Assessment of Maximum Oxygen Uptake in Elite Youth Soccer Players: A Comparative Analysis of Smartwatch Technology, Yoyo Intermittent Recovery Test 2, and Respiratory Gas Analysis.

The maximum oxygen uptake (VO2max) is a critical factor for endurance performance in soccer. Novel wearable technology may allow frequent assessment of V̇O2max during non-fatiguing warm-up runs of soccer players with minimal interference to soccer practice. The aim of this study was to assess the validity of VO2max provided by a consumer grade smartwatch (Garmin Forerunner 245, Garmin, Olathe, USA, Software:13.00) and the YoYo Intermittent Recovery Run 2 (YYIR2) by comparing it with respiratory gas analysis. 24 trained male youth soccer players performed different tests to assess VO2max: i) a treadmill test employing respiratory gas analysis, ii) YYIR2 and iii) during a non-fatiguing warm-up run of 10 min wearing a smartwatch as recommended by the device-manufacturer on 3 different days within 2 weeks. As the device-manufacturer indicates that validity of smartwatch-derived VO2max may differ with an increase in runs, 16 players performed a second run with the smartwatch to test this claim. The main evidence revealed that the smartwatch showed an ICC of 0.37 [95% CI: -0.25; 0.71] a mean absolute percentage error (MAPE) of 5.58% after one run, as well as an ICC of 0.54 [95% CI: -0.3; 8.4] and a MAPE of 1.06% after the second run with the smartwatch. The YYIR2 showed an ICC of 0.17 [95% CI: -5.7; 0.6]; and MAPE of 4.2%. When using the smartwatch for VO2max assessment in a non-fatiguing run as a warm-up, as suggested by the device manufacturer before soccer practice, the MAPE diminishes after two runs. Therefore, for more accurate VO2max assessment with the smartwatch, we recommend to perform at least two runs to reduce the MAPE and enhance the validity of the findings.

Concurrent validity and test-retest reliability of VALD ForceDecks' strength, balance, and movement assessment tests.

OBJECTIVES: To evaluate the concurrent validity and test-retest reliability of common movement, strength, and balance tests using portable uniaxial dual force plates. DESIGN: Repeated measures cross-sectional study. METHODS: Sixteen healthy individuals participated in two testing sessions, where they performed 12 different movement, strength, and balance tests. Vertical ground reaction force and centre of pressure data were collected using the VALD ForceDecks simultaneously with ground-embedded laboratory force plates. Concurrent validity was assessed using root mean square error for raw time-series data and Bland-Altman plots for discrete metrics. Test-retest reliability was assessed using intraclass correlation coefficients and minimal detectable changes. RESULTS: ForceDecks recorded vertical ground reaction forces and center of pressure with high accuracy compared to laboratory force plates. The mean bias between systems was negligible (<2 N or 0.1 mm), with small limits of agreement (<5 N or 1 mm). Overall, 530/674 (79%) showed good or excellent validity (<10% difference) and 611/773 (79%) had good or excellent reliability (intraclass correlation coefficient >0.75). ForceDecks reliability was similar to laboratory force plates (<0.07 intraclass correlation coefficient median difference for all metrics). CONCLUSIONS: Portable uniaxial force plates record highly accurate vertical ground reaction forces and center of pressure during a range of movement, strength, and balance tests. The VALD ForcDecks are a valid and reliable alternative to laboratory force plates when strict standardized testing and data analysis procedures are followed. Users should be aware of the validity and reliability characteristics of the tests and metrics they choose.

Assessment of the loaded squat jump and countermovement jump exercises with a linear velocity transducer: which velocity variable provides the highest reliability?

This study aimed to compare the between-session reliability of three typically measured velocity variables (mean velocity [MV], mean propulsive velocity [MPV], and maximum velocity [Vmax]) to assess vertical jump performance. Totally, 23 men had their squat jump (SJ) and countermovement jump (CMJ) tested against five different loading conditions (17, 30, 45, 60 and 75 kg) during two consecutive weeks. The two sessions of each jump type were performed within the same week separated by 48-72 h. The main finding was a significant difference in reliability between the variables, which were ranked from the highest to the lowest reliable as follows (median coefficient of variation [CV] and range): Vmax (CV = 2.35% [1.85%-3.23%]) >MV (CV = 3.29% [2.18%-4.40%]) >MPV (CV = 3.69% [2.08%-5.17%]). A significant variable × exercise interaction was also observed showing that the differences in reliability between the variables were meaningful during the SJ (MV: CV = 3.93% [3.06%-4.40%], MPV: CV = 4.61% [4.07%-5.17%], and Vmax: CV = 2.14% [1.85%-2.71%]), while no significant differences were observed for the CMJ (MV: CV = 2.43% [2.18%-3.70%], MPV: CV = 2.71% [2.08%-3.63%], and Vmax: CV = 2.40% [1.97%-3.23%]). These results suggest that the Vmax should be the recommended variable for obtaining a reproducible measure of lower-body ballistic performance, especially during the SJ exercise.

The 6-m Timed Hop Is Not a Suitable Clinical Assessment Tool for Use Following Anterior Cruciate Ligament Reconstruction.

CONTEXT: Single-leg hop tests are used to assess functional performance following anterior cruciate ligament (ACL) reconstruction. Recording 6-m timed hop scores using a stopwatch increases the potential for misclassification of patient status due to the number of error sources present. OBJECTIVE: To examine the consistency of pass/fail (>90% limb symmetry index [LSI]) decisions in athletes tested at discharge following ACL reconstruction during the 6-m timed hop and the agreement between different human raters using a stopwatch and an electronic timing system. SETTING: Clinic, rehabilitation. PARTICIPANTS: A total of 20 professional soccer players (age 24.6 [4.2] y; height 175.3 [10.2] cm; mass 73.6 [14.5] kg; 36 [10.5] wk following ACL reconstruction) volunteered to take part in this study. MAIN OUTCOME MEASURES: Two individual raters recorded each trial of the 6-m timed hop test on each limb with a stopwatch and an electronic timing system acted as the criterion measure. LSI scores were also computed with a pass score >90% LSI. RESULTS: No significant differences were observed between limbs for any scoring method (P > .05). Mean differences indicated the electronic timing system was slower than both human raters (P < .05). Five participants failed the test (<90% LSI) but on each occasion this was only recorded by one method of rating. Kappa statistics showed no agreement in LSI scores across all 3 methods of scoring (κ = -.13) and no agreement when comparing the light gates to individual raters and rater 1 versus 2 (κ < 0). 95% limits of agreement in LSI scores recorded values of approximately ±20%. CONCLUSIONS: The 6-m timed hop test recorded using a stopwatch is not a valid measure to make clinical decisions following ACL reconstruction. Systematic bias between methods also suggests that a stopwatch and electronic timing system cannot be used interchangeably.

Inertial Sensors Embedded in Smartphones as a Tool for Fatigue Assessment Based on Acceleration in Survivors of Breast Cancer.

BACKGROUND: Cancer-related fatigue is a symptom commonly reported in survivors of breast cancer and is the most variable symptom. Besides questionnaires like PIPER to assess cancer-related fatigue, there is a need to objectively measure fatigue. OBJECTIVE: The aim of this study was to assess the physiological dimension of fatigue based on acceleration during a 30-second maximal sit-to-stand test. DESIGN: This was a cross-sectional study. METHODS: Linear acceleration from a smartphone placed on the sternum was recorded in 70 survivors of breast cancer. Fourth-degree polynomial adjustment from the acceleration signal to the vertical and anterior-posterior axis was calculated. The fatigue temporal cut-off point was detected as a change in the curve slope of the first maximum point of acceleration. RESULTS: Women were aged 51.8 (8.9) years with a body mass index of 25.4 (5.1) Kg/m2. They performed 23.6 (6.57) number of repetitions. The mean fatigue cut-off point from the total sample was 10.2 (3.1) seconds. LIMITATIONS: Further research should employ time-prolonged tests to study acceleration behavior beyond 30 seconds as well as include a physiological criterion that justifies the nonlinear saturation of the acceleration-based criterion. CONCLUSIONS: This study assessed fatigue through a low-cost and easy-to-use methodology during a functional and widely used test such as 30-second maximal sit-to-stand. This would allow clinicians to assess fatigue in a short-effort exercise to individualize exercise prescription dose, measure changes during intervention, and track fatigue objectively throughout survivorship.

Feasibility and reliability of a physical fitness tests battery for adults with intellectual disabilities: The SAMU DIS-FIT battery.

BACKGROUND: People with intellectual disability (ID) have lower performances in physical fitness (PF) tests than people without ID, a situation that exists during all the life stages. However, the assessment of the FP of persons with ID often uses instruments that were designed for non-disabled people. AIM: To check the reliability and feasibility of 8 PF tests in adults with mild to moderate ID. METHODS: A cross-sectional study was carried out with a test-retest design in a maximum interval of 2 weeks with 240 adults (160 men and 80 women) with mild to moderate ID in order to assess the feasibility and reliability of the following 8 tests: body mass index (BMI), waist circumference (WC), the timed up & go test (TUG), the deep trunk flexion test (DTF), the hand grip test (HG), the timed stand test (TST), the 30-s sit-up (SUP) test, and the 6-min walk test (6MWT). The complete battery was called the SAMU-Disability Fitness Battery (SAMU-DISFIT). The psychometric properties of the battery, feasibility, reliability, the standard error of the measurement (SEM) and the minimal detectable change (MDC) were calculated. RESULTS: The TUG, DTF, HG, TST, and 6MWT showed an intraclass correlation coefficient (ICC) from fair to high reliability. Only the SUP test in men had an ICC lower than 0.7 and high SEM values. CONCLUSION: The psychometric properties provide robust data on the use of the SAMU-DISFIT battery in people with ID and can be considered a useful tool for assessing PF in adults with mild to moderate ID in future research.

The Test-Retest Reliability of Force Plate-Derived Parameters of the Countermovement Push-Up as a Power Assessment Tool.

CONTEXT: Muscular power output of the upper limb is a key aspect of athletic and sporting performance. Maximal power describes the ability to immediately produce power with maximal velocity at the point of release, impact, or takeoff, with research highlighting that the greater an athlete's ability to produce maximal power, the greater the improvement in athletic performance. Despite the importance of upper-limb power for athletic performance, there is presently no gold-standard test for upper-limb force development performance. OBJECTIVE: The aim of this study was to investigate the test-retest reliability of force plate-derived measures of the countermovement push-up in active males. DESIGN: Test-retest design. SETTING: Controlled laboratory. PARTICIPANTS: Physically active college athletes (age 24 [3] y, height 1.79 [0.08] m, body mass 81.7 [9.9] kg). INTERVENTION: Subjects performed 3 repetitions of maximal effort countermovement push-up trials on Kistler force plates on 2 separate test occasions 7 days apart. MAIN OUTCOME MEASURES: Peak force, mean force, flight time, rate of force development, and impulse were analyzed from the force-time curve. RESULTS: No significant differences between the 2 trial occasions were observed for any of the derived performance measures. Intraclass correlation coefficient and within-subject coefficient of variation calculations indicated performance measures to have moderate to very high reliability (intraclass correlation coefficient = .88-.98), coefficient of variation = 5.5%-14.1%). Smallest detectable difference for peak force (7.5%), mean force (8.6%), and rate of force development (11.2%) were small to moderate. CONCLUSION: Force platform-derived kinetic parameters of countermovement push-up are reliable measurements of power in college-level athletes.

Assessment of energy expenditure during high intensity cycling and running using a heart rate and activity monitor in young active adults.

OBJECTIVE: Although high intensity physical activities may represent a great proportion of the total energy expenditure in active people, only sparse studies have investigated the accuracy of wearable monitors to assess activity related energy expenditure (AEE) during high intensity exercises. Therefore, the purpose of the present study was to investigate the accuracy of the Actiheart, a light portable monitor estimating AEE based on heart rate (HR) and activity counts (ACT), during two popular activities (running and cycling) performed at high intensities. The benefit of an individual calibration of the HR-AEE relationship established during a preliminary maximal test was also evaluated. METHODS: AEE was estimated in eighteen active adults (4 women and 14 men; 25 ± 4 yr) with indirect calorimetry using a respiratory gas analysis system (reference method) and the Actiheart during 5-min running and cycling at 60, 75 and 85% of maximal oxygen uptake (VO2max) previously determined during a maximal test performed on a treadmill or cycle ergometer. For the Actiheart, AEE was estimated either using the group or individual calibrated equations available in the dedicated software, and their respective HR, ACT or combined HR/ACT algorithms. RESULTS: When the HR algorithm was used for cycling and the HR or HR/ACT algorithms for running, AEE measured by the Actiheart increased proportionally to exercise intensity from 60 to 85% VO2max (P<0.001). Compared to indirect calorimetry, the Actiheart group calibrated equations slightly to moderately underestimated (3 to 20%) AEE for the three exercise intensities (P<0.001). Accuracy of AEE estimation was greatly improved by individual calibration of the HR-AEE relationship (underestimation below 5% and intraclass correlation coefficient [ICC]: 0.79-0.93) compared to group calibration (ICC: 0.64-0.79). CONCLUSION: The Actiheart enables to assess AEE during high intensity running and cycling when the appropriate algorithm is applied. Since an underestimation was present for group calibration, an individual and sport-specific calibration should be performed when a high accuracy is required.

Diagnostic test accuracy of an automated device as a screening tool for fall risk assessment in community-residing elderly: A STARD compliant study.

We aimed to determine the accuracy and failure of OAK device, an automated screening, for the assessment of fall risk in a prospective cohort of healthy adults aged over 65 years. The algorithm for fall risk assessment of the centers for disease control and prevention (CDC) was used as reference standard. Of the 183 individuals recruited, the CDC algorithm classified 80 as being at moderate/high risk and 103 at low risk of falling. OAK device failure incidence was 4.9% (confidence interval [CI] upper limit 7.7%), below the preset threshold for futility-early termination of the study (i.e., not above 15%). The OAK device showed a sensitivity of 84% and a specificity of 67% (receiver operating characteristic [ROC] area 82%; 95% confidence interval [CI] 76-88%), not reaching the preplanned target sensitivity (not lower than 85%). Diagnostic accuracy was not far from the sensitivity levels similar to those obtained with other fall risk assessment. However, some limitations can be considered.ClinicalTrials.gov identifier: NCT02655796.

The Automatic Assessment of Strength and Mobility in Older Adults: A Test-Retest Reliability Study.

Background: Simple field tests such as the Timed Up and Go test (TUG) and 30 s Chair Stand test are commonly used to evaluate physical function in the elderly, providing crude outcome measures. Using an automatic chronometer, it is possible to obtain additional kinematic parameters that may lead to obtaining extra information and drawing further conclusions. However, there is a lack of studies that evaluate the test-retest reliability of these parameters, which may help to judge and interpret changes caused by an intervention or differences between populations. Thus, the aim of this study was to evaluate the test-retest reliability of the Timed Up and Go test (TUG) and 30 s Chair Stand test in healthy older adults. Methods: A total of 99 healthy older adults participated in this cross-sectional study. The TUG and the 30 s Chair Stand test were performed five times and twice, respectively, using an automatic chronometer. The sit-to-stand-to-sit cycle from the 30 s Chair Stand test was divided into two phases. Results: Overall, reliability for the 30 s Chair Stand test was good for almost each variable (intraclass correlation coefficient (ICC) >0.70). Furthermore, the use of an automatic chronometer improved the reliability for the TUG (ICC >0.86 for a manual chronometer and ICC >0.88 for an automatic chronometer). Conclusions: The TUG and the 30 s Chair Stand test are reliable in older adults. The use of an automatic chronometer in the TUG is strongly recommended as it increased the reliability of the test. This device enables researchers to obtain relevant and reliable data from the 30 s Chair Stand test, such as the duration of the sit-to-stand-to-sit cycles and phases.

Reliability and Concurrent Validity of Seven Commercially Available Devices for the Assessment of Movement Velocity at Different Intensities During the Bench Press.

Pérez-Castilla, A, Piepoli, A, Delgado-García, G, Garrido-Blanca, G, and García-Ramos, A. Reliability and concurrent validity of seven commercially available devices for the assessment of movement velocity at different intensities during the bench press. J Strength Cond Res 33(5): 1258-1265, 2019-The aim of this study was to compare the reliability and validity of 7 commercially available devices to measure movement velocity during the bench press exercise. Fourteen men completed 2 testing sessions. One-repetition maximum (1RM) in the bench press exercise was determined in the first session. The second testing session consisted of performing 3 repetitions against 5 loads (45, 55, 65, 75, and 85% of 1RM). The mean velocity was simultaneously measured using an optical motion sensing system (Trio-OptiTrack; "gold-standard") and 7 commercially available devices: 1 linear velocity transducer (T-Force), 2 linear position transducers (Chronojump and Speed4Lift), 1 camera-based optoelectronic system (Velowin), 1 smartphone application (PowerLift), and 2 inertial measurement units (IMUs) (PUSH band and Beast sensor). The devices were ranked from the most to the least reliable as follows: (a) Speed4Lift (coefficient of variation [CV] = 2.61%); (b) Velowin (CV = 3.99%), PowerLift (3.97%), Trio-OptiTrack (CV = 4.04%), T-Force (CV = 4.35%), and Chronojump (CV = 4.53%); (c) PUSH band (CV = 9.34%); and (d) Beast sensor (CV = 35.0%). A practically perfect association between the Trio-OptiTrack system and the different devices was observed (Pearson's product-moment correlation coefficient (r) range = 0.947-0.995; p < 0.001) with the only exception of the Beast sensor (r = 0.765; p < 0.001). These results suggest that linear velocity/position transducers, camera-based optoelectronic systems, and the smartphone application could be used to obtain accurate velocity measurements for restricted linear movements, whereas the IMUs used in this study were less reliable and valid.

Metabolic Costs During Backward Running with Body Weight Support.

We investigated metabolic costs, rating of perceived exertion (RPE), stride frequency (SF), and preferred speed (PS) during forward and backward running at different levels of body weight support (BWS). Participants completed forward and backward running on a lower body positive pressure treadmill at their preferred speed for forward and backward running at 0%BWS, 20%BWS, and 50%BWS. Oxygen uptake (V̇O2), heart rate (HR), RPE, SF, and PS were measured. HR, RPE, and SF during forward and backward running decreased with increasing BWS (P<0.05).V̇O2 during both forward and backward running at 50%BWS was significantly lower than when running at 0%BWS (P<0.01). However, PS during forward and backward running increased with increasing BWS (P<0.01). Furthermore,V̇O2 was different between running directions only when running at 0%BWS (P<0.01). HR and RPE were not different between running directions (P>0.05). SF during backward running was higher than that of forward running (P<0.01). PS during backward running was lower than when running forward (P<0.001). Our observations suggest that individuals may select PS and SF during running with BWS in a way that resulted in similar metabolic costs, regardless of direction of locomotion.

[Physical activity assessment using accelerometry]. / Quantification de l'activité physique par l'accélérométrie.

Physical activity is an important determinant of health in children and adults. Assessment of physical activity is therefore an important factor in the promotion of health and in several childhood and adulthood pathological situations. Physical activity can be estimated by various methods: pedometry, heart rate monitoring, questionnaires, the doubly labelled water method, and accelerometry. The choice of the type of device depends on the objectives of the clinician or researcher. Accelerometry currently represents the best objective method for measuring physical activity and is widely used in clinical or epidemiological studies. The purpose of this paper is to help practitioners and researchers to make better decisions when using accelerometry as a device for measuring physical activity measurement in order to obtain the most accurate and comparable information.

Turning a cylindrical treadmill with feet: An MR-compatible device for assessment of the neural correlates of lower-limb movement.

BACKGROUND: Locomotion, which is one of the most basic motor functions, is critical for performing various daily-life activities. Despite its essential function, assessment of brain activity during lower-limb movement is still limited because of the constraints of existing brain imaging methods. NEW METHOD: Here, we describe an MR-compatible, cylindrical treadmill device that allows participants to perform stepping movements on an MRI scanner table. The device was constructed from wood and all of the parts were handmade by the authors. RESULTS: We confirmed the MR-compatibility of the device by evaluating the temporal signal-to-noise ratio of 64 voxels of a phantom during scanning. Brain activity was measured while twenty participants turned the treadmill with feet in sync with metronome sounds. The rotary speed of the cylinder was encoded by optical fibers. The post/pre-central gyrus and cerebellum showed significant activity during the movements, which was comparable to the activity patterns reported in previous studies. Head movement on the y- and z-axes was influenced more by lower-limb movement than was head movement on the x-axis. Among the 60 runs (3 runs × 20 participants), head movement during two of the runs (3.3%) was excessive due to the lower-limb movement. COMPARISON WITH EXISTING METHODS: Compared to MR-compatible devices proposed in the previous studies, the advantage of this device may be simple structure and replicability to realize stepping movement with a supine position. CONCLUSIONS: Collectively, our results suggest that the treadmill device is useful for evaluating lower-limb-related neural activity.

An instrumented object for hand exercise and assessment using a pneumatic pressure sensor.

Measurement of grip force is important for both exercise training and assessment of the hand during physical rehabilitation. The standard method uses a grip dynamometer which measures the force between the fingers and opposing thumb. The primary limitation of the grip dynamometer is the restriction of measurement to cylindrical grasps. Any deformation of the hand due to muscular or skeletal disease makes the grip dynamometer difficult or impossible to use. An alternative to the grip dynamometer is a sealed pneumatic object that can be gripped by the hand. Measurement of the internal pressure in the object can be related to the grip force. In this paper, we analyze such a pneumatic pressure sensing object for hand grip assessment and also describe an easy fabrication of the grip sensor. The instrumented object presented in this paper is designed to assess both the maximal voluntary grip forces and continuous grip force to monitor control of hand function during exercise under instruction from a therapist. Potential uses of such a pneumatic pressure sensing object for hand grip are in physical rehabilitation of patients following paralysing illnesses like stroke and spinal cord injury.

Assessment of Knee Kinetic Symmetry Using Force Plate Technology.

CONTEXT: Athletes who have undergone an anterior cruciate ligament reconstruction often demonstrate more pronounced interlimb knee kinetic symmetry in comparison with uninjured athletes, even after they have completed rehabilitation. Part of the reason for the persistent asymmetry may be that sports medicine professionals are typically not able to assess knee joint kinetics within the clinic setting. Developing measures to assess knee joint kinetic symmetry could help to augment current rehabilitation practices. OBJECTIVE: The purpose of this study was to explore the extent to which interlimb vertical ground reaction force (GRF) symmetry can predict knee kinetic symmetry during a drop landing task. DESIGN: Cross-sectional study. SETTING: Motion analysis laboratory. PARTICIPANTS: A total of 21 uninjured subjects (9 males and 12 females). PROTOCOL: Three-dimensional kinematic data were collected using a multicamera system while subjects performed double-leg drop landings. GRF data were collected synchronously using 2 adjacent force plates. MAIN OUTCOME MEASURES: Knee joint moments and power were calculated for both limbs during the landing trials. An interlimb symmetry index (dominant/nondominant limb) was calculated for both the peak knee joint moment and power variables, as well as for the peak vertical GRFs. Linear regression analyses were performed to determine if the degree of symmetry in the peak vertical GRFs predicted the degree of symmetry for the kinetic variables. RESULTS: The symmetry index for the vertical GRFs was a significant predictor of the symmetry indices for the knee joint moments (r = .81; P < .001) and power (r = .88; P < .001). CONCLUSION: Interlimb symmetry in the peak vertical GRFs can be used to predict knee joint kinetic symmetry during a double-leg drop landing task.

Reliability and validity of the Wii Balance Board for assessment of standing balance: A systematic review.

The use of force platform technologies to assess standing balance is common across a range of clinical areas. Numerous researchers have evaluated the low-cost Wii Balance Board (WBB) for its utility in assessing balance, with variable findings. This review aimed to systematically evaluate the reliability and concurrent validity of the WBB for assessment of static standing balance. Articles were retrieved from six databases (Medline, SCOPUS, EMBASE, CINAHL, Web of Science, Inspec) from 2007 to 2017. After independent screening by two reviewers, 25 articles were included. Two reviewers performed the data extraction and quality assessment. Test-retest reliability was investigated in 12 studies, with intraclass correlation coefficients or Pearson's correlation values showing a range from poor to excellent reliability (range: 0.27 to 0.99). Concurrent validity (i.e. comparison with another force platform) was examined in 21 studies, and was generally found to be excellent in studies examining the association between the same outcome measures collected on both devices. For studies reporting predominantly poor to moderate validity, potentially influential factors included the choice of 1) criterion reference (e.g. not a common force platform), 2) test duration (e.g. <30 s for double leg), 3) outcome measure (e.g. comparing a centre of pressure variable from the WBB with a summary score from the force platform), 4) data acquisition platform (studies using Apple iOS reported predominantly moderate validity), and 5) low sample size. In conclusion, evidence suggests that the WBB can be used as a reliable and valid tool for assessing standing balance. Protocol registration number: PROSPERO 2017: CRD42017058122.

Kinematics and metabolic cost of running on an irregular treadmill surface.

The purpose of this study was to investigate the kinematic and metabolic effects of running on an irregular surface. We also examined how altering the frontal plane foot angle (inversion/eversion) at contact using real-time visual feedback would affect these other variables. Sixteen participants completed three running bouts lasting 5-7 minutes each on an irregular surface (IS) treadmill, a traditional smooth surface (SS) treadmill, and on SS while receiving visual feedback of the frontal plane foot angle at contact (SSF) with a goal of matching IS foot angle on SS. Frontal plane foot angle increased 40% from IS to SS (IS: 8.4 ± 4.09°, SS: 11.8 ± 4.52°, P < 0.0001, ES 1.40). Knee flexion angle at contact decreased 33% from IS to SS (IS: 9.2 ± 4.88°, SS: 6.2 ± 5.03°, P < 0.0001, ES 1.30). Rate of oxygen consumption decreased by 10% from IS to SS (IS: 37.9 ± 5.68 ml·kg-1·min-1, SS: 34.1 ± 5.07 ml·kg-1·min-1, P < 0.0001, ES 3.05). PSD of leg accelerations decreased by 38% (IS: 0.17 ± 0.07 g2/Hz, SS: 0.106 ± 0.05 g2/Hz, P < 0.000, ES 1.69). Frontal plane foot angle decreased by 14% from SS to SSF (SS: 11.8 ± 4.52°, SSF: 10.1 ± 4.42°, P = 0.027. ES 0.62) but did not result in significant changes in any other variables. There were no significant differences in shock attenuation between any conditions (IS: -9.8 ± 2.26 dB, SS: -9.5 ± 3.12 dB, SSF: -9.9 ± 2.62 dB, P = 0.671). Running with greater eversion on the irregular surface may be an attempt by runners to reduce the perceived potential of an inversion ankle sprain. As a partial compensation for the decreased foot angle, runners increased knee flexion. This maintained shock attenuation but increased the rate of oxygen consumption. Altering the foot angle at contact using feedback on the SS caused the knee angle at contact to increase, but did not change shock attenuation or metabolic cost.

Evaluación de la actividad física en pacientes con enfermedad pulmonar obstructiva crónica / Tools for physical activity assessment in chronic obstructive pulmonary disease

The prevalence and mortality of chronic obstructive pulmonary disease (COPD) is increasing in Chile, constituting a public health problem. Pulmonary and systemic consequences of COPD affect physical activity, as the disease progresses. There are multiple means for physical activity assessment, from low cost and easily applicable questionnaires to sophisticated laboratory tests. Physical inactivity is a modifiable risk factor for morbidity and mortality in patients with COPD. Physical activity interventions not only contribute to decrease the likelihood of mortality, but also protect from comorbidities, especially cardiovascular ones. It also plays a major role avoiding functional limitations of these subjects. Dyspnea and fatigue render exercise as an unpleasant activity for most patients with COPD. If psychological alterations such as anxiety and depression are summed, these patients drift towards an inactive lifestyle. This article analyzes several tools available to assess physical activity is patients with COPD, useful in clinical practice.

Developing a Low-Cost Force Treadmill via Dynamic Modeling.

By incorporating force transducers into treadmills, force platform-instrumented treadmills (commonly called force treadmills) can collect large amounts of gait data and enable the ground reaction force (GRF) to be calculated. However, the high cost of force treadmills has limited their adoption. This paper proposes a low-cost force treadmill system with force sensors installed underneath a standard exercise treadmill. It identifies and compensates for the force transmission dynamics from the actual GRF applied on the treadmill track surface to the force transmitted to the force sensors underneath the treadmill body. This study also proposes a testing procedure to assess the GRF measurement accuracy of force treadmills. Using this procedure in estimating the GRF of "walk-on-the-spot motion," it was found that the total harmonic distortion of the tested force treadmill system was about 1.69%, demonstrating the effectiveness of the approach.