Preferred Cadence Research Articles

The Ramp protocol: Uncovering individual differences in walking to an auditory beat using TeensyStep

Intentionally walking to the beat of an auditory stimulus seems effortless for most humans. However, studies have revealed significant individual differences in the spontaneous tendency to synchronize. Some individuals tend to adapt their walking pace to the beat, while others show little or no adjustment. To fill this gap we introduce the Ramp protocol, which measures spontaneous adaptation to a change in an auditory rhythmic stimulus in a gait task. First, participants walk at their preferred cadence without stimulation. After several steps, a metronome is presented, timed to match the participant’s heel-strike. Then, the metronome tempo progressively departs from the participant’s cadence by either accelerating or decelerating. The implementation of the Ramp protocol required real-time detection of heel-strike and auditory stimuli aligned with participants’ preferred cadence. To achieve this, we developed the TeensyStep device, which we validated compared to a gold standard for step detection. We also demonstrated the sensitivity of the Ramp protocol to individual differences in the spontaneous response to a tempo-changing rhythmic stimulus by introducing a new measure: the Response Score. This new method and quantification of spontaneous response to rhythmic stimuli holds promise for highlighting and distinguishing different profiles of adaptation in a gait task.

Influence of foot strike patterns and cadences on patellofemoral joint stress in male runners with patellofemoral pain

ObjectivesThis study aimed to determine the effect of foot strike patterns and cadences in male runners with patellofemoral pain (PFP). DesignCross-sectional study. SettingBiomechanics lab. Methods20 male runners with PFP were instructed to randomly complete six running conditions (three cadence conditions in rearfoot strike pattern (RFS) or forefoot strike (FFS)) under a preferred running speed. Main outcome measuresThe primary outcomes were peak knee joint and moment, and secondary outcomes were patellofemoral joint stress. ResultsRunning with increased cadence has a lower flexion angle (P = 0.027, η2 = 0.45), lower extension moment (P = 0.011, η2 = 0.29), lower internal rotation moment (P = 0.040, η2 = 0.17), lower patellofemoral stress (P = 0.029, η2 = 0.52) than preferred cadence. FFS running performed significantly lower flexion angle (P = 0.003, η2 = 0.39), lower extension moment (P < 0.001, η2 = 0.91), lower adduction moment (P = 0.020, η2 = 0.25) lower patellofemoral stress (P < 0.001, η2 = 0.81) than RFS running for all cadence. ConclusionsPreliminary findings provide new perspectives for male runners with PFP to unload patellofemoral joint stress in managing PFP through the combination of the FFS pattern and increased cadence.

Preferred temporal-spatial parameters, physical maturation, and sex are related to vertical and braking forces in adolescent long-distance runners

ABSTRACT For adults, increasing cadence reduces ground reaction forces, but a lower preferred cadence does not predispose adults to experience higher ground reaction forces. Pubertal growth and motor control changes influence running mechanics, but it is unknown if preferred cadence or step length are associated with ground reaction forces for pre-adolescent and adolescent runners. Pre-adolescent and adolescent runners underwent an overground running analysis at a self-selected speed. Mixed model multiple linear regressions investigated the associations of preferred cadence, step length, physical maturation, and sex on ground reaction forces, while accounting for running speed and leg length. Running with a lower preferred cadence or longer preferred step length was associated with larger peak braking and vertical forces (p ≤ .01), being less physically mature was associated with larger vertical impact peak force and vertical loading rate (p ≤ .01), and being a male was associated with larger loading rates (p ≤ .01). A lower preferred cadence or longer preferred step length were associated with higher braking and vertical forces and being less physically mature or a male were associated with higher loading rates. An intervention to increase cadence/decrease step length could be considered if ground reaction forces are a concern for an adolescent runner.

Biomechanical Effects of Manipulating Preferred Cadence During Treadmill Walking in Patients With ACL Reconstruction.

Abnormal gait is common after anterior cruciate ligament reconstruction (ACLR) which may influence osteoarthritis risk in this population. Yet few gait retraining options currently exist in ACLR rehabilitation. Cueing cadence changes is a simple, low-cost method that can alter walking mechanics in healthy adults, but few studies have tested its effectiveness in an ACLR population. Here, we evaluated the acute effects of altering cadence on knee mechanics in patients 9 to 12 months post ACLR. Cueing larger steps will facilitate larger knee angles and moments, while cueing smaller steps would induce smaller knee angles and moments. Randomized cross-sectional design. Level 3. Twenty-eight patients with unilateral ACLR underwent gait assessments on a treadmill at preferred pace. Preferred walking gait was assessed first to obtain preferred cadence. Participants then completed trials while matching an audible beat set to 90% and 110% of preferred cadence in a randomized order. Three-dimensional sagittal and frontal plane biomechanics were evaluated bilaterally. Compared with preferred cadence, cueing larger steps induced larger peak knee flexion moments (KFMs) and knee extension excursions bilaterally (P < 0.01), whereas cueing smaller steps only reduced knee flexion excursions (P < 0.01). Knee adduction moments remain unchanged across conditions and were similar between limbs (P > 0.05). Peak KFMs and excursions were smaller in the injured compared with uninjured limb (P < 0.01). Frontal plane gait outcomes were unchanged across conditions suggesting acute cadence manipulations result in mainly sagittal plane adaptations. Follow-up studies using a longitudinal cadence biofeedback paradigm may be warranted to elucidate the utility of this gait retraining strategy after ACLR. Cueing changes in walking cadence can target sagittal plane knee loading and joint range of motion in ACLR participants. This strategy may offer high clinical translatability given it requires relatively minimal equipment (ie, free metronome app) outside of a treadmill.

Walk Smarter, Not Harder: Effects of Cadence Manipulation on Gait Biomechanics in Patients with Patellofemoral Osteoarthritis.

This study aimed to investigate the effect of walking cadence on knee flexion angular impulse and peak external flexion moment in patients with patellofemoral osteoarthritis (OA). Forty-eight patients with patellofemoral OA underwent repeated quantitative gait analyses on an instrumented treadmill using a randomized crossover design. Walking trials were conducted at a fixed gait speed, under three cadence conditions: (i) preferred cadence, (ii) +10% increased cadence, and (iii) -10% decreased cadence, completed in random order. Using a linear mixed model, we tested the association of cadence conditions with surrogate measures of patellofemoral load (primary outcome measure: knee flexion angular impulse) while controlling for body mass. We then repeated the analyses while sequentially replacing the dependent variable with secondary outcome measures. Walking with increased cadence decreased (adjusted mean difference [95% confidence interval]) the knee flexion angular impulse (-0.85 N·m·s -1 [-1.52 to -0.18], d = 0.20) and peak knee flexion moment (-4.11 N·m [-7.35 to -0.86], d = 0.24), whereas walking with decreased cadence increased the knee flexion angular impulse (1.83 N·m·s -1 [1.15 to 2.49], d = 0.42) and peak knee flexion moment (3.55 N·m [0.30 to 6.78], d = 0.21). Similar decreases and increases were observed for secondary outcome measures. Walking with increased cadence, while maintaining a fixed gait speed, reduces knee flexion angular impulse as well as other surrogate measures of knee loading in patients with patellofemoral OA.

Running-style modulation: Effects of stance-time and flight-time instructions on duty factor and cadence

BackgroundThe duty factor (reflecting the ratio of stance to flight time) is an important variable related to running performance, economy, and injury risk. According to the dual-axis model, the duty factor and the cadence are sufficient to describe an individual’s running style at a certain speed. To test this model, one should be able to modulate both variables independently. While acoustic pacing is an established method for cadence modulation, no such method is available for duty-factor modulation. Research questionsCan people modulate their duty factor based on verbal instructions to change either their stance or flight time without changing their cadence? And, if so, which instruction is most effective? MethodsTwelve participants ran on an instrumented treadmill and completed four training blocks starting with a baseline trial and ending with a performance trial in which they followed verbal instructions to both increase and decrease their stance and flight time. Acoustic pacing at their preferred cadence was present during the first part of each trial. We calculated the duty factor and cadence for paced and non-paced parts of each trial, assessed the effectiveness of the instructions aimed at changing the duty factor, and examined the effects of instructions and acoustic pacing on cadence using Bayesian statistics. ResultsThe duty factor changed in intended directions with verbal instructions to increase and decrease the stance and flight time (18.04 ≤ BF10 ≤ 4954.42), without differences between the instructions or during and after acoustic pacing. The instructions and acoustic pacing did not result in a consistent change in cadence (0.40 ≤ BF10 ≤ 2.59). SignificanceRunners can change their duty factor through verbal instructions pertaining to stance or flight time, without clear concomitant effects on cadence. Running styles can thus be altered with verbal instructions to change stance or flight time for duty-factor modulation, optionally combined with acoustic pacing to prescribe cadence.

Powered Knee and Ankle Prosthesis With Adaptive Control Enables Climbing Stairs With Different Stair Heights, Cadences, and Gait Patterns

Powered prostheses can enable individuals with above-knee amputations to ascend stairs step-over-step. To accomplish this task, available stair ascent controllers impose a pre-defined joint impedance behavior or follow a pre-programmed position trajectory. These control approaches have proved successful in the laboratory. However, they are not robust to changes in stair height or cadence, which is essential for real-world ambulation. Here we present an adaptive stair ascent controller that enables individuals with above-knee amputations to climb stairs of varying stair heights at their preferred cadence and with their preferred gait pattern. We found that modulating the prosthesis knee and ankle position as a function of the user's thigh in swing provides toe clearance for varying stair heights. In stance, modulating the torque-angle relationship as a function of the prosthesis knee position at foot contact provides sufficient torque assistance for climbing stairs of different heights. Furthermore, the proposed controller enables individuals to climb stairs at their preferred cadence and gait pattern, such as step-by-step, step-over-step, and two-steps. The proposed adaptive stair controller may improve the robustness of powered prostheses to environmental and human variance, enabling powered prostheses to more easily move from the lab to the real-world.

Using beat frequency in music to adjust running cadence in recreational runners: A randomized multiple baseline design

ABSTRACT Running with music has been shown to acutely change cadence. However, it is unclear if the increased cadence remains long-term when running without music in an in-field situation. The aim of this 12-week study was to investigate the effect of a 4-week music running program on cadence, speed and heartrate during and after the music running program. Seven recreational runners with a cadence of <170 steps per minute were randomly assigned to a baseline and post-intervention period of different durations. During the intervention phase, the participants ran with a musical beat that was 7.5–10% higher than their mean cadence at the start of the study. Cadence, heartrate and running speed were measured twice a week during a 5-kilometer run with a watch, and were analyzed using randomization tests and visual data inspection. Two participants dropped-out due to shortage of time (n = 1) and an acute calf injury (n = 1). Cadence significantly increased during the intervention period (+8.5%), and remained elevated during the post-intervention period (+7.9% (p = .001)) in comparison with the baseline period. Heartrate and running speed did not significantly change during any period. This study among five participants shows that four weeks of running with a musical beat that is 7.5–10% higher than the preferred cadence may be an effective and feasible intervention to increase running cadence. Importantly, the increased cadence occurred without simultaneous increases in running speed and heartrate, hereby potentially reducing mechanical loading without increasing metabolic load. Highlights Running with a musical rhythm that is higher than the preferred cadence leads to an increased running cadence, without increasing heartrate and running speed. This cadence remains elevated for at least three to five weeks after the music intervention period. All individuals showed a practically relevant increase in cadence during and after the intervention.

Modeling cycling performance: Effects of saddle position and cadence on cycle pedaling efficiency.

The modeling method is an effective means of estimating causality as well as examining cycle pedaling efficiency. Pedaling efficiency can also be examined by an experimental method, but the experimental method can lead to contradictory results due to perturbation of the measured output parameters. Experimental studies generally yield realistic results, but it is difficult to control for all the variables of interest and to determine the causal relationships between them. The objective of this study is to investigate the pedaling efficiency and causality with considering saddle position and pedaling cadence as variables. Based on the mathematical pedaling modeling, the internal work calculation method was used to calculate the consumed mechanical energy and energy conservation percentage (). The optimal saddle position with the lowest mechanical energy and the highest energy conservation percentage could be changed by the cadence. At the low cadence, the higher saddle position, and the shorter horizontal distance between the saddle and crankshaft led to higher pedaling efficiency (h: 0.95 m, d: 0.16 m, and knee angle: ). However, the highest pedaling efficiency was achieved at the high cadence with a saddle height (h) of 0.9 m and a horizontal distance between the saddle and the crankshaft (d) of 0.06 m (knee angle: ). The lowest cadence is the optimal cadence in terms of the consumed energy, but the optimal cadence was 90 r/min in terms of the energy conservation percentage. Compared to the energy consumption, the energy conservation percentage was demonstrated to influence the fatigue of a cycle rider more critically. The energy conservation percentage was highest at 90 r/min, and 90 r/min was close to the preferred cadence by the cyclist.

Effect of Increasing Running Cadence on Peak Impact Force in an Outdoor Environment.

BackgroundAn estimated 56% of recreational runners sustain a running-related injury related to the high impact forces in running. Increasing step frequency (cadence) while maintaining a consistent speed has been shown to be an effective way to lower impact forces which may reduce injury risk.PurposeTo examine effects of increased cadence on peak impact force during running in an outdoor setting. It was hypothesized that as cadence increases, peak force would decrease.Study DesignRepeated measures, quasi-experimentalMethodsPeak force and cadence measurements were collected from 15 recreational runners (8 females, 7 males) during two 2.4-mile outdoor runs. Peak force was measured using an insole-based load measuring device. Baseline session run was completed at participant’s naturally preferred cadence and cadence session run was completed at a cadence targeted to be 10% greater than baseline. Pace was monitored with a GPS watch. Cadence was cued by an auditory metronome and measured with both GPS watch and insoles. Repeated-measures ANOVA’s examined the differences in average peak force, GPS-reported cadence, and insole-reported cadence between mile 1 and mile 2, and across the two cadence conditions.ResultsCadence differences of 7.3% were observed between baseline and cadence sessions (p<0.001). A concurrent decrease in average peak force of 5.6% was demonstrated during the cadence run (p<0.05). Average cadences measured by GPS watch and insoles were found to be the same at both baseline (p=0.096) and during cadence (p=0.352) sessions.ConclusionIncreasing cadence by an average of 7% in an outdoor setting resulted in a decrease in peak force at two different time points during a 2.4-mile run. Furthermore, using a metronome for in-field cadence manipulation led to a change in cadence. This suggests that a metronome may be an effective tool to manipulate cadence for the purpose of decreasing peak impact force in an outdoor setting.Level of evidence3b

Using Cadence to Predict the Walk-to-Run Transition in Children and Adolescents: A Logistic Regression Approach

ABSTRACT The natural transition from walking to running occurs in adults at ≅140 steps/min. It is unknown when this transition occurs in children and adolescents. The purpose of this study was to develop a model to predict age- and anthropometry-specific preferred transition cadences in individuals 6–20 years of age. Sixty-nine individuals performed sequentially faster 5-min treadmill walking bouts, starting at 0.22 m/s and increasing by 0.22 m/s until completion of the bout during which they freely chose to run. Steps accumulated during each bout were directly observed and converted to cadence (steps/min). A logistic regression model was developed to predict preferred transition cadences using the best subset of parameters. The resulting model, which included age, sex, height, and BMI z-score, produced preferred transition cadences that accurately classified gait behaviour (k-fold cross-validated prediction accuracy =97.02%). This transition cadence ranged from 136–161 steps/min across the developmental age range studied. The preferred transition cadence represents a simple and practical index to predict and classify gait behaviour from wearable sensors in children, adolescents, and young adults. Moreover, herein we provide an equation and an open access online R Shiny app that researchers, practitioners, or clinicians can use to predict individual-specific preferred transition cadences.

Effects of Auditory Cueing on Cadence and Gait Pattern

A large portion of the population participate in gait rehabilitation, especially those with conditions such as increased fall risk such as stroke, or Parkinson’s Disease. Some studies have shown that auditory cues help improve gait and reduce fall risk, but relationship with gait patterns is missing. In this study, eight participants walked at their preferred cadence and at increased and reduced cadence by 20%. We found that step length and step width were not significantly different in all walking conditions. Decreased cadence resulted in an increase of swing time, stance time, stride time, and stance to swing ratio, and a decrease in stride length. Increased cadence resulted in a decrease in stance time, stride time, swing time, and stance to swing ratio, and an increase in stride length. The results suggest there is a strong correlation between auditory cues and gait patterns that can improve rehabilitative processes in the future.

BeatPark: Personalized Music-Based Gait Rehabilitation in Parkinson's Disease

Background: Walking regularly in Parkinson’s disease has beneficial effects on movement and quality of life. Yet, patients usually show reduced physical activity compared to healthy older adults. Using auditory stimulation, such as music, can facilitate walking but patients vary significantly in their response to the stimulus. An individualized approach adapting musical tempo to patients’ gait cadence, and capitalizing on these individual differences, is likely to provide a rewarding experience, with beneficial effects on gait in Parkinson’s disease. We aim to evaluate the observance, safety, tolerance, usability and enjoyment of a new smartphone application coupled with wearable sensors (BeatPark) delivering individualized musical stimulation for gait auto-rehabilitation at home. Methods: Forty-five patients with Parkinson’s disease underwent a one month, outdoor, gait rehabilitation program, using the BeatPark application (30 min/day, 5 days/week). The music tempo was aligned in real time to patients’ gait cadence while fostering an increase of cadence up to +20% of the patient’s preferred cadence. Evaluation was based on BeatPark use measures, questionnaires and a six-minute walk test before and after the rehabilitation program. Findings: Patients used the application 78.8 % (±28.2) of the prescribed duration and mostly enjoyed it, across the whole program. 75 % of them rated the application as easy to use. While using BeatPark, patients increased their ‘walk for exercise’ duration and frequency, reduced their fear of falling, and improved their quality of life. After the program, they improved their gait parameters in the six-minute walk test. Interpretation BeatPark is an easy to use and enjoyable musical application for individualized gait rehabilitation in Parkinson’s disease increasing ‘walk for exercise’ duration, confidence in gait and quality of life. Trial Registration: NCT02647242 Funding: This research was supported by a European grant: BeatHealth: Health and Wellness on the Beat (EU FP7-ICT contract #610633). Declaration of Interests: None to declare. Ethics Approval Statement: The study was approved by the National Ethics Committee (CPP Sud Mediterannee III, Nimes, France, ID-RCB: 2015-A00531-48). All participants gave written informed consent before participating.

Effects of 12-week cadence retraining on impact peak, load rates and lower extremity biomechanics in running.

BackgroundExcessive impact peak forces and vertical load rates are associated with running injuries and have been targeted in gait retraining studies. This study aimed to determine the effects of 12-week cadence retraining on impact peak, vertical load rates and lower extremity biomechanics during running.MethodsTwenty-four healthy male recreational runners were randomised into either a 12-week cadence retraining group (n = 12), which included those who ran with a 7.5% increase in preferred cadence, or a control group (n = 12), which included those who ran without any changes in cadence. Kinematics and ground reaction forces were recorded simultaneously to quantify impact force variables and lower extremity kinematics and kinetics.ResultsSignificantly decreased impact peak (1.86 ± 0.30 BW vs. 1.67 ± 0.27 BW, P = 0.003), vertical average load rates (91.59 ± 18.91 BW/s vs. 77.31 ± 15.12 BW/s, P = 0.001) and vertical instantaneous load rates (108.8 ± 24.5 BW/s vs. 92.8 ± 18.5 BW/s, P = 0.001) were observed in the cadence retraining group, while no significant differences were observed in the control group. Foot angles (18.27° ± 5.59° vs. 13.74° ± 2.82°, P = 0.003) and vertical velocities of the centre of gravity (CoG) (0.706 ± 0.115 m/s vs. 0.652 ± 0.091 m/s, P = 0.002) significantly decreased in the cadence retraining group at initial contact, but not in the control group. In addition, vertical excursions of the CoG (0.077 ± 0.01 m vs. 0.069 ± 0.008 m, P = 0.002) and peak knee flexion angles (38.6° ± 5.0° vs. 36.5° ± 5.5°, P < 0.001) significantly decreased whilst lower extremity stiffness significantly increased (34.34 ± 7.08 kN/m vs. 38.61 ± 6.51 kN/m, P = 0.048) in the cadence retraining group. However, no significant differences were observed for those variables in the control group.ConclusionTwelve-week cadence retraining significantly increased the cadence of the cadence retraining group by 5.7%. This increased cadence effectively reduced impact peak and vertical average/instantaneous load rates. Given the close relationship between impact force variables and running injuries, increasing the cadence as a retraining method may potentially reduce the risk of impact-related running injuries.

Effect of Q-factor manipulation via pedal spacers on lower limb frontal plane kinematics during cycling

Anecdotal evidence suggests that frontal plane kinematics of the lower extremity are an important aspect of bicycle fit, however, frontal plane adjustments are often overlooked during common fitting procedures. The purpose of this study was to manipulate Q-factor width via pedal spacers to determine their influence on frontal plane kinematics of the hip, knee, and ankle during cycling. Twenty-four young healthy recreational cyclists (12 female) completed five minutes of pedaling at their preferred cadence and power output under three stance widths conditions: no spacer, 20 mm spacer, and 30 mm spacer. For each participant, the pedaling cadence and power output were kept identical for all experimental conditions. Lower extremity marker position data were captured at 250 Hz for the last two minutes of each condition. Sixty consecutive crank cycles were analyzed to identify maximum and minimum hip, knee, and ankle angles in the frontal plane. With an increase in Q-factor, hip and knee maximum abduction angles increased and maximum adduction angles decreased. With increase in Q-factor from no spacer to 20 mm spacer condition, hip abduction increased by 0.8o (∆10%; p&lt;0.001) whereas hip abduction decreased by 0.9o (∆23%; p&lt;0.001) and similarly, knee abduction increased by 1.2o (∆60%; p=0.002) whereas knee abduction decreased by 1.1o (∆18%; p=0.003). And with increase in Q-factor from no spacer to 30 mm spacer condition, hip abduction increased by 1.4o (∆18%; p&lt;0.001) and hip adduction decreased by 1.6o (∆40%; p&lt;0.001) and similarly, knee abduction increased by 1.8o (∆86%; p&lt;0.001) and knee adduction decreased by 2.1o (∆35%; p&lt;0.001). Maximum and minimum ankle angles were not affected by the stance width conditions (p&gt;0.05). Pedal spacers are an effective way of manipulating Q-factor and frontal plane kinematics of the hip and knee and could help cyclists experiencing medial or lateral knee pain.

A "Step-Ramp-Step" Protocol to Identify the Maximal Metabolic Steady State.

This study aimed to test the efficacy of a "step-ramp-step" (SRS) cycling protocol for estimating the PO at RCP and the validity of RCP as a maximal metabolic steady-state surrogate. Ten heathy volunteers (5 women; age: 30 ± 7 yr; V[Combining Dot Above]O2max: 54 ± 6 mL·kg·min) performed in the following series: a moderate step transition to 100 W (MOD), ramp (30 W·min), and after 30 min of recovery, step transition to ~50% POpeak (HVY). Ventilatory and gas exchange data from the ramp were used to identify the V[Combining Dot Above]O2 at lactate threshold (LT) and RCP. The PO at LT was determined by the linear regression of the V[Combining Dot Above]O2 versus PO relationship after adjusting ramp data by the difference between the ramp PO at the steady-state V[Combining Dot Above]O2 from MOD and 100 W. Linear regression between the V[Combining Dot Above]O2-PO values associated with LT and HVY provided, by extrapolation, the PO at RCP. Participants then performed 30-min constant-power tests at the SRS-estimated RCP and 5% above this PO. All participants completed 30 min of constant-power exercise at the SRS-estimated RCP achieving steady-state V[Combining Dot Above]O2 of 3176 ± 595 mL·min that was not different (P = 0.80) from the ramp-identified RCP (3095 ± 570 mL·min) and highly consistent within participants (bias = -26 mL·min, r = 0.97, coefficient of variation = 2.3% ± 2.8%). At 5% above the SRS-estimated RCP, four participants could not complete 30 min and all, but two exhibited non-steady-state responses in blood lactate and V[Combining Dot Above]O2. In healthy individuals cycling at their preferred cadence, the SRS protocol and the RCP are capable of accurately predicting the PO associated with maximal metabolic steady state.

The reliability and validity of the 3-minute critical power test

Background: Athletes utilise exercise testing to assist with training design and race strategy. Critical power (CP) is a useful addition to an exercise testing battery as it provides an estimate of the heavy-severe exercise domain boundary (Vanhatalo et al., 2007: Medicine & Science in Sports & Exercise, 39(3), 548-55). Although the benefits of calculating CP are known, the traditional CP test protocol is excessively time consuming. Studies have suggested that CP can be obtained from a single 3-minute bout of ‘all-out’ exercise using the Lode Excalibur Sport cycle ergometer in linear mode (Vanhatalo et al., 2008: Medicine & Science in Sports & Exercise, 40(9), 1693-9). A more recent study (Karsten et al., 2013: International Journal of Sports Medicine, 35(4), 304-9) suggests that the 3-minute test does not provide a valid measure of critical power when using the SRM cycle ergometer in isokinetic mode. Purpose: To investigate the reliability and validity of the 3-minute critical power test in both isokinetic and linear modes using the Lode Excalibur Sport. Methods: Six male cyclists (mean ± SD; age 33 ± 7.7 yr, body mass 83.42 ± 9.9 kg, maximum aerobic power (MAP) 343 ± 50 W, VI‡O2max 4.38 ± 0.77 L•min-1) gave written informed consent to participate in the study, which was approved by Southampton Solent University’s ethics committee. Each participant took part in 8 trials, each separated by a minimum of 48 hours. The first trial took part in two stages. The first was an incremental step test (100 W start with 25 W increments every 3 minutes) to calculate gas exchange threshold (GET). The second stage was a ramp test (100 W start with 20 W•min-1 increments) to calculate MAP and VI‡O2max. During trials 2–4, each participant completed three efforts to exhaustion (80, 100 and 105% MAP). The results from these trials were used to calculate critical power, which included both the 1/time (CP1) and work–time (CP2) critical power models. Traditionally, these models have both been used to calculate CP. The final four trials were used to estimate critical power from two separate 3-minute protocols. Two trials were carried out using the linear mode following the protocol described by Vanhatalo et al. (2008). The two remaining trials were carried out in the isokinetic mode at the participant’s preferred cadence following the protocol described by Karsten et al. (2013). Apart from trial one, all testing sessions were carried out in a randomized order. A repeated measures ANOVA was used to compare CP and End Power (EP) with significance set at p<0.05. Coefficient of variation was used to compare EP-isokinetic and EP-linear between each testing session. For reliability to be seen in sports science testing it has been suggested that a CV of less than 5% is required (Hopkins, 2000: A new view on statistics. Retrieved 31 March 2014, from http://www.sportsci.org/resource/stats). Results: There was no significant difference between EP-isokinetic and CP1 (+2.6 W, p=0.80) or between EP-isokinetic and CP2 (+5.1 W, p=0.46). There were significant differences between EP-linear and CP1 (+31.5 W, p=0.01) and between EP-linear and CP2 (+39.2 W, p=0.02). Coefficient of variation in EP-isokinetic and EP-linear was 3.35% and 1.15%, respectively. Discussion: To the authors’ knowledge this is the first time that the linear and isokinetic modes have been evaluated in a single cohort. The results suggest that the 3-minute isokinetic test provides a reliable measure of EP and a valid measure of CP. Although the 3-minute linear test seems to provide a reliable measure of EP, these results suggest that it does not provide a valid measure of CP. Therefore, the results from this pilot study do not fully support previous literature (Vanhatalo et al., 2008; Karsten et al., 2013). Conclusion: This study provides preliminary evidence to suggest that the 3-minute isokinetic testing protocol can be used to estimate the heavy-severe exercise domain boundary.

Footwear and Cadence Affect Gait Variability in Runners with Patellofemoral Pain.

To examine the effects of increased cadence and minimalist footwear on lower-limb variability in runners with patellofemoral pain (PFP). Fifteen (12 female, 3 male) runners with PFP ran on an instrumented treadmill with three-dimensional motion capture in three randomly ordered conditions: (i) standard shoe at preferred cadence, (ii) standard shoe +10% cadence, and (iii) minimalist shoe at preferred cadence. Vector coding was used to calculate coordination variability between strides for select lower-limb joint couplings. Approximate entropy was calculated to assess continuous variability for segment kinematic and kinetic data and compared between conditions using repeated-measures ANOVA. One-dimensional statistical parametric mapping repeated-measures ANOVA was performed on the coordination variability data. Cohen's d effect size was calculated for all comparisons. Larger approximate entropy values (i.e., greater variability) were observed for the standard shoe +10% cadence versus the standard shoe at preferred cadence for hip flexion/extension (P < 0.001; d = 1.12), hip adduction/abduction (P < 0.001; d = 0.99) and ankle dorsiflexion/plantarflexion (P < 0.001; d = 1.37) kinematics, and knee flexion/extension moments (P < 0.001; d = 0.93). Greater variability was also observed in the minimalist shoe versus the standard shoe at preferred cadence for hip internal/external rotation moments (P < 0.001; d = 0.76), knee adduction/abduction moments (P < 0.001; d = 0.51), and knee internal/external rotation moments (P < 0.001; d = 1.02). One-dimensional statistical parametric mapping repeated-measures ANOVA revealed no significant differences in coordination variability between running conditions. Greater hip and knee kinematic and kinetic variability observed with either increased cadence or minimalist footwear may be beneficial for those with PFP.

Mental Singing Reduces Gait Variability More Than Music Listening for Healthy Older Adults and People With Parkinson Disease.

Previously, we showed that internal cues (such as singing) produce similar motor benefits as external cues (such as listening to music) for people with Parkinson disease (PD). This study takes that research further by exploring how singing-either aloud or mentally-at different tempos can ameliorate gait, and it offers insight into how internal cueing techniques may enhance motor performance for older adults and people with PD. Sixty participants aged 50 years and older (30 female) were recruited; 30 had PD and 30 were healthy age-matched controls. Participants completed walking trials involving internal and external cueing techniques at 90%, 100%, and 110% of preferred cadence. The effects of different cue types and rates were assessed in a repeated-measures cross-sectional study by comparing gait characteristics (velocity, cadence, stride length) and variabilities (coefficients of variation of stride length, stride time, single support time). All participants modified their cadence and stride length during cued conditions, resulting in changes in gait velocity closely reflecting expected changes based upon cue rate. External cues resulted in increased gait variability, whereas internal cues decreased gait variability relative to uncued walking. Variability decreases were more substantial during mental singing at tempos at or above preferred cadence. Matching movement to one's own voice improves gait characteristics while reducing gait variability for older adults and people with PD. Optimizing the use of internal cues to facilitate movement is an important step toward more effectively meeting the needs of people with gait disorders related to aging or neurological disease.Video Abstract available for more insights from authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A286).

The Effect of Cadence on the Mechanics and Energetics of Constant Power Cycling.

The aim of this study was to investigate the effect of cadence on joint level work and vastus lateralis (VL) fascicle mechanics while cycling at a constant, submaximal, power output. We hypothesized that preferred cycling cadence would enhance the power capacity of the VL muscle when compared with a more economical cadence. Furthermore, we predicted that the most economical cadence would coincide with minimal total electromyographic activity from the leg muscles. Metabolic cost, lower-limb kinematics, joint level work, VL fascicle mechanics, and muscle activation of the VL, rectus femoris, biceps femoris, gastrocnemius medialis, and soleus muscles were measured during cycling at a constant power output of 2.5 W·kg and cadences of 40, 60, 80, and 100 rpm. A preferred condition was also performed where cadence feedback was hidden from the participant. Metabolic cost was lowest at 60 rpm, but the mean preferred cadence was 81 rpm. The distribution of joint work remained constant across cadences, with the majority of positive work being performed at the knee. The preferred cadence coincided with the highest VL power capacity, without a significant penalty to efficiency, based on fascicle shortening velocity. Cycling at a higher cadence is preferred to ensure that the muscle's ability to produce positive power remains high. Further investigations are required to examine what feedback mechanism could be responsible for the optimization of this motor pattern.