Immediate and Long-Term Effectiveness of Proprioceptive Neuromuscular Facilitation and Static Stretching on Joint Range of Motion, Flexibility, and Electromyographic Activity of Knee Muscles in Older Adults

Introduction and Objective: Previously, various stretching techniques were compared to study their effects on the different physiological parameters of hamstring muscles in the elderly population. There is no research that compares the immediate and long-term effects of proprioceptive neuromuscular facilitation-contract-relax (PNF-CR) and static stretching (SS) techniques on knee range of motion (ROM), hamstring flexibility, and knee flexor muscle EMG activity in the elderly. This study intends to compare the same. Methods: A total of 30 males aged 55-75 years were randomly assigned into the PNF-CR group (n = 10), SS group (n = 10), and control group (n = 10). The PNF-CR group received four trials of the contract-relax technique, the SS group received passive stretching of an 80 s duration by the therapist, and the control group received no intervention. A total of 12 sessions were given during the four-week period. Knee range of motion, electromyographic activity of the biceps femoris, and the sit-and-reach test were taken for the dominant side thrice: pre-intervention, immediately after stretching, and after the training period. Results: A statistically significant difference was observed in the maximum voluntary isometric contraction (MVIC) of biceps femoris between the PNF and the control groups (p = 0.01) after four weeks of intervention. The knee ROM and hamstring flexibility for the PNF group showed significant improvement immediately post-test (p = 0.01) and after four weeks of training (p = 0.07 and p = 0.001). SS showed significant results for both ROM and flexibility after four weeks of intervention (p = 0.001), and significant immediate post-test improvements were seen for ROM only (p = 0.007). Conclusions: PNF stretching has an immediate, as well as long-term, effect on knee ROM and hamstring flexibility, whereas it has only a long-term effect on muscle electromyographic activity. SS has an immediate, as well as long-term, effect on knee ROM and only a long-term effect on hamstring flexibility, without any immediate or long-term effects on muscle electromyographic activity.