Neither total muscle activation nor co-activation explains the youthful walking economy of older runners

Publication date: Available online 20 July 2018

Source: Gait & Posture

Author(s): Owen N. Beck, Alena M. Grabowski, Justus D. Ortega

Abstract

Background

Older adults (≥65 years) exhibited greater metabolic rates during walking (worse walking economy) compared to young adults. Yet, previous research suggests that habitual running, but not habitual walking, exercise mitigates the age-related deterioration of walking economy.

Research Question

Does total leg muscle activation and/or agonist-antagonist co-activation explain the superior walking economy of older runners versus older walkers? Methods: We quantified metabolic power, leg muscle activation, and co-activation in older walkers and older runners during walking at 0.75, 1.25, and 1.75 m/s.

Results

Neither total stride (each speed p ≥ 0.024), stance- (each speed p ≥ 0.217), nor swing- (each speed p ≥ 0.170) phase EMG amplitude differed between older walkers and older runners at 0.75, 1.25, or 1.75 m/s. Stride averaged medial gastrocnemius and biceps femoris activation were less in older runners than older walkers at 1.25 and 1.75 m/s (all p ≤ 0.025). We also calculated shank, thigh, and overall (shank and thigh) agonist-antagonist leg muscle co-activation over each stride phase and the only difference between groups was a greater shank co-activation in older runners at 0.75 m/s (p = 0.024). Across groups, stride, stance-, and swing-phase total muscle activation positively correlated with gross metabolic power (R² = 0.58-0.66; all p < 0.001). Paradoxically, across groups, stride, stance-, and swing-phase muscle co-activation indices were negatively correlated with gross metabolic power (R² = 0.08-0.29; all p ≤ 0.007).

Significance

Neither total leg muscle activation nor co-activation explains the superior walking economy of older runners versus older walkers.

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Neither total muscle activation nor co-activation explains the youthful walking economy of older runners

Publication date: Available online 20 July 2018

Source: Gait & Posture

Author(s): Owen N. Beck, Alena M. Grabowski, Justus D. Ortega

Abstract

Background

Older adults (≥65 years) exhibited greater metabolic rates during walking (worse walking economy) compared to young adults. Yet, previous research suggests that habitual running, but not habitual walking, exercise mitigates the age-related deterioration of walking economy.

Research Question

Does total leg muscle activation and/or agonist-antagonist co-activation explain the superior walking economy of older runners versus older walkers? Methods: We quantified metabolic power, leg muscle activation, and co-activation in older walkers and older runners during walking at 0.75, 1.25, and 1.75 m/s.

Results

Neither total stride (each speed p ≥ 0.024), stance- (each speed p ≥ 0.217), nor swing- (each speed p ≥ 0.170) phase EMG amplitude differed between older walkers and older runners at 0.75, 1.25, or 1.75 m/s. Stride averaged medial gastrocnemius and biceps femoris activation were less in older runners than older walkers at 1.25 and 1.75 m/s (all p ≤ 0.025). We also calculated shank, thigh, and overall (shank and thigh) agonist-antagonist leg muscle co-activation over each stride phase and the only difference between groups was a greater shank co-activation in older runners at 0.75 m/s (p = 0.024). Across groups, stride, stance-, and swing-phase total muscle activation positively correlated with gross metabolic power (R² = 0.58-0.66; all p < 0.001). Paradoxically, across groups, stride, stance-, and swing-phase muscle co-activation indices were negatively correlated with gross metabolic power (R² = 0.08-0.29; all p ≤ 0.007).

Significance

Neither total leg muscle activation nor co-activation explains the superior walking economy of older runners versus older walkers.

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Pregnancy walking cadence does not vary by trimester

Publication date: September 2018

Source: Gait & Posture, Volume 65

Author(s): Mallory R. Marshall, Alexander H.K. Montoye, Ashley J. George

Abstract

Background

Pregnancy-related changes in walking speed, gait dynamics, and total physical activity have been reported in past research, but free-living step cadences and their rates of change across pregnancy have not been studied.

Research question

The purpose of this study was to describe free-living stepping cadence in pregnant women and examine differences between second and third trimester women. We hypothesized that physical activity walking cadences would be lower later in pregnancy.

Methods

Fifty pregnant women were recruited for this study and n = 45 was the analytic sample size; 46.7% were in their second trimester (13–25 weeks) while 53.3% were third trimester (≥26 weeks). Participants completed a survey of demographic characteristics and wore an accelerometer on their non-dominant wrist for 7–8 days. These accelerometer data were downloaded in 60-sec epochs, allowing for determination of min-by-min walking cadence, defined as steps/min. Mean steps/day, mean cadence, peak cadence (average cadence over the 30 min of highest cadence in each day), mean time spent in moderate- to vigorous-intensity physical activity (MVPA, time spent with cadence ≥100 steps/min), and mean daily time spent in several cadence ranges were calculated for each participant. Between-trimester differences were determined using independent-samples t-tests.

Results

Average daily steps were 11,060.1 ± 2,955.3; 66.7% of second trimester and 54.2% of third trimester women met daily step recommendations of 10,000 steps/day, but 0.0% of the sample accumulated the recommended 150 min/wk of MVPA. There were no differences by trimester for cadence at any step rates (p > 0.05).

Significance

Overall, pregnant women accumulated high numbers of steps per day but at low cadences; neither daily steps nor cadence varied from second to third trimester. These data suggest that steps and MVPA recommendations are not equivalent and therefore should not be used interchangeably, especially during pregnancy.

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Late-cueing of gait tasks on an uneven brick surface impacts coordination and center of mass control in older adults

Publication date: Available online 19 July 2018

Source: Gait & Posture

Author(s): Philippe C. Dixon, Jesse V. Jacobs, Jack T. Dennerlein, Jeffrey M. Schiffman

Abstract

Background

Changing directions while walking (turning gait), often with little planning time, is essential to navigate irregular surfaces in the built-environment. It is unclear how older adults reorient their bodies under these constraints and whether adaptations are related to declines in physiological characteristics.

Research question

The aims of this study were to (1) investigate whether surface irregularity, late-cueing, and age negatively affect coordination, kinematics, and center of mass (COM) movement during 90º turning gait and (2) determine if adaptations correlate with declines in strength, balance, and reaction-time.

Methods

Eighteen young (18-35 years) and sixteen older (65+ years) healthy adults participated in the study. Retro-reflective marker and trunk-accelerometry data were used to compute upper-body segmental reorientation timing, upper-body kinematics, and COM movement characteristics. Balance scores, lower-limb strength, and choice-reaction-times were also recorded.

Results

Young and older adults maintained a cranial-caudal (head, shoulders, pelvis) reorientation sequence (p ≤ 0.018), lowered head pitch (uneven surface; young p = 0.035 and old p < 0.001), increased maximum COM acceleration (uneven surface and late-cueing; p ≤ 0.002), and decreased COM smoothness (uneven surface; p < 0.001). Young adults increased shoulder roll (uneven surface and late-cueing; p ≤ 0.008). Reduced stride regularity (late-cueing) was observed in older (p < 0.001), compared to young (p = 0.017), adults. Declines in strength (p ≤ 0.040) and balance (p = 0.018) were correlated with gait adaptations of older adults.

Significance

Late-cueing on an uneven surface is challenging for older adults. These challenges are exacerbated by strength and balance deficits.

Graphical abstract

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Dynamic Visual Acuity test while walking or running on treadmill: reliability and normative data

Publication date: Available online 19 July 2018

Source: Gait & Posture

Author(s): Evi Verbecque, Tamaya Van Criekinge, Delphine Vanloot, Tanja Coeckelbergh, Paul Van de Heyning, Ann Hallemans, Luc Vereeck

Abstract

Background

This study aimed to report normative reference data for a Dynamic Visual Acuity test while walking on treadmill. The protocol’s suitability was assessed by investigating its test-retest reliability and its validity through the drop-out rate and verification of the frequency of head movements. Furthermore, the influence of age on visual acuity loss (VAL) was determined to reveal the need for age-specific reference data.

Methods

Visual acuity was measured in 171 healthy adult participants (age range: 20.0-77.3 years; mean age: 40.1 years) with the head stationary (SVA) and in a dynamic condition (DVA) while walking on treadmill at 3, 4, 6 and 9 km/h. Relative test-retest reliability on SVA and DVA was investigated with intraclass correlation coefficients (ICC). The measurement errors of SVA, DVA and VAL were calculated for absolute reliability. Influence of age on VAL was investigated with regression analysis, followed by an ANOVA to investigate decade-related differences. The drop-out rate during DVA was mapped using a frequency table. Head frequencies were monitored using 3D motion tracking software.

Results

Strong consistency (ICC ≥ 0.89) was found for SVA and DVA values. Measurement errors for VAL were less than 0.1 logMAR. Younger participants (decade 3-4) showed less VAL at 3 and 4 km/h. The drop-out rate increased with increasing walking speed (0-18.8%), especially in older adults. Although head frequency increased with increasing speed, the dominant frequency ranged around 2 Hz for all walking speeds.

Conclusion

This DVA protocol is reliable and normative data have been established. To facilitate its use in clinical practice, further validation of the protocol in patients with bilateral vestibulopathy is needed.

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Objective measures of gait and balance in healthy non-falling adults as a function of age

Publication date: Available online 19 July 2018

Source: Gait & Posture

Author(s): Tuhin Virmani, Harsh Gupta, Jesal Shah, Linda Larson-Prior

ABSTRACT

BACKGROUND

Neurodegenerative diseases increase in incidence with age. Prior studies using differing populations and gait paradigms have reported various parameters changing with age, some of which correlate with falls and mortality. Here we use three different paradigms to evaluate gait and balance in healthy non-fallers.

RESEARCH QUESTION

What objective gait and balance parameters are correlated with aging.

METHODS

Healthy subjects aged 21-79 years without histories of falls, lower extremity orthopedic procedures or chronic pain were included. Subjects walked on a 20 × 4 foot pressure sensor mat (Zeno Walkway, Protokinetics, Havertown, PA) under three different gait paradigms, (i) steady-state gait, (ii) dual-task while texting on a cellular phone and (iii) tandem gait. Data was collected and analyzed using PKMAS software (Protokinetics). Linear regression analysis, stepwise multivariate analysis, and grouped analysis of gait parameters was performed using SPSS 22 (IBM).

RESULTS

Seventy-five subjects were enrolled. Grouped analysis and linear regression analysis showed differing significance in parameters tested. Step-wise multivariate analysis of all 31 parameters assessed from three different gait paradigms, showed weak but significant correlations in age with (i) stride-to-stride variability in (i) integrated-pressure of footsteps and (ii) stride-length during steady-state gait, (iii) mean stride-length on dual-task, and (iv) mean step-width on tandem gait (R² = 0.382, t = 2.26, p = 0.026).

SIGNIFICANCE

In a population of healthy subjects without prior history of falls or medical illness that should affect gait, there were weak but significant age-related changes in objective measures of steady state gait and balance. Future prospective longitudinal data will help predict the relevance of this in relation to falls in the elderly.

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Pregnancy walking cadence does not vary by trimester

Publication date: September 2018

Source: Gait & Posture, Volume 65

Author(s): Mallory R. Marshall, Alexander H.K. Montoye, Ashley J. George

Abstract

Background

Pregnancy-related changes in walking speed, gait dynamics, and total physical activity have been reported in past research, but free-living step cadences and their rates of change across pregnancy have not been studied.

Research question

The purpose of this study was to describe free-living stepping cadence in pregnant women and examine differences between second and third trimester women. We hypothesized that physical activity walking cadences would be lower later in pregnancy.

Methods

Fifty pregnant women were recruited for this study and n = 45 was the analytic sample size; 46.7% were in their second trimester (13–25 weeks) while 53.3% were third trimester (≥26 weeks). Participants completed a survey of demographic characteristics and wore an accelerometer on their non-dominant wrist for 7–8 days. These accelerometer data were downloaded in 60-sec epochs, allowing for determination of min-by-min walking cadence, defined as steps/min. Mean steps/day, mean cadence, peak cadence (average cadence over the 30 min of highest cadence in each day), mean time spent in moderate- to vigorous-intensity physical activity (MVPA, time spent with cadence ≥100 steps/min), and mean daily time spent in several cadence ranges were calculated for each participant. Between-trimester differences were determined using independent-samples t-tests.

Results

Average daily steps were 11,060.1 ± 2,955.3; 66.7% of second trimester and 54.2% of third trimester women met daily step recommendations of 10,000 steps/day, but 0.0% of the sample accumulated the recommended 150 min/wk of MVPA. There were no differences by trimester for cadence at any step rates (p > 0.05).

Significance

Overall, pregnant women accumulated high numbers of steps per day but at low cadences; neither daily steps nor cadence varied from second to third trimester. These data suggest that steps and MVPA recommendations are not equivalent and therefore should not be used interchangeably, especially during pregnancy.

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