McMaster University

Child Health & Exercise
Medicine Program

Scope of Search

The ExID Study

Determining the effects of Exercise Intensity and Duration on NK Cell response at distinct stages of growth and development

Many studies in adults have shown that regular exercise can improve a person’s ability to fight off invaders such as infections and cancers. This is primarily because exercise can help improve Natural Killer (NK) cells, which are a type of immune cell in the body. Surprisingly, we don’t know much about how these cells act in response to exercise in children. As children grow and mature, their bodies change and with that, their immune system matures as well. The goal of the study is to understand the relationship between exercise and the body’s ability to protect itself at different stages of development.


To do this, we are going to answer the following questions:

  • Does the intensity and duration of exercise impact how NK cells respond?

  • Is there a difference in how NK cells respond to exercise between children and adolescents?

  • Does the NK cell response to exercise differ between boys and girls?

What does this study involve?

This study involves five separate exercise visits to the Child Health and Exercise Medicine Lab. During the first visit, we will measure the participant’s fitness level. At the end of the visit, will give the participant a small device called an accelerometer (like a Fitbit but worn around the waist) to measure their physical activity over the next week. At visits 2-5, participants will exercise for 30 minutes. We will take blood samples before and after exercise (four in total).


Who is eligible to participate?

We are looking for children 8 to 11 years old and adolescents 15 to 18 years old to participate. Participants must not have a diagnosed medical condition.  


Who do I contact if I want to learn more?

If you have questions or want to learn more about this study, please contact Inna by e-mail at or call 905-521-2100 ext. 77566.


This study is funded by a Discovery Grant to Dr. Joyce Obeid from the Natural Sciences and Engineering Research Council of Canada