Francisco Ayala

Chronic flexibility improvement after 12 week of stretching program utilizing the ACSM recommendations: hamstring flexibility.

The ACSM flexibility training recommendations emphasize proper stretching of muscles supporting the major joints, but there is a little evidence to support this recommendation in terms of effectiveness, and which stretching parameters (technique and single stretch duration) are more adequate. A randomized controlled clinical trial design was use to investigate whether the ACSM flexibility training recommendation parameters improve hip flexion range of motion. A total of 173 subjects, 122 men (21.3+/-2.5 years; 176.33+/-8.35 cm; 74.42+/-10.80 kg) and 51 women (20.7+/-1.6 years; 163.43+/-6.57 cm; 60.12+/-7.88 kg), classified as recreationally active young adult university students were randomly assigned to 1 of 7 groups: 1 control group (no stretching) or 1 of 6 stretching groups. All stretching groups performed 12 weeks of flexibility training with a consistent stretch daily dose (180 s) and frequency (3 days per week) parameters and different stretch technique (passive or active) and single stretch duration (15, 30, or 45 s). Hip flexion passive range of motion (PROM) was determined through the bilateral straight-leg raise test before, during (at 4 and 8 weeks), and after the program (12 weeks). All stretching groups performed hip flexion PROM after flexibility training. A significant improvement was identified in mean PROM for each stretching group, but no significant differences were found between stretch technique and single stretch duration (p>0.05). The control groups mean PROM decreased (Delta PROM: -0.08 degrees, 95% confidence interval [CI]=-2.3 to 5.3), whereas all stretching groups increased PROM (Delta PROM: 15.14 degrees, 95% CI=10.19 to 23.56) in hip flexion after 12 weeks of stretching (p<0.05). The present study suggests that the current ACSM flexibility training recommendations are effective for improving hip flexion ROM in recreationally active young adults.

Comparison of active stretching technique in males with normal and limited hamstring flexibility

OBJECTIVEn(1) to analyse the accumulative effects of a 12-week active stretching program on hip flexion passive range of motion (HF-PROM), and (2) to compare whether participants with different PROM baseline scores (normal and limited hamstring flexibility) respond in the same way to stretching.nnnDESIGNnRepeated measures design.nnnSETTINGnControlled laboratory environment.nnnPARTICIPANTSn138 males were categorized according to hamstring flexibility in the unilateral passive straight-leg raise test (PSLR) and assigned to one of two groups: normal hamstring flexibility (≥80°) or limited hamstring flexibility (<80°). In each group, participants were randomly distributed into one of two treatment subgroups: (a) control or (b) active stretching. The active stretching subgroups performed 12 weeks of flexibility training, the control subgroups did not stretch.nnnMAIN OUTCOME MEASURESnHF-PROM was determined through the PSLR test.nnnRESULTSnBoth stretching subgroups significantly improved (pxa0<xa00.01) their HF-PROM from baseline. The control subgroups did not.nnnCONCLUSIONSn12 weeks of an active stretching program performed 3 days per week with a daily stretch dose of 180xa0s improved HF-PROM in both populations (normal and limited hamstring flexibility). The stretching program was equally effective in terms of absolute improvement values for males with normal and limited hamstring flexibility.

Test-retest reliability of seven common clinical tests for assessing lower extremity muscle flexibility in futsal and handball players

OBJECTIVEnTo determine the inter-session reliability of seven lower limb muscle flexibility measures obtained from the passive hip extension test (PHE), passive hip flexion test (PHF), passive hip abduction test (PHA), passive straight leg raise test (PSLR), modified Thomas test (MTh), the ankle dorsi-flexion with knee extended (ADFKE) and flexed (ADFKF) tests.nnnDESIGNnRepeated measures design.nnnSETTINGnControlled laboratory environment.nnnPARTICIPANTSn60 futsal and 30 handball players.nnnMAIN OUTCOME MEASURESnReliability was examined through the change in the mean (ChM), standard error of measurement expressed in absolute values (SEM) and as a percentage of the mean score (%SEM), minimal detectable change (MDC95), and intraclass correlation coefficient (ICC2,k).nnnRESULTSnThe findings showed negligible ChM values for all the flexibility measures analysed (<1°). Furthermore, the SEM and MDC95 for each flexibility measure ranged from 1.3° to 2.5° and from 3.8° to 6.9°, respectively, with %SEM scores lower than 10% and ICC scores higher than 0.88.nnnCONCLUSIONSnClinicians can be 95% confident that an observed change between 2 measures larger than 3.7°, 6.2°, 5.5°, 6.1°, 6.9°, 4.7°, and 5.0° for the flexibility measures obtained from the PHE, PHF, PHA, PSLR, MTh, ADFKE and ADFKF, respectively, likely indicates a real change in muscle flexibility.

Reproducibility and Concurrent Validity of Hip Joint Angle Test for Estimating Hamstring Flexibility in Recreationally Active Young Men

Abstract Ayala, F, Sainz de Baranda, P, De Ste Croix, M, and Santonja, F. Reproducibility and concurrent validity of hip joint angle test for estimating hamstring flexibility in recreationally active young men. J Strength Cond Res 26(9): 2372–2382, 2012—The purposes of this study were twofold: (a) to examine the test-retest reproducibility and concurrent validity of the horizontal hip joint angle test (H-HJA) and vertical hip joint angle test (V-HJA) for estimating hamstring flexibility measured with an inclinometer during the passive straight-leg raise test (PSLR) and (b) to determine whether the H-HJA cutoff scores may be used for V-HJA for the detection of short hamstring flexibility in active recreationally young adults. Fifty young men underwent the H-HJA, V-HJA, and PSLR on the right and left legs 3 times in a randomized order with a 4-week interval between trials under a controlled laboratory environment. Reproducibility was examined using coefficient of variation (CV) and intraclass correlation coefficient (ICC3,1) and their respective confidence limits. Regression and kappa correlation analyses were performed to examine the association of H-HJA and V-HJA with the PSLR test, and the 95% limits of agreement between H-HJA and V-HJA were calculated to check if there were differences in the raising scores. The results demonstrated acceptable reproducibility measures for the H-HJA (4.12% CV; 0.93 ICC), V-HJA (4.99% CV; 0.92 ICC), and PSLR (4.83% CV; 0.88 ICC). The H-HJA (R2 = 0.62) and V-HJA (R2 = 0.63) results were significantly associated with those of the PSLR. The 95% limits of agreement between the H-HJA and V-HJA reported systematic bias (+7.12 cm) and a wide 95% random error ( ±13.72 cm). This study concluded that the test-retest reproducibility of the H-HJA, V-HJA, and PSLR is acceptable and that the validity of H-HJA and V-HJA is moderate. Furthermore, the H-HJA cutoff scores should not be used for V-HJA for the detection of short hamstring muscles in young adults.

Absolute reliability of isokinetic knee flexion and extension measurements adopting a prone position

The main purpose of this study was to determine the absolute and relative reliability of isokinetic peak torque (PT), angle of peak torque (APT), average power (PW) and total work (TW) for knee flexion and extension during concentric and eccentric actions measured in a prone position at 60, 180 and 240° s−1. A total of 50 recreational athletes completed the study. PT, APT, PW and TW for concentric and eccentric knee extension and flexion were recorded at three different angular velocities (60, 180 and 240° s−1) on three different occasions with a 72‐ to 96‐h rest interval between consecutive testing sessions. Absolute reliability was examined through typical percentage error (CVTE), percentage change in the mean (ChM) and relative reliability with intraclass correlations (ICC3,1). For both the knee extensor and flexor muscle groups, all strength data (except APT during knee flexion movements) demonstrated moderate absolute reliability (ChM < 3%; ICCs > 0·70; and CVTE < 20%) independent of the knee movement (flexion and extension), type of muscle action (concentric and eccentric) and angular velocity (60, 180 and 240° s−1). Therefore, the current study suggests that the CVTE values reported for PT (8–20%), APT (8–18%) (only during knee extension movements), PW (14–20%) and TW (12–28%) may be acceptable to detect the large changes usually observed after rehabilitation programmes, but not acceptable to examine the effect of preventative training programmes in healthy individuals.

A simplified version of the weight-bearing ankle lunge test: description and test-retest reliability.

The purpose of this study was twofold: (1) to describe a new version of the weight-bearing ankle lunge test (WBLT) that is simple to administer, that allows clinicians and sports medicine practitioners to directly assess (in degrees) the ankle dorsiflexion range of motion in a very short period of time while adopting a comfortable testing position; as well as (2) to determine the test-retest reliability of the ankle dorsiflexion range of motion measure obtained from the new version of the WBLT. A total of 50 active adults completed this study. All participants performed the new version of the WBLT on three different occasions, with a two-week interval between testing sessions. Reliability was examined through the change in the mean between consecutive pairs of testing sessions (ChM), standard error of measurement (SEM), minimal detectable change at 95% confidence interval (MDC95), and intraclass correlation coefficient (ICC2,k). The findings showed negligible or trivial ChM values for all the flexibility measures analysed (<1°). Furthermore, the SEM and MDC95 scores for the ankle dorsiflexion measure were 1.3 and 3.8 respectively, and the ICC2k was 0.95. Therefore, this study demonstrated that the ankle dorsiflexion measure obtained from the new version of the WBLT has excellent test-retest reliability scores. Thus, an observed change larger than 3.8° from baseline scores after performing a treatment would indicate that a real change in ankle dorsiflexion range of motion was likely.

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

Abstract The main purposes of this study were to (a) investigate acute effects of static and dynamic lower limb stretching routines on total response time, pre-motor time and motor time of the medial and lateral hamstrings during maximal eccentric isokinetic knee flexion; and (b) determine whether static and dynamic routines elicit similar responses. A total of 38 active adults completed the following intervention protocols in a randomised order on separate days: (a) non-stretching (control condition), (b) static stretching and (c) dynamic stretching. After the stretching or control intervention, total response time, pre-motor time and motor time of the medial and lateral hamstrings were assessed during eccentric knee flexion movements with participants prone. Measures were compared via a mixed-design factorial ANOVA. There were no main effects for total response time, pre-motor time and motor time. The results suggest that dynamic and static stretching has no influence on hamstrings response times (total response time, pre-motor time and motor time) and hence neither form of stretching reduces this primary risk factor for anterior cruciate ligament injury.

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.

El entrenamiento de la flexibilidad: técnicas de estiramiento

Palabras clave: Estiramiento estatico. Estiramiento dinamico. Estiramiento balistico. Facilitacion neuromuscular propioceptiva. Rutinas de estiramiento. Rango de movimiento. RESUMEN La realizacion sistematizada de rutinas de estiramiento es una practica muy comun en el ambito clinico y fisico-deportivo con el proposito principal de mantener o mejorar la amplitud de movimiento de una articulacion o conjunto de articulaciones. Ademas, los estiramientos parecen ser un medio muy indicado para el cuidado, la prevencion y el mantenimiento de las capacidades fisicas de cada individuo o para su desarrollo.

Inter-session reliability and sex-related differences in hamstrings total reaction time, pre-motor time and motor time during eccentric isokinetic contractions in recreational athlete

The purposes were twofold: (a) to ascertain the inter-session reliability of hamstrings total reaction time, pre-motor time and motor time; and (b) to examine sex-related differences in the hamstrings reaction times profile. Twenty-four men and 24 women completed the study. Biceps femoris and semitendinosus total reaction time, pre-motor time and motor time measured during eccentric isokinetic contractions were recorded on three different occasions. Inter-session reliability was examined through typical percentage error (CVTE), percentage change in the mean (CM) and intraclass correlations (ICC). For both biceps femoris and semitendinosus, total reaction time, pre-motor time and motor time measures demonstrated moderate inter-session reliability (CVTE<10%; CM<3%; ICC>0.7). The results also indicated that, although not statistically significant, women reported consistently longer hamstrings total reaction time (23.5ms), pre-motor time (12.7ms) and motor time (7.5ms) values than men. Therefore, an observed change larger than 5%, 9% and 8% for total reaction time, pre-motor time and motor time respectively from baseline scores after performing a training program would indicate that a real change was likely. Furthermore, while not statistically significant, sex differences were noted in the hamstrings reaction time profile which may play a role in the greater incidence of ACL injuries in women.