Running biomechanics differ during and after pregnancy compared to females who have never been pregnant

BACKGROUND

Perinatal running participation has increased recently; however, pregnancy related symptoms can limit activity. Perinatal running biomechanics could inform interventions to help perinatal individuals maintain an active lifestyle.

RESEARCH QUESTION

Are perinatal running biomaechanics and muscle activation different compared to nulligravida females?

METHODS

Sixteen pregnant participants completed self-selected velocity running during second trimester (2 T), third trimester (3 T), and postpartum (PP) and 16 matched controls completed these procedures once in this case control study. Kinematic, kinetic, and electromyography (EMG) data were collected using a motion capture system, force plates, and EMG electrodes. Peak trunk, pelvis, hip, knee, and ankle kinematics and hip, knee, and ankle moments during stance phase, and average and peak erector spinae (ES), gluteus maximus (GMax), and gluteus medius (GMed) EMG amplitude and duration of activation during stance and swing phases were calculated. Independent t-tests were used to compare 2 T, 3 T, and PP to control participants (α < 0.05).

RESULTS

Running velocity was slower during 3 T compared to control participants. At all pregnancy timepoints compared to the control group, peak trunk contralateral rotation was smaller. During 2 T and 3 T peak hip flexor moments were smaller. At 3 T pelvis contralateral rotation was smaller, ES average amplitude was greater during swing, GMax percent duration during stance and GMed percent duration during swing were smaller. At PP trunk flexion was smaller and knee abduction was greater (all p < 0.05).

CONCLUSIONS

Decreased running velocity may help offset increased demand during pregnancy. During 3 T, greater ES activation, smaller trunk and pelvis motion, and altered gluteal activation could indicate trunk rigidity combined with modified hip stabilizer muscle utilization. During PP, the rigid trunk combined with greater knee abduction may indicate hip and trunk strength deficits. Altered trunk and hip motion and activation could be relevant to pathologies such as perinatal low back, pelvic girdle, or knee pain.

Determining fall risk change throughout pregnancy: the accuracy of postpartum survey and relationship to fall efficacy

All epidemiological studies on pregnancy fall risk to date have relied on postpartum recall. This study investigated the accuracy of postpartum recall of falls that were reported during pregnancy, including assessment of fall efficacy as a possible reason for recall inaccuracy. Twenty participants reported fall experiences weekly during pregnancy, but one participant was excluded as an outlier. A fall efficacy questionnaire was completed every six weeks during pregnancy. A postpartum survey to mimic previous studies (Dunning, Lemasters, and Bhattacharya 2010; Dunning et al. 2003) was delivered to determine recall accuracy. Postpartum recall of fall events each gestational month matches the previous study (Dunning, Lemasters, and Bhattacharya 2010). However, recall of falls is 16% underestimated and recall of all fall events is 30% overestimated in postpartum survey. There is a slight relationship between fall efficacy and true falls, but not between fall efficacy and fall recall. Our study suggests fall risk needs to be intermittently surveyed throughout pregnancy rather than assessed via postpartum survey.Practitioner summary: This study investigated the accuracy of postpartum survey of fall risk during pregnancy and the possibility of fall efficacy as a covariate. We used three corresponding surveys. We found inaccuracies in postpartum survey, not explain by fall efficacy.

Center of pressure characteristics differ during single leg stance throughout pregnancy and compared to nulligravida individuals

BACKGROUND

Falls are common during pregnancy and present potential for injury to the pregnant individual and the baby.

RESEARCH QUESTION

Do center of pressure characteristics during single leg stance differ between participants during and after pregnancy and nulligravida participants in the presence and absence of visual input?

METHODS

Nineteen pregnant participants completed testing during the second trimester, the third trimester, and 4-6 months post-partum. Matched, nulligravida females completed testing once. All participants performed single leg stance on a force platform on each limb for up to 20 s with eyes open and with eyes closed. Center of pressure characteristics were compared between pregnant and nulligravida females using three separate 2 × 2 mixed way ANOVAs, one for each pregnancy time point (second trimester, third trimester, and post-partum) with Bonferroni correction.

RESULTS

Pregnant females demonstrated smaller single leg stance time with eyes closed during the third trimester. During the second and third trimester, pregnant participants demonstrated smaller sway and sway velocity across eyes open and eyes closed conditions. During the third trimester and post-partum, pregnant participants demonstrated greater median frequency of the center of pressure data. Pregnant participants also demonstrated smaller sample entropy in the anteroposterior direction during the second and third trimesters and in the mediolateral direction during the second trimester.

SIGNIFICANCE

The decreased total sway and sway velocity observed during pregnancy may reflect rigidity or a protective strategy during single limb stance. Additionally, center of pressure data were less smooth and more repetitive during pregnancy indicating robust differences in postural control strategies and potentially increased fall risk. Because single limb stance is a component of many activities of daily living, the single limb stance task may have clinical utility for testing or training balance in this population with a goal of decreasing falls.

Do people with low back pain walk differently? A systematic review and meta-analysis

BACKGROUND

The biomechanics of the trunk and lower limbs during walking and running gait are frequently assessed in individuals with low back pain (LBP). Despite substantial research, it is still unclear whether consistent and generalizable changes in walking or running gait occur in association with LBP. The purpose of this systematic review was to identify whether there are differences in biomechanics during walking and running gait in individuals with acute and persistent LBP compared with back-healthy controls.

METHODS

A search was conducted in PubMed, CINAHL, SPORTDiscus, and PsycINFO in June 2019 and was repeated in December 2020. Studies were included if they reported biomechanical characteristics of individuals with and without LBP during steady-state or perturbed walking and running. Biomechanical data included spatiotemporal, kinematic, kinetic, and electromyography variables. The reporting quality and potential for bias of each study was assessed. Data were pooled where possible to compare the standardized mean differences (SMD) between back pain and back-healthy control groups.

RESULTS

Ninety-seven studies were included and reviewed. Two studies investigated acute pain and the rest investigated persistent pain. Nine studies investigated running gait. Of the studies, 20% had high reporting quality/low risk of bias. In comparison with back-healthy controls, individuals with persistent LBP walked slower (SMD = -0.59, 95% confidence interval (95%CI): -0.77 to -0.42)) and with shorter stride length (SMD = -0.38, 95%CI: -0.60 to -0.16). There were no differences in the amplitude of motion in the thoracic or lumbar spine, pelvis, or hips in individuals with LBP. During walking, coordination of motion between the thorax and the lumbar spine/pelvis was significantly more in-phase in the persistent LBP groups (SMD = -0.60, 95%CI: -0.90 to -0.30), and individuals with persistent LBP exhibited greater amplitude of activation in the paraspinal muscles (SMD = 0.52, 95%CI: 0.23-0.80). There were no consistent differences in running biomechanics between groups.

CONCLUSION

There is moderate-to-strong evidence that individuals with persistent LBP demonstrate differences in walking gait compared to back-healthy controls.

An exploratory analysis of gait biomechanics and muscle activation in pregnant females with high and low scores for low back or pelvic girdle pain during and after pregnancy

BACKGROUND

The purpose of this study was to compare gait kinematics, kinetics, and muscle activation between pregnant females with high and low scores for low back and/or pelvic girdle pain during and after pregnancy.

METHODS

Twenty participants tested during second trimester, third trimester, and again post-partum. At each session, motion capture, force plates, and surface electromyography data were captured during self-selected velocity over-ground walking. Participants completed the Quebec Back Pain Disability Scale (QBPDS) and were assigned to high (QBPDS ≥15) or low pain groups (QBPDS <15) based on third trimester scores. Two-way mixed model ANOVAs were used to compare high and low pain groups over time.

FINDINGS

Nine participants met the high pain group criteria and 11 were low pain. During second trimester the high pain group compared to the low pain group demonstrated smaller peak hip flexor moments, total hip work, percent hip contribution to work, and larger percent ankle contribution to work. Pregnant females demonstrated greater hip, knee, and ankle moments, ankle work, and gluteus maximus muscle activation third trimester than second trimester.

INTERPRETATION

Reduced hip and greater ankle contribution to work in the high pain group during second trimester could indicate decreased hip utilization early in pregnancy and may contribute to disability as pregnancy progresses. It is also possible kinetic differences during second trimester reflect an early strategy to reduce pain by avoiding hip joint loading. Increased moments and work during third trimester indicate a clinical imperative to better prepare pregnant females to accommodate increased joint loading and muscular demand.

Limb preference impacts single-leg forward hop limb symmetry index values following ACL reconstruction

Following anterior cruciate ligament (ACL) reconstruction limb dominance for performing tasks is not considered when making rehabilitation progression decisions. The purpose of this study was to determine if strength and functional outcomes differ between individuals who injured their preferred or nonpreferred jumping limb and to determine if these same outcomes differ between individuals who injured their preferred or nonpreferred limb used to kick a ball. A secondary purpose was to determine the association of quadriceps strength and single-leg forward hop performance with patient self-reported function. Forty individuals with ACL reconstruction (age = 20.0 ± 4.6 years, height = 174.2 ± 12.7 cm, mass = 71.2 ± 12.7 kg, time since surgery = 5.3 ± 0.8 months) were included in the study. Primary outcome measures included, International Knee Documentation Committee Subjective Knee Form (IKDC) scores, quadriceps limb symmetry index (LSI) values, and single-leg forward hop LSI values. Limb preference was defined two ways, kicking a ball and performing a unilateral jump. There were no significant differences between groups based on injury to the preferred limb to kick a ball for any of the outcome variables. Individuals who injured their nonpreferred jumping limb demonstrated significantly (p = 0.05, d = 0.77) lower single-leg forward hop LSI values (81.1% ± 19.5%) compared to individuals who injured their preferred jumping limb (94.1% ± 12.6%), but demonstrated no differences in IKDC scores or quadriceps LSI values. Quadriceps LSI and single-leg forward hop LSI explained 73% of the variance in IKDC scores, but quadriceps LSI had the strongest association (r = 0.790). These findings suggests that limb preference influences single forward hop LSI values and should be considered following ACL reconstruction.

Quadriceps Strength Influences Patient Function More Than Single Leg Forward Hop During Late-Stage ACL Rehabilitation

BACKGROUND

A comprehensive battery of tests are used to inform return to play decisions following anterior cruciate ligament (ACL) reconstruction. Performance measures contribute to patient function, but it is not clear if achieving symmetrical performance on strength and hop tests is sufficient or if a patient also needs to meet minimum unilateral thresholds.

HYPOTHESIS/PURPOSE

To determine the association of quadriceps strength and single-leg forward hop performance with patient-reported function, as measured by the IKDC Subjective Knee Form (IKDC), during late-stage ACL rehabilitation. A secondary purpose was to determine which clinical tests were the most difficult for participants to pass.

STUDY DESIGN

Descriptive Laboratory Study.

METHODS

Forty-eight individuals with a history of ACL-R (32 female, 16 male; mean±SD age=18.0±2.7 y; height=172.4±7.6 cm; mass=69.6±11.4 kg; time since surgery=7.7±1.8 months; IKDC=86.8±10.6) completed the IKDC survey, quadriceps isometric strength, and single-leg forward hop performance. The relationship between IKDC scores and performance measures (LSI and involved limb) was determined using stepwise linear regression. Frequency counts were used to determine whether participants met clinical thresholds (IKDC ≥ 90%, quadriceps and single-leg forward hop LSI ≥ 90%, quadriceps peak torque ≥ 3.0 Nm/kg, and single-leg forward hop ≥ 80% height for females and ≥ 90% height for males).

RESULTS

Quadriceps LSI and involved limb peak torque explained 39% of the variance in IKDC scores while measures of single-leg forward hop performance did not add to the predictive model. Nearly 90% of participants could not meet established clinical thresholds on all five tests and quadriceps strength (LSI and peak torque) was the most common unmet criteria (71% of participants).

CONCLUSIONS

During late-stage ACL rehabilitation deficits in quadriceps strength contribute more to patient function and are greater in magnitude compared to hop test performance.

LEVEL OF EVIDENCE

Cross-Sectional Study, Level 3.

Persons with femoroacetabular impingement syndrome exhibit altered pelvifemoral coordination during weightbearing and non-weightbearing tasks

BACKGROUND

Previous studies have reported that persons with femoroacetabular impingement syndrome (FAIS) have diminished posterior tilt of the pelvis during functional tasks. It is not known how this movement impairment impacts pelvifemoral coordination during weightbearing and non-weightbearing movements.

METHODS

Fifteen persons with a diagnosis of FAIS and 15 matched controls performed a deep squat (weightbearing) and a maximum height stepping task (non-weightbearing). Peak hip flexion, posterior pelvis tilt excursion, and the ratio of sagittal plane pelvis to femur motion during the period of pelvis posterior tilt were calculated for each task. Two factor ANOVAs were used to evaluate differences between groups and tasks.

FINDINGS

With regards to peak hip flexion, there were no significant group differences for either task. When averaged across tasks, the FAIS group exhibited significantly less posterior tilt excursion (12.1° (SD 9.1°) vs 20.6° (SD 9.3°)) and smaller pelvifemoral ratios (0.24 (SD 0.14) vs 0.39 (SD 0.16)) compared to the control group.

INTERPRETATION

Persons with FAIS exhibit altered pelvifemoral coordination regardless of weightbearing status. This finding suggests that decreased hip and/or lumbopelvic mobility may contribute to altered movement patterns at the hip.

Reliability of Hip Rotation Range of Motion in Supine and Seated Positions

CONTEXT

Hip rotation range of motion (ROM) is commonly assessed in individuals with lower extremity or spine pathology. It remains unknown which hip rotation ROM testing position is most reliable.

OBJECTIVE

To compare interrater and intrarater reliabilities between hip internal rotation (IR) and external rotation (ER) ROM in supine and seated positions.

STUDY DESIGN

Controlled laboratory study.

SETTING

University research laboratory.

PARTICIPANTS

A total of 19 participants (11 females and 8 males; age = 23.5 [1.2] y; height = 173.2 [8.6] cm; and mass = 69.2 [13.4] kg) without hip, knee, low back, or sacroiliac pain within the preceding 3 months or history of hip or low back surgery were recruited.

INTERVENTIONS

Three testers obtained measures during 2 testing sessions. Passive supine and seated hip IR and ER ROM were performed with the hip and knee flexed to 90°.

MAIN OUTCOME MEASURES

The primary outcome measures were hip IR and ER ROM in supine and seated positions (in degrees). Interrater and intrarater reliabilities were calculated using intraclass correlation coefficients (ICCs). Minimal detectable change was calculated. Differences between supine and seated hip IR and ER ROM values were assessed using paired t tests (significance level was .05).

RESULTS

Supine hip IR and ER ROM interrater and intrarater reliabilities were excellent (ICC = .75-.91). Seated hip IR ROM interrater and intrarater reliabilities were good (ICC = .64-.71). Seated hip ER ROM interrater reliability was good (ICC = .65), and intrarater reliabilities were good to excellent (ICC = .65-.82). Minimal detectable change values for supine and seated hip IR and ER ROM ranged from 6.1° to 8.6°. There were significant differences between supine and seated positions for hip IR and ER ROM (41.6° vs 44.5°; P < .01 and 53.0° vs 44.2°; P < .01, respectively).

CONCLUSION

Supine hip rotation had higher interrater and intrarater reliabilities. Hip IR and ER ROM values differed significantly between supine and seated positions and should not be used interchangeably.

COMPARISON OF CLINICAL FATIGUE PROTOCOLS TO DECREASE SINGLE-LEG FORWARD HOP PERFORMANCE IN HEALTHY INDIVIDUALS

BACKGROUND

Return to activity decisions after anterior cruciate ligament reconstruction (ACL-R) are limited by functional performance tests often performed in a non-fatigued state. Fatigue can improve test sensitivity, but current methods to induce fatigue are typically bilateral tasks or focus on the quadriceps muscle in isolation.

HYPOTHESIS/PURPOSE

To determine the effects of a two-minute lateral step-down fatigue test compared to a 30-second side-hop test on single-leg forward hop distance in healthy individuals. It was hypothesized that participants would demonstrate decreased hop distance with both tests, but the two-minute lateral step-down fatigue test would result in greater deficits in single-leg forward hop distance.

STUDY DESIGN

Randomized crossover.

METHODS

Twenty healthy participants (16 females, 4 males; age = 23.7±3.0 years, height = 153.8±36.2 cm; mass = 64.4±12.8 kg; Tegner = 6.8±1.2) were asked to perform single-leg forward hop for distance pre- and post-fatigue. Participants were randomly assigned to one of the two fatigue tests, 30-second side-hop or 2-minute lateral step-down test, during the first visit. They returned within a week and performed the same sequence of tests but underwent whichever fatigue test was not assigned at the prior visit.

RESULTS

There was a significant decrease (p < 0.001) in single-leg forward hop distance following the 30-second side-hop test (pre = 134.1±23.7 cm, post = 126.2±24.4 cm) and the two-minute lateral step-down test (pre = 135.0±26.1 cm, post = 122.7±27.4 cm). The decrease in hop distance was significantly greater (p < 0.001) for the two-minute lateral step-down test compared to the 30-second side-hop test.

CONCLUSION

The two-minute lateral step-down test resulted in a greater decrease in hop performance compared to the 30-second side-hop test. The results establish a threshold for expected changes that occur in a healthy population and that can then be compared with an injured athlete population. The two-minute lateral step-down exercise may be an effective method of inducing fatigue to better mimic performance in a sports environment to inform return-to-sport decisions.

LEVEL OF EVIDENCE

Level 1b- Therapy.

THE RELIABILITY OF FABER TEST HIP RANGE OF MOTION MEASUREMENTS

BACKGROUND

The Flexion ABduction External Rotation (FABER) test is typically used as a provocation special test, but has also been used as a measurement of combined hip range of motion (ROM). It is thought that limited ROM with this measurement may be indicative of hip pathology. To date, normative data, reliability, and minimal detectable change (MDC) of such measurements have not been established.

PURPOSE

To determine normative FABER height, assess inter- and intra-rater reliability and MDC for FABER, and compare traditional FABER measurements to methods which account for differences in thigh length.

STUDY DESIGN

Descriptive laboratory reliability study.

METHODS

Nineteen healthy participants without low back, hip, or knee pain in the preceding three months were recruited. Measurements were performed during two sessions (three to seven days between sessions) by three clinicians. FABER height and thigh length measurements were performed. Thigh length normalized FABER range of motion (ROM) and side-to-side FABER ROM symmetry were calculated. One tester also measured FABER with a digital inclinometer. Inter- and intra-rater reliability were calculated using interclass correlation coefficients (ICC) and mean MDC values were calculated.

RESULTS

Mean values for FABER height and normalized FABER ROM were 12.4 ± 2.8 cm and 0.30 ± 0.07, respectively. Inter-rater reliability for FABER and normalized FABER were good (ICC 0.67-0.68) and between session intra-rater reliability were good to excellent (ICC 0.76-0.86). Mean FABER and normalized FABER ROM MDC were 3.7 cm and 0.04, respectively. Mean FABER ROM symmetry was 2.0 ± 0.9 cm with poor inter-rater reliability (ICC 0.20), poor to good intra-rater reliability (ICC 0.38-0.66), and mean MDC of 4.0 cm. FABER measured with a ruler, normalized FABER ROM, and inclinometry all resulted in excellent intra-rater reliability, with the highest ICC being demonstrated for inclinometry (ICC 0.86, 0.86, and 0.91).

CONCLUSIONS

Overall, FABER measurements were reliable, whether normalized to thigh length or not. Furthermore, use of inclinometry may increase reliability. Reliability was poor to good when assessing symmetry between limbs.

LEVEL OF EVIDENCE

Level 3.

Sagittal plane pelvis motion influences transverse plane motion of the femur: Kinematic coupling at the hip joint

Previous studies have suggested that internal femur rotation can influence sagittal pelvis motion. This indicates that there may be kinematic "coupling" of these two segments. The purpose of the current study was to determine whether there is a consistent and predictable kinematic relationship between the pelvis and the femur. Sixteen healthy subjects (nine females, seven males) performed three trials of maximum anterior and posterior pelvis tilt at four different hip flexion angles (0°, 30°, 60°, and 90°). Ordinary least squares regressions were used to calculate the ratio of transverse femur motion to sagittal pelvis motion using the mean kinematic curves during maximum anterior and posterior pelvis tilting. R(2) values were used to assess the strength of the kinematic relationship between these segments at each hip flexion angle. The ratios of transverse femur motion to sagittal pelvis motion were consistent across all hip flexion angles during anterior and posterior pelvis tilting (range 0.23-0.32; R(2) values greater than 0.97). On average, for every 5° of anterior pelvis tilt there was 1.2-1.6° of internal femur rotation and the converse was true for posterior pelvis tilt and external femur rotation. Our findings suggest that altered pelvis movement in the sagittal plane may influence transverse femur motion. The observed coupling behavior between the pelvis and femur may have implications for musculoskeletal conditions in which excessive internal femur rotation has been deemed contributory to symptoms (i.e. femoroacetabular impingement).