Psychological and physiological effects of an acute bout of yoga before a simulated academic exam in university students

Objective: Test anxiety is common among nursing students. Yoga is one form of physical activity which may be beneficial for pretest anxiety. Participants: Thirteen undergraduate students (85% nursing majors, 15% awaiting program entry, 20 ± 4.9 years of age) completed the crossover design study. Methods: Participants completed a yoga or control intervention (independent quiet study) on opposing testing days. At three time points, participants provided ratings of anxiety (visual analog scales), saliva samples for cortisol and alpha amylase, and seated heart rate variability (HRV, time and frequency domains) was recorded. Results: Yoga prior to a simulated exam had a positive impact on subjective measures of stress but did not positively impact cortisol or HRV compared to the control condition. Conclusions: There may be benefits to participating in 30 min of moderate intensity yoga for reduced perception of stress before a scholarly examination. Further research regarding the impacts of acute yoga on physiological measures of HRV and/or cortisol are warranted.

Moms on the move: A qualitative exploration of a postpartum group exercise program on physical activity behaviour at three distinct time points

PURPOSE

Physical activity (PA) after the birth of a child is associated with improved physical and mental health benefits. The aim of the study was to explore new mothers' experiences of PA before and after participation in a group-based PA program for new mothers. The study has three research questions: how new mothers felt; 1) about PA after the birth of their child 2) about engaging in a group-based PA program and 3) after the program ended about ongoing PA engagement.

METHODS

We conducted an 8-week bi-weekly PA program for postpartum women. To understand the experience of postpartum women engaging in a group-based PA program we conducted one-on-one semi-structured interviews before, after, and at 6-month follow-up.

RESULTS

Of the n = 21 participants in the Moms on the Move study; n = 17 completed pre interviews.s. One primary theme emerged from pre-program interviews where mothers shared how they were lost as to where to start PA. Post-program interviews produced two primary themes; engaging in PA helped mothers, and mothers learned to rethink PA.

CONCLUSIONS

Postpartum women who participated in this group-based PA program had positive benefits to their mental and physical health and were able to alter their PA behaviour.

Association Between Knee Joint Muscle Activation and Knee Joint Moment Patterns During Walking in Moderate Medial Compartment Knee Osteoarthritis: Implications for Secondary Prevention

OBJECTIVE

To determine associations between knee moment features linked to osteoarthritis (OA) progression, gait muscle activation patterns, and strength.

DESIGN

Cross-sectional secondary analysis.

SETTING

Gait laboratory.

PARTICIPANTS

Convenience sample of 54 patients with moderate, medial knee OA (N=54).

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Knee moments and quadriceps and hamstrings activation were examined during walking. Knee extensor and flexor strength were measured. Waveform patterns were extracted using principal component analysis. Each measured waveform was scored against principal components (PCs) that captured overall magnitude (PC1) and early to midstance difference (PC2) features, with higher PC2 scores interpreted as greater moment differential and more prolonged muscle activity. Correlations were calculated between moment PC scores and muscle PC and strength scores. Regression analyses determined moment PC score variance explained by muscle PC scores and strength.

RESULTS

All correlations for knee adduction moment difference feature (KAMPC2) and prolonged muscle activity (PC2) were significant (r=-0.40 to -0.54). Knee flexion moment difference feature (KFMPC2) was significantly correlated with all quadriceps and medial hamstrings PC2 scores (r=-0.47 to -0.61) and medial hamstrings magnitude feature (PC1) (r=-0.52). KAMPC2 was significantly correlated with knee flexor strength (r=0.43), and KFMPC2 was significantly correlated with knee extensor (r=0.60) and flexor (r=0.55) strength. Regression models including muscle PC2 scores and knee flexor strength explained 46% of KAMPC2 variance, whereas muscle PC2 scores and knee extensor strength explained 59% of KFMPC2 variance.

CONCLUSIONS

Muscle activation patterns and strength explained significant variance in moment difference features, highest for the knee flexion moment. This supports that exercises such as neuromuscular training, focused on appropriate muscle activation patterns, and strengthening have the potential to alter dynamic loading gait patterns associated with knee OA clinical progression.

Does body size impact muscle recruitment during law enforcement physical control simulator use?

This study examined muscle activation during the 'push-pull' component of law enforcement physical abilities testing and assessed activation differences based on sex, height, and body mass index. Fifty participants (40 male) completed the 'push-pull' task while surface electromyograms were recorded from ten upper and lower extremity muscles, and six trunk muscles. Muscle activation was amplitude-normalized to maximum voluntary isometric contraction and compared between sexes and tertiles of height and body mass index (BMI). Women had significantly higher activation of anterior deltoid and pectoralis major on the pull, and posterior deltoid and triceps on the push. Significant differences largely remained after controlling for body size in regression analyses. The lowest tertile of height had significantly higher triceps activity on the push. The highest tertile of BMI had significantly higher rectus abdominus and external obliques activity on the pull, and external obliques activation on the push. Practitioner summary: Muscle activation during the 'push-pull' component of law enforcement standardised testing was examined, including differences based on sex, height, and BMI. Minimal differences existed between sexes (females had higher deltoid, pectoralis major, triceps activity), height (shorter people had higher triceps activity) and BMI tertiles (larger people had more abdominal activity). Abbreviations: ANOVA: analysis of variance; BMI: body mass index; COPAT: correctional officer's physical abilities test; EMG: electromyogram; IMU: inertial measurement unit; MVIC: maximum voluntary isometric contraction; PARE: physical abilities requirement evaluation; PCS: physical control simulator; POPAT: police officer's physical abilities test; RMS: root mean square.

Clinical and biomechanical changes following a 4-month toe-out gait modification program for people with medial knee osteoarthritis: a randomized controlled trial

OBJECTIVE

To compare changes in knee pain, function, and loading following a 4-month progressive walking program with or without toe-out gait modification in people with medial tibiofemoral knee osteoarthritis.

DESIGN

Individuals with medial knee osteoarthritis were randomized to a 4-month program to increase walking activity with (toe-out) or without (progressive walking) concomitant toe-out gait modification. The walking program was similar between the two groups, except that the gait modification group was trained to walk with 15° more toe-out. Primary outcomes included: knee joint pain (WOMAC), foot progression angles and knee joint loading during gait (knee adduction moment (KAM)). Secondary outcomes included WOMAC function, timed stair climb, and knee flexion moments during gait.

RESULTS

Seventy-nine participants (40 in toe-out group, 39 in progressive walking group) were recruited. Intention-to-treat analysis showed no between-group differences in knee pain, function, or timed stair climb. However, the toe-out group exhibited significantly greater changes in foot progression angle (mean difference = -9.04° (indicating more toe-out), 95% CI: -11.22°, -6.86°; P < 0.001), late stance KAM (mean difference = -0.26 %BW*ht, 95% CI: -0.39 %BW*ht, -0.12 %BW*ht, P < 0.001) and KAM impulse (-0.06 %BW*ht*s, 95% CI: -0.11 %BW*ht*s, -0.01 %BW*ht*s; P = 0.031) compared to the progressive walking group at follow-up. The only between-group difference that remained at a 1-month retention assessment was foot progression angle, with greater changes in the toe-out group (mean difference = -6.78°, 95% CI: -8.82°, -4.75°; P < 0.001).

CONCLUSIONS

Though both groups experienced improvements in self-reported pain and function, only the toe-out group experienced biomechanical improvements.

TRIALS REGISTRY NUMBER

NCT02019108.

Contralateral limb foot rotation during unilateral toe-in or toe-out walking in people with knee osteoarthritis

BACKGROUND

Gait modification is a treatment approach often used for a variety of neuromuscular and musculoskeletal pathologies. Gait modification is commonly applied to a single limb, as is done with foot rotation (FR) in people with knee osteoarthritis (KOA). However, the extent to which gait changes observed in the trained limb are also exhibited in the untrained, contralateral limb during a training session is unknown.

RESEARCH QUESTION

The purpose of this study was to examine the within-limb FR differences across four unilateral FR modifications compared to natural walking.

METHODS

Sixteen individuals with KOA walked on a treadmill while performing four different FR conditions: 10° toe-in, 0°, 10° toe-out and 20° toe-out. Motion capture was conducted to track FR magnitude after five minutes of practice.

RESULTS

The change in contralateral FR angle compared to natural walking significantly increased during toe-in 10° walking (3.1°) compared to toe-out -10° and -20° walking (-1.2° and -1.5°, respectively). As expected, the ipsilateral FR angle was significantly different between all conditions.

SIGNIFICANCE

These results suggest that small, but statistically significant changes in the untrained contralateral limb FR are observed during FR training of the ipsilateral limb. This may indicate a desire for symmetry, or a compensation when modifying the ipsilateral limb. Therefore, clinicians may need to maintain baseline FR magnitudes in the untrained limb when a patient exhibits unilateral KOA characteristics or lateral compartment KOA.

Lateral wedges with and without custom arch support for people with medial knee osteoarthritis and pronated feet: an exploratory randomized crossover study

BACKGROUND

Pronated foot posture is associated with many clinical and biomechanical outcomes unique to medial compartment knee osteoarthritis (OA). Though shoe-worn insole treatment, including lateral wedges, is commonly studied in this patient population, their effects on the specific subgroup of people with medial knee OA and concomitant pronated feet are unknown. The purpose of this study was to evaluate whether lateral wedge insoles with custom arch support are more beneficial than lateral wedge insoles alone for knee and foot symptoms in people with medial tibiofemoral knee osteoarthritis (OA) and pronated feet.

METHODS

Twenty-six people with pronated feet and symptomatic medial knee OA participated in a randomized crossover study comparing five degree lateral wedge foot insoles with and without custom foot arch support. Each intervention was worn for two months, separated by a two-month washout period of no insoles wear. Main outcomes included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and physical function subscales, the revised short-form Foot Function Index (FFI-R) pain and stiffness subscales, and the timed stair climb test. Regression modeling was conducted to examine treatment, period, and interaction effects.

RESULTS

Twenty-two participants completed the study, and no carryover or interaction effects were observed for any outcome. Significant treatment effects were observed for the timed stair climb, with greater improvements seen with the lateral wedges with arch support. Within-condition significant improvements were observed for WOMAC pain and physical function, as well as FFI-R pain and stiffness with lateral wedges with arch support use. More adverse effects were reported with the lateral wedges alone, while more people preferred the lateral wedges with arch support overall.

CONCLUSIONS

Addition of custom arch support to a standard lateral wedge insole may improve foot and knee symptoms in people with knee OA and concomitant pronated feet. These preliminary findings suggest further research evaluating the role of shoe-worn insoles for treatment of this specific sub-group of people with knee OA is warranted.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02234895.

Trunk and lower limb biomechanics during stair climbing in people with and without symptomatic femoroacetabular impingement

BACKGROUND

Femoroacetabular impingement is a pathomechanical hip condition leading to pain and impaired physical function. It has been shown that those with femoroacetabular impingement exhibit altered gait characteristics during level walking and stair climbing, and decreased muscle force production during isometric muscle contractions. However, no studies to-date have looked at trunk kinematics or muscle activation during dynamic movements such as stair climbing in this patient population. The purpose of this study was to compare biomechanical outcomes (trunk and lower limb kinematics as well as lower limb kinetics and muscle activation) during stair climbing in those with and without symptomatic femoroacetabular impingement.

METHODS

Trunk, hip, knee and ankle kinematics, as well as hip, knee and ankle kinetics and muscle activity of nine lower limb muscles were collected during stair climbing for 20 people with clinical and radiographic femoroacetabular impingement and compared to 20 age- and sex-matched pain-free individuals.

FINDINGS

Those with femoroacetabular impingement ascended the stairs slower (effect size=0.82), had significantly increased peak trunk forward flexion angles (effect size=0.99) and external hip flexion moments (effect size=0.94) and had decreased peak external knee flexion moments (effect size=0.90) compared to the control group.

INTERPRETATION

Findings from this study indicate that while those with and without femoroacetabular impingement exhibit many biomechanical similarities when ascending stairs, differences in trunk forward flexion and joint kinetics indicate some important differences. Further longitudinal research is required to elucidate the cause of these differences as well as the clinical relevance.

Knee and ankle biomechanics with lateral wedges with and without a custom arch support in those with medial knee osteoarthritis and flat feet

This study compared immediate changes in knee and ankle/subtalar biomechanics with lateral wedge orthotics with and without custom arch support in people with knee osteoarthritis and flat feet. Twenty-six participants with radiographic evidence of medial knee osteoarthritis (22 females; age 64.0 years [SD 8.0 years], BMI 27.2 kg/m(2) [4.2]) and flat feet (median foot posture index = + 5) underwent three-dimensional gait analysis for three conditions: Control (no orthotic), lateral wedge, and lateral wedge plus arch support. Condition order was randomized. Outcomes included frontal plane knee and ankle/subtalar biomechanics, and comfort. Compared to the control, lateral wedge and lateral wedge with arch support reduced the knee adduction moment impulse by 8% and 6%, respectively (p < 0.05). However, the lateral wedge resulted in a more everted foot position (4.3 degrees) than lateral wedge plus arch support (3.2 degrees) (p < 0.05). In contrast, lateral wedge plus arch support reduced foot frontal plane excursion compared to other conditions (p < 0.05). Participants self-reported significantly more immediate comfort with lateral wedge plus arch support compared to the control, whereas there was no difference in self-reported comfort between lateral wedge and control. No immediate changes in knee pain were observed in any condition.

CLINICAL SIGNIFICANCE

Rather than prescribing lateral wedges to all patients with knee osteoarthritis, those who have medial knee osteoarthritis and flat feet may prefer to use the combined orthotic to reduce loads across the knee, and to minimize the risk of foot and ankle symptoms as a consequence of orthotic treatment. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1597-1605, 2016.

Relationship between knee adduction moment patterns extracted using principal component analysis and discrete measures with different amplitude normalizations: Implications for knee osteoarthritis progression studies

BACKGROUND

Knee adduction moment discrete features (peaks and impulses) are commonly reported in knee osteoarthritis gait studies, but they do not necessarily capture loading patterns. Principal component analysis extracts dynamic patterns, but can be difficult to interpret. This methodological study determined relationships between external knee adduction moment discrete measures and principal component analysis features, and examined whether amplitude-normalization methods influenced differences in those with knee osteoarthritis who progressed to surgery versus those that did not.

METHODS

54 knee osteoarthritis patients had three-dimensional biomechanical measures assessed during walking. Knee adduction moments were calculated and non-normalized and amplitude-normalized waveforms using two common methods were calculated. Patterns were extracted using principal component analysis. Knee adduction moment peak and impulse were calculated. Correlation coefficients were determined between two knee adduction moment patterns extracted and peak and impulse. T-tests evaluated between-group differences.

FINDINGS

An overall magnitude pattern was correlated with peak (r=0.88-0.90, p<0.05) and impulse (r=0.93, p<0.05). A pattern capturing a difference between early and mid/late -stance knee adduction moment was significantly correlated with peak (r=0.27-0.40, p<0.05), but explained minimal variance. Between-group peak differences were only affected by amplitude-normalization method.

INTERPRETATION

Findings suggest that the overall magnitude knee adduction moment principal pattern does not provide unique information from peak and impulse measures. However, low correlations and minimal variance explained between the pattern capturing ability to unload the joint during mid-stance and the two discrete measures, suggests that this pattern captured a unique waveform feature.

Three-dimensional biomechanical gait characteristics at baseline are associated with progression to total knee arthroplasty

Objective

To determine if baseline 3-dimensional (3-D) biomechanical gait patterns differed between those patients with moderate knee osteoarthritis (OA) who progressed to total knee arthroplasty (TKA) and those that did not, and whether these differences had predictive value.

Methods

Fifty-four patients with knee OA had ground reaction forces and segment motions collected during gait. 3-D hip, knee, and ankle angles and moments were calculated over the gait cycle. Amplitude and temporal waveform characteristics were determined using principal component analysis. At followup 5–8 years later, 26 patients reported undergoing TKA. Unpaired t-tests were performed on baseline demographic and waveform characteristics between TKA and no-TKA groups. Receiver operating curve analysis, stepwise discriminate analysis, and logistic regression analysis determined the combination of features that best classified TKA and no-TKA groups and their predictive ability.

Results

Baseline demographic, symptomatic, and radiographic variables were similar, but 7 gait variables differed (P < 0.05) between groups. A multivariate model including overall knee adduction moment magnitude, knee flexion/extension moment difference, and stance–dorsiflexion moment had a 74% correct classification rate, with no overtraining based on cross-validation. A 1-unit increase in model score increased by 6-fold the odds of progression to TKA.

Conclusion

In addition to the link between higher overall knee adduction magnitude and future TKA, an outcome of clear clinical importance, novel findings include altered sagittal plane moment patterns indicative of reduced ability to unload the joint during midstance. This combination of dynamic biomechanical factors had a 6-fold increased odds of future TKA; adding baseline demographic and clinical factors did not improve the model.

The effect of total knee arthroplasty on knee joint kinematics and kinetics during gait

This study determined how total knee arthroplasty (TKA) altered knee motion and loading during gait. Three-dimensional kinematic and kinetic gait patterns of 42 patients with severe knee osteoarthritis were collected 1 week prior and 1-year post-TKA. Principal component analysis extracted major patterns of variability in the gait waveforms. Overall and midstance knee adduction moment magnitude decreased. Overall knee flexion angle magnitude increased due to an increase during swing. Increases in the early stance knee flexion moment and late stance knee extension moment were found, indicating improved impact attenuation and function. A decrease in the early stance knee external rotation moment indicated alteration in the typical rotation mechanism. Most changes moved toward an asymptomatic pattern and would be considered improvements in motion, function, and loading.

Alterations in neuromuscular patterns between pre and one-year post-total knee arthroplasty

BACKGROUND

Total knee arthroplasty is a common treatment for severe knee osteoarthritis. Objective measures are needed to evaluate the effect of arthroplasty surgery on function and joint loading, in particular given the rise in younger adults receiving this intervention. The objective was to compare neuromuscular activation patterns of the knee musculature during level walking one-week prior to and one-year following total knee arthroplasty.

METHODS

Surface electromyograms from seven periarticular muscles were recorded from 43 patients with severe medial compartment knee osteoarthritis during walking one-week prior to and one-year following total knee arthroplasty. Principal component analysis extracted patterns from the electromyographic waveforms and assigned scores for these patterns, which were statistically compared between test times and between medial and lateral sites within a muscle group.

FINDINGS

Significantly lower overall activation amplitudes were found for the quadriceps and hamstrings, with decreased activity during mid-late stance following surgery. Significant increases in gastrocnemius activity were found late stance, along with altered waveform shapes.

INTERPRETATION

In general, the post-surgical changes moved toward more typical asymptomatic patterns, supporting improved neuromuscular strategies during walking. Given that improvements would not be expected to occur naturally in severe osteoarthritic knees the positive changes in neuromuscular characteristics during specific phases of the gait cycle can be explained in part by the altered mechanical environment and reduction in pain from the surgical intervention. These objective findings are directly relevant to the joint loading environment and can be valuable for evaluating surgical techniques, different prostheses and pre-post surgical management.

Temporal coactivation of abdominal muscles during dynamic stability exercises

The purpose of this study was to determine abdominal muscle temporal responses to a leg-loading exercise protocol and if differences exist between those able and unable to minimize lumbar-pelvic motion during this protocol. The focus was a supine bilateral leg-loading task that incorporated a slide (level 4) or no slide (level 5). Thirty-three healthy subjects (mean age 24 years) completed the task while surface electromyograms (EMG) from 5 abdominal muscle sites were recorded. Subjects were assigned to stable or unstable groups based on their ability to minimize lumbar-pelvic motion. After time and amplitude normalization, electromyography waveforms were entered into a pattern recognition procedure and scores for each principal pattern were calculated. Four principal patterns explained 90% of variance in the waveform data, with these principal patterns capturing the mean pattern, the relative amplitude change during the leg-extension phase, and subtle changes in shape throughout the exercise. Significant interactions (p < 0.05) were found for principal patterns; 1, 2, and 4 scores; and significant main (p < 0.05) effects for principal pattern 3 scores. These results illustrate temporal synchrony among the abdominal wall muscle activation during the bilateral leg-loading tasks; however, there was less variability in the activation patterns during the leg-lift and leg extension-phases for those who were able to minimize lumbar-pelvic motion compared to those who were unable to perform the task correctly. These results illustrate the need to focus on coordinated recruiting of the abdominal wall muscles in an organized manner and not simply increasing the intensity of activation for stabilization training.

Polypyrroles as Antioxidants: Kinetic Studies on Reactions of Bilirubin and Biliverdin Dimethyl Esters and Synthetic Model Compounds with Peroxyl Radicals in Solution. Chemical Calculations on Selected Typical Structures

[reaction: see text] Rate constants for hydrogen-atom transfer (HAT) from bilirubin dimethyl ester (BRDE) and biliverdin dimethyl ester (BVDE) to peroxyl radicals during inhibited autoxidation of styrene initiated by azo-bisisobutyronitrile (AIBN) were k(inh)(BRDE) = 22.5 x 10(4) and k(inh)(BVDE) = 10.2 x 10(4) M(-1) s(-1), and the stoichiometric factors (n) were 2.0 and 2.7, respectively. A synthetic tetrapyrrole (bis(dipyrromethene)) containing the alpha-central (2,2') CH2 linkage gave k(inh) = 39.9 x 10(4) M(-1) s(-1) and n = 2.3, whereas the beta-linked (3,3') isomer was not an active antioxidant. Several dipyrrinones were synthesized as mimics of the two outer heterocyclic rings of bilirubin and biliverdin. The dipyrrinones containing N-H groups in each ring were active antioxidants, whereas those lacking two such "free" N-H groups, such as N-CH3 dipyrrinones and dipyrromethenes, did not exhibit antioxidant activity. Overall, the relative k(inh) values compared to those of phenolic antioxidants, 2,6-di-tert-butyl-4-methoxyphenol (DBHA) and 2,6-di-tert-butyl-4-methylphenol (BHT), were 2,2'-bis(dipyrromethene) > BRDE > DBHA > dipyrrinones > BVDE > BHT. This general trend in antioxidant activities was also observed for the inhibited autoxidation of cumene initiated by AIBN. Chemical calculations of the N-H bond dissociation enthalpies (BDEs) of the typical structures support a HAT mechanism from N-H groups to trap peroxyl radicals. Intramolecular hydrogen bonding of intermediate nitrogen radicals has a major influence on the antioxidant activities of all compounds studied. Indeed, chemical calculations showed that the initial nitrogen radical from a dipyrrinone is stabilized by 9.0 kcal/mol because of H-bonding between the N-H remaining on one ring and the ground-state pyrrolyl radical of the adjacent ring in the natural zusammen structure. The calculated minimum structure of bilirubin shows strong intramolecular H-bonding of the N-H groups with carbonyl groups resulting in the known "ridge-tile" structure which is not an active HAT antioxidant. The calculated minimum structure of biliverdin is planar. BRDE is readily converted into BVDE by reaction with the electron-deficient DPPH* radical under argon in chlorobenzene. An electron-transfer mechanism is proposed for the initiating step in this reaction, and this is supported by the relatively low ionizing potential of a model dipyrrole representing the two central rings of bilirubin.

Bilirubin as an Antioxidant: Kinetic Studies of the Reaction of Bilirubin with Peroxyl Radicals in Solution, Micelles, and Lipid Bilayers

Bilirubin (BR) showed very weak antioxidant activity in a nonpolar medium of styrene or cumene in chlorobenzene. In contrast, BR exhibited strong antioxidant activity in polar media such as aqueous lipid bilayers or SDS micelles/methyl linoleate (pH 7.4), where the rate with peroxyl radicals, k(inh) = 5.0 x 10(4) M(-)(1) s(-)(1), was comparable to that with vitamin E analogues, Trolox, or PMHC. An electron-transfer mechanism accounts for the effect of the medium on the antioxidant properties of BR.