Temporal adaptations in generic and population-specific quality of life and falls efficacy in men with recent lower-limb amputations

This study examined the longitudinal changes in generic health-related quality of life (QOL), prosthesis-related QOL, falls efficacy, and walking speed in men with lower-limb amputations up to 6 months following discharge from rehabilitation. Seven male unilateral transtibial amputees completed the Medical Outcomes Study 36-Item Short Form Health Survey, the Prosthesis Evaluation Questionnaire, and the Modified Falls Efficacy Scale at 1, 3, and 6 months postdischarge from rehabilitation. Walking speed was also recorded to objectively assess participants’ mobility. Health-related QOL measures displayed increases, resulting in large effect sizes though not reaching statistical significance. Prosthesis-related QOL measures indicated that scales relating to the participants’ prostheses improved and the support of significant others was the most positively scored variable. Walking speed increased by 0.12 m/ s, although it was not significantly related to indices of QOL or falls efficacy. Falls efficacy did not improve significantly during the study period, although it was strongly related to QOL ( p < 0.05). These results provide a novel insight into how QOL and falls efficacy develop in people with lower-limb amputations, alongside changes in mobility, after discharge from rehabilitation. Further improvements in physical health following discharge may be required to elicit subsequent increases in overall QOL and concurrent improvements in falls efficacy

Biomechanical demands differentiate transitioning vs. continuous stair ascent gait in older women

Background Stair ascent mechanics change with age, but little is known about the differing functional demands of transitioning and continuous ascent. Work investigating the risky transition from gait to ascent is sparse, and the strategies that older adults adopt to achieve these demanding tasks have not been investigated. Methods This study compared the biomechanics of a 2-step transitional (floor-to-step2) and continuous ascent cycle (step1-to-step3) and investigated the role of limb preference in relation to dynamometer-derived knee strength during this transition. A biomechanical analysis of 36 women (60–83 years) ascending a 3-step staircase was conducted. Findings The 2-step transitioning cycle was completed quicker, with a larger range of motion, increased forces, larger knee flexor and dorsiflexor moments and ankle powers (P ≤ 0.05), but reduced hip and knee flexion, smaller hip extensor moments and hip and knee powers compared to continuous ascent. During the transition, 44% of the participants demonstrated a consistent limb preference. In these cases large between-limb extensor strength differences existed (13.8%) and 71% of these participants utilised the stronger limb to execute the 2-step transitional cycle. Interpretation The preferential stronger-limb 2-step transitioning strategy conflicts with previous recommendations of a stronger lead limb for frail/asymmetric populations. Our findings suggest that most healthy older women with large between-limb differences utilise the stronger limb to achieve the considerable propulsion required to redirect momentum during the 2-step transition. The biomechanical demands of ascent, relative to limb strength, can inform exercise programmes by targeting specific muscle groups to help older adults maintain/improve general functioning

Sagittal plane joint kinetics during stair ascent in patients with peripheral arterial disease and intermittent claudication

Stair negotiation poses a substantial physical demand on the musculoskeletal system and this challenging task can place individuals at risk of falls. Peripheral arterial disease (PAD) can cause intermittent claudication (IC) pain in the calf and results in altered gait mechanics during level walking. However, whether those with PAD-IC adopt alternate strategies to climb stairs is unknown. Twelve participants with PAD-IC (six bilateral and six unilateral) and 10 healthy controls were recruited and instructed to ascend a five-step staircase whilst 3D kinematic data of the lower-limbs were recorded synchronously with kinetic data from force plates embedded into the staircase on steps two and three. Limbs from the unilateral group and both limbs from the bilateral claudicants were categorised as claudicating (N = 18), asymptomatic (N = 6) and control (N = 10). Claudicants walked more slowly than healthy controls (trend; P = < 0.066). Both claudicating- and asymptomatic-limb groups had reduced propulsive GRF (P = 0.025 and P = 0.002, respectively) and vertical GRF (P = 0.005 and P = 0.001, respectively) compared to controls. The claudicating-limb group had a reduced knee extensor moment during forward continuance (P = 0.060), ankle angular velocity at peak moment (P = 0.039) and ankle power generation (P = 0.055) compared to the controls. The slower gait speed, irrespective of laterality of symptoms, indicates functional capacity was determined by the limitations of the claudicating limb. Reduced ankle power generation and angular velocity (despite adequate plantarflexor moment) implies velocity-dependent limitations existed in the calf. The lack of notable compensatory strategies indicates reliance on an impaired muscle group to accomplish this potentially hazardous task, highlighting the importance of maintaining plantarflexor strength and power in those with PAD-IC

Biomechanical demands of the 2-step transitional gait cycles linking level gait and stair descent gait in older women

Stair descent is an inherently complex form of locomotion posing a high falls risk for older adults, specifically when negotiating the transitional gait cycles linking level gait and descent. The aim of this study was to enhance our understanding of the biomechanical demands by comparing the demands of these transitions. Lower limb kinematics and kinetics of the 2-step transitions linking level and descent gait at the top (level-to-descent) and the bottom (descent-to-level) of the staircase were quantified in 36 older women with no falls history. Despite undergoing the same vertical displacement (2-steps), the following significant (p<.05) differences were observed during the top transition compared to the bottom transition: reduced step velocity; reduced hip extension and increased ankle dorsiflexion (late stance/pre-swing); reduced ground reaction forces, larger knee extensor moments and powers (absorption; late stance); reduced ankle plantarflexor moments (early and late stance) and increased ankle powers (mid-stance). Top transition biomechanics were similar to those reported previously for continuous descent. Kinetic differences at the knee and ankle signify the contrasting and prominent functions of controlled lowering during the top transition and forward continuance during the bottom transition. The varying musculoskeletal demands encountered during each functional sub-task should be addressed in falls prevention programmes with elderly populations where the greatest clinical impact may be achieved. Knee extensor eccentric power through flexion exercises would facilitate a smooth transition at the top and improving ankle plantarflexion strength during single and double limb stance activities would ease the transition into level gait following continuous descent

Dynamic muscle quality of the plantar flexors is impaired in claudicant patients with peripheral arterial disease and associated with poorer walking endurance

Objectives: Peripheral arterial disease and intermittent claudication (PAD-IC) negatively affects physical activity and function. There is evidence for plantarflexor muscle dysfunction and weakness, however, the extent to which this dysfunction can be attributed to reduced muscle size and/or quality is not yet known. This study investigated whether in vivo plantarflexor muscle quality during static and dynamic contractions are altered by PAD-IC and whether such changes are associated with impaired walking endurance (according to initial and absolute claudication distances). Methods: A total of 22 participants were recruited, consisting of 10 healthy controls and 12 claudicants with occlusion of the superficial femoral artery (seven unilateral and five bilateral). Muscle quality of the combined gastrocnemius muscles during static contractions was calculated by normalising the estimated maximal potential muscle force to the physiological cross-sectional area of both lateral and medial gastrocnemius. Muscle quality during dynamic contractions of the combined plantarflexor muscles was calculated as the ratio of peak voluntary concentric plantarflexor power and the summed volume of lateral and medial gastrocnemius. Results: Dynamic muscle quality was 24% lower in both the claudicating-limb and asymptomatic-limb groups compared to controls (P=.017 and P=.023). The differences were most apparent at the highest contraction velocity (180°/s). Dynamic muscle quality was associated with reduced walking endurance (R=.689, P=.006 and R=.550, P=.042 for initial and absolute claudication distance, respectively). The claudicating-limb group demonstrated a trend towards reduced static muscle quality compared to controls (22%, P=.084). The relative contribution of the soleus muscle to plantarflexion maximum voluntary contraction was significantly higher in both claudicating-limb and asymptomatic-limb groups compared to controls (P=.012 and P=.018). Conclusions: The muscle strength of the plantarflexors in those with PAD-IC appears to be impaired at high contraction velocities. This may be explained by some reduction in gastrocnemii muscle quality and a greater reliance on the prominently type I fibred soleus muscle. The reduced dynamic capability of the plantarflexor muscles was associated with disease severity and walking ability, therefore efforts to improve plantarflexor power through dynamic exercise intervention are vital to maintain functional performance

Forming norms: informing diagnosis and management in sports medicine

Clinicians aim to identify abnormalities, and distinguish harmful from harmless abnormalities. In sports medicine, measures of physical function such as strength, balance and joint flexibility are used as diagnostic tools to identify causes of pain and disability and monitor progression in response to an intervention. Comparing results from clinical measures against ‘normal’ values guides decision-making regarding health outcomes. Understanding ‘normal’ is therefore central to appropriate management of disease and disability. However, ‘normal’ is difficult to clarify and definitions are dependent on context. ‘Normal’ in the clinical setting is best understood as an appropriate state of physical function. Particularly as disease, pain and sickness are expected occurrences of being human, understanding ‘normal’ at each stage of the lifespan is essential to avoid the medicalisation of usual life processes. Clinicians use physical measures to assess physical function and identify disability. Accurate diagnosis hinges on access to ‘normal’ reference values for such measures. However our knowledge of ‘normal’ for many clinical measures in sports medicine is limited. Improved knowledge of normal physical function across the lifespan will assist greatly in the diagnosis and management of pain, disease and disability

Kinematic differences exist between transtibial amputee fallers and non-fallers during downwards step transitioning.

Stair negotiation is biomechanically more challenging than level gait. There are few biomechanical assessments of transtibial amputees descending stairs and none specifically related to falls. Stair descent may elicit more differences than level gait in amputees with and without a previous falls history

Modeling and control of anterior–posterior and medial–lateral sways in standing posture

To study essential anterior–posterior and medial–lateral sways of the stance caused by rotational movements about the ankle and hip joints, a mathematical model is developed for the 3D postural kinematics and dynamics. The model is in the form of nonlinear differential–algebraic equations corresponding to a biomechanical system with holonomic constraints. A nonlinear feedback control law is further derived for stabilizing the upright stance, whilst eliminating internal torques induced by the constraints on postural movements. Numerical simulations of the model parametrized with experimental data of human body segments illustrate the performance of postural balancing with the proposed control

Effect of supervised exercise on physical function and balance in patients with intermittent claudication

Background The aim of the study was to identify whether a standard supervised exercise programme (SEP) for patients with intermittent claudication improved specific measures of functional performance including balance. Methods A prospective observational study was performed at a single tertiary vascular centre. Patients with symptomatic intermittent claudication (Rutherford grades 1–3) were recruited to the study. Participants were assessed at baseline (before SEP) and 3, 6 and 12 months afterwards for markers of lower-limb ischaemia (treadmill walking distance and ankle : brachial pressure index), physical function (6-min walk, Timed Up and Go test, and Short Physical Performance Battery (SPPB) score), balance impairment using computerized dynamic posturography with the Sensory Organization Test (SOT), and quality of life (VascuQoL and Short Form 36). Results Fifty-one participants underwent SEP, which significantly improved initial treadmill walking distance (P = 0·001). Enrolment in a SEP also resulted in improvements in physical function as determined by 6-min maximum walking distance (P = 0·006), SPPB score (P &lt; 0·001), and some domains of both generic (bodily pain, P = 0·025) and disease-specific (social domain, P = 0·039) quality of life. Significant improvements were also noted in balance, as determined by the SOT (P &lt; 0·001). Conclusion Supervised exercise improves both physical function and balance impairment

Influence of pedaling technique on metabolic efficiency in elite cyclists

Our objective was to investigate the influence of pedaling technique on gross efficiency (GE) at various exercise intensities in twelve elite cyclists (V̇O 2max=75.7 ± 6.2 mL•kg -1•min -1). Each cyclist completed a V̇O 2max assessment, skinfold measurements, and an incremental test to determine their lactate threshold (LT) and onset of blood lactate accumulation (OBLA) values. The GE was determined during a three-phase incremental exercise test (below LT, at LT, and at OBLA). We did not find a significant relationship between pedaling technique and GE just below the LT. However, at the LT, there was a significant correlation between GE and mean torque and evenness of torque distribution (r=0.65 and r=0.66, respectively; p < 0.05). At OBLA, as the cadence frequency increased, the GE declined (r=-0.81, p < 0.05). These results suggest that exercise intensity plays an important role in the relationship between pedaling technique and GE