Massimo Venturelli

Six-Month Walking Program Changes Cognitive and ADL Performance in Patients With Alzheimer:

Motor inactivity is typical in the later stages of Alzheimer’s disease although there is evidence that physical exercise can reduce depression and enhance performance of daily activities. The aim of this study was to determine whether a walking program could reduce the functional and cognitive decline of elderly nursing home residents in the later stages of Alzheimer’s disease. A total of 21 patients (84 ± 5 years) were randomly assigned to a walking program (WG) or to a control group (CG). A 6-minute walking test (6WT), the Barthel index of activities of daily living (ADLs), and Mini-Mental State Examination (MMSE) tests were performed before and after 24 weeks of the program. The WG showed significant improvement in the 6WT (20%) and ADLs (23%), while the CG decreased in MMSE (−47%), the WG had a slower decline (−13%). This study indicates that it is possible to stabilize the progressive cognitive dysfunctions in nursing home residents with Alzheimer’s disease through a specific walking program.

Peripheral fatigue limits endurance exercise via a sensory feedback-mediated reduction in spinal motoneuronal output

This study sought to determine whether afferent feedback associated with peripheral muscle fatigue inhibits central motor drive (CMD) and thereby limits endurance exercise performance. On two separate days, eight men performed constant-load, single-leg knee extensor exercise to exhaustion (85% of peak power) with each leg (Leg1 and Leg2). On another day, the performance test was repeated with one leg (Leg1) and consecutively (within 10 s) with the other/contralateral leg (Leg2-post). Exercise-induced quadriceps fatigue was assessed by reductions in potentiated quadriceps twitch-force from pre- to postexercise (ΔQtw,pot) in response to supramaximal magnetic femoral nerve stimulation. The output from spinal motoneurons, estimated from quadriceps electromyography (iEMG), was used to reflect changes in CMD. Rating of perceived exertion (RPE) was recorded during exercise. Time to exhaustion (∼9.3 min) and exercise-induced ΔQtw,pot (∼51%) were similar in Leg1 and Leg2 (P > 0.5). In the consecutive leg trial, endurance performance of the first leg was similar to that observed during the initial trial (∼9.3 min; P = 0.8); however, time to exhaustion of the consecutively exercising contralateral leg (Leg2-post) was shorter than the initial Leg2 trial (4.7 ± 0.6 vs. 9.2 ± 0.4 min; P < 0.01). Additionally, ΔQtw,pot following Leg2-post was less than Leg2 (33 ± 3 vs 52 ± 3%; P < 0.01). Although the slope of iEMG was similar during Leg2 and Leg2-post, end-exercise iEMG following Leg2-post was 26% lower compared with Leg2 (P < 0.05). Despite a similar rate of rise, RPE was consistently ∼28% higher throughout Leg2-post vs. Leg2 (P < 0.05). In conclusion, this study provides evidence that peripheral fatigue and associated afferent feedback limits the development of peripheral fatigue and compromises endurance exercise performance by inhibiting CMD.

Spinal μ-opioid receptor-sensitive lower limb muscle afferents determine corticospinal responsiveness and promote central fatigue in upper limb muscle

We aimed to elucidate the role of group III/IV locomotor muscle afferents in the development of central fatigue and the responsiveness of the corticospinal tract in relation to an unexercised arm muscle. Intrathecal fentanyl, a μ‐opioid receptor agonist, was employed to attenuate afferent feedback from the leg muscles during intense cycling exercise characterized by either no or severe peripheral locomotor muscle fatigue. In the absence of locomotor muscle fatigue, group III/IV‐mediated leg afferent feedback facilitates the responsiveness of the motor pathway to upper limb flexor muscles. By contrast, in the presence of leg fatigue, group III/IV locomotor muscle afferents facilitate supraspinal fatigue in a remote muscle not involved in the exercise and disfacilitate the responsiveness of associated corticospinal projections.

Positive effects of physical training in activity of daily living-dependent older adults.

The goal of this study was to determinate the effects of physical training in older adults with mobility limitations. Thirty frail women (84 ± 6 years) were randomly assigned to a training or control group for 12 weeks of upper body physical training (UBT) performed sitting on wheelchairs. Trained subjects showed a significant improvement in arms strength (+29%), and shoulder flexibility (+10 cm) but did not improve in arms circumference. The activities of daily living (ADLs) were improved (+77%), cognitive function as defined by the Mini-Mental State Examination (MMSE) was maintained in the trained group (+3%) and declined in the control group (−21%). These results demonstrate that UBT in dependent older women with mobility limitations can increase strength and improve ADLs.

Muscle mass and peripheral fatigue: a potential role for afferent feedback?

The voluntary termination of exercise has been hypothesized to occur at a sensory tolerance limit, which is affected by feedback from group III and IV muscle afferents, and is associated with a specific level of peripheral quadriceps fatigue during whole body cycling. Therefore, the purpose of this study was to reduce the amount of muscle mass engaged during dynamic leg exercise to constrain the source of muscle afferent feedback to the central nervous system (CNS) and examine the effect on peripheral quadriceps fatigue.

Group III/IV muscle afferents impair limb blood in patients with chronic heart failure☆ , ☆☆

OBJECTIVEnTo better understand the hemodynamic and autonomic reflex abnormalities in heart-failure patients (HF), we investigated the influence of group III/IV muscle afferents on their cardiovascular response to rhythmic exercise.nnnMETHODSnNine HF-patients (NYHA class-II, mean left ventricular ejection-fraction: 27 ± 3%) performed single leg knee-extensor exercise (25/50/80% peak-workload) under control conditions and with lumbar intrathecal fentanyl impairing μ-opioid receptor-sensitive muscle afferents.nnnRESULTSnCardiac-output (Q) and femoral blood-flow (QL) were determined, and arterial/venous blood samples collected at each workload. Exercise-induced fatigue was estimated via pre/post-exercise changes in quadriceps strength. There were no hemodynamic differences between conditions at rest. During exercise, Q was 8-13% lower with Fentanyl-blockade, secondary to significant reductions in stroke volume and heart rate. Lower norepinephrine spillover during exercise with Fentanyl revealed an attenuated sympathetic outflow that likely contributed to the 25% increase in leg vascular conductance (p<0.05). Despite a concomitant 4% reduction in blood pressure, QL was 10-14% higher and end-exercise fatigue attenuated by 30% with Fentanyl-blockade (p<0.05).nnnCONCLUSION/PRACTICE/IMPLICATIONSnAlthough group III/IV muscle afferents play a critical role for central hemodynamics in HF-patients, it also appears that these sensory neurons cause excessive sympatho-excitation impairing QL which likely contributes to the exercise intolerance in this population.

The role of active muscle mass in determining the magnitude of peripheral fatigue during dynamic exercise

Greater peripheral quadriceps fatigue at the voluntary termination of single-leg knee-extensor exercise (KE), compared with whole-body cycling, has been attributed to confining group III and IV skeletal muscle afferent feedback to a small muscle mass, enabling the central nervous system (CNS) to tolerate greater peripheral fatigue. However, as task specificity and vastly differing systemic challenges may have complicated this interpretation, eight males were studied during constant workload trials to exhaustion at 85% of peak workload during single-leg and double-leg KE. It was hypothesized that because of the smaller muscle mass engaged during single-leg KE, a greater magnitude of peripheral quadriceps fatigue would be present at exhaustion. Vastus lateralis integrated electromyogram (iEMG) signal relative to the first minute of exercise, preexercise to postexercise maximal voluntary contractions (MVCs) of the quadriceps, and twitch-force evoked by supramaximal magnetic femoral nerve stimulation (Qtw,pot) quantified peripheral quadriceps fatigue. Trials performed with single-leg KE (8.1 ± 1.2 min; 45 ± 4 W) resulted in significantly greater peripheral quadriceps fatigue than double-leg KE (10 ± 1.3 min; 83 ± 7 W), as documented by changes in the iEMG signal (147 ± 24 vs. 85 ± 13%), MVC (-25 ± 3 vs. -12 ± 3%), and Qtw,pot (-44 ± 6 vs. -33 ± 7%), for single-leg and double-leg KE, respectively. Therefore, avoiding concerns over task specificity and cardiorespiratory limitations, this study reveals that a reduction in muscle mass permits the development of greater peripheral muscle fatigue and supports the concept that the CNS tolerates a greater magnitude of peripheral fatigue when the source of group III/IV afferent feedback is limited to a small muscle mass.

Impact of body position on central and peripheral hemodynamic contributions to movement-induced hyperemia: implications for rehabilitative medicine.

This study used alterations in body position to identify differences in hemodynamic responses to passive exercise. Central and peripheral hemodynamics were noninvasively measured during 2 min of passive knee extension in 14 subjects, whereas perfusion pressure (PP) was directly measured in a subset of 6 subjects. Movement-induced increases in leg blood flow (LBF) and leg vascular conductance (LVC) were more than twofold greater in the upright compared with supine positions (LBF, supine: 462 ± 6, and upright: 1,084 ± 159 ml/min, P < 0.001; and LVC, supine: 5.3 ± 1.2, and upright: 11.8 ± 2.8 ml·min⁻¹ ·mmHg⁻¹, P < 0.002). The change in heart rate (HR) from baseline to peak was not different between positions (supine: 8 ± 1, and upright: 10 ± 1 beats/min, P = 0.22); however, the elevated HR was maintained for a longer duration when upright. Stroke volume contributed to the increase in cardiac output (CO) during the upright movement only. CO increased in both positions; however, the magnitude and duration of the CO response were greater in the upright position. Mean arterial pressure and PP were higher at baseline and throughout passive movement when upright. Thus exaggerated central hemodynamic responses characterized by an increase in stroke volume and a sustained HR response combined to yield a greater increase in CO during upright movement. This greater central response coupled with the increased PP and LVC explains the twofold greater and more sustained increase in movement-induced hyperemia in the upright compared with supine position and has clinical implications for rehabilitative medicine.

Limitations to exercise in female centenarians: evidence that muscular efficiency tempers the impact of failing lungs

Centenarians are an outstanding model of successful aging, with genetics and healthy lifestyle certainly being key factors responsible for their longevity. Exercise capacity has been identified to play an important role in healthy aging, but a comprehensive assessment of the limitations to maximal exercise in this population is lacking. Following, health histories, lung function, and anthropometric measures, eight female centenarians (98–102xa0years old) and eight young females (18–22xa0years old) performed a series of graded maximal exercise tests on a cycle ergometer that facilitated absolute and relative work rate comparisons. Centenarians revealed a dramatically attenuated lung function, as measured by spirometry (forced expiratory volume in 1xa0s (FEV1/forced vital capacity (FVC), 55u2009±u200910%) compared to the young (FEV1/FVC, 77u2009±u20095%). During exercise, although the centenarians relied heavily on respiratory rate which yielded ∼50% higher dead space/tidal volume, minute ventilation was similar to that of the young at all but maximal exercise, and alveolar PO2 was maintained in both groups. In contrast, peak WR and VO2 were significantly reduced in the centenarians (33u2009±u20094 vs 179u2009±u200924xa0W; 7.5u2009±u20091.2 vs 39.6u2009±u20093.5xa0mlxa0min−1xa0kg−1). Arterial PO2 of the centenarians fell steadily from the normal range of both groups to yield a large A-a gradient (57u2009±u20096xa0mmHg). Metabolic cost of a given absolute work rate was consistently lower, ∼46% less than the young at maximal effort. Centenarians have significant limitations to gas exchange across the lungs during exercise, but this limited oxygen transport is tempered by improved skeletal muscle mechanical efficiency that may play a vital role in maintaining physical function and therefore longevity in this population.

Injury risk factors in young soccer players detected by a multivariate survival model

Soccer is a popular game practiced all around the world by teenagers. However, despite being a relatively safe sport, muscle-strain injuries during competitive matches are common compared to other team-sports. Few studies, to date, have investigated risk factors for soccer injuries using a multivariate survival model (e.g., Cox regression). The aim of this study was to use a multivariate survival model to investigate factors associated with an increased risk of thigh muscle strains, in young soccer players. A multivariate Cox regression was used to evaluate survival probability predictors for thigh muscle strains. 84 young male soccer players (16.4 ± 1.6 years) were followed for a season. Baseline tests were performed for body size, body composition, endurance, flexibility, and jump height from both a static position (SJ), and with a countermovement (CMJ); the percentage difference between the two types of jumps was also calculated (ΔJH). Cox regression result (hazard ratio; C.I. 95%) showed that: previous injuries (2.80; 1.19-6.54), ΔJH (0.79; 0.71-0.87), and stature (1.17; 1.06-1.25) were significantly correlated to thigh-strain survival probability. This study confirms that previous injuries are an important risk factor. However, we also report that a negative ΔJH and an elevated stature increased the probability of thigh strain. This could be explained by poor player coordination, influencing jumping ability, which may be even more evident in tall young players.