Author/Editor		Kacin, Alan; Drobnič, Matej; Marš, Tomaž; Miš, Katarina; Petrič, Maja; Weber, Daša; Grapar Žargi, Tina; Martinčič, David; Pirkmajer, Sergej
Title		Functional and molecular adaptations of quadriceps and hamstring muscles to blood flow restricted training in patients with ACL rupture
Type		članek
Publication year		2021
Volume		str. str.
ISSN		0905-7188 - Scandinavian journal of medicine & science in sports
Language		eng
Abstract		Effects of low-load blood flow restricted (LL-BFR) training remain unexplored in patients with ACL rupture. Our hypothesis was that LL-BFR training triggers augmented gains in knee muscle strength and size, which are paralleled with transcriptional responses of hypoxia-regulated genes and myokines. Eighteen volunteers (age 37.5 +- 9 yrs.) planned for ACL reconstruction, participated in the study. Twelve were divided between BFR group, performing 9 sessions of LL-BFR exercise, and SHAM-BFR group, performing equal training with sham vascular occlusion. Six subjects served as a control for muscle biopsy analysis. Cross-sectional area (CSA) and isokinetic strength of knee muscles were assessed before and after the training. Change in CSAquad was significantly (p<0.01) larger in BFR (4.9 %) compared to SHAM-BFR (1.3 %). Similarly, change in peak torque of knee extensors was significantly (p<0.05) larger in BFR (14 %) compared to SHAM-BFR (-1%). The decrease in fatigue index of knee extensors (6 %) was larger (p<0.01) in BFR than in SHAM-BFR (2 %). mRNA expression of HIF-1[alpha] in the vastus lateralis was reduced (p<0.05) in SHAM-BFR, while VEGF-A mRNA tended to be higher in BFR. The mRNA expression of myostatin and its receptor were reduced (p<0.05) in the semitendinosus after both types of training. Expression of IL-6, its receptors IL-6R[alpha] and gp130, as well as musclin were similar in control and training groups. In conclusion, our results show augmented strength and endurance of knee extensors but less of the flexors. LL-BFR training is especially effective for conditioning of knee extensors in this population.
Keywords		ACL rupture myokines muscle ischemia and hypoxia ruptura ACL miokini mišična ishemija in hipoksija