Saturday, August 11, 2007

Stretching 1 - not before exercise.

I want to write something about stretching. People like to stretch. It feels good. There is also an assumption that it is good. If you look around a gym - where most people have no idea what they are doing - you see folks stretching as if it is expected. It is the same when people start a running programme they stretch with great seriousness.....

It is assumed that it is good. But is it?

It is interesting if you look at the research. Research all seems to indicate that stretching before exercise is something that you should avoid.

Effects of differing intensities of static stretching on jump performance

Acute bouts of static stretching have been shown to impair performance. Most published studies have incorporated static stretching that stressed the muscle(s) to the point of discomfort (POD). There are very few studies that have examined the effects of submaximal intensity (less than POD) static stretching on subsequent performance. Ten participants were pre-tested by performing two repetitions of three different stretches to assess range of motion (ROM) and two repetitions each of five different types of jumps. Following pre-testing, participants were stretched four times for 30 s each with 30 s recovery for the quadriceps, hamstrings and plantar flexors at 100% (POD), 75% and 50% of POD or a control condition. Five minutes following the stretch or control conditions, they were tested post-stretch with the same stretches and jumps as the pre-test. All three stretching intensities adversely affected jump heights. With data collapsed over stretching intensities, there were significant decreases in jump height of 4.6% (P = 0.01), 5.7% (P < 0.0001), 5.4% (P = 0.002), 3.8% (P = 0.009) and 3.6% (P = 0.008) for the drop jump, squat jump, countermovement jump (CMJ) to a knee flexion of 70 degrees , CMJ using a preferred jump strategy and short amplitude CMJ respectively. An acute bout of maximal or submaximal intensity stretching can impair a variety of jumping styles and based on previous research, it is hypothesized that changes in muscle compliance may play a role.

Effects of Six Warm-Up Protocols on Sprint and Jump Performance
Rheba E. Vetter

Health, Physical Education, Recreation, and Dance Department, Northwest Missouri State University, Maryville, Missouri 64468


Vetter, R.E. Effects of six warm-up protocols on sprint and jump performance. J. Strength Cond. Res. 21(3):819– 823. 2007.—The purpose of this study was to compare the effects of 6 warm-up protocols, with and without stretches, on 2 different power maneuvers: a 30-m sprint run and a vertical countermovement jump (CJ). The 6 protocols were: (a) walk plus run (WR); (b) WR plus exercises including small jumps (EJ); (c) WR plus dynamic active stretch plus exercises with small jumps (DAEJ); (d) WR plus dynamic active stretch (DA); (e) WR plus static stretch plus exercises with small jumps (SSEJ); and (f) WR plus static stretch (SS). Twenty-six college-age men (n = 14) and women (n = 12) performed each of 6 randomly ordered exercise routines prior to randomly ordered sprint and vertical jump field tests; each routine and subsequent tests were performed on separate days. A 2 × 6 repeated measures analysis of variance revealed a significant overall linear trend (p 0.05) with a general tendency toward reduction in jump height when examined in the following analysis entry order: WR, EJ, DAEJ, DA, SSEJ, and SS. The post hoc analysis pairwise comparisons showed the WR protocol produced higher jumps than did SS (p = 0.003 0.05), and DAEJ produced higher jumps than did SS (p = 0.009 0.05). There were no significant differences among the 6 protocols on sprint run performance (p 0.05). No significant interaction occurred between gender and protocol. There were significant differences between men and women on CJ and sprint trials; as expected, in general men ran faster and jumped higher than the women did. The data indicate that a warm-up including static stretching may negatively impact jump performance, but not sprint time.


The Effect of Static, Ballistic, and Proprioceptive Neuromuscular Facilitation Stretching on Vertical Jump Performance
Paul S. Bradley, Peter D. Olsen, and Matthew D. Portas

Sport and Exercise Group, University of Teesside, UK


Bradley, P.S., P.D. Olsen, and M.D. Portas. The effect of static, ballistic, and proprioceptive neuromuscular facilitation stretching on vertical jump performance. J. Strength Cond. Res. 21(1):223–226. 2007.—The purpose of this study was to compare the acute effects of different modes of stretching on vertical jump performance. Eighteen male university students (age, 24.3 ± 3.2 years; height, 181.5 ± 11.4 cm; body mass, 78.1 ± 6.4 kg; mean ± SD) completed 4 different conditions in a randomized order, on different days, interspersed by a minimum of 72 hours of rest. Each session consisted of a standard 5-minute cycle warm-up, accompanied by one of the subsequent conditions: (a) control, (b) 10-minute static stretching, (c) 10-minute ballistic stretching, or (d) 10-minute proprioceptive neuromuscular facilitation (PNF) stretching. The subjects performed 3 trials of static and countermovement jumps prior to stretching and poststretching at 5, 15, 30, 45, and 60 minutes. Vertical jump height decreased after static and PNF stretching (4.0% and 5.1%, p < 0.05) and there was a smaller decrease after ballistic stretching (2.7%, p > 0.05). However, jumping performance had fully recovered 15 minutes after all stretching conditions. In conclusion, vertical jump performance is diminished for 15 minutes if performed after static or PNF stretching, whereas ballistic stretching has little effect on jumping performance. Consequently, PNF or static stretching should not be performed immediately prior to an explosive athletic movement.

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