Effect Of Exercise And Self-myofascial Release On The Stiffness Of The Gastrocnemius-Achilles Tendon Complex In Healthy Population

Background and objective:The Gastrocnemius-Achilles tendon(AT)complex is the largest and strongest muscle-tendon complex,which is the key to effective walking,running and jumping in humans.The stiffness of the gastrocnemius-AT complex can reflect the functional status of the gastrocnemius-AT complex.Previous studies usually used the displacement of the muscle-tendon complex to assess the overall stiffness of the gastrocnemius-AT complex,but the gastrocnemius and AT injuries usually occur at the specific regions of the gastrocnemius and AT,so the assessment of regional stiffness is important for the clinician.The Myoton PRO can measure the regional stiffness of the muscle-tendon complex,which may be useful for evaluating gastrocnemius stiffness and Achilles tendon stiffness.Exercise can cause changes in the muscle and tendon structure,which may affect the stiffness of the muscle-tendon complex.To investigate the effect of exercise on the stiffness of the gastrocnemius and AT,which can improve our understanding of the mechanical properties of the muscles-tendons complex and provide a reference for the accurate diagnosis of abnormalities.Self-myofascial release has recently been used in the clinic to relax the muscle and resolve the soft tissue dysfunction,but the effects of the self-myofascial release on muscle and tendon stiffness are unclear and need to be further explored.Based on that,three trials were conducted in this study.In study 1,we assessed the regional stiffness of the gastrocnemius and AT at different ankle positions using Myoton PRO,which is to verify the reliability of Myoton PRO;in study 2,we explored the effect of exercise on the stiffness of the gastrocnemius-Achilles tendon complex by comparing the stiffness of the gastrocnemius-Achilles tendon complex in amateur basketball players and the non-athletic general population;in study 3,we explored the effects of self-myofascial release on the stiffness of the gastrocnemius-Achilles tendon complex and the ankle dorsiflexion range of motion.Methods:Study 1: Thirty healthy young adults participated in this study.Rater A and Rater B measured the gastrocnemius and the regional Achilles tendon stiffness in the neutral position and 10° dorsiflexion of the ankle joint using the Myoton PRO within the same day(30 min interval),and rater A repeated the stiffness assessment after 5 days.Study 2: 20 amateur basketball players and 20 non-athletic general subjects were recruited for this study.Stiffness of the gastrocnemius-AT complex was assessed using Myoton PRO at neutral position and 10°dorsiflexion of the ankle joint in all participants.Study 3: Fifty healthy subjects were recruited and randomly divided into an intervention and a control group.the subjects in the intervention group received a single session of self-myofascial release,while the subjects in the control group performed a sedentary rest during the same intervention time.The stiffness of the medial,lateral gastrocnemius and AT in the dominant limb and the dorsiflexion range of motion of the ankle were assessed before and after the intervention,respectively.Results:Study 1: The intra-rater reliability(ICC≥0.83)and inter-rater reliability(ICC≥0.85)were good for the stiffness assessment at the medial,lateral gastrocnemius and AT,both in the neutral position and 10° dorsiflexion of the ankle;a significant modulation of the stiffness in the medial,lateral gastrocnemius and AT was obtained from the neutral position to the 10° dorsiflexion of ankle(P<0.05);the stiffness at AT-2 was higher than at AT-6(P<0.05)in both positions.Study 2: Our results showed a greater stiffness of the gastrocnemius-AT complex in amateur basketball players than that in healthy non-athletic subjects at neutral position and 10? dorsiflexion of the ankle(P<0.05).No significant difference in stiffness was found between the non-dominant and dominant lower limbs either in amateur basketball players or in generally healthy subjects(P>0.05).Study 3: For the foam roller and control groups,the between-group analysis revealed a statistically significant difference in gastrocnemius stiffness and ankle dorsiflexion ROM after intervention(P<0.05).Within-group analysis revealed an increase in ROM for the foam roller group after the intervention(P<0.05).In terms of soft tissue stiffness,there was a decrease in LG and MG stiffness in the foam roller group(P<0.05).Conclusion:The Myoton PRO is a reliable device for measuring the stiffness of the gastrocnemius and AT,the stiffness of the gastrocnemius and AT was increased with ankle dorsiflexion,and the stiffness of the AT was also nonuniform along the length of the tendon;The amateur basketball players exhibit significantly higher stiffness value in AT and gastrocnemius,this is possibly caused by repeated training effects.The symmetric stiffness of the AT and gastrocnemius exists both in amateur basketball players and generally healthy subjects;The single self-myofascial release on the calf is an effective method for decreasing the stiffness of the gastrocnemius and increasing ankle dorsiflexion ROM.