Sakai S1, Urabe Y1, Morikawa M1, Sasadai J1, Maeda N1
1Hiroshima University, Graduate School of Biomedical and Health Sciences, Department of Sports Rehabilitation, Hiroshima, Japan
Background: Cyclic stretching reported by McNair et al. (2001) is the constant velocity stretching. Our previous studies have shown that the cyclic stretching effected positively for physical performance (e.g. range of motion; ROM, muscle strength, and dynamic postural balance) (Maeda et al., 2015; Tsutsumi et al., 2016; Morita et al., 2017). On the other hand, those studies have not investigated the effect of cyclic stretching for muscle and tendon hardness. Muscle and tendon hardness were considered to influence physical performance. It has reported that muscle hardness became harder and muscle strength decreased after exercise (Murayama et al., 2000). Further, tendon hardness and isometric muscle strength have found a positive correlation in the previous study (Kubo et al., 2010). However, the acute effect of cyclic stretching for muscle and tendon hardness was unclear.
Purpose: This study aimed to investigate the acute effect of cyclic stretching on muscle and tendon hardness measured by ultrasound real-time tissue elastography and contribute to clarifying an effect of cyclic stretching scientifically.
Methods: Seven healthy men participated in this study (mean, 23.8 ± 2.1 years old, height: 172.5 ± 2.7 cm, weight: 64.1 ± 9.9 kg). Cyclic stretching performed as follows; ankle joint was cycled at 10°s-1 from 10°of plantarflexion to 80% of maximum dorsiflexion using Biodex System 3 (Biodex Medical Systems, USA) for 2 minutes. In this study, the medial gastrocnemius muscle belly and Achilles tendon hardness (coupler/ muscle, tendon), dorsiflexion ROM (°), and maximal voluntary isometric plantar flexion (MVIP) torque (Nm/kg) were measured before and after cyclic stretching. Medial gastrocnemius muscle and Achilles tendon hardness were measured using ultrasound real-time tissue elastography (Noblus, Hitachi, Japan). ROM and MVIP were measured using Biodex System 3. Paired t-test was performed for statistical analysis, and the significance level was set at 0.05.
Results: After cyclic stretching, the significant decrease in medial Gastrocnemius muscle hardness (31%) and increase in ROM (3.4 ± 1.3 °) were found compared to before stretching (p 0.05; p 0.01). No significant difference was found in Achilles tendon hardness and MVIP between before and after cyclic stretching (p = 0.31; p = 0.06).
Conclusion(s): Cyclic stretching decreased muscle hardness and improved ankle dorsiflexion range of motion. However, tendon hardness and muscle strength maintained after cyclic stretching. This result indicated that increased ROM was caused by decreased muscle hardness. The tendon has a role to transmit the muscle contraction to a bone. Therefore, the hard tendon could transmit the muscle contraction to a bone more effectively in isometric contraction. It was suggested that non-reduction of MVIP was caused by non-decrease of Achilles tendon hardness after cyclic stretching. The results of this study revealed the effect of cyclic stretching on the muscle and tendon hardness. The authors need to compare between cyclic stretching and another stretching method in the next study.
Implications: This study showed the influence of cyclic stretching on the muscle and tendon hardness. It would contribute to the development of stretching method for sports performance enhancement.
Keywords: Cyclic stretching, Muscle hardness, Tendon hardness
Funding acknowledgements: We have no funding acknowledgment in this study.
Purpose: This study aimed to investigate the acute effect of cyclic stretching on muscle and tendon hardness measured by ultrasound real-time tissue elastography and contribute to clarifying an effect of cyclic stretching scientifically.
Methods: Seven healthy men participated in this study (mean, 23.8 ± 2.1 years old, height: 172.5 ± 2.7 cm, weight: 64.1 ± 9.9 kg). Cyclic stretching performed as follows; ankle joint was cycled at 10°s-1 from 10°of plantarflexion to 80% of maximum dorsiflexion using Biodex System 3 (Biodex Medical Systems, USA) for 2 minutes. In this study, the medial gastrocnemius muscle belly and Achilles tendon hardness (coupler/ muscle, tendon), dorsiflexion ROM (°), and maximal voluntary isometric plantar flexion (MVIP) torque (Nm/kg) were measured before and after cyclic stretching. Medial gastrocnemius muscle and Achilles tendon hardness were measured using ultrasound real-time tissue elastography (Noblus, Hitachi, Japan). ROM and MVIP were measured using Biodex System 3. Paired t-test was performed for statistical analysis, and the significance level was set at 0.05.
Results: After cyclic stretching, the significant decrease in medial Gastrocnemius muscle hardness (31%) and increase in ROM (3.4 ± 1.3 °) were found compared to before stretching (p 0.05; p 0.01). No significant difference was found in Achilles tendon hardness and MVIP between before and after cyclic stretching (p = 0.31; p = 0.06).
Conclusion(s): Cyclic stretching decreased muscle hardness and improved ankle dorsiflexion range of motion. However, tendon hardness and muscle strength maintained after cyclic stretching. This result indicated that increased ROM was caused by decreased muscle hardness. The tendon has a role to transmit the muscle contraction to a bone. Therefore, the hard tendon could transmit the muscle contraction to a bone more effectively in isometric contraction. It was suggested that non-reduction of MVIP was caused by non-decrease of Achilles tendon hardness after cyclic stretching. The results of this study revealed the effect of cyclic stretching on the muscle and tendon hardness. The authors need to compare between cyclic stretching and another stretching method in the next study.
Implications: This study showed the influence of cyclic stretching on the muscle and tendon hardness. It would contribute to the development of stretching method for sports performance enhancement.
Keywords: Cyclic stretching, Muscle hardness, Tendon hardness
Funding acknowledgements: We have no funding acknowledgment in this study.
Topic: Sport & sports injuries
Ethics approval required: Yes
Institution: Hiroshima University
Ethics committee: The Institutional Review Board of the Graduate School
Ethics number: E-341
All authors, affiliations and abstracts have been published as submitted.
