ECSS Paris 2023: CP-BM03
INTRODUCTION: Static stretching (SS) techniques have been shown to improve a joint’s range of motion (ROM), both acutely after one bout of stretching and chronically after stretch training for several weeks. Furthermore, acute static stretching can also improve the flexibility of non-adjacent joints, for example, the contralateral joint, or on a heterologous region (i.e. increase in ROM in lower body ROM when stretching upper body). However, to our best knowledge, there is no evidence of an increase in ROM in heterologous regions after a chronic intervention of static stretching. This study aimed to investigate the effects of 7 weeks of static stretching of the Pectoralis Major muscle on ankle dorsiflexion range of motion METHODS: Thirty-three participants were divided into two groups (intervention n=18; control n=15), and their ankle dorsiflexion ROM was assessed before and after a 7-week intervention program. Ankle dorsiflexion ROM was passively assessed with a dynamometer device (Con Trex Mj, CMV AG, Dübendorf, Switzerland) in both groups. The intervention consisted of three static stretching exercises for the Pectoralis Major performed three times a week for 5 minutes each (total stretching time = 15 minutes) with an intensity at the point of discomfort. The control group did not perform any additional stretching exercises besides their normal exercise routine. RESULTS: Analysis of Variance revealed no significant changes between groups as well as between pre-and post-intervention. CONCLUSION: There is vast evidence that a single bout of SS can increase ROM of non-stretched body regions, either due to strain transfer along myofascial chains, or to an increase in global pain perception. However, our data did not show significant long-term changes in this regard. This suggests that, if the objective is to improve the range of motion in a particular joint, the advisable would be to intervene in the involved muscle with exercises targeting the enhancement of ROM, such as stretching or resistance training.
Read CV Josefina Manieu SeguelECSS Paris 2023: CP-BM03
INTRODUCTION: In sports settings, dynamic stretching (DS) is used to prevent injury and enhance sports performance. Many previous studies reported that the joint range of motion (ROM) increases immediately after DS (1, 2). Muscle stiffness is one of the elements constituting the ROM; however, as far as we know, it is unclear whether DS affects muscle stiffness. The purpose of this study was to determine the changes in muscle shear modulus following DS. METHODS: The participants comprised 13 healthy young men (20.9 ± 1.8 years, 172.3 ± 4.8 cm, 65.9 ± 8.9 kg). They performed DS of right hip flexors in the supine position, completing 8 sets of 30-second with 60 seconds rest interval. The shear moduli of the biceps femoris long head (BFlh) were measured before DS, after 4 sets of DS (4DS), and after 8 sets of DS (8DS) using ultrasonic shear wave elastography. In addition, ROMs were measured before DS and after 8DS using Biodex, and the initial position was the hip flexed at 120° and knee flexed at 90° in a supine position. The ROM was defined as the maximum angle achieved by movement of only knee extension. A one-way repeated measures analysis of variance (ANOVA) and Bonferroni’s post hoc test were used to determine the effects of DS on the shear modulus of the BFlh, and a paired t-test was used to determine the effect of DS on ROM. RESULTS: The ANOVA showed the main effect of time and Bonferroni’s post hoc tests showed that the shear moduli after 4DS (36.9 ± 16.6 kPa) and 8DS (36.1 ± 11.6 kPa) were significantly higher than before DS (31.2 ± 15.2 kPa) (both p < 0.01). On the other hand, there was no significant difference in shear modulus after 4DS and after 8DS (p = 1.00). The ROM was significantly higher after 8DS than before DS (p = 0.02). CONCLUSION: Our results suggest the DS of hip flexors increases the shear modulus of the BFlh. On the other hand, the DS of that increased ROM. Further research is needed to examine the mechanism by that DS increases muscle stiffness while simultaneously increasing ROM. References (1) Iwata et al., J Sports Sci Med, 2019 (2) Matsuo et al, J Sports Sci Med. 2023 Contact cgtg0146@mail4.doshisha.ac.jp
Read CV Raira SakamotoECSS Paris 2023: CP-BM03
INTRODUCTION: The function of the gluteus maximus(GM) is very important in sports and daily activities. The GM has complex functions and many exercise methods, if it is not practiced properly, it may cause fatigue and injury in the lower limbs and waist, while the GM is not exercised enough. In order to improve the exercise efficiency of the GM, this paper aims to find the exercise that activatie the GM more while activating the waist and lower limbs less. METHODS: Thirteen healthy subjects performed 24 types of no load GM exercises: static gluteal bridge (twice, pre and post the test), dynamic gluteal bridge, shoulder raise gluteal bridge, frog gluteal bridge, one-leg gluteal bridge, side bridge, single-leg side bridge, side-lying hip abduction, kneeling hip abduction (leg up and bend the knee), prone hip extension (legs lift),prone hip extension (frog pose), mid-back extension, kneeling hip extension (leg lift and bent knee), Kneeling hip extension (leg lift straightly), squat, sumo squat, bulgarian squat, lunge squat, front lunge, back lunge, side lunge, knee bend deadlift, straight-leg deadlifts,single-leg deadlifts. Repeat each exercise 5 times for 2s each time; Take a 3min break between exercise. Surface EMG of GM, erector spinae (lumbar,ES), biceps femoris(BF), and vastus lateralis(VL) were acquired. The root mean square (RMS) of each subjects dynamic gluteal bridge was defined as the benchmark, and the RMS of each exercise was divided by the benchmark, which was called normalized RMS of the exercise. Reliability was estimated by the intraclass correlation coefficient (ICC)from RMS of the two static gluteal bridges pre and post the experiment to exclude the influence of fatigue. One-way ANOVAs was used to test the differences between the normalized RMS and activation ratios of each exercise and the gluteal bridge. RESULTS: The ICC of RMS values of the two static gluteal bridges pre and post the experiment is 0.83, which indicate that the GM had no fatigue during the test, and the results were reliable. The normalized RMS of GM of each exercise ranged form 0.70 to 2.83, and the prone hip extension (frog pose) was maximal (2.83±1.48, P=0.000). The GM/ES activation ratio ranged from 0.29 to 1.93, the kneeling hip abduction (leg up and bend the knee) was maximal (1.93±1.87, P=0.000), and the prone hip extension (frog pose) was the third (1.16±1.00, P=0.212). The activation ratio of GM/VL was 0.33 to 6.63, and the prone hip extension (frog pose) was maximal (6.63±4.42, P=0.000). The activation ratio of GM/BF was 0.54 to 1.63, the hip abduction was maximal in all the lying exercise (1.63±1.70, P=0.173), and the fifth in the prone hip extension (frog pose) (1.26±0.63, P=0.910). CONCLUSION: Among the 24 common GM exercises, the prone hip extension (frog pose) has the maximal activation degree for GM, and lower activation degree of erector spinae, vastus lateralis and biceps femoris.It will develop the GM More specialized, and cause less fatigue on nearby muscles.
Read CV ji xiaoleiECSS Paris 2023: CP-BM03