OsteoVelocity - Effects of different Velocities in Resistance Training on Bone Mineral Density in Women: A Randomized Controlled Trial

Participants in the intervention groups 'high strain training' (HST) and 'low strain training' (LST) will participate in two supervised resistance training sessions per week for a duration of 6 months. Each session will last approximately 1 hour and 15 minutes. Training will be conducted in small groups with a maximum of 7 participants per group. A researcher will explain the exercises and all relevant parameters (e.g., movement velocity, range of motion, rest period, etc.) to the participants. Furthermore, a researcher will observe and provide corrective feedback to the participants during their performance. The feedback will encompass aspects such as posture, breathing, range of motion, tempo, and muscle engagement. Every mesocycle will begin with a two-week period of low-intensity exercise for learning purposes, followed by a five-week phase of moderate intensity and another five weeks of high-intensity training. The Borg Rating of Percieved Exertion Scale (RPE) and repetition ranges will be used to guide exercise intensity. Moderate intensity, approximately 65-75% of one repetition maximum (1 RM), will involve 10 to 15 repetitions, while high intensity, about 80-90% of 1 RM, will consist of 8 to 5 repetitions. The achieved weight and RPE will be recorded in the training log book for each exercise and set. Subsequently, the exercises will be modified. While the initial half of the intervention primarily incorporates less complex exercises on machines (e.g., leg press), the latter half will introduce more intricate movements (e.g., squats). Prior to each progressive resistance training session, there will be a general warm-up and a brief specific warm-up with drills to acclimate participants to the anticipated movement velocity. The intervention groups differ solely in the targeted movement velocity. The HST group will execute all exercises with an explosive concentric phase, a brief isometric hold at the turning point, and an eccentric phase at moderate velocity (X/1/2). The LST group will perform all exercises with an explosive concentric phase, a brief isometric hold at the turning point, and an extended eccentric phase (X/1/4). Both active groups will be instructed to execute the concentric phase at maximal velocity (X). The HST group will be directed to perform the eccentric phase at moderate velocity (2s), while the LST group will be instructed to execute a slow eccentric phase (4s). Session attendance will be recorded in the training logbook.