(7) THE USE OF A FORMULA TO PREDICT HEART RATE AS A TOOL FOR DAILY MONITORING OF DIVISION I CROSS COUNTRY RUNNERS

Purpose: Daily monitoring of athlete fitness or readiness to perform typically consists of a combination of internal (e.g. heart rate, rate of perceived exertion) and external (e.g. distance covered, speed) loads. The purpose of this study is to assess whether a formula that predicts the internal load (heart rate) from a given external load (speed of movement) can be used to detect changes in athlete fitness over time. Methods: Ten NCAA Division I cross-country runners, 5 men (age: 21.5±3.1 years; height: 182.9±3.5 cm; weight: 64.9±5.0 kg; VO₂ max: 56.9±6.5 mL∙kg∙min^-1) and 5 women (age: 19.2±1.8 years; height: 170.5±8.1 cm; weight: 59.7±7.4 kg; VO₂ max: 53.6±3.6 mL∙kg∙min^-1) participated in the study. An incremental treadmill test was performed to volitional failure using a metabolic cart while measuring oxygen consumption, heart rate and rate of perceived exertion at each stage before (PRE) and after (POST) a 6-week training period. To produce a prediction formula, heart rate and running speed were plotted on a graph. The slope and intercept of the line were calculated for each athlete. The equation for each athlete’s line would then be applied to their running speed that was measured during their regularly scheduled workouts using Global Positioning Software (GPS) technology to predict their heart rate. Predicted heart rates were then compared to measured heart rates (∆HR), where a reduction in measured heart rate compared to predicted heart rate would be suggestive of an improvement in fitness or readiness. Following the training period, the incremental treadmill test was repeated. Results: The athletes demonstrated a statistically significant increase in VO₂ max (PRE: 55.5±5.4 mL∙kg∙min^-1 vs. POST: 57.3±4.6 mL∙kg∙min^-1, p=0.02). The athletes saw a concomitant reduction in ∆HR over the course of the training period when comparing average workouts from Week 1 to Week 5 (Week 1: -8.0±6.0 bpm vs Week 5: -12.9±8.4 bpm, p=0.016) and Week 1 to Week 6 (Week 1: -8.0±6.0 bpm vs Week 6: -15.0±6.8 bpm, p=0.002). Conclusions: Over the course of a 6-week training period, athletes demonstrated an increase in VO₂ max which was associated with reductions in measured heart rate when compared to the predicted heart rate. These data suggest that ∆HR is a valid tool for measuring changes in fitness or readiness. Practical Applications: The use of a simple formula to predict heart rate can be compared to measured heart rate during training to assess fitness changes and athlete readiness on a day-to-day basis. This allows for continuous feedback on athlete fitness without having to rely on organized testing, which takes time away from regularly scheduled workouts. Acknowledgements: None