Was lactate really just a “fatigue substance”?

For many years, a familiar explanation was that exercise causes lactate to accumulate and that this is what causes fatigue.
It is true that blood lactate rises during intense exercise.
But research has shown that lactate is not simply a useless waste product. It can be used as an energy source, serve as a substrate for glucose production, and act as a signaling molecule.
The earlier observation did not disappear. What changed was how clearly we could understand what lactate actually does.

Muscle does more than move the body

Muscle moves bones and allows us to stand and walk. That remains true.
But skeletal muscle is now also studied as an endocrine organ that releases a wide range of biologically active substances.
These include myokines released from muscle, as well as the broader concept of exerkines—signals released from multiple tissues in response to exercise.
The old picture of muscle as a motor organ has not vanished. A new layer has been added to the picture.

Stress theory and Helicobacter pylori

In 1936, Hans Selye, later known for his work on stress, exposed rats to very different severe stressors, including cold, injury, excessive exercise, and drugs.
Despite the different stimuli, he observed a common pattern of bodily responses. These observations later contributed to his concept of the General Adaptation Syndrome.
For many years, stress, lifestyle, and gastric acid were considered important in gastric and duodenal ulcers.
Then, in the 1980s, Robin Warren and Barry Marshall demonstrated the important relationship between Helicobacter pylori and gastritis and peptic ulcer disease.
The discovery transformed the understanding and treatment of peptic ulcers, and Warren and Marshall received the 2005 Nobel Prize in Physiology or Medicine.
Did that make all earlier stress research wrong? Not quite.
Today, H. pylori infection and NSAIDs are recognized as major causes of peptic ulcers, while the physiological effects of stress on the body have not simply disappeared from medical science.
The answer did not change from “stress” to “H. pylori” in a single step. Bacteria, medicines, nerves, hormones, immunity—more of the background became visible.

We became able to see the multiple factors behind one disease in greater detail.

That may be what it means for medicine to gain resolution.

Pain does not always mean “damage here”

Our understanding of pain has also changed.
Tissue injury can certainly cause pain. But tissue damage alone cannot explain every pain experience.
In 2020, the International Association for the Study of Pain (IASP) revised its definition of pain, describing it as a personal sensory and emotional experience influenced to varying degrees by biological, psychological, and social factors.
IASP also emphasizes that pain and nociception—the neural process of detecting potentially harmful stimuli—are not the same phenomenon.
The approach to low back pain has changed as well. “It hurts, so rest completely” is no longer a sufficient general rule.
For chronic primary low back pain, WHO recommends a combination of approaches that may include exercise, education that supports self-management, psychological interventions, manual therapies, and medicines when appropriate.
Instead of looking only at the painful location, medicine now considers peripheral nerves, the spinal cord, the brain, psychological factors, and the person’s environment. The field of view itself has widened.

There is more than one kind of “fact”

It is important not to treat every kind of fact as if it were the same.
There are findings that have been examined scientifically and are currently supported by a body of evidence.
There is also the historical fact that certain therapeutic systems have been practiced, recorded, and transmitted over long periods of time.
And in clinical practice, we sometimes observe changes directly: “It hurt a moment ago, but now it doesn’t,” or “That joint could not move before, but now it can.”
These are not the same kind of fact.
A treatment being handed down for centuries does not prove that it is effective. Pain disappearing after acupuncture does not by itself prove that acupuncture caused the change. And evidence of benefit in clinical trials does not prove an entire traditional medical theory.

What is observed and what has been proven about its cause are different things.

But if we cannot yet fully explain a phenomenon, we do not need to pretend that the observed phenomenon never happened.
First, observe. Then ask, “Why?”
Perhaps that is where medicine and science have always begun.

So what about acupuncture and Kampo?

It is a historical fact that acupuncture and Kampo have been practiced, recorded, and transmitted over long periods of time.
Of course, longevity alone does not make a treatment correct.
At the same time, acupuncture is now being studied from many perspectives, including the nervous system, local tissues, and the brain’s processing of pain.
For pain, the strength of evidence varies by condition and study design, but there are areas in which research has accumulated showing potential or demonstrated benefit.
In Japan, the Japanese Association for the Study of Pain has also established a certification system for acupuncturists, with efforts to support multidisciplinary collaboration in pain care.
This does not mean that “acupuncture has been scientifically proven” as a whole.

It means that acupuncture is increasingly being studied, evaluated, and considered for an appropriate role within health care.

Kampo is undergoing a similar process. The Japan Society for Oriental Medicine has continued to compile the Evidence Reports of Kampo Treatment (EKAT), which collect and evaluate randomized controlled trials and meta-analyses of Kampo products.
Globally, WHO adopted its Global Traditional Medicine Strategy 2025–2034 and, in 2026, published global research priorities for traditional, complementary, and integrative medicine.
The goal is not to declare the questions settled, but to strengthen evidence on effectiveness, safety, regulation, and appropriate integration.

Traditional medicine and modern science are gradually moving closer to one another.

Yet much remains unknown. That is precisely why research and verification continue.

When we do not know, keep asking

In acupuncture practice, pain can sometimes change markedly after treatment, or a movement that was difficult may suddenly become easier.
Of course, sometimes there is little or no change.
And even when a change occurs, we cannot always explain exactly why.
Was it the nervous system? The brain? Local tissue? Circulation?
Were psychological and contextual factors involved as well? Were several mechanisms interacting?
We do not always know. But the change observed in front of us may still be real.

How will people 100 years from now see today’s medicine?

Medical common sense 100 years ago was not the same as it is in 2026.
So when people in 2126 look back at us, they may be surprised by some of the ways we understood the body.
Some ideas we now take for granted may be rejected. Mechanisms may be discovered for phenomena that we cannot yet explain.
Our scientific understanding of acupuncture and Kampo may also look very different.
So rather than blindly trusting the old or treating the new as absolute, I want to keep asking: How much can we actually see right now?
Read the classics. Read contemporary research.
And observe the body in front of us.
Keep different systems distinct, compare them carefully, and continue thinking.
Common sense changes.
Perhaps that does not mean everyone before us was simply wrong. Perhaps our resolution for seeing the world has simply increased a little more.