Inertia is the natural tendency of objects in motion to stay in motion and objects at rest to stay at rest, unless a force causes its speed or direction to change. It is one of the fundamental principles in classical physics, and described by Isaac Newton in his first law of motion. It is one of the primary manifestations of mass, one of the core quantitative properties of physical systems. Newton writes:
LAW I. Every object perseveres in its state of rest, or of uniform motion in a right line, except insofar as it is compelled to change that state by forces impressed thereon.
An accelerometer is a device that measures the proper acceleration of an object. Proper acceleration is the acceleration of the object relative to an observer who is in free fall. Proper acceleration is different from coordinate acceleration, which is acceleration with respect to a given coordinate system, which may or may not be accelerating. For example, an accelerometer at rest on the surface of the Earth will measure an acceleration due to Earth's gravity straight upwards of about g ≈ 9.81 m/s2. By contrast, an accelerometer that is in free fall will measure zero acceleration.
A dynamometer or "dyno" for short, is a device for simultaneously measuring the torque and rotational speed (RPM) of an engine, motor or other rotating prime mover so that its instantaneous power may be calculated, and usually displayed by the dynamometer itself as kW or bhp.
Muscle contraction is the activation of tension-generating sites within muscle cells. In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as when holding something heavy in the same position. The termination of muscle contraction is followed by muscle relaxation, which is a return of the muscle fibers to their low tension-generating state.
Strength training, also known as weight training or resistance training, involves the performance of physical exercises that are designed to improve strength and endurance. It is often associated with the lifting of weights. It can also incorporate a variety of training techniques such as bodyweight exercises, isometrics, and plyometrics.
A squat is a strength exercise in which the trainee lowers their hips from a standing position and then stands back up. During the descent, the hip and knee joints flex while the ankle joint dorsiflexes; conversely the hip and knee joints extend and the ankle joint plantarflexes when standing up. Squats also help the hip muscles.
An isometric exercise is an exercise involving the static contraction of a muscle without any visible movement in the angle of the joint. The term "isometric" combines the Greek words isos (equal) and -metria (measuring), meaning that in these exercises the length of the muscle and the angle of the joint do not change, though contraction strength may be varied. This is in contrast to isotonic contractions, in which the contraction strength does not change, though the muscle length and joint angle do.
Plyometrics, also known as jump training or plyos, are exercises in which muscles exert maximum force in short intervals of time, with the goal of increasing power (speed-strength). This training focuses on learning to move from a muscle extension to a contraction in a rapid or "explosive" manner, such as in specialized repeated jumping. Plyometrics are primarily used by athletes, especially martial artists, sprinters and high jumpers, to improve performance, and are used in the fitness field to a much lesser degree.
The good-morning is a weight training exercise. It is known as a good morning because of the movement in the erector spinae which resembles the bow that traditionally begins a schoolday in some East-Asian countries. The erector spinae muscles of the lower back work isometrically to keep the spine in an extended position while the hamstrings and gluteus maximus work isotonically to perform hip extension. Other muscles are involved in stabilizing weight on the back and maintaining balance.
A negative repetition is the repetition of a technique in weight lifting in which the lifter performs the eccentric phase of a lift. Instead of pressing the weight up slowly, in proper form, a spotter generally aids in the concentric, or lifting, portion of the repetition while the lifter slowly performs the eccentric phase for 3–6 seconds.
Weighted clothing are garments that have heavy materials incorporated into them, to add weight to various parts of the body, usually as part of resistance training. The effect is achieved through attaching weighted pieces to the body which leave the hands free to grasp objects. Unlike with held weights or machines, weighted clothing can leave users more able to do a variety of movements and manual labour. In some cases certain weighted clothing can be worn under normal clothing, to disguise its use to allow exercise in casual environments.
Backward running, also known as backwards running, running backwards, reverse running, retro running, or retro locomotion is the act of running in reverse, so that one travels in the direction one's back is facing rather than one's front. It is classed as a retro movement, the reverse of a normal movement.
In an isotonic contraction, tension remains the same, whilst the muscle's length changes. Isotonic contractions differ from isokinetic contractions in that in isokinetic contractions the muscle speed remains constant. While superficially identical, as the muscle's force changes via the length-tension relationship during a contraction, an isotonic contraction will keep force constant while velocity changes, but an isokinetic contraction will keep velocity constant while force changes. A near isotonic contraction is known as Auxotonic contraction.
The Muscle Atrophy Research and Exercise System (MARES), part of the Human Research Facility (HRF), was launched on 5 April 2010 (STS-131) in a stowed position inside the HRF MARES Rack, integrated into a Multi-Purpose Logistics Module (MPLM) and transported to the International Space Station. When deployed, MARES was attached to the seat tracks of an International Standard Payload Rack (ISPR) located in the Columbus Laboratory.
Eccentric training is a type of strength training that involves using the target muscles to control weight as it moves in a downward motion. This type of training can help build muscle, improve athletic performance, and reduce the risk of injury. An eccentric contraction is the motion of an active muscle while it is lengthening under load. Eccentric training is repetitively doing eccentric muscle contractions. For example, in a biceps curl the action of lowering the dumbbell back down from the lift is the eccentric phase of that exercise – as long as the dumbbell is lowered slowly rather than letting it drop.
Architectural gear ratio, also called anatomical gear ratio (AGR) is a feature of pennate muscle defined by the ratio between the longitudinal strain of the muscle and muscle fiber strain. It is sometimes also defined as the ratio between muscle-shortening velocity and fiber-shortening velocity.
Even before the very beginning of human space exploration, serious and reasonable concerns were expressed about exposure of humans to the microgravity of space due to the potential systemic effects on terrestrially-evolved life forms adapted to Earth gravity. Unloading of skeletal muscle, both on Earth via bed-rest experiments and during spaceflight, result in remodeling of muscle. As a result, decrements occur in skeletal muscle strength, fatigue resistance, motor performance, and connective tissue integrity. In addition, there are cardiopulmonary and vascular changes, including a significant decrease in red blood cell mass, that affect skeletal muscle function. This normal adaptive response to the microgravity environment may become a liability resulting in increased risk of an inability or decreased efficiency in crewmember performance of physically demanding tasks during extravehicular activity (EVA) or upon return to Earth.
Locomotion in space includes all actions or methods used to move one's body in microgravity conditions through the outer space environment. Locomotion in these conditions is different from locomotion in a gravitational field. There are many factors that contribute to these differences, and they are crucial when researching long-term survival of humans in space.
The Advanced Resistive Exercise Device (ARED) is an exercise device designed by NASA to allow for more intense workouts in zero gravity. The device was flown to the International Space Station during STS-126 and installed in 2009 to replace its inefficient predecessor, the Interim Resistance Exercise Device. The device uses a system of vacuum tubes and flywheel cables to simulate the process of free weight exercises, such as squats, deadlifts, and calf raises, workouts which more effectively prevent lower muscle atrophy, though it has the capability to workout any muscle group. The ARED device can accommodate all astronauts on the ISS.
Flywheel training is a type of strength training where the resistance required for muscle activation is generated by the inertia of a flywheel instead of gravity from weights as in traditional weight training.
