Research Review by Dr. Shawn Thistle©



Study Title:

Impact of prior exercise on hamstring flexibility: A comparison of proprioceptive neuromuscular facilitation and static stretching


Funk DC, Swank AM, Mikla BM, Fagan TA, Farr BK

Publication Information:

Journal of Strength and Conditioning Research 2003; 17(3): 489-492.


Joint range of motion and flexibility are important physical attributes for the performance of athletic activities, as well as activities of daily living. Flexibility represents the ability to move a joint, or series of joints, through a full, unrestricted, pain-free range of motion. There are many individual factors that can determine flexibility including age, gender, amount of adipose tissue, skin tensile characteristics and so on.

This counterbalanced, within-subject (each subject served as their own control) study compared the effect of static stretching (SS), or proprioceptive neuromuscular facilitation stretching (PNF) with or without prior exercise on hamstring flexibility in college level athletes.

SS involves slow, controlled lengthening of a relaxed muscle (i.e. the way most people stretch), while PNF employs various combinations of alternating contractions and stretches (such as hold-relax, contract-relax etc.). Forty athletes (20 male, 20 female) from a variety of sports participated in the study.

Hip range of motion (ROM) and hence hamstring flexibility, was the main outcome measure. After baseline measurements, subjects either took part in a 60 minute cycling and upper body conditioning program, or no exercise; followed by either SS or PNF stretching. Within one week, the protocol was repeated, only with the stretching techniques switched. Each time hip ROM was re-measured. Results indicate that PNF stretching after exercise prompted the largest improvement in hamstring flexibility.

It should be noted that one reason for the lack of effect of SS in this study could be due to the advanced training state of the subjects. As collegiate level athletes, they may require more advance stretching methods (i.e. PNF) to achieve results.

Conclusions & Practical Application:

The results of this study will come as no surprise to those manual therapists and trainers that have used PNF stretches with patients or clients. The evidence is mounting that these techniques may be a superior way to improve joint range of motion and can easily be incorporated into many different programs.

Further, the fact that the PNF techniques were most effective AFTER exercise contributes to the growing body of evidence that flexibility work is best done after exercise.

Personally, I have seen best results using this approach and rely mainly on graded aerobic and dynamic motion warm-ups for my clients.