Muscle strength trajectories and their association with postoperative health-related quality of life in patients undergoing coronary artery bypass grafting surgery: a prospective cohort study.

BACKGROUND: Patients with sarcopenia have a higher risk of poor recovery after coronary artery bypass grafting (CABG). Little is known about the impact of changes in muscle strength (the primary indicator for sarcopenia) on health-related quality of life (HR-QoL). This study aimed to (1) identify subgroups with different muscle strength trajectories, (2) identify differences in preoperative risk factors among trajectory group membership, and (3) explore their prognostic value on postoperative HR-QoL in patients undergoing CABG. METHODS: In this prospective observational study 131 patients undergoing elective CABG completed grip strength tests and HR-QoL questionnaires. Latent Class Growth Mixture Modelling (LCGMM) was used to identify clinically relevant trajectories (> 5% of study population) for weight-normalised grip strength, measured at admission, 3 days, and 6 months after surgery. Differences between trajectory group membership at baseline were evaluated. The impact of trajectory group membership on postoperative HR-QoL was evaluated with multiple linear regression models. RESULTS: Due to low numbers (n = 15), female patients were excluded from LCGMM and subsequent statistical analyses. In males (n = 116), we identified two main weight-normalised grip strength trajectories: a "stable average" trajectory with a slight decline immediately post-surgery and recovery to preoperative levels (n = 85) and a "high" trajectory with a considerable immediate decline after surgery but followed towards a higher level of recovery compared to preoperative level (n = 27). The "stable average" patients were older (68 vs. 57 years; P = 0.003), had more diabetes (27% vs. 4%; P = 0.01) and had a higher BMI (27.8 vs. 24.8; P = 0.005) compared to the "high" group. After correction for age, diabetes, and baseline HR-QoL, group trajectory membership was not associated with postoperative HR-QoL, yet an increase in individual change scores of weight-normalised grip strength was associated with a better postoperative HR-QoL. We also identified one small trajectory group (n = 4, ≤ 5%). CONCLUSIONS: This study showed two relevant weight-normalised grip strength trajectories in male patients undergoing CABG, varying in important preoperative risk factors. While change scores of grip strength per weight did predict postoperative HR-QoL, the trajectory subgroups could not predict postoperative HR-QoL. Future research should focus on female patients, reacting potentially different on CABG and/or rehabilitation treatment. Trial registration NCT03774342, 12-12-2018.

Force-velocity profiling of elite wheelchair rugby players by manipulating rolling resistance over multiple wheelchair sprints.

This study investigated the effect of increased rolling resistance on wheelchair sprint performance and the concomitant force-velocity characteristics. Thirteen wheelchair rugby (WCR) athletes completed five 15 s wheelchair sprints in their own rugby wheelchair on an instrumented dual-roller wheelchair ergometer. The first sprint was performed against a close to overground resistance and in each of the following sprints, the resistance increased with 80% of that resistance. A repeated-measures ANOVA examined differences between sprints. Subsequently, linear regression analyses examined the individual force-velocity relations and then, individual parabolic power output curves were modeled. Increased rolling resistance led to significantly lower velocities (-36%), higher propulsion forces (+150%) and higher power outputs (+83%). These differences were accompanied by a lower push frequency, higher push time, yet a constant recovery time and contact angle. The modeled linear regressions (R2 = 0.71 ± 0.10) between force and velocity differed a lot in slope and intercept among individual athletes. The peak of the power output parabola (i.e., the optimal velocity) occurred on average at 3.1 ± 0.6 ms-1 . These individual force-velocity profiles can be used for training recommendations or technological changes to better exploit power generation capabilities of the WCR athletes' musculoskeletal system.

Development of a Portable Low-Cost System for the Metrological Verification of Wheelchair Roller Ergometers.

Wheelchair ergometers are widely used in research, clinical practice, and sports environments. The majority of wheelchair ergometers are roller systems that allow for wheelchair propulsion in the personal wheelchair on one or two (instrumented) rollers. Oftentimes these systems are only statically calibrated. However, wheelchair propulsion is dynamic by nature, requiring a dynamic validation process. The aim of the current project was to present a low-cost portable system for the dynamic metrological verification of wheelchair roller ergometers, based on an instrumented reference wheel. The tangential force on the roller is determined, along with its uncertainty, from the reference wheel properties, and compared with the force measured by the ergometer. Uncertainty of this reference wheel system was found to be lower than the one of the ergometer used, indicating that this novel approach can be used for the metrological verification of ergometers.

Implementing Exercise = Medicine in routine clinical care; needs for an online tool and key decisions for implementation of Exercise = Medicine within two Dutch academic hospitals.

BACKGROUND: There is much evidence to implement physical activity interventions for medical reasons in healthcare settings. However, the prescription of physical activity as a treatment, referring to as 'Exercise is Medicine' (E = M) is currently mostly absent in routine hospital care in The Netherlands. To support E = M prescription by clinicians in hospitals, this study aimed: (1) to develop an E = M-tool for physical activity advice and referrals to facilitate the E = M prescription in hospital settings; and (2) to provide an E = M decision guide on key decisions for implementation to prepare for E = M prescription in hospital care. METHODS: A mixed method design was used employing a questionnaire and face-to-face interviews with clinicians, lifestyle coaches and hospital managers, a patient panel and stakeholders to assess the needs regarding an E = M-tool and key decisions for implementation of E = M. Based on the needs assessment, a digital E = M-tool was developed. The key decisions informed the development of an E = M decision guide. RESULTS: An online supportive tool for E = M was developed for two academic hospitals. Based on the needs assessment, linked to the different patients' electronic medical records and tailored to the two local settings (University Medical Center Groningen, Amsterdam University Medical Centers). The E = M-tool existed of a tool algorithm, including patient characteristics assessed with a digital questionnaire (age, gender, PA, BMI, medical diagnosis, motivation to change physical activity and preference to discuss physical activity with their doctor) set against norm values. The digital E = M-tool provided an individual E = M-prescription for patients and referral options to local PA interventions in- and outside the hospital. An E = M decision guide was developed to support the implementation of E = M prescription in hospital care. CONCLUSIONS: This study provided insight into E = M-tool development and the E = M decision-making to support E = M prescription and facilitate tailoring towards local E = M treatment options, using strong stakeholder participation. Outcomes may serve as an example for other decision support guides and interventions aimed at E = M implementation.

Effects of 7-week Resistance Training on Handcycle Performance in Able-bodied Males.

The effect of an upper body resistance training program on maximal and submaximal handcycling performance in able-bodied males was explored. Eighteen able-bodied men were randomly assigned to a training group (TG: n=10) and a control group (CG: n=8). TG received 7 weeks of upper body resistance training (60% of 1 repetition maximum (1RM), 3×10 repetitions, 6 exercise stations, 2 times per week). CG received no training. Peak values for oxygen uptake (V˙O2peak), power output (POpeak), heart rate (HRpeak), minute ventilation (V˙OEpeak) and respiratory exchange ratio (RERpeak), submaximal values (HR, V˙O2, RER, PO, and gross mechanical efficiency (GE)), and time to exhaustion (TTE) were determined in an incremental test pre- and post-training. Maximal isokinetic arm strength and 1RM tests were conducted. Ratings of perceived exertion (RPE) were assessed. A two-way repeated measures ANOVA and post-hoc comparisons were performed to examine the effect of time, group and its interaction (p<0.05). TG improved on POpeak (8.55%), TTE (10.73%), and 1RM (12.28-38.98%). RPE at the same stage during pre- and post-test was lower during the post-test (8.17%). Despite no improvements in V˙O2peak, training improved POpeak, muscular strength, and TTE. Upper body resistance training has the potential to improve handcycling performance.

A novel push-pull central-lever mechanism reduces peak forces and energy-cost compared to hand-rim wheelchair propulsion during a controlled lab-based experiment.

BACKGROUND: Hand-rim wheelchair propulsion is straining and mechanically inefficient, often leading to upper limb complaints. Previous push-pull lever propulsion mechanisms have shown to perform better or equal in efficiency and physiological strain. Propulsion biomechanics have not been evaluated thus far. A novel push-pull central-lever propulsion mechanism is compared to conventional hand-rim wheelchair propulsion, using both physiological and biomechanical outcomes under low-intensity steady-state conditions on a motor driven treadmill. METHODS: In this 5 day (distributed over a maximum of 21 days) between-group experiment, 30 able-bodied novices performed 60 min (5 × 3 × 4 min) of practice in either the push-pull central lever wheelchair (n = 15) or the hand-rim wheelchair (n = 15). At the first and final sessions cardiopulmonary strain, propulsion kinematics and force production were determined in both instrumented propulsion mechanisms. Repeated measures ANOVA evaluated between (propulsion mechanism type), within (over practice) and interaction effects. RESULTS: Over practice, both groups significantly improved on all outcome measures. After practice the peak forces during the push and pull phase of lever propulsion were considerably lower compared to those in the handrim push phase (42 ± 10 & 46 ± 10 vs 63 ± 21N). Concomitantly, energy expenditure was found to be lower as well (263 ± 45 vs 298 ± 59W), on the other hand gross mechanical efficiency (6.4 ± 1.5 vs 5.9 ± 1.3%), heart-rate (97 ± 10 vs 98 ± 10 bpm) and perceived exertion (9 ± 2 vs 10 ± 1) were not significantly different between modes. CONCLUSION: The current study shows the potential benefits of the newly designed push-pull central-lever propulsion mechanism over regular hand rim wheelchair propulsion. The much lower forces and energy expenditure might help to reduce the strain on the upper extremities and thus prevent the development of overuse injury. This proof of concept in a controlled laboratory experiment warrants continued experimental research in wheelchair-users during daily life.

Effects of offloading devices on static and dynamic balance in patients with diabetic peripheral neuropathy: A systematic review.

Patients with diabetic peripheral neuropathy (DPN) usually have reduced somatosensory information and altered perception in feet and ankles. Somatosensory information acts as feedback for movement control and loss of somatosensation leads to altered plantar pressure patterns during gait and stance. Offloading devices are used to reduce peak plantar pressure and prevent diabetic foot ulcers. However, offloading devices can unfortunately have negative effects on static and dynamic balance. It is important to investigate these unwanted effects, since patient with DPN already are at high risk of falling and offloading devices could potentially increase this risk. The aim of this systematic review is to investigate the effects of plantar offloading devices used for ulcer prevention on their role in static and dynamic balance control in patients with DPN. PubMed and Embase were systematically searched using relevant search terms. After title selection, abstract selection, and full-text selection only five articles could be included for further analysis. Two articles included static balance measurements, two articles included dynamic balance measurements, and one article included both. Results suggested that static balance control is reduced when rocker bottom shoes and different insole configurations are used, however, toe-only rockers showed less evidence for reduced static balance control. There was no evidence for reduced dynamic balance control in combination with offloading devices. However, these results should be interpreted with care, since the number of studies was very small and the quality of the studies was moderate. Future research should evaluate balance in combination with different offloading devices, so that clinicians subscribing them are more aware of their potential unwanted consequences.

Traditional Cardiovascular Risk Factors Strongly Underestimate the 5-Year Occurrence of Cardiovascular Morbidity and Mortality in Spinal Cord Injured Individuals.

OBJECTIVES: To explore whether traditional models of cardiovascular disease (CVD) risk prediction correctly predict CVD events across a median 5.7-year follow-up period in individuals with spinal cord injury (SCI) and whether adding SCI-related characteristics (ie, lesion level) to the prediction model can improve the prognostic value. DESIGN: Retrospective analysis of patient records. SETTING: Observation at the start of active rehabilitation of participants in a multicenter cohort study, "Restoration of (Wheelchair) Mobility in SCI Rehabilitation," in the Netherlands. PARTICIPANTS: Patients with SCI (N=200) The patients were 74% men, aged 40±14 years, and with an American Spinal Injury Association (ASIA) impairment score of A through D. Forty percent had tetraplegia, and 69% were motor complete. INTERVENTIONS: Risk profiling/not applicable. MAIN OUTCOME MEASURES: Survival status and cardiovascular morbidity and mortality qwere obtained from medical records. Five-year Framingham Risk Scores (FRS) and the FRS ability to predict events assessed using receiver operating characteristic (ROC) curves with corresponding areas under the curve (AUC) and 95% confidence intervals (CI). Kaplan-Meier curves and the log-rank test were used to assess the difference in clinical outcome between participants with an FRS score lower or higher than the median FRS score for the cohort. SCI-related factors associated with CVD events, ASIA impairment, motor completeness, level of injury, and sports participation before injury were explored using univariate and multivariate Cox proportional hazard regression. RESULTS: The median 5-year FRS was 1.36%. Across a median follow-up period of 5.7 years, 39 developed a CVD event, including 10 fatalities. Although the FRS markedly underestimated the true occurrence of CVD events, the Kaplan-Meier curves and the log-rank test showed that the risk ratio for individuals with an FRS score less than the median FRS (eg, low risk) versus a score greater than the median FRS (high risk) was 3.2 (95% CI, 1.6-6.5; P=.001). Moreover, ROC with corresponding AUCs suggests acceptable accuracy of the FRS to identify individuals with increased risk for future CVD events (ROC AUC of 0.71; 95% CI, 0.62-0.82). Adding ASIA impairment (0.74; 95% CI, 0.66-0.82), motor impairment (0.74; 95% CI, 0.66-0.83), level of injury (0.72; 95% CI, 0.63-0.81), or active engagement in sport before injury (0.72; 95% CI, 0.63-0.88) to the FRS did not improve the level of discrimination. CONCLUSIONS: Our 5.7-year retrospective study reveals that cardiovascular risk factors and risk models markedly underestimate the true risk for CVD events in individuals with SCI. Nonetheless, these markers successfully distinguish between SCI individuals at high versus low risk for future CVD events. Our data may have future clinical implications, both related to (cutoff values of) CVD risk factors, but also for (earlier) prescription of (non)pharmacologic strategies against CVD in SCI individuals.

Shoulder Pain Is Associated With Rate of Rise and Jerk of the Applied Forces During Wheelchair Propulsion in Individuals With Paraplegic Spinal Cord Injury.

OBJECTIVE: To investigate the association between propulsion biomechanics, including variables that describe smoothness of the applied forces, and shoulder pain in individuals with spinal cord injury (SCI). DESIGN: Cross-sectional, observational study. SETTING: Non-university research institution. PARTICIPANTS: Community dwelling, wheelchair dependent participants (N=30) with chronic paraplegia between T2 and L1, with and without shoulder pain (age, 48.6±9.3y; 83% men). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Rate of rise and jerk of applied forces during wheelchair propulsion. Participants were stratified in groups with low, moderate, and high pain based on their Wheelchair User Shoulder Pain Index score on the day of measurement. RESULTS: A mixed-effect multilevel analysis showed that wheelchair users in the high pain group propelled with a significantly greater rate of rise and jerk, measures that describe smoothness of the applied forces, compared with individuals with less or no pain, when controlling for all covariables. CONCLUSIONS: Individuals with severe shoulder pain propelled with less smooth strokes compared to individuals with less or no pain. This supports a possible association between shoulder pain and rate of rise and jerk of the applied forces during wheelchair propulsion.

A portable isometric knee extensor strength testing device: test-retest reliability and minimal detectable change scores of the Q-Force ӀӀ in healthy adults.

BACKGROUND: Although knee extensors are essential in daily activities (e.g. walking, climbing stairs), knee extensor strength is often not measured in clinical settings. Existing devices to test muscle strength are not always suitable to accurately measure the high forces of this muscle group. Therefore, a device to test muscle strength that is convenient, feasible, reliable, and valid in clinical settings is required. This study evaluated the reliability, responsiveness, and level of discomfort of the newly developed Q-Force ӀӀ (i.e. a portable device to measure isometric knee extensor strength) in healthy middle-aged and elderly adults. METHODS: Participants (n = 22) conducted two standardized test sessions on the Q-Force ӀӀ (five to ten days apart). Each session consisted of one familiarisation trial followed by three trials of peak isometric knee extension per each leg. Per trial, peak and mean knee extension force (N) and torque (Nm) were measured at 90° flexion. The level of discomfort was determined using a visual analog scale (VAS: 0-100). Intra Class Correlation (ICC, model: two-way mixed with absolute agreement), Standard Error of Measurement (SEM), and minimal detectable change (MDC) were determined. A repeated measures ANOVA was used to determine between-test variation. RESULTS: Excellent test-retest (ICC > 0.95) and inter-trial (ICC > 0.91) reliability for both legs were shown. No significant differences were found in peak and mean knee forces and torques between test and retest of both legs, indicating good test-retest reliability (P-value range: 0.360-0.538; F(1,21) range: 0.4-0.9). The SEM of the peak and mean forces and torques ranged from 28.0 to 30.4 N (6.0-6.8%) and from 9.2 to 10.4 Nm (6.4-7.7%), respectively. The MDC for these outcomes ranged respectively from 77.6 to 84.1 N (16.5-18.8%) and from 25.5 to 28.9 Nm (17.6-21.4%). The level of discomfort was low (median range: 7-10, IQR: 4-18). CONCLUSION: The portable Q-Force ӀӀ is a comfortable, responsive, and relatively cheap device with excellent test-retest reliability. This device would be potentially suitable to measure isometric knee extensor strength in clinical settings.

Effect of a 7-week low intensity synchronous handcycling training programme on physical capacity in abled-bodied women.

This study evaluated the effect of a low-intensity norm duration synchronous handcycle wheelchair training in untrained able-bodied women. The training group (n = 9) received 7-weeks of low-intensity upper body training in an instrumented handcycle on a motor-driven treadmill (MDT), 3 × 30 min/week at 30% heart rate reserve. The control group (n = 10) received no training. Incremental handcycle tests on the MDT were used to determine peak values for oxygen uptake (VO2peak), power output (POpeak), heart rate (HRpeak), minute ventilation (VEpeak), and respiratory exchange ratio (RERpeak), submaximal values for heart rate (HR), oxygen uptake (VO2) and gross efficiency (GE) before and after training. Local perceived discomfort and rate of perceived exertion (RPE) were also assessed. Training significantly improved POpeak (+20%), HRpeak (+3%), RERpeak (+5%), submaximal GE (+21%), VO2 (-20%), VE (-33%), HR (-12%) and RPE was low (7.1 ± 0.5) (p < 0.05). No effects were found in VO2peak and VEpeak (p > 0.05). Though VO2peak did not improve, low-intensity norm duration handcycling training improved handcycling POpeak, while RPE was low. Also, GE increased, suggesting a motor control improvement. Handcycle training seems to be an appropriate exercise mode to improve physical capacity, and prevent early fatigue and overuse in untrained individuals.

A Role for Trunk Function in Elite Recumbent Handcycling Performance?

Handcycling classification considers trunk function, but there is limited scientific evidence of trunk involvement in recumbent performance. This study investigated the association between trunk function and recumbent handcycling performance of athletes without upper-limb impairments (H3-H4 sport classes). The study was divided into two parts. First, 528 time-trial results from 81 handcyclists with spinal cord injury (SCI) were obtained between 2014 and 2020. Average time-trial velocity was used as performance measure and SCI level as trunk function determinant. Multilevel regression analysis was performed to analyse differences in performance among SCI groups while correcting for lesion completeness, sex, and age. Second, in 26 handcyclists, standardised trunk flexion strength was measured with a handheld dynamometer. Peak and mean power-output from a sprint test and time-trial average velocity were used as performance measures. Spearman correlations were conducted to investigate the association between trunk strength and performance. Results showed that the different SCI groups did not exhibit significant differences in performance. Furthermore, trunk flexion strength and performance exhibited non-significant weak to moderate correlations (for time-trial speed: rs = 0.36; p = 0.07). Results of both analyses suggest that trunk flexion strength does not seem to significantly impact recumbent handcycling performance in athletes without upper-limb impairments.

Test-retest reliability and concurrent validity of the Adapted Short QUestionnaire to ASsess Health-enhancing physical activity (Adapted-SQUASH) in adults with disabilities.

The current study determined the test-retest reliability and concurrent validity of the Adapted Short QUestionnaire to ASsess Health-enhancing physical activity (Adapted-SQUASH) in adults with disabilities. Before filling in the Adapted-SQUASH twice with a recall period of 2 weeks, participants wore the Actiheart activity monitor up to 1 week. For the test-retest reliability (N = 68), Intraclass correlation coefficients (ICCs) were 0.67 (p < 0.001) for the total activity score (min x intensity/week) and 0.76 (p < 0.001) for the total minutes of activity (min/week). For the concurrent validity (N = 58), the Spearman correlation coefficient was 0.40 (p = 0.002) between the total activity score of the first administration of the Adapted-SQUASH and activity energy expenditure from the Actiheart (kcals kg-1 min-1). The ICC was 0.22 (p = 0.027) between the total minutes of activity assessed with the first administration of the Adapted-SQUASH and Actiheart. The Adapted-SQUASH is an acceptable measure to assess self-reported physical activity in large populations of adults with disabilities but is not applicable at the individual level due to wide limits of agreement. Self-reported physical activity assessed with the Adapted-SQUASH does not accurately represent physical activity assessed with the Actiheart in adults with disabilities, as indicated with a systematic bias between both instruments in the Bland-Altman analysis.

Changes in Quality of Life During Training for the HandbikeBattle and Associations With Cardiorespiratory Fitness.

OBJECTIVE: To investigate (1) changes in life satisfaction and mental health during 5 months of training for the HandbikeBattle and 4 months of follow-up; (2) associations between changes in handcycling cardiorespiratory fitness and changes in life satisfaction and mental health during the training period. DESIGN: This is a multicenter prospective cohort study with the following measurements: the start of the training (T1), after the 5-month training period, before the event (T2), and after 4 months of follow-up (T3). At T1, T2, and T3, questionnaires were filled out. At T1 and T2, a graded exercise test was performed to measure cardiorespiratory fitness (peak oxygen consumption [Vo2peak] and peak power output [POpeak]). SETTING: Ten Dutch rehabilitation centers training for the HandbikeBattle event. PARTICIPANTS: Patients with a rehabilitation history (N=136) and health conditions such as spinal cord injury, amputation, or multiple trauma history. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Life satisfaction as the sum score of 2 questions (range, 2-13) and the Mental Health subscale of the 36-item Short Form Health Survey (range, 0-100). RESULTS: Multilevel regression analyses showed that life satisfaction increased during the training period and did not significantly change during follow-up (mean ± SD, T1: 8.2±2.2; T2: 8.6±2.3; T3: 8.5±2.4). Mental health showed no change over time (T1: 77.7±14.5; T2: 77.8±14.5; T3: 75.7±16.5). An improvement in cardiorespiratory fitness was associated with an increase in life satisfaction (POpeak, ß=0.014, P=.046; Vo2peak, ß=1.068, P=.04). There were no associations between improvement in cardiorespiratory fitness and an increase in mental health (POpeak, P=.66; Vo2peak, P=.33). CONCLUSIONS: This study shows a positive course of life satisfaction during training for the HandbikeBattle. An improvement in cardiorespiratory fitness was longitudinally associated with an increase in life satisfaction. Mental health showed no changes over time.

Biomechanical and physiological differences between synchronous and asynchronous low intensity handcycling during practice-based learning in able-bodied men.

BACKGROUND: Originally, the cranks of a handcycle were mounted with a 180° phase shift (asynchronous). However, as handcycling became more popular, the crank mode switched to a parallel mounting (synchronous) over the years. Differences between both modes have been investigated, however, not into great detail for propulsion technique or practice effects. Our aim is to compare both crank modes from a biomechanical and physiological perspective, hence considering force and power production as a cause of physiological outcome measures. This is done within a practice protocol, as it is expected that motor learning takes place in the early stages of handcycling in novices. METHODS: Twelve able-bodied male novices volunteered to take part. The experiment consisted of a pre-test, three practice sessions and a post-test, which was subsequently repeated for both crank modes in a counterbalanced manner. In each session the participants handcycled for 3 × 4 minutes on a leveled motorized treadmill at 1.94 m/s. Inbetween sessions were 2 days of rest. 3D forces, handlebar and crank angle were measured on the left hand side. Kinematic markers were placed on the handcycle to monitor the movement on the treadmill. Lastly, breath-by-breath spirometry combined with heart-rate were continuously measured. The effects of crank mode and practice-based learning were analyzed using a two way repeated measures ANOVA, with synchronous vs asynchronous and pre-test vs post-test as within-subject factors. RESULTS: In the pre-test, asynchronous handcycling was less efficient than synchronous handcycling in terms of physiological strain, force production and timing. At the post-test, the metabolic costs were comparable for both modes. The force production was, also after practice, more efficient in the synchronous mode. External power production, crank rotation velocity and the distance travelled back and forwards on the treadmill suggest that asynchronous handcycling is more constant throughout the cycle. CONCLUSIONS: As the metabolic costs were reduced in the asynchronous mode, we would advise to include a practice period, when comparing both modes in scientific experiments. For handcycle users, we would currently advise a synchronous set-up for daily use, as the force production is more effective in the synchronous mode, even after practice.

Physiological and biomechanical comparison of overground, treadmill, and ergometer handrim wheelchair propulsion in able-bodied subjects under standardized conditions.

BACKGROUND: Handrim wheelchair propulsion is often assessed in the laboratory on treadmills (TM) or ergometers (WE), under the assumption that they relate to regular overground (OG) propulsion. However, little is known about the agreement of data obtained from TM, WE, and OG propulsion under standardized conditions. The current study aimed to standardize velocity and power output among these three modalities to consequently compare obtained physiological and biomechanical outcome parameters. METHODS: Seventeen able-bodied participants performed two submaximal practice sessions before taking part in a measurement session consisting of 3 × 4 min of submaximal wheelchair propulsion in each of the different modalities. Power output and speed for TM and WE propulsion were matched with OG propulsion, making them (mechanically) as equal as possible. Physiological data and propulsion kinetics were recorded with a spirometer and a 3D measurement wheel, respectively. RESULTS: Agreement among conditions was moderate to good for most outcome variables. However, heart rate was significantly higher in OG propulsion than in the TM condition. Push time and contact angle were smaller and fraction of effective force was higher on the WE when compared to OG/TM propulsion. Participants used a larger cycle time and more negative work per cycle in the OG condition. A continuous analysis using statistical parametric mapping showed a lower torque profile in the start of the push phase for TM propulsion versus OG/WE propulsion. Total force was higher during the start of the push phase for the OG conditions when compared to TM/WE propulsion. CONCLUSIONS: Physiological and biomechanical outcomes in general are similar, but possible differences between modalities exist, even after controlling for power output using conventional techniques. Further efforts towards increasing the ecological validity of lab-based equipment is advised and the possible impact of these differences -if at all- in (clinical) practice should be evaluated.

Do Handcycling Time-Trial Velocities Achieved by Para-Cycling Athletes Vary Across Handcycling Classes?

The classification system for handcycling groups athletes into five hierarchical classes, based on how much their impairment affects performance. Athletes in class H5, with the least impairments, compete in a kneeling position, while athletes in classes H1 to H4 compete in a recumbent position. This study investigated the average time-trial velocity of athletes in different classes. A total of 1,807 results from 353 athletes who competed at 20 international competitions (2014-2018) were analyzed. Multilevel regression was performed to analyze differences in average velocities between adjacent pairs of classes, while correcting for gender, age, and event distance. The average velocity of adjacent classes was significantly different (p < .01), with higher classes being faster, except for H4 and H5. However, the effect size of the differences between H3 and H4 was smaller (d = 0.12). Hence, results indicated a need for research in evaluating and developing evidence-based classification in handcycling, yielding a class structure with meaningful performance differences between adjacent classes.

The influence of protocol design on the identification of ventilatory thresholds and the attainment of peak physiological responses during synchronous arm crank ergometry in able-bodied participants.

PURPOSE: To examine the effects of stage duration on power output (PO), oxygen uptake (VO2), and heart rate (HR) at peak level and ventilatory thresholds during synchronous arm crank ergometry. METHODS: Nineteen healthy participants completed a ramp, 1-min stepwise, and 3-min stepwise graded arm crank exercise test. PO, VO2, and HR at the first and second ventilatory threshold (VT1, VT2) and peak level were compared among the protocols: a repeated measures analysis of variance was performed to test for systematic differences, while intraclass correlation coefficients (ICC) and Bland-Altman plots were calculated to determine relative and absolute agreement. RESULTS: Systematic differences among the protocols were found for PO at VT1, VT2, and peak level. At peak level, PO differed significantly among all protocols (ramp: 115 ± 37 W; 1-min stepwise: 108 ± 34 W; 3-min stepwise: 94 ± 31 W, p ≤ 0.01). No systematic differences for HR or VO2 were found among the protocols. VT1 and VT2 were identified at 52% and 74% of VO2peak, respectively. The relative agreement among protocols varied (ICC 0.02-0.97), while absolute agreement was low with small-to-large systematic error and large random error. CONCLUSIONS: PO at VTs and peak level was significantly higher in short-stage protocols compared with the 3-min stepwise protocol, whereas HR and VO2 showed no differences. Therefore, training zones based on PO determined in short-stage protocols might give an overestimation. Moreover, due to large random error in HR at VTs between the protocols, it is recommended that different protocols should not be used interchangeably within individuals.

Interrater and intrarater reliability of ventilatory thresholds determined in individuals with spinal cord injury.

STUDY DESIGN: Cross-sectional. OBJECTIVES: Individualized training regimes are often based on ventilatory thresholds (VTs). The objectives were to study: (1) whether VTs during arm ergometry could be determined in individuals with spinal cord injury (SCI), (2) the intrarater and interrater reliability of VT determination. SETTING: University research laboratory. METHODS: Thirty graded arm crank ergometry exercise tests with 1-min increments of recreationally active individuals (tetraplegia (N = 11), paraplegia (N = 19)) were assessed. Two sports physicians assessed all tests blinded, randomly, in two sessions, for VT1 and VT2, resulting in 240 possible VTs. Power output (PO), heart rate (HR), and oxygen uptake (VO2) at each VT were compared between sessions or raters using paired samples t-tests, Wilcoxon signed-rank tests, intraclass correlation coefficients (ICC, relative agreement), and Bland-Altman plots (random error, absolute agreement). RESULTS: Of the 240 VTs, 217 (90%) could be determined. Of the 23 undetermined VTs, 2 (9%) were VT1 and 21 (91%) were VT2; 7 (30%) among individuals with paraplegia, and 16 (70%) among individuals with tetraplegia. For the successfully determined VTs, there were no systematic differences between sessions or raters. Intrarater and interrater ICCs for PO, HR, and VO2 at each VT were high to very high (0.82-1.00). Random error was small to large within raters, and large between raters. CONCLUSIONS: For VTs that could be determined, relative agreement was high to very high, absolute agreement varied. For some individuals, often with tetraplegia, VT determination was not possible, thus other methods should be considered to prescribe exercise intensity.

Adaptive control of dynamic balance in human gait on a split-belt treadmill.

Human bipedal gait is inherently unstable, and staying upright requires adaptive control of dynamic balance. Little is known about adaptive control of dynamic balance in reaction to long-term, continuous perturbations. We examined how dynamic balance control adapts to a continuous perturbation in gait, by letting people walk faster with one leg than the other on a treadmill with two belts (i.e. split-belt walking). In addition, we assessed whether changes in mediolateral dynamic balance control coincide with changes in energy use during split-belt adaptation. In 9 min of split-belt gait, mediolateral margins of stability and mediolateral foot roll-off changed during adaptation to the imposed gait asymmetry, especially on the fast side, and returned to baseline during washout. Interestingly, no changes in mediolateral foot placement (i.e. step width) were found during split-belt adaptation. Furthermore, the initial margin of stability and subsequent mediolateral foot roll-off were strongly coupled to maintain mediolateral dynamic balance throughout the gait cycle. Consistent with previous results, net metabolic power was reduced during split-belt adaptation, but changes in mediolateral dynamic balance control were not correlated with the reduction of net metabolic power during split-belt adaptation. Overall, this study has shown that a complementary mechanism of relative foot positioning and mediolateral foot roll-off adapts to continuously imposed gait asymmetry to maintain dynamic balance in human bipedal gait.