You hit 10,000 steps today. Your fitness tracker congratulates you.
But what happened to your body during the 8 hours you spent sitting?
Your step count stayed at zero during those hours. Your soleus — a muscle that acts like a second heart — was largely inactive.
Steps measure walking. They do not measure what happens while you sit.
Short answer: Steps and soleus activation measure different things. Steps tell you how much you walked. Soleus activation tells you something about what happened to your body during the hours you spent sitting. Neither is more important — they answer different questions about your day.
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Steps are a useful metric. They encourage walking, which is good for cardiovascular health, weight management, and overall activity. But steps have a blind spot: they only measure activity when you are moving.
When you sit for 8 to 10 hours at a desk, your step count stays at zero. Your fitness tracker shows no activity. But your body is still working — or not working, in some ways. The soleus muscle, which is active when you stand or walk, becomes largely inactive when you sit.
SHB stands for Soleus Heart Beat. It is a metric created by 2HEART to count the number of soleus activations during a seated session. A higher SHB means your second heart was more active during the hours you spent sitting.
This is not a replacement for steps. It is a different question: what happened to your body during the hours you were not walking?
Learn more about SHB and Soleus Health →
Most fitness trackers are designed to measure what you do when you are active. They count steps, calories, heart rate, and sleep. They do not measure what happens when you are still — even though most people spend most of their waking hours seated.
This is not a criticism of fitness trackers. They were designed to measure activity, not inactivity. But the absence of data during sitting hours may create a blind spot in how we think about daily movement.
Read more about the soleus muscle →
In the Hamilton study, participants performing a specific seated soleus activation protocol experienced a 52% reduction in post-meal glucose excursion compared to uninterrupted sitting. The Houghton study found that people with reduced calf muscle pump function were twice as likely to experience serious health events over time.
These findings suggest that seated movement — which steps do not measure — may matter for health. However, more research is needed, and individual results may vary.
Read the Hamilton study summary →
No. Steps are still a useful metric for walking activity. But if you spend 8 to 10 hours sitting each day, steps alone do not tell the full story. They do not tell you what happened to your body during the hours you were seated.
This is why new metrics — like SHB — are being explored. Not to replace steps, but to answer a different question.
Steps measure walking. Soleus activation measures something different. That is why we created Soleus Health — a new way to think about movement during the hours you spend sitting. Explore sitting physiology →
Compare with: Does walking undo the effects of sitting? →
Educational purpose only. This information is not medical advice. Consult your doctor before starting any new movement routine.