Table 1. Relevance of the volume of coach-led practice in an athlete’s main sport and in other sports for the differentiation between senior international and national-level success (adapted and updated from [11]).

		Amount of main-sport practice		Amount of other-sports practice
No	Source	Childhood and adolescence	Adulthood	Childhood and adolescence	Adulthood
1	[12]	–	n.a.	+	n.a.
2	[13]	+/o	n.a.	n.a.	n.a.
3	[14]	o	n.a.	+/o	n.a.
4	[15]	o/–	o	o	o
5	[16]	o/–	o	+	+
6	[17]	o	o//–	o/+	o//+
7	[18]	–	o/n.a.	+	o/n.a.
8	[19]	o	o	+	n.a./o
9	[20]	o//–	o	o//+	o

Note: n.a.: no information available

Relevance for success:

+: sig. positive correlation (athletes achieving international senior-level success practiced more compared to ‘only’ nationally successful athletes)

–: sig. negative correlation (internationally successful athletes practiced less compared to ‘only’ nationally successful athletes)

o: no correlation between success and amount of practice

x/y: the majority of the results in this category correspond to x, but y was also found

x//y: x and y were found the same number of times

Note that study 2 [13] compared more successful Greek with less successful Canadian gymnasts.