Shana's (she/her) genotype has led her to have a relatively high proportion of slow-twitch muscle fibres. These muscle fibres typically support endurance activities, such as long-distance running. In school, Shana quickly takes to running and joins a club where she trains competitively. The fees are high, but Shana's parents find a way to make it work. After a severe injury one year, it was Shana's parents' support that helped her to get back on track in working towards her dream of competing at the Olympics. In this scenario, Shana's running abilities have been shaped by: