Are Activity Wrist-Worn Devices Accurate for Determining Heart Rate during Intense Exercise?

The market for wrist-worn devices is growing at previously unheard-of speeds. A consequence of their fast commercialization is a lack of adequate studies testing their accuracy on varied populations and pursuits. To provide an understanding of wearable sensors for sports medicine, the present study examined heart rate (HR) measurements of four popular wrist-worn devices, the (Fitbit Charge (FB), Apple Watch (AW), Tomtom runner Cardio (TT), and Samsung G2 (G2)), and compared them with gold standard measurements derived by continuous electrocardiogram examination (ECG). Eight athletes participated in a comparative study undergoing maximal stress testing on a cycle ergometer or a treadmill. We analyzed 1,286 simultaneous HR data pairs between the tested devices and the ECG. The four devices were reasonably accurate at the lowest activity level. However, at higher levels of exercise intensity the FB and G2 tended to underestimate HR values during intense physical effort, while the TT and AW devices were fairly reliable. Our results suggest that HR estimations should be considered cautiously at specific intensities. Indeed, an effective intervention is required to register accurate HR readings at high-intensity levels (above 150 bpm). It is important to consider that even though none of these devices are certified or sold as medical or safety devices, researchers must nonetheless evaluate wrist-worn wearable technology in order to fully understand how HR affects psychological and physical health, especially under conditions of more intense exercise.

Near-infrared transmittance pulse oximetry with laser diodes.

Pulse oximeters are widely used for noninvasive monitoring of oxygen saturation in arterial blood hemoglobin. We present a transmittance pulse oximetry system based on near-infrared (NIR) laser diodes (750 and 850 nm) for monitoring oxygen saturation of arterial blood hemoglobin. The pulse oximetry system is made up of the optical sensor, sensor electronics, and processing block. Also, we show experimental results obtained during the development of the whole NIR transmittance pulse oximetry system along with modifications in the sensor configuration, signal processing algorithm, and calibration procedure. Issues concerning wavelength selection and its implications for the improvement of the transmittance pulse oximetry technique are discussed. The results obtained demonstrate the proposed system's usefulness in monitoring a wide range of oxygen saturation levels.

Functional improvement in patients with dilated cardiomyopathy after the intracoronary infusion of autologous bone marrow mononuclear cells.

INTRODUCTION AND OBJECTIVES: Different studies have shown improvement in patients with idiopathic nonischemic dilated cardiomyopathy treated with cell-therapy. However, factors influencing responsiveness are not well known. This trial investigates functional changes and factors influencing the 6-month gain in ejection fraction in 27 patients with dilated cardiomiopathy treated with intracoronary cell-therapy. METHODS: Patients received intracoronary infusion of autologous bone-marrow mononuclear cells (mean infused, 10.2 [2.9]×10(8)). Flow cytometry and functional analyses of the cells were also performed. RESULTS: The 6-month angiographic gain in ejection fraction ranged from -9% to 34% (mean, 9%). These changes were distinguished into 2 groups: 21 patients (78%) with a significant improvement at the 6-month evaluation (mean gain, 14 [7]%), and 6 patients who had no response (mean gain, -5 [3]%). The responders were younger as compared to the nonresponders (50 [12] years vs 62 [9] years; P<.04). There was an inverse correlation (r=-0.41; P<.003) between the gain in ejection fraction and the high density lipoprotein level, suggesting higher functional gain with low high density lipoprotein levels. The 24 h migratory capability of the infused cells was significantly reduced in the responders' group (5.4 [1.7]×10(8) vs 8.1 [2.3]×10(8); P<.009 for vascular endothelial growth factor and 5.8 [1.7]×10(8) vs 8.4 [2.9]×10(8); P<.002 for stromal cell-derived factor-1). CONCLUSIONS: Younger patients with dilated cardiomiopathy and lower plasma high density lipoprotein levels gain greater benefit from intracoronary cell-therapy. Functional improvement also seems to be enhanced by a lower migratory capacity of the infused cells.

Mejoría funcional en pacientes con miocardiopatía dilatada tras la infusión intracoronaria de células mononucleares autólogas de la médula ósea / Functional improvement in patients with dilated cardiomyopathy after the intracoronary infusion of autologous bone marrow mononuclear cells

Introducción y objetivos. Diferentes estudios han mostrado mejoría funcional en pacientes con miocardiopatía dilatada no isquémica tratada con terapia celular. Sin embargo, los factores que influyen en la respuesta no son bien conocidos. El presente estudio investiga los cambios funcionales y los factores que influyen en la mejora de la fracción de eyección a los 6 meses en 27 pacientes con miocardiopatía dilatada tratados con terapia celular intracoronaria. Métodos. Los pacientes recibieron una infusión intracoronaria de células mononucleares autólogas de la médula ósea (media de células infundidas, 10,2±2,9 × 108). En todos se efectuó análisis funcional y citometría de flujo de las células infundidas. Resultados. La ganancia en fracción de eyección observada a los 6 meses osciló entre el ¿9 y el 34% (media, 9%). Estos cambios formaron dos grupos de pacientes: 21 (78%) que mostraron una mejora significativa (ganancia media, 14±7%), frente a 6 (22%) que no mostraron respuesta (ganancia media, ¿5±3%). Los respondedores eran más jóvenes (50±12 frente a 62±9 años; p<0,04). Se encontró una correlación inversa (r=¿0,41; p<0,003) entre la ganancia en la fracción de eyección y los valores basales de lipoproteínas de alta densidad. La capacidad migratoria de las células infundidas a las 24h estaba significativamente reducida en el grupo de respondedores (factor de crecimiento del endotelio vascular, 5,4±1,7 × 108 frente a 8,1±2,3 × 108; p<0,009; factor 1 derivado de células estromales, 5,8±1,7 × 108 frente a 8,4±2,9 × 108; p<0,002). Conclusiones. Los pacientes más jóvenes con miocardiopatía dilatada y concentración plasmática de lipoproteínas de alta densidad más baja parecen tener mayor beneficio funcional tras la terapia celular. La mejoría funcional también parece aumentada en los pacientes con menor capacidad migratoria de las células infundidas (AU)

Introduction and objectives. Different studies have shown improvement in patients with idiopathic nonischemic dilated cardiomyopathy treated with cell-therapy. However, factors influencing responsiveness are not well known. This trial investigates functional changes and factors influencing the 6-month gain in ejection fraction in 27 patients with dilated cardiomiopathy treated with intracoronary cell-therapy. Methods. Patients received intracoronary infusion of autologous bone-marrow mononuclear cells (mean infused, 10.2 [2.9]×108). Flow cytometry and functional analyses of the cells were also performed. Results. The 6-month angiographic gain in ejection fraction ranged from −9% to 34% (mean, 9%). These changes were distinguished into 2 groups: 21 patients (78%) with a significant improvement at the 6-month evaluation (mean gain, 14 [7]%), and 6 patients who had no response (mean gain, −5 [3]%). The responders were younger as compared to the nonresponders (50 [12] years vs 62 [9] years; P<.04). There was an inverse correlation (r=−0.41; P<.003) between the gain in ejection fraction and the high density lipoprotein level, suggesting higher functional gain with low high density lipoprotein levels. The 24h migratory capability of the infused cells was significantly reduced in the responders’ group (5.4 [1.7]×108 vs 8.1 [2.3]×108; P<.009 for vascular endothelial growth factor and 5.8 [1.7]×108 vs 8.4 [2.9]×108; P<.002 for stromal cell-derived factor-1). Conclusions. Younger patients with dilated cardiomiopathy and lower plasma high density lipoprotein levels gain greater benefit from intracoronary cell-therapy. Functional improvement also seems to be enhanced by a lower migratory capacity of the infused cells (AU)