Near Infrared Spectroscopy Measurements Of Muscle Metabolism In Elite Short-track Speed Skaters During On-ice Race Simulation

Abstract

PURPOSE: To gain real-time information pertaining to the concentration and oxygenation changes of haemoglobin in the vastus lateralis muscle during short track race simulation, by using the wireless capabilities of a recently developed portable NIRS device. METHODS: A dual wavelength NIRS device was placed on both the right and left leg of each subject, positioned midway between the greater trachanter of the femur and the lateral epicondyl. Subjects were 6 male elite short track speed skaters, all of whom were members of the Great Britain Olympic squad (age: 22 ± 3 years, height: 172.6 ± 11.79 cm, mass: 70.75 ± 12.43 kg, mid-thigh skin fold thickness: 6.97 ± 1.3 mm). Each subject completed a race simulation for 2 Olympic race distances: 500m and 1500m. Changes in muscle oxyhaemoglobin, muscle deoxyhaemoglobin, heart rate, global oxygen consumption (VO2) and a video record were analysed for each race. RESULTS: Immediately following the start of 500m race there was an initial drop from baseline in total haemoglobin concentration as a consequence of constriction of the muscle (-5.96 ±1.6 μM). However, by the end of the race simulation, muscle haemoglobin concentration had increased significantly (+9.52 ± 8.69 μM), presumably consequent to a change in vessel diameter and blood flow. Significant differences between the right and left leg were seen at different phases of the lap. Most notably, during the 500m race, when skaters travel around the apex of the bend supported solely on the right leg ('hang' phase), the right leg shows a rapid drop in total blood haemoglobin, -6.7 ±1.06 μM, whereas the left leg shows no such drop, +2.1 ±0.6 μM. During the 1500 m athletes make less use of the hang phase, and this difference between right and left leg is not apparent. CONCLUSIONS: This is the first time that real-time NIRS measurements have been made of elite short track speeds skaters under on-ice race simulation conditions. The wireless capability of the NIRS device used allowed real-time monitoring of muscle oxygenation and blood volume. The difference in skating styles during events of different distances, reflected in changes in oxyhaemoglobin and deoxyhaemoglobin concentrations, is likely to map onto key haemodynamic (blood flow) and metabolic (oxygen consumption) parameters.