Acute effects of constant torque and constant angle stretching on the muscle and tendon tissue properties

Abstract

PurposeStatic stretching induces acute structural changes of the muscle–tendon unit (MTU) that are related to the intensity or duration of stretching. It has been reported that stretching with a constant torque (CT) leads to greater joint range of motion changes than stretching with a constant angle (CA). Whether or not this difference is due to different structural changes of the MTUs of the lower leg and ankle plantar flexors is not known. Therefore, the purpose of this study was to compare the acute effects of single CA and CT stretching on various muscle and tendon mechanical properties.MethodSeventeen young, healthy volunteers were tested on two separate days using either CT or CA stretching (4 × 30 s each). Before and after stretching, dorsiflexion range of motion (RoM), passive resistive torque (PRT), and maximum voluntary contraction (MVC) were measured with a dynamometer. Ultrasonography of the medial gastrocnemius (GM) muscle–tendon junction (MTJ) displacement allowed us to determine the length changes in the tendon and muscle, respectively, and hence to calculate their stiffness.ResultsMaximum dorsiflexion increased while PRT, muscle–tendon stiffness, and muscle stiffness decreased following both CA and CT stretching. There was a greater increase in RoM following CT stretching compared to CA stretching. Moreover, the decline in PRT was greater during CT stretching compared to CA stretching. As expected, several functional adaptations (RoM, PRT) were different between CT and CA stretching due to the higher intensity of CT stretching. However, no structural differences in the adaptations to the stretching modalities could be detected.ConclusionWe suggest that the different functional adaptations between CA and CT stretching are the consequence of different adaptations in the perception of stretch and pain.

The acute time course of muscle and tendon tissue changes following one minute of static stretching

“…PRT was not changed at any time point after the single static stretching exercise. This is in accordance with some other studies (Magnusson, Aagard, Simonsen, & Bojsen-Møller 1998), but not all the previous studies dealing with similar (Kay et al, 2015;Opplert et al, 2016) or higher durations of stretching (Kay & Blazevich, 2009;Konrad et al, 2017a;2017b;2019;Konrad & Tilp, 2020;Nakamura, Ikezoe, Takeno, & Ichihashi, 2013;Opplert et al, 2016). The controversial results of Kay et al (2015), who also considered 1 min of total stretching, might be explained by the different stretching approaches.…”

“…#= significant difference in analysis of variance, * = significant difference to pre-value data, mean ±SD. (Herda, Cramer, Ryan, McHugh, & Stout, 2008;Marek et al, 2005;Konrad et al, 2019) have reported a decrease in maximum strength performance following a single static stretching exercise, the results of others and the current study suggest that the maximum performance is not negatively affected (Konrad et al, 2017a;Konrad & Tilp, 2020;Kubo et al, 2001;Zakas, Doganis, Papakonstandinou, Sentelidis, & Vamvakoudis, 2006). These controversial results could possibly be explained by the differences in overall stretch duration, as summarized in the reviews by Kay and Blazevich (2012) and Behm et al (2016), who pointed out that only stretching for 60 s or longer can induce a detrimental effect on maximum performance.…”

“…The ultrasound probe was attached to the lower leg with a custom-built styrofoam block and secured with elastic bands to prevent any displacement of the probe. The previous studies (Konrad et al, 2017a;Stafilidis and Tilp, 2015), confirmed that this kind of fixation of the ultrasound probe did not lead to any unwanted shifts of the probe during the measurement. To determine the muscle displacement during PRT measurement, the echoes of the MTJ in the ultrasound videos were manually tracked (Kato et al, 2010).…”

“…While Kay et al (2015) adapted the joint angle after every 15 s bout of stretching, in the current study, stretching with constant joint angle was performed. In a previous study, we demonstrated that the adapted-angle stretching applied by Kay et al (2015) is a more efficient way to decrease PRT (and increase RoM) than the constant-angle stretching applied in the present study (Konrad et al, 2017a). Additionally, we have to mention that the level of significance for PRT indicates a tendency toward a decrease (P = 0.08, see Table 1).…”

“…Kay, Husbands-Beasley and Blazevich (2015) reported decreased muscle stiffness (and no changes in tendon stiffness) following 4 × 15 s of static stretching, which could ex-plain the decrease in peak moment reported in Kay and Blazevich (2008). Decreased muscle stiffness following a single static stretching exercise has also been reported (Kay & Blazevich, 2009;Konrad, Budini, & Tilp, 2017a;Konrad, Stafilidis, & Tilp, 2017b), but not by all authors (Kato, Kanehisa, Fukunaga, & Kawakami, 2010;Kubo, Kanehisa, Kawakami, & Fukunaga, 2001) who tried to find the mechanism behind the increase in RoM and a possible decrease in performance. Far fewer studies are available that analyzed the time course of the changes of different parameters of the muscletendon function and structure following the stretching.…”