Page 70 - 《运动与健康科学》(英文)2024年第2期

TaggedAPTARAEnd192 A. Konrad et al.
ROM increase. When considering lower stretching volumes, ES (ES = 1.08) compared to periodically (ES = 0.75) or
changes in the perception to stretch or stretch tolerance (rather non-supervised (ES = 0.74) studies. Thus, future studies
than structural changes) are thought to be the mechanisms should take this into account and supervise participants
responsible for the increase in ROM following static stretch throughout the stretch intervention period.TaggedAPTARAEnd
training over several weeks. 8,28 TaggedAPTARAEnd TaggedAPTARAPConcerning the trained state of the participants, our
TaggedAPTARAPAlthough the changes in muscle structure (e.g., stiffness) subgroup analysis showed no significant difference in ROM
seem to be dependent on stretching volume, our meta-regres- adaptations between elite athletes, recreational athletes, or
sion showed no significant relation between total stretch dura- sedentary individuals due to stretch training (p = 0.74). Since it
2
tion and ES on ROM (R = 0.03; p = 0.73). The lack of a was shown that trained and untrained individuals might
dose response is likely due to the fact that many of the studies respond differently to a training stimulus (i.e., concurrent
conducted lower stretch durations (»1000 s), while only a few resistance and endurance training), 46 we would not have
looked at a more comprehensive stretch duration. Another expected similar adaptations. On the contrary, even the ESs
meta-analysis reported that the total stretching load had no within the groups were very similar and ranged from 1.253
impact on the magnitude of change in ankle ROM. 36 Even in a to 1.044. As we know that various training regimes (e.g.,
further meta-regression, we could not find a relation between strength training) can increase ROM, 47 future studies should
stretch frequency per week and the effects sizes on ROM take baseline flexibility levels into account when considering
2
(R = 0.02; p = 0.42). Based on these findings, it appears that trained status as a variable.TaggedAPTARAEnd
stretching with a high volume and/or high weekly frequency TaggedAPTARAPMoreover, we also compared sex-specific responses of
might not be mandatory to maximize gains in ROM in the stretch training on ROM. Although it was no surprise that
there was a significant difference in the subgroup analysis
general population.TaggedAPTARAEnd
TaggedAPTARAPStretching intensity was also considered as a potential (p = 0.036), we initially thought that males would show higher
moderating variable. An original study that directly compared ESs due to their lower baseline flexibility levels compared to
high-intensity stretching with low-intensity stretching (i.e., females. 39,48 However, our results show the opposite, namely,
without control groups) found a favorable ROM effect associ- significantly higher ESs in females (ES = 1.56) compared to
ated with the high-volume stretching techniques. 17 However, males (ES = 0.88). A potential explanation for these results
our subgroup analysis, which only took randomized controlled might be that females do not exhibit higher flexibility in all
trials into consideration, found no significant difference joints compared to males. McKay et al., 25 for example, found
between low- and high-intensity stretching in terms of ROM similar values in males and females in ankle dorsiflexion
gains. Our results indicate that it might not be necessary to ROM. Since the studies included in this meta-analysis
stretch to the pain threshold to maximize gains in ROM since frequently tested the ankle joint and found that at least the
with low intensity we found a significant moderate magnitude baseline values were equal, this is one potential explanation.
increase in ROM (ES = 0.92), while high-intensity stretching However, it could also be that females react more sensitively
only showed a marginally better ES result (ES = 1.02). In to stretch training than males.TaggedAPTARAEnd
contrast, the study done by Nakamura et al. 17 found significant TaggedAPTARAPIn terms of the individual muscles stretched, we saw no
differences between the intensities since the low-intensity significant difference in our subgroup analysis (p = 0.13).
protocol was 01 on a 11-point Verbal Numerical Scale Consequently, there seems to be no single muscle group that
compared to 67 for the high intensity. Hence, it can be produces the greatest ROM increase. However, the ESs for the
assumed that a higher intensity than 01 has to be applied to treated muscles range from 1.134 to 0.616, which indicates
get comparable results with a high-intensity approach. The some variation between muscle groups/joints. For example,
studies in our meta-analysis tended to recruit recreationally the ankle joint has a much more limited ROM than the hip or
49,50
active or trained subjects but not individuals who need extreme knee due to bone and ligament structures. We would
in ROM, such as gymnasts and figure skaters. The present find- assume this limits the potential for long-term increases in
ings regarding the insignificant effects of stretch intensity and ankle joint ROM. Indeed, by stretching the triceps surae, the
duration may not equally apply when extreme flexibility is the ankle joint ROM increase showed a lower effect (0.616)
goal; hence, further studies are needed to examine these compared to hip or knee ROM (<1.1) (i.e., by stretching the
hamstrings or hip flexors). With the joint anatomical differ-
distinct populations.TaggedAPTARAEnd
TaggedAPTARAPConcerning the supervision of the training, our subgroup ences contributing to greater ankle joint restriction, it may be
analysis showed no significant difference between fully super- difficult to compare stretch-induced changes at the ankle to
vised, periodically, or non-supervised studies. However, those at other joints, such as the hip. There may be a need for
concerning strength training regimes, it was reported that greater volumes or durations of stretch training with such
supervision can lead to superior results in outcome parameters restricted joints. We recommend that further research on
such as strength compared to non-supervised training muscle-specific adaptations is needed to obtain a clearer
regimes. 44,45 While it is likely most of the eligible studies in picture. Except for the quadriceps muscle and, hence, knee
our meta-analysis excluded non-committed participants, flexion flexibility, all treated muscles showed significant
meaning those who failed to perform a certain percentage of changes due to stretch training. A likely explanation for the
the stretch training, it should still be noted that the fully super- lack in changes to the quadriceps muscle might be that only
vised studies in our meta-analysis showed the highest 3 ESs were available.TaggedAPTARAEnd