5 Amazing Things That Happen After Just a Month of Practicing Yoga

We live in an increasingly digital and unfocused world. Many of us feel overwhelmed by the torrent of information every day. Now, with almost everyone working at home, it's even easier to get distracted and fall into the internet rabbit hole.

Instead of checking Instagram or Facebook for the 10th time, maybe it would be a better idea to put your phone aside and practice some yoga? Yoga is a powerful way to calm your nervous system and energize yourself to greet the morning sun.

Staring at a screen has been shown to raise cortisol levels. Cortisol is a stress hormone released by our brain to help us act on instincts to cope with physical threats. Cortisol's release triggers physiological changes, such as spikes in blood pressure, blood sugar, and heart rate. In contrast, studies have shown that yoga can decrease cortisol's secretion and improve your overall health.

What about retraining your brain to focus again, rather than seeking constant stimulation? Many people are distracted and stressed out, making it harder to manage their lives. To find some quiet time for yourself in your often chaotic schedule, just try squeezing in 15 minutes of daily yoga practice!

Here are just a few of the most impressive benefits of yoga after only a month:

  1. Yoga helps you become more body aware and boost your mental health. Yoga is a great tool to improve your mental health without medication. Depression, sleep disorders, and other mental health conditions can all benefit from practicing yoga.
  2. You would notice a physical change. Stress and anxiety may leave your muscles and tissues tight, tired, and stuck. Yoga can help you build muscular strength and retrains your deep connective tissue.
  3. You may lose weight. Losing weight is not only about highly intensive exercises all the time. Stretching also can help you lose subcutaneous fat significantly.
  4. Yoga also helps reduce chronic pain. It's not a joke at all. I have a few friends that can't survive without practicing yoga. One of them has chronic pain in her lower back. She used to do physiotherapy every month; it did work. But with March lockdown, she couldn't continue. Constant chronic pain isn't something to mess around with. She decided to start practicing yoga, and she has found yoga to be a natural pain relief treatment! What a great reason to give it a try!
  5. If you want to become more creative, it may be time to roll out your mat. Deep breathing techniques can stimulate and increase your happy, calm brain waves and help you tap into a place of connection and creativity.

I would encourage everyone to introduce yoga into daily routines. It's one habit that may change you for the better.

To Shave or Not to Shave?

The norms are slowly changing. It's still quite rare to see a woman in public with facial hair and unshaved armpits. But recently, lots of anti-shaving movements have emerged that seem to be going mainstream. Women worldwide are asking themselves the same questions: "Why are we supposed to be perfectly hairless at all times. Why should we adhere to beauty standards imposed by social media to feel accepted"? Those movements are trying to encourage women to embrace their bodies and improve their self-worth.

Apart from anti-shaving movements, after quarantine, plenty of women have started shaving their faces! This "new-new skin-perfecting" technique, which is so-called "dermaplaning," has suddenly gained 'trending' status.

But what is dermaplaning?

Dermaplaning is the act of removing peach fuzz and dead skin cells from the face with a razor, leaving it softer and smoother. The question that immediately comes to mind is: does any woman nowadays really have time or even a subtle inclination to shave her entire face as men do? The answer is YES.

Let's do a little research on this subject. From a biological point of view, men and women are designed differently. The first evident distinction, among others, is the ability to grow a beard. In fact, men have more resilient skin with a higher density of collagen than women.

Secondly, shaving might exfoliate skin and apparently keep it soft, but if you're already using a facial cleansing brush or washcloth on your face, that's already severe scrubbing. Shaving may make your skin more sensitive and eventually cause skin damage, which might lead to skin aging. Moreover, face shaving can also cause ingrown hairs. So ladies, please, think twice before reaching for the razor!

And what about men? How common is it for them to shave bodies nowadays?

In reality, it's not as uncommon as you might think — the days when only women shaved their bodies have gone. Many men are prone to body shaving for various reasons, such as improving athletic performance and personal hygiene, avoiding unpleasant body odor, and, simply, because of aesthetic reasons. It is widespread for male body hair to be removed in the fitness world to improve performance and show off hard-earned muscles. Even though male body hair removal is nothing new, it's a well-known fact that even Ancient Egyptians, Greeks, and Romans were also passionate about man body shaving. These days young men are more inclined to undergo hair removal, including their back, neck, underarms, and sometimes even legs.

Anyway, it's totally up to you to shave or not to shave. Everyone has a right to make informed decisions and ask themselves why they do it.

Stay cool and healthy.

Does Electrical Myostimulation Reduce Your Recovery Time?

Whether you are an elite athlete, a casual workout fan,  or simply recovering from an injury, electrical Myostimulaton could be your secret weapon to a faster recovery time.

Previously, a sports injury or post-operative injury to the muscles required many months of intense physiotherapy. One tool that is frequently used in rehabilitation is ice equipment, to cool the injury and reduce swelling. Another is a piece of beauty equipment that also has physical therapy benefits – the myostimulation machine.

How Does Electrical Myostimulation Work?

Electrical myostimulation works by connecting the injured muscles to pads, which conduct electrical impulses through the damaged muscle. This increases blood flow, which, in turn, helps eliminate waste products from the area. It also works the muscle in the same way an exercise session would, by contracting and relaxing the muscle, in a similar way to how it would be used if lifting weights or strength training.

While some EMS machines are available for home use, a spa system in a beauty or aesthetic clinic is often a better option. Therapists are trained to know the optimal places to put the pads and can ensure that the right amount of current is passed through the muscle, to avoid exacerbating an industry further. A good therapist who offers EMS can create a customised treatment plan that increases the level of electrical current gradually over the course of treatment, to avoid the possibility of any further muscular damage.

Extra Pain Relief

Electrical myostimulation isn’t just for injured muscles that are causing problems. It is also ideal for use by athletes and fitness fans between workouts, to help reduce the recovery time between sessions.

Not only can an electrical myostimulation treatment help to restore the muscles toning and firming actions, but it can also work to relive pain and inflammation. It will help to minimise recovery time and get people back to their best faster than those who choose to recover without using EMS.

The Heart is a Muscle Too

There is some research that indicates that electrical myostimulation is a great way for those who are recovering from a heart attack to regain aerobic ability and oxygen uptake, compared to those who rehabilitate using regular aerobic activity. If you are recovering from heart problems, it is vital to consult a professional and use a credible medical aesthetics device for EMS in a spa or physiotherapist setting, before considering a home-use device without professional guidance.






Muscle Stimulation Technology

Muscle Stimulation Technology

Many a Space Shuttle astronaut has been aided in orbit by the extended reach of the six degree of freedom robot arm, termed by NASA as the Remote Manipulator System or RMS.

Control systems for an RMS simulator have been merged with software and high density hardware to run an electrical stimulation medical device. This fusion of aerospace research and biomedical need is the work of Electrologic of America, Inc., based in Dayton, Ohio.

Electrologic of America (ELA) manufactures several functional electrical stimulation (FES) medical devices. Neuromuscular electrical stimulation, a technique which is commonly referred to as FES, has been used to revitalize purposeful movement to muscles crippled by spinal cord injuries. FormerSuperman star Christopher Reeve, who suffered paralysis after falling from a horse, uses the StimMaster FES Ergometer. Using StimMaster, paraplegics and quadriplegics can get a full cardiovascular workout equivalent to jogging three miles three times per week.

Under a Goddard Space Flight Center contract, ELA was able to refine the process of densely packing circuitry on personal computer boards. ELA was able to provide significant contributions to Goddard adaptive, closed-loop control systems for the Remote Manipulator System Simulator (RMSS). This required design and fabrication of a new computer-controlled servo system for manipulation of the six-axis, 5,000-lb. mechanical arm which simulates the RMS carried on most Space Shuttle missions.

“With several modifications, we were able to use this type of technology to incorporate it into the software used in the StimMaster FES Ergometer,” explains Steven Petrofsky, ELA’s Executive Vice-President. He has been the recipient of several NASA awards for outstanding hardware design and robotic control developments, and was instrumental in the software development.

Joe Mica, the NASA RMSS systems engineer and manager, said that Petrofsky’s efforts were essential to the success of the RMSS. Ned Conklin of Forth Inc., an ELA subcontractor, implemented mission control software; Robert Lea of Ortech Engineering, Yashvant Jani of Hitachi and Mica together developed the RMSS fuzzy logic control design and published it in the CRC Press industry standard reference book The Industrial Electronics Handbook.

The StimMaster is used by persons with paralysis to pedal a recumbent bicycle by stimulating the leg muscles–hamstrings, quadriceps and gluteus maximi–to maintain a consistent rate of 50 revolutions per minute under resistance. Patients steadfastly using the StimMaster Ergometer have experienced diminished secondary symptoms related to paralysis.

“The results of the closed-loop, adaptive control under resistance is the reversal of atrophy, improved circulation and the relaxation of muscle spasms,” Petrofsky adds.

The StimMaster incorporates sensors, located within the ergometer, that provide continuous feedback to a computer. This computer controls the rate of pedaling through muscle stimulation, thereby achieving a rhythmical pedaling motion. Because the units are designed for home as well as clinical use, a person suffering from spinal cord injury can carry out a therapy program in the privacy of their own residence.

StimMaster’s advanced computer continually monitors the patient’s progress every 1/40th of a second and adjusts the settings to meet the patient’s needs.

ELA’s work for NASA on computer circuitry has also been applied to the VST-100. This portable, electrical stimulation equipment was developed by Petrofsky exclusively for V-Care Health Systems, Inc., based in Washougal, Washington.

The state-of-the-art VST-100 can increase bloodflow to afflicted areas, rejuvenate muscles and improve recovery time of an injured person–all through electrical stimulation. When used by a person distressed by carpal tunnel syndrome, as example, the VST-100 administers electrical pulses that increase circulation in the wrist, which opens up nerve pathways. Using the muscle stimulator technology, a person can return to the job more quickly, work productivity is increased, and health-care costs are decreased.

Article from : https://spinoff.nasa.gov/spinoff1997/hm1.html

Electrically Stimulated Antagonist Muscle

Electrically Stimulated Antagonist Muscle Contraction Increased Muscle Mass and Bone Mineral Density of One Astronaut – Initial Verification on the International Space Station


It is well known that atrophy of the musculoskeletal system due to disuse occurs among astronauts. For instance, atrophy of the muscles and bones of astronauts in weightlessness is evident [, ]. Sarcopenia is widely used as one of the terms to express weakness and atrophy of the muscles, although it initially referred to atrophy due to aging. However this initial Sarcopenia has been classified as primary Sarcopenia, and all the other muscle weakness and atrophy has been included in secondary Sarcopenia by the Report of the European Working Group on Sarcopenia in Older People 2010 []. Disuse muscle atrophy is classified as secondary Sarcopenia, and we often experience it as a result of reduction of activity such as in the case of a clinically bed ridden patient. Zero gravity has been included as a cause of disuse and categorized as secondary Sarcopenia in this 2010 categorization.

A decrease in muscle volume was reported by 4–16%, and in strength was reported by 9–11% after 5–17 day short-term Space Shuttle flights []. 16–28 weeks stays on the Station Mir resulted in changes of 12–20% in volume []. It was also reported that volume of the gastrocnemius and soleus muscles decreased by 10% and by 15% respectively, and concomitant peak plantar flexor power decreased by 32% in nine subjects after about 6 months on the International Space Station (ISS) [].

Astronauts usually exhibit a decrease in Bone Mineral Density (BMD) in the hip and lumbar spine by 1.0% to 1.5% per month [,,]. This finding highlights the accelerated rate of BMD loss during spaceflight, contrasting remarkably with the typical age related rate of bone loss of 0.5% to 1.0% per year in older individuals on Earth []. The risk of fractures is of particular concern upon re-exposure to mechanical loading, such as during the exploration of an unknown planet or return to Earth’s full gravity field. Moreover, cumulative skeletal deconditioning could increase the risk of premature osteoporosis and of fractures later in life.

Such deteriorations of the musculoskeletal system are one of the main issues for a long term stay in space, and several countermeasures have been developed and their effectiveness reported [,,]. Concerning these countermeasures, the evidence report of the Human Research Program of NASA described as follows []. A very simple exercise device which consisted of nylon cords rotating around a shaft within the cylinder was used on some Apollo missions. After the first manned mission to Skylab 2 (Skylab project was the first United States orbital space station), a commercial device, termed “Mini Gym,” modified extensively and designated “MK-I,” was available to transmit the force on the arms, trunk, and legs. Subsequently developed exercise devices provided loads by extension springs or bungee cords. In the early phase of the ISS program, the interim Resistive Exercise Device which was an elastomer-based resistive exercise hardware was used. A further developed version, called advanced Resistive Exercise Device (ARED) was delivered to ISS in 2010 and is in use now. ARED delivers adjustable loads of up to 600 pounds produced by vacuum canisters to enable a constant force and inertial flywheels to simulate the inertial loads that would be experienced using free weights at 1-G gravity. Thus, the development of countermeasures has advanced, ARED especially has provided good results. However, ARED occupies a large space and is difficult to use on a small spaceship which will be indispensable for missions to the moon, establishment of a lunar base, and interplanetary travel to Mars. Furthermore, there is only one ARED system in ISS, and thus the astronauts on the ISS can’t exercise at the same time. If the ARED breaks down, it is a severe problem.

We have developed a compact training device named “hybrid training system” (HTS) that is designed to maintain the musculoskeletal system of astronauts by using an electrically stimulated antagonist to resist the volitional contraction of agonist muscles (Fig 1) []. HTS, which utilizes electrically stimulated antagonist force as resistance to joint motion instead of gravity, causes electrically stimulated muscles to provide resistance to the motion of an antagonist muscle undergoing training. In other words, electrical stimulation is applied to the antagonist muscle during joint motion, the electrically stimulated antagonist muscle contracts eccentrically and its tension becomes a resistance to the agonist muscle. During HTS training, both flexion and extension muscles contract simultaneously, and longitudinal force load will be applied on the sandwiched bone by these contracting muscles. Multiple ground-based experiments [] and a parabolic flight verification [] have been encouraging as to the possibility of use by astronauts, but, thus far, evaluation in space has not been conducted.

In this experiment, as an initial verification on the ISS, HTS was used for one of an astronaut’s upper extremities (the non-dominant arm) for four weeks, and the resulting muscle strength, mass and BMD were compared to those of the non-HTS arm (the dominant arm) to examine its orbital operation capability and utility, as well as the preventive effect of HTS for musculoskeletal atrophy of an astronaut in weightlessness.

Materials and Methods

Ethics Statement

IRB of the Japanese Aerospace Exploration agency: JAXA and National Aeronautics and Space Administration: NASA approved the design of this study protocol. The subject was given oral and written explanations of the study involving the objective of the training method and its risks, and then signed consent forms for participation in this research. The subject was assured that he could discontinue if he wished. The individual of figure in this manuscript has given written informed consent (as outlined in PLOS consent form) to publish these case details.


One of the ISS crew members was a candidate as the subject. The subject was allowed to perform daily operation and usual activities on the ISS including daily exercise and other experiments.



The system was basically the same as those used in previous ground based experiments [], however it was designed and manufactured for use in the ISS under the criteria of NASA (Chiyoda Advance Solutions, CHIYODA CORPORATION, Yokohama, Japan). For example, the hardware of the ground model was changed so that harmful gas would not be generated in case of a fire, and the electromagnetic wave produced by the stimulator had no adverse effects on ISS. HTS consists of an electric stimulator, battery, electrodes, motion sensor, and a muscle supporter (Fig 2). The size and weight of the HTS device were 280 mm × 180 mm × 100 mm and 1650 g.

Stimulator A constant voltage stimulator was used to prevent heat generation caused by impedance increase from deterioration or insufficient setting of the electrodes, and the restriction of electric current was also set to prevent overstimulation during decreasing impedance. The subject can set the stimulation intensity, and has the ability to determine overload for himself. The output of electric current is isolated by a transformer, and the DC component does not apply output to the human body. The maximum current of stimulation applied to the subject does not exceed 20mA in flight. The battery was a Canon BP-930 (Canon Inc. Tokyo Japan), which was already present on the ISS for a video camera. This battery was available for use, and lasts for 15 HTS training sessions when fully charged.


Gel coated carbon electrodes (SEKISUI CHEMICAL CO.,LTD, Tokyo Japan) were attached over the motor points of the biceps and triceps muscles using a supporter. The supporter was designed so that the subject would be able to set the electrodes at the proper position easily for himself (GOLDWIN INC., Tokyo, Japan).

Motion sensor

Joint motion was detected by expansion and retraction of a wire connected to a rotary encoder (ME-20-P, MUOTH ENGINEERING INC., Tokyo, Japan). The resolution, maximal detection speed, and maximal acceleration of the wire-rotary encoder were 0.01 mm, 15 m / min, and 7.8 m / s2, respectively.

Training protocol

Put on and set HTS

The electrodes were embedded in the supporter and attached over the motor points of the triceps and biceps muscles for the non-dominant upper arm only. Stimulation intensity was set at the level predetermined in a ground based adjustment 4 months before launch, and fixed for the ISS experiment. It was determined as 80% of maximal comfortable stimulation intensity as per previous ground based studies []. A constant stimulation intensity was used during the entire 4 week training period, and it was 21.0V on the triceps and 15.5V on the biceps muscle respectively.

HTS training

HTS training took place toward the end of the flight, starting at less than return- 7weeks (Fig 3). Reciprocal elbow curls of both upper extremities, 2-seconds of flexion and 2-seconds of extension, were performed. One set of training consisted of 10 elbow curls, and 10 sets of 10 elbow curls with 1 minute rest intervals between sets were performed during a training session. 15 minutes 40 seconds were required for one session. 3 sessions were performed per week for 4 weeks, totaling in 12 sessions of training performed on the ISS.


Ground based evaluations

Ground based evaluations were performed using high quality evaluation devices. Pre-flight evaluations were done 1.5 ± 0.5 months before launch, and post-flight evaluations were done within 7days of return to earth (Fig 3).

Muscle performance

Biodex System4-PRO (Biodex Medical Systems, Shirley, New York, USA) was used to evaluate muscle performance at Johnson Space Center. Measurement of elbow extension and flexion force was performed with isokinetic measurement at 180 degrees/min. In the isokinetic measurement, Peak Torque (Nm), Total Work (Joule: amount of work accomplished for the entire set) and Average Power (Watts: Total Work divided by time) were evaluated. Three sets of measurements were performed for the evaluation, and the maximum value was used for evaluation.

Muscle volume by MRI

Muscle volume measurement by Magnetic Resonance Imaging (MRI) (SIEMENS MAGNETOM Verio 3T, Washington, D.C., USA) was performed at the Specialty Care Center, Victory Lakes of the University of Texas Medical Branch. A 5mm diameter spherical capsule of vitamin D medicine (Alfarol, CHUGAI PHARMACEUTICAL CO. LTD., Tokyo, Japan) which contained lipid was attached as a marker on the subject’s upper arms to confirm the scan level. A scale formed from an elastic arm support band (GOLDWIN INC., Tokyo, Japan) was made to identify a constant distance from the humeral medial condyle. The arms were scanned bilaterally using T1-weighted images (TR/TE = 500/18 msWeWe). Eleven axial slices of 10mm thickness were prescribed on a coronal scan including the marker and acquired perpendicular to the main axis of the humerus. 3 slices including the center slice with the marker were used to compare muscle volume. A scale was also used for a tape measurement of arm circumference during inflight evaluation.


Dual Energy X-ray Absorptiometry: DXA (Hologic QDR 4500 W DXA scanner, Hologic Inc., MA, USA) was performed at Johnson Space center to evaluate bone mineral density: BMD, lean (muscle) mass and fat mass. DXA data was provided by the NASA data sharing program.

Inflight evaluations

Numerical Rating Scale (NRS) was checked by the subject after the first three sessions of training to assess any pain experienced by the subject. Other inflight evaluations were performed using simple evaluation methods 6 days before and 5 days after the 4week training period (Fig 3).

Isometric peak force

Muscle force measurement was performed using a hand held dynamometer (HHD) (GT 310, OG Giken, Okayama, Japan) (Fig 4A). HHD was used to evaluate elbow extension and flexion strength. The subject held the HHD himself, and isometric elbow force was measured by HHD as the subject pressed it to the hand rail in an erect position with the subject’s elbow joint at 90 degrees flexion position and feet fixed in a foot rest. For the precise measurement, a wrist fixation supporter and body fixation harness were originally made and utilized. Measurement was performed three times, and the maximum value was used for evaluation.

Read more https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4546678/

Neuromuscular Electrical Stimulation

Neuromuscular Electrical Stimulation as a Potential Countermeasure for Skeletal Muscle Atrophy and Weakness During Human Spaceflight



Prolonged exposure to microgravity is associated with multi-system deconditioning including the cardiovascular () and musculoskeletal systems (). For instance, spaceflight-induced decrements in bone mineral density () and skeletal muscle mass () are common, particularly in lower-limb muscles (). Despite the considerable subject variability in the extent of muscle atrophy and functional loss, one of the most affected muscles seems to be the triceps surae, for which muscle fiber atrophy of 20% has been observed after 6 months of spaceflight (; ). Long-term spaceflight is also known to impair functionality (), neuromuscular control () and skeletal muscle strength (; ), with the strength decline primarily reflecting the loss of muscle mass (). Since the Skylab missions, it has been known that spaceflight induces more weakness in thigh than arm muscles, particularly the knee extensors, for which ∼20% of strength loss was reported after 1- and 2-month missions (). Recent studies suggest that in some individuals there are persistent neuromuscular control issues – compounded by and/or related to neurovestibular dysfunction (e.g., ) – resulting in extended periods of physical rehabilitation upon return to Earth (; ).

Besides muscle atrophy, spaceflight-related muscle weakness appears also to reflect a number of neuromuscular alterations, including a selective transformation of slow muscle fibers (type I) to faster phenotypes (type II) (). In fact, there is evidence that slow muscle fibers are predominantly affected by spaceflight (; ; ; ). Recent pilot data from the SARCOLAB study also suggest that reduced plantar flexor muscle volume may be associated with altered muscle architecture, contractile protein composition, and impaired muscle fiber contractility ().

Exercise Training as a Countermeasure

In order to address microgravity-induced deconditioning, exercise countermeasure training is performed daily on the International Space Station (ISS) (). Despite the medical standard agreements between the ISS international partners, each partner utilizes different training regimes that are to some extent individually tailored for each crewmember. For example, exercise countermeasures in the United States operating segment (NASA, ESA, JAXA, and CSA) consist of an integrated resistance and aerobic training schedule employing the advanced resistive exercise device (ARED), the second generation treadmill (T2), and a cycle ergometer with vibration isolation and stabilization (CEVIS) (). In contrast, the Russian operating segment employs the An external file that holds a picture, illustration, etc. Object name is fphys-10-01031-i001.jpg treadmill, the An external file that holds a picture, illustration, etc. Object name is fphys-10-01031-i002.jpg cycle ergometer, and the force loader (HC)-1 installed on the An external file that holds a picture, illustration, etc. Object name is fphys-10-01031-i002.jpg ergometer (). These tools are complemented by a set of resistance bands, compression thigh cuffs, lower body negative pressure trousers, suits for lower body compression and postural (axial) loading and also an electrical stimulator.

Despite the significant investment in both resources and crew time, astronauts typically require a period of rehabilitation upon return to Earth (; ), indicative that deconditioning is not entirely prevented (; ). In fact, there appears to be significant variability in the relative effectiveness of ISS countermeasures across various physiological systems (), but also between individuals (). The current countermeasure regimes appear unable to fully counteract muscle atrophy and weakness during long-duration ISS missions. For example, even high-volume aerobic training (∼500 km of running) complemented with high-intensity resistance training (∼5000 high-intensity heel raises) were insufficient to prevent plantar flexor weakness and atrophy during a 6-month ISS mission (). Furthermore, the current countermeasures require significant time and effort (both for exercise itself and for setup/stowage) in addition to potentially interfering with other crewmember tasks, including experimentation. This explains the increasing attention devoted to consider low-volume, simple and complementary exercise modalities, for use throughout, or potentially for only a short period prior to re-exposure to a gravitational vector, be it Earth, or the hypogravity of the Moon. One of those easily applicable and potentially powerful countermeasures – neuromuscular electrical stimulation (NMES) – is the focus of this article.

Rationale for NMES

Neuromuscular electrical stimulation involves delivering pre-programmed trains of stimuli to superficial muscles via self-adhesive skin electrodes connected to small portable current generators. Such electrical stimuli can be used to evoke relatively strong (albeit sub-maximal) muscle contractions, whose activation pattern is substantially different from that of voluntary contractions. NMES recruits motor units in a non-selective, spatially fixed, and temporally synchronous pattern (), with the advantage of activating fast muscle fibers at relatively low force levels, but produces greater muscle fatigue when compared with voluntary actions. If provided repeatedly, NMES improves muscle strength, power and endurance in healthy individuals (; ), even though these effects are not superior to those induced by voluntary training (). More importantly, NMES has been shown to preserve/restore muscle mass and aspects of neuromuscular function during/following a period of reduced activity due to illness, injury or surgery (; ; ; ), with greater effectiveness compared to other rehabilitation modalities (). As such, NMES is widely used as a rehabilitation strategy for patients with a range of diseases (; ), both during and following prolonged physical inactivity. NMES also provides beneficial effects in healthy subjects undergoing short periods of ground-based models of microgravity-induced deconditioning, e.g., bed rest or limb immobilization (). The majority of terrestrial NMES research has involved stimulation of knee extensor and/or plantar flexor muscles, whose atrophy and weakness can significantly impair locomotion. Although traditional countermeasures have the potential to partially attenuate spaceflight-induced muscle alterations (), no direct comparison of the effectiveness of these countermeasures versus NMES currently exists.

As such, this mini-review is focused on the use of NMES as a potentially-complementary countermeasure against skeletal muscle atrophy and weakness induced by human spaceflight. We provide an overview of the rationale and evidence for NMES-based terrestrial state-of-the-art knowledge, compare this to that employed in orbit and in ground-based analogs, and provide practical recommendations for possible NMES implementation in future space (or analog) missions.

NMES in Orbit: Sub-Optimal Use and Evidence

Roscosmos have employed different NMES devices (see top of Table 1) in orbit and in ground-based analogs (). The Tonus-3 unit () possesses four programs designed to stimulate: calf and quadriceps; calf and hamstring; calf, abdominal and back muscles; and shoulder muscles. Pulses have a duration of 1 ms and maximum current amplitude is ∼300 mA. Stimulation frequency is 10 kHz modulated at 60 Hz. Stimulation (ON) time is 0.5/1.5 s with a non-stimulation (OFF) period of 1.5 s, or alternatively an ON time of 10 ± 1 s with an OFF time of 50 ± 5 s. Another Russian stimulator, the Stimul-01 HF Set, generates high-frequency alternating sinusoidal electrical stimuli at 2.5 kHz with rectangular pulses modulated at 50 Hz. This device is intended for 40-min stimulation periods of lower limb, back, neck, shoulder and arm muscles, although few details have been published (). The Stimul-01 LF Set, a wearable NMES system, was uploaded to the ISS in 2006 () based on data suggesting that low-frequency stimulation is an effective countermeasure against the effects of ground-based (dry immersion) gravitational unloading (). The Stimul-01 LF Set provides NMES for 1 s followed by 2 s intervals. The symmetrical bipolar rectangular pulses have a duration of 1 ms and are delivered at 25 Hz, a stimulation pattern considered compatible with work-day activities without being unduly uncomfortable.

Read more : https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6700209/