Assessment of Exercise Stroke Volume and Its Prediction From Oxygen Pulse in Paralympic Athletes With Locomotor Impairments: Cardiac Long-Term Adaptations Are Possible

The determinants of cardiac output (CO) during exercise, i.e., stroke volume (SV) and heart rate (HR), could differ in Paralympic athletes (PAthl) with spinal cord injury (SCI) with respect to PAthl with locomotor impairments caused by different health conditions (HCs). The purposes of the present study were the comparisons of two groups of PAthl, one with SCI and the other with either amputation (AMP) or post poliomyelitis syndrome (PM), assessing the (1) peak cardiorespiratory responses and determinants (SV and HR) of CO during maximal and submaximal arm cranking exercise (ACE), respectively; (2) correlations between peak oxygen uptake (VO_2peak) and the highest SV obtained during submaximal exercise; and (3) correlations between oxygen pulse (O₂ pulse, ratio between VO₂ and HR) and both SV and O₂ arterio-venous difference [(a-v)O₂diff]. Each athlete (19 PAthl with SCI, 9 with AMP, and 5 with PM) completed a continuous incremental cardiopulmonary ACE test to volitional fatigue to assess peak responses. In a different session, CO was indirectly measured through carbon dioxide (CO₂) rebreathing method at sub-maximal exercise intensities approximating 30, 50, and 70% of the VO_2peak. There were no significant differences between the PAthl groups in age, anthropometry, and VO_2peak. However, peak HR was significantly lower, and peak O₂ pulse was significantly higher in PAthl with AMP/PM compared to those with SCI. During sub-maximal exercise, PAthl with AMP/PM displayed significantly higher SV values (154.8 ± 17.60 ml) than PAthl with SCI (117.1 ± 24.66 ml). SV correlated significantly with VO_2peak in both PAthl with SCI (R ² = 0.796) and AMP/PM (R ² = 0.824). O₂ pulse correlated significantly with SV in both PAthl with SCI (R ² = 0.888) and AMP/PM (R ² = 0.932) and in the overall sample (R ² = 0.896). No significant correlations were observed between O₂ pulse and (a-v)O₂diff. It was concluded that in PAthl with different HCs: (1) significant differences, as a consequence of the different HC, exist in the determinants of CO at maximal and submaximal ACE; (2) SV is a significant determinant of VO_2peak, suggesting cardiac adaptations possible also in PAthl with SCI; and (3) SV can be predicted from O₂ pulse measurements during submaximal exercise in both groups of PAthl.

Reliability and reactivity of the prefrontal hemodynamic responses in essential hypertension: a functional near infrared spectroscopy study

Prefrontal (PFC) cerebral vasoreactivity may be altered in hypertension but has not been studied during postural change and carbon dioxide (CO2) rebreathing. In this study, a dual procedure of 5% CO2 rebreathing with positional change (standing to supine and reverse) was performed on normotensive (N = 24) and essential hypertensive males (N = 16) (18-55 years) to assess reliability of PFC responses using functional near infrared spectroscopy. The groups (matched on age levels, N = 13) were also compared on their hemodynamic reactivity (change of oxyhemoglobin or total hemoglobin as a function of change in end tidal CO2). Test-retest reliability within one session and 7 days later was moderate to high (intraclass correlation coefficient = .63-.901) in both normotensive and hypertensive groups for all hemodynamic measures; whereas reliability of reactivity measures for oxyhemoglobin and total hemoglobin was moderate (intraclass correlation coefficient = .68-.762). Functional near infrared spectroscopy-measured PFC hemodynamic responses are highly reproducible in normotensive and adult essential hypertensive males.

Electromyographic, cerebral, and muscle hemodynamic responses during intermittent, isometric contractions of the biceps brachii at three submaximal intensities

This study examined the electromyographic, cerebral and muscle hemodynamic responses during intermittent isometric contractions of biceps brachii at 20, 40, and 60% of maximal voluntary contraction (MVC). Eleven volunteers completed 2 min of intermittent isometric contractions (12/min) at an elbow angle of 90° interspersed with 3 min rest between intensities in systematic order. Surface electromyography (EMG) was recorded from the right biceps brachii and near infrared spectroscopy (NIRS) was used to simultaneously measure left prefrontal and right biceps brachii oxyhemoglobin (HbO₂), deoxyhemoglobin (HHb), and total hemoglobin (Hb_tot). Transcranial Doppler ultrasound was used to measure middle cerebral artery velocity (MCAv) bilaterally. Finger photoplethysmography was used to record beat-to-beat blood pressure and heart rate. EMG increased with force output from 20 to 60% MVC (P < 0.05). Cerebral HbO₂ and Hb_tot increased while HHb decreased during contractions with differences observed between 60% vs. 40% and 20% MVC (P < 0.05). Muscle HbO₂ decreased while HHb increased during contractions with differences being observed among intensities (P < 0.05). Muscle Hb_tot increased from rest at 20% MVC (P < 0.05), while no further change was observed at 40 and 60% MVC (P > 0.05). MCAv increased from rest to exercise but was not different among intensities (P > 0.05). Force output correlated with the root mean square EMG and changes in muscle HbO₂ (P < 0.05), but not changes in cerebral HbO₂ (P > 0.05) at all three intensities. Force output declined by 8% from the 1st to the 24th contraction only at 60% MVC and was accompanied by systematic increases in RMS, cerebral HbO₂ and Hb_tot with a leveling off in muscle HbO₂ and Hb_tot. These changes were independent of alterations in mean arterial pressure. Since cerebral blood flow and oxygenation were elevated at 60% MVC, we attribute the development of fatigue to reduced muscle oxygen availability rather than impaired central neuronal activation.

Cerebral and muscle oxygenation changes during static and dynamic knee extensions to voluntary fatigue in healthy men and women: a near infrared spectroscopy study

The aim of the study was to examine the changes in cerebral and muscle blood volume (Cbv, Mbv) and oxygenation (Cox, Mox) during static and dynamic knee extensions to fatigue in men (N=10; 29±9 years) and women (N=14; 27±8 years). After assessment of 1 repetition maximum (1RM) during unilateral knee extensions with the dominant limb, each subject exercised at 50%, 75% and 100% of 1 RM in random order on separate occasions. Simultaneous changes in Cbv, Cox, Mbv and Mox from the contralateral prefrontal lobe and the dominant limb were measured by near infrared spectroscopy. During all three contractions, Cbv and Cox increased while Mbv and Mox decreased until fatigue in both genders. There were no signs of levelling off or decline in Cbv and Cox during any of these contractions, implying that there was no reduction in cerebral neuronal activation. Conversely, there was a rapid decline in Mbv and Mox during the early stages of the contractions, with a plateau or slight increase towards the end. The respective delta values at 50%, 75% and 100% of 1RM for Cbv (0·088 versus 0·062 versus 0·070), Cox (0·042 versus 0·033 versus 0·038), Mbv (-0·225 versus -0·198 versus -0·196), and Mox (-0·169 versus -0·146 versus -0·158) were not significantly different in the total group (N=24). These findings suggest that fatigue during resistance exercise lasting up to 60 s is mediated peripherally because of reduced blood volume and oxygen availability and is independent of the type and intensity of muscle contraction and gender.

Field evaluation of paralympic athletes in selected sports: implications for training

PURPOSE

The purpose of this study was 1) to describe the acute cardiorespiratory and metabolic responses of Paralympic athletes participating in the following five sports: Nordic sit skiing (NS, n = 5), wheelchair distance racing (WR, n = 6), wheelchair basketball (WB, n = 13), wheelchair fencing (WF, n = 6), and wheelchair tennis (WT, n = 4); and 2) to examine the relationship between field test performance and laboratory measures of aerobic fitness of these Paralympic athletes.

METHODS

Each athlete completed an incremental arm cranking exercise test to determine ventilatory threshold (VT) and peak oxygen uptake (VO2peak). Subsequently, field assessments were carried out using a telemetric system to measure the cardiorespiratory responses in their respective sport.

RESULTS

VT and VO2peak (both expressed in milliliters per kilogram per minute) of athletes competing in NS (38.3 +/- 5.76 and 51.0 +/- 6.92 mL x kg(-1) x min(-1)) and WR (35.5 +/- 5.96 and 48.1 +/- 6.35 mL x kg(-1) x min(-1)) were significantly higher (P < 0.05) than those competing in WB (26.0 +/- 2.13 and 36.9 +/- 3.70 mL x kg(-1) x min(-1)), WF (23.2 +/- 3.96 and 34.4 +/- 5.81 mL x kg(-1) x min(-1)), and WT (24.0 +/- 2.30 and 33.1 +/- 2.85 mL x kg(-1) x min(-1)). In the field tests, the average V O2, higher in NS and WR than in WB, WF, and WT, during NS, WR, WB, WF, and WT was 79.4% +/- 3.30%, 84.4% +/- 2.10%, 72.1% +/- 5.72%, 73.0% +/- 3.10%, and 73.0% +/- 1.91%, respectively, of VO2peak. There was a strong linear relationship between VO2 measured during the field tests and VT and VO2peak (R2 = 0.92 in each case).

CONCLUSIONS

Athletes regulated their average work intensity during the field tests in the five Paralympic sports to approximate their individualized VT measured during incremental arm cranking exercise test, and this intensity was within the range recommended by the American College of Sports Medicine to improve cardiorespiratory fitness in well-trained subjects. In addition, performance of Paralympic athletes in these sports was highly dependent upon athletes' aerobic fitness.

Rehabilitation in bariatrics: opportunities for practice and research

PURPOSE

Obesity is associated with a wide range of chronic illnesses and disabilities familiar to rehabilitation researchers and practitioners. Obesity discourse in the area of rehabilitation science and practice is limited.

METHOD

A meeting of rehabilitation researchers, practitioners, industry and decision makers was held for the purpose of identifying research and practice priorities in the area of bariatric rehabilitation.

RESULTS

Areas of common ground in terms of the identification of gaps in research, practice and knowledge about obesity in the context of rehabilitation science were identified. Participants developed a concept for a bariatric rehabilitation treatment and research institute. A commitment to embark on priority action items was made.

CONCLUSIONS

This article describes a process that successfully gathered a diverse group of researchers, clinicians, industries and decision makers for the purpose of collectively advancing the area of bariatric rehabilitation in Canada.

Comparison of a double poling ergometer and field test for elite cross country sit skiers

BACKGROUND

Sport specific ergometers are important for laboratory testing (i.e. peak oxygen consumption (VO(2))) and out of season training.

OBJECTIVES

The purpose of this study was to compare cardiorespiratory variables during exercise on a double poling ergometer to a field test in elite sit skiers.

METHODS

Three male and four female athletes from the Canadian National / Developmental team (17-54 years of age, six with complete paraplegia and one with cerebral palsy) completed a field test and a double poling ergometer protocol separated by at least 24 hours. Both protocols consisted of three maximal trials of skiing of three minutes duration separated by 1.5 minutes of rest. A wireless metabolic system and heart rate monitor were used to measure cardiorespiratory responses [peak heart rate, peak VO(2), and peak respiratory exchange ratio (RER)] during each test. Arterialized blood lactate was measured before the beginning of exercise, after each trial and at 5, 10 and 15 minutes post exercise.

RESULTS

No significant differences existed between the field and ergometer tests for peak oxygen consumption (VO(2)) (field=34.7±5.5 mL·kg-1·min-1 vs. ergometer=33.4±6.9 mL·kg-1·min-1). Significantly higher peak heart rate and RER were found during the ergometer test. Significantly higher lactates were found during the ergometer test after trial 2 and trial 3.

CONCLUSION

The double poling ergometer is similar to a field test for evaluating peak VO(2) in elite cross country sit skiers; however, the ergometer test elicits a higher heart rate and anaerobic response.

Número máximo de repetições em exercícios isotônicos: influência da carga, velocidade e intervalo de recuperação entre séries

INTRODUÇÃO: Pouco se sabe sobre o efeito da velocidade de execução e do intervalo entre séries sobre o desempenho no exercício contra-resistência. OBJETIVO: Comparar o número máximo de repetições até a fadiga voluntária (REPS) na cadeira extensora com o joelho dominante para diferentes cargas, velocidades e intervalos entre séries. MÉTODOS: Nove voluntários (35,8 ± 10,8 anos; 74,2 ± 16,7kg; 171,0 ± 10,0cm) reportaram ao laboratório para determinação de 1RM e REPS em seis situações, determinadas aleatoriamente e separadas por no mínimo 48h: uma série com 60% 1RM a 80°•s¹ e 25°•s-1; uma série com 80% 1RM a 25°•s¹; três séries com 80% 1RM a 80°•s-1 e intervalos de 3 min, 1 min e naquele que permitisse a estabilização da oxigenação muscular (RMox), medida por espectroscopia no infravermelho próximo. RESULTADOS: O teste t dependente mostrou que REPS foi significativamente (p < 0,05) maior na carga leve que na pesada, nas velocidades lenta (leve = 8,8 ± 1,3; pesada = 5,9 ± 0,9) e rápida (leve = 16,3 ± 3,9; pesada = 9,4 ± 1,9), e significativamente maior na velocidade rápida que na lenta, para ambas as cargas. A ANOVA 3x3 não mostrou diferença entre os intervalos na série 1 (3 min = 9,4 ± 1,9; 1 min = 10,8 ± 3,2; RMox = 10,1 ± 3,0), porém, houve diferenças significativas nas séries 2 e 3 entre 3 min (série 2 = 7,0 ± 1,7; série 3 = 6,4 ± 1,3) e 1 min (série 2 = 5,6 ± 1,1; série 3 = 4,8 ± 1,2), mas não entre RMox (série 2 = 6,4 ± 1,7; série 3 = 6,1 ± 1,5) e os demais intervalos. Nos três intervalos, REPS na série 1 foi significativamente maior que nas demais. CONCLUSÕES: O desempenho no exercício contra-resistência é afetado pela carga, velocidade e intervalo entre séries e é independente da recuperação em oxigenação muscular. A prescrição do exercício e a avaliação do desempenho devem levar essas variáveis em consideração frente aos objetivos propostos.

Cerebral oxygenation declines at exercise intensities above the respiratory compensation threshold

During incremental exercise PaCO2 and PETCO2 begin to decline at the respiratory compensation threshold (RCT-GEX). Since PaCO2 alters cerebral blood flow it was hypothesized that there would be a systematic decline in cerebral oxygenation (Cox) measured by near infrared spectroscopy above the RCT (RCT-NIRS). Cardiorespiratory and NIRS responses were simultaneously monitored from the left frontal lobe during incremental exercise in 17 men. All subjects showed a decline in Cox above the RCT-GEX with a 20-40 s delay. Significant differences (P<0.01) were observed between the RCT-GEX and RCT-NIRS for time (9.83 versus 10.39 min), power (198 versus 212 W) and oxygen uptake (2.31 versus 2.43 L min-1). Intra-class correlations for power and absolute VO2 were 0.97 and 0.98, respectively. Bland-Altman analysis revealed no outliers for any of the variables. The results suggested that the decrease in Cox observed above the RCT was most likely due to a reduction in cerebral blood flow mediated by a decline in PaCO2. This decline in Cox could reduce neuronal activation thereby limiting maximal exercise capacity in healthy subjects.

In vivo erector spinae muscle blood volume and oxygenation measures during repetitive incremental lifting and lowering in chronic low back pain participants

STUDY DESIGN

A case control study.

OBJECTIVES

Using metabolic gas analysis and near infrared spectroscopy, a comparison was made between healthy controls and chronic low back pain (LBP) participants on cardiorespiratory, erector spinae muscle blood volume, and oxygenation responses, and these variables were used to determine factors that best predict peak oxygen consumption (VO2peak).

SUMMARY OF BACKGROUND DATA

To date, it is unknown how the cardiorespiratory and erector spinae muscles of chronic LBP persons respond to repetitive incremental lifting and lowering. With the advent of near infrared spectroscopy technology, it is now possible to noninvasively examine erector spinae muscle oxygen supply and utilization in vivo. Thus, by using metabolic gas analysis and near infrared spectroscopy technology simultaneously, it is now possible to compare the cardiorespiratory and erector spinae muscle responses of chronic LBP participants to that of healthy controls (no history of LBP) during incremental work to volitional fatigue.

METHODS

Thirty-four participants with chronic LBP and 34 healthy controls completed the repetitive incremental lifting and lowering (2.25 kg x min) protocol from floor to table (height 76 cm) at 10 lifts . min to voluntary fatigue.

RESULTS

The healthy controls had significantly greater VO2peak (mL x kg x min) and VO2peak (mL x kgLBM x min), peak mass lifted, test duration, and breathing frequency. Furthermore, healthy controls showed significantly greater change in muscle oxygenation and faster one-half recovery times. Multiple regression analysis indicated that approximately 97% of the variance in absolute VO2peak was predicted by cardiorespiratory variables in both groups, while muscle oxygenation aided in predicting VO2peak relative in the LBP participants.

CONCLUSIONS

The results indicated that the chronic LBP participants demonstrated a reduced cardiorespiratory and erector spinae muscle response during repetitive incremental lifting and lowering to volitional fatigue as compared to the healthy controls.

Vastus lateralis oxygenation during prolonged cycling in healthy males

This study examined the relationship between acute cardiorespiratory and muscle oxygenation and blood volume changes during prolonged exercise. Eight healthy male volunteers (mean maximum oxygen uptake ([Formula: see text]O2max) = 41.6 ± 2.4 mL/kg/min) performed 60 min submaximal cycling at 50% [Formula: see text]O2max. Oxygen uptake ([Formula: see text]O2) was measured by indirect spirometry, cardiac output (CO) was estimated using a PortapresTM, and right vastus lateralis oxyhemoglobin/ myoglobin (oxyHb/Mb), deoxyhemoglobin/myoglobin (deoxyHb/Mb), and total hemoglobin/myoglobin (total Hb/Mb) were recorded using near-infrared spectroscopy (NIRS). After 40 min of exercise, there was a significant increase in [Formula: see text]O2 due to a significantly higher arteriovenous oxygen difference ((a - v)O2diff). After 30 min of exercise CO remained unchanged, but there was a significant decrease in stroke volume and a proportionate increase in heart rate, thus indicating the occurrence of cardiovascular drift. During the first few minutes of exercise, there was a decline in oxyHb/Mb and total Hb/Mb, whereas deoxyHb/Mb remained unchanged. Thereafter, oxyHb/Mb and total Hb/Mb increased systematically until the termination of exercise while deoxyHb/Mb declined. After 40 min of exercise, these changes were significantly different from the baseline values. There were no significant correlations between the changes in the NIRS variables and systemic [Formula: see text]O2 or mixed (a - v)O2diff during exercise. These results suggest that factors other than localized changes in muscle oxygenation and blood volume account for the increased [Formula: see text]O2 during prolonged submaximal exercise. Key words: near infrared spectroscopy, cardiovascular drift, systemic oxygen consumption.

Reliability of near-infrared spectroscopy measures of cerebral oxygenation and blood volume during handgrip exercise in nondisabled and traumatic brain-injured subjects

We compared the test-retest reliability of near-infrared spectroscopy (NIRS) measures of cerebral oxygenation and blood volume during a rhythmic handgrip exercise in 13 nondisabled subjects and 25 subjects with moderate to severe traumatic brain injury (TBI). Subjects with TBI (average Glasgow Coma Scale score = 4.2, average time since injury = 21 mo) had completed an acute brain injury rehabilitation program. After 2 min of rest, each subject performed 60 s of maximal rhythmic handgrip contractions with the right hand in two trials 24 to 48 h apart. We used NIRS to measure cerebral oxygenation and blood volume responses from the left prefrontal lobe. Both groups' cerebral oxygenation and blood volume increased during handgrip contractions. The change in cerebral oxygenation was significantly lower in subjects with TBI compared with nondisabled subjects. Intraclass correlations between the two trials for cerebral oxygenation and blood volume were 0.83 and 0.80, respectively, in nondisabled subjects and 0.70 and 0.64, respectively, in subjects with TBI. The findings indicate that NIRS is a reliable noninvasive technique for evaluating cerebral oxygenation and blood volume changes during motor function. NIRS can be useful in monitoring recovery of cerebral oxygenation during rehabilitation of patients with TBI.

Relationship between erector spinae static endurance and muscle oxygenation-blood volume changes in healthy and low back pain subjects

The purposes of this study were to: (1) compare the muscle blood volume (Mbv) and oxygenation (Mox) responses on the right and left side erector spinae during the Biering-Sorensen muscle endurance (BSME) test between healthy, low back pain active (LBP-A) and LBP-sedentary (LBP-S) subjects using near infrared spectroscopy (NIRS), and (2) determine the relationships between the BSME time and Mbv and Mox. Informed consent was obtained from 30 healthy and 30 chronic LBP subjects. The latter group was subdivided into an active (LBP-A; n = 18) and sedentary (LBP-S; n = 12) subgroups based on physical activity patterns. The groups were age and sex matched. The NIRS probes were placed bilaterally on the erector spinae muscle at the level of the third lumbar vertebrae. The testing protocol was: 2-min resting baseline, BSME to voluntary fatigue, and 4-min recovery. During the BSME Mbv immediately increased for approximately 30-60 s, then showed an asymptote, and a steady decline towards the baseline at termination. Mox demonstrated either an initial increase followed by a systematic decrease until the termination of the BSME, or a systematic decrease throughout the BSME until termination. The LBP-S subjects showed a reduced Mox-range and slower Mox (1/2) recovery time on the left side suggesting a reduced aerobic capacity of the erector spinae muscle in this group. Significant correlations were noted between BSME time and the pooled values of Mox-delta and-range only in the LBP-A group. These observations suggest that factors other than erector spinae aerobic capacity can influence BSME performance.

Effects of circuit training on body composition and peak cardiorespiratory responses in patients with moderate to severe traumatic brain injury

OBJECTIVE

To examine the time course of the changes in body composition and peak cardiorespiratory fitness resulting from routine brain injury rehabilitation program (BIRP) activities and circuit training in patients with moderate to severe traumatic brain injury (TBI).

DESIGN

Time-series design spanning 18 weeks. Trials T1 and T2 were completed in weeks 1 and 2, respectively, to establish reliability of the measurements, followed by trial 3 (T3) 4 weeks later to evaluate changes resulting from the BIRP.

SETTING

A BIRP in a community rehabilitation hospital.

PARTICIPANTS

Fourteen inpatients with moderate to severe acquired TBI (Glasgow Coma Scale score, 4.6+/-1.4; time since injury, 17.2+/-17 mo).

INTERVENTIONS

Twelve-week circuit-training program designed to enhance muscular strength and endurance and aerobic fitness. Subjects were tested midway (T4) through the program and at the end (T5) of 12 weeks. The patients completed an average of 32 supervised sessions, each lasting 1 hour.

MAIN OUTCOME MEASURES

Changes in body composition and peak cardiorespiratory responses.

RESULTS

No significant changes were observed in the body mass or percentage body fat during the study. The peak values of power output, oxygen uptake, and ventilation rate increased significantly as a result of training, with no concomitant increases in peak heart rate or blood lactate (T5>T3, T2, T1; P <.05). No significant changes were evident midway through training.

CONCLUSIONS

In a heterogeneous sample of patients with moderate to severe TBI, (1) body composition and peak cardiorespiratory responses remained fairly stable during 6 weeks of BIRP activities, (2) improvements in peak cardiorespiratory fitness required more than 6 weeks of circuit training, and (3) a 12-week course of circuit training without controlling caloric intake was not effective in reducing body weight or percentage body fat.

Reliability of erector spinae oxygenation and blood volume responses using near-infrared spectroscopy in healthy males

The purpose of this investigation was to (1). describe the trends in oxygenation (OXY) and blood volume (BV) of the right and left paraspinal muscles during the Biering-Sorensen muscle endurance (BSME) test using near infrared spectroscopy (NIRS), and (2). assess the test-retest reliability of OXY and BV changes during the BSME in healthy males. Seventeen healthy males [age=28.4 (9.8) years, height=1.75 (0.05) m, body mass=82.7 (9.1) kg; mean (SD)] completed two BSME trials within 1 week. NIRS probes were placed bilaterally at lumbar 3. The test was performed with the subject in the prone position using the following protocol: 2 min baseline, BSME, and 4 min recovery. The delta and range values of OXY and BV were used for analysis. Acceptable intra-class correlations were observed for endurance time and all the NIRS variables at the point of fatigue and at each 10% segment of the BSME during the two trials. Bland-Altman plots confirmed the reproducibility of the bilateral NIRS responses of the paravertebral muscles. The BV responses were more reliable than the OXY responses during the two trials. The OXY and BV responses of the paravertebral muscles during static contractions can be measured reliably using NIRS. Future studies should focus primarily on BV for analysis.

Reliability of peak cardiorespiratory responses in patients with moderate to severe traumatic brain injury

OBJECTIVE

To examine the test-retest reliability of acute physiologic responses in patients with traumatic brain injury (TBI).

DESIGN

Repeated measures within 1 week.

SETTING

Brain injury rehabilitation program and community rehabilitation hospital.

PARTICIPANTS

Thirty-six inpatients or their legal guardians.

INTERVENTIONS

Each patient performed a symptom-limited incremental cycle ergometer test to voluntary fatigue on 2 separate occasions within 1 week.

MAIN OUTCOME MEASURES

Peak values of power output and cardiorespiratory responses measured with a metabolic cart interfaced with an electrocardiogram.

RESULTS

Intraclass correlations between the 2 trials were as follows: power output,.96; absolute oxygen uptake,.98; relative oxygen uptake,.97; heart rate,.82; ventilation rate,.96; and respiratory exchange ratio,.81. Bland-Altman plots showed that all data points were within the 95% confidence limits of the mean value of the 2 trials for each variable.

CONCLUSIONS

The reliability of the peak cardiorespiratory responses during non-weight-bearing exercise was high in patients with TBI in a controlled laboratory setting. Therefore, aerobic exercise programs can be accurately prescribed, and changes resulting from such interventions can be confidently evaluated in this population.

Cardiorespiratory and hemodynamic responses during repetitive incremental lifting and lowering in healthy males and females

The purposes of this study were twofold. First, to evaluate the cardiorespiratory and muscle oxygenation (OXY)/blood volume (BV) responses during repetitive incremental lifting and lowering (RILL) in healthy males and females. Second, to develop a predictive equation for predicting peak aerobic power (VO(2peak)) during RILL from the cardiorespiratory, OXY/BV and body composition variables. Fourteen males and 18 females [mean (SD) for age, height and body mass were: 29.6 (8.2) years; 1.75 (0.07) m; 78.9 (10.4) kg and 23.9 (2.1) years; 1.63 (0.06) m; 62.3 (6.3) kg, respectively] completed a RILL from floor to table height at 10 lifts/min to voluntary fatigue. Cardiorespiratory responses were measured using open circuit spirometry and hemodynamic trends were monitored bilaterally at the third lumbar vertebra via near infrared spectroscopy. Significant sex differences ( p<0.05) were observed for the peak values of oxygen uptake (VO(2peak)), ventilation rate (V(E)), oxygen pulse, BV-max and BV-delta. Erector spinae OXY decreased systematically until VO(2peak )was attained, while BV decreased until approximately 50% of VO(2peak) and then leveled off. Stepwise regression analysis indicated that approximately 75% of the variance in VO(2peak )was predicted from cardiorespiratory, hemodynamic and body composition variables, with the most important predictors for absolute and relative VO(2peak )being V(E) ( r=0.75) and fat mass ( r=-0.63) respectively. Inclusion of left side OXY/BV responses increased the predictability of the common variance in VO(2peak )from 40% to 74%, implying that muscle hemodynamics play an important role in determining VO(2peak )during RILL.

The effects of exercise and education, individually or combined, in women with fibromyalgia

OBJECTIVE

To examine the effectiveness of a supervised aerobic exercise program, a self-management education program, and the combination of exercise and education for women with fibromyalgia (FM).

METHODS

One hundred fifty-two women were randomized into one of 4 groups: exercise-only, education-only, exercise and education, or control. The duration of the study was 12 weeks. All subjects were analyzed at 3 times: before study, immediately upon completion, and 3 months after completion of the intervention program on measures of disability, self-efficacy, fitness, tender point count, and tender point tenderness. Of the 152 women, complete data were available for 95 and 69 who complied with the protocol. In order to determine the group time interaction, a 2 way analysis of variance with repeated measures was used for each measure.

RESULTS

The only significant group time interaction was reported with the compliance analysis for the Self-Efficacy Coping with Other Symptoms subscale and the Six Minute Walk. If the program was followed, the combination of a supervised exercise program and group education provided persons with FM with a better sense of control over their symptoms. Fitness improved in the 2 groups undergoing supervised aerobic exercise programs. However, the improvement in fitness was maintained at followup in the exercise-only group and not the combined group. Conclusion. Subjects receiving the combination of exercise and education and who complied with the treatment protocol improved their perceived ability to cope with other symptoms. In addition, a supervised exercise program increased walking distance at post-test, an increase that was maintained at followup in the exercise-only group. Results demonstrate the challenges with conducting exercise and education studies in persons with FM.

Functional electric stimulation-assisted rowing: Increasing cardiovascular fitness through functional electric stimulation rowing training in persons with spinal cord injury

OBJECTIVES

To assess changes in peak functional aerobic power after a 36-session, progressive functional electric stimulation (FES) rowing hybrid training program for persons with spinal cord injury (SCI) and to examine the safety and acceptability of the ROWSTIM II device as well as the integrity of technical modifications to it.

DESIGN

Repeated-measures training study, quasi-experimental design, within-person data comparison.

SETTING

A university-based recreational physical activity facility for persons with physical disabilities.

PARTICIPANTS

Six persons with level C7-T12 SCI (American Spinal Injury Association classes A-C).

INTERVENTION

Progressive rowing training program, 30 minutes per session, 3 times a week for 12 weeks at 70% to 75% of pretest peak functional aerobic power during FES rowing on an open loop control, FES-assisted rowing machine.

MAIN OUTCOME MEASURES

Total rowing distance, peak functional oxygen consumption, and peak oxygen pulse.

RESULTS

Subjects completed between 22 to 36 sessions. After 3 months of training, rowing distance increased by 25% (P<.02), peak oxygen consumption by 11.2% (P<.001), and peak oxygen pulse by 11.4% (P<.01). Heart rate response to hybrid training did not change at the end of training, although peak heart rate with FES lower-extremity exercise increased significantly from pre- to posttraining (P<.01).

CONCLUSIONS

Pre- and posttraining peak aerobic power values for ROWSTIM II training were comparable to previously reported values for hybrid cycle and upper-extremity exercise. We conclude that FES-assisted rowing is an effective, safe, and well-tolerated training system for persons with SCI.

Predictors of success of intervention programs for persons with fibromyalgia

OBJECTIVE

To determine which sociodemographic, psychological, and behavioral characteristics of persons with fibromyalgia (FM) will predict a positive response to treatment; and to determine if subjects classified according to the Multidimensional Pain Inventory (MPI) responded differently to the interventions.

METHODS

One hundred twenty-eight women with FM underwent baseline testing and were randomized into one of 3 intervention groups or a control group. After the 12 week program, the subjects were reexamined on the same pretest measures. Stepwise regression analyses were conducted to determine the variables that could significantly predict the change in the dependent variables. A reliability of change index was calculated to determine the proportion of responders and nonresponders.

RESULTS

The stepwise regression revealed significant predictor variables for change for all dependent variables except the Fibromyalgia Impact Questionnaire; however, the percentage of the variance in the change scores explained by the independent variables ranged from 4 to 15%. Results from the reliability of change index indicated that no MPI subgroup responded more than another group on any measure.

CONCLUSION

Select sociodemographic and psychosocial variables and type of intervention were not strong predictors of improvement in a variety of measures after a treatment program. The low percentage of explained variance may be due to the heterogeneity of FM. Additionally, the low percentage of responders suggests that current forms of treatment are not effective for a large portion of the FM population.

Physiology of wheelchair racing in athletes with spinal cord injury

Wheelchair racing is one of the most popular sporting activities of individuals with spinal cord injury. Athletes with this impairment have unique changes in metabolic, cardiorespiratory, neuromuscular and thermoregulatory systems, which reduce their overall physiological capacity compared with able-bodied individuals or individuals with other types of impairments. This review on spinal cord injury: presents the International Stoke Mandeville Games Federation classification of wheelchair athletes; describes methods commonly used to characterise anaerobic and aerobic fitness; presents the findings of physiological studies that have evaluated wheelchair racing performance; identifies the risks associated with temperature regulation when competing in wheelchair races; and discusses special conditions that can influence wheelchair racing performance. Currently there is limited research that has examined the relationship between sprint or distance wheelchair racing performance and the anaerobic and aerobic components of physical fitness. Although the descriptive evidence indicates that the profiles of these athletes reflect their training and participation in these specific events, the association between their physiological profiles and real or simulated racing performance is unclear. The generally accepted concept that high values of aerobic and anaerobic power are strongly correlated with endurance and sprint racing performance, respectively, are not necessarily true in this population. Athletes with spinal cord injury have an impaired thermoregulatory capacity, because the compromised autonomic and somatic nervous system functions disrupt control of skin blood flow and sweating below the level of the lesion. As a result, they may be more susceptible to hyperthermia during distance wheelchair racing performance. Wheelchair athletes should follow recommendations advocated for able-bodied individuals to minimise their risks of heat stress during competition. Many athletes with quadriplegia voluntarily induce autonomic dysreflexia (commonly known as boosting) during distance racing events to improve performance. Experimental evidence indicates that boosting can improve performance time by 10% in elite wheelchair marathon racers during simulated racing, as a result of increased oxygen utilisation in the boosted state. However, since boosting can be dangerous to health, the International Paralympic Committee has banned athletes from voluntarily inducing it during competition. The use of anti-gravity suits to increase lower-body positive pressure can increase the peak oxygen uptake, cardiac output and stroke volume. However, the use of abdominal binders does not influence these physiological responses. An effect of either of these techniques on wheelchair racing performance has not been demonstrated.

Oxygenation trends in vastus lateralis muscle during incremental and intense anaerobic cycle exercise in young men and women

The purposes of this study were to compare the acute cardiorespiratory responses and muscle oxygenation trends during incremental cycle exercise to exhaustion with those observed during 30 s and 45 s Wingate tests in healthy men and women, and to examine the relationships between selected variables among these tests. Seventeen healthy junior badminton players, nine men [mean age, height, body mass and maximal oxygen uptake (VO2max) were 15.8 (SD 0.8) years, 1.73 (SD 0.08) m, 65.6 (SD 6.3) kg and 50.6 (SD 6.9) ml x kg(-1) x min(-1) respectively] and eight women [mean age, height, body mass and VO2max were 16.6 (SD 1.0) years, 1.65 (SD 0.03) m, 62.7 (SD 4.5) kg and 42.0 (SD 5.0) ml x kg(-1) x min(-1) respectively] completed a stepwise incremental exercise test to voluntary exhaustion and two Wingate tests lasting 30 s and 45 s in three separate sessions in random order. Cardiorespiratory responses were monitored breath-by-breath using a metabolic cart interfaced with an electrocardiogram. Tissue absorbancy trends were continuously recorded from the right vastus lateralis muscle using dual wavelength near infrared spectroscopy. Oxygen uptake and heart rate were significantly higher during the incremental test when compared to the two Wingate tests in the men and women. However, the oxygen pulse (oxygen utilization per heart beat, i.e., the product of stroke volume and arterio-venous oxygen difference) was not significantly different among the three tests in both sexes. The minimal tissue absorbancy, an index of muscle deoxygenation, was also not significantly different among the three tests in both sexes. Significant relationships were observed for the oxygen uptake (r2=0.72) and oxygen pulse (r2=0.60) between the incremental and 45 s Wingate tests in the sample for both sexes combined. The minimal tissue absorbancy, however, was not significantly related between the two tests. It was concluded that the significantly higher oxygen uptake during the incremental test was due to the higher heart rate because: firstly, oxygen pulse was not significantly different among the three tests, and secondly, peripheral factors, as indicated by the changes in muscle oxygenation, were not significantly different among the three test conditions. Although the peak values of the oxygen pulse during the incremental and 45 s Wingate tests were significantly correlated, the common variance of the minimal tissue absorbancy measurements between these two tests was quite low, suggesting considerable variation in the peripheral contribution during these two tests.

Validity of the baltimore therapeutic equipment work simulator in the measurement of lifting endurance in healthy men

OBJECTIVE

To examine the criterion validity of the Baltimore Therapeutic Equipment (BTE) work simulator by comparing endurance time, oxygen uptake (VO2), and heart rate measured during real and simulated lifting tasks and to derive a regression equation for predicting actual lifting endurance from measurements on the work simulator.

METHOD

Twenty healthy male volunteers repetitively lifted and lowered a load of 40 lb using the BTE work simulator and actual weights at a laboratory workstation. Postures, location, and frequency of lifts were kept constant. Endurance (defined as the time taken for the rating of perceived exertion to increase 2 units on the Borg scale) was measured under both conditions. VO2 and heart rate were also recorded, using standard physiological procedures.

RESULTS

The mean values for endurance time, steady-state VO2, and heart rate were significantly different between the real and simulated tasks (p < .05). Correlation of endurance time between the two tasks was significant (r = .71, p < .05). Step wise regression analysis resulted in the following equation for predicting real endurance from simulated time measurements: predicted real time = .34 simulated time + 3.29; r = .71; SE = 1.00 min.

CONCLUSION

The BTE work simulator tends to overestimate real lifting endurance performance in healthy men. The lower physiological stress during the simulated task suggests a significant difference between the real and simulated loads. Occupational therapists should exercise caution when using the results of the BTE work simulator during functional capacity evaluations.