Changes in the Plantar Flexion Torque of the Ankle and in the Morphological Characteristics and Mechanical Properties of the Achilles Tendon after 12-Week Gait Retraining

Deng

Xiao

et al. 2021

IJERPH

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Background: Patients with Achilles tendon (AT) injuries are often engaged in sedentary work because of decreasing tendon vascularisation. Furthermore, men are more likely to be exposed to AT tendinosis or ruptures. These conditions are related to the morphological and mechanical properties of AT, but the mechanism remains unclear. This study aimed to investigate the effects of sex on the morphological and mechanical properties of the AT in inactive individuals. Methods: In total, 30 inactive healthy participants (15 male participants and 15 female participants) were recruited. The AT morphological properties (cross-sectional area, thickness, and length) were captured by using an ultrasound device. The AT force–elongation characteristics were determined during isometric plantarflexion with the ultrasonic videos. The AT stiffness was determined at 50%–100% maximum voluntary contraction force. The AT strain, stress, and hysteresis were calculated. Results: Male participants had 15% longer AT length, 31% larger AT cross-sectional area and 21% thicker AT than female participants (p < 0.05). The plantarflexion torque, peak AT force, peak AT stress, and AT stiffness were significantly greater in male participants than in female participants (p < 0.05). However, no significant sex-specific differences were observed in peak AT strain and hysteresis (p > 0.05). Conclusions: In physically inactive adults, the morphological properties of AT were superior in men but were exposed to higher stress conditions. Moreover, no significant sex-specific differences were observed in peak AT strain and hysteresis, indicating that the AT of males did not store and return elastic energy more efficiently than that of females. Thus, the mechanical properties of the AT should be maintained and/or improved through physical exercise.

Section: Discussioncontrasting

confidence: 75%

Sex Differences in the Morphological and Mechanical Properties of the Achilles Tendon

Deng

Xiao

et al. 2021

IJERPH

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“…Ueno et al [ 38 ] found that a longer AT length is positively correlated with energy cost during submaximal running as it could store and return more elastic energy from the ground reaction force compared with a shorter AT. The greater AT CSA of males contributes to the potentially greater MG strength of males, as indicated by the higher AT force in males than in females [ 47 ]. Thus, the higher mechanical loads that can be exerted on the AT mean a greater adaptive hypertrophy because of increased collagen turnover in males.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, the higher mechanical loads that can be exerted on the AT mean a greater adaptive hypertrophy because of increased collagen turnover in males. The results implied higher load-resisting capacities because the stress, a risk factor of AT injuries, is lower if equal force is exerted on the AT [ 47 ]. This result might suggest that the AT injury rate of males is probably higher than that of females.…”

Section: Discussionmentioning

confidence: 99%

Gender Difference in Architectural and Mechanical Properties of Medial Gastrocnemius–Achilles Tendon Unit In Vivo

Deng

Xiao

et al. 2021

Life

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This study aims to explore whether gender differences exist in the architectural and mechanical properties of the medial gastrocnemius–Achilles tendon unit (gMTU) in vivo. Thirty-six healthy male and female adults without training experience and regular exercise habits were recruited. The architectural and mechanical properties of the gMTU were measured via an ultrasonography system and MyotonPRO, respectively. Independent t-tests were utilized to quantify the gender difference in the architectural and mechanical properties of the gMTU. In terms of architectural properties, the medial gastrocnemius (MG)’s pennation angle and thickness were greater in males than in females, whereas no substantial gender difference was observed in the MG’s fascicle length; the males possessed Achilles tendons (ATs) with a longer length and a greater cross-sectional area than females. In terms of mechanical properties, the MG’s vertical stiffness was lower and the MG’s logarithmic decrement was greater in females than in males. Both genders had no remarkable difference in the AT’s vertical stiffness and logarithmic decrement. Gender differences of individuals without training experience and regular exercise habits exist in the architectural and mechanical properties of the gMTU in vivo. The MG’s force-producing capacities, ankle torque, mechanical efficiency and peak power were higher in males than in females. The load-resisting capacities of AT were greater and the MG strain was lesser in males than in females. These findings suggest that males have better physical fitness, speed and performance in power-based sports events than females from the perspective of morphology and biomechanics.

“…A more appropriate training program would be a combined intervention to enhance both the intrinsic and extrinsic foot muscles (i.e., active subsystem) of the foot core system, which can simultaneously improve foot function in static posture and dynamic activities ( McKeon et al, 2015 ). Accordingly, previous gait retraining studies have begun to incorporate foot core exercise to reduce the risk of injury in participants when the strike pattern suddenly changes ( Warne et al, 2014 ; Deng et al, 2020 ; Zhang et al, 2021 ). Nevertheless, few studies have investigated the effect of this combined intervention on the MLA at a static position and during running.…”

Section: Introductionmentioning

confidence: 99%

Effects of a 12-week gait retraining program combined with foot core exercise on morphology, muscle strength, and kinematics of the arch: A randomized controlled trial

Shen

Front. Bioeng. Biotechnol.

Cui

et al. 2022

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Objective: This study aims to explore the effects of a 12-week gait retraining program combined with foot core exercise on arch morphology, arch muscles strength, and arch kinematics.Methods: A total of 26 male recreational runners with normal arch structure who used rear-foot running strike (RFS) were divided into the intervention group (INT group) and control group (CON group) (n = 13 in each group). The INT group performed a 12-week forefoot strike (FFS) training combined with foot core exercises. The CON group did not change the original exercise habit. Before and after the intervention, the arch morphology, as well as the strength of hallux flexion, lesser toe flexion, and the metatarsophalangeal joint (MPJ) flexors were measured in a static position, and changes in the arch kinematics during RFS and FFS running were explored.Results: After a 12-week intervention, 1) the normalized navicular height increased significantly in the INT group by 5.1% (p = 0.027, Cohen’s d = 0.55); 2) the hallux absolute flexion and relative flexion of the INT group increased significantly by 20.5% and 21.7%, respectively (p = 0.001, Cohen’s d = 0.59; p = 0.001, Cohen’s d = 0.73), the absolute and relative strength of the MPJ flexors of the INT group were significantly improved by 30.7% and 32.5%, respectively (p = 0.006, Cohen’s d = 0.94; p = 0.006, Cohen’s d = 0.96); 3) and during RFS, the maximum arch angle of the INT group declined significantly by 5.1% (p < 0.001, Cohen’s d = 1.49), the arch height at touchdown increased significantly in the INT group by 32.1% (p < 0.001, Cohen’s d = 1.98).Conclusion: The 12-week gait retraining program combined with foot core exercise improved the arch in both static and dynamic positions with a moderate to large effect size, demonstrating the superiority of this combined intervention over the standalone interventions. Thus, runners with weak arch muscles are encouraged to use this combined intervention as an approach to enhance the arch.