Flexibility and achilles tendon: a brief review / Flexibilidade e tendão de aquiles: uma breve revisão

Performing flexibility training in an exercise program is important to improve range of motion (ROM). Tendons have a profound impact on the general function of the musculoskeletal system, influence the limitation of ROM, and its structure and mechanical properties can benefit from stretching protocols. The systematic use of lower limbs in locomotion caused the Achilles tendon to become the largest and strongest tendon in the human body. Therefore, understanding the best prescription and frequency of flexibility exercise leads to changes in tendon properties is essential for an appropriate and effective exercise routine. Thus, the aim of this review was to organize and discuss publications about the implications of triceps surae stretching in ROM, as well as its influence on tendon properties. Acute studies show that continuous stretching times between five and 10 minutes cause decreased tendon stiffness, which is not seen in fractionated stretching times less than five minutes. Chronic studies, in turn, also don't present significant results in stiffness with fractionated times and studies with continuous times were not found. Thus, it is not possible to know if a continuous stretching time (longer than one minute) or a total time longer than five minutes but fractionated, can influence the tendon stiffness. (AU)

A realização de treino de flexibilidade como rotina em um programa de exercícios é importante para melhorar amplitude de movimento (ADM). Os tendões têm um impacto profundo na função geral do sistema musculoesquelético, influenciam na limitação da ADM, e sua estrutura e propriedades mecânicas podem se beneficiar de protocolos de alongamento. O uso sistemático dos membros inferiores na locomoção fez com que o tendão de Aquiles se tornasse o maior e mais forte tendão do corpo humano. Portanto, entender qual a melhor prescrição e frequência de exercício de flexibilidade para que ocasione alterações nas propriedades tendíneas é essencial para uma rotina de exercícios adequada e eficaz. Sendo assim, o objetivo dessa revisão de literatura foi organizar e discutir publicações sobre as implicações do alongamento do tríceps sural na ADM, bem como sua influência nas propriedades tendíneas. Estudos agudos mostram que tempos contínuos entre cinco e 10 minutos de alongamento estático causam diminuição da rigidez tendínea, o que não é visto em tempos intervalados inferiores a cinco minutos. Os estudos crônicos, por sua vez, também não apresentam resultados significativos na rigidez com protocolos de alongamento intervalados e estudos com protocolos contínuos não foram encontrados. Dessa forma, não é possível saber se um tempo contínuo de alongamento (superior a um minuto) ou um tempo superior a cinco minutos, intervalado, podem influenciar na rigidez tendínea. (AU)

Triceps surae muscle-tendon unit mechanical property changes during 10 minutes of streching.

OBJECTIVE: To verify the effect of 10-min static stretching on the triceps surae mechanical properties. DESIGN: Quasi-experimental one-group pre test-post test study compared the time points of before, after, and minute by minute of one session of triceps surae passive static stretching. METHODS: 15 participants performed a 10-min plantar flexor passive static stretching on the isokinetic dynamometer. We evaluated passive torque and myotendinous junction (MTJ) displacement before, minute by minute, and after the intervention. In contrast, we evaluated the range of motion (ROM), passive torque, MTJ displacement, and hysteresis before and after the intervention. Paired t-test compared pre and post-intervention time points. Passive torque and MTJ displacement in the minute-by-minute evaluations were compared by repeated measures one-way ANOVA with a Bonferroni post-hoc test. RESULTS: ROM increased (effect size d = 0.56) and passive torque and muscle-tendon unit stiffness decreased (effect size d = 0.65 and d = 0.73, respectively) post-stretching. There was a reduction only in passive torque in the minute-by-minute evaluation, mainly at minutes five and seven. CONCLUSIONS: passive torque decreased over a 10-min static stretching session of the ankle plantar flexors, followed by a ROM increase and muscle-tendon unit, a stiffness decrease.

Proprioceptive Training on Dynamic Neuromuscular Control in Fencers: A Clinical Trial.

CONTEXT: Fencing is a sport of agility, with a higher incidence of lower-limb injuries, of which the ankle sprain is the most prevalent. Injury prevention is very important to improve performance and decrease the withdrawal time of athletes. Proprioceptive training programs can be added to the training of athletes, since, in addition to easy application and low cost, proprioception has the function of stabilizing the ankle joint to prevent injuries. OBJECTIVE: To verify the influence of a 12-week proprioceptive training program on dynamic neuromuscular control in fencing athletes. DESIGN: The study was a clinical trial, and the athletes were allocated, for convenience, in the intervention group or in the control group. SETTING: The study was developed in 4 stages (preintervention, intervention, postintervention, and follow-up of 3). The neuromuscular control during the star excursion balance test was evaluated. PARTICIPANTS: The participants were 19 fencing athletes (intervention group: 10, and control group: 9), aged 14-35 years, from a multisport club. INTERVENTIONS: The athletes performed the proprioceptive training during 12 weeks, 3 times a week, with a duration of 30 minutes. MAIN OUTCOME MEASURES: Dynamic neuromuscular control. RESULTS: The data and SE were considered for statistical analysis, submitted to the generalized estimates equations test with Bonferroni post hoc. The level of significance was .05. The distance reached in the star excursion balance test increased significantly in all 8 directions evaluated in the 2 legs of the intervention group. CONCLUSIONS: The proprioceptive training program was able to improve dynamic neuromuscular control in fencing athletes.

Effects of proprioceptive training on the incidence of ankle sprain in athletes: systematic review and meta-analysis.

OBJECTIVE:: To investigate how dynamic neuromuscular control, postural sway, joint position sense, and incidence of ankle sprain are influenced by balance training in athletes compared with the control group in randomized clinical trials. DATA SOURCES:: The search strategy included MEDLINE, Physical Therapy Evidence Database, Cochrane Central Register of Controlled Trials, and Latin American and Caribbean Center on Health Sciences Information. Randomized controlled trials (RCTs) were published by June of 2018. METHODS:: RCTs that evaluate the effectiveness of proprioception in these outcomes: dynamic neuromuscular control, postural sway, joint position, and the incidence of ankle sprains in athletes aged between 18 and 35 years. Two reviewers independently screened the searched records, extracted the data, and assessed risk of bias. The treatment effect sizes were pooled in a meta-analysis using the RevMan 5.2 software. Internal validity was assessed through topics suggested by Cochrane Collaborations. RESULTS:: Of the 12 articles included ( n = 1817), eight were in the meta-analysis ( n = 1722). The balance training reduced the incidence of ankle sprains in 38% compared with the control group ( RR: 0.62; 95% CI: 0.43-0.90). In relation to the dynamic neuromuscular control, the training showed increase in the distance of reach in the anterior (0.62 cm, 95% CI: 0.13-1.11), posterolateral (4.22 cm, 95% CI: 1.76-6.68), and posteromedial (3.65 cm, 95% CI: 1.03-6.26) through the Star Excursion Balance test. Furthermore, training seems to improve postural sway and joint position sense. CONCLUSION:: Balance training reduces the incidence of ankle sprains and increases dynamic neuromuscular control, postural sway, and the joint position sense in athletes.

Full Range of Motion Induces Greater Muscle Damage Than Partial Range of Motion in Elbow Flexion Exercise With Free Weights.

Baroni, BM, Pompermayer, MG, Cini, A, Peruzzolo, AS, Radaelli, R, Brusco, CM, and Pinto, RS. Full range of motion induces greater muscle damage than partial range of motion in elbow flexion exercise with free weights. J Strength Cond Res 31(8): 2223-2230, 2017-Load and range of motion (ROM) applied in resistance training (RT) affect the muscle damage magnitude and the recovery time-course. Because exercises performed with partial ROM allow a higher load compared with those with full ROM, this study investigated the acute effect of a traditional RT exercise using full ROM or partial ROM on muscle damage markers. Fourteen healthy men performed 4 sets of 10 concentric-eccentric repetitions of unilateral elbow flexion on the Scott bench. Arms were randomly assigned to partial-ROM (50-100°) and full-ROM (0-130°) conditions, and load was determined as 80% of 1 repetition maximum (1RM) in the full- and partial-ROM tests. Muscle damage markers were assessed preexercise, immediately, and 24, 48, and 72 hours after exercise. Primary outcomes were peak torque, muscle soreness during palpation and elbow extension, arm circumference, and joint ROM. The load lifted in the partial-ROM condition (1RM = 19.1 ± 3.0 kg) was 40 ± 18% higher compared with the full-ROM condition (1RM = 13.7 ± 2.2 kg). Seventy-two hours after exercise, the full-ROM condition led to significant higher soreness sensation during elbow extension (1.3-4.1 cm vs. 1.0-1.9 cm) and smaller ROM values (97.5-106.1° vs. 103.6-115.7°). Peak torque, soreness from palpation, and arm circumference were statistically similar between conditions, although mean values in all time points of these outcomes have suggested more expressive muscle damage for the full-ROM condition. In conclusion, elbow flexion exercise with full ROM seems to induce greater muscle damage than partial-ROM exercises, even though higher absolute load was achieved with partial ROM.

Acute effect of different time periods of passive static stretching on the hamstring flexibility.

BACKGROUND: Several factors are associated with the presence of chronic low back pain; one of them is the flexibility of the hamstring muscles that influences the posture of the pelvic spine. OBJECTIVE: Investigate the influence of two different time periods of passive static stretching on the flexibility of the hamstring. METHODS: Forty-six physiotherapy students were divided into two groups performing stretching exercises: 30 s and 60 s duration. The collections consisted of: (1) pre-test: evaluation of the flexibility of the hip and knee, using a manual goniometer by means of the following tests: Straight Leg Raise Test (SLR), Passive Hip Flexion Test (PHFT) and Modified Knee Extension Test (MKET), (2) intervention: stretching with different runtimes, (3) post-test: reappraisal of flexibility, conducted immediately after the intervention. RESULTS: Significant difference was observed intra groups, group that did stretching exercises lasting 30 seconds (G30) (SLR p = 0.000. PHFT p = 0.003 and MKET p = 0.000) and group that did stretching exercises lasting 60 seconds (G60) (SLR p = 0.000. PHFT p = 0.001 and MKET p = 0.002). Comparing the groups, no significant difference was found (SLR p = 0.307; PHFT p = 0.904; MKET p = 0.132). CONCLUSION: Thus it can be inferred that 30 seconds are sufficient for increased flexibility of young women. Therefore the time-treatment sessions can be optimized. Only the acute effect of stretching was observed; further investigation of the long-term effect is required.

Influence of static stretching on hamstring flexibility in healthy young adults: Systematic review and meta-analysis.

The aim of the current study was to investigate the influence of static stretching on hamstring flexibility in healthy young adults by means of systematic review and meta-analysis. The search strategy included MEDLINE, PEDro, Cochrane CENTRAL, EMBASE, LILACS, and manual search from inception to June 2015. Randomized and controlled clinical trials studies that have compared static stretching to control group, and evaluated range of motion (ROM), were included. On the other hand, studies that have worked with special population such as children, elderly people, athletes, and people with any dysfunction/disease were excluded, as well as articles that have used contralateral leg as control group or have not performed static stretching. The meta-analysis was divided according to three types of tests. Nineteen studies were included out of the 813 articles identified. In all tests, the results favored static stretching compared to control group: passive straight leg raise (12.04; 95% CI: 9.61 to 14.47), passive knee extension test (8.58; 95% CI: 6.31 to 10.84), and active knee extension test (8.35; 95% CI: 5.15 to 11.55). In conclusion, static stretching was effective in increasing hamstring flexibility in healthy young adults.