Indoor rower
An indoor rower, or rowing machine, is a machine used to simulate the action of watercraft rowing for the purpose of exercise or training for rowing. Modern indoor rowers are often known as ergometers (colloquially erg or ergo) because they measure work performed by the rower (which can be measured in ergs). Indoor rowing has become established as a sport, drawing a competitive environment from around the world. The term "indoor rower" also refers to a participant in this sport. History. Chabrias, an Athenian admiral of the 4th century BC, introduced the first rowing machines as supplemental military  training devices. "To train inexperienced oarsmen, Chabrias built wooden rowing frames onshore where beginners could learn technique and timing before they went on board ship." Early rowing machines are known to have existed from the mid-1800s, a US patent being issued to W.B. Curtis in 1872 for a particular hydraulic-based damper design. Machines using linear pneumatic resistance were common around 1900—one of the most popular was the Narragansett hydraulic rower, manufactured in Rhode Island from around 1900–1960. In the 1970s, the Gjessing-Nilson ergometer from Norway used a friction brake mechanism with industrial strapping applied over the broad  rim of the flywheel. Weights hanging from the strap ensured that an adjustable and predictable friction could be calculated. The first air resistance ergometers were introduced around 1980 by Repco.In 1981, Peter and Richard Dreissigacker, and Jonathan Williams, filed for U.S. patent protection, as joint inventors of a "Stationary Rowing Unit". The first commercial embodiment of the Concept2 "rowing ergometer" was the Model A, a fixed-frame sliding-seat design using a bicycle wheel with fins attached for air resistance. The Model B, introduced in 1986, introduced a solid cast flywheel and the first digital performance monitor, which proved  revolutionary. This machine's capability of accurate calibration combined with easy transportability spawned the sport of competitive indoor rowing, and revolutionised training and selection procedures for watercraft rowing. Later models were the C (1993) and D (2003). In 1995, Casper Rekers, a Dutch engineer, was granted a U.S. patent for a (US 5382210A) "Dynamically Balanced Rowing Simulator". This device differed from the prior art in that the flywheel and footrests are fixed to a carriage, the carriage being free to slide fore and aft on a rail or rails integral to the frame. The seat is also free to slide  fore and aft on a rail or rails integral to the frame. Equipment. Motion type. Modern indoor rowers have their resistance provided by a flywheel. Indoor rowers that utilise flywheel resistance can be categorised into two motion types. In both types, the rowing movement of the user causes the footrests and the seat to move further and closer apart in co-ordination with the user's stroke. The difference between the two types is in the movement, or absence of movement, of the footrests relative to ground. The first type is characterised by the Dreissigacker/Williams device. With this type  the flywheel and footrests are fixed to a stationary frame, and the seat is free to slide fore and aft on a rail or rails integral to the stationary frame. Therefore, during use, the seat moves relative to the footrests and also relative to ground, while the flywheel and footrests remain stationary relative to ground. The second type is characterised by the Rekers device. With this type, both the seat and the footrests are free to slide fore and aft on a rail or rails integral to a stationary frame. Therefore, during use, the seat and the footrests move relative  to each other, and both also move relative to ground. Damper type. Piston resistance comes from hydraulic cylinders that are attached to the handles of the rowing machine. Braked flywheel resistance models comprise magnetic, air, and water resistance rowers. Magnetic resistance models control resistance by means of permanent magnets or electromagnets. Air resistance models use vanes on the flywheel to provide the flywheel braking needed to generate resistance. Water resistance models consist of a paddle revolving in an enclosed tank of water. Slides. Sometimes, slides are placed underneath the machine, which allows the machine to move back and forth smoothly  as if there were water beneath the rower. The slides can be connected in rows or columns so that rowers are forced to move together on the ergometer, similarly to the way they would match up their rhythm in a boat. Indoor rowers usually also display estimates of rowing boat speed and energy used by the athlete. Use. Exercise. Rowing is an efficient method of exercise which uses 86% of muscles when done with correct form. Indoor rowing primarily works the cardiovascular systems with typical workouts consisting of steady pieces of 20–40 minutes. The standard measurement of speed on an  ergometer is generally known as the "split", or the amount of time in minutes and seconds required to travel at the current pace. Other standard measurements units on the indoor rowing machine include calories and watts. Testing. Although ergometer tests are used by rowing coaches to evaluate rowers and are part of athlete selection for many senior and junior national rowing teams, data suggests that: "physiological and performance tests performed on a rowing ergometer are not good indicators of on water performance". Some standard indoor rower ergometer tests include: 250-m ergometer test, 2000-m ergometer test, 5km ergometer  test, 16000-m ergometer test and the 30 minute ergometer test. Technique. Rowing on an ergometer requires four basic phases to complete one stroke; the catch, the drive, the finish and the recovery. The catch is the initial part of the stroke. The drive is where the power from the rower is generated while the finish is the final part of the stroke. Then, the recovery is the initial phase to begin taking a new stroke. The phases repeat until a time duration or a distance is completed. At each stage of the stroke the back should remain in a  neutral, flat position, pivoting at the hips to avoid injury. Catch. Knees are bent with the shins in a vertical position. The back should be roughly parallel to the thigh without hyperflexion (leaning forward too far). The arms and shoulders should be extended forward and relaxed. The arms should be level. Drive. The drive is initiated by a push and extension of the legs; the body remains in the catch posture at this point of the drive. As the legs continue to full extension, the hip angle opens and the rower engages the core to begin the motion of the  body levering backward, adding to the work of the legs. When the legs are fully extended, the rower begins to pull the handle toward the chest with their arms, completings the stroke with the handle half way up the body and the forearms parallel to the ground. Finish (or release). The legs are at full extension and flat. The shoulders are slightly behind the pelvis, and the arms are in full contraction with the elbows bent and hands against the chest below the nipples. The back of the rower is still maintained in an upright posture and wrists should be  flat. Recovery. The recovery is a slow slide back to the initial part of the stroke, it gives the rower time to recover from the previous stroke. During the recovery the actions are in reverse order of the drive. The recovery is initiated by the extensions of the arms until fully extended in front of the body. The torso is then engaged by pivoting at the hips to move the torso in front of the hips. Weight transfers from the back of the seat to the front of the seat at this time. When the hands come over the knees , the legs are bent at the knees, moving the slide towards the front of the machine. As the back becomes more parallel to the thighs, the recovery is completed when the shins are perpendicular to the ground. At this point the recovery transitions to the catch for the next stroke. Sport. The first indoor rowing competition was held in Cambridge, Massachusetts in February 1982 with participation of 96 on-water rowers who called themselves the "Charles River Association of Sculling Has-Beens", hence the acronym, "CRASH-B". The core events for indoor rowing competitions that are currently competed in at  the World Rowing Indoor Championships are the individual 500m, individual 2000m, individual 1 hour and 3 minute teams event. Events at other indoor rowing competitions include the mile and the 2500 meter. Most competitions are organised into categories based on sex, age, and weight class.