Accuracy of smartphone application to monitor heart rate.

BACKGROUND: The use of smartphone applications to monitor heart rate has become increasingly popular. However, there is limited research available on the validity of these applications. The purpose of this study was to examine the accuracy of a free heart rate monitoring application on two smartphone platforms while at rest and during moderate intensity exercise. One heart rate monitor application was chosen for two different technological platforms. METHODS: Twenty-four adults aged 18 and older (six males, 18 females) were randomly assigned a platform. Two groups were formed based on the platform being utilized. Both groups were monitored using an electrocardiograph (ECG) and the smart phone application. Heart rate for each participant was recorded while seated before exercise, and during moderate intensity exercise on an elliptical machine. Measurements were recorded in one-minute intervals. RESULTS: Data was analyzed using correlations and t-tests between platforms. All data was analyzed for both resting and exercise heart rate averages. There was no significant difference in heart rate while seated, t-test (-1.33; P=0.197) nor exercise heart rate, t-test (-1.54; P=0.142) when comparing means of the two platforms to an ECG. CONCLUSIONS: The applications chosen for both platforms to monitor heart rate were found to be fairly accurate, especially at rest. There are small user adaptations for monitoring heart rate, but heart rate applications provide a low-cost and efficient method for non-medical heart rate tracking. Future research should investigate the difference in accuracy for skin tone, ethnicity, race, hand size, and callosity of fingertips.

Comparison of Resistance Exercise Perceived Exertion and Muscle Activation at Varied Submaximal Durations, Loads, and Muscle Actions.

Hollander, DB, Worley, JR, Asoodeh, M, Wakesa, D, Magnuson, M, Dantzler, DK, Didier, JJ, and Kraemer, RR. Comparison of resistance exercise perceived exertion and muscle activation at varied submaximal durations, loads, and muscle actions. J Strength Cond Res 31(5): 1387-1394, 2017-Previous studies investigating muscle activation from dynamic, plate-loaded, concentric (CON) and eccentric (ECC) muscle contractions have not accounted for the greater absolute strength of ECC contractions. The purpose of the study was to determine the effect of different dynamic muscle contraction durations, loads, and contraction types (CON and ECC) on perceived exertion and muscle activation differences in 6 women (mean ± SD age, height, weight, body mass index 22.83 ± 2.56 years, 1.65 ± 0.261 m, 68.56 ± 2.72 kg, 25.26 ± 4.39 kg·m). The participants were recruited and trained to move weight at the appropriate duration (2, 3, 4, and 5 seconds) for leg extension using a displacement apparatus (sonic emitter, auditory) and a computer program (visual feedback of bar displacement). Concentric and ECC 1 repetition maximum (1RM) were determined for leg extension for the midrange 3-second duration. Thirty, 50, and 70% of either CON or ECC 1RM were loaded for the remainder of the sessions. Subjects were then assigned to complete trials in a counterbalanced fashion for load, contraction type, and contraction duration. Rating of perceived exertion (RPE) significantly increased in response to load (30, 50, and 70%) regardless of contraction type as did electromyography (EMG) root mean square amplitude. Greater time under tension significantly increased RPE regardless of contraction type during knee extension exercise. The EMG amplitude was less distinguishable between 2, 3, 4, and 5 seconds of contractions. The data highlight the effort sense distinctions made by women at submaximal exercise loads during knee extension. These findings should be used to develop effective resistance exercise protocols that facilitate positive perceptions and adherence resistance exercise loads, durations of contraction, and contraction type.

Testing Postural Stability: Are the Star Excursion Balance Test and Biodex Balance System Limits of Stability Tests Consistent?

There are a variety of options to test postural stability; however many physical tests lack validity information. Two tests of postural stability - the Star Excursion Balance Test (SEBT) and Biodex Balance System Limits of Stability Test (LOS) - were examined to determine if similar components of balance were measured. Healthy adults (n=31) completed the LOS (levels 6 and 12) and SEBT (both legs). SEBT directions were offset by 180° to approximate LOS direction. Correlations and partial correlations controlling for height were analyzed. Correlations were significant for SEBT 45° and LOS back-left (6: r=-0.41; 12: r=-0.42; p<0.05), SEBT 90° and LOS 6 left (r=-0.51, p<0.05), SEBT 135(o) and LOS 6 front-left (r=-0.53, p<0.05), SEBT overall and LOS 6 overall (r=-0.43, p<0.05). Partial correlations were significant for SEBT 90° and LOS 6 left (rSEBT,LOS·H=-0.45, p<0.05) and SEBT 135° and LOS 6 front-left (rSEBT,LOS·H=-0.51, p<0.05), and SEBT overall and LOS 6 overall (rSEBT,LOS·H=-0.37, p<0.05). These findings indicate the tests seem to assess different components of balance. Research is needed to determine and define what specific components of balance are being assessed. Care must be taken when choosing balance tests to best match the test to the purpose of testing (fall risk, athletic performance, etc.).