Abstract-ID....: 556
Title..........: Metabolic and neuromuscular fatigue in healthy women during a Wingate test

Authors........: Kokova, M., Pencheva, N., Kitanoska, D.
Institution....: South-West University
Department.....: Sports and Kinesitherapy
Country........: Bulgaria
Topic..........: Neuromuscular Physiology
Keyword I......: Kinesiological EMG
Keyword II.....: Exercise biochemistry
Keyword III....: Fatigue
Format(*)......: Oral

Introduction
The reasons for the anaerobic fatigue, the power limitation factors and the factors that could improve performance have been studied mostly on trained subjects. Such data on untrained subjects especially females are scarce and insufficient. The aim of this study is to evaluate the heart rate responses, blood lactate and glucose concentration changes, sEMG RMS and MPF profiles of six muscles involved in cycling as factors for the anaerobic performance and fatigue in healthy untrained women.

Methods
Nine women (24.0±3.4 years) performed a 30-s Wingate cycling test (load 0.075W/kg). Lactate and glucose levels were determined before and after the test. The sEMG activity of the following muscles of the right lower limb : vastus lateralis (VL), rectus femoris (RF), semitendinosus (ST), biceps femoris (BF), lateralis gastrocnemius (GL), and tibialis anterior (TA) was recorded before, during, and after the test. EMG analysis included RMS and ?%MPF determination.

Results
The values of the calculated anaerobic parameters were: maximum anaerobic power 2163±787 W, relative anaerobic power 5.7±1.4 W/kg, total anaerobic power 1454±466 kg-m/min and coefficient of anaerobic fatigue 55.9±16.9 %. Heart rate values (bmp) were: during warm-up - 160±24, end of test - 170±11, and recovery - 180±15. Lactate levels increased from 2.1±0.7 to 11.0±2.3 mmol/l, while glucose levels remained statistically unchanged (4.5±0.9 to 4.2±0.6). RMS values (normalized) at the beginning and at the end of the test were as follows: VL) 1.19±0.37 and 1.25±0.52; RF) 1.28±0.19 and 1.46±0.39; ST) 1.17±0.17 and 0.99±0.34; BF) 1.12±0.18 and 1.16±0.51; GL) 1.11±0.17 and 0.83±0.17; and TA) 0.95±0.16 and 0.96±0.34. ?%MPF values were: VL) -5.2±12.7; RF) +0.9±21.9; SM) -7.4±4.2; BF) -12.5±11.8; GL) -3.6±10.6; TA) +7.9±18.4 %.

Discussion
The results demonstrate a low anaerobic performance of the tested subjects. The fact that heart rate values rise significantly after the test indicates oxygen debt which is common for anaerobic tests (Weinstein et al., 1998). The significant change in lactate concentration (p=0.002) clearly shows the metabolic origin of fatigue under the tested conditions, although glucose levels reveal a lack of exercise-induced hypoglycemia. Moreover, no significant changes occurred in RMS and MPF (Gerdle et al., 2000, Öberg, 1995) showing that the neuromuscular fatigue is not a limiting factor for performance.

References
Gerdle B, Larsson B, Karlsson S. (2000). J Electromyogr Kinesiol, 10, 225-232.
Öberg T. (1995). J Electromyogr Kinesiol, 5 (4), 239-243.
Weinstein Y, Bediz C, Dotan R, Falk B (1998). Med Sci Sports Exerc, 30 (9), 1456-1460.

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