Effects of Running an Ultramarathon on Cardiac, Hematologic, and Metabolic Biomarkers

Serum biomarkers fluctuate as a result of running marathons, but their changes during ultramarathons have not been adequately studied. We collected blood samples from 20 participants before and 21 participants after the 161-km ultramarathon in Leadville, Colorado in August 2013. Using a portable analyzer, we measured cardiac troponin I (cTnl), hematologic, and metabolic biomarkers. Out of 10 runners for whom we collected both pre- and post-race samples, 8 were able to successfully complete the race. Mean cTnl increased from 0.001 to 0.047 ng/mL (p=0.005). Mean sodium decreased from 141 to 138 mmol/L (p <0.01). However, all runners had a sodium of ≥135 mmol/L post-race (reference range 138-146 mmol/L). Mean creatinine increased from 0.93 to 1.17 mg/dL (p <0.05). Only one out of 10 runners had an abnormal creatinine level of 1.8 mg/dL post-race (reference range 0.6-1.3 mg/dL). The other parameters did not reach statistical significance. Analyzing the samples from 21 runners after the race revealed that runners who finished the race in faster time had higher cTnl levels compared to those who finished the race close to the 30-hour cut-off finish time (P=0.005). Running an ultramarathon caused significant changes in cardiac and metabolic parameters. Ultramarathon running intensity and finish time may have effects on post-race cTnl level.

Epidemiology of stress fracture injuries among US high school athletes, 2005-2006 through 2012-2013

BACKGROUND

High school athletes in the United States sustain millions of injuries annually, approximately 10% of which are fractures. However, there is no clear estimate of the number of stress fractures sustained by high school athletes annually despite reports that stress fractures account for 0.7% to 20% of injuries seen in sports medicine clinics. This suggests a high utilization of resources for a potentially preventable injury. In addition, stress fractures have been associated with low energy availability and disordered eating in young athletes, highlighting the importance of early recognition and intervention.

PURPOSE

To investigate stress fracture rates and patterns in a large national sample of US high school athletes.

STUDY DESIGN

Descriptive epidemiologic study.

METHODS

Data from High School RIO (Reporting Information Online), a national sports injury surveillance study, were analyzed to describe rates and patterns of stress fracture injury sustained from 2005-2006 through 2012-2013, across sports and by sex.

RESULTS

From 2005-2006 through 2012-2013, a total of 51,773 injuries were sustained during 25,268,873 athlete-exposures, of which 389 (0.8%) were stress fractures, resulting in an overall stress fracture rate of 1.54 per 100,000 athlete-exposures. Rates per 100,000 athlete-exposures were highest in girls' cross country (10.62), girls' gymnastics (7.43), and boys' cross country (5.42). In sex-comparable sports, girls sustained more stress fractures (63.3%) than did boys (36.7%) and had higher rates of stress fracture (2.22 vs 1.27; rate ratio, 1.75; 95% CI, 1.38-2.23). The most commonly injured sites were the lower leg (40.3% of all stress fractures), foot (34.9%), and lower back/lumbar spine/pelvis (15.2%). Management was nonsurgical in 98.7% of the cases, and 65.3% of injuries resulted in ≥3 weeks of time loss, medical disqualification, or an end to the season before athletes could return to play.

CONCLUSION

Although a rare injury, stress fractures cause considerable morbidity for high school athletes of both sexes. Future research should evaluate risks of stress fractures to drive development of targeted prevention efforts.