Date of Award
Master of Science (MS)
School of Kinesiology and Recreation
Overtraining is a widespread epidemic in collegiate cross-cross country which causes excessive fatigue and limits improvement in critical physiological measures such as maximal oxygen uptake (VO2 max), ventilatory threshold (VT), and running economy (RE). Research has suggested that overtraining can be identified by monitoring daily and weekly cardiac load (CL) as well as changes in load over time measured by an acute to chronic cardio load ratio (A:C). Assessing the relationships between these foundational aerobic athlete variables and A:C will provide important information about fitness changes over the course of a competitive season as well as potential insight into the overtraining phenomenon. PURPOSE: To determine the metabolic changes in elite endurance athletes over a cross country season and identify a relationship with cardio load and A:C. METHODS: Volunteer participants ranging from 18-23 years of age were recruited from the Illinois State University cross country team for this study. Athletes recorded heart rate data daily from each training session and attended both a pre and post season laboratory testing session. In the lab, a discontinuous maximal graded exercise test was performed consisting of 3 submaximal bouts lasting 4 minutes each separated by 1 minute of rest. After the 3rd stage and subsequent rest, a maximal ramp protocol was initiated by increasing the incline 1% each minute until volitional exhaustion. An analysis of the metabolic variables of interest was conducted in Microsoft Excel to determine change from pre to posttest as well as any interactions with cardiac load data. RESULTS: A:C tended to decrease throughout the season for most athletes with the team average gradually declining from 1.11 during the week of September 25th to 0.65 for October 30th. Top performers at the postseason championship races had the highest average A:Cs (Top male: 1.30; Top female 0.95), and worst performers for a given race tended to have the lowest relative CL in the preceding week. In the lab, there was high individual variability and few significant global changes. Average VO2 max for males increased from 66.3 mL.kg-1.min-1 during preseason testing to 67.3 mL.kg-1.min-1 for postseason (53.8 to 53.8 for females). Individual outlying VO2 max values tended to regress towards the mean, VT increased slightly for both sexes (Females: +5.1 %VO2; Males: +4.6 %VO2 max) with established long-distance runners consistently demonstrating the highest values, and RE improved moderately for all stages excluding 2 notable outliers. Top performers according to test duration typically had the best RE values for all stages (Female: 42.4, 79.3 & 86.7 %VO2 max for stages 1,2 & 3; Male: 66.1, 72.1, 83.5 %VO2 max). CONCLUSION: Data suggests that maintaining consistently high CL and A:Cs above 0.9 throughout the season may be optimal for improving race performance. Specifically, CL should not decrease significantly in the week leading up to a competition. Physiological testing confirms the importance of measuring VO2 max, VT, and RE, and monitoring changes in these values over the year could be predictive of performance or potential success at specific distances.KEYWORDS: Cardio Load, Internal Workload, VO2 max, Ventilatory Threshold, Running Economy, Endurance Running, Distance Running
Gillum, Jacob M., "The Relationship between Cardiac Load and Metabolic Changes throughout a Collegiate Cross-country Season" (2023). Theses and Dissertations. 1671.