Hip Flexion Strength Research Articles

Risk factors for patellar tendinopathy in competitive volleyball players

BackgroundPatellar tendinopathy (PT) is an important problem in a volleyball population. However, in order to optimize rehabilitation and prevention strategies, not all intrinsic risk factors are known. This study is...

No Strength or Gait Benefit of Two-incision THA: A Brief Followup at 1 Year

Using comprehensive gait analysis and strength testing, we previously investigated the early (2-month) functional outcome after THA using two-incision and mini-posterior surgical approaches and found an advantage for the mini-posterior approach. Benefits included improved muscle strength, a less antalgic gait, and better hip function as reflected by changes in hip moments during level walking and stair climbing. We questioned how these differences in function would fare with longer followup. We determined whether the observed early functional advantages for the mini-posterior technique over the two-incision technique were still present 1 year postoperatively. We prospectively enrolled 22 patients with primary degenerative arthritis of the hip; of these, 21 completed gait and strength testing at 2 months, and 19 completed comprehensive gait and strength testing at 1 year (11 two-incision hips, eight mini-posterior hips). The 19 patients included 11 men and eight women with a mean age of 65 years (range, 40-85 years) and a mean (BMI) of 29 (range, 21-39). At 1 year postoperatively, the patients who had the mini-posterior THA had greater improvement in hip flexion strength and internal rotation strength, greater increase in hip flexor internal moment, and greater increase in single-leg stance time on level ground over the patients who had the two-incision THA. Compared with the two-incision approach, patients undergoing mini-posterior THA had persistently better function, including hip flexor and internal rotator muscle strength, hip flexor internal moment, and single-leg stance during level walking. Level II, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Heterogeneity in Rate of Decline in Grip, Hip, and Knee Strength and the Risk of All‐Cause Mortality: The Women's Health and Aging Study II

To assess the relationship between rate of change in muscle strength and all-cause mortality. Prospective observational study of the causes and course of physical disability. Twelve contiguous ZIP code areas in Baltimore, Maryland. Three hundred seven community-dwelling women aged 70 to 79 at study baseline. The outcome was all-cause mortality (1994-2009); predictors included up to seven repeated measurements of handgrip, knee extension, and hip flexion strength, with a median follow-up time of 10 years. Demographic factors, body mass index, smoking status, number of chronic diseases, depressive symptoms, physical activity, interleukin-6, and albumin were assessed at baseline and included as confounders. The associations between declining muscle strength and mortality were assessed using a joint longitudinal and survival model. Grip and hip strength declined an average of 1.10 and 1.31 kg/year between age 70 and 75 and 0.50 and 0.39 kg/year thereafter, respectively; knee strength declined at a constant rate of 0.57 kg/year. Faster rates of decline in grip and hip strength, but not knee strength, independently predicted mortality after accounting for baseline levels and potential confounders (hazard ratio (HR) = 1.33, 95% confidence interval (95% CI) = 1.06-1.67, HR = 1.14, 95% CI = 0.91-1.41, and 2.62, 95% CI = 1.43-4.78 for every 0.5 standard deviation increase in rate of decline in grip, knee, and hip strength, respectively). Monitoring the rate of decline in grip and hip flexion strength in addition to absolute levels may greatly improve the identification of women most at risk of dying.

Evaluation of Hip Flexion Strength Following Extreme Lateral Lumbar Interbody Fusion: Is the Psoas Muscle Seriously Injured?

Extreme Lateral Interbody Fusion (XLIF/DLIF) is one of the minimally invasive procedures that are designed to enable the surgeon to achieve both restoration of the degenerative disc height and a solid interbody fusion while minimizing the damage to the surrounding soft tissue. Although short term results have been promising, little data has been published to date regarding its risks and complication rate. Among the potential risks during XLIF are injuries to the psoas muscle, exiting ventral nerve root and to the genitofemoral nerve.

Age and Gender Differences in Hip Extension and Flexion Torque Steadiness

Background: Lower extremity torque steadiness has been shown to be an independent predictor of functional performance in older women. Hip muscle function is crucial for many types of activities of daily living, yet existing studies investigating torque steadiness for lower extremities are limited to assessing steadiness at the knee and ankle. Objective: The purpose of this study was to compare age and gender differences in hip extension (HE) and flexion (HF) strength, torque steadiness, and torque accuracy (TA). Methods: Twenty young adults (10 men, 10 women; age 24.0 ± 2.2 years) and 21 older adults (11 men, 10 women; age 65.4 ± 4.5 years) matched across age for height and body mass participated. Dominant leg HE and HF isometric strength was assessed by maximal voluntary contractions (MVC); relative (5, 25 and 50% MVC) and absolute (25 Nm) torque steadiness were assessed as standard deviation and coefficient of variation of torque fluctuations, and TA was determined as the mean deviation from target torque levels. Results: MVC was lower for HF than HE (p = 0.007), but HE had greater torque fluctuations (p < 0.05). For HE, the coefficient of variation of 5% MVC was greater for older than young adults (p < 0.05) and greater for women than men (p < 0.05). For HF torque steadiness there were no age or gender differences (p > 0.05). For both HE and HF, older adults were less accurate (higher TA) than their young counterparts at 25 Nm (p < 0.022). Conclusions: Our results indicate older as compared to young adults, and women as compared to men are less steady (greater torque fluctuations) in HE at 5% MVC target torque levels, but not at higher torque levels. For HF, torque steadiness is similar across low to high target torque levels in both genders and across younger and older adults. For both HE and HF, TA is impaired in older compared to young adults at absolute target torque levels, but not at relative torque levels.

Baseline Lower Extremity Strength and Subsequent Decline in Functional Performance at 6‐Year Follow‐Up in Persons with Lower Extremity Peripheral Arterial Disease

To evaluate associations between baseline lower extremity strength and decline in functional performance over 6 years of follow-up in men and women with lower extremity peripheral arterial disease (PAD). Prospective observational study. Three Chicago-area hospitals. Three hundred seventy-four men and women with PAD. Baseline isometric hip extension, hip flexion, knee flexion, and knee extension strength were measured using a musculoskeletal fitness evaluation chair. Usual and fastest-paced 4-m walking speed, 6-minute walk, and Short Physical Performance Battery (SPPB) were assessed at baseline and annually thereafter. Analyses were adjusted for age, sex, race, ankle-brachial index (ABI), comorbidities, and other confounders. In women with PAD, weaker baseline hip and knee flexion strength were associated with faster average annual decline in usual-pace 4-m walking speed (P trend <.001 and .02, respectively) and SPPB (P trend=.02 and .01, respectively). In women, weaker hip extension strength was associated with faster decline in usual-pace 4-m walking speed and SPPB (P trend=.01 and <.01, respectively). There were no significant associations between baseline strength and decline in 6-minute walk in women. There were no significant associations between any baseline strength measure and functional decline in men. Weaker baseline leg strength is associated with faster functional decline in nonendurance measures of functional performance in women with PAD but not in men with PAD.

Females with patellofemoral pain syndrome have weak hip muscles: a systematic review

Do females with patellofemoral pain syndrome have decreased hip muscle strength compared with the unaffected side and with healthy controls? A systematic review of observational studies published up to January 2008. Females with patellofemoral pain syndrome and healthy controls. Strength for at least one hip muscle group had to be included in the study. Hip muscle strength was recorded as force or torque. Five cross-sectional studies with a mean Newcastle-Ottawa Assessment Scale score of 6 out of 9 met the inclusion criteria. Strong evidence was found for a deficit in hip external rotation, abduction and extension strength, moderate evidence for a deficit in hip flexion and internal rotation strength, and no evidence for a deficit in hip adduction strength compared with healthy controls. Moderate evidence was found for a decrease in hip external rotation and abduction strength but no evidence for a decrease in hip extension, flexion, adduction and internal rotation strength compared with the unaffected side. Females with patellofemoral pain syndrome demonstrate a decrease in abduction, external rotation and extension strength of the affected side compared with healthy controls.

Lower Limb Strength in Sports-Active Transtibial Amputees

The aim of this study was to compare hip strength in sports-active transtibial (TT) amputees, sedentary TT amputees and sports-active non-amputees. Three 'active' (exercising recreationally at least three times per week) TT amputees, four 'inactive' or sedentary TT amputees and nine 'active' able-bodied persons (AB) underwent concentric and eccentric hip flexion and extension strength testing on both limbs on an isokinetic dynamometer at 60 and 120 degrees /s. Little strength asymmetry was noted between the limbs of the active TT amputees (8% and 14% at 60 and 120 degrees /s, respectively), their residual limb being slightly stronger. Inactive TT amputees demonstrated up to 49% strength asymmetry, their intact limb being the stronger. Active TT amputees demonstrated greater peak hip torques (Nm/kg) for all conditions and speeds compared to inactive TT amputees. Peak hip torques (Nm/kg), were greater in the active TT amputees' residual limb compared to AB. While inactive TT amputees and AB had similar flexion/extension ratios, active TT amputees exhibited a lower ratio indicating overdeveloped hip extensors with respect to their hip flexors. It is not known whether this is due to the demands of sport or exercise with a prosthetic limb, or remaining residual thigh atrophy.

Reliability of the hip examination in osteoarthritis: Effect of standardization

To assess the reliability of the physical examination of the hip in osteoarthritis (OA) among rheumatologists and orthopedic surgeons, and to evaluate the benefits of standardization. Thirty-five physical signs and techniques were evaluated using a 6 x 6 Latin square design. Subjects with mild to severe hip OA, based on physical and radiographic signs, were examined in random order prior to and following standardization of physical examination techniques. For dichotomous signs, agreement was calculated as the prevalence-adjusted bias-adjusted kappa (PABAK), whereas for continuous and ordinal signs a reliability coefficient was calculated using analysis of variance. A PABAK >0.60 and a reliability coefficient >0.80 were considered to indicate adequate reliability. Adequate post-standardization reliability was achieved for 25 (71%) of 35 signs. The most highly reliable signs included true and apparent leg length discrepancy > or =1.5 cm; hip flexion, abduction, adduction, and extension strength; log roll test for hip pain; internal rotation and flexion range of motion; and Thomas test for flexion contracture. The standardization process was associated with substantial improvements in reliability for a number of physical signs, although minimal or no change was noted for some. Only 1 sign, Trendelenburg's sign, was highly unreliable post-standardization. With the exception of gait, a comprehensive hip examination can be performed with adequate reliability. Post-standardization reliability is improved compared with pre-standardization reliability for some physical signs. The application of these findings to future OA studies will contribute to improved outcome assessments in OA.

Corticospinal Tract Abnormalities Are Associated with Weakness in Multiple Sclerosis

The association of MR imaging abnormalities with clinical disability in multiple sclerosis (MS) has been disappointing. This association might be improved by imaging specific functional systems in the central nervous system-for example, the motor system in a patient with weakness. Our aim was to assess the relationship between muscle strength in MS and corticospinal tract (CST) abnormalities detected with multimodality MR imaging of the brain. In 47 individuals with MS, diffusion tensor imaging (DTI) at 3T was used to reconstruct the intracranial CSTs. Tract profiles depicted the variation in T2 relaxation time, magnetization transfer ratio (MTR), and DTI-derived indices (fractional anisotropy and diffusivity) as a function of normalized position along the tract. Brain parenchymal fraction was calculated as a normalized measure of brain volume. Stepwise linear regression modeling was used to determine the MR imaging indices most closely related to ankle dorsiflexion and hip flexion strength assessed with quantitative dynamometry. Individuals with MS were significantly weak: Average ankle strength fell 1.7 SDs below the age-, handedness-, and sex-corrected healthy mean. Brain parenchymal fraction was not associated with weakness. A parsimonious model that includes MTR in the brain stem and MS clinical subtype explained 30%-45% of the variance in ankle and hip strength. The model was successfully applied to scans and strength data from the same individuals at an earlier time point. MR imaging abnormalities specific to the motor tract are associated with clinical dysfunction related to that tract. The relevant abnormalities are found in the brain stem, distant from the periventricular inflammatory lesions that are common in MS. This suggests that neurodegeneration, rather than primary inflammation, at least partially explains the findings.

サッカー選手の等速性筋力と MRI からみた下肢筋力特性

This study examined peculiarities in both muscle strength and cross-sectional area (CSA) among soccer players in comparison with those of archers as contrasting athletes. Subjects were 15 male soccer players and 9 male archers at N University. Measurement items were height, body weight (BW), isokinetic muscle strength (knee extension, knee flexion, hip extension, hip flexion) and CSA (psoas muscles). Isokinetic muscle strength (30, 120, 240°/sec.) was measured by Cybex6000 (Lumex Co.), and the psoas muscle CSA was determined using magnetic resonance imaging (Hitachi, Japan). Results were as follows : 1. There was no significant difference in isokinetic knee extension and flexion strength/BW at all angular velocities between soccer players and archers. 2. On isokinetic hip flexion strength/BW, the average values of soccer players were significantly higher at all angular velocities than those of archers. However, there was no significant difference in the average values of isokinetic hip extension strength at all angular velocities between the two groups. 3. The average value for the psoas muscle CSA in soccer players was significantly higher than that of archers. In this study, the biggest difference in muscle strength between soccer players and archers was hip flexion strength, and the CSA of the psoas muscle in soccer players, which is the main component of hip flexion, was significantly larger than that of archers. These findings showed the peculiarity of soccer players due to the constant demands of movements involved in ball kicking and running during practice and competition.

Reduced muscle radiological density, cross-sectional area, and strength of major hip and knee muscles in 22 patients with hip osteoarthritis

Background Patients with hip osteoarthritis (OA) typically suffer joint pain, and often experience muscular weakness. We hypothesized that substantial atrophy would manifest in multiple muscle groups along the affected limb, resulting in severe muscle dysfunction.Patients and methods We assessed 22 elderly patients with unilateral OA for maximal voluntary isometric strength of hip and knee muscles using a dynamometer that was developed for the purpose. Cross-sectional area (CSA) and radiological density (RD; in Hounsfield units: HU) of hip and knee muscles were assessed using CT. We determined SF-36, HHS, and EQ-5D.Results Hip extension, flexion, adduction, abduction, and knee extension strength were reduced (11– 29%; p < 0.01) in the OA limb relative to the healthy limb. Muscle CSA of hip extensors, flexors, adductors, knee extensors and flexors, but not hip abductors, was reduced (11–19%; p < 0.01) in the OA limb, where RD of all muscle groups except hip flexors was reduced (5–15 HU; p < 0.01). The clinical scores confirmed impairment.Interpretation Major muscles functioning around the hip and knee showed substantial loss of strength and mass, which contributes to the reduced ambulatory capacity of OA patients. Reduced muscle CSA could not fully explain the loss in strength. Infiltration with fat or other non-contractile components, as indicated by a reduced RD, in OA limb muscles was substantial.

Arthroscopic Psoas Tenotomy

Abstract Tenotomy may be indicated for psoas tendinitis or painful snapping if conservative treatment remains unsuccessful. Because of significant complications with open techniques, endoscopic operations have been developed. We present a new arthroscopic technique to access and release the psoas tendon from the hip joint. This procedure can be performed in addition to other arthroscopic procedures of the hip joint or alone. To exclude additional hip disease, a diagnostic round of the joint should be completed. After hip arthroscopy of the central compartment has been performed, traction is released and the 30° arthroscope is placed via the proximal anterolateral portal lying on the anterior femoral neck. The medial synovial fold can be identified. This fold lies slightly medially underneath the anteromedial capsule at the level of the psoas tendon. The arthroscope is turned toward the anterior capsule. Sometimes, the tendon shines through a thin articular capsule, or it may even be accessed directly via a hole connecting the hip joint and the iliopectineal bursa at the level of the anterior head–neck junction. If this cannot be done, an electrothermic probe is introduced via the anterior portal to make a 2-cm transverse capsular incision. The tendon is released with the back side of the electrothermic device turned to the iliacus muscle that lies anterior to the psoas tendon. A complete release is achieved when the tendon stumps can be seen gapping at a distance and the fibers of the iliacus muscle are visible. The first 9 patients who underwent surgery performed according to this technique developed no complications, and their hip flexion strength was restored to normal within 3 months.

Effects of creatine supplementation on nutritional status, muscle function and quality of life in patients with colorectal cancer—A double blind randomised controlled trial

Nutritional status frequently deteriorates during chemotherapy in cancer. This is associated with a poor outcome. Since creatine supplementation has shown promising results in various diseases, we investigated the effects of creatine on nutritional status in patients with colorectal cancer undergoing chemotherapy. Thirty patients with colorectal cancer undergoing chemotherapy were randomised to receive either creatine (n=16) or placebo (n=15) for 8 weeks. Body composition was determined with bioelectrical impedance analysis; muscle function by hand grip, hip flexion and knee extension strength and quality of life (QoL) was assessed by the QLQ30 questionnaire. Neither muscle function, body cell mass (BCM) nor QoL improved, but phase angle, a marker of BCM and cell integrity, increased significantly in the intervention patients (5.3+/-0.3 degrees to 5.4+/-0.2 degrees , P=0.030). Evaluating patients with different chemotherapy regimens, however, only intervention patients undergoing less aggressive chemotherapy were shown to benefit, increasing phase angle (5.11+/-0.22 degrees to 5.51+/-0.30 degrees , P=0.043) as well as BCM (27.22+/-2.85 to 29.60+/-3.54kg, P=0.043). Creatine failed to improve muscle mass or function and QoL in colorectal cancer patients but improved bioimpedance parameters that are predictive of poor outcome. Creatine might therefore be useful in patients with milder chemotherapy in order to maintain or increase BCM whereas patients undergoing aggressive chemotherapy however are not likely to benefit.

A Case of a Marathon Runner with a Non-Displaced Intertrochanteric Fracture Presenting as a Hip Flexor Strain

HISTORY: A 33-year-old male runner with no PMH presented to a hospital emergency department with left hip pain one day after running a marathon. He initially developed the hip pain at mile 21, stating that it was severe enough to cause him to stop running. He ultimately was able to finish the race by walking. He was then seen in the medical tent and given crutches after which he presented to a hospital emergency department. In the emergency department, he was unable to bear weight and complained of pain with hip flexion. The patient was treated with toradol and morphine and the pain improved. He was diagnosed with hip flexor tendonitis, prescribed an anti-inflammatory and was directed to follow up in the sports medicine clinic the next day. During his clinic visit, he presented ambulating with crutches and he did not relate any history of trauma or hip pain during his training program. He complained of increased pain with ambulation since the marathon. PHYSICAL EXAMINATION: Examination in the sports medicine clinic revealed guarding with left lower extremity weight bearing. There was full passive range of motion with hip flexion but mild pain with flexion and external rotation of the hip. Hip abduction and adduction strength were 5/5 and hip flexion strength was limited secondary to pain. He also had a positive iliopsoas clunk and a negative Ober's sign. There was no ASIS tenderness. DIFFERENTIAL DIAGNOSIS: Femoral neck stress fracture Iliopsoas strain Acetabular labral tear TEST AND RESULTS: Left hip frontal and lateral radiographs: -Non-displaced left hip subcapsular fracture Nuclear medicine multiphase bone scan: -Left intertrochanteric stress fracture FINAL/WORKING DIAGNOSIS: Non-displaced completed femoral neck fracture TREATMENT AND OUTCOMES Admitted to another institution and underwent successful hip pinning for completed femoral neck fracture.

The Role of Hip Muscle Function in the Treatment of Patellofemoral Pain Syndrome

Background Previous literature has associated hip weakness with patellofemoral pain syndrome. Hypothesis Improvements in hip strength and flexibility are associated with a decrease in patellofemoral pain. Study Design Cohort study; Level of evidence, 2. Methods Thirty-five patients with patellofemoral pain syndrome, aged 33 ± 16 years (29 women, 6 men; 43 knees), were evaluated and placed on a 6-week treatment program. Hip flexion, abduction, and adduction strengths, Thomas and Ober test results, and visual analog scale scores for pain with activities of daily living as well as with exercise were documented on initial evaluation and again 6 weeks later. Treatment consisted of strength and flexibility exercises primarily focusing on the hip. Results Hip flexion strength improved by 35% ± 8.4% in 26 lower extremities treated successfully, compared with –1.8% ± 3.5% in 17 lower extremities with an unsuccessful outcome (P< .001). Before treatment, there were positive Ober test results in 39 of 43 lower extremities; positive Thomas test results were seen in 31 of 43 lower extremities. A successful outcome with a concurrent normalized Ober test result was seen in 83% (20/24) of lower extremities, and successful outcomes with normalized Thomas test results were seen in 80% (16/20) of lower extremities. A combination of improved hip flexion strength (> 20%) as well as normal Ober and Thomas test results was seen in 93% of successfully treated cases (14/15 lower extremities), compared with 0% success (0/5 lower extremities) if there was no change in hip flexion strength (< 20%) and if Ober and Thomas test results remained positive. Conclusions Improvements in hip flexion strength combined with increased iliotibial band and iliopsoas flexibility were associated with excellent results in patients with patellofemoral pain syndrome.

Risk Factors for Noncontact Ankle Sprains in High School Athletes

Background Ankle sprains are among the most common sports injuries. Hypothesis Poor balance as measured on a balance board and weakness in hip abduction strength are associated with an increased risk of noncontact ankle sprains in high school athletes. Study Design Cohort study; Level of evidence, 2. Methods One hundred sixty-nine high school athletes (101 male athletes, 68 female athletes) from football, men's basketball, men's soccer, women's gymnastics, women's basketball, and women's soccer were observed for 2 years. Balance in single-limb stance on an instrumented tilt board and hip flexion, abduction, and adduction strength (handheld dynamometer) were assessed in the preseason. Body mass, height, generalized ligamentous laxity, previous ankle sprains, and ankle tape or brace use were also documented. Results There were 20 noncontact inversion ankle sprains. Balance ability (P= .72), hip abduction strength (P= .66), hip adduction strength (P= .41), and hip flexion strength (P= .87) were not significant risk factors for ankle sprains. The incidence of grade II and grade III sprains was higher in athletes with a history of a previous ankle sprain (1.12 vs 0.26 per 1000 exposures, P< .05). A higher body mass index in male athletes was associated with increased risk (P< .05). The combination of a previous injury and being overweight further increased risk (P< .01). Conclusion Balance as measured on a balance board and hip strength were not significant indicators for noncontact ankle sprains. The apparent high injury risk associated with the combination of a history of a previous ankle sprain and being overweight in male athletes warrants further examination.

Type of acute hamstring strain affects flexibility, strength, and time to return to pre-injury level

Objectives: To investigate possible links between aetiology of acute, first time hamstring strains in sprinters and dancers and recovery of flexibility, strength, and function as well as time to return...

The Influence of Lean Body Mass and Leg Muscle Strength on 6-Minute Walk Test Performance in Children with Cystic Fibrosis

Purpose: Exercise capacity, measured by the 6-minute walk test (6MWT) is impaired in patients with cystic fibrosis (CF) and is related to their survival and quality of life. 6MWT performance may be influenced or explained by lung function, lean body mass (LBM), or muscle strength. Therefore, the purpose of this study was to determine the relationships between leg muscle strength and 6MWT as well as LBM and 6MWT in children with CF as compared to healthy peers. Methods: Subjects with CF (n=21, mean age 10.5 yrs, mean FEV, 65% predicted) and age- and sexmatched healthy controls were tested for LBM and lower extremity muscle strength. Measurements of skin folds were used to determine LBM. Strength of bilateral hip flexors, knee extensors, and ankle dorsiflexors was determined via hand-held dynamometry. Subjects then completed the 6MWT. A Mann-Whitney U test was used to make between group comparisons for height, weight, LBM, muscle strength, and 6MWT distance. A Kendall's Tau was used to assess within group correlations between the strength of each muscle tested and both LBM and 6MWT distance. Results: Subjects with CF had significantly lower LBM (23.7 ± 8.5 kg vs. 31.4 ± 12.0 kg) and 6MWT (490 ± 77 m vs. 557 ± 94 m) than controls. Hip flexion and ankle dorsiflexion strength was also significantly lower in CF than controls. The 6MWT distance correlated significantly with bilateral hip flexion (r = 0.37-0.39) and knee extension strength (r = 0.31-0.37) in CF. There was no relationship between any strength measure and 6MWT distance in controls. Strength correlated moderately with LBM in both groups. LBM did not correlate with 6MWT in either group. Conclusions: Exercise capacity as measured by 6MWT is impaired in children with CF and is partially related to decreased leg muscle strength. These findings suggest that leg muscle strength, not LBM, is related to 6MWT performance in children with CF.

EFFECTS OF HIP FLEXOR TRAINING ON SPRINT, SHUTTLE RUN, AND VERTICAL JUMP PERFORMANCE

Although hip flexion is integral in sports, hip flexion exercises are seldom emphasized in strength and conditioning for sports performance. This study aimed to determine whether a hip flexor resistance-training program could improve performance on a variety of tasks. Thirteen men and 11 women completed an 8-week hip flexion resistance-training program. Eleven men and 13 women served as controls. Isometric hip flexion strength, 40-yd dash time and the time for the first 10-yds, 4 × 5.8-m shuttle run time, and vertical jump height were evaluated at the beginning and end of the training and control period. Improvements were observed in the training group but not in the control group. Individuals in the training group improved hip flexion strength by 12.2% and decreased their 40-yd and shuttle run times by 3.8% and 9.0%, respectively. An increase in hip flexion strength can help to improve sprint and agility performance for physically active, untrained individuals.