The Reliability And Validity Of The Heart Rate Monitor Component Of A Sports Bra

Heart rate monitors are commonly used in sports with a large aerobic emphasis to monitor exercise intensity and are one example of the wearable technology utilized by practitioners to monitor athlete training characteristics. The combination of global positioning technology and heart rate monitors has enhanced utility of wearable technology in sport. However, it is important to assess the reliability and validity of wearable technology prior to relying on it for monitoring athlete workload. PURPOSE: The purpose of the study was to assess the reliability and validity of a sports bra heart rate monitor in female athletes. METHODS: A total of 27 division I female field hockey (n = 17) and soccer (n = 10) were recruited. Participants performed two VO2max tests while wearing the sports bra heart rate monitor and a single lead EKG to obtain maximum and average heart rate values for each test stage. Anthropometrics (height, weight) of the participants were collected. The test consisted of four stages that lasted three minutes each. During the first stage the participant was supine for resting conditions. In stage two the participant performed walking at 3.1 mph on the treadmill. Stage three was 6.1 mph, and stage four was 7.8 mph. At the end of stage four the grade of the treadmill increased by 3% every minute until volitional exhaustion. Intra-device reliability was assessed by intraclass correlation coefficient (ICC). Validity was assessed through Pearson correlation and Bland-Altman test. RESULTS: Overall, the reliability of the sports bra heart rate monitor decreased as intensity decreased (Rest Avg HR R = 0.783, Stage 1 Avg HR R = 0.869, Stage 2 Avg HR R = 0.508, Stage 3 Avg HR R = 0.198). The heart rate monitor was not valid as intensity increased (Rest Avg HR r = 0.846, Stage 1 Avg HR r = 0.681, Stage 2 Avg HR r = 0.069, Stage 3 Avg HR r = 0.016). Bland Altman analysis showed minimal bias for average HR during Rest (bias = -0.40). There was a large bias for average HR during Stage 3 (bias = 22.59). CONCLUSION: Overall, the sports bra heart rate measurements displayed good reliability and accuracy during resting conditions but lost accuracy as intensity increased. The findings of this study challenge the usefulness of the sports bra heart rate monitor for assessing heart rate in female athletes. Supported by: No acknowledgments to disclose.