what is the best time to exercise for prediabetes
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What is the Best Time to Exercise for Prediabetes and Blood Sugar Control?

It’s no secret that physical exercise is a key part of reversing prediabetes and lowering your blood sugars. But, what is the best time to exercise for prediabetes? Is there an ideal time to exercise to help improve your blood sugar?

After all, finding time to exercise can be difficult. So, you probably want to use that time in the best way possible.

Fortunately, there’s been a number of research studies that examine exercise timing for prediabetes and diabetes, which we can use to better inform our exercise schedule so we get the most benefit.

But, before we dive in, who am I? And, why should you trust me? 
I’m Jon Lanman, a Registered Dietitian, and ACSM certified Clinical Exercise Physiologist, with a masters in both nutrition and exercise physiology. The goal of my blog is to translate evidence-based research into actionable guidance for people like you.

In this article, I’m going to focus on the best time to exercise for your blood sugar, but if you’re looking for more extensive exercise guidance, be sure to check out my full article on exercise for prediabetes.

The following article is meant for nutrition education. Please consult with your healthcare provider before beginning an exercise program.

Should You Exercise In the Morning or Afternoon? 

Many people prefer to exercise in the morning because it’s when they have the most free time, and fewer work and family responsibilities.

Personally, I’ve found morning exercise convenient because it wakes me up and helps energize me for the rest of the day. Knowing I’ve already accomplished my exercise goal also gives me a sense of accomplishment, and relief knowing that if something comes up with work or family, it’s not going to interfere with my exercise routine.

And, studies do confirm that people better adhere to morning exercise routines (1). So, if you’re having trouble sticking to your routine and finding time in the afternoon, it’s worth setting your alarm clock a little bit earlier, and giving it a shot. 

Studies also show that morning exercise can be good for your blood sugars. One meta-analysis (2) suggested that for those with type 2 diabetes, morning exercise when fasted could significantly improve 24-hour glucose levels, and increase insulin sensitivity for 24-48 hours after morning exercise (3). 

But, is it Better to Exercise in the Afternoon for Prediabetes?

What if you’re not a morning person, or don’t have time to exercise in the morning? Don’t worry, there are a number of studies that suggest afternoon exercise may be better for your blood sugar than morning exercise, particularly if you participate in moderate to vigorous-intensity exercise. 

One study found that moderate-to-vigorous level exercise in the afternoon or evening was associated with up to 25% reduction in insulin resistance.(4). 

The Benefits of Afternoon HIIT

HIIT training for prediabetes

HIIT stands for high intensity interval training. In a small study of men with type 2 diabetes, they split people into two groups. One group did a morning HIIT routine on stationary cycles for three days a week. The other group did the same HIIT routine in the late-afternoon. After two weeks, the participants had two weeks off, then switched groups and performed the routine for another 2 weeks (5).  

From the results of this study, they found that afternoon HIIT sessions resulted in better glucose measurements than morning HIIT sessions. Strangely, morning HIIT exercise actually increased blood sugars, while those who participated in afternoon HIIT saw lower overnight blood sugar measurements that even carried over into the following day.

What About Lower Intensity Afternoon Exercises? Are They Good Too?

Do the blood sugar benefits above only apply to HIIT training? No.

There are multiple studies that suggest better glycemic control from a variety of different types of afternoon exercise, that include lower intensity exercise regimens as well. 

For one study, people did 12 weeks of combined aerobic and resistance training for three days per week. They all did 30 minutes of bicycling at 70% of their max capacity for two days per week, and resistance exercise targeting large muscle groups for one day per week, at 60% of their max. The only difference between the groups was that one group exercised in the morning between 8:00-10:00 am and the other group exercised in the afternoon between 3:00-6:00 pm (6). 

The group who exercised in the afternoon experienced several superior benefits, including: 

  • Improved insulin sensitivity
  • More fat loss 
  • Increased exercise performance

An additional study found superior A1C improvements in men and women with type 2 diabetes who did midday exercise vs morning exercise, and they also experienced greater improvements in their cardiac fitness levels (7).

And, as already mentioned, you don’t need to exercise at a high intensity to get these benefits. Studies have shown that simply getting more walking steps later in the day could improve A1C and BMI (8).

Should You Exercise Before or After Eating to Lower Blood Sugars?

timing exercise around meals for prediabetes

So far, we’ve only discussed exercise timing in relation to time of day, morning vs afternoon. But what about timing your exercise to align closely with your meals? Is there benefit to that?

Absolutely!

Exercising before a meal or after a meal have both been shown to benefit blood sugar levels. 

Premeal exercise has been shown to lower premeal glucose levels, and increase postmeal insulin sensitivity, which helps improve overall glucose levels (9).

However, most research suggests that exercising after a meal offers better improvements in postmeal glucose levels for those with prediabetes or type 2 diabetes (10). This is because muscle contractions increase the usage of glucose already in the bloodstream (11). 

To make the most of this benefit, you could do a short bout of exercise after each meal. Walking for 15 minutes after each meal is associated with better post-dinner glucose measures, than doing one 45-minute walk earlier in the day (12).

You can think of this as a post-meal exercise snack. 

Bring the Dog Along

dogs can help you prevent diabetes

As a side note, did you know that your dog can help you prevent diabetes and help you exercise? 

People who own dogs were found to get more physical activity, have lower blood pressure, and cholesterol levels and have a lower risk for type 2 diabetes (13). Why? Maybe because Fido can be a great coach, motivating dog owners to get daily walks.

You can start exercising by simply adding a 15-30 minute dog walk after your meals. It will ensure you have a happy friend, and help reduce your risk of diabetes. Talk about a win-win. 

Finding the Perfect Time to Exercise for Prediabetes

The overall consensus is that exercise at any time, is significantly better than no exercise at all. But if you’re looking to optimize your exercise schedule, research supports the following: 

  • Exercise in the morning if you’re having trouble sticking to a routine
  • Do moderate to vigorous intensity exercise in the afternoon instead of the morning
  • Increase your daily step count and physical activity throughout the day
  • Take a 15-30 minute walk after each meal

If you’re just starting an exercise routine, don’t overthink it. Start by making a small improvement, with the goal of reaching the recommended minimum of 30 minutes of moderate intensity exercise per day. 

Start by making a small improvement. That could mean taking three 10-minute walks per day, or getting 7,000-10,000 steps per day.

You don’t need to have a perfect exercise routine in order to get the benefits. Start with what’s doable for you now, and do it consistently. Something is better than nothing. And, the research proves that.

For a more in-depth look at exercise recommendations, check out my article on exercising for prediabetes.

References:

  1. Consistent Morning Exercise May Be Beneficial For Individuals with Obesity 
  2. Acute and Chronic Effects of Exercise on Continuous Glucose Monitoring Outcomes in Type 2 Diabetes: A Meta-Analysis 
  3. Interactions between insulin and exercise
  4. Timing of physical activity in relation to liver fat content and insulin resistance
  5. Afternoon exercise is more efficacious than morning exercise at improving blood glucose levels in individuals with type 2 diabetes: a randomised crossover trial
  6. Exercise training elicits superior metabolic effects when performed in the afternoon compared to morning in metabolically compromised humans
  7. Morning versus afternoon physical activity and health-related outcomes in individuals with type 2 diabetes
  8. Patterns of Timing and Intensity of Physical Activity and HbA1c Levels in Hispanic/Latino Adults With or at Risk of Type 2 Diabetes
  9. One Bout of Exercise Alters Free-Living Postprandial Glycemia in Type 2 Diabetes
  10. One Bout of Exercise Alters Free-Living Postprandial Glycemia in Type 2 Diabetes
  11. Exercise after You Eat: Hitting the Postprandial Glucose Target
  12. Three 15-min Bouts of Moderate Postmeal Walking Significantly Improves 24-h Glycemic Control in Older People at Risk for Impaired Glucose Tolerance
  13. Dog walking is associated with a favorable risk profile independent of moderate to high volume of physical activity 

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