Abstract
The development of an underwater near-infrared spectroscopy (uNIRS) device has enabled previously unattainable measurements of peripheral muscle hemodynamics and oxygenation to be taken within the natural aquatic environment. The purposes of this study were (i) to trial the use of uNIRS, in a real world training study, and (ii) to monitor the effects of a swim training program upon muscle oxygenation status in short distance swimming. A total of 14 junior club level swimmers completed a repeated swim sprint test before and after an eight week endurance training program. A waterproof, portable Near-Infrared Spectroscopy device was attached to the vastus lateralis. uNIRS successfully measured changes in muscle oxygenation and blood volume in all individuals; rapid sub-second time resolution of the device was able to demonstrate muscle oxygenation changes during the characteristic swim movements. Post training heart rate recovery and swim performance time were significantly improved. uNIRS data also showed significant changes. A larger rise in deoxyhemoglobin during individual sprints suggested training induced an increase in muscle oxygen extraction; a faster recovery time for muscle oxygenation suggested positive training induced changes and significant changes in muscle blood flow also occur. As a strong correlation was seen between an increased reoxygenation rate and an improved swim performance time, these findings support the use of uNIRS as a new performance analysis tool in swimming.
Highlights
Near-Infrared Spectroscopy (NIRS) facilitates non-invasive monitoring of changes in the concentration of oxyhemoglobin + oxymyoglobin (O2Hb + O2Mb) and deoxyhemoglobin + deoxymyoglobin (HHb + HMb) chromophores within the small blood vessels, capillaries and intracellular sites of O2 transport and O2 uptake (Mancini et al, 1994; Grassi et al, 2003)
A waterproof, portable NIRS device was attached to the dominant leg, vastus lateralis to provide a non-invasive measure of muscle oxygenation throughout the swim test (Jones, Dat & Cooper, 2014)
O2Hb + O2Mb and total muscle hemoglobin concentration (tHb) reach a plateau after ∼20 s during each swim sprint, whereas HHb + HMb amplitude continues to rise throughout the swim period, with a peak occurring at the end of the 100 m
Summary
Near-Infrared Spectroscopy (NIRS) facilitates non-invasive monitoring of changes in the concentration of oxyhemoglobin + oxymyoglobin (O2Hb + O2Mb) and deoxyhemoglobin + deoxymyoglobin (HHb + HMb) chromophores within the small blood vessels, capillaries and intracellular sites of O2 transport and O2 uptake (Mancini et al, 1994; Grassi et al, 2003). Beer–Lambert Law derived trend changes in muscle deoxyhemoglobin concentration have been suggested to provide information related to muscle oxygen extraction, whereas. As a completely non-invasive optical method with strong signal to noise ratio and millisecond time resolution NIRS is readily translatable to extreme and challenging environments. In principle there is no reason why muscle NIRS measurements should not be transferable to all aquatic environments
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