This work aims to present concepts related to ethical issues in conducting and reporting scientific research in a clear and straightforward manner. Considerations around research design including authorship, sound research practices, non-discrimination in subject recruitment, objectivity, respect for intellectual property, and financial interests are detailed. Further, concepts relating to the conducting of research including the competency of the researcher, conflicts of interest, accurately representing data, and ethical practices in human and animal research are presented. Attention pertaining to the dissemination of research including plagiarism, duplicate submission, redundant publication, and figure manipulation is offered. Other considerations including responsible mentoring, respect for colleagues, and social responsibility are set forth. The International Journal of Exercise Science will now require a statement in all subsequent published manuscripts that the authors have complied with each of the ethics statements contained in this work.

Wearable physical activity trackers are a popular and useful method to collect biometric information at rest and during exercise. The purpose of this systematic review was to summarize recent findings of wearable devices for biometric information related to steps, heart rate, and caloric expenditure for several devices that hold a large portion of the market share. Searches were conducted in both PubMed and SPORTdiscus. Filters included: humans, within the last 5 years, English, full-text, and adult 19+ years. Manuscripts were retained if they included an exercise component of 5-min or greater and had 20 or more participants. A total of 10 articles were retained for this review. Overall, wearable devices tend to underestimate energy expenditure compared to criterion laboratory measures, however at higher intensities of activity energy expenditure is underestimated. All wrist and forearm devices had a tendency to underestimate heart rate, and this error was generally greater at higher exercise intensities and those that included greater arm movement. Heart rate measurement was also typically better at rest and while exercising on a cycle ergometer compared to exercise on a treadmill or elliptical machine. Step count was underestimated at slower walking speeds and in free-living conditions, but improved accuracy at faster speeds. The majority of the studies reviewed in the present manuscript employed different methods to assess validity and reliability of wearable technology, making it difficult to compare devices. Standardized protocols would provide guidance for researchers to evaluate research-grade devices as well as commercial devices used by the lay public.

Validation of heart rate responses in wearable technology devices is generally composed of laboratory-based protocols that are steady state in nature and as a result, high accuracy measures are returned. However, there is a need to understand device validity in applied settings that include varied intensities of exercise. The purpose was to determine concurrent heart rate validity during trail running. Twenty-one healthy participants volunteered (female n = 10, [mean (SD)]: age = 31 [11] years, height = 173.0 [7] cm, mass = 75.6 [13] kg). Participants were outfitted with wearable technology devices (Garmin Fenix 5 wristwatch, Jabra Elite Sport earbuds, Motiv ring, Scosche Rhythm+ forearm band, Suunto Spartan Sport watch with accompanying chest strap) and completed a self-paced 3.22 km trail run while concurrently wearing a criterion heart rate strap (Polar H7 heart rate monitor). The trail runs were out-and-back with the first 1.61 km in an uphill direction, and the 1.61 return being downhill in nature. Validity was determined through three methods: Mean Absolute Percent Error (MAPE), Bland-Altman Limits of Agreement (LOA), and Lin’s Concordance Coefficient (r_C). Validity measures overall are as follows: Garmin Fenix 5 (MAPE = 13%, LOA = -32 to 162, r_C = 0.32), Jabra Elite Sport (MAPE = 23%, LOA = -464 to 503, r_C = 0.38), Motiv ring (MAPE = 16%, LOA = -52 to 96, r_C = 0.29), Scosche Rhythm+ (MAPE = 6%, LOA = -114 to 120, r_C = 0.79), Suunto Spartan Sport (MAPE = 2%, LOA = -62 to 61, r_C = 0.96). All photoplethysmography-based (PPG) devices displayed poor heart rate agreement during variable intensity trail running. Until technological advances occur in PPG-based devices allowing for acceptable agreement, heart rate in outdoor environments should be obtained using an ECG-based chest strap that can be connected to a wristwatch or other comparable receiver.

Consumer wearable technology use is widespread and there is a need to validate measures obtained in uncontrolled settings. Because no standard exists for the treatment of heart rate data during exercise, the effect of different approaches on reliability (Coefficient of Variation [CV], Intraclass Correlation Coefficient [ICC]) and validity (Mean Absolute Percent Error [MAPE], Lin’s Concordance Correlation Coefficient [CCC)] were determined in the Polar Verity Sense and OH1 during trail running. The Verity Sense met the reliability (CV < 5%, ICC > 0.7) and validity thresholds (MAPE < 5%, CCC > 0.9) in all cases. The OH1 met reliability thresholds in all cases except entire session average (ICC = 0.57). The OH1 met the validity MAPE threshold in all cases (3.3–4.1%), but not CCC (0.6–0.86). Despite various heart rate data processing methods, the approach may not affect reliability and validity interpretation provided adequate data points are obtained. It is also possible that a large volume of data will artificially inflate metrics.

To evaluate if the Hexoskin smart shirt (HxS) would produce valid and reliable measurements for heart rate (HR), respiratory rate (RR), minute ventilation (VE), step count (SC), and energy expenditure (EE) when compared to a Polar T-31 heart rate monitor, an Applied Electrochemistry Moxus Metabolic System, and a manual step count. A two-day walking treadmill protocol with participants walking for 3 minutes at 3 speeds (1.5mph, 2.5mph, 3.5mph, 0% grade) was performed. Forty-nine volunteers participated the first day, forty-six on the second, thirty-one were used for reliability. Values calculated for the HxS data used Pearson’s product-moment correlation (p < 0.05; r ≥ 0.70) for validity and Cronbach’s a (≥ 0.70) for reliability. HxS HR (1.5mph; p<0.01, r=0.86, a=0.86. 2.5mph; p<0.01, r=0.81, a=0.88. 3.5mph; p<0.01, r=0.85, a=0.85), HxS RR (1.5mph; p<0.01, r=0.87, a=0.93. 2.5mph; p<0.01, r=0.86, a=0.92. 3.5mph; p<0.01, r=0.71, a=0.76), HxS VE (1.5mph; p=0.66, r=0.11, a=0.70. 2.5mph; p=0.01, r=0.15, a=0.73. 3.5mph; p=0.31, r=0.08, a=0.14), HxS SC (1.5mph; p=0.90, r=-0.01, a=0.70. 2.5mph; p=0.22, r=0.13, a=0.86. 3.5mph; p<0.01, r=0.74, a=0.85), HxS EE (1.5mph; p<0.01, r=0.56, a=0.85. 2.5mph; p<0.01, r=0.50, a=0.83. 3.5mph; p<0.01, r=0.51, a=0.80). HxS HR and RR provided valid and reliable measures at all three speeds while VE, SC, and EE had a mixture of results based on speed. These results are important in the use of the Hexoskin in an accurate manner for athletes, coaches, and for the potential medical applications being advocated in the field of telemedicine procedures.

The purpose of this review was to evaluate the current state of the literature and to identify the types of study designs, wearable devices, statistical tests, and exercise modes used in validation and reliability studies conducted in applied settings/outdoor environments. This was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. We identified nine articles that fit our inclusion criteria, eight of which tested for validity and one tested for reliability. The studies tested 28 different devices with exercise modalities of running, walking, cycling, and hiking. While there were no universally common analytical techniques used to measure accuracy or validity, correlative measures were used in 88% of studies, mean absolute percentage error (MAPE) in 75%, and Bland–Altman plots in 63%. Intra-class correlation was used to determine reliability. There were not any universally common thresholds to determine validity, however, of the studies that used MAPE and correlation, there were only five devices that had a MAPE of < 10% and a correlation value of > 0.7. Overall, the current review establishes the need for greater testing in applied settings when validating wearables. Researchers should seek to incorporate multiple intensities, populations, and modalities into their study designs while utilizing appropriate analytical techniques to measure and determine validity and reliability.