Exercise is good for you. There are many ways by which exercise favorably modifies health. One way is through a chemical known as interleukin-6, usually abbreviated as IL-6. During and following exercise, skeletal muscles release IL-6 into the blood. It is then transported throughout the body where it can have positive effects. For example, the release of IL-6 during and following acute bouts of exercise is thought to contribute to a decrease in the fat that accumulates around the waist.
The amount of IL-6 released from skeletal muscles during and following exercise appears to be determined by the duration and the intensity of the exercise; generally, more is better. Unfortunately, for a variety reasons, many people are unwilling or unable to participate in long-duration exercise or exercise characterized by sustained high-intensities. These people may be missing out on the IL-6 mediated health benefits associated with exercise.
Enter caffeine.
Caffeine is one of the active ingredients in coffee. According to previous research from other laboratories, caffeine increases the amount of IL-6 released into the blood following long-duration and high-intensity exercise. However, almost all of this research was completed by studying males only.
In our research project, published in the June 2023 issue of Medicine & Science in Sports & Exercise®, we studied both males and females to address the question as to whether caffeine would increase the amount of IL-6 in the blood after 30 minutes of moderate-intensity exercise. That is, we would study the interaction between caffeine and a common workout duration at an intensity that many people would find manageable.
Ten males and ten females, aged 25 ±7 years, participated in the study. In general, these study participants were habitual exercisers who were considered recreationally active. Most were of average cardiorespiratory fitness for their age. Following initial screening and baseline testing, each of the participants returned to the lab for two experimental visits, separated by at least a week. Each visit began with ingesting either a capsule containing an ingredient that has no physiological effect (a placebo), or caffeine. The caffeine dose was individualized and based on body mass (6 mg of caffeine per kg body mass). For most participants, this would be the equivalent of two to three strong cups of drip coffee. One hour later, each participant rode an exercise cycle for 30-minutes at a moderate intensity (approximately 60% of their maximal aerobic capacity).
When we looked at all the results together, we found that caffeine increased the amount of IL-6 in the blood after exercise. However, when we separated the results into males and females, we found that caffeine only increased the IL-6 response in the males.
At this time, we do not know why the males and females responded differently to caffeine and exercise; this question could be addressed in future research. The implication of our current study is that caffeine may increase the IL-6 mediated health benefits of 30 minutes of moderate-intensity exercise in males.
Related CEC Courses:
Industry Presented Webinar: The Female Athlete (1 CEC)
Is it Science or Sensationalism? Reading Through the Headlines to Fuel Optimal Performance (3 CECs)
Kieran Abbotts obtained his M.S. in health and exercise science from Colorado State University. He is currently a Ph.D. student in the Department of Human Physiology at the University of Oregon. His research focuses on the factors underlying how environmental and physical stressors impact human health and physiology. He is a member of ACSM.
Christopher Bell, PhD, is an associate professor in the Department of Health and Exercise Science at Colorado State University. Together with his graduate students, he addresses a variety of research questions pertaining to human health, physiological function, and exercise performance.
Viewpoints presented in ACSM Bulletin commentaries reflect opinions of the authors and do not necessarily represent positions or policies of ACSM. Active Voice authors who have received financial or other considerations from a commercial entity associated with their topic must disclose such relationships at the time they accept an invitation to write for the ACSM Bulletin.
