G Fuel Energy & Endurance Tubs–Buy One Get One 20% Off

Twenty or 20 may refer to:

• 20 (number), the natural number following 19 and preceding 21
• one of the years 20 BC, AD 20, 1920, 2020

Buy may refer to a trade, i.e., an exchange of goods and services via bartering or a monetary purchase.

The term may not refer to:

Endurance (also related to sufferance, forbearance, resilience, constitution, fortitude, persistence, tenacity, steadfastness, perseverance, stamina, and hardiness) is the ability of an organism to exert itself and remain active for a long period of time, as well as its ability to resist, withstand, recover from and have immunity to trauma, wounds, or fatigue.

The term is often used in the context of aerobic or anaerobic exercise. The definition of "long" varies according to the type of exertion – minutes for high intensity anaerobic exercise, hours or days for low intensity aerobic exercise. Training for endurance can reduce endurance strength unless an individual also undertakes resistance training to counteract this effect.

When a person is able to accomplish or withstand more effort than previously, their endurance is increasing. To improve their endurance they may slowly increase the amount of repetitions or time spent; in some exercises, more repetitions taken rapidly improve muscle strength but have less effect on endurance. Increasing endurance has been proven to release endorphins resulting in a positive mind. The act of gaining endurance through physical activity decreases anxiety, depression, and stress, or any chronic disease. Although a greater endurance can assist the cardiovascular system this does not imply that endurance is guaranteed to improve any cardiovascular disease. "The major metabolic consequences of the adaptations of muscle to endurance exercise are a slower utilization of muscle glycogen and blood glucose, a greater reliance on fat oxidation, and less lactate production during exercise of a given intensity."

The term stamina is sometimes used synonymously and interchangeably with endurance. Endurance may also refer to an ability to persevere through a difficult situation, to "endure hardship".

In military settings, endurance is the ability of a force to sustain high levels of combat potential relative to its opponent over the duration of a campaign.

Energy (from Ancient Greek ἐνέργεια (enérgeia) 'activity') is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light. Energy is a conserved quantity—the law of conservation of energy states that energy can be converted in form, but not created or destroyed; matter and energy may also be converted to one another. The unit of measurement for energy in the International System of Units (SI) is the joule (J).

Forms of energy include the kinetic energy of a moving object, the potential energy stored by an object (for instance due to its position in a field), the elastic energy stored in a solid object, chemical energy associated with chemical reactions, the radiant energy carried by electromagnetic radiation, the internal energy contained within a thermodynamic system, and rest energy associated with an object's rest mass.

All living organisms constantly take in and release energy. The Earth's climate and ecosystems processes are driven primarily by radiant energy from the sun. The energy industry provides the energy required for human civilization to function, which it obtains from energy resources such as fossil fuels, nuclear fuel, renewable energy, and geothermal energy.

A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but has since also been applied to other sources of heat energy, such as nuclear energy (via nuclear fission and nuclear fusion).

The heat energy released by reactions of fuels can be converted into mechanical energy via a heat engine. Other times, the heat itself is valued for warmth, cooking, or industrial processes, as well as the illumination that accompanies combustion. Fuels are also used in the cells of organisms in a process known as cellular respiration, where organic molecules are oxidized to release usable energy. Hydrocarbons and related organic molecules are by far the most common source of fuel used by humans, but other substances, including radioactive metals, are also utilized.

Fuels are contrasted with other substances or devices storing potential energy, such as those that directly release electrical energy (such as batteries and capacitors) or mechanical energy (such as flywheels, springs, compressed air, or water in a reservoir).

G, or g, is the seventh letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages, and others worldwide. Its name in English is gee (pronounced ), plural gees.

The lowercase version can be written in two forms: the single-storey (sometimes "opentail") and the double-storey (sometimes "looptail") . The former is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children.