Caregiving strain is associated with cardiac autonomic imbalance in primary oncology caregivers: A cross-sectional analytical study

Objectives: Oncology caregivers often endure a significant amount of psychosocial stress while going through the experience of caregiving for their dependents. Exposure to chronic stress disrupts the cardiac autonomic balance and increases the risk of cardiovascular events. There is a paucity of research on the association between caregiving strain and cardiac autonomic status of primary oncology caregivers. This study aimed to assess the cardiac autonomic balance and its association with the levels of perceived strain and quality of life (QOL) of primary oncology caregivers. Materials and Methods: Forty-six individuals (30 males and 16 females) who have been primary caregivers of patients under the treatment for cancer at the Regional Cancer Centre over the past 3 months–1 year were recruited in this cross-sectional study. Cardiac autonomic status was assessed by heart rate variability (HRV) technique. The level of strain perceived and QOL of the study participants were assessed using the Modified Caregiver Strain Index (MCSI) and Caregiver QOL-Cancer (CQOL-C) questionnaires, respectively. Comparison of study parameters based on MCSI scores (low strain vs. moderate-high strain) was done using the Independent Student’s t-test. Spearman rank correlation coefficient test was performed to assess the correlation between sympathovagal balance (Low frequency [LF]/high frequency [HF]) and other study parameters. Multiple linear regression analysis was performed to predict the LF/HF ratio with independent variables MCSI score and CQOL-C score. P < 0.05 was considered statistically significant. Results: Significantly high blood pressure, LF power, LF nu (LF normalised units) and LF/HF ratio were observed among caregivers with moderate-to-high caregiving strain as compared to those with low strain levels, while significantly low HF nu (HF normalised units) and CQOL-C scores were noted among the moderate-to-high caregiving strain subgroup as compared to the low caregiving strain subgroup. LF/HF ratio revealed a significant positive correlation with the level of caregiving strain (r = 0.563, P < 0.001) and a significant negative correlation with the QOL (r = ?0.489, P = 0.001) of caregivers. However, on regression analysis, the level of caregiving strain was found to be a significant predictor of autonomic dysfunction unlike the caregivers’ QOL. Conclusion: Increased caregiving strain is associated with cardiac autonomic imbalance in primary oncology caregivers.

Muscle force response characteristics of the slipping leg after an unexpected slip / 中国组织工程研究

BACKGROUND: Surface electromyogram signal is often used for qualitative analysis of muscles in the process of autonomic balance recovery after unexpected slips, but there is little research on the response characteristics of muscle force. OBJECTIVE: By the combination of gait analysis and simulation technology to study the muscle force response characteristics of the slipping leg when an unexpected slip of the heel occurs during walking straightly. METHODS: Five healthy subjects were recruited, wearing shoes uniformly, and asked to walk normally on two different straight footpaths (dry oil-free and oil-coated paths). The Vicon motion system and AMTI force measuring platform were used to collect the motion data. Based on the AnyBody Modeling System, a human musculoskeletal model matching with the subjects was established. The model was driven by the motion data, and the data of muscle force were collected and analyzed. RESULTS AND CONCLUSION: The recovery time after an unexpected slip was 15%-45% of a gait cycle and the single support phase was shortened. In the course of autonomic recovery, the muscle strength of the semitendinosus was increased by 25.6% (P < 0.05), and the muscle strength of the short head of biceps femoris increased by 14%. The maximum muscle strength of the medial gastrocnemius increased from 8.4 N/kg to 13.6 N/kg, and that of the lateral gastrocnemius increased by 17.4%. These findings indicate that: in the process of recovering the balance after unexpected slips, the semitendinosus, biceps femoris, gastrocnemius and gastrocnemius produce great muscle force, and meanwhile, the time of single support phase is shortened, so as to quickly transfer the gravity of human body from the sliding leg to the dragging leg and keep the body balance. After the balance recovery from the slip, the human body will make a prediction in the later period of the swing phase to prevent the slip again.

Presence of age- and sex-related differences in heart rate variability despite the maintenance of a suitable level of accelerometer-based physical activity

There is currently a lack of information adjacent on the influence of sex and age in heart rate variability (HRV), adjusted according to accelerometer-based physical activity (PADL). We hypothesized that the effect of sex and age on the HRV should be reduced or absent in individuals with a suitable PADL level. We aim to evaluate the influence of sex and age on HRV, adjusted for the confounding effects of the PADL level. A total of 485 age-stratified subjects (18-39, 40-59, and ≥60 years) underwent HRV analyses at rest and 7-day assessments of accelerometer-based PADL. Multivariate analyses of covariance were done using log-transformed HRV indices as outcomes, age and sex as fixed factors, and PADL, cardiovascular risk, fat body mass, and heart rate (HR) at rest as covariates. Despite the adjustment for directly measured PADL, women had better indices of vagal tone, whereas men had higher sympathetic influence. Also, compared to middle-aged and older adults, younger individuals (ages 18-39 years) presented better HRV. Multiple regression analyses confirmed that age and sex were the main predictors of HRV indices, even after adjusting for PADL directly assessed by triaxial accelerometer and HR. We also observed that the correlation between some HRV indexes and the different indexes of physical activity directly evaluated was significant, but not very consistent. Thus, HRV indices are influenced by age and sex, regardless of accelerometer-based physical activity. Interventions with physical activity and exercise aimed at improving the autonomic modulation of asymptomatic adults should take such differences into account.

Exercise training of dogs with myxomatous valve disease / Treinamento físico de cães com doença mixomatosa valvar

The present study has the objective of evaluating the effects of exercise training, using moderate intensity walking (60 to 80% of maximum heart rate), from 30 to 50 minutes, three times a week, in alternate days, during eight weeks, on heart rate variability in dogs with myxomatous valve disease (MVD). For that, 20 dogs in stages B1 (1), B2 (14) and C2 (5) of MVD (ACVIM classification) were divided into untrained control group (CG, n=9) and training group (TG, n=11), and assessed at baseline (T0), after four (T1) and eight weeks (T2). Only one B1 and five B2 dogs completed the training program. In the time domain, the rMSSD was greater in TG in T1 (155,5+42,07) and T2 (199,8+83,54) than CG (T1:91,17+35,79 and T2:88,17+57,51). In the frequency domain, the variable High Frequency (HF) increased in TG in T1 (30950+25810) and T2 (40300+33870) when compared to the CG (T1:19090+23210 and T2:18810+22200) and within the group TG in T2 in relation to T0 (29340+20950). The proposed walking protocol is concluded to have increased the rMSSD and HF variables in TG, representing an increase of the parasympathetic tonus, justifying the indication of this therapy in B1 and B2 stages of MVD.(AU)

O presente estudo objetivou avaliar o efeito do treinamento físico, utilizando-se a caminhada de moderada intensidade (60 a 80% da frequência cardíaca máxima), por 30 a 50 minutos, três vezes por semana, em dias alternados, durante oito semanas, sobre a variabilidade da frequência cardíaca em cães com degeneração mixomatosa valvar (DMV). Para tanto, 20 cães nos estágios B1 (1), B2 (14) e C2 (5) da DMV (classificação ACVIM) foram divididos em grupo controle não treinado (GC, n=9) e grupo treinamento (GT, n=11) e avaliados no início do estudo (T0), após quatro (T1) e oito semanas (T2). Apenas um cão B1 e cinco B2 completaram o programa de treinamento. No domínio do tempo, a variável rMSSD foi maior no GT em T1 (155,5+42,07) e T2 (199,8+83,54) que o GC (T1:91,17+35,79 e T2:88,17+57,51). No domínio da frequência, a variável High Frequency (HF) aumentou no GT em T1 (30950+25810) e T2 (40300+33870) comparada à do GC (T1:19090+23210 e T2:18810+22200), e dentro do GT no T2 em relação ao T0 (29340+20950). Dessa forma, conclui-se que o protocolo de treinamento proposto aumentou as variáveis rMSSD e HF no GT, representando aumento do tônus parassimpático, o que fundamenta a indicação dessa terapia nos estágios B1 e B2 da DMV.(AU)