Lower limb strength, but not sensorial integration, explains the age-associated postural control impairment.

INTRODUCTION: The aging process leads to functional decline of sensorial organs, muscle mass and strength, as well as the sensorimotor integration, culminating in age-associated postural control impairments. The purpose of this study was to compare the balance, the sensorial integration process and the lower limb strength among three old aged groups. METHODS: Eighty-one community-dwelling healthy old people (58% women), assigned into three age groups [60-69 years (n=30), 70-79 years (n=40), and ≥80 years (n=11)], participated in this study. All participants were submitted to anthropometric and stabilometric evaluation, and carried out a Chair stand test. Stabilometric parameters obtained from time [amplitude displacement of center of pressure (CoP)] and frequency (oscillations of CoP at sub 0.3 Hz and 1-3 Hz bands) domain analysis were used as the indicators of balance performance and sensorial integration, respectively. RESULTS: Our results revealed that the CoP amplitude displacement was significantly greater in the older aged group, without differences in spectral bands, while the performance in the Chair stand test was smaller in the older aged group. CONCLUSION: These data indicate that the age-associated postural control impairment is explained by the lower limb strength declines, but not by the age-associated changes in sensorial integration. LEVEL OF EVIDENCE: III.

Reliability analysis of the heart autonomic control parameters during hemodialysis sessions.

The study of heart autonomic control (HAC) in patients with chronic kidney disease (CKD) undergoing dialysis treatment has been carried out, however, there are no studies reporting the reliability of measurements of HAC parameters involving the mentioned samples and conditions. The reliability of many HAC parameters was evaluated from patients with CKD during two sessions of hemodialysis. The successive R-R intervals were recorded during two sessions of hemodialysis from 14 CKD patients that were undergoing dialysis for at least 6 months and with no history of recurrent hypotensive events. HAC parameters were obtained with time and frequency domain analysis, as well as with nonlinear methods. The reliability was measured with the intraclass correlation coefficient (ICC). The results showed excellent reliability (ICC=0.90-0.98) for most heart rate variability (HRV) parameters, especially the parameters obtained in the time domain [square root of the mean squared differences between successive R-R intervals (RMSSD), percentage of adjacent R-R intervals that differ by more than 50 ms (pNN50), mean of the 5-min standard deviations of R-R intervals (SDNNi), and triangular index] and with non-linear methods [standard deviation of the instantaneous variability beat-to-beat (SD1), standard deviation in long-term continuous R-R intervals (SD2), detrended fluctuation analysis (DFA) α1 and α2, approximate and sample entropies, and correlation dimension (D2): ICC=0.86-0.96]. Among the parameters obtained in the frequency domain (normalized magnitude from the spectrum of low-frequency components (LFnu), normalized magnitude from the spectrum of high-frequency components (HFnu), and LF/HF ratio), the LF/HF ratio showed better reliability (ICC=0.96 vs. ICC=0.70). Measurements of HAC parameters have excellent test-retest reliability for the studied samples and conditions.

El uso de manga de compresión durante 12 horas no es suficiente para mejorar la recuperación muscular del brazo tras el daño inducido por el ejercicio / Twelve hours of a compression sleeve is not enough to improve the muscle recovery of an exercise-damaged upper arm

Objetivo: Evaluar la eficacia de la manga de compresión usada durante un período de tiempo corto (12 h) en la recuperación de los síntomas de daño muscular inducido por el ejercicio de los músculos del brazo. Métodos: En un estudio aleatorizado controlado, 13 hombres jóvenes sanos realizaron un protocolo de ejercicio estandarizado para inducir daño muscular para los flexores del codo y se dividieron inmediatamente en 2 grupos: tratados (n = 7) y control (n = 6). Se tomaron medidas de la fuerza isométrica de flexión del codo, la circunferencia del brazo (CB) y la percepción del dolor muscular antes y 24, 48, 72 y 96 h después del ejercicio, y se utilizaron como criterios de daño muscular inducido por el ejercicio. Comparaciones entre grupos se hicieron para cada variable con un ANOVA de 2 vías (2 grupos × 5 medidas) y con un nivel de significación de p < 0,05. Resultados: Se observó una reducción significativa (p < 0,001) de la fuerza muscular (∼43% y ∼34% para el grupo control y tratados, respectivamente, 24 h después del ejercicio) y un aumento significativo (p < 0,001) en la circunferencia del brazo y dolor muscular (F4,55 = 6,49 para CB y F4,55 = 6,95 para dolor muscular) a lo largo de las medidas después del ejercicio en ambos grupos, sin diferencias significativas entre ellos. Conclusiones: Nuestros resultados, junto con los hallazgos previos, sugieren que el uso de la manga de compresión durante 12 h no es suficiente para mejorar la recuperación de los síntomas de daño muscular inducido por el ejercicio de los músculos del brazo, y para lograr resultados positivos son necesarios largos períodos de compresión

Objective: To assess the efficacy of a compression sleeve worn for a short-time period (12 h) on the recovery from the symptoms of exercise-induced upper arm muscle damage. Methods: A randomized controlled study was conducted on thirteen healthy young men using a standardized and exercise-induced upper arm muscle damage protocol, and they were immediately placed into two groups: TREATED (n = 7) and CONTROL (n = 6). Isometric elbow flexion strength, upper arm circumference, and muscle soreness measurements were taken before and at 24, 48, 72 and 96 h after the damaging exercise, and were used as criteria of exercise-induced muscle damage. Group comparisons were made for each variable using a two-way ANOVA design (2 groups × 5 measurements), and with a significance level of P < .05. Results: A significant impairment (P < .001) was observed in muscle strength (∼ 43% and ∼ 34%, for CONTROL and TREATED groups, respectively, 24 h after exercise), as well as a significant increase (P < .001) in upper arm circumference (UAC) and muscle soreness (F4,55 = 6.49 for UACand F4,55 = 6.95 for muscle soreness) among the measurements after exercise for both groups, with no significant differences between them. Conclusions: These results, together with previous findings, suggest that the use of a compression garment for 12 h is not enough to improve the recovery from exercise- induced muscle damage in the upper arm, and longer periods of compression may be necessary to achieve positive outcomes