Near infrared spectroscopy (NIRS) performed during loaded breathing and hand grip exercise
Details on this research can be found at Shadgan et al. Respiratory Physiology and Neurobiology 2011; 178(2):202-209. http://dx.doi.org/10.1016/j.resp.2011.06.001. and Basoudan, et al. Eur J Appl Physiol (2016) 116: 841. doi:10.1007/s00421-016-3334-x.
- We examined muscle oxygenation, deoxygenation and blood volume in the sternocleidomastoid, an accessory muscle of inspiration during progressive inspiratory threshold loading (ITL) in healthy subjects using near-infrared spectroscopy.
- We compared the sternocleidomastoid response to other respiratory muscles (parasternal and intercostal muscles) and a quiescent limb muscle (vastus lateralis).
- During progressive loading, the sternocleidomastoid showed the greatest changes with significant increases in deoxygenated and total hemoglobin.
- Our data indicates that the sternocleidomastoid is an important muscle that is recruited at higher loads of breathing.
- A second set of experiments during hypoxia (Basoudan et al) demonstrated that the sternocleidomastoid is the most vulnerable to deoxygenation while breathing hypoxia (15% O2).
The most recent set of experiments that examined forearm muscles during handgrip exercise while breathing hypoxia (12% O2) demonstrated that the muscle deoxygenates moreso during hypoxia and this deoxygenation is not detected by an oximeter that measures blood oxygen levels.