A New Measuring Approach in Assessing Hamstring Flexibility: Reliability, Validity, and Applicability of Isolated Hamstring Flexibility Test

OBJECTIVE

This study was planned to determine the reliability, validity, and applicability of the isolated hamstring flexibility test (IHFT).

DESIGN

A cohort study (diagnosis); level of evidence, 2.

SETTING

It was performed in the research and application laboratory.

PARTICIPANTS

Seventy-five individuals aged 18 to 25 years, selected through simple probability random sampling, with a normal Beighton Horan and Joint Mobility Index scores, and who volunteered to participate, were included for evaluation.

INTERVENTIONS

On then first and third days, participants underwent muscle strength, sit-and-reach test, active knee extension test, IHFT for validity and reliability. Stretching exercises were prescribed as a home program for 31 patients with limited knee extension, and measurements were repeated at the end of the eighth week.

MAIN OUTCOME MEASURES

Sit-and-reach test, active knee extension test, IHFT.

RESULTS

The test-retest reliability was high (intraclass correlation coefficient, 0.993). Our test demonstrated validity when compared in terms of flexibility gained. A significant difference was found between pre-post stretching exercise training in all 3 tests (P < 0.05).

CONCLUSION

It was observed that the IHFT is reliable and applicable in determining hamstring flexibility. Given the absence of another test specifically measuring hamstring flexibility in isolation, its indirect validity was established through analysis with other tests using the gold standard for assessing gains in hamstring flexibility.

Do participants in a physical activity program from a Care Sport Connector become healthier? An explorative study from the Netherlands

INTRODUCTION

Care Sport Connectors (CSCs) have been appointed to create a connection between the primary care and physical activity (PA) sectors to stimulate residents who are inactive to become more physically active to gain health benefits. The objective of this explorative study was to find out whether CSCs achieve these goals by testing the hypothesis that more residents become physically active, and score higher for health-related fitness and health-related quality of life.

METHOD

We conducted a longitudinal study design whereby participants (n = 402) were measured at three time points: at the start of their PA program (T0); after 6 months (T1); and after 1 year (T2). Participants conducted a fitness test to measure their health-related physical fitness and filled in questionnaires to assess PA level (PA-, Fit-, Combi-, and sport norm), health-related quality of life, motivation for PA, and personal information. We used a multi-level analysis to test whether outcomes of participants differ over time. Participants who dropped out and maintainers were compared with a chi-square test and a one-way ANOVA.

RESULTS

This study showed that one-third of the participants dropped out (n = 139). Participants who dropped out were, compared with maintainers, less physically active (P = 0.004) and were more often reached in bigger municipalities, by an integral approach. More participants meet the PA norm (P = 0.007) and sport norm (P<0.001) at T2 then at T0. Scores in health-related physical fitness and quality of life were significant but not a meaningful gain in health-related fitness.

CONCLUSION

More residents become physically active and participate in sport because they took part in a PA programs or activity organized by a CSC. Lifestyle interventions should be offered with a higher frequency, intensity, and focus on behavior change. It is necessary to invest in combined lifestyle interventions offered by a collaboration of primary care, welfare, and PA professionals.

Relationship between muscular extensibility, strength and stability and the transmission of impacts during fatigued running

The aim was to analyse the relationship between isokinetic strength, dynamic stability, muscular extensibility and impacts transmission during fatigued running. Low- and high-frequency impacts-related to body movements and the severity of impacts, respectively-were assessed in 17 male recreational runners, before and after a treadmill running fatigue protocol, using a triaxial accelerometry system. High-frequency impacts in the tibia were negatively correlated to the knee angle at which the quadriceps peak torque was reached (p = 0.014), and also to the extensibility of the hamstrings and soleus (p = 0.001 and p = 0.023, respectively). The increases of high-frequency impacts in tibia caused by fatigue were positively related to the knee angle at which the hamstrings peak torque was reached (p = 0.001) and to stability after landing (p = 0.007). The attenuation of high-frequency impacts was positively related to hamstrings/quadriceps ratio of strength (p = 0.010) and to stability (p = 0.006). Limiting possible deficits in hamstring and soleus range of motion, improving stability after landing, developing hamstring and quadriceps strength in elongated muscle range, and maintaining a balanced ratio of hamstring/quadriceps strength could help to reduce the injury risk in running.

Medical ozone on hamstring injury in a professional athlete assessed by thermography: a clinical case report

Injuries associated with the hamstring muscles in the running athlete are increasingly investigated due to the economic and functional consequences associated with them. Although hardly used in the treatment of sports injuries, medical ozone is effective and very well tolerated in the treatment of musculoskeletal pain, it was decided to add a series of medical ozone infiltrations to the treatment. The evolution of the case was recorded by medical thermography, in addition to measuring pain intensity (visual analog scale) and functional capacity (toe touch test). Pain intensity (visual analog scale) decreased from seven at baseline to two at the end of treatment (after two ozone infiltrations, one weekly). Mobility of the damaged area (toe touch test) improved from a distance of 8 cm at baseline to 0 cm at the end of treatment. Regarding medical thermography, after the first and second infiltration of ozone, the temperature rose to a significant increase in perfusion from baseline from 31.2 to 31.8 °C and from 31.2 to 32 °C, respectively. These results suggest the possible interest of medical ozone as an adjuvant treatment for the recovery of sports tendinopathies and encourage us to carry out further studies.

Effects of proprioceptive neuromuscular facilitation stretching at low-intensities with standing toe touch on developing and maintaining hamstring flexibility

BACKGROUND

Proprioceptive neuromuscular facilitation (PNF) stretching at low intensities has been rarely investigated. Previous studies have shown that hamstring flexibility after stretching is only temporary.

OBJECTIVE

The aim of this study was to assess the effect of low intensities (40% and 10% of maximum voluntary isometric contraction, MVIC) of PNF stretching on hamstring muscles and to assess the effect of standing toe touch on the duration of hamstring flexibility.

METHODS

This was a single-blind randomized controlled trial. Sixty-four healthy adults (age, 22.67 ± 1.73 years) were selected and divided into four groups: 40% intensity PNF stretching (P40), 10% intensity PNF stretching (P10), 40% intensity PNF stretching with toe touch (P40 with TT), and 10% intensity PNF stretching with toe touch (P10 with TT). Hamstring flexibility was measured using the active knee extension test (pre-stretching, post-stretching, and 3, 6, 9, 12, and 15 min after PNF stretching).

RESULTS

In the P40, P40 with TT, and P10 with TT groups, significant changes were observed at all time points after stretching (p < 0.05). In the P10 group, significant changes were only observed immediately post stretching (p = 0.006) and at 3 min (p = 0.029) after stretching. In terms of maintaining the duration of flexibility, the P40 with TT and P10 with TT groups were superior to the P40 and P10 groups.

CONCLUSION

PNF stretching at low intensity, approaching 40% of MVIC, led to more flexibility than 10% MVIC. Additionally, standing toe touch after PNF stretching is recommended to develop and maintain hamstring flexibility.

Flexibility Measurement Affecting the Reduction Pattern of Back Muscle Activation during Trunk Flexion

Numerous studies have been conducted on lower back injury caused by deeper stooped posture, which is associated with the back muscle flexion–relaxation phenomenon (FRP). Individual flexibility also affects FRP; individuals with high flexibility have the benefit of delayed FRP occurrence. This study attempted to determine the most efficient measurement of flexibility for evaluating the occurrence and degree of FRP when participants flexed their trunk forward. We recruited 40 male university students who were grouped on the basis of three flexibility measurements (toe-touch test, TTT; sit-and-reach test, SRT; modified Schober’s test, MST) into three levels (high, middle and low). Muscle activation (thoracic and lumbar erector spinae, TES and LES, respectively; hamstring, HMS) and lumbosacral angle (LSA) were recorded when the trunk flexed forward from 0° (upright) to 15°, 30°, 45°, 60°, 75° and 90°. The results indicated that trunk angle had a significant effect on three muscle activation levels and LSA. The effects of muscles and LSA varied depending on flexibility measurement. TTT significantly discriminated LES electromyography findings between high and low flexibility groups, whereas MST and SRT distinguished between high and non-high flexibility groups. The TTT values positively correlated with the time of LES FRP occurrence, showing that the higher the TTT, the slower the occurrence of FRP. This is beneficial in delaying or avoiding excessive loading on the passive tissue of the lumbar spine when performing a deeper trunk flexion.

Pre-stretching of the Hamstrings Before Squatting Acutely Increases Biceps Femoris Thickness Without Impairing Exercise Performance

Background: Bilateral squat exercise is widely used in resistance training (RT) programs to increase lower limb strength and muscle mass, but this exercise does not result in significant hypertrophy of the hamstrings. It has been speculated that stretching between sets with a certain degree of tension results in muscle hypertrophy, while acute stretching could decrease performance during maximal contractions.

Objective: This study investigated the acute effects of hamstring stretching before bilateral squatting on muscle thickness (MT), electromyography (EMG), and total training volume (TTV) on exercise performance.

Methods: Fourteen resistance-trained young men, with ∼7.5 years of RT experience, performed the 10 repetition maximum (RM) for the barbell squat in two sessions (test–retest) separated by period after 48 h. Participants engaged in two resistance exercise conditions separated by a 1 week recovery interval: one session employed hamstrings stretching and the other did not include hamstrings stretching. Before and after each resistance exercise session, the thickness of the quadriceps muscles and biceps femoris long head were obtained by ultrasound imaging. Moreover, the EMG amplitudes for the quadriceps muscles, biceps femoris, and iliocostalis muscles were recorded during back squat performance. The TTV was also evaluated for each exercise session.

Results: A significant increase in MT was observed after every set in both conditions for the evaluated quadriceps muscles (all p < 0.05), while for the biceps femoris, this effect was found only in the stretching condition (p < 0.05). EMG activity increased in the rectus femoris, vastus lateralis, and vastus medialis for the stretching condition. For the non-stretching condition, activity only increased in the vastus lateralis and medialis. There was no difference in EMG activity for the biceps femoris and iliocostalis in both conditions.

Conclusion: Stretching the hamstrings immediately before each set of the back squat can be used to acutely increase biceps femoris thickness without impairing squat performance.

Immediate and Short-Term Effects of Kinesio Taping Tightness in Mechanical Low Back Pain: A Randomized Controlled Trial

BACKGROUND

There is controversy regarding the best technique for applying Kinesio Taping (KT), and the theory supporting that skin convolutions may explain its efficacy has recently been challenged.

OBJECTIVE

To compare the immediate and short-term effectiveness of KT tightness on mechanosensitivity and spinal mobility in nonspecific low back pain (LBP), and to observe the influence of gender in the outcome measures.

DESIGN

Double-blind, randomized, controlled trial.

SETTING

University-based clinical research center.

PARTICIPANTS

A total of 75 individuals with a mean age of 33 years (±7.4 years), 60% female and 40% male, with nonspecific LBP were recruited and randomly assigned to 1 of the following study groups: standard KT tension (n = 26), increased KT tension (n = 25), and no KT tension (n = 24).

INTERVENTIONS

All participants received a two I-strip taping over the paravertebral muscles for 24 hours. Paper-off tension (15%-25% of the available stretch) was used in the standard KT group, which was increased to 40% in the increased KT tension group. The rest of participants received a taping procedure with no KT tension. Measurements were taken at baseline, immediately after the taping, 24 hours after the taping, and after KT removal.

MAIN OUTCOME MEASURES

The primary outcome included pressure pain thresholds over the erector spinae and gluteus medius muscles. The secondary outcome was lumbar mobility (assessed with a digital inclinometer, and back-saver sit-and-reach, finger-to-floor, and sit-and-reach tests).

RESULTS

In the between-groups analysis of the mean score changes after baseline assessment, no significant differences were found for any of the outcome measures (P > .05) except the left back-saver sit-and-reach test (P = .03). A statistically significant interaction group × gender × time was observed only for mechanosensitivity values (P = .02 for the gluteus and P = .01 for the erector spinae).

CONCLUSION

KT tightness does not seem to influence pain sensitivity and lumbar mobility in chronic LBP in either the immediate or short term.

LEVEL OF EVIDENCE

II.

Effects of Acute Fatigue of the Hip Flexor Muscles on Hamstring Muscle Extensibility

The purpose of the present study was to evaluate the influence of acute fatigue of the hip flexor muscles on scores attained in tests frequently used in literature to measure hamstring muscle extensibility, namely the passive straight leg raise (PSLR), active straight leg raise (ASLR), passive knee extension (PKE), active knee extension (AKE), sit-and-reach (SR) and toe-touch (TT) tests. A total of seventy-five healthy and recreationally active adults voluntarily participated in this study. To reach fatigue, the participants actively lifted their legs alternately as many times as possible. In the passive tests, the results were 7.10 ± 5.21° and 5.68 ± 4.54° higher (p < 0.01) for PSLR and PKE tests, respectively, after acute fatigue. However, in the ASLR test, the results were lower post-fatigue than pre-fatigue (mean difference = -5.30° ± 9.51°; p < 0.01). The AKE, SR and TT tests did not show significant differences between pre- and post-fatigue (p > 0.05). Moderate (r = 0.40) to high (r = 0.97) correlation coefficients were found, which were statistically significant among all the measured flexibility tests both pre- and post-fatigue. In conclusion, the active implication of the hip flexor muscles until reaching fatigue had acute influences on the results of the PSLR, PKE and ASLR tests, but not on the results of the AKE, SR and TT tests. It is recommended to use the AKE test to assess hamstring muscle extensibility in situations where athletes show fatigue in their hip flexor muscles.

Changes of general fitness and muscle properties following police cadet training

[Purpose] This study was performed to examine the relationship between physical performance and muscle properties during police cadet training. The study's hypothesis was that improved physical performance brought about by training, would in turn cause a reduction in muscle flexibility. [Subjects and Methods] Fifty-nine police cadets were included in this study. Standard fitness tests and quantitative assessments of muscular biomechanical properties were conducted before, during and after the 20-week cadet training. [Results] General fitness had improved at the end of the police cadet training. There was no significant decrease in muscle flexibility as measured by the Sit-and-Reach test. However, muscle compliance of the non-dominant leg measured by the relaxation coefficient had decreased at the end of the police cadet training. [Conclusion] The increased sit-and-reach distance could be due in part to strengthening of the abdominal muscles. On the other hand, the biomechanical test, which was specific to muscle extensibility, showed a reduction in the relaxation coefficient of the non-dominant leg. Our data suggests that changes in muscle compliance as a result of lower extremity training should be considered. This data may be useful in the design of a training protocol that prevents the potential injuries caused by reduced muscle flexibility.

The effects of interday rest on adaptation to 6 weeks of plyometric training in young soccer players

The purpose of this study was to determine the effects of short-term plyometric training interposed with 24 or 48 hours of rest between training sessions on explosive and endurance adaptations in young soccer players. A total of 166 players, between 10 and 17 years of age, were randomly divided into 3 groups: a control group (CG; n = 55) and 2 plyometric training groups with 24 hours (PT24; n = 54) and 48 hours (PT48; n = 57) of rest between training sessions. Before and after intervention, players were measured in squat jump, countermovement jump, 20 (RSI20) cm drop jump reactive strength index, broad long jump, 20-m sprint time, 10 × 5-m agility time, 20-m multistage shuttle run test, and sit-and-reach test. The plyometric training program was applied during 6 weeks, 2 sessions per week, with a load from 140 to 260 jumps per session, replacing some soccer-specific drills. After intervention, the CG did not show significant performance changes. PT24 and PT48 groups showed a small-to-moderate significant improvement in all performance tests (p < 0.001), with no differences between treatments. Although it has been recommended that plyometric drills should not be conducted on consecutive days, the study shows that plyometric training applied twice weekly on consecutive or nonconsecutive days results in similar explosive and endurance adaptations in young male soccer players.

Immediate Effects of Combining Local Techniques in the Craniomandibular Area and Hamstring Muscle Stretching in Subjects with Temporomandibular Disorders: A Randomized Controlled Study

OBJECTIVE

To assess the immediate effects on vertical mouth opening, orofacial mechanosensitivity, and lumbar and suboccipital mobility after adding a myofascial induction technique to a multimodal protocol in subjects with temporomandibular disorders (TMD).

DESIGN

A randomized and double-blind controlled trial was carried out.

SETTINGS/LOCATION

University-based physical therapy research clinic.

SUBJECTS

Sixty subjects (35±11.22 years) with TMD, and restricted mobility of the mandibular condyles and the first cervical vertebrae, were recruited and randomized to either a control group (CG) (n=30) or an experimental group (EG) (n=30).

INTERVENTIONS

The CG underwent a neuromuscular technique over the masseter muscles and passive hamstring muscle stretching. A suboccipital muscle inhibition technique was added to this protocol in the EG.

OUTCOME MEASURES

Primary measurements were made of vertical mouth opening and pressure pain threshold of the masseter muscles. Secondary outcome measures included pressure algometry of the trigeminal nerve, suboccipital range of motion, and lumbar spine mobility, assessed with the sit-and-reach (SAR) test and lumbar forward bending. All evaluations were collected at baseline and immediately after intervention.

RESULTS

In the intragroup comparison, the EG observed an increase in suboccipital flexion (p<0.001; F1,29=14.47; R(2)=0.33) and the SAR test (p=0.009; F1,29=7.89; R(2)=0.21). No significant differences were found in the between-group comparison for any variable (p>0.05).

CONCLUSION

The inclusion of a myofascial induction maneuver in a protocol combining local (neuromuscular treatment) and distal techniques (hamstring stretching) in subjects with TMD has no impact on improving mouth opening, suboccipital and lumbar mobility, and orofacial sensitivity to mechanical pressure.

Physical fitness factors to predict female Olympic wrestling performance and sex differences

To determine differences in anthropometric, body composition, physiological and neuromuscular markers between elite and amateur female wrestlers, 35 female wrestlers were assigned into 4 groups according to their body mass (light and middle weight) and their competitive level (elite and amateur): light weight (between 49 and 58 kg) in elite (n = 6) and amateur (n = 12) levels, and middle weight (between 58 and 67 kg) in elite (n = 7) and amateur (n = 10) levels. A binary logistic regression analysis was performed to identify which variables better predict female wrestling success. Elite female wrestlers were older (8-10%), had more training experience (27-29%), fat-free mass (3%), maximum strength in absolute and allometrically scaled values (13-33%), maximal muscle power (16-34%), mean and peak power during an arm crank Wingate testing in absolute and allometrically scaled values (17-23%), jumping height (2-9%) and grip (5-13%), and back isometric strength (10-13%) compared with amateur wrestlers (p < 0.05). When the results of the present research and those of a recent study performed in our laboratory with elite male wrestlers were compared, elite women presented lower (p < 0.05) maximum isometric and dynamic strength, muscle power output, and anaerobic metabolism values even when these data were normalized using allometric methods.

Accuracy and feasibility of video analysis for assessing hamstring flexibility and validity of the sit-and-reach test

The accuracy of video analysis of the passive straight-leg raise test (PSLR) and the validity of the sit-and-reach test (SR) were tested in 60 men and women. Computer software measured static hip-joint flexion accurately. High within-session reliability of the PSLR was demonstrated (R > .97). Test-retest (separate days) reliability for SR was high in men (R = .97) and women R = .98) moderate for PSLR in men (R = .79) and women (R = .89). SR validity (PSLR as criterion) was higher in women (Day 1, r = .69; Day 2, r = .81) than men (Day 1, r = .64; Day 2, r = .66). In conclusion, video analysis is accurate and feasible for assessing static joint angles, PSLR and SR tests are very reliable methods for assessing flexibility, and the SR validity for hamstring flexibility was found to be moderate in women and low in men.

Physical fitness factors to predict male Olympic wrestling performance

To determine differences in maximal strength and muscle power output of the arm and leg extensor muscles, peak and mean power during a modified standing crank-arm Wingate test, running speed, muscle extensibility, and anthropometric markers between elite and amateurs wrestlers according to the weight classes system; 92 male wrestlers were assigned into 6 groups according to their body mass (light, middle and heavy weight) and their competitive level (elite and amateur): Light Weight (body mass ranged between 55 and 68 kg) in elite (LW(E), n = 18) and amateur (LW(A), n = 15) level; Middle Weight (body mass ranged between 68 and 84 kg) in elite (MW(E), n = 18) and amateur (MW(A), n = 19) level; and Heavy Weight (body mass ranged between 84 and 100 kg) in elite (HW(E), n = 10) and amateur (HW(A), n = 12) level. Elite wrestlers were older (8-12%), had more training experience (25-37%), fat-free mass (3-5%), maximal strength in absolute and relative terms (8-25%), muscle power (14-30%), mean and peak power during crank-arm Wingate testing in absolute and relative terms (13-22%), jumping height (8-17%) as well as grip (6-19%) and back strength (7-20%) compared to amateur wrestlers. However, no differences were observed between elite and amateur groups in height, body mass index, percentage of body fat, hamstring extensibility and running speed. The present results suggest that the higher absolute and relative values of maximal strength, muscle power, and anaerobic metabolism, explained in part by the differences in lean mass and neural activation patterns, will give elite wrestlers a clear advantage during the most frequently used techniques in Olympic wrestling.