Zielstellung: Untersuchung von Validität und Reliabilität des Oberflächen-EMG als eine neue nichtinvasive Determinante der Stoffwechselreaktion auf ansteigende Belastung bei Eliteradsportlern und der Beziehung zu konventionellen Methoden zur Analyse des aerob-anaeroben Übergangs (Laktaschwelle/LT, Einsetzen der Laktatakkumulation /OBLA, Ventilationsschwelle/VT). Methode/Probanden: 28 Straßenradsportler absolvierten einen ansteigenden Fahrradergomtertest (Anstieg 5 W aller 12 sec), zur Überprüfung der Validität. 15 absolviertn den Test zweimal zur Überprüfung der Realibilität. Während der Tests wurden Daten zum Gasstoffwechsel und Blutlaktat gemessen, um VT1, VT2,LT und OBLA zu bestimmen. Außerdem wurdem EMG-Daten vomvastus lateralis und rects femoris erhoben. Ergebnis: Das EMG ist als zusätzliche nichtinvasive Methode zur Analyse des aerob-anaeroben Übergans bei Eliteradsportlern von Nutzen. OBJECTIVES: To investigate the validity and reliability of surface electromyography (EMG) as a new non-invasive determinant of the metabolic response to incremental exercise in elite cyclists. The relation between EMG activity and other more conventional methods for analysing the aerobic-anaerobic transition such as blood lactate measurements (lactate threshold (LT) and onset of blood lactate accumulation (OBLA)) and ventilatory parameters (ventilatory thresholds 1 and 2 (VT1 and VT2)) was studied. METHODS: Twenty eight elite road cyclists (age 24 (4) years; VO2MAX 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 seconds) on a cycle ergometer (validity study). In addition, 15 of them performed the same test twice (reliability study). During the tests, data on gas exchange and blood lactate levels were collected to determine VT1, VT2, LT, and OBLA. The root mean squares of EMG signals (rms-EMG) were recorded from both the vastus lateralis and the rectus femoris at each intensity using surface electrodes. RESULTS: A two threshold response was detected in the rms-EMG recordings from both muscles in 90% of subjects, with two breakpoints, EMGT1 and EMGT2, at around 60-70% and 80-90% of VO2MAX respectively. The results of the reliability study showed no significant differences (p > 0.05) between mean values of EMGT1 and EMGT2 obtained in both tests. Furthermore, no significant differences (p > 0.05) existed between mean values of EMGT1, 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 VO2MAX respectively), or between mean values of EMGT2, in the vastus lateralis and rectus femoris, and VT2 and OBLA (86.9 (9.0) and 88.0 (6.2) and 84.6 (6.5) and 87.7 (6.4)% of VO2MAX respectively). CONCLUSION: rms-EMG may be a useful complementary non-invasive method for analysing the aerobic-anaerobic transition (ventilatory and lactate thresholds) in elite cyclists.
© Copyright 1999 British Journal of Sports Medicine. BMJ Publishing Group Ltd of the BMA. Alle Rechte vorbehalten.