Is hamstrings-to-quadriceps torque ratio useful for predicting anterior cruciate ligament and hamstring injuries? A systematic and critical review

Hamstrings-quadriceps strength ratio could be related to falls in community-living older adults

A prior study reported that the concentric strength imbalance between hamstrings and quadriceps is associated with falls in older adults. Given that the concentric strength may not be measured as conveniently as the isometric strength, it is meaningful to test whether the isometric hamstring-quadricep strength imbalance is related to falls among older adults. This study sought to explore whether the hamstrings-quadriceps ratio could differentiate fallers from non-fallers in community-dwelling older adults. One hundred and eleven older adults were included in this cross-sectional study. Their isometric knee joint strength capacity (extensors and flexors) was measured. Based on their fall history in the past year, they were classified as fallers (at least one fall) or non-fallers (no fall). The hamstrings-quadriceps ratio was compared between the faller and non-faller groups. The receiver operating characteristic analysis was used to determine the cutoff value of the hamstrings-quadriceps ratio able to best classify fallers and non-fallers. Fallers showed a significantly lower hamstrings-quadriceps ratio than non-fallers (p = 0.008). The receiver operating characteristic analysis identified 0.733 as the best ratio to differentiate fallers from non-fallers with an accuracy of 64.0 %. A 0.1-unit reduction in the hamstrings-quadriceps ratio increases the probability of falling by a factor of 1.30. The hamstrings-quadriceps ratio could be used as an additional fall risk factor when assessing the risk of falls among older adults. A smaller than 0.733 hamstring-quadriceps ratio may indicate a high risk of falls.

Prediction of specific structural damage to the knee joint using qualitative isokinetic analysis

BACKGROUND

An isokinetic moment curve (IMC) pattern-damaged structure prediction model may be of considerable value in assisting the diagnosis of knee injuries in clinical scenarios. This study aimed to explore the association between irregular IMC patterns and specific structural damages in the knee, including anterior cruciate ligament (ACL) rupture, meniscus (MS) injury, and patellofemoral joint (PFJ) lesions, and to develop an IMC pattern-damaged structure prediction model.

METHODS

A total of 94 subjects were enrolled in this study and underwent isokinetic testing of the knee joint (5 consecutive flexion-extension movements within the range of motion of 90°-10°, 60°/s). Qualitative analysis of the IMCs for all subjects was completed by two blinded examiners. A multinomial logistic regression analysis was used to investigate whether a specific abnormal curve pattern was associated with specific knee structural injuries and to test the predictive effectiveness of IMC patterns for specific structural damage in the knee.

RESULTS

The results of the multinomial logistic regression revealed a significant association between the irregular IMC patterns of the knee extensors and specific structural damages ("Valley" - ACL, PFJ, and ACL + MS, "Drop" - ACL, and ACL + MS, "Shaking" - ACL, MS, PFJ, and ACL + MS). The accuracy and Macro-averaged F1 score of the predicting model were 56.1% and 0.426, respectively.

CONCLUSION

The associations between irregular IMC patterns and specific knee structural injuries were identified. However, the accuracy and Macro-averaged F1 score of the established predictive model indicated its relatively low predictive efficacy. For the development of a more accurate predictive model, it may be essential to incorporate angle-specific and/or speed-specific analyses of qualitative and quantitative data in isokinetic testing. Furthermore, the utilization of artificial intelligence image recognition technology may prove beneficial for analyzing large datasets in the future.

Does Pelvic Tilt Angle Influence the Isokinetic Strength of the Hip and Knee Flexors and Extensors?

The purpose of this study was to examine the effect of pelvic tilt angle on maximum hip and knee muscles' strength and antagonist/agonist strength ratios. Twenty-one young males and females performed maximum isokinetic concentric knee extension-flexion and hip extension-flexion efforts at 60°·s-1, 120°·s-1, and 180°·s-1 from three positions: anterior, neutral, and posterior pelvic tilt. Peak torques and knee flexor-to-extensor and hip flexor-to-extensor torque ratios were analyzed. An analysis of variance showed that peak hip extensor torque was significantly greater in the anterior pelvic tilt condition compared to either neutral or posterior pelvic tilt angles (p > 0.05). No effects of changing pelvic tilt angle on hip flexor, knee flexor, or knee extension values were found (p > 0.05). The hip flexor-to-extensor torque ratio decreased (p < 0.05) in the anterior pelvic tilt position relative to the other positions, while no difference in the knee flexor-to-extensor ratio between pelvic positions was observed (p > 0.05). This study shows that an increased anterior pelvic tilt affects the maximum isokinetic strength of the hip extensors, supporting previous suggestions regarding the link between pelvic position and hip and knee muscle function. Isokinetic testing from an anterior pelvic tilt position may alter the evaluation of hip flexion/extension strength.

Evaluation of Strength and Functional Ability of Soccer Players Two Years After Anterior Cruciate Ligament Reconstruction: A Cross-sectional Study

OBJECTIVES

This study examines the strength and functional capacity of active soccer players two years post anterior cruciate ligament reconstruction (ACLR).

METHODS

Sixteen players, two years post ACLR, participated. Isokinetic tests assessed Peak Torque (PT) for concentric and eccentric contractions, along with conventional (H/Qconv) and functional (H/Qfunc) H/Q ratios at various angular velocities. Functional ability was gauged through hop tests. Paired-Samples T Test compared PT and hop test values, as well as H/Qconv and H/Qfunc ratios between involved and non-involved limbs. Limb symmetry was evaluated using the Limb Symmetry Index (LSI).

RESULTS

After two years, participants exhibited significant differences in concentric PT between limbs. The non-involved limb demonstrated superior performance at isokinetic speeds. Eccentrically, PT for knee extensors and flexors showed no significant disparities between the operated and non-operated limbs across all velocities tested. Most participants did not achieve LSI 90-110% for knee extensors and flexors. No noteworthy distinctions were observed in H/Qconv, H/Qfunc, and hop tests between limbs. The majority met LSI 90-110% in hop tests, except in the 30-second side hop (37%).

CONCLUSIONS

Two years post ACLR, soccer players still manifest strength and functional deficits, heightening the risk of injury.

Higher Eccentric Hamstring Muscle Fatigue After Participation in a Soccer Match in Young Female Athletes

BACKGROUND

Hamstring (HS) strength deficits and imbalances have been identified as risk factors for sustaining anterior cruciate ligament (ACL) injuries and muscular strains, with HS injuries being the most prevalent muscle injuries in soccer athletes. The aim of this study was to investigate HS eccentric strength before and after a soccer match in both male and female soccer athletes.

HYPOTHESIS

Soccer athletes have changes in eccentric HS strength after a soccer game.

STUDY DESIGN

Cohort observational study.

LEVEL OF EVIDENCE

Level 3.

METHODS

HS eccentric strength (mean and absolute peak torque and total work) was measured in 64 healthy male and female competitive football athletes (14-25 years) with an automatic device during the execution of the Nordic hamstring exercise (NHE) test before and after a 90-minute soccer match. The anterior-knee laxity (AKL) was quantified with an arthrometer.

RESULTS

Mean and absolute eccentric HS peak torque decreased by 24.5 N.m (-12.34%; P < 0.01) and 21.9 N.m (-10.08%; P < 0.01) in female athletes, whereas their male peers improved by 19.9 N.m (+9.01%; P = 0.01) and by 20.9 N.m (+8.51%; P = 0.02), respectively. HS total work in female athletes decreased by 831.1 J (P < 0.01) compared with the male athlete reduction of 235.3 J. Both the pre- versus postmatch intersex mean and absolute eccentric HS peak torque changes were significant (P < 0.01), as were the changes in HS total work (P < 0.01). The pre- versus postmatch AKL difference and the dominant versus nondominant limb comparison of the strength parameters were not significantly different. Younger female athletes (14-19 years old) presented a greater decrease in mean and absolute peak HS eccentric strength compared with those in older female athletes and men.

CONCLUSION

HS eccentric strength and work differ based on athlete sex, as measured by the NHE test. Mean peak, absolute peak, and total work showed greater reductions in female athletes than those in their male peers. The subgroup of 14- to 19-year-old female athletes experienced the highest reduction in strength parameters.

Biomechanical Factors Predisposing to Knee Injuries in Junior Female Basketball Players

This cross-sectional observational study aims to determine isokinetic normality data at different speeds, and isometric data of ankle and knee joints, in healthy basketball players aged 15-16 years old. The participants were recruited through non-probabilistic convenience sampling. Sociodemographic, anthropometric, and biomechanical variables were collected. The study involved 42 participants. Right-leg dominance was higher in women (85.7%) than in men (78.6%). Men had a higher weight, height, and body mass index compared to women. Statistically significant differences were observed between sex and height (p < 0.001). Significant differences were found between sexes in knee flexor and extensor strength at different isokinetic speeds (30°, 120°, and 180°/s), except for the maximum peak strength knee flexion at 180°/s in the right leg. In the ankle, the variables inversion, eversion, and work strength values at different isokinetic speeds and full RoM, by sex, were not significantly different, except for the right (p = 0.004) and the left (p = 0.035) ankle full RoM. The study found lower knee extensor strength in women, indicating the need to improve knee flexor/extensor strength in women to match that of men, as seen in other joints. The results can guide the development of preventive and therapeutic interventions for lower limb injuries in basketball players.

Testing the Posterior Chain: Diagnostic Accuracy of the Bunkie Test versus the Isokinetic Hamstrings/Quadriceps Measurement in Patients with Self-Reported Knee Pain and Healthy Controls

(1) Background: The isokinetic measurement (IM) of the leg muscles is well established but costly, whereas the Bunkie Test (BT) is a rarely investigated but easy-to-conduct functional test to evaluate the total posterior chain. Although the tests differ in aim and test structures, both have their justification in the assessment process. Therefore, this study evaluated the diagnostic accuracy of the BT and the IM. (2) Methods: 21 participants (9 female, 12 male; age, 26.2 ± 5.26 years; weight 73.8 ± 14.6 kg; height 176.0 ± 9.91 cm) and 21 patients (9 female, 12 male; age, 26.5 ± 5.56 years; weight, 72.6 ± 16.9 kg; height 177.0 ± 10.1 cm) with self-reported pain in the knee performed the IM and the BT. For IM, we calculated the ratio of the knee mean flexor/extensor peak torque (H/Q ratio) for 60°/s and 120°/s, and BT performance was measured in seconds. We classified the IM (<0.6 H/Q ratio) and the BT (leg difference ≥4 s) as binary results according to the literature. We calculated the sensitivity and specificity, which we compared with the Chi-Square test, and the 95% confidence intervals (CI). A p-value of ≤0.05 is considered significant. (3) Results: The sensitivity for the BT was 0.89, 95% CI [0.67, 0.99], and the specificity was 0.52 [0.30, 0.74]. For the IM, the sensitivity was 0.14 [0.03, 0.36] for 60°/s and 0.05 [0.00, 0.24] for 120°/s, and the specificity was 0.70 [0.46, 0.88] for 60°/s and 0.90 [0.68, 0.99] for 120°/s. The results of the Chi-Square tests were significant for the BT (χ2 (1) = 6.17, p = 0.01) but not for the IM (60°/s: χ2 (1) = 0.70, p = 0.40; 120°/s: χ2 (1) = 0.00, p = 0.97). (4) Conclusions: Patients were more likely to obtain a positive test result for the BT but not for the IM.

No Association Between Hamstrings-to-Quadriceps Strength Ratio and Second ACL Injuries After Accounting for Prognostic Factors: A Cohort Study of 574 Patients After ACL-Reconstruction

BACKGROUND

The stress on the anterior cruciate ligament (ACL) induced by the quadriceps can be attenuated by activation of the hamstrings by exerting an opposing torque to the anterior translation of tibia. Consequently, considering the ratio between strength of the hamstrings-to-quadriceps (HQ-ratio) may be of value to reduce the odds of second ACL injuries. The objective was therefore to evaluate (1) the association between HQ-ratio and the occurrence of a second ACL injury in patients after ACL-reconstruction within 2 years of return to preinjury sport level and (2) to compare the HQ-ratio between males and females after ACL reconstruction.

METHODS

Patients who had undergone primary ACL reconstruction and participated in knee-strenuous activity preinjury were included. Demographics, the occurrence of a second ACL injury, and muscle strength test results before returning to preinjury sport level were extracted from a rehabilitation registry. The endpoint was set at a second ACL injury or 2 years after return to preinjury sport level. A multivariable logistic regression was used to analyze the association between the HQ-ratio and a second ACL injury.

RESULTS

A total of 574 patients (50.0% female) with a mean age of 24.0 ± 9.4 years at primary ACL reconstruction were included. In the univariable logistic regression analysis, the odds of sustaining a second ACL injury decreased by 3% for every 1% increase in the HQ-ratio (OR 0.97 [95% CI 0.95-1.00], p = 0.025). After adjusting for the time from reconstruction to return to preinjury sport level, sex, preinjury sport level, graft choice, age, and body mass index, the results were no longer significant (OR 0.98 [95% CI 0.95-1.01], p = 0.16). Females had a higher HQ-ratio compared with males for both the ACL-reconstructed and uninjured side (3.7% [95% CI 5.7; 1.8%], p = 0.0002 and 3.3% [95% CI 4.6; 2.1], p < 0.001, respectively).

CONCLUSION

The HQ-ratio did not significantly affect the odds for sustaining a second ACL injury upon return to preinjury sports level after primary ACL reconstruction. Females had a significant higher HQ-ratio than males for both the ACL reconstructed and uninjured side.

Lower hamstring to quadriceps muscle strength ratio and lower body weight as factors associated with noncontact anterior cruciate ligament injury in male American football players: A prospective cohort study

Background

Previous studies have aimed to determine the use of certain risk factors in predicting the occurrence of noncontact anterior cruciate ligament (ACL) injuries. Unfortunately, evidence regarding noncontact ACL injuries in male American football players is limited. This prospective cohort study aimed to identify intrinsic risk factors for noncontact ACL injury among male American football players.

Methods

This study evaluated 152 male American football players in Japan for potential noncontact ACL injury risk factors during a preseason medical assessment, including anthropometric, joint laxity, and flexibility, muscle flexibility, muscle strength, and balance measurements. A total of 25 variables were examined. Participants were monitored during each season for noncontact ACL injury, as diagnosed by physicians.

Results

Noncontact ACL injuries occurred in 11 knees of 11 players (prevalence; 7.1 %). Injured players were significantly more likely to have lightweight (P = 0.049). No statistically significant between-group differences were found for any other variables. Participants with a lower hamstring to quadriceps (H/Q) ratio (P = 0.04) were more likely to sustain noncontact ACL injuries.

Conclusion

Lower H/Q ratio and lower body weight were significantly associated with new-onset noncontact ACL injury in male American football players. These findings will help develop strategies to prevent noncontact ACL injuries in male American football players.

Discrete Hamstring: Quadriceps Strength Ratios Do Not Represent Angle-Specific Ratios in Premier League Soccer Players

ABSTRACT

Lunn, DE, Nicholson, G, Cooke, M, Crespo, R, Robinson, T, Price, RJ, and Walker, J. Discrete hamstring: quadriceps strength ratios do not represent angle-specific ratios in Premier League soccer players. J Strength Cond Res 37(12): 2417-2422, 2023-This study compared angle-specific hamstring:quadriceps (H:Q) ratios with their discrete counterparts during strength testing in professional male soccer players. Twenty-seven professional English Premier League soccer players were recruited for this study (age: 22 ± 4 years; stature: 1.81 ± 0.08 m; body mass: 74.7 ± 6.5 kg). Isokinetic testing of the knee flexors and extensors was conducted concentrically at two angular velocities (60° and 240°·s -1 ) and eccentrically (for the knee flexors only) at 30°·s -1 . Conventional H:Q ratio was calculated as the ratio between peak joint moment in the flexors and extensors at 60°·s -1 . Functional H:Q ratio was calculated as the peak joint moment in the flexors during the eccentric condition and the extensors at 240°·s -1 . Discrete conventional and functional H:Q ratios were 0.56 ± 0.06 and 1.28 ± 0.22, respectively. The residual differences between discrete values and angle-specific residual values were 13.60 ± 6.56% when normalized to the magnitude of the discrete value. For the functional ratios, the normalized residual was 21.72 ± 5.61%. Therefore, neither discrete ratio was representative of angle-specific ratios, although the conventional ratio had lower error overall. Therefore, practitioners should consider H:Q ratio throughout the full isokinetic range of motion, not just the discrete ratio calculated from peak joint moments, when designing and implementing training programs or monitoring injury risk, recovery from injury, and readiness to return to play.

Neuromuscular Response during Different Side-Cutting Maneuvers and Its Influence on the Risk of Knee Injuries

BACKGROUND

The objective of this study was to investigate the impact of a customized exercise program on electromyographic (EMG) variables during side-cutting maneuvers.

METHODS

Fifty-seven physically active volunteers were recruited and randomized into two groups: a control group (CG) and an experimental group (EG). The CG maintained their regular physical activity, while the EG followed an individualized, integrated exercise regimen that included strength, neuromuscular, proprioceptive, eccentric training, and whole-body vibration (WBV) exercises, lasting for 12 weeks. EMG-Root Means Square (RMS) values for the quadriceps (Q) and hamstrings (H) were measured immediately following initial foot contact at 50, 100, 150, and 200 milliseconds. Changes in EMG activity were evaluated before and after a twelve-week intervention, and the effect size (ES, 90% confidence limit [90%CL]) was calculated.

RESULTS

The results showed that the EG participants exhibited enhanced co-contraction as measured by the hamstring/quadriceps ratio (H/Q ratio) during both open and cross-cutting side maneuvers after the twelve-week intervention.

CONCLUSION

Furthermore, the customized, integrated exercise program that combined strength, neuromuscular, proprioceptive, eccentric training, and WBV exercises were could potentially serve as a beneficial neuromuscular and biomechanical strategy for addressing knee injury risk in non-professional, physically active populations at high risk for such injuries.

The bone mineral density and isokinetic knee strength in amputee soccer players

OBJECTIVE

The aim of this study was to examine the isokinetic knee strength, H/Q ratio (%), and bone mineral density values between amputees (n=14; amputee soccer players) and healthy football players (n=14; non-amputee soccer players).

METHODS

A total of 28 amputee soccer players and non-amputee soccer players participated in the study. An isokinetic dynamometer was used to determine the knee flexion/extension forces of the dominant legs of the athletes at 60, 180, and 240°/s. Bone mineral density scans were performed using dual-energy X-ray absorptiometry.

RESULTS

H/Q ratio and 60º/s flexion and 180 and 240º/s flexion/extension strength (p<0.05) were found to be high (180º/s, p=0.03; 240º/s, p=0.048) in the non-amputee soccer player group. Accordingly, the bone mineral density values of the lumbar vertebra, femoral neck, proximal metaphysis of the femur (p<0.01), tibia/fibula proximal metaphysis, and tibia/fibula distal metaphysis (p<0.05) were found to be high. A correlation was observed between the 60º/s knee extension strength and tibia/fibula diaphyseal bone mineral density (p=0.025; r=0.594) and tibia/fibula distal metaphysis bone mineral density (p=0.017; r=0.623) values in the amputee soccer players group. The Z-scores of the amputee soccer players and non-amputee soccer players were in the expected range according to age (>-2).

CONCLUSION

The bone mineral density, H/Q ratio, and all measured angular velocities of isokinetic strength were high in non-amputee soccer players. This finding made us think that lower extremity amputation may also be associated with losing strength. However, it was observed that the relationship between strength and bone mineral density in amputee athletes might vary according to different angular velocities. It is recommended that isokinetic strength measurement can be evaluated together with bone mineral density in athletes.

Regulation of Bone by Mechanical Loading, Sex Hormones, and Nerves: Integration of Such Regulatory Complexity and Implications for Bone Loss during Space Flight and Post-Menopausal Osteoporosis

During evolution, the development of bone was critical for many species to thrive and function in the boundary conditions of Earth. Furthermore, bone also became a storehouse for calcium that could be mobilized for reproductive purposes in mammals and other species. The critical nature of bone for both function and reproductive needs during evolution in the context of the boundary conditions of Earth has led to complex regulatory mechanisms that require integration for optimization of this tissue across the lifespan. Three important regulatory variables include mechanical loading, sex hormones, and innervation/neuroregulation. The importance of mechanical loading has been the target of much research as bone appears to subscribe to the "use it or lose it" paradigm. Furthermore, because of the importance of post-menopausal osteoporosis in the risk for fractures and loss of function, this aspect of bone regulation has also focused research on sex differences in bone regulation. The advent of space flight and exposure to microgravity has also led to renewed interest in this unique environment, which could not have been anticipated by evolution, to expose new insights into bone regulation. Finally, a body of evidence has also emerged indicating that the neuroregulation of bone is also central to maintaining function. However, there is still more that is needed to understand regarding how such variables are integrated across the lifespan to maintain function, particularly in a species that walks upright. This review will attempt to discuss these regulatory elements for bone integrity and propose how further study is needed to delineate the details to better understand how to improve treatments for those at risk for loss of bone integrity, such as in the post-menopausal state or during prolonged space flight.

Low Pre-Season Hamstring-to-Quadriceps Strength Ratio Identified in Players Who Further Sustained In-Season Hamstring Strain Injuries: A Retrospective Study from a Brazilian Serie A Team

A common pre-season injury prevention assessment conducted by professional football clubs is the hamstring-to-quadriceps (H:Q) strength ratio calculated by peak torque (PT). However, it is debatable whether players that present low pre-season H:Q ratios are more susceptible to further sustaining in-season hamstring strain injuries (HSI). Based upon retrospective data from a Brazilian Serie A football squad, a particular season came to our attention as ten out of seventeen (~59%) professional male football players sustained HSI. Therefore, we examined the pre-season H:Q ratios of these players. H:Q conventional (CR) and functional (FR) ratios, and the respective knee extensor/flexor PT from the limbs of players further sustaining in-season HSI (injured players, IP) were compared to the proportional number of dominant/non-dominant limbs from uninjured players (UP) in the squad. FR and CR were ~18-22% lower (p < 0.01), whereas quadriceps concentric PT was ~25% greater for IP than UP (p = 0.002). Low scores of FR and CR were correlated (p < 0.01) with high levels of quadriceps concentric PT (r = -0.66 to -0.77). In conclusion, players who sustained in-season HSI had lower pre-season FR and CR compared to UP, which appears to be associated with higher levels of quadriceps concentric torque than hamstring concentric or eccentric torque.

Evidence for isokinetic and functional testing in return to sport decisions following ACL surgery

The rupture and reconstruction of the anterior cruciate ligament (ACL) of the knee are associated with an increased risk of functional instability, a reduction in sports performance, and a higher risk of future additional injuries. Competitive athletes who participate in sports that require pivoting, cutting, and jumping are at particularly high risk for ACL rupture. The return to sport progression continuum after surgery includes sports-specific rehabilitation, evaluation of strength and function, gradual participation in exercise training with progressively challenging activities in the field of play, participation in sports at a lower level, and finally a return to preinjury-level sports competition. This narrative review evaluates the evidence that supports the use of quadriceps and hamstrings isokinetic strength testing and sports-specific functional skills assessments to evaluate progress with rehabilitation after ACL surgery. Strength evaluations, hop tests, agility tests, and the limb symmetry index are described, as well as the associations of quadriceps and hamstrings muscle strength and functional test results with successful return to sports and the risk of ACL graft rupture and contralateral knee injuries. Suggestions for future research directions are presented including the importance of presurgery testing, standardization of test batteries, and comparison of test results with normative data.