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Rebecca L. Krupenevich and Ross H. Miller

plantar flexion angle at push off, 5 , 6 resulting in a shorter ground reaction force moment arm 7 and a smaller peak ankle joint moment. Indeed, step length is a strong correlate of ankle joint kinetics in young and older adults. 6 Moreover, modifying step lengths in young adults has been shown to

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Tiago M. Barbosa, Kelly de Jesus, J. Arturo Abraldes, João Ribeiro, Pedro Figueiredo, João Paulo Vilas-Boas and Ricardo J. Fernandes

Background:

The assessment of energetic and mechanical parameters in swimming often requires the use of an intermittent incremental protocol, whose step lengths are corner stones for the efficiency of the evaluation procedures.

Purpose:

To analyze changes in swimming kinematics and interlimb coordination behavior in 3 variants, with different step lengths, of an intermittent incremental protocol.

Methods:

Twenty-two male swimmers performed n × d i variants of an intermittent and incremental protocol (n ≤ 7; d 1 = 200 m, d 2 = 300 m, and d 3 = 400 m). Swimmers were videotaped in the sagittal plane for 2-dimensional kinematical analysis using a dualmedia setup. Video images were digitized with a motion-capture system. Parameters that were assessed included the stroke kinematics, the segmental and anatomical landmark kinematics, and interlimb coordination. Movement efficiency was also estimated.

Results:

There were no significant variations in any of the selected variables according to the step lengths. A high to very high relationship was observed between step lengths. The bias was much reduced and the 95%CI fairly tight.

Conclusions:

Since there were no meaningful differences between the 3 protocol variants, the 1 with shortest step length (ie, 200 m) should be adopted for logistical reasons.

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Guneet Chawla, Madelon Hoppe, Nina Browner and Michael D. Lewek

via manipulation of cadence may not initiate the necessary changes in step length ( Hoppe, Chawla, Browner, & Lewek, 2020 ). This is particularly important because individuals with PD exhibit substantial deficits in spatial measures (e.g., step length; Morris, Iansek, Matyas, & Summers, 1994 ), yet

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Jasper Reenalda, Maurice T.F. Maas and Jos J. de Koning

Purpose:

To examine the influence of induced changes in the morphology of the leg by adding mass on the optimal step length (OSL) in experienced runners to get more insight into parameters that influence preferred step length (PSL) and OSL.

Methods:

Thirteen experienced male runners (mean age 26.9 ± 6.1 y, height 183.7 ± 7.1 cm, mass 71.8 ± 5.9 kg) ran on a treadmill in 3 different conditions: unloaded (UL), loaded with 2 kg mass at the ankles (MA), and loaded with 2 kg mass at the hips (MH) at 7 different step lengths (SLs). SL deviations were expressed as deviations in relative leg length (%LL) from the individual PSL: 0%LL, ±5%LL, ±10%LL, and ±15%LL. Trials lasted 8 min, and 8 min of rest was given between trials. Oxygen uptake (V̇O2) was expressed as a fraction of V̇O2 at PSL + 0%LL in the unloaded condition (%V̇O2). The %SL with the lowest value of %V̇O2 was considered the OSL for this group of participants.

Results:

OSL at the UL condition was 6% shorter than PSL. The MA condition resulted in a 7%LL larger OSL than at UL and MH (P < .05).

Conclusions:

The mass distribution of the leg is a determinant of the OSL. As a consequence of the added mass to the ankles, OSL was 7%LL longer. Morphological characteristics of the leg might therefore play an important role in determining the runner’s individual optimal SL.

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Dennis E. Anderson, Christopher T. Franck and Michael L. Madigan

The effects of gait speed and step length on the required coefficient of friction (COF) confound the investigation of age-related differences in required COF. The goals of this study were to investigate whether age differences in required COF during self-selected gait persist when experimentally-controlling speed and step length, and to determine the independent effects of speed and step length on required COF. Ten young and 10 older healthy adults performed gait trials under five gait conditions: self-selected, slow and fast speeds without controlling step length, and slow and fast speeds while controlling step length. During self-selected gait, older adults walked with shorter step lengths and exhibited a lower required COF. Older adults also exhibited a lower required COF when walking at a controlled speed without controlling step length. When both age groups walked with the same speed and step length, no age difference in required COF was found. Thus, speed and step length can have a large influence on studies investigating age-related differences in required COF. It was also found that speed and step length have independent and opposite effects on required COF, with step length having a strong positive effect on required COF, and speed having a weaker negative effect.

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Shanelle Sorbello, Vu Quang Do, Anna Palagyi and Lisa Keay

step length. All vision categories are according to better eye: nil (VA ≤ 0.3 logMAR), mild (0.3 < VA ≤ 0.5 logMAR), moderate (0.5 < VA ≤ 1.00), and severe (VA > 1.00 logMAR). Bars indicate Q3, median, and Q1 values, respectively; and whiskers indicate maximum/minimum values for each group. Note . SB

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Kim T.J. Bongers, Yvonne Schoon, Maartje J. Graauwmans, Marlies E. Hoogsteen-Ossewaarde and Marcel G.M. Olde Rikkert

Self-management of mobility and fall risk might be possible if older adults could use a simple and safe self-test to measure their own mobility, balance, and fall risk at home. The aim of this study was to determine the safety, feasibility, and intraindividual reliability of the maximal step length (MSL), gait speed (GS), and chair test (CT) as potential self-tests for assessing mobility and fall risk. Fifty-six community-dwelling older adults performed MSL, GS, and CT at home once a week during a four-week period, wherein the feasibility, test-retest reliability, coefficients of variation, and linear mixed models with random effects of these three self-tests were determined. Forty-nine subjects (mean age 76.1 years [SD: 4.0], 19 females [42%]) completed the study without adverse effects. Compared with the other self-tests, MSL gave the most often (77.6%) valid measurement results and had the best intraclass correlation coefficients (0.95 [95% confidence interval: 0.91−0.97]). MSL and GS gave no significant training effect, whereas CT did show a significant training effect (p < .01). Community-dwelling older adults can perform MSL safely, correctly, and reliably, and GS safely and reliably. Further research is needed to study the responsiveness and beneficial effects of these self-tests on self-management of mobility and fall risk.

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Hiroaki Hobara, Wolfgang Potthast, Ralf Müller, Yoshiyuki Kobayashi, Thijs A. Heldoorn and Masaaki Mochimaru

The aim of this study was to develop a normative sample of step frequency and step length during maximal sprinting in amputee sprinters. We analyzed elite-level 100-m races of 255 amputees and 93 able-bodied sprinters, both men and women, from publicly-available Internet broadcasts. For each sprinter’s run, the average forward velocity, step frequency, and step length over the 100-m distance were analyzed by using the official record and number of steps in each race. The average forward velocity was greatest in able-bodied sprinters (10.04 ± 0.17 m/s), followed by bilateral transtibial (8.77 ± 0.27 m/s), unilateral transtibial (8.65 ± 0.30 m/s), and transfemoral amputee sprinters (7.65 ± 0.38 m/s) in men. Differences in velocity among 4 groups were associated with step length (able-bodied vs transtibial amputees) or both step frequency and step length (able-bodied vs transfemoral amputees). Although we also found that the velocity was greatest in able-bodied sprinters (9.10 ± 0.14 m/s), followed by unilateral transtibial (7.08 ± 0.26 m/s), bilateral transtibial (7.06 ± 0.48 m/s), and transfemoral amputee sprinters (5.92 ± 0.33 m/s) in women, the differences in the velocity among the groups were associated with both step frequency and step length. Current results suggest that spatiotemporal parameters during a 100-m race of amputee sprinters is varied by amputation levels and sex.

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Robert W. Meyers, Jon L. Oliver, Michael G. Hughes, Rhodri S. Lloyd and John Cronin

The purpose of this study was to examine the reliability of the spatiotemporal determinants of maximal sprinting speed in boys over single and multiple steps. Fifty-four adolescent boys (age = 14.1 ± 0.7 years [range = 12.9–15.7 years]; height = 1.63 ± 0.09 m; body mass = 55.3 ± 13.3 kg; -0.31 ± 0.90 age from Peak Height Velocity (PHV) in years; mean ± s) volunteered to complete a 30 m sprint test on 3 occasions over a 2-week period. Speed, step length, step frequency, contact time, and flight time were assessed via an optical measurement system. Speed and step characteristics were obtained from the single-fastest step and average of the 2 and 4 fastest consecutive steps. Pairwise comparison of consecutive trials revealed the coefficient of variation (CV) for speed was greater in 4-step (CV = 7.3 & 7.5%) compared with 2-step (CV = 4.2 & 4.1%) and 1-step (CV = 4.8 & 4.6%) analysis. The CV of step length, step frequency and contact time ranged from 4.8 to 7.5% for 1-step, 3.8–5.0% for 2-step and 4.2–7.5% for 4-step analyses across all trials. An acceptable degree of reliability was achieved for the spatiotemporal and performance variables assessed in this study. Two-step analysis demonstrated the highest degree of reliability for the key spatiotemporal variables, and therefore may be the most suitable approach to monitor the spatiotemporal characteristics of maximal sprint speed in boys.

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Antonio M. López, Diego Álvarez, Rafael C. González and Juan C. Álvarez

Pedometers are basically step counters usually used to estimate the distance walked by a pedestrian. Although their precision to compute the number of steps is quite accurate (about 1%), their feasibility to estimate the walked distance is very poor, as they do not consider the intrinsic variability of human gait. Reported results show values of 10% of precision in optimal conditions, increasing to 50% when conditions differ. Electronic accelerometer-based pedometers base their functioning on a basic processing of the vertical acceleration of the waist. Recently, different approaches have been proposed to relate such signals to the step length. This can lead to an improvement of the performance of this kind of device for estimating the walked distance. In this article, we analyze four gait models applied to the vertical accelerations of the body’s center of gravity, three biomechanical and one empirical. We compare their precision and accuracy. Results support the superior performance of three of them over an ideal pedometer. We also analyze their feasibility to be implemented in pedometer-like devices.