Abstract
PurposeThe present study investigated whether neuromuscular electrical stimulation for 20 min twice a day with an electrode placed over the soleus muscle and nutritional supplementation with 19 g of protein rich lupin seeds can reduce the loss in volume and strength of the human calf musculature during long term unloading by wearing an orthotic unloading device.MethodsThirteen healthy male subjects (age of 26.4 ± 3.7 years) wore a Hephaistos orthosis one leg for 60 days during all habitual activities. The leg side was randomly chosen for every subject. Six subjects only wore the orthosis as control group, and 7 subjects additionally received the countermeasure consisting of neuromuscular electrical stimulation of the soleus and lateral gastrocnemius muscles and lupin protein supplementation. Twenty-eight days before and on the penultimate day of the intervention cross-sectional images of the calf muscles were taken by magnetic resonance imaging (controls n = 5), and maximum voluntary torque (controls n = 6) of foot plantar flexion was estimated under isometric (extended knee, 90° knee flexion) and isokinetic conditions (extended knee), respectively.ResultsAfter 58 days of wearing the orthosis the percentage loss of volume in the entire triceps surae muscle of the control subjects (-11.9 ± 4.4%, mean ± standard deviation) was reduced by the countermeasure (-3.5 ± 7.2%, p = 0.032). Wearing the orthosis generally reduced plantar flexion torques values, however, only when testing isometric contraction at 90° knee ankle the countermeasure effected a significantly lower percentage decrease of torque (-9.7 ± 7.2%, mean ± SD) in comparison with controls (-22.3 ± 11.2%, p = 0.032).ConclusionUnloading of calf musculature by an orthotic device resulted in the expected loss of muscle volume and maximum of plantar flexion torque. Neuromuscular electrical muscle stimulation and lupin protein supplementation could significantly reduce the process of atrophy.Trial registrationClinicalTrials.gov, identifier NCT02698878
Highlights
After 58 days of wearing the orthosis the percentage loss of volume in the entire triceps surae muscle of the control subjects (-11.9 ± 4.4%, mean ± standard deviation) was reduced by the countermeasure (-3.5 ± 7.2%, p = 0.032)
Unloading of calf musculature by an orthotic device resulted in the expected loss of muscle volume and maximum of plantar flexion torque
Chronic unloading of skeletal muscles commonly results in muscle atrophy, which is more pronounced in muscles involved in locomotion than in muscles predominantly involved in joint stabilization [1]
Summary
Chronic unloading of skeletal muscles commonly results in muscle atrophy, which is more pronounced in muscles involved in locomotion than in muscles predominantly involved in joint stabilization [1]. Muscle atrophy is a negative side effect of immobilization by bed rest or by orthopaedic devices which are used to protect healing tissues. Astronauts represent a special group of healthy persons who are severely affected by atrophy of leg and back musculature because of microgravity-induced chronic unloading. Formerly used countermeasures have only been partially effective in preserving leg and back muscle volume and function [2,3,4,5], whereas in recent years astronauts who trained on the novel Advanced Resistive Exercise Device (ARED) returned back from space in a visibly better condition [6] (personal observations). The development of more efficient and safer for countermeasures conserving muscles and bones in space is still an ongoing challenge
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
