Hill and Meyerholf received the Nobel Prize for their research into how muscles generate heat and convert glycogen into lactic acid | Image used for illustrative purposes only | Photo credit: Soumyadeep Sinha.
Archibald W. Hill and Otto Meyerhof studied how muscles use chemical energy to contract and repair. Hill measured the heat generated by working muscles, and Meyerhof traced the relationship between oxygen consumption and lactic acid metabolism. Their work earned them the 1922 Nobel Prize in Physiology or Medicine.
The prize was divided equally. Hill was awarded “for his discovery of heat production in muscle” and Meyerhof was awarded “for his discovery of the constant relationship between oxygen consumption and lactic acid metabolism in muscle.” The prize was awarded for 1922, but was awarded in 1923 because the Nobel Committee initially decided that none of the 1922 nominations met the required criteria.
Measuring muscle heat
Hill approached muscle physiology as a problem of both physics and biology. Working primarily with frog muscles, he developed precise methods for measuring the very small amount of heat generated during contraction.
The changes were minor. In one experiment described in his Nobel lecture, a single contraction of the frog’s sartorius muscle at 20°C increased its temperature by no more than about 0.003°C. Hill used sensitive instruments and carefully controlled contractions to separate the heat generated during activity from the heat generated during recovery.
His measurements showed that heat production does not stop when the muscle stops contracting. The second phase, which Hill called reducing heat, continued after the contraction and was dependent on oxygen. When the oxygen was removed, this reducing heat disappeared.
This was important because it showed that the energy changes associated with muscle contraction and recovery occur in separate phases rather than as one continuous process.
Meyerhof traces chemistry
Meyerhof investigated the chemical side of the same problem. In experiments on frog muscles, he measured heat production and oxygen consumption, and also monitored the conversion of carbohydrates into lactic acid.
He showed that during muscle activity, lactic acid is formed from carbohydrates. During recovery, some of the lactic acid was oxidized and the rest was converted back to carbohydrates. These observations helped establish the connection between oxygen use and lactic acid metabolism, for which he received the Nobel Prize.
Meyerhof’s work went further. Between 1918 and 1922 he presented evidence that glycogen is converted to lactic acid in the absence of oxygen. He also discovered that only a portion of the lactic acid produced during anaerobic muscle activity is subsequently oxidized in the presence of oxygen, with most of the remainder being converted back to glycogen.
Two sides of muscle metabolism
Hill and Meyerhof studied different aspects of the same physiological problem. Hill measured the physical consequences of muscle activity—heat, work, and energy expenditure. Meyerhof investigated the chemical reactions involved.
Their results linked the physical and chemical aspects of muscle metabolism. Hill’s measurements of the heat of reduction can be explained by Meyerhof’s observations of the consumption of lactic acid and oxygen. Hill himself acknowledged that Meyerhof’s biochemical work helped complete a picture that physical measurements alone could not provide.
Connection to modern metabolism
Meyerhof’s research contributed to new understanding of glycolysis, the pathway by which cells break down glucose and other sugars to produce energy.
His observations also led to the so-called Pasteur-Meyerhoff effect: respiration can inhibit the breakdown of carbohydrates through glycolysis. His work provided the first evidence that energy transformations in living cells could involve cyclic processes, an idea that became important in the development of modern intermediary metabolism.
Since then, terminology and biochemical models have changed significantly. It is now believed that muscle metabolism involves multiple pathways and energy transporters, including ATP, and is not explained simply by lactic acid.
An interesting part of Meyerhof’s scientific career is that he did not remain committed to every interpretation that arose in his early work.
The discovery of creatine phosphate in 1926 led him to question the idea that lactic acid itself was directly responsible for supplying the energy needed for muscle contraction. He subsequently revised aspects of the model that became relevant to his work.
Nobel recognition
Hill and Meyerhof gave their Nobel lectures on December 12, 1923. Hill’s lecture was called Mechanism of muscle contractionand Meyerhof was called Energy conversion in muscles.
Their work established quantitative approaches to the study of muscle metabolism by combining measurements of heat, mechanical work, oxygen consumption and chemical changes.
More than a century later, the details of muscle energy metabolism have become understood in much greater molecular detail. But Hill’s measurements of heat and energy, and Meyerhof’s work on oxygen, glycogen, and lactic acid, were important steps in establishing muscle as a system whose mechanical activity could be related to measurable chemical and thermodynamic processes.
Published – September 13, 2026 7:04 pm EST.