Reliability of recovery heart rate variability measurements as part of the Lamberts Submaximal Cycle Test and the relationship with training status in trained to elite cyclists.

PURPOSE: To determine if post-exercise heart rate variability, in the form of logged transformed root mean square of successive differences of the R-R intervals (LnRMSSD) can be measured reliably during the recovery from a submaximal cycle test and what the relationship of LnRMSSD is with training status of the cyclists. METHODS: Fourteen male cyclists participated in the reliability part for the study, which included performing six Lamberts Submaximal Cycle Test (LSCT), during which recovery LnRMSSD was measured over 30 s (LnRMSSD30 s), 60 s LnRMSSD60 s)and 90 s LnRMSSD90 s). In addition, fifty male and twenty female cyclists completed a peak power output (PPO) test (including VO2peak) and 40 km time trial (40 km TT) before which they performed the LSCT as a standardized warm-up. Relationships between the LnRMSSD and PPO, VO2peak and 40 km TT time were studied. RESULTS: Due to the design of the LSCT, submaximal heart and breathing rate were similar at the end of stage 3 of the LSCT, as well as during the recovery periods. The highest reliability was found in LnRMSSD60 s (ICC: 0.97) with a typical error of the measurement (TEM: 5.8%). In line with this the strongest correlations were found between LnRMSSD60 s and PPO (r = 0.93[male]; 0.85[female]), VO2peak (r = 0.71[male]; 0.63[female];) and 40 km TT (r = - 0.83[male]; - 0.63[female]). CONCLUSIONS: LnRMSSD60 s can be measured reliably after the LSCT and can predict PPO, VO2peak and 40 km TT performance well in trained-to-elite cyclists. These findings suggest that recovery LnRMSSD can potentially play an important role in monitoring and fine-tuning training prescriptions in trained-to-elite cyclists.

Exploring the unmet needs of adults with cerebral palsy living in urban South Africa.

PURPOSE: The investigators aimed to understand the unmet needs of adults with cerebral palsy (CP) living in urban South Africa and to ascertain similarities or differences to typically developing (TD) adults in the same community. MATERIALS AND METHODS: Participants were interviewed with an adapted version of the Southampton Needs Assessment Questionnaire (SNAQ). Non-parametric statistical analysis was utilised for quantitative data and qualitative data were analysed using free coding to identify themes. RESULTS: Thirty adults with CP (median age 34.8 years; GMFCS levels I/II/III/IV/V: n = 6/6/5/7/6; socio-economic status (SES) low/average/high: n = 8/17/5) were matched for gender, age, and SES. Adults with CP reported a higher unemployment rate and lower level of satisfaction with access to health services than TD peers. Core themes identified by the participants with CP that made community participation more difficult were physical capacity, poor access to accommodation, transport and health services, lack of socialising opportunities, poor universal design, and lack of financial independence. CONCLUSIONS: Adults with CP reported experiencing many challenges in their communities. Improved access to health care services and transport, and the universal design of housing and community buildings to accommodate individuals with a disability should be made a priority.Implications for rehabilitationAdults with cerebral palsy (CP) reported that their disability had an impact on their social life, home life, and work life.Accessibility issues have been identified as a major factor affecting adults with CP in a variety of areas, including access to and use of health services, housing, transportation, and community buildings.Adults with CP reported the need for support during the transition to adulthood, especially with developing life skills that will promote living independently in the community as adults with disabilities.

The Influence of a Multistage Mountain-Bike Race on Neuromuscular Activation and Synergies: A Case Study.

INTRODUCTION: This case study aimed to describe potential changes in neuromuscular activation and synergies after an 8-day cross-country mountain-bike stage race. METHODS: A peak power output test was performed 5 days before the race. Two days before the start and after 7 days of racing, the athlete performed a power-based Lamberts Submaximal Cycling Test, including surface electromyography, and completed a Daily Analysis of Life Demands of Athletes questionnaire. Neuromuscular activation, in terms of root mean square, timing (onset-offset) of muscle activation, and synergies, was obtained from electromyography recordings. RESULTS: The athlete reported an increase in symptoms of experienced stress after the stage race on the Daily Analysis of Life Demands of Athletes questionnaire. Both biceps femoris and tibialis anterior muscles showed a reduction in normalized amplitude after the stage race. In addition, the number of synergies that was necessary to describe neuromuscular activation increased from 2 to 3. CONCLUSIONS: In this case study, the increase in synergies suggests that, after the stage race, the athlete showed a more complex muscle-recruitment pattern. This may indicate that muscle coordination can change when muscle fatigue occurs; however, further research is needed to confirm these results in a larger sample.

Muscular Activation Patterns During Exercise on the Treadmill, Stepper, and Elliptical Trainer.

ABSTRACT: Eken, MM, Withers, A, Flanagan, K, Burger, J, Bosch, A, and Lamberts, RP. Muscular activation patterns during exercise on the treadmill, stepper, and elliptical trainer. J Strength Cond Res 36(7): 1847-1852, 2022-Because of the low-impact, the stepper and elliptical trainer are popular alternatives to running when runners sustain running-related injuries. Muscular effort is expected to be lower during exercise on the stepper and elliptical trainer compared with running. The aim of this study was to quantify this by comparing muscular effort when exercising at similar moderate-to-high exercise intensities on a treadmill, stepper, and elliptical trainer. Seventeen well-trained runners (V̇o2max: 53.3 ml·min-1·kg-1 [male: n = 9], 44.8 ml·min-1·kg-1 [female: n = 8]; average peak treadmill running speed: 18.7 km·h-1 [male], 16.3 km·h-1 [female]) performed exercise at submaximal levels (60%-70%-80% of peak workload) on the treadmill, stepper, and elliptical trainer. Peak workload was determined during peak exercise tests on separate days. Surface electromyography was recorded from lower extremity muscles. Root-mean-squared (RMS) values were calculated and compared between exercise modalities and submaximal levels. Significance was set at p < 0.05. Root-mean-squared levels of lower extremity muscles were significantly reduced during exercise on the stepper and elliptical trainer compared with treadmill running (p < 0.05, except for quadriceps (p > 0.05). Overall, similar RMS levels were found on stepper and elliptical trainer (p > 0.05), whereas in several cases higher RMS levels were found on the stepper compared with elliptical trainer (p < 0.05). These findings support clinical expectations that exercise on the stepper and elliptical trainer reduces muscular effort up to 60% compared with (treadmill) running, and therefore can be effective training modalities during rehabilitation from running-related injuries by restricting impact on lower extremities.

Patterns of Athlete Medication Use at the 2018 PyeongChang Paralympic Games: A Descriptive Cohort Study.

OBJECTIVE: Medication use among elite athletes has received growing attention over the past decades. However, only limited studies have focused on para athletes, and trends in medication use among this cohort remain unclear. The aims of this study were (1) to describe the pattern of medication use in elite Paralympic athletes, with a particular focus on analgesics, (2) to analyze whether medications declared by athletes were included in the 2018 World Anti-Doping Agency's prohibited list and monitoring program, (3) to report on a variety of novel supplements, and (4) to review whether athlete analgesic needs will be met by the new Olympic & Paralympic Model Formulary. DESIGN: This is a retrospective, descriptive cohort study. RESULTS: Of all athletes who underwent doping control, 21% declared the use of an analgesic medication. Athletes with limb deficiency and para snowboarders declared the most analgesic medications in their respective categories. It was determined that 84% of the athletes' analgesic medication needs were provided from the new Olympic & Paralympic Model Formulary. CONCLUSIONS: Analgesic use among athletes who participated at the 2018 PyeongChang Winter Paralympics was high. Para snowboarders and athletes with limb deficiency declared the most analgesics. The new Olympic & Paralympic Model Formulary adequately addressed the medication needs of the athletes attending the 2018 games.

Spinal Curvatures, Deformities, and the Level of Disability in People with Bilateral Spastic Cerebral Palsy Living in South Africa; A 6-Year Follow-Up Study During Adulthood.

OBJECTIVE: Determine if spinal curvatures, deformities, as well as level of disability (due to back pain) changes with aging in adults with bilateral spastic cerebral palsy after receiving orthopedic interval surgery approach treatment in childhood. DESIGN: Consecutive case-series SETTING: Urban South Africa PARTICIPANTS: Twenty-seven ambulatory adults with cerebral palsy MAIN OUTCOME MEASURES: Spinal curvatures (scoliosis, thoracic kyphosis and lumbar lordosis) and deformities (spondylolysis and spondylolisthesis) were determined with X-rays, while the level of disability was assessed with the Oswestry Disability Index. RESULTS: The prevalence of spinal abnormalities were: 30% scoliosis (mild: <30°), 0% thoracic hyperkyphosis, 15% lumbar hyperlordosis, 0%; spondylolysis, and 0% spondylolisthesis. No changes in scoliosis and lumbar lordosis angles were observed, while the change in thoracic kyphosis angle was smaller than the minimal clinically important difference and moved closer toward the norm-values for typically developing adults. Level of disability remained similar with 63% reporting minimal disability, 26% moderate disability and 11% severe disability. No associations with spinal curvatures were found. CONCLUSIONS: No clinically meaningful changes in spinal curvatures, deformities and level of disability due to pain were seen during the 6 years follow-up period in adults with cerebral palsy who have been treated with interval surgery approach in childhood.

Physical Activity Levels of Adolescents and Adults With Cerebral Palsy in Urban South Africa.

Background: Research in high income countries shows that people with cerebral palsy (CP) are less physically active than typically developing (TD) peers, but less is known regarding physical activity (PA) in those with CP in low-to-middle income countries. The aim of this study was to determine daily step count and levels of PA in adolescents and adults with CP living in urban South Africa, compared to TD peers, and to determine associations with sex, Gross Motor Function Classification System (GMFCS) level, body mass index and socio-economic status. Materials and Methods: This case-control study included 26 adolescents and 22 adults with CP (GMFCS Level I-V) and matched TD peers (25 and 30, respectively). Participants wore an ActiGraph GT3X for 7 consecutive days to determine step count and time (minutes per hour) spent in PA levels, including sedentary (SED), low physical activity (LPA) and moderate to vigorous physical activity (MVPA). Results: The daily step count and PA levels for ambulant adolescents with CP (GMFCS level I-III) were similar to TD peers, while this was less for adolescents classified in GMFCS level IV-V. Daily step count, SED and MVPA were similar for adults classified in GMFCS level I-II compared to TD adults, while all parameters were lower for adults using assistive devices (GMFCS level III) and non-ambulant adults (GMFCS level IV-V) compared to TD peers. Daily step count and PA levels were inversely associated with GMFCS, while no other associations were found. Conclusion: People with CP who were more mobile dependent (higher GMFCS level) were less active. However, adolescents and adults with CP classified as GMFCS levels I-II living in urban South Africa recorded similar step count and PA levels as their TD peers. This was also the case for adolescents using assistive devices, though not for those in the adult group (GMFCS level III). Furthermore, it was apparent that even the ambulant individuals with CP and TD cohorts were relatively inactive. Intervention programs for CP and TD adolescents should be aimed at finding strategies to keep adolescents physically active well into adulthood, in order to promote physical health, social and emotional well-being and independence.

Adults with spastic diplegic cerebral palsy living in a low-to-middle income country: A six-year follow-up study on pain, functional mobility, activity and participation.

BACKGROUND: Insight into the day-to-day challenges faced by adults living with Cerebral Palsy (CP) in low-to-middle income countries (LMICs) will enable support towards healthy aging in this population. OBJECTIVES: To determine changes in level of pain, functional mobility and accomplishment as well as satisfaction in daily life of ambulant adults with CP living in a LMIC over a six-year period, compared to typically developed (TD) adults. In addition, to determine associations with individual characteristics. METHODS: Twenty-eight adults with CP and spastic diplegia (median [interquartile ranges] age = 39.0 [34.0-45.7] years; Gross Motor Function Classification System level I/II/III: n = 11/12/5) participated in this study, together with 28 matched TD adults. Levels of accomplishment and satisfaction were assessed with the Life-Habits questionnaire, functional mobility was determined with the Functional Mobility Scale and (back, lower and upper limb) pain frequency was gauged with a standardized questionnaire. RESULTS: Life-Habits accomplishment and satisfaction scores of adults with CP remained unchanged during the six-year follow-up, with 79% being independent and 100% satisfied. Functional mobility decreased and related to the total accomplishment score. No change in pain frequency was observed, but adults with CP experienced more pain than their peers. Back pain was significantly associated with the total satisfaction score. CONCLUSIONS: Relative high levels of accomplishment and satisfaction and no change in pain frequency were noted during a six-year follow-up study of adults with CP living in a LMIC. The importance of exercise/rehabilitation programs to reduce pain and maintain functional mobility in persons aging with CP was highlighted.

Physiological and Metabolic Responses to Exercise on Treadmill, Elliptical Trainer, and Stepper: Practical Implications for Training.

Elliptical trainers and steppers are proposed as useful exercise modalities in the rehabilitation of injured runners due to the reduced stress on muscles and joints when compared to running. This study compared the physiological responses to submaximal running (treadmill) with exercise on the elliptical trainer and stepper devices at three submaximal but identical workloads. Authors had 18 trained runners (male/female: N = 9/9, age: mean ± SD = 23 ± 3 years) complete randomized maximal oxygen consumption tests on all three modalities. Submaximal tests of 3 min were performed at 60%, 70%, and 80% of peak workload individually established for each modality. Breath-by-breath oxygen consumption, heart rate, fuel utilization, and energy expenditure were determined. The value of maximal oxygen consumption was not different between treadmill, elliptical, and stepper (49.3 ± 5.3, 48.0 ± 6.6, and 46.7 ± 6.2 ml·min-1·kg-1, respectively). Both physiological measures (oxygen consumption and heart rate) as well as carbohydrate and fat oxidation differed significantly between the different exercise intensities (60%, 70%, and 80%) but did not differ between the treadmill, elliptical trainer, and stepper. Therefore, the elliptical trainer and stepper are suitable substitutes for running during periods when a reduced running load is required, such as during rehabilitation from running-induced injury.

Intraobserver Reliability and Construct Validity of the Squat Test in Children With Cerebral Palsy.

PURPOSE: This study evaluated intraobserver reliability and construct validity of the squat test to assess lower extremity strength in children with cerebral palsy (CP) and spastic diplegia. METHODS: Children with CP performed 2 trials of the squat test and calculated the intraclass correlation coefficient to evaluate intraobserver reliability. Correlations between outcomes of hand-held dynamometry (HHD) of knee extensor strength and an 8-repetition maximum (8RM) leg press test and the squat test were calculated to evaluate construct validity. RESULTS: Excellent intraobserver reliability was observed for the squat test. Correlations between squat test performance and HHD knee extension and 8RM leg press test demonstrated good construct validity. CONCLUSIONS: The squat test is a reliable and valid tool to assess lower extremity strength in children with CP and spastic diplegia. The squat test is inexpensive and less time-consuming, and therefore particularly suitable for clinicians.

The level of accomplishment and satisfaction in activity and participation of adults with cerebral palsy and spastic diplegia.

BACKGROUND: Orthopaedic surgery is commonly performed in children with cerebral palsy (CP) and spastic diplegia to improve functional mobility. However, no research has quantified levels of accomplishment and satisfaction in daily activities and participation long-term after surgery. Therefore, this study aimed to investigate 1) the level of accomplishment and satisfaction of life habits in adults with CP, 2) whether there were differences between Gross Motor Function Classification System (GMFCS) levels, and 3) associations with contextual factors, functional level and frequency of pain. METHODS: Levels of accomplishment and satisfaction in activity and participation were assessed using the Life-Habits 3.1 questionnaire in 30 adults with CP and spastic diplegia who received the first orthopaedic intervention more than 15 years ago (age: median [interquartile range (IQR)] = 27:8 [21:7-33:8] y:mo; GMFCS level I/II/III: n = 15/11/4). GMFCS and Functional Mobility Scale (FMS) assessed mobility over 5 m, 50 m and 500 m. Participants reported frequency of back pain and pain in the lower and upper limb. RESULTS: On average 63% of the participants were independent and faced no difficulties in the accomplishment of all life habits. Difficulties were mostly experienced for 'mobility', 'housing' and 'recreation' (all 61%). Participants were overall satisfied, with lowest scores for 'employment' (13% dissatisfied). Between the GMFCS levels, accomplishment scores of participants with level I were significantly higher than level II. In addition, negative associations were found between accomplishment of life habits and GMFCS level, FMS, and pain on spinal level. CONCLUSION: Levels of accomplishment and satisfaction were relatively high among adults with CP who underwent orthopaedic interventions during childhood. However, negative associations between accomplishment levels and level of functioning and back pain argue for rehabilitation programs specialized on these factors. This information is imperative for physicians and allied health care professionals to guide adults with CP during ageing.

Lower Extremity Strength Profile in Ambulatory Adults with Cerebral Palsy and Spastic Diplegia: Norm Values and Reliability for Hand-Held Dynamometry.

BACKGROUND: The handheld dynamometer (HHD) is a well-accepted tool to assess muscle strength in children with cerebral palsy (CP), though reliability is not tested for adults with CP and no normative data are available. OBJECTIVES: To present strength levels of lower extremity muscle groups and test-retest reliability of HHD measurements in ambulatory adults with CP and typically developed (TD) adults. DESIGN: Case-control study. SETTING: Human motion laboratory. PARTICIPANTS: Fifty-four adults with CP (28 men; Gross Motor Function Classification System [GMFCS] level I/II/III: n = 25/20/9; mean age (SD) = 38 (7) year) and 62 TD adults (31 men; mean age (SD) = 37 (5) year). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE(S): Maximum strength levels were obtained during voluntary isometric contraction of eight lower extremity muscle groups in adults with CP and spastic diplegia and TD adults using HHD. Three trials were performed per muscle group per leg. Test-retest reliability was investigated by calculating intraclass correlation coefficient (ICC), coefficient of variation (CV), and typical error of measurement (TEM). RESULTS: Force and torque levels were significantly lower in all eight lower extremity muscle groups. Excellent ICC levels were observed in TD, GMFCS I and II (>0.90), and moderate to excellent (0.82-0.97) in GMFCS III. CV and TEM were higher in adults with CP compared to TD adults, especially in GMFCS III. LIMITATIONS: No subtypes other than adults with CP and spastic diplegia were included. CONCLUSIONS: Lower extremity strength profiles demonstrate substantial muscle weakness in ambulatory adults with CP compared to TD adults, which highlights the importance to address muscle weakness in this population group. These strength profiles may serve as norm values for clinicians and researchers. In addition, HHD showed to be reliable to assess lower extremity strength in adults with CP.

Quantifying muscle fatigue during walking in people with multiple sclerosis.

BACKGROUND: This study aimed to examine muscle fatigue in lower leg muscles in of people with multiple sclerosis and healthy controls, and whether muscle fatigue coincided with potential changes in gait. METHODS: In this case-control study, people with multiple sclerosis (n = 8; 3male; mean age (SD) = 49.7 (9.6) yr) and age-matched healthy controls (n = 10; 4male; mean age (SD) = 47.4 (8.7) yr) walked on a treadmill for 12-min at self-paced speed. Muscle fatigue was indirectly quantified by a decrease in median frequency and increase in root mean square of surface electromyographic recordings of lower leg muscles. Walking speed, ankle push-off power and net ankle work were calculated from marker positions and force plate data using inverse dynamic calculations. RESULTS: People with multiple sclerosis showed larger decreases in median frequency of soleus (most affected leg: p = 0.003; least affected leg: p = 0.009) and larger increases in root mean square of soleus (most and least affected leg: p = 0.037), gastrocnemius medialis (most affected leg: p = 0.003; least affected leg: p = 0.005) and lateralis (most and least affected leg: p < 0.001) compared to controls. Walking speed (p = 0.001), ankle push-off power (most affected leg: p = 0.018; least affected leg: p = 0.001) and net work around the ankle (most affected leg: p = 0.046; least affected leg: p = 0.001) were lower in people with multiple sclerosis compared to controls, but increased in both groups. INTERPRETATION: The results yield preliminary evidence that soleus muscles of people with multiple sclerosis fatigue during prolonged walking. Changes in electromyography of gastrocnemius muscles could however be related to muscle fatigue, changes in gait or a combination.

The Effectiveness of a Flexible Locked Intramedullary Nail and an Anatomically Contoured Locked Plate to Treat Clavicular Shaft Fractures: A 1-Year Randomized Control Trial.

BACKGROUND: Displaced and shortened clavicular shaft fractures can be treated operatively with intramedullary or extramedullary fixation. The aim of the present study was to compare the union rates and functional outcomes of displaced and/or shortened clavicular shaft fractures treated with a flexible locked intramedullary nail or with an anatomically contoured locked plate. METHODS: Seventy-two patients with acute displaced and/or shortened clavicular shaft fractures underwent randomly assigned management with either an intramedullary locked nail or an anatomically contoured locked plate. The same surgeon performed all surgical procedures, and all patients underwent identical postoperative treatment regimens. Incision length, surgical time, and union rate were recorded, and the functional outcome of the shoulder was assessed with use of the Disabilities of the Arm, Shoulder and Hand (DASH) and Constant Shoulder (CS) scores. Data were analyzed with use of traditional statistical methods as well as Cohen effect sizes, which were based on the minimal clinical important differences. RESULTS: Thirty-seven patients were managed with an anatomically contoured locked plate, and 35 patients were managed with a Sonoma CRx intramedullary flexible locked nail. There were no differences in general patient characteristics, fracture type, or displacement between treatment groups. The nailing group had significantly better outcomes (p < 0.001) than the locked plating group for surgical time (mean and standard deviation [SD], 45 ± 12 compared with 65 ± 21 minutes, respectively) and incision size (mean and SD, 37 ± 9 compared with 116 ± 18 mm). A union rate of 100% was observed in both groups. DASH scores were similar between groups at 1.5, 3, and 6 months, whereas the nailing group had significantly better DASH scores at 12 months (p = 0.022); however, this difference had only a moderate effect size. Overall, individual variation in DASH and CS scores was substantially higher in the plating group compared with the nailing group. CONCLUSIONS: Both the precontoured locked plate and the flexible locked intramedullary nail effectively treated displaced and/or shortened clavicular shaft fractures. Similar outcomes were achieved at 1.5, 3, and 6 months after surgical intervention, and better DASH scores were found in the nailing group at 12 months. Cohen effect sizes suggested that slightly better outcomes were potentially achieved in the nailing group. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Lower limb muscle fatigue during walking in children with cerebral palsy.

AIM: To investigate whether more prominent signs of muscle fatigue occur during self-paced walking in children with cerebral palsy (CP) compared to typically developing peers. METHOD: In this case-control study, 13 children with CP (four males, nine females; mean age [SD] 11y 4mo [3y 8mo]; nine in Gross Motor Function Classification System [GMFCS] level I, three in GMFCS level II, and one in GMFCS level III) and 14 typically developing peers (nine males, five females; mean age [SD] 9y 10mo [1y 10mo]) walked 5 minutes overground at a self-selected walking speed. Electromyography (EMG) median frequency and root mean square (RMS) were identified per gait cycle from EMG recordings of the tibialis anterior, gastrocnemius medialis, soleus, rectus femoris, and semitendinosus. Rate of change in those variables was analysed using mixed linear model analyses. RESULTS: The decrease in EMG median frequency of gastrocnemius medialis and soleus and increase in EMG-RMS of tibialis anterior, gastrocnemius medialis, and soleus were significantly larger in the most affected leg of children with CP compared with typically developing peers. INTERPRETATION: Increased selective muscle fatigue of the lower leg muscles was observed during self-paced walking in children with mild-to-moderate severe CP. This could contribute to and account for limited walking capacity. WHAT THIS PAPER ADDS: Children with cerebral palsy (CP) show more signs of lower leg muscle fatigue than typically developing peers. No signs of muscle fatigue were observed in upper leg muscles of children with CP.

Relations between muscle endurance and subjectively reported fatigue, walking capacity, and participation in mildly affected adolescents with cerebral palsy.

AIM: To investigate the relation between muscle endurance and subjectively reported fatigue, walking capacity, and participation in mildly affected adolescents with cerebral palsy (CP) and peers with typical development. METHOD: In this case-control study, knee extensor muscle endurance was estimated from individual load-endurance curves as the load corresponding to a 15-repetition maximum in 17 adolescents with spastic CP (six males, 11 females; age 12-19y) and 18 adolescents with typical development (eight males, 10 females; age 13-19y). Questionnaires were used to assess subjectively reported fatigue (Pediatric Quality of Life Inventory Multidimensional Fatigue Scale) and participation (Life-Habits questionnaire). Walking capacity was assessed using the 6-minute walk test. Relations were determined using multiple regression analyses. RESULTS: Muscle endurance related significantly to subjectively reported fatigue and walking capacity in adolescents with CP, while no relations were found for adolescents with typical development (subjectively reported fatigue: regression coefficient ß [95% confidence intervals] for CP=23.72 [6.26 to 41.18], for controls=2.72 [-10.26 to 15.69]; walking capacity ß for CP=125m [-87 to 337], for controls=2m [-86 to 89]). The 15-repetition maximum did not relate to participation in adolescents with CP. INTERPRETATION: Subjectively reported fatigue and reduced walking capacity in adolescents with CP are partly caused by lower muscle endurance of knee extensors. Training of muscle endurance might contribute to reducing the experience of fatigue and improving walking capacity. Reduced muscle endurance seems to have no effect on participation.

Coactivation During Dynamometry Testing in Adolescents With Spastic Cerebral Palsy.

BACKGROUND: Dynamometry has been used extensively to measure knee extensor strength in individuals with cerebral palsy (CP). However, increased coactivation can lead to underestimation of knee extensor strength and, therefore, reduce validity of strength measurements. It is yet unknown to what extent coactivation occurs during dynamometry testing and whether coactivation is influenced by severity of CP, load levels, and muscle fatigue. OBJECTIVES: The aims of this study were: (1) to investigate coactivation in adolescents with and without CP during dynamometer tests and (2) to assess the effect of Gross Motor Function Classification System (GMFCS) level, load level, and muscle fatigue on coactivation. DESIGN: A cross-sectional observational design was used. METHOD: Sixteen adolescents with CP (GMFCS levels I and II: n=10/6; age range=13-19 years) and 15 adolescents without CP (n=15; age range=12-19 years) performed maximal isometric contractions (maximal voluntary torque [MVT]) and a series of submaximal dynamic contractions at low (±65% MVT), medium (±75% MVT), and high (±85% MVT) loads until fatigue. A coactivation index (CAI) was calculated for each contraction from surface electromyography recordings from the quadriceps and hamstring muscles. RESULTS: Adolescents with CP classified in GMFCS level II showed significantly higher CAI values than adolescents classified in GMFCS level I and those without CP during maximal and submaximal contractions. No differences were observed among load levels. During the series of fatiguing submaximal contractions, CAI remained constant in both the CP group and the group with typical development (TD), except for adolescents with TD at the low-load condition, which showed a significant decrease. LIMITATIONS: Electromyography tracings were normalized to amplitudes during maximal isometric contractions, whereas previous studies suggested that these types of contractions could not be reliably determined in the CP population. CONCLUSION: Coactivation was higher in adolescents with CP classified in GMFCS level II than in adolescents with TD and those with CP in GMFCS level I at different load levels. Within all groups, coactivation was independent of load level and fatigue. In individuals with CP, coactivation can lead to an underestimation of agonist muscle strength, which should be taken into account while interpreting the results of both maximal and submaximal dynamometer tests.

Assessment of muscle endurance of the knee extensor muscles in adolescents with spastic cerebral palsy using a submaximal repetitions-to-fatigue protocol.

OBJECTIVE: To compare muscle endurance in adolescents with spastic cerebral palsy (CP) with typically developing (TD) peers using a submaximal repetitions-to-fatigue (RTF) protocol. DESIGN: Cross sectional. SETTING: Human motion laboratory. PARTICIPANTS: Adolescents with spastic CP (n=16; Gross Motor Function Classification System levels I or II) and TD adolescents (n=18) within the age range of 12 to 19 years old. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Each participant performed 3 RTF tests at different submaximal loads, ranging from 50% to 90% of their maximal voluntary knee extension torque. The relation between the number of repetitions (repetition maximum [RM]) and imposed submaximal relative (percent of maximal voluntary torque [%MVT]) and absolute (Nm/kg) torque was quantified. To compare adolescents with CP with TD adolescents, a mixed linear model was used to construct load endurance curves. Surface electromyography of quadriceps muscles was measured to assess changes in normalized amplitude and median frequency (MF) as physiological indicators of muscle fatigue. RESULTS: Adolescents with CP showed a larger decrease in %MVT per RM than TD adolescents (P<.05). TD adolescents showed substantial higher absolute (Nm/kg) load endurance curves than adolescents with CP (P<.001), but they did not show a difference in slope. Electromyographic normalized amplitude increased significantly (P<.05) in the quadriceps muscles in all tests for both groups. Electromyographic MF decreased significantly (P<.05) in tests with the low and medium loads. Electromyographic responses did not differ between groups, indicating that similar levels of muscle fatigue were reached. CONCLUSIONS: Adolescents with CP show slightly lower muscle endurance compared with TD adolescents on a submaximal RTF protocol, which is in contrast with earlier findings in a maximal voluntary fatigue protocol. Accordingly, adolescents with CP have a reduced capacity to endure activities at similar relative loads compared with TD adolescents.

Does clinical rehabilitation impose sufficient cardiorespiratory strain to improve aerobic fitness?

OBJECTIVE: To investigate the cardiorespiratory strain experienced by patients over a day and during different types of rehabilitation therapies during a clinical rehabilitation programme. In addition, to investigate the use of the Borg scale as an instrument to monitor exercise intensity. DESIGN: An observational, cross-sectional study. SETTING: Rehabilitation centre in the Netherlands. PARTICIPANTS: Eleven people after stroke (age range 20-71 years), 9 people with a lower limb amputation (age range 21-66 years) and 11 people with a spinal cord injury (age range 28-65 years). All participants were inpatients undergoing clinical rehabilitation. MAIN OUTCOME MEASURES: Frequency distribution of percentage heart rate reserve (%HRR) and length of time heart rate (HR) > 40%HRR over one day, and mean %HRR, length of time HR > 40%HRR and HR > 70%HRR during different types of rehabilitation therapies were compared with the American College of Sports Medicine guidelines for achieving an aerobic training effect. The correlation coefficient between the Borg scale score and %HRR was assessed. RESULTS: Patients' mean HR was 114 min/day (standard deviation 92) > 40%HRR, of which 1 h was spent in therapy. In 5 out of 10 rehabilitation therapies (fitness, hydrotherapy, walking group, wheelchair group and cycling/handbike group) a mean HR > 40%HRR was reached and more than half of the time was spent > 40%HRR. A moderate correlation (R = 0.56) was found between Borg scale score and %HRR. All outcome measures showed large variation between and within patients. CONCLUSION: In general, patients in a clinical rehabilitation programme experience adequate cardiorespiratory strain to potentially induce an aerobic training effect. The large variation in cardiorespiratory strain, however, necessitates individual monitoring to ensure proper exercise intensity. The Borg scale was shown to be of limited value for this monitoring, and therefore the use of HR monitors during rehabilitation should be considered.