Active Voice: Is Kenyan Running Success an Attribute of Ventilatory Capacity?
By Glen E. Foster, Ph.D. and A. William Sheel, Ph.D.
Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM.
Dr. Foster is an Assistant Professor in the School of Health and Exercise Sciences at the University of British Columbia – Okanagan. His primary research activities relate to cardiopulmonary adaptations to physiological stressors.
Dr. Sheel is a Professor in the School of Kinesiology at the University of British Columbia – Vancouver. His principle research areas relate to respiratory and exercise physiology. Dr. Sheel also is a member of ACSM.
This commentary presents Dr. Foster’s and Dr. Sheel’s views on the topic of a research article which they and their colleagues published in the April 2014 issue of Medicine and Science in Sports and Exercise® (MSSE).
It is commonly believed that the capacity of the normal lung is “over-built” and exceeds the demand for pulmonary O2 transport in the healthy, exercising human. However, in some highly fit endurance athletes, the pulmonary system appears underbuilt relative to the demand for maximal O2 transport. For example, work from our lab and other labs have shown that many highly trained endurance athletes experience pulmonary limitations that can contribute to diminished exercise performance. For example, low amounts of O2 in arterial blood, a high work of breathing and reaching the ventilatory capacity have each been shown to be pulmonary system limitations and thus each can have consequences to maximal O2 uptake and exercise performance.
Runners from Kenya have dominated international running events for the past four decades, including events ranging from the 800m to the marathon. Determining the secret to their success has eluded researchers thus far. In our recent MSSE study, we sought to determine if the success of highly trained Kenyan runners from the Rift Valley could be attributed to improved pulmonary capacity during exercise. To test this hypothesis, we travelled to Kenya, set up a small exercise physiology laboratory, and recruited runners from the Rift Valley. Athletes were instrumented with arterial and esophageal catheters to make it possible to determine their arterial O2 content and the work of breathing. Athletes breathed through a mouthpiece such that we could measure airflow and the exchange of pulmonary gases. Collectively, this made it possible to assess pulmonary limitations during treadmill running to volitional fatigue.
We found that pulmonary system limitations were present in Kenyan runners in the form of exercise-induced arterial hypoxemia, expiratory flow limitation and high levels of respiratory muscle work. Our findings suggest that the Kenyan runners do not possess a pulmonary system that provides any sort of physiological advantage. However, it is important to understand that many other aspects of O2 delivery and exercise performance have yet to be studied in Kenyan athletes. For example, to our knowledge, no studies of the central hemodynamic changes that accompany exercise have yet been made. Our understanding of elite athletic performance is further complicated by motivational and sociological factors, which are well known to play important roles.