Elevated glucose levels after meals (postprandial hyperglycemia) and large fluctuations in post-meal sugar levels can increase the risk of developing cardiometabolic disorders not only in people with diabetes but also in healthy individuals. Indeed, impaired glucose metabolism after eating is associated with increased oxidative stress, heightened activity of proinflammatory factors, vascular dysfunction, and an increased risk of cardiovascular diseases. It’s important to note that exercise plays a significant role in improving the glycemic response after meals and, therefore, in preventing the negative effects of excessive glucose spikes. However, the relevant exercise parameters related to post-meal metabolic control are often overlooked in current physical activity recommendations for both people with diabetes and healthy individuals.
The timing of exercise relative to the previous or subsequent meal is crucial for metabolic control. Exercise after a meal appears to reduce the glycemic response to a greater extent than fasting exercise. Furthermore, proper timing of exercise can reduce the post-meal glucose peak, thereby preventing associated cardiometabolic effects. However, there is limited research on the relationship between exercise timing and glucose peak reduction in healthy individuals.
The impact of different types of exercise on the glycemic response is another important factor to consider. Both aerobic and resistance exercises effectively improve glycemic control in both fasting and post-meal situations for people with diabetes. Additionally, a combination of aerobic and resistance exercises has shown a stronger influence on long-term glucose control in type 2 diabetes patients, while no significant differences were observed in acute glycemic responses. However, there is also a lack of sufficient data on this topic.
Other parameters potentially affecting post-meal glucose levels include exercise intensity, duration, and the fragmentation of exercise through breaks. The impact of exercise intensity has been studied, and no differences in post-meal glucose levels were found between low, moderate, and high-intensity workouts. Similarly, only a few studies have assessed the effect of exercise duration on post-meal glycemic response. Likewise, there is no clear evidence regarding the impact of activity breaks performed during the first hours after eating.
The goal of the study published in the journal Medicine & Science in Sports & Exercise was to provide insight into the influence of various exercise strategies on the glycemic response after meals by systematically manipulating key exercise parameters, including timing, type, duration, and modality.
Six separate studies were conducted to evaluate the impact of each of these parameters on the glycemic response after meals, using homogeneous groups of healthy individuals to facilitate comparisons between the studies. This approach allowed researchers to study the effects of exercise itself, excluding mixed factors related to disease and medication therapy. In aggregate, the results of these six studies were intended to shed light on how to design workouts to improve the glycemic response after meals.
In Study 1, the impact of 60 minutes of brisk walking, initiated 30, 60, or 90 minutes after breakfast, on glycemic responses after breakfast and lunch was compared.
Study 2 examined the effects of 30-minute sessions of different types of exercises (aerobic exercises, strength exercises, or combined).
In Study 3, the effectiveness of 30-minute sessions of various types of aerobic exercises (walking, cycling, or elliptical training) was compared.
Study 4 evaluated the impact of 30 minutes of brisk walking performed either 45 minutes before or 15 and 30 minutes after breakfast.
Study 5 compared 30 minutes of brisk walking after meals with 45 minutes of the same.
In Study 6, the effects of a total of 30 minutes of brisk walking exercises, divided into sessions of 15, 5, or 2.5 minutes each, performed every 15 minutes, were compared.
Results: Exercise performed after, but not before, meal intake improved the glycemic response (Studies 1 and 4). The glycemic peak decreased only when exercise began 15 minutes after eating (Study 4). A similar reduction in post-meal glucose levels was observed with different types of exercises (Studies 2 and 3). Fast walking 30 and 45 minutes after meals provided a similar reduction in post-meal glucose levels (Study 5). With activity breaks, a total of 10 and 20 minutes of exercise during the first hour after eating was sufficient to effectively reduce glycemia (Study 6). This result was achieved using 2.5-minute activity breaks every 15 minutes. When this exercise break format was extended to 3 hours after eating, further improvements in the glycemic response were observed.