We thank all participants in this study and technical laboratory staff for their support in the measurements taken at the Laboratory of Exercise Physiology. The authors FC-B and ME-R were partially supported by the III, IV, and V Research &#38; Innovation Competitions of the School Health Sciences (Faculty of Medicine, Pontificia Universidad Cat&#243;lica de Chile).&#160;The author RC-C was funded by Project supported by the Competition for Research Regular Projects, year 2023, code LPR23-17, Universidad Tecnol&#243;gica Metropolitana.

The protocol was approved by the Institutional Review Board of the Pontificia Universidad Cat&#243;lica de Chile (projects n&#186; 210525001 and 220608010), and the study was conducted in accordance with the Declaration of Helsinki. All participants provided written informed consent before participating in the testing described.
1. Placement and setup of NIRS wearables
NOTE: Various NIRS wearables and data acquisition software can be utilized. Researchers should thoroughly consult the manufacturer&#39;s instructions and guidelines to ensure proper setup and usage. In this study, the devices that use a continuous wave register of the NIRS signal are used. These commercial devices are easy to use, but they can only detect changes in light attenuation relative to the reference or baseline phase and cannot detect absolute concentrations like other devices that employ a time-domain register of NIRS.

<ol>
	<li>NIRS wearables preparation and general placement guidelines
	<ol>
		<li>Before placing the devices and starting the measurements, ensure that all wearables are fully charged. 
		NOTE: For the devices used in this study, the manufacturer reports that a battery with a full charge can register 6&#8211;8 h continuously.</li>
		<li>Apply double-sided adhesive tape to all wearables to secure them to the participant&#39;s skin, ensuring that the tape does not obstruct the light emitters and detectors.</li>
		<li>Cover all wearables with a layer of cling film, followed by a layer of a waterproof adhesive dressing to protect them from sweat.</li>
		<li>Before placing the devices, clean the target area with an alcohol pad to remove any residue that may interfere with the register (e.g., creams, cosmetics, etc.). If necessary, shave the area around the target site, as hair can interfere with NIRS signals. 
		NOTE: It is recommended that a thorough hand wash be performed before placing any device on the participant&#39;s skin to prevent potential contamination. Wearing gloves is encouraged, as it can further reduce the risk of contamination.</li>
		<li>Once all wearables are correctly placed on the participant&#39;s skin (see section 1.2), secure them with a layer of elastic therapeutic tape. If additional fixation is needed, use an elastic bandage wrap of dark color, ensuring that excessive compression does not alter the measurements (less than the 25 mm Hg capillary occlusion pressure measured by a conventional sphygmomanometer).</li>
		<li>Place a black cloth over all wearables to prevent ambient light from penetrating. If covering the area with a cloth is not possible (around 6 cm2), use black elastic therapeutic tape to block ambient light.</li>
	</ol>
	</li>
	<li>NIRS device placement 
	NOTE: Ensure that NIRS wearables devices are placed so that ON/OFF and setting buttons are easily accessible.
	<ol>
		<li>Prefrontal Cortex: Place the NIRS probe on the left or right dorsolateral prefrontal cortex, approximately 10 mm above the participant&#39;s superciliary arch, similar to Fp1 electrode placement according to the modified international EEG 10-20 system21.</li>
		<li>m.Intercostales: Place the NIRS probe over the 7th intercostal space at the right anterior axillary line22,23,24. If, for some reason, it is not positioned over the right hemithorax, position it over the left hemithorax, but the signal from the heart rate may be more pronounced on the left side.
		<ol>
			<li>To confirm NIRS penetration depth, use a B&#8211;mode ultrasound to verify the distance from subcutaneous tissue to the outer border of the m.Intercostales. For measurements at m.Intercostales, ensure that the distance between skin and muscle is less than 15 mm.</li>
		</ol>
		</li>
		<li>m.Vastus Lateralis: Place the NIRS probe 5 cm lateral to the imaginary line&#39;s midpoint, connecting the patella&#39;s upper edge and the greater trochanter of the femur24,25,26.
		<ol>
			<li>To ensure that the adipose tissue thickness (ATT) does not alter the register of the NIRS signal, measure skinfold thickness to confirm the NIRS penetration depth27. For measurements at m.Vastus Lateralis, ensure that the ATT is less than 20 mm.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>NIRS software setup
	<ol>
		<li>Once all NIRS wearables are correctly placed (see section 1.2), power them ON before starting the measurement.</li>
		<li>Launch the data acquisition software provided by the manufacturer, create a new file, and link the NIRS wearables.</li>
		<li>After all NIRS wearables are successfully linked, set the sampling rate to 10 Hz for data acquisition and analog-to-digital conversion for the assessed tissues. For prefrontal cortex measurements, adjust the differential pathlength factor (DPF) according to the age-dependent DPF for each participant28. For muscle measurement, set the DPF to 4, as used in previous protocols with athletes as subjects of study29,30.</li>
	</ol>
	</li>
</ol>
2. Calibration and setup of ergospirometer 
<ol>
	<li>Volume calibration
	<ol>
		<li>Open the ergospirometer&#39;s software provided by the manufacturer to begin the calibration process.</li>
		<li>Attach the flow meter to a 28 mm turbine with a syringe adapter. Connect one corrugated tube to the syringe adapter and the other to a 3 L calibration syringe.</li>
		<li>Perform six withdrawal/injection maneuvers, maintaining a constant flow rate. Upon completion, the software will automatically confirm if the calibration test has passed.</li>
	</ol>
	</li>
	<li>Gas calibration 
	NOTE: Ensure the flow calibration is done before starting the gas calibration.
	<ol>
		<li>Air calibration
		<ol>
			<li>Ensure the sample line from the gas analyzer is disconnected from the calibration port and hanging freely. Then, initialize the calibration process.</li>
			<li>During calibration, a stable flat line is observed as the concentrations of oxygen (O2) and carbon dioxide (CO2) do not vary significantly (less than 5%). Once air calibration has been successfully completed, proceed to the metabolic gas calibration.</li>
		</ol>
		</li>
		<li>Metabolic gas calibration
		<ol>
			<li>Open the gas valves and verify that adequate pressure is delivered to the system by checking the manometer (consult the manufacturer for specific instructions).</li>
			<li>Connect the sample line to the calibration port and initialize the calibration process. Perform a 3 min pre-heating before starting the calibration, as advised by the manufacturer.</li>
			<li>If done correctly, after the 3 min pre-heating period, two flat lines should be observed: one fluctuating between room air (approximately 21.00% O2 and 0.04% CO2) and the other between the calibration gas (16.00% O2 and 5.00% CO2).</li>
			<li>Finally, disconnect the sample line from the calibration port and attach it to the mouthpiece that will be used for the upcoming test.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
3. ECG electrode placement (12 leads)
<ol>
	<li>Prepare the skin by exfoliating with a cream and/or shaving any hair from the electrode placement sites if necessary. Clean the areas with an alcohol pad to remove any superficial tissue residues.</li>
	<li>Place the ECG electrodes as follows31:
	<ol>
		<li>Place the bipolar leads (Limb lead electrodes) as follows: Left arm (LA): left side of subclavicular fossa; Right arm (RA): right side of subclavicular fossa; Left leg (LL): anterior projection of left femoral head; Right leg (RL): anterior projection of right femoral head.</li>
		<li>Place the precordial lead electrodes as follows: V1: 4th intercostal space to the right of the sternum; V2: 4th intercostal space to the left of the sternum (in line with V1); V3: Midway between V2 and V4; V4: 5th intercostal space at the midclavicular line; V5: anterior axillary line at the same level as V4; V6: midaxillary line at the same level as V4 and V5.</li>
	</ol>
	</li>
</ol>
4. Incremental maximal exercise test (cardiopulmonary exercise testing, CPET)
<ol>
	<li>Ask the participant to sit on the bike, ensuring that the seat and handlebars are adjusted to their height for optimal comfort and positioning. 
	NOTE: It is advised to set the seat height so that the knee is slightly bent at full extension32. The handlebars should be positioned to allow for a slight flexion of the elbows.</li>
	<li>Attach a pulse oximeter to the participant&#39;s ear lobe, ensuring the site is clean by wiping it with an alcohol pad.</li>
	<li>Explain the protocol and instruct the participant to breathe through the mask before, during, and after the test. 
	NOTE: The participant must avoid talking or whistling while wearing the mask, as this can affect the ergospirometer&#39;s readings33.</li>
	<li>Once the participant is positioned and prepared, have the participant extend the right leg and wait 2 min for the start instruction (initial rest stage). Have the participant pedal at a cadence between 80&#8211;100 rpm for 6 min at 0.6 W&#183;kg-1 and 0.8 W&#183;kg-1 for women/men, respectively (warm-up phase). Then, increment the workload at a rate of 20 W&#183;min-&#185; for women and 25 W&#183;min-&#185; for men until the participant reaches exhaustion (exercise phase).</li>
	<li>After completing the exercise phase, instruct the participant to remain still and continue breathing into the mask for 3 min (cool-down or recovery phase).</li>
	<li>Once the exercise protocol is finished, carefully remove the pulse oximeter from the earlobe, the mask, all three NIRS wearables, and the ECG electrodes. 
	NOTE: To keep the laboratory ambient condition (e.g., air temperature ~20 &#177; 2 &#176;C, relative humidity ~40% &#177; 5%), it is a crucial criterion. Some participants can show a high sweat rate, which interferes with the fixation of devices on the skin and affects NIRS data recording. The use of ventilators can help to reduce hot thermoregulation by sweating.</li>
</ol>

The authors declare no conflict of interest.

There is significant potential in using NIRS wearables as a complementary tool to CPET for evaluating athletic performance and identifying central and peripheral exercise&#8211;limiting factors in aerobic or endurance athletes, given that NIRS technology has proven its validity and reliability in assessing microvascular hemodynamics in both cerebral and muscular regions37,38. However, to maximize the benefits of this technology, several considerations must be add...

Endurance athletes rely on an efficient balance of oxygen delivery and uptake to sustain high&#8211;intensity exercise and enhance their athletic performance1,2. The maximal oxygen uptake test (VO2-max) is a vital physiological assessment that determines sports performance by analyzing exhaled&#8211;gases and cardiorespiratory variables during incremental exercise intensity1. This assessment, known as ergospirometry or Cardiopulmonary Exercise Testing (CPET), reflects the exercise response of the cardiovascular, respiratory, and muscular systems3. Along these lines, the increased energy cost associated with breathing, referred to as the cost of breathing (COB), heightens the demand for nutrients and oxygen in the surrounding tissues. This phenomenon has been documented to potentially reduce blood flow to the muscles involved in active movements, resulting in a decreased tolerance to physical exertion and an early cessation of exercise progression due to the metabolic reflex4.
During a VO2&#8211;max test, it is also possible to identify the ventilatory thresholds (VTs), which correspond to specific exercise intensities marking the transition from aerobic to anaerobic metabolism (aerobic threshold or ventilatory threshold 1 [VT1], and anaerobic threshold or respiratory compensation point [RCP] or ventilatory threshold 2 [VT2])5. The VTs reflect the ventilatory responses that compensate for metabolic changes during incremental exercise6. By identifying these thresholds, CPET offers a comprehensive evaluation by integrating the responses of multiple biological systems critically engaged during high&#8211;intensity exercise.
However, while ergospirometry is widely considered the gold standard for evaluating CPET, it does not capture metabolic changes occurring at the muscle level. These changes are crucial for understanding the physiological limiting factors associated with the lack of progression during high&#8211;intensity exercise in endurance athletes. In this context, NIRS technology has emerged as a valuable tool in exercise science, aiding in analyzing hemodynamic variables at the microvascular muscle level7.
In recent years, sports professionals and researchers have used a wide range of commercial wearables equipped with NIRS technology to explore non&#8211;invasive muscular changes during exercise, providing the ability to determine VT1 and VT2 with this technology8. Thus, the integrative analysis of data from NIRS and CPET offers a comprehensive understanding of physiological responses to exercise.
The NIRS technology utilizes the modified Beer-Lambert law to quantify changes (D) in the concentrations of oxyhemoglobin (O2-Hb) and deoxyhemoglobin (H-Hb) during exercise7. At the local tissue level, a decrease in O2-Hb reflects an increase in local metabolic demand, while an increase in H-Hb reflects an increase in oxygen extraction. Total hemoglobin (tHb), the sum of O2-Hb and H-Hb, is used as an index of local tissue blood flow. Conversely, the difference between O2-Hb and H-Hb (Hbdiff) provides an index of tissue oxygen extraction9. The tissular saturation index (TSI), calculated as the ratio of O2-Hb to tHb, reflects the tissue oxygen saturation level and indicates the balance between local oxygen delivery and uptake10,11. Thus, NIRS data give critical insights into the physiological status at the microvascular level, providing a detailed understanding of tissue oxygenation and hemodynamics that complements the information obtained from CPET.
This detailed understanding provided by NIRS technology extends to many practical applications. Recent research highlights the versatility of NIRS and demonstrates its practical application in monitoring respiratory12,13 and locomotor muscles7, as well as brain regions involved in motor act ideation, such as the prefrontal cortex (PFC)14,15. This broad applicability underscores the ability of NIRS to provide comprehensive insight into physiological responses to various types of muscle contractions (concentric or, eccentric, or isometric contractions) and exercise.
By analyzing exercise-induced DTSI at both the muscular and cerebral levels, NIRS provides a valuable potential for identifying associations between peripheral and central limiting factors that affect the progression of exercise16,17. For example, among central limiting factors, decreased blood flow resulting from cerebral vasoconstriction caused by compensatory hyperventilation due to elevated hydrogen levels from anaerobic metabolism and increased blood lactate during high-intensity exercise is a significant contributor to the reduction in TSI in the prefrontal cortex17,18. In contrast, peripheral limiting factors are characterized by an imbalance between oxygen supply and demand in the exercising musculature19. Reduced local oxygen delivery and increased oxygen consumption can lead to tissue deoxygenation, as evidenced by decreased TSI20. This distinction highlights the multifaceted nature of performance limitations during high&#8211;intensity exercise, where both central and peripheral mechanisms are critical. This understanding suggests that delaying the onset of these limiting factors during exercise may contribute to improved athletic performance.
To fully leverage the potential of NIRS technology in identifying these limitations, standardized procedures are essential to ensure high-quality data collection and analysis. This document outlines methods for conducting maximal endurance exercise testing using NIRS technology to collect physiological data and elucidate the relationship between central and peripheral limiting factors during high-intensity exercise in endurance athletes. The proposed protocol provides a standardized approach to ensure consistency and accuracy in assessing the physiological phenomena underlying these limiting factors.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Column Scale</td>
			<td>SECA</td>
			<td>711</td>
			<td>There are numerous alternatives to this item</td>
		</tr>
		<tr>
			<td>Portable Stadiometer&#160;</td>
			<td>SECA</td>
			<td>217</td>
			<td>There are numerous alternatives to this item</td>
		</tr>
		<tr>
			<td>12-lead ECG</td>
			<td>COSMED</td>
			<td>Quark T12x</td>
			<td>A 12-lead ECG provides a better understanding of HR during exercise and facilitates the detection of arrhythmias.</td>
		</tr>
		<tr>
			<td>Pulse Oxymeter</td>
			<td>COSMED</td>
			<td></td>
			<td>Integrated pulse oxymeter</td>
		</tr>
		<tr>
			<td>Ergoespirometer</td>
			<td>COSMED</td>
			<td>Quark-CPET</td>
			<td>Calibration gases and calibration syringe are included</td>
		</tr>
		<tr>
			<td>Cycle-ergometer</td>
			<td>Ergoline GmH</td>
			<td>ViaSprint 150P</td>
			<td>There are numerous alternatives to this item. Must ensure compatibility with provided software</td>
		</tr>
		<tr>
			<td>NIRS weareable</td>
			<td>Artinis Medical Systems</td>
			<td>Portalite</td>
			<td>Articulated NIRS weareable fits the surface where it&#39;s placed upon.&#160;</td>
		</tr>
		<tr>
			<td>NIRS weareable</td>
			<td>Artinis Medical Systems</td>
			<td>Portamon</td>
			<td>Portamon device provides better results on high adipose-tissue surfaces.</td>
		</tr>
		<tr>
			<td>Metabolic Data Management Software (OMNIA)</td>
			<td>COSMED</td>
			<td></td>
			<td>Software will vary upon system choice</td>
		</tr>
		<tr>
			<td>NIRS Data Management Software (Oxysoft)</td>
			<td>Artinis Medical Systems</td>
			<td></td>
			<td>Software will vary upon device choice</td>
		</tr>
		<tr>
			<td>Wireless Probe Type Ultrasound Scanner</td>
			<td>SONUS</td>
			<td>Duo LC</td>
			<td>There are numerous alternatives to this item</td>
		</tr>
	</tbody>
</table>

using near-infrared spectroscopy wearable devices to identify central versus peripheral limitations during exercise

The gold standard to assess the aerobic capacity in physically active subjects and athletes is the maximal oxygen consumption test (VO2&#8211;max), which involves analysis of exhaled&#8211;gases and cardiorespiratory variables obtained via the breath-by-breath method in an ergospirometer during an incremental exercise. However, this method cannot elucidate metabolic changes at the muscular level. Near-infrared spectroscopy (NIRS) has emerged as a valuable technology to evaluate local oxygen levels (Tissular Saturation Index, TSI) by quantifying the concentrations of oxygenated (O2-Hb) and deoxygenated (H-Hb) hemoglobin in the microvasculature of tissues. NIRS applications extend to respiratory and locomotor muscles, assessing metabolic changes associated with the cost of breathing (COB) and peripheral workload, respectively. Additionally, cerebral regions, such as the prefrontal cortex, have been explored with NIRS technology to assess physiological changes related to cognitive demand associated with planning or ideation of motor tasks linked to sports performance. Thus, by analyzing exercise-induced changes (D) in O2-Hb, H-Hb, and TSI, it is possible to identify central and peripheral exercise limitations, particularly when endurance training is the main component of physical fitness (e.g., running, cycling, triathlon, etc.). Addressing these factors is paramount for coaches and exercise physiologists to optimize athletic performance, incorporating training strategies focused on the primary exercise-limiting factors. This study outlines a protocol for utilizing wearables devices equipped with NIRS technology to analyze exercise changes in TSI, O2-Hb, and H-Hb, alongside cardiorespiratory variables typically registered in athletes during VO2&#8211;max tests. This approach offers a comprehensive method for identifying the primary systems involved in stopping exercise progression and sports performance improvement.

During the completion of a CPET, the symptoms of dyspnea, leg fatigue, and rate of perceived exertion (RPE) were reported in all subjects. The complementary use of the NIRS devices did not add any discomfort to the subjects&#39; sensation assessment. Also, we did not stop the CPET assessments by any risk event associated with excessive physiological stress.&#160; &#160;
We studied two competitive male cyclists recruited from a national cycling club. The inclusion criteria for this study were p...

This protocol integrates near-infrared spectroscopy (NIRS) technology to assess localized hematological and oxygenation changes at the prefrontal cortex, respiratory (m.Intercostales), and locomotor (m.Vastus Lateralis) muscles during cardiopulmonary exercise testing, enabling the identification of central and peripheral limiting factors affecting exercise performance.

Using Near-Infrared Spectroscopy Wearable Devices to Identify Central Versus Peripheral Limitations During Exercise

The gold standard to assess the aerobic capacity in physically active subjects and athletes is the maximal oxygen consumption test (VO2&#8211;max), which ...

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495 Views.  Pontificia Universidad Católica de Chile. This protocol integrates near-infrared spectroscopy (NIRS) technology to assess localized hematological and oxygenation changes at the prefrontal cortex, respiratory (m.Intercostales), and locomotor (m.Vastus Lateralis) muscles during cardiopulmonary exercise testing, enabling the identification of central and peripheral limiting factors affecting exercise performance.

Video: Using Near-Infrared Spectroscopy Wearable Devices to Identify Central Versus Peripheral Limitations During Exercise

In vivo Near Infrared Fluorescence (NIRF) Intravascular Molecular Imaging of Inflammatory Plaque, a Multimodal Approach to Imaging of Atherosclerosis

The vascular response to injury is a well-orchestrated inflammatory response triggered by the accumulation of macrophages within the vessel wall leading to an accumulation of lipid-laden intra-luminal plaque, smooth muscle cell proliferation and progressive narrowing of the vessel lumen. The formation of such vulnerable plaques prone to rupture underlies the majority of cases of acute myocardial infarction. The complex molecular and cellular inflammatory cascade is orchestrated by the recruitment of T lymphocytes and macrophages and their paracrine effects on endothelial and smooth muscle cells.1
Molecular imaging in atherosclerosis has evolved into an important clinical and research tool that allows in vivo visualization of inflammation and other biological processes. Several recent examples demonstrate the ability to detect high-risk plaques in patients, and assess the effects of pharmacotherapeutics in atherosclerosis.4 While a number of molecular imaging approaches (in particular MRI and PET) can image biological aspects of large vessels such as the carotid arteries, scant options exist for imaging of coronary arteries.2 The advent of high-resolution optical imaging strategies, in particular near-infrared fluorescence (NIRF), coupled with activatable fluorescent probes, have enhanced sensitivity and led to the development of new intravascular strategies to improve biological imaging of human coronary atherosclerosis.
Near infrared fluorescence (NIRF) molecular imaging utilizes excitation light with a defined band width (650-900 nm) as a source of photons that, when delivered to an optical contrast agent or fluorescent probe, emits fluorescence in the NIR window that can be detected using an appropriate emission filter and a high sensitivity charge-coupled camera. As opposed to visible light, NIR light penetrates deeply into tissue, is markedly less attenuated by endogenous photon absorbers such as hemoglobin, lipid and water, and enables high target-to-background ratios due to reduced autofluorescence in the NIR window. Imaging within the NIR 'window' can substantially improve the potential for in vivo imaging.2,5
Inflammatory cysteine proteases have been well studied using activatable NIRF probes10, and play important roles in atherogenesis. Via degradation of the extracellular matrix, cysteine proteases contribute importantly to the progression and complications of atherosclerosis8. In particular, the cysteine protease, cathepsin B, is highly expressed and colocalizes with macrophages in experimental murine, rabbit, and human atheromata.3,6,7 In addition, cathepsin B activity in plaques can be sensed in vivo utilizing a previously described 1-D intravascular near-infrared fluorescence technology6, in conjunction with an injectable nanosensor agent that consists of a poly-lysine polymer backbone derivatized with multiple NIR fluorochromes (VM110/Prosense750, ex/em 750/780nm, VisEn Medical, Woburn, MA) that results in strong intramolecular quenching at baseline.10 Following targeted enzymatic cleavage by cysteine proteases such as cathepsin B (known to colocalize with plaque macrophages), the fluorochromes separate, resulting in substantial amplification of the NIRF signal. Intravascular detection of NIR fluorescence signal by the utilized novel 2D intravascular NIRF catheter now enables high-resolution, geometrically accurate in vivo detection of cathepsin B activity in inflamed plaque.
In vivo molecular imaging of atherosclerosis using catheter-based 2D NIRF imaging, as opposed to a prior 1-D spectroscopic approach,6 is a novel and promising tool that utilizes augmented protease activity in macrophage-rich plaque to detect vascular inflammation.11,12 The following research protocol describes the use of an intravascular 2-dimensional NIRF catheter to image and characterize plaque structure utilizing key aspects of plaque biology. It is a translatable platform that when integrated with existing clinical imaging technologies including angiography and intravascular ultrasound (IVUS), offers a unique and novel integrated multimodal molecular imaging technique that distinguishes inflammatory atheromata, and allows detection of intravascular NIRF signals in human-sized coronary arteries.

In vivo Near Infrared Fluorescence NIRF Intravascular Molecular Imaging of Inflammatory Plaque, a Multimodal Approach to Imaging of Atherosclerosis

We detail a new near-infrared fluorescence (NIRF) catheter for 2-dimensional intravascular molecular imaging of plaque biology in vivo. The NIRF catheter can visualize key biological processes such as inflammation by reporting on the presence of plaque-avid activatable and targeted NIR fluorochromes. The catheter utilizes clinical engineering and power requirements and is targeted for application in human coronary arteries. The following research study describes a multimodal imaging strategy that utilizes a novel in vivo intravascular NIRF catheter to image and quantify inflammatory plaque in proteolytically active inflamed rabbit atheromata.

The vascular response to injury is a well-orchestrated inflammatory response triggered by the accumulation of macrophages within the vessel wall leading ...

Using Continuous Data Tracking Technology to Study Exercise Adherence in Pulmonary Rehabilitation

Pulmonary rehabilitation (PR) is an important component in the management of respiratory diseases. The effectiveness of PR is dependent upon adherence to exercise training recommendations. The study of exercise adherence is thus a key step towards the optimization of PR programs. To date, mostly indirect measures, such as rates of participation, completion, and attendance, have been used to determine adherence to PR. The purpose of the present protocol is to describe how continuous data tracking technology can be used to measure adherence to a prescribed aerobic training intensity on a second-by-second basis.
In our investigations, adherence has been defined as the percent time spent within a specified target heart rate range. As such, using a combination of hardware and software, heart rate is measured, tracked, and recorded during cycling second-by-second for each participant, for each exercise session. Using statistical software, the data is subsequently extracted and analyzed. The same protocol can be applied to determine adherence to other measures of exercise intensity, such as time spent at a specified wattage, level, or speed on the cycle ergometer. Furthermore, the hardware and software is also available to measure adherence to other modes of training, such as the treadmill, elliptical, stepper, and arm ergometer. The present protocol, therefore, has a vast applicability to directly measure adherence to aerobic exercise.

Pulmonary rehabilitation is widely recognized in the management of respiratory diseases. A key component to successful pulmonary rehabilitation is adherence to the recommended exercise training. The purpose of the present protocol is to describe how continuous data tracking technology can be used to precisely measure adherence to a prescribed aerobic training intensity.

Pulmonary rehabilitation (PR) is an important component in the management of respiratory diseases. The effectiveness of PR is dependent upon adherence to ...

Tissue-simulating Phantoms for Assessing Potential Near-infrared Fluorescence Imaging Applications in Breast Cancer Surgery

Inaccuracies in intraoperative tumor localization and evaluation of surgical margin status result in suboptimal outcome of breast-conserving surgery (BCS). Optical imaging, in particular near-infrared fluorescence (NIRF) imaging, might reduce the frequency of positive surgical margins following BCS by providing the surgeon with a tool for pre- and intraoperative tumor localization in real-time. In the current study, the potential of NIRF-guided BCS is evaluated using tissue-simulating breast phantoms for reasons of standardization and training purposes.
Breast phantoms with optical characteristics comparable to those of normal breast tissue were used to simulate breast conserving surgery. Tumor-simulating inclusions containing the fluorescent dye indocyanine green (ICG) were incorporated in the phantoms at predefined locations and imaged for pre- and intraoperative tumor localization, real-time NIRF-guided tumor resection, NIRF-guided evaluation on the extent of surgery, and postoperative assessment of surgical margins. A customized NIRF camera was used as a clinical prototype for imaging purposes.
Breast phantoms containing tumor-simulating inclusions offer a simple, inexpensive, and versatile tool to simulate and evaluate intraoperative tumor imaging. The gelatinous phantoms have elastic properties similar to human tissue and can be cut using conventional surgical instruments. Moreover, the phantoms contain hemoglobin and intralipid for mimicking absorption and scattering of photons, respectively, creating uniform optical properties similar to human breast tissue. The main drawback of NIRF imaging is the limited penetration depth of photons when propagating through tissue, which hinders (noninvasive) imaging of deep-seated tumors with epi-illumination strategies.

Near-infrared fluorescence (NIRF) imaging may improve therapeutic outcome of breast cancer surgery by enabling intraoperative tumor localization and evaluation of surgical margin status. Using tissue-simulating breast phantoms containing fluorescent tumor-simulating inclusions, potential clinical applications of NIRF imaging in breast cancer patients can be assessed for standardization and training purposes.

Inaccuracies in intraoperative tumor localization and evaluation of surgical margin status result in suboptimal outcome of breast-conserving surgery ...

Using an Ingestible Telemetric Temperature Pill to Assess Gastrointestinal Temperature During Exercise

Exercise results in an increase in core body temperature (Tc), which may reduce exercise performance and eventually can lead to the development of heat-related disorders. Therefore, accurate measurement of Tc during exercise is of great importance, especially in athletes who have to perform in challenging ambient conditions. In the current literature a number of methods have been described to measure the Tc (esophageal, external tympanic membrane, mouth or rectum). However, these methods are suboptimal to measure Tc during exercise since they are invasive, have a slow response or are influenced by environmental conditions. Studies described the use of an ingestible telemetric temperature pill as a reliable and valid method to assess gastrointestinal temperature (Tgi), which is a representative measurement of Tc. Therefore, the goal of this study was to provide a detailed description of the measurement of Tgi using an ingestible telemetric temperature pill. This study addresses important methodological factors that must be taken into account for an accurate measurement. It is recommended to read the instructions carefully in order to ensure that the ingestible telemetric temperature pill is a reliable method to assess Tgi at rest and during exercise.

This study describes an accurate, reliable and non-invasive technique to continuously measure gastrointestinal temperature during exercise. The ingestible telemetric temperature pill is suitable to measure gastrointestinal temperature in laboratory settings as well as in field based settings.

Exercise results in an increase in core body temperature (Tc), which may reduce exercise performance and eventually can lead to the development of ...

Combined Near-infrared Fluorescent Imaging and Micro-computed Tomography for Directly Visualizing Cerebral Thromboemboli

Direct thrombus imaging visualizes the root cause of thromboembolic infarction. Being able to image thrombus directly allows far better investigation of stroke than relying on indirect measurements, and will be a potent and robust vascular research tool. We use an optical imaging approach that labels thrombi with a molecular imaging thrombus marker&#160;&#8212; a Cy5.5 near-infrared fluorescent (NIRF) probe that is covalently linked to the fibrin strands of the thrombus by the fibrin-crosslinking enzymatic action of activated coagulation factor XIIIa during the process of clot maturation. A micro-computed tomography (microCT)-based approach uses thrombus-seeking gold nanoparticles (AuNPs) functionalized to target the major component of the clot: fibrin. This paper describes a detailed protocol for the combined in vivo microCT and ex vivo NIRF imaging of thromboemboli in a mouse model of embolic stroke. We show that in vivo microCT and fibrin-targeted glycol-chitosan AuNPs (fib-GC-AuNPs) can be used for visualizing both in situ thrombi and cerebral embolic thrombi. We also describe the use of in vivo microCT-based direct thrombus imaging to serially monitor the therapeutic effects of tissue plasminogen activator-mediated thrombolysis. After the last imaging session, we demonstrate by ex vivo NIRF imaging the extent and the distribution of residual thromboemboli in the brain. Finally, we describe quantitative image analyses of microCT and NIRF imaging data. The combined technique of direct thrombus imaging allows two independent methods of thrombus visualization to be compared: the area of thrombus-related fluorescent signal on ex vivo NIRF imaging vs. the volume of hyperdense microCT thrombi in vivo.

This protocol describes the application of combined near-infrared fluorescent (NIRF) imaging and micro-computed tomography (microCT) for visualizing cerebral thromboemboli. This technique allows the quantification of thrombus burden and evolution. The NIRF imaging technique visualizes fluorescently labeled thrombus in excised brain, while the microCT technique visualizes thrombus inside living animals using gold-nanoparticles.

Direct thrombus imaging visualizes the root cause of thromboembolic infarction. Being able to image thrombus directly allows far better investigation of ...

Skeletal Muscle Neurovascular Coupling, Oxidative Capacity, and Microvascular Function with 'One Stop Shop' Near-infrared Spectroscopy

Exercise represents a major hemodynamic stress that demands a highly coordinated neurovascular response in order to match oxygen delivery to metabolic demand. Reactive hyperemia (in response to a brief period of tissue ischemia) is an independent predictor of cardiovascular events and provides important insight into vascular health and vasodilatory capacity. Skeletal muscle oxidative capacity is equally important in health and disease, as it determines the energy supply for myocellular processes. Here, we describe a simple, non-invasive approach using near-infrared spectroscopy to assess each of these major clinical endpoints (reactive hyperemia, neurovascular coupling, and muscle oxidative capacity) during a single clinic or laboratory visit. Unlike Doppler ultrasound, magnetic resonance images/spectroscopy, or invasive catheter-based flow measurements or muscle biopsies, our approach is less operator-dependent, low-cost, and completely non-invasive. Representative data from our lab taken together with summary data from previously published literature illustrate the utility of each of these end-points. Once this technique is mastered, application to clinical populations will provide important mechanistic insight into exercise intolerance and cardiovascular dysfunction.

Skeletal Muscle Neurovascular Coupling, Oxidative Capacity, and Microvascular Function with &#039;One Stop Shop&#039; Near-infrared Spectroscopy

Here, we describe a simple, non-invasive approach using near-infrared spectroscopy to assess reactive hyperemia, neurovascular coupling and skeletal muscle oxidative capacity in a single clinic or laboratory visit.

Exercise represents a major hemodynamic stress that demands a highly coordinated neurovascular response in order to match oxygen delivery to metabolic ...

How to Administer Near-Infrared Spectroscopy in Critically ill Neonates, Infants, and Children

Near infrared spectroscopy (NIRS) calculates regional tissue oxygenation (rSO2) using the different absorption spectra of oxygenated and deoxygenated hemoglobin molecules. A probe placed on the skin emits light that is absorbed, scattered, and reflected by the underlying tissue. Detectors in the probe sense the amount of reflected light: this reflects the organ-specific ratio of oxygen supply and consumption - independent of pulsatile flow. Modern devices enable the simultaneous monitoring at different body sites. A rise or dip in the rSO2 curve visualizes changes in oxygen supply or demand before vital signs indicate them. The evolution of rSO2 values in relation to the starting point is more important for interpretation than are absolute values.
A routine clinical application of NIRS is the surveillance of somatic and cerebral oxygenation during and after cardiac surgery. It is also administered in preterm infants at risk for necrotizing enterocolitis, newborns with hypoxic ischemic encephalopathy and a potential risk of impaired tissue oxygenation. In the future, NIRS could be increasingly used in multimodal neuromonitoring, or applied to monitor patients with other conditions (e.g., after resuscitation or traumatic brain injury).

This protocol is designed to assist clinicians to measure regional tissue oxygenation at different body sites in infants and children. It can be used in situations where tissue oxygenation is potentially compromised, particularly during cardiopulmonary bypass, when using non-pulsatile cardiac-assist devices, and in critically ill neonates, infants and children.

Near infrared spectroscopy (NIRS) calculates regional tissue oxygenation (rSO2) using the different absorption spectra of oxygenated and deoxygenated ...

Near Infrared Photoimmunotherapy for Mouse Models of Pleural Dissemination

The efficacy of photoimmunotherapy can be evaluated more accurately with an orthotopic mouse model than with a subcutaneous one. A pleural dissemination model can be used for the evaluation of treatment methods for intrathoracic diseases such as lung cancer or malignant pleural mesothelioma.
Near-infrared photoimmunotherapy (NIR-PIT) is a recently developed cancer treatment strategy that combines the specificity of tumor-targeting antibodies with toxicity caused by a photoabsorber (IR700Dye) after exposure to NIR light. The efficacy of NIR-PIT has been reported using various antibodies; however, only a few reports have shown the therapeutic effect of this strategy in an orthotopic model. In the present study, we demonstrate an example of efficacy evaluation of the pleural disseminated lung cancer model, which was treated using NIR-PIT.

Near-infrared photoimmunotherapy (NIR-PIT) is an emerging cancer therapeutic strategy that utilizes an antibody-photoabsorber (IR700Dye) conjugate and NIR light to destroy cancer cells. Here, we present a method to evaluate the antitumor effect of NIR-PIT in a mouse model of pleural disseminated lung cancer and malignant pleural mesothelioma using bioluminescence imaging.

The efficacy of photoimmunotherapy can be evaluated more accurately with an orthotopic mouse model than with a subcutaneous one. A pleural dissemination ...

Measurement of Tissue Oxygenation Using Near-Infrared Spectroscopy in Patients Undergoing Hemodialysis

Near-infrared spectroscopy (NIRS) has recently been applied as a tool to measure regional oxygen saturation (rSO2), a marker of tissue oxygenation, in clinical settings including cardiovascular and brain surgery, neonatal monitoring and prehospital medicine. The NIRS monitoring devices are real-time and noninvasive, and have mainly been used for evaluating cerebral oxygenation in critically ill patients during an operation or intensive care. Thus far, the use of NIRS monitoring in patients with chronic kidney disease (CKD) including hemodialysis (HD) has been limited; therefore, we investigated rSO2 values in some organs during HD. We monitored rSO2 values using a NIRS device transmitting near-infrared light at 2 wavelengths of attachment. The HD patients were placed in a supine position, with rSO2 measurement sensors attached to the foreheads, the right hypochondrium and the lower legs to evaluate rSO2 in the brain, liver and lower leg muscles, respectively. NIRS monitoring could be a new approach to clarify changes in organ oxygenation during HD or factors affecting tissue oxygenation in CKD patients. This article describes a protocol to measure tissue oxygenation represented by rSO2 as applied in HD patients.

We present a protocol to measure regional oxygen saturation (rSO2) in hemodialysis (HD) patients by using a near-infrared spectroscopy monitor. The rSO2 value is an index of tissue oxygenation. This noninvasive and real-time monitoring could be useful for confirming changes in organ oxygenation during HD.

Near-infrared spectroscopy (NIRS) has recently been applied as a tool to measure regional oxygen saturation (rSO2), a marker of tissue oxygenation, in ...

Providing Visual Biofeedback Using Brightness Mode Ultrasound During a Golf Swing

Using ultrasound biofeedback in conjunction with verbal cueing can increase muscle thickness more than verbal cueing alone and may augment traditional rehabilitation techniques in an athletic, physically active population. Brightness mode (B-mode) ultrasound can be applied using frame-by-frame analysis synchronized with video to understand muscle thickness changes during these dynamic tasks. Visual biofeedback with ultrasound has been established in static positions for the muscles of the lateral abdominal wall. However, by securing the transducer to the abdomen using an elastic belt and foam block, biofeedback can be applied during more specific tasks prevalent in lifetime sports, such as golf. To analyze muscle activity during a golf swing, muscle thickness changes can be compared. The thickness must increase throughout the task, indicating that the muscle is more active. This methodology allows clinicians to immediately replay ultrasound videos for patients as a visual tool to instruct proper activity of the muscles of interest. For example, ultrasound can be used to target the external and internal obliques, which play an important role in swinging a golf club or any other rotational sport or activity. This methodology aims to increase oblique muscle thickness during the golf swing. Additionally, the timing of muscle contraction can be targeted by instructing the patient to contract the abdominal muscles at specific time points, such as the beginning of the downswing, with the goal of improving muscle firing patterns during tasks.

Brightness mode ultrasound can be used to provide visual biofeedback of the muscles of the lateral abdominal wall during a golf swing. Post-swing visual and verbal instruction can increase the muscle activation and timing of the external and internal obliques.

Using ultrasound biofeedback in conjunction with verbal cueing can increase muscle thickness more than verbal cueing alone and may augment traditional ...