Blood glucose plays a central role in how your body stays fueled – both in everyday activity and during challenging F45 workouts.
But because glucose levels continually respond to food, exercise, sleep, and stress, understanding what influences your individual patterns can help you make more informed choices around training, nutrition, and recovery.
A continuous glucose monitor (CGM) like Lingo is a powerful everyday wearable designed to give you a real-time view of your glucose. Minute-by-minute data can help you see patterns and identify habits that keep your glucose in a healthy range more often.
Below, we’ll explore what blood glucose is, how different types of exercise can raise or lower it, and when a glucose spike may be worth paying attention to. We’ll also unpack the benefits of resistance training for metabolic health, and how CGM insights can help you personalize your approach to performance, recovery and long-term wellness.
What is blood glucose?
Glucose – also known as blood sugar or blood glucose – is a type of sugar the body relies upon as a primary source of energy. Glucose powers the brain and muscles1, and its main source is the food we eat – primarily carbohydrates such as fruits, vegetables, and grains.
Glucose levels ebb and flow across the day, responding to factors such as food, sleep, and movement – as well as stress and burnout2. Day to day, our glucose levels impact our mood, energy, focus, and hunger. Over time, glucose links to our risk of type 2 diabetes and can impact heart health. This is why understanding your biology – diving deeper into your glucose levels and the wider patterns around your health they reveal – is so important.
How does exercise affect blood glucose?
Muscles are powered by glucose – and are also incredibly effective at putting this fuel to work. Muscles absorb over 80% of the glucose that circulates after a meal and nearly all glucose that’s used to fuel exercise.
Whether glucose is cleared from the bloodstream and burned for energy or stored as glycogen, muscle mass and movement are critical for healthy glucose1,2,3,4,10. This relationship between exercise and blood sugar also continues in the hours after your workout – so let’s take a closer look.
Does exercise lower blood sugar?
Yes, exercise can lower blood sugar by helping working muscles take up glucose from the bloodstream and use it for energy. This is particularly common during lower-intensity exercise, F45 cardio workouts, and endurance sessions2.
Moving shortly after a meal can also help moderate the rise in glucose that follows eating. As your muscles draw on the energy you have just consumed, glucose is directed out of the bloodstream and into the muscles, which may reduce the size of a spike or cause a short-term drop before the body begins using its stored fuel.
Does exercise raise blood sugar?
Yes, it can. HIIT and speed sessions may temporarily increase glucose because adrenaline prompts the liver to release stored glucose1,2. This connection between HIIT and blood sugar is a normal way for the body to make fast energy available to working muscles.
To maintain your intensity and avoid “hitting the wall,” you may need mid-workout fuel such as gels, chews or sports drinks. Real-time CGM data can help you understand your personal glucose response and identify how much and what type of fuel you may need before and during a workout to stay sharp and maximize performance.
What is a glucose spike, and should you worry about it?
A glucose spike is a rapid rise in blood sugar levels, most often occurring within one to two hours after eating or drinking carbohydrates.
As glucose enters the bloodstream, the body releases insulin, which helps move glucose into cells to be used for energy or stored for later. This process often causes glucose levels to fall again after the initial rise.
Glucose fluctuations are normal – as are glucose spikes. Your glucose is constantly responding to food, exercise, sleep, stress, and other factors. A CGM simply makes these changes visible, allowing you to see how your body responds from meal to meal and day to day. It’s not unusual for the same meal to produce a different response on different days – or for your response to differ completely from someone else eating the same foods.
For active individuals, a glucose spike after exercise – or temporarily higher blood sugar after a workout – is often expected. Exercise can trigger a stress response and the release of stored glucose to fuel working muscles, especially during higher-intensity training. This is another reason the relationship between exercise and blood sugar is not always as simple as glucose moving in one direction.
Outside of exercise, frequent and significant glucose spikes are worth paying attention to. Over time, repeated large fluctuations may indicate that your body is working harder to maintain healthy glucose control, and they may be associated with increased metabolic health risks. Understanding what drives your glucose response can help you make informed food and lifestyle choices that support both daily energy and long-term health.
The good news is that there are simple strategies that can help moderate glucose spikes:
- Give carbs company: Pair carbohydrates with protein, fiber, and healthy fats to slow digestion and absorption.
- Food order matters: Start meals with non-starchy vegetables, followed by protein and healthy fats.
- Mindful carbs: Prioritize high-quality carbohydrate sources such as fruit, legumes, and whole grains.
- Move more: Add a short walk after a meal to help your body use glucose more effectively.
Rather than trying to eliminate every glucose spike, focus on understanding your personal patterns and building meals and habits that support healthy glucose responses over time.
What should you eat before and after a session to keep your glucose stable?
What you eat and drink before, during, and after F45 sweat sessions impacts performance and powers the task ahead of you.
- Before: Good options for a pre-workout meal include overnight oats with protein powder, berries, and seeds, or Greek yogurt with fruit and granola. Focus on quality carbohydrates that provide sustained energy, rather than relying on simple sugars.
- During: Mid-workout fueling is most beneficial for sessions lasting longer than 60 minutes, or when starting under-fueled or fasted. Choose easy-to-digest options providing 30+ grams of carbohydrates, such as sports drinks, chews, or dried fruit.
- After: Post-workout recovery starts with replacing fluids and electrolytes lost through sweat. Then, within about an hour after training, aim for 15 to 30 grams of protein plus one to two servings of quality carbohydrates (such as fruit, ancient grains, or sweet potatoes). This combination helps support muscle repair, replenish glycogen stores, and prepare your body to go again – without unnecessary blood sugar spikes.
Plus, because the relationship between exercise and blood sugar continues after your session ends, it’s important to refuel adequately. Post-workout insulin sensitivity remains elevated for up to 48 hours after exercise4, so pay attention to your CGM glucose data to make sure you’re adequately replenishing energy stores and not dipping too low.
Dive deeper into what to eat before – and after – a workout with our dedicated guide, or brush up on exactly how much protein you need.
Can resistance training reduce prediabetes risk?
It can! Regular exercise is one of the most effective ways to reduce the risk of prediabetes and type 2 diabetes.
Prediabetes occurs when blood glucose levels are higher than normal, but not yet high enough for a diagnosis of type 2 diabetes. The CDC reports that over 115 million American adults live with prediabetes, equivalent to more than two in five U.S. adults – yet eight out of 10 don’t know they have it.
Prediabetes increases the risk of developing type 2 diabetes, heart disease, and stroke. The good news is that, according to the CDC, prediabetes can often be prevented – or even reversed – through lifestyle changes. CDC data has shown that losing just 5 to 10% of body weight and exercising regularly can cut the risk of progressing to type 2 diabetes by up to 50%2. This is why exercise for prediabetes commonly combines aerobic activity with resistance training to support healthier glucose regulation.
Research shows that regular resistance workouts can reduce type 2 diabetes risk by approximately 30 to 60%, with greater benefits associated with higher and sustained activity levels3,8. Resistance training plays a key role because muscle acts as a major site for glucose uptake. Building and maintaining muscle improves insulin sensitivity and helps the body use glucose more effectively2,3. This connection between resistance training and blood sugar makes strength-based exercise especially valuable for metabolic health.
What’s more, workouts that pair strength training with aerobic exercise may provide even greater metabolic benefits than either approach alone3,8. F45’s hybrid workouts – which mix strength, cardio, and functional training – incorporate the types of exercise shown to support healthy glucose metabolism.
Keen to understand your personal risk? Try Lingo’s Prediabetes Risk Quiz today.
What is a CGM, and how can it help fuel your workouts?
Because prediabetes often develops without obvious symptoms, understanding how your body responds to food, exercise, stress, and sleep can be a valuable starting point.
One way to build that awareness is by using a continuous glucose monitor (CGM). A CGM is a wearable device that tracks glucose levels around the clock and sends real-time data to a smartphone app. Unlike a traditional finger-prick blood glucose test, which provides a single measurement at one moment in time, a CGM uses a sensor worn on the back of the upper arm to continuously measure glucose in the interstitial fluid – the fluid surrounding your cells – and stream this data to a smartphone app2.
Rather than relying on guesswork – or on single, isolated measurements – you can identify the behaviors that support steadier energy, better recovery, and healthier glucose regulation in real time. Although CGM readings can lag behind blood glucose by about three to five minutes2, they provide continuous feedback and a fuller picture of your glucose metrics that can help you identify patterns and optimize workout fueling strategies.
Research shows that athletes can experience significant variability in glucose responses depending on their training and nutrition habits9. By seeing how your body responds to different foods and workouts, you can make adjustments that support a sustainable fitness routine that prioritizes performance, recovery, and overall metabolic health.
As you gather data, focus on small, sustainable changes. The goal is progress over perfection – using these insights to better understand your body and make informed decisions that support performance, rest, and strong long-term health outcomes.
Remember – small insights can lead to meaningful changes over time!2,9
Ready to understand how your habits shape your glucose? Explore Lingo to uncover your personal patterns and make more informed choices around nutrition, training, and recovery.
1 Lingo Blog: Exercise and your glucose. https://www.hellolingo.com/blog/exercise-and-glucose-does-lower-blood-sugar
2 Lingo Blog: Effect of exercise on glucose levels. https://www.hellolingo.com/blog/exercise-flatten-glucose-curve
3 Bird SR, Hawley JA. BMJ Open Sport Exerc Med. 2017.
4 Cartee GD. J Physiol. 2018. PMID: 30394533.
5 Stocks B & Zierath JR. Endocrine Reviews. 2021.
6 Bae JH et al. J Diabetes Investig. 2018. PMID: 29502350.
7 Giuntini EB et al. Foods. 2022.
8 Feng J et al. Front Endocrinol. 2024. PMID: 38978627.
9 Bowler AM et al. J Diabetes Sci Technol. 2024. PMID: 38726672.
10 Merz KE, Thurmond DC. Role of Skeletal Muscle in Insulin Resistance and Glucose Uptake. Compr Physiol. 2020 Jul 8;10(3):785-809. doi: 10.1002/cphy.c190029. PMID: 32940941
