The PNF stretching method for each muscle was applied to the athlete in the form of self-stretching by the participant, with the direct treatment concept of hold and relax technique, with the training of a specialist physiotherapist. The muscle to be stretched (the antagonist muscle for the pattern - the muscle that causes the limitation) was first brought to the position where it could be extended, and at that point, the stretched muscle was contracted submaximally (65% of the intensity determined according to the Stretch Intensity Scale) for 5 seconds, causing isometric contraction. Then, the athlete was given 5 relax commands for the tense muscle. Then, the stretched muscle was stretched as far as it could go, and the muscle that needed to be stretched was passively stretched for 20 seconds (1 set). After a 5-second rest interval, the method was repeated and 8 sets (lasting 4 minutes) were performed for 1 muscle. Stretching was done on the hamstring muscle.

Classical static stretching was applied to the hamstring muscle in the same position for 30 seconds each, 8 repetitions, a total of 4 minutes for one leg and 8 minutes for both legs, in the stance position of PNF stretching.

PNF was applied to the hamstring muscle, with a 1-day washout period in between.

Normal resting tidal volume, chest width during maximum inspiration and maximum expiration were measured from the axillary region with a tape measure and recorded in centimeters.

Normal resting tidal volume, chest width during maximum inspiration and maximum expiration were measured from the xiphoid (epigastric) region with a tape measure and recorded in centimeters.

Normal resting tidal volume, chest width during maximum inspiration and maximum expiration were measured from the subcostal region with a tape measure and recorded in centimeters.

Hamstring muscle flexibility measurement. A digital goniometer was used.

Lumbar mobility was evaluated with the Schober Test. A tape measure was used in the testing procedure.