What your bloodwork can tell you about your fitness

This article is general information, not medical advice. Always go over your results with your doctor.

You don't need to memorize every marker. Almost every number on a standard panel answers one of four questions about your body. Once you know which question a number answers, what it means starts to make sense.

1. Is your body handling fuel well?

What to look at: fasting insulin, glucose, A1C, and triglycerides.

When you eat, glucose comes into your blood. Insulin works like a key that lets your muscles and liver take it in. If those tissues stop responding well, your body makes more insulin to get the same job done. That's why insulin often rises years before glucose does. Your glucose can look fine because insulin is working overtime. A large study that followed people for years found exactly this pattern: insulin sensitivity dropped well before blood sugar climbed (Tabák et al., The Lancet, 2009).

Triglycerides tell a related story. When your liver is dealing with more fuel than it needs, it packs the extra into fat and sends it into your blood.

What helps: muscle is the biggest place glucose can go (DeFronzo and Tripathy, Diabetes Care, 2009), and working muscle pulls glucose in even with less insulin (Richter and Hargreaves, Physiological Reviews, 2013). So training regularly, walking more, and taking a short walk after meals all give glucose somewhere to go. Light walking breaks lower blood sugar and insulin after a meal compared with sitting (Buffey et al., Sports Medicine, 2022). Building muscle makes that storage space bigger. Losing extra fat, especially around your waist, usually helps too.

The goal isn't burning calories. It's getting your body to need less insulin.

2. Is something already using up your recovery?

What to look at: hs-CRP, with cortisol for context.

CRP is a signal from your liver that there's inflammation somewhere in your body. Hard training causes some on purpose. That's part of how you get stronger. But poor sleep, ongoing stress, extra body fat, and getting sick cause it too. Short or broken sleep is linked to higher CRP (Irwin et al., Biological Psychiatry, 2016).

Think of recovery as a budget. Your training spends some of it. So does everything else in your life.

If your CRP is already high, your body is spending recovery on things that aren't your workouts. Adding more training on top of that can stall your progress instead of speeding it up. So I usually look at sleep first, because that's where most recovery happens, and we may pull back on training volume for a while. Cortisol adds context, but one morning reading doesn't say much on its own.

3. Does your body have what it needs to rebuild?

What to look at: ferritin and hemoglobin, testosterone, free T3, and vitamin D.

Hemoglobin carries oxygen in your blood, and ferritin is the iron your body stores to make it. When iron runs low, less oxygen gets to working muscle. Tiredness and a drop in how hard you can work are common signs (Pasricha et al., The Lancet, 2021). Hard conditioning can feel brutal even when everything else is right. If your iron looks low, that's a conversation for your doctor. Don't start iron supplements on your own.

Testosterone and free T3, a thyroid hormone, tell you whether your body is in building mode or holding back. If you're stressed, short on sleep, and eating too little, these can drift down. When that happens, sleep, stress, and food come before a harder diet, because your body has already turned the dial down.

You can't train your way past missing raw materials.

4. How are your heart numbers?

What to look at: LDL, HDL, ApoB, triglycerides, and blood pressure.

LDL cholesterol is often called the "bad" cholesterol. Higher levels are linked to a higher risk of heart disease. HDL is often called the "good" cholesterol. ApoB counts the particles that carry cholesterol through your blood, and many doctors now look at it alongside LDL. Blood pressure isn't part of a blood test, but it's usually checked at the same visit, and it matters just as much.

Read them together

No single number decides anything. A marker that looks off on its own can make sense next to the others, or next to how you've been sleeping, eating, and feeling. That's why I read your panel as a whole, and against how you're actually doing in your training.

How habits can move these numbers

For many people, regular exercise, better eating, better sleep, and losing extra body fat can improve some of these numbers. Not everyone responds the same way. Genes play a big role, and some people need medication no matter how well they live. That's a call for your doctor.

I've seen real changes with my clients. Aaron's LDL dropped 26 points and his triglycerides dropped 15 points in four months while he lost 26 pounds. Michael P.'s blood pressure came back to normal in eight months.

What about your liver and kidney numbers?

Your panel also comes with a safety layer: kidney values, liver enzymes, and blood counts. I read them, but I don't coach off them. They have one job. They tell us whether anything needs your doctor before we push training. That call always belongs to your physician, not to me.

One thing worth knowing: training itself can move these numbers. In one study, a single hard weightlifting session raised the liver enzymes ALT and AST in healthy men for a week or more. Carrying more muscle raises creatinine, which can make a kidney estimate look worse than it is. The National Institute of Diabetes and Digestive and Kidney Diseases notes that creatinine-based kidney estimates can be off for people with a lot of muscle.

So a flag after a heavy training block isn't automatically bad news. Often the next step is a retest after some time away from heavy lifting. Your doctor makes that call. I'll help you get ready for that conversation, including what your training looked like the week of the draw.

Labs are a snapshot. Between draws, I watch how you sleep and how fast you bounce back after hard sessions.

How I use your labs in coaching

When you share your results with me, we go over them together. I help you understand what they mean for your training, food, sleep, and stress. Then we set goals that match, and your next panel shows us whether the plan is working. Your doctor decides how often you get tested and makes every medical decision. If something needs medical attention, I tell you and send you back to your physician.

I'm a coach, not a doctor, and this isn't medical care. Bloodwork is included for clients who commit to six months. On shorter programs, labs are billed at cost.

Where to start

Pull up your last lab results and sort each number into one of the four questions. If you want help turning them into a plan, read what executive health coaching includes or see how online coaching works.