Analysis of the aerobic-anaerobic transition in elite cyclists during incremental exercise with the use of electromyography

Objectives-To investigate the validity and reliability of surface electromy ography (EMG) as a new non-invasive determinant of the metabolic response t o incremental exercise in elite cyclists. The relation between EMG activity and other more conventional methods for analysing the aerobic-anaerobic tr ansition such as blood lactate measurements lactate threshold (LT) and onse t of blood lactate accumulation (OBLA) and ventilatory parameters ventilato ry thresholds I and 2 VT1 and VT2 was studied. Methods-Twenty eight elite road cyclists (age 24 (4) years; Vo(2),MAX 69.9 (6. 4) ml/kg/min; values mean (SD) were selected as subjects. Each of them performed a ramp protocol (starting at 0 W with increases of 5 W every 12 s econds) on a cycle ergometer (validity study)). In addition, 15 of them per formed the same test twice (reliability study). During the tests, data on g as exchange and blood lactate levels mere collected to determine VT1, VT2 L T, and OBLA. The root mean squares of EMG signals (rms-E, MG) were recorded from both the vastus lateralis and the rectus femoris at each intensity us ing surface electrodes. Results-A two threshold response was detected in the rms-E,I IG recordings from both muscles in 90% of subjects, with two breakpoints, EMG(T1) and EMG (T2) at around 60-70% and 80-90% of Vo(2),MAX respectively. The results of the reliability study show ed no significant differences (p > 0.05) between mean values of EMG(T1) and EMG(T2) obtained in both tests. Furthermore, no significant differences (p > 0.05) existed between mean values of EMG(T1)M AX in the vastus lateralis and rectus femoris, and VT1, and LT (62.8 (14.5) and 69.0 (6.2) and 64.6 (6.4) and 68.7 (8.2)% of Vo(2)MAX respectively), o r between mean values of EMG(T2) in the vastus lateralis and rectus , femor is, and VT2 and OBLA (86.9 (9.0) and 88.0 (6.2) and 84.6 (6.5) and 87.7 (6. 4)% of vo(2)MAX respectively . Conclusions-rms-EMG may be a useful complementary non-invasive method for a nalysing the aerobic-anaerobic transition (ventilatory and lactate threshol ds) in elite cyclists.