You don’t have “hidden” strength for extreme situations
You may have heard of the mother who could lift a car to save her child from death. This example is often used to illustrate that, with enough emotional stress and adrenaline, we can unleash our “hidden” amount of super strength. Scientifically, however, we need more to be convinced.
We willingly use our nervous system to activate our muscles. This is known as voluntary contractions. We can also use electrical devices to stimulate all relevant parts of our nervous system to activate our muscles. This is known as evoked contractions, which would be our theoretical “maximum” ability to contract our muscles.
A study comparing voluntary to evoked contractions in single muscles in untrained individuals found that voluntary contraction activates >90% of muscle fibers resulting in >95% of our evoked strength. Thus, there is not much room for extra strength in SINGLE muscles, namely only 5%. It is unclear if this 5% is even lower in well trained individuals.
It is still possible that more complex moves involving coordination of many muscles can improve with emotional stress, but you can probably understand ethically why we cannot conduct a study where we stimulate evoked contractions of a deadlift.
Take home: Most people activate their muscles very effectively in the first place. So trying to activate your muscles more is not the way to go if you want to get stronger. There is more your can do, however. Check out our blog for more posts on the topic. Link in bio.
Noorkõiv M et al. Neuromuscular adaptations associated with knee joint angle-specific force change. Med Sci Sports Exerc. 2014 Aug;46(8):1525-37.