Effect of participants’ static stretching knowledge or deception on the responses to prolonged stretching

Abstract

Much of the static stretching (SS) literature reports performance impairments with prolonged SS. However, it has been acknowledged that a limitation of these studies is participants' knowledge or bias. Since many participants have knowledge of the literature, their performance may be subconsciously influenced by expectations. Hence, the objective of this study was to examine the effect of stretching knowledge or deception on subsequent force output following SS. Two groups of male participants who were either aware (BIASED: 14) or unaware (DECEPTION: 14) of the SS literature participated. Unaware participants were misinformed that SS increases force production. Testing involved maximal voluntary isometric contractions (MVC) of the quadriceps and hamstrings at pre-, post-, and 5 min post-intervention (three 30-s passive hamstring stretches to the point of discomfort with 30-s rest intervals) or control. While the DECEPTION group displayed impaired knee flexion force (p = 0.04; 3.6% and 10.4%) following hamstrings SS, there was no significant impairment with the BIASED (-1.1% and +0.9%) group. Both groups exhibited hamstrings F200 (force produced in the first 200 ms) impairments following SS. Whereas BIASED participants exhibited an overall decrease (p < 0.05; 1.8% and 4.2%) in knee extension MVC, DECEPTION participants showed (p = 0.005; 8.8% and 5.1%) force increases. The quadriceps F200 was not significantly affected with the BIASED group but overall there were 4.5% and 8.7% F200 impairments at 1 and 5 min post-intervention (p = 0.05) with the DECEPTION group. Thus while deception resulted in enhanced quadriceps muscle force output, there was no knowledge or deception advantage when stretching the hamstrings.

Acute Effects of Different Anterior Thigh Self-Massage on Hip Range-of-Motion in Trained Men

“…responses to stretching interventions. 40 Furthermore, analgesia induced by techniques such as self-massage could have been mediated by autonomic nervous system (ANS) activity; 41 that is, a shift from sympathetic to parasympathetic tone. The mechanism behind this ANS shift remains unclear, but it can be hypothesized that certain hormones and neuropeptides may be at play given that massage has been associated with changes in stress hormones 42 (e.g., cortisol) and neuropeptides 9 (e.g., endogenous opioids, oxytocin and endocannabinoids), and that the aforementioned hormones and neuropeptides that are associated with a sympathetic shift also play a role in descending modulatory pathways, 43,44 which could account for changes in ROM.…”

No Effect of Muscle Stretching within a Full, Dynamic Warm-up on Athletic Performance

“…Common threats to external validity in previous studies include (a) total stretching durations being longer than those typically performed by athletes (17,18), (b) the stretching rarely being followed by other important components of a sport-specific warm-up, including high-intensity and movement pattern-specific exercises (1,19), even though it may mitigate the negative effects of stretching (20), (c) participants being only minimally familiarized with the tests (athletes, on the other hand, are familiar with their sporting skills), (d) differences existing in the execution (movement pattern) of static versus dynamic stretches, and (e) the imposition of nonstretching rest periods in control conditions/groups, which would not be performed in sports (4). Also, studies have been susceptible to serious threats to internal validity, such as the expectancy effects of knowledgeable participants (21) and lack of experimenter blinding (22).…”

Dynamic stretching alone can impair slower velocity isokinetic performance of young male handball players for at least 24 hours

“…All participants were verbally and vigorously encouraged to exert maximal effort during both MVCs. The peak force and the force exerted within the first 100ms of effort (instantaneous strength) were analyzed [10, 49, 50]. The prolonged effects of stretching on velocity specific isokinetic torque were also examined.…”