# NIRS-EMG for Clinical Applications: A Systematic Review
## 4 NIRS-EMG: Review of Studies in Clinical Practice
### Nirs and Emg Hh  
For the interested reader, a comprehensive review describing NIRS instruments for monitoring muscles can be found in a recent review by [PERSON] et al. [5]. Furthermore, in Section 3.1, a list of the devices and sensors for the different NIRS modalities was presented. In the same line, we do not provide an overview of the countless commercial and prototype EMG sensors available, as well as the possible technical set-ups and aspects of the recording, for which relevant works are already available in the field [85]. Instead, according with the purpose of this review, we present, in chronological order, the works we found where integrated NIRS-EMG systems were presented or employed. In 2008, a rehabilitation strategy which presented the idea of the integration of sensors for upper limb rehabilitation after stroke was outlined [86]. The first paper where a physical prototype was presented supporting this concept was very recent and only dates back to 2010, when [PERSON] et al. proposed a novel sensor in which the two techniques were combined [87]. As a main application, they specified the detection of muscle exertion for the real-time control of assistive devices. In 2015, [PERSON] et al. proposed a new layered sensor for simultaneous measurements of EMG, mechanomyography (MMG), and CW-NIRS, which was tested during a cuff occlusion [88]. In 2016, [PERSON] et al. developed an integrated 64-channel portable CW-NIRS instrument with physiological sensors [89]. These sensors were: High-resolution EMG, electrocardiography (ECG), electrooculography (EOG), and electroencephalography (EEG) sensors. The device was tested electronically, on phantomsand during in-vivo measurements, on muscle. [PERSON] et al. presented a multi-channel and wireless EMG-NIRS (CW) sensor system [90]. It was suggested in the context of prosthetic manipulation, even if, in the paper, it was characterized from an electronic point of view on a healthy subject performing incremental isometric exercises. The same device was, then, applied on 13 able-bodied male subjects and 3 transradial amputees for improving the control of upper-limb prostheses [91]. The most recent example was that from [PERSON] et al., in 2018 [92]. The main focus of their work was to create a prototype system, comprised of a tilt table and a lower body negative pressure (LBNP) chamber, for space medicine application. Inside the chamber, they integrated a sub-system for monitoring the physiological parameters of subjects undergoing tilt and pressure tests. The monitored parameters included ECG, pulse oximetry, EMG, skin conductance, blood pressure, body temperature, impedance reography, EEG, capnography, NIRS, and arterial pressure.  
In a review by [PERSON] et al., an overview of the wearable equipment for giving biofeedback in the physically active population has been provided [6]. In their Table 5, we find a list of portable NIRS device with the addition of physiological sensors. They cited two commercial instruments in which EMG sensors were integrated: the NIRSPORT from NIRx and Mobita from TMSi, both based on CW-NIRS.