Effect of carbohydrate ingestion on exercise performance and carbohydrate metabolism in persons with spinal cord injury.

Carbohydrate ingestion during exercise and as a pre-exercise bolus improves exercise performance in able-bodied athletes. Little is known about the potential for carbohydrate ingestion to improve exercise performance in athletes with spinal cord injury (SCI), nor the potential physiological limitations of such a practice resulting from an SCI. Therefore, this study investigated the effects of carbohydrate ingestion on exercise performance in physically active and athletic persons with SCI. Six participants with complete SCI (neurological level of lesion ranging from C(6) to T(7)) and normal glucose tolerance were studied twice during 60 min of arm cranking at 65% of peak oxygen consumption followed by a 20-min time trial with the ingestion of either a carbohydrate drink (CHO trial: 0.5 g CHO kg(-1) body weight in 500 ml) or placebo (PLA trial) applied in a double-blind counter-balanced manner. The participants with tetraplegia had sufficient neurological function to permit voluntary arm-cranking exercise. There was no difference in time-trial performance between CHO and PLA trials (P > 0.05). The results suggest that carbohydrate ingestion in persons with SCI does not improve exercise performance.

Functional electrical stimulation-supported interval training following sensorimotor-complete spinal cord injury: a case series.

Objective. To investigate the effect of interval training supported by Functional Electrical Stimulation (FES) on ambulation ability in complete spinal cord injury (SCI). Methods. We trained four men with sensorimotor-complete (ASIA A) SCI, who achieved gait through FES of the quadriceps femoris, gluteus maximus, and common peroneal nerve on each side on a motorized treadmill. Training involved progressive interval walking exercise, consisting of periods of activity followed by equal periods of rest, repeated until muscle fatigue. We used time to muscle fatigue during continuous treadmill ambulation as the primary outcome measure. We also recorded the patterns of incremental stimulation for all training and testing sessions. Results. All subjects increased their ambulation capacity; however, the responses varied from subject to subject. Some subjects increased the total distance walked by as much as 300% with progressive improvement over the entire training period; however, others made more modest gains and appeared to reach a performance plateau within a few training sessions. Conclusions. FES-supported interval training offers a useful and effective strategy for strength-endurance improvement in the large muscle groups of the lower limb in motor-complete SCI. We believe that this training protocol offers a viable alternative to that of continuous walking training in people with SCI using FES to aid ambulation.

Efficacy of progressive resistance training on balance performance in older adults : a systematic review of randomized controlled trials.

The serious health, social and economic consequences of falls are well documented. Lower extremity muscle weakness and power as well as balance impairment are major independent intrinsic contributors to falls and amenable to intervention. Progressive resistance training (PRT) is widely accepted as an appropriate modality for treating sarcopenia and has been reported to improve balance. However, other studies affirm no significant effect of PRT on balance. To date, there is no clear, definitive statement or synthesis of studies that has examined the effect of PRT on balance. Therefore, our objective was to systematically review the literature to probe the merit of PRT as a single intervention on balance performance in older adults. We conducted a comprehensive search of major electronic databases to October 2006, with citation searches and bibliographic searches of journal articles and literature/systematic reviews. Two independent reviewers screened for eligibility and assessed the quality of the studies using the Physiotherapy Evidence Database scale for validity assessment. Randomized controlled trials of PRT only, with any balance outcome in participants with a mean age of >/=60 years (individual minimum age >50 years) were included. Trials that contained more than one intervention, providing the PRT and control groups matched the inclusion criteria, were also included. Because of the heterogeneity of interventions and balance outcomes, a meta-analysis was not performed. However, corrected effect sizes with confidence intervals were determined for each study outcome. Twenty-nine studies were compatible with the inclusion/exclusion criteria and were eligible for review. Participants (n = 2174) included healthy, community-dwelling, mobility-limited, frail cohorts and those with chronic comorbidities. Balance outcomes conducted were extensive and were broadly categorized by the authors as: static, dynamic, functional and computerized dynamic posturography. Some studies used more than one balance outcome. The number of balance tests in all totalled 68. Fourteen studies (15 tests representing 22% of all balance tests) reported improvements, significantly greater than controls, in balance performance following PRT. Improvements were not linked to a particular type of balance performance. The inconsistent effect of PRT on balance may be explained by heterogeneity of cohort and balance tests, variability in methodology of the balance test and sample size, inadequate dose of PRT and/or compliance to training, or lack of statistical power. Standardization of balance testing methodology and better reporting of procedures may ensure greater comparability of results in future studies. It is also possible that PRT alone is not a robust intervention for balance control. This is the first systematic synthesis of the literature to examine the effectiveness of PRT alone on balance performance in older adults. The limited evidence presented in currently published data has not consistently shown that the use of PRT in isolation improves balance in this population. However, further research should explore optimal resistance training regimens that: focus on the muscles most pertinent to balance control, best target neuromuscular adaptations that protect against postural challenges and elucidate mechanism(s) by which PRT may affect balance control.

Muscle oxygenation during prolonged electrical stimulation-evoked cycling in paraplegics.

This study investigated cardiorespiratory responses and muscle oxygenation during prolonged electrical stimulation (ES)-evoked leg cycling in individuals with paraplegia (PARA). Four PARA and 6 able-bodied (AB) persons participated in this study. Subjects performed 10 min of passive cycling and 40 min of active cycling (PARA, ES cycling; AB, voluntary cycling) at workloads selected to elicit an equivalent oxygen uptake between groups. Cycling power output, cardiorespiratory responses, mechanical efficiency, and quadriceps muscle oxygenation (measured with near-infrared spectroscopy) were measured over the duration of the exercise. Oxygen uptake was similar in both groups during active cycling (PARA, 737+/-177 mL.min(-1); AB, 840+/-90 mL.min(-1)). The cycling power output for PARA individuals commenced at 8.8 W, but varied considerably over 40 min. PARA individuals demonstrated markedly lower gross mechanical efficiency (approximately 1.3%) during ES cycling compared with AB individuals performing voluntary exercise (approximately 12.6%). During ES cycling, muscle oxygen saturation (SO2) decreased to approximately 72+/-19%, whereas SO2 during volitional cycling was unaltered from resting levels. Muscle oxygenated haemoglobin initially decreased (-23%) during ES cycling, but returned to resting levels after 10 min. Deoxygenated haemoglobin initially rose during the first 5 min of ES cycling, and remained elevated by 28% thereafter. Upon cessation of ES cycling, lower-limb muscle oxygenation increased (+93%), suggesting reactive hyperaemia in PARA individuals after such exercise. During ES cycling, muscle oxygenation followed a different pattern to that observed in AB individuals performing voluntary cycling at an equivalent VO2. Equilibrium between oxygen demand and oxygen delivery was reached during prolonged ES cycling, despite the lack of neural adjustments of leg vasculature in the paralyzed lower limbs.

The placebo effect of ankle taping in ankle instability.

PURPOSE: Recurrence of ankle sprains is common among athletes. Although ankle taping reduces the risk of injury, the mechanism underlying its effectiveness remains unclear. Anecdotal reports suggest a role of the belief among athletes that taping will protect them from injury. That is, taping may have a placebo effect. The purpose of the present study was to determine whether there was a placebo effect with ankle taping in individuals with ankle instability. METHODS: Thirty participants with ankle instability completed a hopping test and a modified star excursion balance test under three conditions: (i) real tape, (ii) placebo tape, and (iii) control (no tape). Participants were blinded to the purpose of the study and were informed that the study aimed to compare two methods of ankle taping referred to as mechanical (real) and proprioceptive (placebo). The order of testing the three conditions and the two functional tests was randomized. RESULTS: There was no significant difference in performance among the three conditions for the hopping test (P = 0.865) or the modified star excursion balance test (P = 0.491). However, a secondary exploratory analysis revealed that participants' perceptions of stability, confidence, and reassurance increased with both real and placebo ankle taping when performing the functional tasks. CONCLUSION: The role of the placebo effect of ankle taping in individuals with ankle instability remains unclear. Clinicians should, therefore, continue to use ankle-taping techniques of known efficacy. They should, however, focus on maximizing patients' beliefs in the efficacy of ankle taping, because its application reassured participants and improved their perceived stability and confidence. The effect of ankle taping on participants' perceptions may contribute to its effectiveness in preventing injury.

Cardiorespiratory fitness and walking ability in subacute stroke patients.

OBJECTIVES: To evaluate the cardiorespiratory fitness of subacute stroke patients and to determine whether reduced fitness is associated with gait performance. DESIGN: Descriptive, cross-sectional study. SETTING: Rehabilitation hospital. PARTICIPANTS: Seventeen patients in an inpatient rehabilitation unit who had mild to moderate gait impairments after a recent (< or =7wk) stroke. All subjects could walk at least 3m alone or with an aid but with no standby assistance. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Peak and submaximal cardiorespiratory responses were measured during semirecumbent leg cycling exercise. Walking velocity and endurance were assessed with 10-m and 6-minute walk tests, respectively. RESULTS: Peak oxygen uptake (Vo(2)peak) was 1.15+/-0.36L/min, which was only 50% of the Vo(2)peak reported in the literature for a healthy, age-matched group. Maximal walking velocity (1.02+/-0.28m/s) and endurance (294.1+/-120.2m) were also approximately 50% of an aged-matched healthy group. Pearson product-moment correlations revealed that 6-minute walking endurance was strongly associated with self-selected walking velocity (R=.91) and measures of peak cardiorespiratory fitness (R=.84). CONCLUSIONS: Cardiorespiratory fitness was markedly impaired within 7 weeks after a stroke. Although muscle weakness and loss of coordination are the primary impairments that affect gait after a stroke, impaired cardiorespiratory fitness may secondarily affect gait performance by limiting walking endurance. To address this secondary impairment, current rehabilitation interventions can incorporate assessment of cardiorespiratory fitness status and aerobic exercise training for persons after stroke.

Onset of electrical stimulation leg cycling in individuals with paraplegia.

PURPOSE: This study investigated cardiovascular and hemodynamic responses during the transition from rest to electrical stimulation-induced leg cycling exercise (ES-LCE) in individuals with chronic paraplegia (PARA). METHODS: Ten PARA (T(4)-T(9); ASIA A) participated in this study. Heart rate (HR), mean arterial pressure (MAP), stroke volume (SV), and cardiac output (Q) were measured on a beat-to-beat basis at rest and during the first 60 s of ES-LCE. RESULTS: PARA exhibited two discrete MAP responses during ES-LCE. Those with high thoracic lesions (HIGH: T(4) -T(6), = 5) responded to ES-LCE with a significant rise in MAP (maxdelta 8.3 +/- 3.6 mm Hg), whereas MAP did not exhibit any sustained change from resting values during ES-LCE in those subjects with lower lesions (LOW: T -T, = 5). In HIGH PARA, the immediate increase in MAP corresponded to a decrease in HR (maxdelta 6.8 +/- 3.1 b x min(-1)), which returned toward resting levels by the end of 60 s. In contrast, for LOW PARA there was no change in HR from resting levels during transition to ES-LCE. In both subgroups, SV and Q were not significantly increased during ES-LCE. CONCLUSION: These results suggest that the on-transient responses of MAP during ES-LCE in HIGH PARA elicited reflex changes in HR via the arterial baroreflex, whereas in LOW PARA, an unchanged HR from rest was likely due to a constant MAP during ES-LCE.

Cardiovascular responses during submaximal electrical stimulation-induced leg cycling in individuals with paraplegia.

This study investigated the cardiovascular responses during electrical stimulation-induced leg cycling (ES-LCE) in people with paraplegia (PARA) compared with voluntary leg cycling (VOL) at similar levels of oxygen uptake in able-bodied (AB) individuals. Six PARA with sensory and motor complete spinal cord lesions (TS-T9) and six AB participated in this study. Oxygen uptake (VO2), stroke volume (SV), heart rate (HR) and cardiac output (Q) were measured at rest and during submaximal, steady-state leg cycling. At the highest power output achieved (9.2 +/- 2.4 W for PARA versus 42.8 +/- 1.0 W for AB), VO2 was augmented above resting levels to 0.75 +/- 0.11 min(-1) in PARA and to 0.74 +/- 0.071 min(-1) in AB. HR and SV were also increased during ES-LCE in PARA (92.1 +/- 8-6 beats min(-1) and 93.9 +/- 11.3 ml bea(-1), respectively) and during VOL in AB (83.9 +/- 9.2 beats min(-1) and 89.7 +/- 9.0 ml beat(-1), respectively). At an equivalent submaximal VO2, HR and SV were not different between the two groups, however, Q was higher in PARA (6.6 +/- 0.7 versus 4.1 +/- 0.9 1 min l(-1) deltaVO2). These data suggest that ES-LCE at relatively low power outputs elicits increases in several cardiovascular variables in PARA. Furthermore, it is possible that ES-LCE leads to a 'hyperkinetic circulation' (a greater Q for a given VO2).