The Influence of Antenna Height on the Measurement of Collective Variables Using an Ultra-Wide Band Based Local Positioning System in Team Sports

Ultra-wide band (UWB) based local positioning systems (LPS) are based on devices and a portable antenna set. The optimal installation height of the antennae is crucial to ensure data accuracy. Collective variables are metrics that consider at least two pairs of coordinates, which may lead to lower precision than an individual one. Therefore, the aim of this study was to compare the influence of antenna height with collective metrics using a UWB (i.e., IMU; WIMU PRO™, RealTrack Systems, Almeria, Spain) based LPS. Data acquisition was carried out in a basketball court measuring 28 × 15 m. Five devices were used; one of which was carried by a healthy and well-trained athlete (age: 38 years, mass: 76.34 kg, height 1.70 m), while each of the remaining four was positioned on a tripod in one of the four corners of the court. Four kinds of variables were extracted: (1) static distances, (2) dynamic distances, (3) static areas and (4) dynamic areas in all antenna installation modes of 0.15, 1.30 and 2.00 m. The results showed that the antenna of 1.30 m provided better accuracy for all measures (% difference range from −0.94 to 1.17%) followed by the antenna of 2.00 m (% difference range from −2.50 to 2.15%), with the antenna of 0.15 m providing the worst accuracy level (% difference range from −1.05 to 3.28%). Overall, the measurements of distance metrics showed greater accuracy than area metrics (distance % difference range from −0.85 to 2.81% and area % difference range from −2.50 to 3.28). In conclusion, the height of the antennae in basketball courts should be similar to the height at which the devices are attached to a player’s upper back. However, as the precision is sensitive to the magnitude of the measure, further studies should assess the effects of the relative height of antennae in team sports with greater playing spaces.

Abstract 16689: Smartphone-enabled Device for the Monitoring of Blood Volume Variations Using Magnetohydrodynamic Voltages

Background: Blood volume assessment is a valuable clinical metric, which can diagnostically be used to assess tissue health, monitor patient rehabilitation, and track the progression of wound healing. Currently there exists several methods to assess flow (MRI, US), but are either limited in cost or portability, and may require injection of contrast agents. Magnetohydrodynamic voltages (VMHD) are induced through blood flow interactions with an external magnetic field, and have been successfully measured using a modified ECG recorder and software package [1]. We hypothesize that a portable device capable of measuring induced VMHD could be used to rapidly quantify changes in blood flow. Objectives: Develop a portable device capable of monitoring of variations in blood volumes using induced VMHD. Methods: A portable smartphone-based ECG monitor was developed to use methods proposed in [1] to extract a metric proportional to blood flow from acquired ECGs (Fig. 1a). ECGs were acquired in two healthy volunteers, the second being a trained athlete. VMHD was induced in the carotid artery while in the presence of 0.4T static magnetic field generated by a neodymium magnet embedded in the monitor (Fig. 1b). VMHD signal extraction was performed to isolate the voltage induced by the magnet. Integrating over the VMHD yielded a metric proportional to blood volume [1,2]. Trials were performed at rest and at an elevated heart rate (HR) from exercise stress. Results: Induced VMHD was shown to increase from the baseline during exercise by 59% and 106% for the healthy subject and the athlete, respectively; resulting in a 47% difference in VMHD variations between the trained athlete and the healthy subject (Fig. 1c). Conclusions: A stand-alone device capable of quickly assessing blood volumes in the field using custom hardware and smartphone technology was developed. The ability of the device to quantify VMHD-derived blood flow was demonstrated. Ref: [1] Tse, MRM, 2013. [2] Gregory, JCMR, 2015.

What is Best Practice for Training Intensity and Duration Distribution in Endurance Athletes?

Successful endurance training involves the manipulation of training intensity, duration, and frequency, with the implicit goals of maximizing performance, minimizing risk of negative training outcomes, and timing peak fitness and performances to be achieved when they matter most. Numerous descriptive studies of the training characteristics of nationally or internationally competitive endurance athletes training 10 to 13 times per week seem to converge on a typical intensity distribution in which about 80% of training sessions are performed at low intensity (2 mM blood lactate), with about 20% dominated by periods of high-intensity work, such as interval training at approx. 90% VO2max. Endurance athletes appear to self-organize toward a high-volume training approach with careful application of high-intensity training incorporated throughout the training cycle. Training intensification studies performed on already well-trained athletes do not provide any convincing evidence that a greater emphasis on high-intensity interval training in this highly trained athlete population gives long-term performance gains. The predominance of low-intensity, long-duration training, in combination with fewer, highly intensive bouts may be complementary in terms of optimizing adaptive signaling and technical mastery at an acceptable level of stress.