Sequential use of low-intensity strength training with blood flow restriction followed by high-intensity strength training compared to purely high-intensity strength training: Effects on maximum strength, muscle cross-sectional area, tendon cross-sectional area, tendon stiffness, and muscle activation.

The goal of this project is to investigate the sequential application of BFRT (Blood Flow Restriction Training) for 8 weeks followed by high-load strength training for 2 weeks, compared to solely high-load strength training (8+2 weeks) on the lower extremities in healthy adults (n=40; ages 45-60). Various measurement parameters will be recorded before and after the first 8 weeks of training, as well as after the tenth week. In addition to gains in maximum strength and muscle cross-sectional area, the cross-sectional area and stiffness of the quadriceps tendon will be assessed. Aspects of neuromuscular activation will be examined using electromyography and the twitch interpolation technique to assess neuromuscular activation. The study provides important basic data, which enables a better understanding of future clinical application fields. For example, it is known that neural adaptations to strength training occur especially when trained with high mechanical loads. Since it is also known that neural adaptations with high loads occur very quickly, the sequential use of low-intensity BFRT followed by high-intensity strength training is of particular interest. Thus, BFRT could result in strong increases in muscle cross-sectional area, and the subsequent high-intensity training could compensate for the reduced neural adaptations. In addition, tendon adaptations (tendon cross-sectional area and stiffness) will be studied in this project. These are of interest because tendons generally adapt slower than the associated muscles, and these tendon adaptations occur especially when the tendon is exposed to high loads. Should BFRT result in significant strength gains but not trigger adaptations in the tendon, this could be a risk factor for tendon overuse, arguing against its widespread use in clinical practice.