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.

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.).

The effects of two different arm positions and weight status on select kinematic variables during the bodyweight squat.

The bodyweight squat is a common movement and is safe and effective. There are many variations and techniques, but little research has explored alterations of the movement. The purpose of this study was to examine the effects of 2 arm positions on select kinematic variables during the bodyweight squat. The participants were classified as normal-weight (NW: n = 17, height: 1.67 ± 0.06 m, weight: 61.25 ± 6.90 kg, body mass index [BMI]: 21.92 ± 1.68) or overweight (OW: n = 11, height: 1.68 ± 0.06 m, weight: 88.91 ± 16.86 kg, BMI: 31.64 ± 6.06) according to BMI. The participants completed a bodyweight squat with the arms held at the sides (AP1) followed by a bodyweight squat with the arms held at shoulder level (AP2). Reflective markers were placed on the shoulder, hip, knee, base of the fifth toe, and heel. Data were recorded and analyzed using Peak 9. Trunk and knee flexion was analyzed using separate repeated measures analyses of variance. Overweight participants exhibited reduced knee (OW: 75.56 ± 17.94°; NW: 83.73 ± 13.03°; p < 0.05) and trunk flexion (OW: -78.18 ± 17.72°; NW: -90.65 ± 17.57°; p = 0.05). Holding the arms at shoulder level resulted in greater knee flexion (AP1: 80.81 ± 15.17°; AP2: 86.31 ± 15.21°; p < 0.01). Both weight status and arm position affected the range of motion in the bodyweight squat. Using an arms-up position should be considered, especially for the OW population, to increase the benefits of the bodyweight squat by increasing the range of motion.