The Effect of a Four-Week Proprioceptive Neuromuscular Facilitation Stretching Program on Isokinetic Torque Production

Abstract

Flexibility is widely accepted as an important component of fitness, yet flexibility training can be detrimental to muscle performance particularly where a high number of stretch cycles are performed. The purpose of this study was to investigate whether chronic PNF stretch training could successfully improve the knee flexion range of motion without having a detrimental effect on the peak isokinetic torque of the quadriceps. The minimum knee angle in flexion and the peak isokinetic quadriceps torque was measured at 120 and 270 degrees per second. Subjects then participated in a four week quadriceps flexibility training program consisting of three cycles of PNF stretching performed three times a week. The range of motion was recorded before and after the first stretching session of each week. At the end of the four week period the peak isokinetic quadriceps torque and flexibility was again measured. The mean (standard error) improvement in the knee flexion range of motion over the whole programme was 9.2 (1.45) degrees, typical gains following a single stretching session were around three degrees. Post-hoc analysis showed that the pre training session range of motion was significantly improved in Week 4 compared to the pre training session range of motion in Weeks 1 and 2 (p<0.05). There was no change (p=0.9635) in the peak isokinetic torque produced at 120 degrees per second (Week 1: 121.9 (4.6) N.m; Week 2: 121.9 (5.2) N.m) or at 270 degrees per second (Week 1: 88.1 (3.4) N.m; Week 2: 88.6 (4.9) N.m). These findings suggest that it is possible to improve flexibility using three PNF stretch cycles performed three times a week without altering muscle isokinetic strength characteristics.

Positive Effects of Proprioceptive Neuromuscular Facilitation Stretching on Sports Performance: A Review

“…A 6 weeks (5 days a week x 30s) PNF stretching training also didn't cause a change on passive resistive torque (Konrad, Gad & Tilp 2015). Minshull et al (2014) also received similar results in his study in which similar protocols used (8 weeks, 3 days a week) Higgs and Winter (2009) could not find any evidence showing that PNF training (4 weeks, 3 times a week) is harmful to isokinetic torque generation. This study indicated that increasing flexibility does not have a negative effect on isokinetic torque.…”

“…Chronic effects were studied in all of these studies. There were positive effects in 5 studies (Nelson et al 1986, Worrell, Smith & Winegardner 1994, Handel et al 1997, Chen et al 2009, Chen et al 2011), null effect in 2 studies (Almeida et al 2009, Higgs & Winter 2009). There was null effect together with positive effect in 1 study (Kofotolis et al 2002), (Table 3).…”

Specificity in ROM Rehabilitation

“…[67][68][69] One study demonstrated that 4 weeks of contract-relax stretch training (proprioceptive neuromuscular facilitation) of the knee improved flexion range but did not alter the active movement performance (peak isokinetic quadriceps torque). 70 In another study, 10 weeks of lower limb stretching had no effect on vertical jumps. 71 Similarly, 6 weeks of passive static stretching and contract-relax stretching improved the ROM but neither had any significant effect on the drop jumps.…”

Efeito agudo do alongamento estático e facilitação neuromuscular propriocetiva sobre o desempenho do número de repetições máximas em uma sessão de treino de força

“…Os exercícios de alongamento são normalmente realizados como parte integrante da rotina de aquecimento com o objetivo de manter ou melhorar a flexibilidade, prevenir lesões, retardar dores musculares e se realizado de forma crónica promover melhoras sobre o desempenho físico (Higgs & Winter, 2009). Para Pereira, Brust e Barreto (2007), vários métodos de alongamento são utilizados clinicamente e no desporto, possuindo como principal característica a promoção e manutenção dos níveis de flexibilidade.…”