You Really Can Exceed Your Limits

In the 1960s, Bruce Lee famously said, “If you always put limits on everything you do, physical or anything else, it will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.” It's likely that The Little Dragon had no idea about related exercise science research on limits going on at George Williams College in Chicago and published in 1961, since he was then living in Seattle and enrolled at the University of Washington.

We now know that our performance and capacity are not rigid but rather flexible and vary depending on many factors. Sometimes we are capable of more but do less, and sometimes we do far more than ever seemed possible. But are there real limits on our capabilities? This was a main theme in my Becoming Batman book and something that has always fascinated me.

Much ado about muscle force

In 1961, Michio Ikai and Arthur H Steinhaus published a paper in the Journal of Applied Physiology with the simple title, "Some factors modifying the expression of human strength." Although more than six decades old, this paper has a legacy of ongoing impact, with over 500 citations as recently as 2025.

These scientists wanted to better understand conditioning factors that might lead to the production of greater muscular forces in humans and especially using that as a measure of will or determination. They first looked at how much force could be measured when participants did maximal isometric biceps contractions and assessed the impact of various factors applied before contractions occurred. These factors were pretty extreme and included: loud shouting by the participants, the sudden firing of a .22 caliber pistol just before contraction, hypnosis suggesting "weakness," hypnosis suggesting "strength," alcohol consumption, amphetamine ingestion, and adrenaline injections. It's the last two in that list that are rather problematic from a safety perspective and would absolutely sink any modern-day attempt to recreate this study, regardless of voluntary participation and informed consent.

The basic result was that force can be significantly altered by factors that affect motivation, determination, and drive. They wrote that "in every voluntarily executed all out maximal effort, psychological rather than physiological factors determine the limits of performance." We now know that this is somewhat overstated since, in actual fact, adrenaline and amphetamines do have complex effects directly affecting the ability of muscles to produce force, so are not truly independent. Yet, the main takeaway is pretty clear: We can do more than we think we can.

Do we need to get hysterical?

"Hysterical strength" anecdotally describes extreme performances in high-stress situations that greatly exceed what we would normally imagine a person being able to produce and which wouldn't be possible to reproduce in calmer circumstances. When we truly must, in so-called "fight or flight" situations, we are able to exceed our limiters (experienced as pain, discomfort, anxiety, etc.) and truly produce a real maximal effort. The research study above showed changes in muscle force of about 30 percent, but if you increased force in many muscles across the body by that same factor, you would have a pretty large actual change in capacity.

Repeated exposure to such extreme stressors that produce "hysterical strength" would be problematic. All physiological systems have safety limits, and if we exceed those limits, we can hurt ourselves or damage our bodies. If we were at maximum all the time, we would not live very long because of the damage we could cause. All animals have a "working range" that is quite below the maximum "red line" as a protective adaptation. But perhaps a more relevant application is not the most extreme scenarios many of us will never face, but rather our daily efforts to go beyond.

Practice and pushing beyond daily limits

A portion of accessing these limits differs across people and is almost certainly "trainable." Extreme endurance or power athletes, for example, almost certainly activate more and longer than is usually found in untrained folks. In fact, one participant in the 1961 study was described as an "experienced weight lifter." He was one of the few participants who was largely unaffected by factors that increased strength in others.

The mechanistic underpinning here is essentially disinhibition, which means turning off something that would normally keep something else in check. We tend to think that we are trying to do something rather than remove something that will allow something else to occur. Yet physiologically and psychologically, this is how most systems function. In an interesting behavioral-to-tissue-level parallel, note that the main molecular limit to the actual size that muscles grow and how strong they become is the genetic limiter myostatin. In animals (including humans) with myostatin gene deletions, muscles are "free" to grow much larger than typically observed because the molecular limit regulator has been weakened.

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In everyday life, how we might access our true capacity lies in a "risk/reward" decision: Is it worth it? In emergencies, the answer is yes. In our everyday lives, we have to make that determined choice on a daily basis for our typical behaviors. This underscores the importance of state of mind for getting rid of barriers and simply doing the thing. The main takeaway for application in daily living brings us back to Bruce Lee. If we do want to improve on something, we need to focus on mindfully doing more than we previously thought we could do, or even imagined might be possible. To get there, we can be inspired further by the Little Dragon in "using no way as way" and "no limit as limitation."

(c) E. Paul Zehr (2025)