Effects of vibration training and resistive exercise on fatigability of leg muscles (Pilot-Vibration-Study)

Kurzfassung

Exercise countermeasures against the losses of leg muscle and bone mass during long term space flight still need to be improved in terms of safety and efficiency. In a recent bed rest study a combination of resistive strength training plus whole body vibration was successfully applied to counteract leg muscle atrophy (Blottner et al. 2006, Eur J Appl Physiol). However, the combined training was tested against bed rest without training, and resistive training alone is also known to efficiently counteract muscle loss during bed rest (Alkner & Tesch 2004, Eur J Appl Physiol). In our field study, we test the hypothesis that a combination of whole body vibration plus resistive training in terms of knee bends is a superior method to reduce muscle fatigability in comparison to knee bends only. It is examined whether reduced muscle fatigability can be observed in subsequent training sessions. Fatigue is determined by EMG and fatigue related blood parameters. Two groups, each consisting of 20 non athletic healthy male subjects, either perform whole body vibration training (Galileo 900, Novotec, Pfortzheim, Germany) with a frequency of 20Hz and an amplitude of 2-4mm plus knee bends or knee bends only as control. Training is performed on 5 consecutive days. Each training session consists of 10 exercise periods in which subjects perform 10 knee bends within 1 min. In between the exercise bouts, subjects rest for 1 minute on a chair. In both groups, subjects are extra loaded by about 10% of their individual body weight. EMG activity is recorded (MyoSystem 1400, Noraxon, USA) on day 1, 3, and 5 of the training week of the m. rectus femoris and the m. gastrocnemius lateralis by bipolar electrodes on both legs. The relative increase in EMG amplitude and the decrease in median frequency are evaluated as parameters of fatigue. Capillary blood samples are taken before and after training every day from which lactate and the acid-base status are analyzed. From the results of this study we expect a better understanding whether and how vibration can be added to resistive training to improve training effects in leg muscles of non athletic subjects in comparison to resistive training alone. In July, the measurements and evaluation of this study will be finished so that the results will be presented at the Medicine and Mobility Congress 2006 in Berlin.