Stretching is popular among physiotherapists, athletic trainers and fitness instructors because it is believed to improve flexibility, injury prevention and promotion of healing. It may also play its role in decreasing delay-onset muscle soreness and improving movement economy. Many factors determine the stretching efficacy such as duration, age and number of repetitions. This essay will discuss the role of duration of stretch on hamstring muscle length in the normal adult population.
The hamstrings are a group of three muscles located on the posterior thigh (semimembranosus, semitendinosus and biceps femoris). The hamstrings cross two joints and act on the hip and the knee. Its predominant action is to flex the knee as well as an extension of the hip. The effectiveness of hamstrings stretches usually reported in the literature as an increase in the knee or hip joints Range of Motion (ROM).
The number of studies examined the efficacy of hamstrings stretches duration of up to 30 seconds found that 30 seconds stretch is more efficient for increasing muscle length than shorter time applications. Bandy and Irion (1994) established that 30 seconds stretch was superior to 15 seconds regardless of the number of repetitions. This result was in conjunction with the finding from a study conducted by Page (2012), demonstrated that 30 seconds duration is more effective than 15 seconds to elongate hamstrings and increase ROM of knee extension.
Furthermore, most authors who studied the effect of longer than 30-second duration stretch of hamstrings had found that no increase in flexibility occurred when the duration of stretching was increased from 30 to 60 seconds (Bandy, Irion and Briggler, 1997; Decoster et al., 2005). As for the more extended duration protocols when 30-second stretch was compared with 90 and 120 seconds, a similar result was also evident in Ford et al. (2005), demonstrating ineffectiveness of longer stretch.
In contrast, some studies have shown that stretching for a shorter duration with increased repetitions can result in similar ROM gains. The study conducted by Ayala and Andújar (2010) with 12×15, 6×30, 4×45 protocols were equally effective at increasing hamstring length. The other study by Cipriani et al. (2003) where 10-second duration stretch protocol in one leg was compared with 30-second protocol on the opposite leg of the same individual found no differences existed between two protocols. Authors concluded that ROM gains were equal, and regardless of the duration of a single stretch, the key to improvement was the total daily stretch time.
In conclusion, static stretching can be effective at increasing hamstrings length. Most of the evidence suggests that the flexibility of the hamstrings muscles for the 30-second duration of stretching may be the most effective practice. The practitioners need not perform static hamstrings stretch for more than 30 seconds when working with a normal adult population.
Ayala, F., & Sainz de Baranda Andújar, Pilar. (2010). Effect of 3 different active stretch durations on hip flexion range of motion. Journal of Strength and Conditioning Research, 24(2), 430-436. doi:10.1519/JSC.0b013e3181c0674f
Cipriani, D., Abel, B., & Pirrwitz, D. (2003). A comparison of two stretching protocols on hip range of motion: Implications for total daily stretch duration. The Journal of Strength and Conditioning Research, 17(2), 274. doi:10.1519/1533-4287(2003)017<0274:ACOTSP>2.0.CO;2
Decoster, L. C., Cleland, J., Altieri, C., & Russell, P. (2005). The effects of hamstring stretching on range of motion: A systematic literature review. The Journal of Orthopaedic and Sports Physical Therapy, 35(6), 377-387. doi:10.2519/jospt.2005.35.6.377
Ford, G. S., Mazzone, M. A., & Taylor, K. (2005). The effect of 4 different durations of static hamstring stretching on passive knee-extension range of motion. Journal of Sport Rehabilitation, 14(2), 95-107. doi:10.1123/jsr.14.2.95
Page, P. (2012). Current concepts in muscle stretching for exercise and rehabilitation. International Journal of Sports Physical Therapy, 7(1), 109-119. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/22319684
William D Bandy, & Jean M Irion. (1994). The effect of time on static stretch on the flexibility of the hamstring muscles. Physical Therapy, 74(9), 845-850. doi:10.1093/ptj/74.9.845
William D Bandy, Jean M Irion, & Michelle Briggler. (1997). The effect of time and frequency of static stretching on flexibility of the hamstring muscles. Physical Therapy, 77(10), 1090-1096. doi:10.1093/ptj/77.10.1090