Before each on-court session, players performed
a standardized warm-up consisting of the 5'-5' test25 to
determine HR recovery. The test was performed on a
Plexi-cushion hard court in a 20-m shuttle-run fashion
at a constant intensity delivered by audio prompts. The
reminder of the warm-up consisted of 10 minutes of
dynamic footwork drills and 5 minutes of hitting. All
drill and match-play sessions were filmed by a digital
video camera (DSR-PDX10P, Sony, Japan) located 10
m above and 6 m behind each baseline.