Editing Exercise (section)

=== Fitness ===
{{Main|Physical fitness}}
Most people can increase fitness by increasing [[physical activity]] levels.<ref name=":0">{{cite journal | vauthors = Neil-Sztramko SE, Caldwell H, Dobbins M | title = School-based physical activity programs for promoting physical activity and fitness in children and adolescents aged 6 to 18 | journal = The Cochrane Database of Systematic Reviews | volume = 2021 | issue = 9 | pages = CD007651 | date = September 2021 | pmid = 34555181 | pmc = 8459921 | doi = 10.1002/14651858.CD007651.pub3 }}</ref> Increases in muscle size from resistance training are primarily determined by diet and testosterone.<ref>{{cite journal | vauthors = Hubal MJ, Gordish-Dressman H, Thompson PD, Price TB, Hoffman EP, Angelopoulos TJ, Gordon PM, Moyna NM, Pescatello LS, Visich PS, Zoeller RF, Seip RL, Clarkson PM | display-authors = 3 | title = Variability in muscle size and strength gain after unilateral resistance training | journal = Medicine and Science in Sports and Exercise | volume = 37 | issue = 6 | pages = 964–972 | date = June 2005 | pmid = 15947721 }}</ref> This genetic variation in improvement from training is one of the key physiological differences between elite athletes and the larger population.<ref>{{cite journal | vauthors = Brutsaert TD, Parra EJ | title = What makes a champion? Explaining variation in human athletic performance | journal = Respiratory Physiology & Neurobiology | volume = 151 | issue = 2–3 | pages = 109–123 | date = April 2006 | pmid = 16448865 | doi = 10.1016/j.resp.2005.12.013 | s2cid = 13711090 }}{{cbignore|bot=medic}}</ref><ref name="newsci_geddes">{{cite magazine| vauthors = Geddes L | title = Superhuman| pages = 35–41| magazine = New Scientist| date = 28 July 2007}}</ref> There is evidence that exercising in [[middle age]] may lead to better physical ability later in life.<ref>{{cite news| url=http://www.medicineonline.com/news/12/10297/Being-active-combats-risk-of-functional-problems.html | title=Being active combats risk of functional problems}}</ref>

Early motor skills and development is also related to physical activity and performance later in life. Children who are more proficient with motor skills early on are more inclined to be physically active, and thus tend to perform well in sports and have better fitness levels. Early motor proficiency has a positive correlation to childhood physical activity and fitness levels, while less proficiency in motor skills results in a more sedentary lifestyle.<ref>{{cite journal | vauthors = Wrotniak BH, Epstein LH, Dorn JM, Jones KE, Kondilis VA | title = The relationship between motor proficiency and physical activity in children | journal = Pediatrics | volume = 118 | issue = 6 | pages = e1758–e1765 | date = December 2006 | pmid = 17142498 | doi = 10.1542/peds.2006-0742 | s2cid = 41653923 }}</ref>

The type and intensity of physical activity performed may have an effect on a person's fitness level. There is some weak evidence that [[high-intensity interval training]] may improve a person's [[VO2 max]] slightly more than lower intensity endurance training.<ref>{{cite journal | vauthors = Milanović Z, Sporiš G, Weston M | title = Effectiveness of High-Intensity Interval Training (HIT) and Continuous Endurance Training for VO2max Improvements: A Systematic Review and Meta-Analysis of Controlled Trials | journal = Sports Medicine | volume = 45 | issue = 10 | pages = 1469–1481 | date = October 2015 | pmid = 26243014 | doi = 10.1007/s40279-015-0365-0 | s2cid = 41092016 | url = https://research.tees.ac.uk/ws/files/6460688/561180.pdf }}</ref> However, unscientific fitness methods could lead to sports injuries.{{source needed|date=October 2024}}