Acute effects of static and dynamic stretching on hamstrings’ response times

The Effect of Spinal Asymmetries on Physical Fitness Parameters in Young Elite Soccer Players

The purpose of the study was to examine the effect of spinal asymmetries on specific physical fitness parameters in young elite soccer players. Fifty male soccer players, all members of the under 17 (U17) and 15 (U15) National teams of Cyprus, were initially evaluated for thoracic kyphosis, lumbar lordosis and scoliosis asymmetries. Based on the spinal asymmetries’ initial evaluation, soccer players were categorized into the asymmetry group (AG) and normal group (NG) per spinal asymmetry. Hamstring and lower-back flexibility, countermovement jump (CMJ) and lower body isokinetic maximum force were evaluated between AG and NG. CMJ with arm swing was lower in kyphotic posture AG compared with the NG (AG: 41.70 ± 3.59 cm, NG: 44.40 ± 4.34 cm; p = 0.028). Single leg CMJ was lower in both legs in scoliotic posture AG compared with the NG (right: AG: 17.42 ± 1.86 cm, NG: 19.16 ± 2.42 cm, p = 0.008, left: AG: 17.54 ± 1.33 cm, NG: 19.97 ± 2.91 cm; p = 0.002). Sit-and-reach flexibility was lower in scoliotic posture AG (AG: 20.44 ± 5.76 cm, NG: 24.82 ± 6.83 cm; p = 0.024) and higher in lordotic posture AG (AG: 25.95 ± 6.59 cm, NG: 21.73 ± 6.45 cm; p = 0.04) both compared with the NG. No significant difference was found for quadriceps and hamstrings concentric peak torque between the AG and NG (p > 0.05). The current study revealed that kyphotic and scoliotic posture asymmetries deteriorate neuromuscular explosiveness performance and diminish lower limbs’ flexibility in young International-level soccer players.

Kinematics and Esthetics of Grand Battement After Static and Dynamic Hamstrings Stretching in Adolescents

The objective of this study was to explore the effects of static and dynamic hamstring muscles stretching on kinematics and esthetics of grand battement (high velocity kicks) in adolescent recreational dancers. Sixteen participants were assessed before and immediately after both stretching modalities. Kinematics of movement was measured by an optoelectronic system and esthetics was scored by a jury of professional dancers. Both stretching modalities led to significant kinematic differences compared with without stretching. Significant linear correlations between kinematic parameters and esthetic scores have been observed: improving dancers' physical performances has noticeable impact on the perception of their movements.

Immediate effects of a direct myofascial release technique on hip and cervical flexibility in inactive females with hamstring shortening: A randomized controlled trial

BACKGROUND

Currently, greater background is required about the effectiveness of myofascial release (MFR) on muscle flexibility.

OBJECTIVE

Our goal was to determine the immediate effect of a direct MFR technique on hip and cervical flexibility in inactive females with hamstring shortening.

METHOD

The sample group included 68 female university students, randomly divided into a control group (n = 34) and an experimental group (n = 34). A placebo technique was used with the control group, and direct MFR on the posterior thigh region was used with the experimental group.

RESULTS

The mixed factorial ANOVA did not show significant intergroup differences (p > 0.05). In the experimental group, Bonferroni post hoc test showed significant intragroup differences between pre-test and post-test 1, as well as between pre-test and post-test 2 for the three ischiotibial muscle flexibility tests (p < 0.001). Cervical flexion range of motion showed significant differences between pre-test and post-test 1 (p < 0.001).

CONCLUSIONS

We conclude that the protocol based on a single direct MFR intervention was no more effective than the placebo in improving flexibility both locally at the hamstring level and remotely at the level of the cervical extensor muscles. Future research should consider different MFR techniques on the immediate increase in muscle flexibility and the long-term effect of MFR, as well as consider different intervention groups.

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

There are many adult studies reporting static stretch (SS)-induced deficits and dynamic stretch (DS) performance improvements shortly after the intervention. However, there is only a single study examining stretch-induced performance changes with youth at 24 hours' post-stretch. The objective of this study was to examine physiological responses of young trained athletes at 24-hours after experiencing SS or DS protocols. Eight young male, elite handball players (age: 16.1±5.1 years) were tested prior to-, 3-minutes and 24-hours following the three conditions (DS, SS, Control) in a randomized and counterbalanced order. Similar volumes of SS (2 repetitions of 75s for each leg) and DS (5 repetitions of 30s for each leg) involved one stretch each for the quadriceps and hamstrings. Tests included (i) two 4s maximal voluntary isometric contractions (MVC) at 60° of knee flexion with 2-min rest, (ii) two maximal isokinetic contractions each at 60°/sec and 300°/sec with 1-min rest, and (iii) two drop jumps with 30-sec rest. To simulate a full warm-up, dynamic activity including 5 minutes of aerobic cycling (70 rpm; 1 kilopond), 4 submaximal isometric contractions and 4 drop jumps were instituted before the pre-tests and following the interventions. Two-way repeated measures ANOVAs revealed that 1) both the SS and control conditions exhibited knee extensor 60°.s-1 (SS:-10.3%; p = 0.04, Control: -8.7%; p = 0.07) and 300°.s-1 (SS: -12.9%; p = 0.005, Control: -16.3%; p = 0.02) isokinetic deficits at post-test, 2) DS impaired knee flexor 60°.s-1 isokinetic work and power-related measures at post-test (Work: -10.1%; p = 0.0006; Power: -19.1%; p = 0.08) and at 24-hours' post-test (Work: 9.9%; p = 0.023; Power: -9.6%; p = 0.01), 3) DS (12.07% and 10.47%) and SS (13.7% and 14.6%) enhanced knee flexor 300°.s-1 isokinetic force and power-related measures compared to control. In conclusion, testing-induced knee extensor isokinetic impairments were counterbalanced by DS, however the hip flexion DS could have produced minor muscle damage for at least 24-hours decreasing knee flexor forces and power at 60°.s-1.

Acute effects of cyclic versus static stretching on shoulder flexibility, strength, and spike speed in volleyball players

Objectives

This study aims to examine the acute effects of cyclic stretching versus static stretching on the shoulder flexibility, rotator cuff muscle strength, spike speed, and spike hit rate on target in adolescent volleyball players.

Materials and methods

A total of 36 female volleyball players aged between 13 and 15 years were included in this study. Volleyball players were randomly divided into three groups: cyclic stretching group, static stretching group, and control group. Shoulder flexibility, rotator cuff muscle strength, spike speed, and spike hit rate on target were measured before and after the intervention.

Results

Shoulder flexibility increased in cyclic stretching and static stretching groups after the intervention. Internal rotation strength increased in cyclic stretching group after the stretching intervention, compared to the control group. A significant reduction was observed in the scapular plane abduction strength in static stretching group after the intervention.

Conclusion

Our study results suggest that cyclic stretching may be beneficial, as it increases both the shoulder flexibility and strength of young female volleyball players. In terms of volleyball performance, it can not be declared both cyclic stretching and static stretching have any effect.

Acute effects of muscle stretching on physical performance, range of motion, and injury incidence in healthy active individuals: a systematic review

Recently, there has been a shift from static stretching (SS) or proprioceptive neuromuscular facilitation (PNF) stretching within a warm-up to a greater emphasis on dynamic stretching (DS). The objective of this review was to compare the effects of SS, DS, and PNF on performance, range of motion (ROM), and injury prevention. The data indicated that SS- (-3.7%), DS- (+1.3%), and PNF- (-4.4%) induced performance changes were small to moderate with testing performed immediately after stretching, possibly because of reduced muscle activation after SS and PNF. A dose-response relationship illustrated greater performance deficits with ≥60 s (-4.6%) than with <60 s (-1.1%) SS per muscle group. Conversely, SS demonstrated a moderate (2.2%) performance benefit at longer muscle lengths. Testing was performed on average 3-5 min after stretching, and most studies did not include poststretching dynamic activities; when these activities were included, no clear performance effect was observed. DS produced small-to-moderate performance improvements when completed within minutes of physical activity. SS and PNF stretching had no clear effect on all-cause or overuse injuries; no data are available for DS. All forms of training induced ROM improvements, typically lasting <30 min. Changes may result from acute reductions in muscle and tendon stiffness or from neural adaptations causing an improved stretch tolerance. Considering the small-to-moderate changes immediately after stretching and the study limitations, stretching within a warm-up that includes additional poststretching dynamic activity is recommended for reducing muscle injuries and increasing joint ROM with inconsequential effects on subsequent athletic performance.

Electromechanical delay of the hamstrings during eccentric muscle actions in males and females: Implications for non-contact ACL injuries

Sex differences in neuromuscular functioning has been proposed as one of the factors behind an increased relative risk of non-contact anterior cruciate ligament (ACL) injury in females. The aim of this study was to explore sex differences in electromechanical delay (EMD) of the hamstring muscles during eccentric muscle actions and during a range of movement velocities. This study recruited 110 participants (55 males, 55 females) and electromyography of the semitendinosus, semimembranosus and biceps femoris was determined during eccentric actions at 60, 120 and 240°/s. No significant sex differences were observed irrespective of muscle examined or movement velocity. Irrespective of sex EMD significantly increased with increasing movement velocity (P < 0.01). There was no significant difference in the EMD of the 3 muscles examined. Our findings suggest that during eccentric actions of the hamstrings that there are no sex differences, irrespective of movement velocity. This would suggest that other factors are probably responsible for the increased relative risk of non-contact ACL injury in females compared to males.