vessels and the ability to engage the the nervous system to make more use of available muscle.
This means that lower specific strength at a microscopic level does not necessarily equal lower quality muscle or impaired function at the whole body level. It should come as no surprise, then, that former bodybuilders were able dominate strength competitions while retaining a large part of their volume.
Physiologists have known for decades that a strong but imperfect and complex relationship exists between the size of a muscle and the force it can produce. Generally, the bigger the muscle, the more force it can produce. However, some studies noted that larger muscles do not have an equivalent improvement in specific strength.
This means that as muscle grows there is not an equal increase in muscle quality. It’s the thought be due to changes in muscle architecture or a dilution of the proteins that perform the work of muscle contraction. Similar results occur when muscle size is increased with increasing doses of anabolic steroids or testosterone.
Quality over quantity
It appears that there is an optimal size for a muscle, above which increases in size do not necessarily lead to the same relative improvements in strength. The new study shows that this relationship exists at the microscopic cellular level of muscle. This also means that neither muscle size nor an individual muscle cell can be used to accurately predict its strength. However, bodybuilders are typically extremely genetically gifted athletes who spend hours every day eating and training for muscle growth. It is unlikely that the average athlete will ever reach the muscle fiber size that would lead to this dilution in strength.
The situation is different for strength athletes, who train with weights in a very different way of bodybuilders. While bodybuilders train to build muscle to their genetic potential using diet and sometimes medication, power athletes try to maximize strength at a specific body weight. Differences in training strategies combined with a consistent need to maintain weight within a given category likely prevent power athletes from building muscle to the sizes seen in bodybuilders.
In a prime example of the differences in strength between a strength-oriented athlete and a bodybuilder, former squat world record holder Fred Hatfield was able to lift over 200 lbs (90 kg) more than bodybuilder Tom Platz in a competitive squat-offdespite visually much less impressive legs.
These kinds of anecdotal reports, along with recent research, make bodybuilders look like the paper tigers of the weightlifting world. However, they are still incredibly strong by average standards and have the ability to become world record holders. When it comes to a muscle’s response to weightlifting, size may not be everything, but it’s not a bad guide.