'Viscoelasticity' allows muscles to be elongated briefly after stretching

Exercise can lead to muscle microtears, but the body's repair systems cause those fibers to grow back larger.

Physiological muscle memory allows us to quickly regain lost musculature

The term "muscle memory" is most often associated with the neurological kind, which involves the development of strong and efficient neural pathways in the brain and spine. Physiological muscle memory also slows the loss of muscle mass, with both types affected by genetics and diet.

One of the leading theories behind muscle movement

According to the Sliding Filament Theory, skeletal muscle contraction is made possible by sarcomeres, which are made of bundles of myosin and actin proteins inside muscle cells. Myosin pulls itself along actin to contract a muscle, shortening the muscle and its cells and enabling physical movement. It then releases its grasp on actin so it can start the process over again if so commanded.

Myokines are molecules that facilitate some of the benefits of exercise

When muscles contract, they release ‘hope molecules’ (myokines) such as IL-6 and irisin. These proteins then travel through the bloodstream to reduce inflammation, improve insulin sensitivity, and even support brain repair. This piece illustrates how movement triggers a systemic healing cascade throughout the human body.

Exercise helps make your arteries more elastic.

How does muscle memory work?

Muscle memory is less about remembering how to ride a bike and more about what's happening in muscle cells. Increasing the cells' size, say by working out, leads to an increase in nuclei, which increases the production of mitochondria. When your fitness regimen falls to the wayside and you decide to re-enter the gym, these gains-based nuclei are already present to quicken muscle cells' adaptation to exercise.

Flexible integrated circuits can be built from carbon nanotubes and elastic materials

Stanford researchers arranged the nanotubes in fishnet-like networks that allow deformation without loss of function. The stretchable ICs have been shown to power micro-LED displays and may be used in smart clothing.

Complex molecular reactions in our tissues cause muscle contraction

When we want to move a muscle, a signal travels from the brain and into the muscle cells in question, sparking a chemical reaction that causes the muscle's smallest contractile units—sarcomeres—to shorten, forcing the muscle to contract.

Viscosity is a fluid's resistance to flow, which varies with temperature

Liquids become less viscous as temperature increases, while gases become more viscous and therefore flow more slowly. The increased gas collisions at higher temperatures contribute to greater friction between streamlines, increasing viscosity.

When experiencing turbulence, fluid elements undergo stretching and folding

Simulations show patches of fluid particles, such as splashes of milk, bend under turbulent flow, creating curvature that grows linearly then exponentially. This accelerated deformation enhances folding and mixing faster than other methods, such as stirring or beating.

How endurance athletes can build resilience

Long-distance runners and other endurance athletes can improve their performances using tips explored in this article. Findings from two recent studies show that strength training, high-altitude training, and intense interval sessions are all potential methods for ameliorating long-term athletic capabilities.

Muscles fatigue due to the loss of energy like ATP and glycogen

Adenosine triphosphate fuels muscle contraction, and with each contraction (like during exercise), the amount of ATP reduces. ATP helps potassium and sodium move across muscle membranes, generating ions and helping to contract the muscle.

How skeletal and smooth muscles differ

Skeletal and smooth muscles are two of the three muscle types found throughout the body. The former is attached to bones via tendons, enables limb movement, and is consciously controlled. The latter is found lining blood vessels and hollow organs (e.g., the intestines, stomach, and esophagus) and is managed by the autonomic nervous system, which means it's outside conscious control.

Winter Olympic sports highlight various laws and principles of physics

Figure skaters leverage the conservation of angular momentum during spins by tightening their bodies, and the skintight suits used in ski jumping help reduce drag. Centripetal force allows speedskaters to make tight turns, while friction on skis helps ski mountaineers climb slopes. No action can violate the conservation of energy.

Endurance art strains and exhausts the body

Artists like Marina Abramović are known for testing the limits of human endurance. Endurance art can involve carrying heavy objects or posing uncomfortably for long durations. (This resource contains some artistic depictions of violence.)

Running a ribbon around the edge of a blade creates curls because it stretches its outer side beyond the yield—the limit at which a material can be deformed but still return to its original shape once the force is removed.

Eating competitions can ruin a stomach's elasticity

Competitive eaters make room for all that food by toying with the stomach's ability to expand and contract. Still, doctors warn that repeated stress can destroy that ability, leading to further issues.

Developing adaptable brain-body systems lets athletes thrive beyond 30

Success in high-level sports after age 30 relies on physical fitness and building brain resilience through deliberate training, recovery, and stress regulation. This creates a feedback loop where body and mind reinforce each other.

Collagen supplements have become a multibillion-dollar industry

Beginning in our 20s, the amount of this protein in our skin, muscles, and connective tissue declines. But independent, high-quality studies—like those that are double-blind—have not yet shown a significant association between their use and evidence of it improving skin elasticity, reducing wrinkles, or combating hair loss. Some collagen supplements do seem to help with joint pain and knee function, but NPR cautions that studies on that purpose are industry-funded.

A breakdown of gelling agents used to modify a liquid's texture

Gelatin, agar, and other substances form a structural network that traps liquid, making it appear solid and enabling chefs to create stable layers in pastries and confectionery products. In different concentrations, they can also be used to thicken liquids into gels or encase them in gelatinous spheres.

The longest word in English is 189,819 letters long

The wildly-winding word (so long that we can't fit it here) is the proper name for titin, a protein that keeps muscles elastic.

Muscular system explained

Skeletal, cardiac, and smooth muscles form the system that powers movement, survival, and daily life. Skeletal muscles are voluntary, enabling conscious actions like lifting or walking, while cardiac and smooth muscles are involuntary, controlled by the autonomic nervous system. From every heartbeat to each breath, these three muscle types work in harmony to keep you moving, thriving, and alive.

Adhesion molecules and intercellular junctions allow cells to connect together

While some organic structures are mostly composed of non-cellular components (e.g., collagen and calcium phosphate minerals in bones), tissues and organs composed of connected cells rely on specialized proteins and connections to create watertight seals that protect cells within the interior from environmental molecules.

What is the muscular system?

The muscular system comprises three distinct types of muscle: smooth, cardiac, and skeletal. Cardiac muscles make up the heart, whereas smooth and skeletal muscles are found throughout the body. Smooth muscles line blood vessels and most organs, and skeletal muscles are responsible for moving the body or holding it stationary. All muscles are made of muscle cells or fibers, which give them the ability to contract.

Too little stress can also harm our health because mild or moderate stress—followed by recovery—helps make us resilient.

The universe expands by stretching space itself, not into anything beyond it

Thanks to Einstein’s relativity and Hubble’s observations, scientists understand that space stretches, like rising bread dough between raisins, with no "outside" to expand into. Some theories suggest our universe might be just one "bubble" in a vast multiverse, possibly floating on a higher-dimensional surface called a brane.

Tennis balls get their bounce from pressurized nitrogen inside vulcanized rubber, made from heating natural rubber with sulfur to create molecular links that harden the material.

Conditioners can help unshrink garments by lubricating fibers

Textile fibers relax and shrink due to heat and moisture, disrupting hydrogen bonds. While loosely knitted fabrics are more prone to shrinkage than tightly woven ones, synthetic fibres like polyester resist shrinkage due to their crystalline structure.

How muscles get their names

There are more than 600 muscles that crisscross the human body, and each has a name that's more than a simple label. Muscle names also typically communicate the muscle's size, behavior, length, location, appearance, direction, and attachments to bone. These names usually have Greek or Latin roots, such as in the case of the deltoid muscles, which are named in reference to the Greek letter delta (𐤃).

Spiders can make up to seven types of silk, with some able to withstand twice the force of ultra-high-strength steel of the same mass and length before breaking.

Why yoga teachers are dissecting cadavers

Thousands of fitness professionals are choosing to attend cadaver workshops to improve their understanding of anatomy and their teaching abilities. Though 3D virtual models give students a fresh way to explore the human body, medical students say experiencing the intricacies in person is far more instructive. As fitness professionals increase their understanding of the muscular and skeletal systems, their movement cues and instructions evolve in tandem.

Tardigrades’ intrinsically disordered proteins may help preserve biological matter

Researchers have attempted to create more drought-resistant crops by introducing proteins that help protect tardigrades in their dehydrated tun state. The proteins’ ability to stabilize molecular degradation may allow scientists to develop refrigeration-free storage for vaccines, insulin, and blood.

Strength training appears to make for a healthier, youthful-looking brain.

A Venus flytrap's hairs convert sensory touch into electrical signals

A stretch-activated ion channel called DmMSL10 acts as an amplifier, converting grazing contact into a strong impulse that the plant uses to react and close its jaw. To distinguish prey from raindrops or other stimuli, the jaw only closes when the hairs are touched twice in quick succession.

Synaptic plasticity allows neurons to communicate effectively and form memories

First proposed in 1949, synaptic plasticity allows the brain to adjust communication strength between neurons. This ability to change synaptic strength—either briefly or over long periods—is essential for learning and memory, with long-term synaptic plasticity forming the basis of how memories are stored.

Explore 1,800+ exercises with an interactive muscle map that lets you click any muscle to see targeted exercises, including video tutorials and written instructions.

Explore a visualization of curved spacetime under general relativity

While depictions involving bends in elastic fabrics are common to illustrate gravity, they are circular representations that rely on gravity in the real world to depict gravity in the model. The river model instead shows how bends in spacetime convert speed through time into speed through space, producing acceleration.

Some marine life can survive the extreme pressure of the deep ocean because of specialized molecules that strengthen proteins, enzymes, and cellular membranes.

Stretching and breathing are just two aspects of yoga

Most contemporary yoga studios focus on two of astanga yoga’s eight branches, as codified in the ancient text “Yoga Sutras of Patañjali”: asanas (physical postures) and pranayama (breath control). However, the larger practice of yoga includes six additional limbs: yama (universal ethics), niyama (individual ethics), pratyahara (control of senses), dharana (concentration), dhyana (meditation), and samadhi (pure consciousness).

Protein content and multiple fermentations create beer foam stability

Single-fermentation beers rely on protein viscosity for foam, with lipid transfer proteins transforming into stabilizing structures during fermentation. Scientists believe foam research may result in safer lubricants for electric vehicles.

Astronauts exercise on the International Space Station

Astronauts maintain bone, muscle, and cardiovascular health with physical activity. It's crucial that they make time to exercise for approximately two hours per day. This resource offers a behind-the-scenes look at how high-intensity workouts help prevent muscle atrophy, bone density loss, and aerobic decline during monthslong space missions.

Some research suggests that the gut microbiome influences our risk of heatstroke, with elevated exercise levels raising body temperature to unsafe levels and increasing gut permeability—causing a "leaky" gut.

Stress-induced adrenaline can trigger a 'hysterical strength' response

The stress response is a powerful ancient mechanism designed to maximize human survival—it can even result in superhuman strength. The adrenal glands are located just above the kidneys, and stress-induced adrenaline release causes more blood (and therefore more oxygen) to flow to your muscles, increasing performance.

Your feet can expand—permanently—due to pregnancy.

Nitinol is an example of a shape memory alloy, which can be trained to 'remember' a specific shape and, if deformed, revert to it upon being heated.

Using fitness wearables to track muscle wasting in astronauts

All that exercising, and astronauts still are likely to lose a large amount of muscle mass while in microgravity. Astronauts can lose up to 20 percent of their muscle in as little as five days in space. Currently, tracking muscle loss means waiting until astronauts land to remeasure their muscle density post-trip. This article explains a NASA-backed fitness wearable that may be able to track muscle atrophy as it happens.

Optimal human functioning requires movement

There is now ample evidence to back the centuries-old hypothesis that exercise is critical to human health. This review article explores the latest discoveries in exercise science, including how exercise is intrinsic to maintaining our organ systems throughout life.

Strengthening your butt muscles can help protect against running injuries

More than 28 million people may go running in the US every week, yet people often get hurt—especially with knee injuries—and this podcast explores the science on what happens to our bodies when we run and the effects on our muscles and joints. It also discusses safety tips, including the need to only add more distance to your runs in tiny increments, and that strengthening glute muscles via single-leg glute bridges may be particularly protective against injuries.

How trauma gets ‘under the skin’

A study examining the muscle function of older adults who have at least one adverse childhood experience (ACE) suggests that trauma digs itself into muscle cells. Participants who reported childhood trauma were found to have lower maximum levels of cellular energy than people who reported fewer or no ACEs. Such compromised mitochondrial function "doesn't bode well," as it relates to a variety of health and age-related outcomes.

Wrestlers maintain the illusion of a fictional narrative through 'kayfabe'

Outsiders are often confused by wrestling fans’ emotional investment in predetermined matches. After all, how can you be invested in a scripted sport? That question misses a key component of fans' love for pro wrestling. They suspend their disbelief in the same way that readers of novels do.