Most people spend several hours per day seated at work, during commutes, while eating, and during leisure time.
The Hamilton study suggests that a muscle representing roughly 1% of body mass may significantly influence post-meal blood sugar when activated appropriately during sitting.
This raises a broader question: Can sitting health be improved by restoring activity to muscles that normally become inactive during prolonged sitting?
For the millions of people with diabetes, prediabetes, or simply concerns about their metabolic health, this research opens a new line of thinking about what happens to the body during the hours we spend seated.
The Hamilton study (2022) from the University of Houston investigated whether sustained soleus activation during seated time could influence metabolic outcomes. Participants performed seated soleus contractions while researchers measured post-meal blood sugar and insulin responses.
The key finding: sustained soleus activation produced a 52% reduction in post-meal glucose spikes and a 60% reduction in insulin requirement compared to uninterrupted sitting. In other words, activating the soleus during sitting significantly lowered blood sugar after eating. The soleus, comprising approximately 1% of body mass, became the dominant glucose-consuming tissue during the session.
Important context: This study used a specialised laboratory device to induce sustained soleus contraction. The 52% reduction was measured in that specific context. Casual heel raises may not produce identical results.
Participants remained seated for extended periods while performing intermittent soleus contractions. The study used a crossover design, meaning each participant served as their own control, comparing periods of soleus activation against periods of uninterrupted sitting.
Blood samples were taken at regular intervals to measure post-meal blood sugar and insulin levels following a standardized meal. The researchers also measured whole-body fuel utilization to determine which tissues were consuming energy during the soleus activation sessions.
The soleus muscle is composed of approximately 70-80% slow-twitch Type I muscle fibres, one of the highest proportions in the human body. Unlike most muscles that rely primarily on stored glycogen for energy, the soleus can draw fuel directly from circulating blood, including glucose and lipids, during low-intensity activity.
This unusual metabolic characteristic means the soleus can consume significant amounts of post-meal blood sugar when activated, even during seated, low-intensity activity. The Hamilton study quantified this effect, showing that the soleus became the dominant glucose-consuming tissue during the seated activation sessions.
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The Hamilton study established the metabolic case for soleus activation during sitting. It demonstrated that a small muscle, when activated appropriately, can meaningfully influence how the body processes post-meal blood sugar.
2HEART is being developed to make soleus activation practical during real-world seated work. While the Hamilton study used specialized equipment, 2HEART aims to bring the same physiological principle to desk workers, remote professionals, and anyone who sits for extended hours.
2HEART did not conduct this study. We cite it because it explores the same problem we are working on: what happens to the human body during prolonged sitting, and what role the soleus muscle may play in addressing it.
Read the original University of Houston research →
Research summary disclaimer. This page summarizes independent peer-reviewed research. 2HEART did not conduct this study. The summary is provided for educational purposes. The findings do not constitute validation of 2HEART or its intended outcomes.