In my second highlight, Gillinov et al. examined the accuracy of optically based, wrist-worn heart rate monitors under a variety of exercise conditions in healthy, athletic volunteers. None of the wrist-worn heart rate monitors was as accurate as an electrocardiographic chest strap monitor. As previously reported, accuracy varied among monitoring devices. For the wrist worn monitors that were tested, the Apple Watch was the most accurate and the Fitbit Blaze the least accurate. None of the monitors performed well when subjects exercised on an elliptical trainer with arm levers, suggesting that these devices are vulnerable to motion artifact. Therefore, electrocardiographic chest strap monitors remain the gold standard and should be employed when accurate heart rate measurement is essential. Unfortunately, when using wrist worn monitors, periodic spurious readings are the rule rather than the exception.
Finally, Brellenthin et al. recruited 36 healthy men and women to study whether habitual levels of physical activity (low, moderate, or high) influenced endocannabinoid (eCB; AEA and 2-AG) levels and mood responses to exercise. After exercise, both AEA and 2-AG increased, and mood improved in all three physical activity groups. Interestingly, physical activity, but not cardiorespiratory fitness, was inversely associated with basal AEA concentrations. These findings appear to implicate the eCB system in motivated physical activity behaviors. Brellenthin et al. also found that acute eCB increases were associated with positive mood outcomes, which adds to the growing body of evidence suggesting eCB may contribute to the diverse psychological benefits that occur with exercise and may provide insight regarding the higher rates of physical inactivity and eCB dysfunction observed in psychiatric conditions (e.g., major depressive disorder, substance use disorders).
L. Bruce Gladden
School of Kinesiology