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.

In this cross-sectional study, we evaluated skeletal muscle strength and physical performance (1-min sit-to-stand and short physical performance battery tests), dyspnea, fatigue, and single-breath counting at discharge from a postacute COVID department, in patients recovering from COVID-19 pneumonia who had no locomotor disability before the infection. Quadriceps and biceps were weak in 86% and 73% of the patients, respectively. Maximal voluntary contraction for quadriceps was 18.9 (6.8) kg and for biceps 15.0 (5.5) kg (i.e., 54% and 69% of the predicted normal value, respectively). The number of chair rises in the 1-min sit-to-stand test was 22.1 (7.3 corresponding to 63% of the predicted normal value), whereas the short physical performance battery score was 7.9 (3.3 corresponding to 74% of the predicted normal value). At the end of the 1-min sit-to-stand test, 24% of the patients showed exercise-induced desaturation. The single-breath counting count was 35.4 (12.3) corresponding to 72% that of healthy controls. Mild-to-moderate dyspnea and fatigue were found during activities of daily living (Borg scale score, median value = 0.5 [0–2] and 1 [0–2]) and after the 1-min sit-to-stand (Borg scale score, median value = 3 [2–5] and 1 [0–3]). Significant correlations were observed between muscle strength and physical performance indices (R = 0.31–0.69). The high prevalence of impairment in skeletal muscle strength and physical performance in hospitalized patients recovering from COVID-19 pneumonia without previous locomotor disabilities suggests the need for rehabilitation programs after discharge.

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 (ΔQ_tw,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 ΔQ_tw,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, ΔQ_tw,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.

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 (Q_tw,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 Q_tw,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.