• Selection bias

In Javaloyes\_2019, Kiviniemi\_2007, and Kiviniemi\_2010, neither the random component in the sequence generation nor the allocation concealment were described; therefore, the risk-of-bias selection was considered unclear. In Nuuttila\_2017, Schmitt\_2018, and Vesterinen\_2016, the risk of bias was considered high because the randomization sequence was, in the first stage, based on the results of certain physical condition tests, sport discipline, age, or gender. Furthermore, in the second stage, the random component or the allocation concealment was not described.
