Change of direction speed (CODS) underpins performance in a wide range of sports but little is known about how stiffness and asymmetries affect CODS. Eighteen healthy males performed unilateral drop ...jumps to determine vertical, ankle, knee and hip stiffness, and a CODS test to evaluate left and right leg cutting performance during which ground reaction force data were sampled. A step-wise regression analysis was performed to ascertain the determinants of CODS time. A two-variable regression model explained 63% (R
2
= 0.63; P = 0.001) of CODS performance. The model included the mean vertical stiffness and jump height asymmetry determined during the drop jump. Faster athletes (n = 9) exhibited greater vertical stiffness (F = 12.40; P = 0.001) and less asymmetry in drop jump height (F = 6.02; P = 0.026) than slower athletes (n = 9); effect sizes were both "large" in magnitude. Results suggest that overall vertical stiffness and drop jump height asymmetry are the strongest predictors of CODS in a healthy, non-athletic population.
Abstract
Background
People with chronic kidney disease (CKD) report high levels of physical inactivity, a major modifiable risk factor for morbidity and mortality. Understanding the biological, ...psychosocial and demographic causes of physical activity behaviour is essential for the development and improvement of potential health interventions and promotional initiatives. This study investigated the prevalence of physical inactivity and determined individual correlates of this behaviour in a large sample of patients across the spectrum of kidney disease.
Methods
A total of 5656 people across all stages of CKD (1–2, 3, 4–5, haemodialysis, peritoneal dialysis and renal transplant recipients) were recruited from 17 sites in England from July 2012 to October 2018. Physical activity was evaluated using the General Practice Physical Activity Questionnaire. Self-reported cardiorespiratory fitness, self-efficacy and stage of change were also assessed. Binominal generalized linear mutually adjusted models were conducted to explore the associations between physical activity and correlate variables. This cross-sectional observational multi-centre study was registered retrospectively as ISRCTN87066351 (October 2015).
Results
The prevalence of physical activity (6–34%) was low and worsened with disease progression. Being older, female and having a greater number of comorbidities were associated with greater odds of being physically inactive. Higher haemoglobin, cardiorespiratory fitness and self-efficacy levels were associated with increased odds of being active. Neither ethnicity nor smoking history had any effect on physical activity.
Conclusions
Levels of physical inactivity are high across all stages of CKD. The identification of stage-specific correlates of physical activity may help to prioritize factors in target groups of kidney patients and improve the development and improvement of public health interventions.
Chronic kidney disease (CKD) is characterized by adverse changes in body composition, which are associated with poor clinical outcome and physical functioning. Whilst size is the key for muscle ...functioning, changes in muscle quality specifically increase in intramuscular fat infiltration (myosteatosis) and fibrosis (myofibrosis) may be important. We investigated the role of muscle quality and size on physical performance in non-dialysis CKD patients.
Ultrasound (US) images of the rectus femoris (RF) were obtained. Muscle quality was assessed using echo intensity (EI), and qualitatively using Heckmatt's visual rating scale. Muscle size was obtained from RF cross-sectional area (RF-CSA). Physical function was measured by the sit-to-stand-60s (STS-60) test, incremental (ISWT) and endurance shuttle walk tests, lower limb and handgrip strength, exercise capacity (VO2peak) and gait speed.
A total of 61 patients (58.5 ± 14.9 years, 46% female, estimated glomerular filtration rate 31.1 ± 20.2 mL/min/1.73 m2) were recruited. Lower EI (i.e. higher muscle quality) was significantly associated with better physical performance STS-60 (r = 0.363) and ISWT (r = 0.320), and greater VO2peak (r = 0.439). The qualitative rating was closely associated with EI values, and significant differences in function were seen between the ratings. RF-CSA was a better predictor of performance than muscle quality.
In CKD, increased US-derived EI was negatively correlated with physical performance; however, muscle size remains the largest predictor of physical function. Therefore, in addition to the loss of muscle size, muscle quality should be considered an important factor that may contribute to deficits in mobility and function in CKD. Interventions such as exercise could improve both of these factors.
Abstract The global energy budget is pivotal to understanding planetary evolution and climate behaviors. Assessing the energy budget of giant planets, particularly those with large seasonal cycles, ...however, remains a challenge without long-term observations. Evolution models of Saturn cannot explain its estimated Bond albedo and internal heat flux, mainly because previous estimates were based on limited observations. Here, we analyze the long-term observations recorded by the Cassini spacecraft and find notably higher Bond albedo (0.41 ± 0.02) and internal heat flux (2.84 ± 0.20 Wm −2 ) values than previous estimates. Furthermore, Saturn’s global energy budget is not in a steady state and exhibits significant dynamical imbalances. The global radiant energy deficit at the top of the atmosphere, indicative of the planetary cooling of Saturn, reveals remarkable seasonal fluctuations with a magnitude of 16.0 ± 4.2%. Further analysis of the energy budget of the upper atmosphere including the internal heat suggests seasonal energy imbalances at both global and hemispheric scales, contributing to the development of giant convective storms on Saturn. Similar seasonal variabilities of planetary cooling and energy imbalance exist in other giant planets within and beyond the Solar System, a prospect currently overlooked in existing evolutional and atmospheric models.
Renal transplant recipients (RTRs) and patients with nondialysis chronic kidney disease display elevated circulating microparticle (MP) counts, while RTRs display immunosuppression-induced infection ...susceptibility. The impact of aerobic exercise on circulating immune cells and MPs is unknown in RTRs. Fifteen RTRs age: 52.8 ± 14.5 yr, estimated glomerular filtration rate (eGFR): 51.7 ± 19.8 mL·min
·1.73 m
(mean ± SD) and 16 patients with nondialysis chronic kidney disease (age: 54.8 ± 16.3 yr, eGFR: 61.9 ± 21.0 mL·min
·1.73 m
, acting as a uremic control group), and 16 healthy control participants (age: 52.2 ± 16.2 yr, eGFR: 85.6 ± 6.1 mL·min
·1.73 m
) completed 20 min of walking at 60-70% peak O
consumption. Venous blood samples were taken preexercise, postexercise, and 1 h postexercise. Leukocytes and MPs were assessed using flow cytometry. Exercise increased classical (
= 0.001) and nonclassical (
= 0.002) monocyte subset proportions but decreased the intermediate subset (
< 0.001) in all groups. Exercise also decreased the percentage of platelet-derived MPs that expressed tissue factor in all groups (
= 0.01), although no other exercise-dependent effects were observed. The exercise-induced reduction in intermediate monocyte percentage suggests an anti-inflammatory effect, although this requires further investigation. The reduction in the percentage of tissue factor-positive platelet-derived MPs suggests reduced prothrombotic potential, although further functional assays are required. Exercise did not cause aberrant immune cell activation, suggesting its safety from an immunological standpoint (ISRCTN38935454).
Protein-energy wasting is highly prevalent in people with end-stage kidney disease receiving regular hemodialysis. Currently, it is unclear what the optimal nutritional recommendations are, which is ...further complicated by differences in dietary patterns between countries. The aim of the study was to understand and compare dietary intake between individuals receiving hemodialysis in Leicester, UK and Nantong, China.
The study assessed 40 UK and 44 Chinese participants' dietary intake over a period of 14 days using 24-hour diet recall interviews. Nutritional blood parameters were obtained from medical records. Food consumed by participants in the UK and China was analyzed using the Nutritics and Nutrition calculator to quantify nutritional intake.
Energy and protein intake were comparable between UK and Chinese participants, but with both below the recommended daily intake. Potassium intake was higher in UK participants compared to Chinese participants (2,115 888 versus 1,159 861 mg/d; P < .001), as was calcium (618 257 versus 360 312 mg/d; P < .001) and phosphate intake (927 485 versus 697 434 mg/d; P = .007). Vitamin C intake was lower in UK participants compared to their Chinese counterparts (39 51 versus 64 42 mg/d; P = .024). Data are reported here as median (interquartile range).
Both UK and Chinese hemodialysis participants have insufficient protein and energy in their diet. New strategies are required to increase protein and energy intakes. All participants had inadequate daily intake of vitamins C and D; there may well be a role in the oral supplementation of these vitamins, and further studies are urgently needed.
Kidney transplant recipients (KTRs) exhibit unique elevated inflammation, impaired immune function, and increased cardiovascular risk. Although exercise reduces cardiovascular risk, there is limited ...research on this population, particularly surrounding novel high-intensity interval training (HIIT). The purpose of this pilot study was to determine the feasibility and acceptability of HIIT in KTRs.
Twenty KTRs (male 14; eGFR 58±19 mL/min/1.73 m
; age 49±11 years) were randomised and completed one of three trials: HIIT A (4-, 2-, and 1-min intervals; 80-90% watts at V̇O
), HIITB (4×4 min intervals; 80-90% V̇O
) or MICT (~40 min; 50-60% V̇O
) for 24 supervised sessions on a stationary bike (approx. 3x/week over 8 weeks) and followed up for 3 months. Feasibility was assessed by recruitment, retention, and intervention acceptability and adherence.
Twenty participants completed the intervention, and 8 of whom achieved the required intensity based on power output (HIIT A, 0/6 0%; HIITB, 3/8 38%; MICT, 5/6 83%). Participants completed 92% of the 24 sessions with 105 cancelled and rescheduled sessions and an average of 10 weeks to complete the intervention. Pre-intervention versus post-intervention V̇O
(mL/kg
/min
) was 24.28±4.91 versus 27.06±4.82 in HIITA, 24.65±7.67 versus 27.48±8.23 in HIIT B, and 29.33±9.04 versus 33.05±9.90 in MICT. No adverse events were reported.
This is the first study to report the feasibility of HIIT in KTRs. Although participants struggled to achieve the required intensity (power), this study highlights the potential that exercise has to reduce cardiovascular risk in KTRs. HIIT and MICT performed on a cycle, with some modification, could be considered safe and feasible in KTRs. Larger scale trials are required to assess the efficacy of HIIT in KTRs and in particular identify the most appropriate intensities, recovery periods, and session duration. Some flexibility in delivery, such as incorporating home-based sessions, may need to be considered to improve recruitment and retention.
ISRCTN, ISRCTN17122775 . Registered on 30 January 2017.
Those living with kidney disease (KD) report extensive symptom burden. However, research into how symptoms change across stages is limited. The aims of this study were to 1) describe symptom burden ...across disease trajectory, and 2) to explore whether symptom burden is unique to KD when compared to a non-KD population.
Participants aged > 18 years with a known diagnosis of KD (including haemodialysis (HD) and peritoneal dialysis (PD)) and with a kidney transplant) completed the Leicester Kidney Symptom Questionnaire (KSQ). A non-KD group was recruited as a comparative group. Multinominal logistic regression modelling was used to test the difference in likelihood of those with KD reporting each symptom.
In total, 2279 participants were included in the final analysis (age 56.0 (17.8) years, 48% male). The main findings can be summarised as: 1) the number of symptoms increases as KD severity progresses; 2) those with early stage KD have a comparable number of symptoms to those without KD; 3) apart from those receiving PD, the most frequently reported symptom across every other group, including the non-KD group, was 'feeling tired'; and 4) being female independently increased the likelihood of reporting more symptoms.
Our findings have important implications for patients with KD. We have shown that high symptom burden is prevalent across the spectrum of disease, and present novel data on symptoms experienced in those without KD. Symptoms requiring the most immediate attention given their high prevalence may include pain and fatigue.
The study was registered prospectively as ISRCTN11596292 .
Patients with chronic kidney disease (CKD) have aberrant changes in body composition, including low skeletal muscle mass, a feature of "sarcopenia." The measurement of the (quadriceps) rectus femoris ...(RF) cross-sectional area (CSA) is widely used as a marker of muscle size. Cutoff values are needed to help discriminate the condition of an individual's muscle (eg, presence of sarcopenia) quickly and accurately. This could help distinguish those at greater risk and aid in targeted treatment programs.
Transverse images of the RF were obtained by B-mode 2-dimensional ultrasound imaging. Sarcopenic levels of muscle mass were defined by established criteria (1, appendicular skeletal muscle mass ASM; 2, ASM/height
; and 3, ASM/body mass index) based on the ASM and total muscle mass measured by a bioelectrical impedance analysis. The discriminative power of RF-CSA was assessed by receiver operating characteristic curves, and optimal cutoffs were determined by the maximum Youden index (J).
One hundred thirteen patients with CKD (mean age SD, 62.0 14.1 years; 48% male; estimated glomerular filtration rate, 38.0 21.5 mL/min/1.73m
) were included. The RF-CSA was a moderate predictor of ASM (R
= 0.426; P < .001) and total muscle mass (R
= 0.438; P < .001). With a maximum J of 0.47, in male patients, an RF-CSA cutoff of less than 8.9 cm
was deemed an appropriate cutoff for detecting sarcopenic muscle mass. In female patients, an RF-CSA cutoff of less than 5.7 cm
was calculated on the basis of ASM/height
(J = 0.71).
Ultrasound may provide a low-cost and simple means to diagnose sarcopenia in patients with CKD. This would allow for early management and timely intervention to help mitigate the effects in this group.
Purpose
Chronic kidney disease (CKD) is characterised by poor physical function. A possible factor may be aberrant changes to balance and postural stability (i.e. ability to maintain centre of ...pressure (COP)). Previous research has exclusively focused on patients undergoing renal replacement therapy (RRT). The current study investigated postural stability in a group of CKD patients not requiring RRT.
Methods
30 CKD patients (aged 57.0 ± 17.8 years, 47% female, mean eGFR 42.9 ± 27.2 ml/kg/1.73 m
2
) underwent a series of physical function assessments including the sit-to-stand-5 and -60, incremental shuttle walk test, gait speed, and short physical performance battery. Postural stability (defined as total COP ellipse (mm
2
) displacement) was measured using the Fysiometer board. Control reference data were provided by the manufacture. Cognitive function was assessed using the ‘Montreal Cognitive Assessment-Basic’ (MOCA-B)’.
Results
CKD patients had poorer postural stability during quiet standing than reference values across all age categories (≤ 39 years, 24.9 ± 11.3 vs. 10.4 ± 1.8 mm
2
; 40–59 years, 34.3 ± 19.0 vs. 17.7 ± 6.2 mm
2
; ≥ 60 years, 39.7 ± 21.2 vs. 16.8 ± 2.9 mm
2
, all comparisons
P
< 0.001). Reductions in postural stability were associated with both physical and cognitive functioning. In females only, postural stability worsened with declining renal function (
r
= − 0.790,
P
< 0.01).
Conclusions
To our knowledge, this is the first and largest experimental report concerning measurement of postural stability of CKD patients not requiring RRT. Our findings suggest that postural stability is associated with worse physical and cognitive functioning in this patient group.
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