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 i...

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.

In humans, the flexor digitorum profundus (FDP), which is a multi‐tendoned muscle, produces forces that flex the four distal interphalangeal joints of the fingers. We determined whether the force associated with activity in a single motor unit in the FDP was confined to a single finger or distributed to more than one finger during a natural grasp. The discharge of single low‐threshold motor units (n= 69) was recorded at sites across the muscle during weak voluntary grasping involving all fingers and spike‐triggered averaging of the forces under each of the finger pads was used to assess the distribution pattern. Spike‐triggered averaging revealed that time‐locked changes in force occurred under the ‘test’ finger (that finger on which the unit principally acted) as well as under the ‘non‐test’ fingers. However, for the index‐, middle‐ and ring‐finger units, the changes in force under non‐test fingers were typically small (< 20 % of those under the test finger). For little‐finger units, the mean changes in force under the adjacent ring finger were large (>50 % of those under the test finger). The distribution of forces by little‐finger units differed significantly from that for each of the other three fingers. Apart from increases in force under non‐test fingers, there was occasional unloading of adjacent fingers (22/267 combinations), usually affecting the index finger. The increases in force under the test finger correlated significantly with the background force for units acting on the middle, ring and little fingers. During a functional grasp, the activity of single units in the FDP allows for a relatively selective control of forces at the tips of the index, middle and ring fingers, but this is limited for little‐finger units.

No abstract

These results demonstrate that during submaximal or maximal exercise there was a greater metabolic stress elicited during ACE+ES-LCE compared with during ACE alone. The higher stroke volume observed during submaximal ACE+ES-LCE, in the absence of any difference in HR, implied a reduced venous pooling and higher cardiac volume loading during ACE+ES-LCE. These results suggest that training incorporating ACE+ES-LCE may be more effective in improving aerobic fitness in people with paraplegia than ACE alone.

The purpose of this study was to investigate the cardiovascular and haemodynamic responses that occur during moderate orthostatic challenge in people with paraplegia, and the effect of electrical stimulation (ES)-induced leg muscle contractions on their responses to orthostatic challenge. Eight males with complete spinal lesions between the 5th and 12th thoracic vertebrae (PARA) and eight able-bodied individuals (AB) volunteered for this study. Changes in heart rate (fc), stroke volume (SV), cardiac output (Qc), mean arterial pressure (MAP), total peripheral resistance (TPR), limb volumes and indices of neural modulation of fc, [parasympathetic (PNS) and sympathetic (SNS) nervous system indicators] were assessed during: (1) supine rest (REST), (2) REST with lower-body negative pressure at -30 torr (LBNP -30, where 1 torr = 133.32 N/m2), and (3) for PARA only, LBNP -30 with ES-induced leg muscle contractions (LBNP + ES). LBNP -30 elicited a decrease in SV (by 23% and 22%), Qc (by 15% and 18%) and the PNS indicator, but an increase in fc (by 10% and 9%), TPR (by 23% and 17%) and calf volume (by 1.51% and 4.04%) in both PARA and AB subjects, respectively. The SNS indicator was increased in the AB group only. Compared to LBNP -30, LBNP + ES increased SV (by 20%) and Qc (by 16%), and decreased TPR (by 12%) in the PARA group. MAP was unchanged from REST during all trials, for both groups. The orthostatic challenge induced by LBNP -30 elicited similar cardiovascular adaptations in PARA and AB subjects. ES-induced muscle contractions during LBNP -30 augmented the cardiovascular responses exhibited by the PARA group, probably via reactivation of the skeletal muscle pump and improved venous return.

This study analysed external power output and physiologic responses in 5 individuals with paraplegia during 40 minutes of electrical stimulation leg cycle exercise. Cycling was performed on a motor-driven isokinetic ergometer that enabled precise determinations of power output. Electrical stimulation was increased to 120-140 mA within the first 5 minutes and remained constant thereafter. Power output increased to 10.7 +/- 3.0 W after 2 minutes, dropped to 5.3 +/- 1.8 W after 6 minutes and subsequently recovered to 8.2 +/- 2.2 and 6.1 +/- 2.3 W after 19.5 and 40 minutes, respectively. Oxygen consumption increased to 0.47 +/- 0.09 l/min after 6 minutes and declined during the second half of the exercise bout. Gross mechanical efficiency after 19.5 minutes was elevated compared with the value after 6 minutes. Heart rate was significantly increased at the end of the trial. The time-dependent variability of power output and physiological responses question the concept of steady state for this form of exercise.

The purpose of this study was to compare the oxygen uptake and heart rate responses during submaximal arm cranking to combined arm cranking+electrical stimulation (ES)-induced leg cycling in individuals with spinal cord injury (SCI). Seven subjects with paraplegia (T 4 ± T 12 ) performed combined arm and leg cycling exercise for 5 min, followed by arm cranking alone at the same power output for a further 5 min. During both exercise conditions, steady state oxygen consumption (VO 2 ), carbon dioxide output (VCO 2 ), expired ventilation (V E ) and heart rate (HR) were determined. The respiratory exchange ratio (RER) and oxygen pulse were calculated from the measured variables. During combined arm+electrical stimulation-induced leg cycling exercise, the VO 2 was 25% higher (1.58 l min 71 vs 1.26 l min 71), but the HR was 13% lower (132 b min 71 vs 149 b min 71 ), than during arm cranking exercise alone. Oxygen pulse and VCO 2 were also signi®cantly higher (by 42% and 25%, respectively) during combined arm+ES-induced leg exercise, but there were no dierences between the two exercise conditions for V E or RER. These data suggest that the absence of the leg`muscle pump' and a reduced venous return of blood to the heart elevate exercise heart rates during submaximal arm cranking. Conversely, combined arm cranking+ES-induced leg cycling exercise provides the body with a greater metabolic stress than arm cranking alone, while reducing the cardiac stress. The mechanism explaining the heart rate response, however, remains unclear, but may have been in¯uenced by the blood pressure variations across the range of lesions. The ®ndings from this study may have implications for the relative bene®t of combined arm+ES-induced leg cycling training for people with paraplegia.