Changes in cytokines, leptin, and IGF-1 levels in overtrained athletes during a prolonged recovery phase: A case-control study
Joro R, Uusitalo A, DeRuisseau CK, & Stalay M. Journal of Sports Sciences. Published online 14 Dec 2016. doi: 10.1080/02640414.2016.1266379
Take Home Message: Overtrained athletes have abnormal inflammatory and anabolic responses to exercise, indicating that their body is not responding to exercise the way that it should.
Rest and recovery is an important aspect of training that can often be overlooked. When athletes or clinicians do not allow for appropriate recovery, this can lead to overtraining syndrome. Overtraining syndrome is associated with poor performance and lack of exercise tolerance. While we know clinically what the symptoms of over training are (e.g., poor performance), it remains less clear what is occurring pathophysiologically. Therefore, the authors of this prospective cohort study assessed biochemical measures of inflammation, energy metabolism, and growth factors between overtrained and control athletes, and how these athletes respond to exercise bouts. Seven overtrained athletes and 10 healthy control athletes were examined at baseline, 6 months, and 12 months. Researchers studied blood samples collected before and immediately post-exercise (maximal cycle ergometer exercise test) for certain biochemical markers indicative of inflammation, energy metabolism, or muscle growth. Researchers also assessed physiological measurements, including VO2 max, body composition, time to exhaustion, maximal heart rate, and maximal power output. During the 12 months, overtrained athletes completed a lower intensity training program aimed at recovery, while control athletes continued their normal training routines. Only 6 overtrained athletes completed the 6 month evaluation and 4 completed the 12 month session. Body fat percentage was consistently higher in overtrained athletes in comparison to control athletes. Biochemically, changes in an inflammatory mediator (interleukin-6) after exercise correlated to VO2 max changes. Overtrained athletes consistently had greater pro-inflammatory changes (i.e., interleukin-1beta) after exercise while the control athlete did not. Also, leptin, which relates to energy metabolism, was consistently lower at rest in overtrained athletes when compared with control athletes, while an anabolic marker (insulin like growth factor-1) decreased after exercise in overtrained athletes but not control athletes.
These findings are interesting because it shows that there is a pathophysiologic reason for the clinical symptoms that we are seeing among overtrained athletes. Biochemical markers may be an important objective measure to take into consideration when trying to decide how to treat an athlete. Normal responses to exercise are important for health and performance, but when an athlete is overtrained, there are abnormal responses being observed. It would be interesting to see if the overtrained athletes adhered to recovery exercise programs better, how long it would take to return to a normal status. It would also be interesting to see if recovery to a normal status would be affected by how long an athlete was in an overtrained state. While the study is limited by its small sample size and large dropout rate it still provides interesting evidence that “pushing through” training plateaus by training harder could adversely affect how our body responds to exercise. Overtrained athletes are actually achieving worse physiologic outcomes, and have biochemical profiles that are not allowing their bodies to optimally regulate inflammation and anabolic processes, and these findings may be exacerbated if the exercise was an impact based activity as opposed to a cycle test. Finding an appropriate balance between training and recovery is critical. As clinicians, we need to educate our athletes to listen to how their bodies feel. There is a physiologic reason for why they feel that way, and their body will fail to respond the way they want it to if they continue their training program.
Questions for Discussion: What are your thoughts on training cycles? Do you have any other successful clinical measures for identifying and successfully intervening in over-trained athletes?
Written by: Nicole Cattano
Reviewed by: Jeffrey Driban
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Joro, R., Uusitalo, A., DeRuisseau, K., & Atalay, M. (2016). Changes in cytokines, leptin, and IGF-1 levels in overtrained athletes during a prolonged recovery phase: A case-control study Journal of Sports Sciences, 1-8 DOI: 10.1080/02640414.2016.1266379