Skeletal muscle perfusion in electrically induced dynamic exercise in humans

Area of Science:

• Exercise Physiology
• Muscle Physiology
• Cardiovascular Physiology

Background:

• Understanding the physiological responses to different modes of muscle contraction is crucial for exercise science.
• Comparing voluntary contractions (VOL) with electrically induced muscle stimulation (EMS) provides insights into muscle કાર્યક્ષમતા and metabolic stress.

Purpose of the Study:

• To compare leg blood flow, blood pressure, and metabolic responses between voluntary and electrically induced knee extension exercises.
• To investigate the impact of contraction mode on oxygen uptake, substrate utilization, and metabolite efflux during dynamic exercise.

Main Methods:

• Six healthy men performed incremental one-legged dynamic knee extension tests.
• Exercise modes included voluntary contractions (VOL) and electrically induced contractions (EMS) up to 40 W.
• Measurements included pulmonary oxygen uptake, heart rate, mean arterial pressure, leg blood flow, and metabolite concentrations (lactate, ammonia, K+).

Main Results:

• Pulmonary oxygen uptake was identical between VOL and EMS.
• EMS led to higher ventilatory coefficient, heart rate, and mean arterial pressure compared to VOL.
• Leg blood flow, oxygen uptake, and conductance were similar, but lactate, ammonia, and K+ efflux were higher with EMS, especially at higher intensities.

Conclusions:

• Electrically induced muscle stimulation elicits a greater cardiovascular and metabolic stress than voluntary contractions at similar exercise intensities.
• Despite differences in cardiovascular and metabolic responses, muscle oxygen uptake and blood flow are comparable between VOL and EMS.
• The findings highlight distinct physiological demands imposed by voluntary versus electrically induced muscle contractions.