Cutaneous microvascular functional assessment during exercise: a novel approach using laser speckle contrast imaging

Area of Science:

• Physiology
• Biomedical Engineering

Background:

• Cardiovascular diseases are often detected during exercise, highlighting the importance of studying cutaneous blood flow (CBF) dysfunction.
• Laser speckle contrast imaging (LSCI) is a non-contact, real-time method for assessing resting CBF.

Purpose of the Study:

• To evaluate the efficacy of LSCI for studying CBF during cycling exercise.
• To assess the impact of a novel signal processing technique on LSCI data quality during exercise.

Main Methods:

• LSCI was used to record baseline CBF and peak post-occlusive reactive hyperemia (PORH) from the forearm in nine healthy subjects during rest and cycling exercise (80 W at 70 rpm).
• A signal processing technique was applied to remove movement artifacts from LSCI data, and cross-correlation coefficients were calculated to assess signal quality.
• Cutaneous vascular conductance (CVC) was calculated as laser speckle perfusion units (LSPU) per mmHg.

Main Results:

• Signal processing significantly improved the cross-correlation of LSCI traces during exercise (r=0.683) compared to raw data (r=0.226).
• Peak PORH during cycling exercise was significantly reduced (0.38 LSPU/mmHg) compared to the non-exercise phase (0.69 LSPU/mmHg, p < 0.01).
• Baseline CBF showed no significant difference between rest and exercise conditions.

Conclusions:

• LSCI, with appropriate signal processing, is a valuable tool for investigating dynamic changes in CBF during exercise.
• Upper limb peak PORH is attenuated during lower limb cycling exercise, suggesting complex central and peripheral regulatory mechanisms.
• Further research is needed to explore these mechanisms in healthy and cardiovascular disease populations.