During exercise, the oxidative system is characterized by an increase in oxygen uptake for the metabolism of energy substrates at a given exercise frequency, intensity, time, and type. The human oxidative energy system produces more energy than nonoxidative energy systems therefore, it is an essential consideration when examining sports performance ( 1). We found significant differences in time to crossover between runners and CrossFit athletes, which suggests that substrate use may be dependent on sport type. Triathletes’ percent V˙O 2max at crossover was significantly lower than rowers ( P = 0.04) and runners ( P = 0.04). Pairwise analyses revealed that runners had a significantly longer time to crossover compared with CrossFit athletes ( P = 0.009). Significant differences were observed between groups for time to crossover ( P = 0.007) and percent V˙O 2max at crossover ( P = 0.01). Times to crossover for runners, triathletes, rowers, and CrossFit athletes were 4:16 ± 0:58, 3:28 ± 1:08, 4:00 ± 1:23, and 3:01 ± 0:58 min, respectively. ResultsĪverage time to crossover for all athletes was 3:43 ± 1:12 min. Bonferroni correction procedures were used to control the family-wise error rate and maintain alpha levels at P < 0.05. A Kruskal–Wallis test was applied to determine differences between sport types for percent V˙O 2max and heart rate at crossover. A one-way ANOVA determined differences in time to crossover. Sports included running ( n = 20), triathlon ( n = 20), rowing ( n = 20), and CrossFit ( n = 17). MethodsĪ total of 77 athletes (39 women, 38 men 39.1 ± 10.4 yr of age) were measured for respiratory exchange ratio during a modified Taylor V˙O 2max treadmill test. The purpose of our study was to determine if various sports yield differences in the time to crossover and heart rate and percentage of maximal oxygen consumption (V˙O 2max) at crossover during a standardized exercise protocol. The crossover point varies in an intensity-dependent manner however, less is known about its specificity in sports with varying metabolic demands. The crossover point occurs during exercise when one transitions energy substrates from fat to carbohydrate predominance. The work cannot be changed in any way or used commercially without permission from the journal. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. 1Worldwide Sport Nutritional Supplements, Bohemia, NYĢDepartment of Integrative Biology, University of California, Berkeley, Berkeley, CAģDepartment of Health Sciences, Drexel University, Philadelphia, PAĤSchool of Behavioral and Health Sciences, Australia Catholic University, Melbourne, AUSTRALIAĥSchool of Medical and Health Sciences, Edith Cowen University, Perth, AUSTRALIAĦDepartment of Nutrition Sciences, Drexel University, Philadelphia, PAħSamson College of Health Sciences, University of the Sciences, Philadelphia, PAĨDepartment of Human Nutrition, Foods, and Exercise, Virginia Polytechnic Institute and State University, Blacksburg, VAĪddress for correspondence: Stella Lucia Volpe, Ph.D., R.D.N., ACSM-CEP, FACSM, Department of Human Nutrition, Foods, and Exercise, Virginia Polytechnic Institute and State University, 295 West Campus Drive (MC 0430), 338 Wallace Hall, Blacksburg, VA 24061 (E-mail: ).

Crossover definition in research