An evaluation of low volume high-intensity intermittent training (HIIT) for health risk reduction in overweight and obese men

Both sprint interval training (SIT) and high-intensity intermittent training (HIIT) have been described as time-efficient strategies for inducing favourable metabolic and cardiorespiratory adaptations in healthy and diseased participants. BACKGROUND: To date, little attention has been given to profiling the potential health benefits of HIIT or modified HIIT training within overweight and obese cohorts with particular focus on inflammation. Within this pilot trial, we tested the hypothesis that 6 sessions of HIIT performed over 2 weeks with 1-2 days’rest would improve aerobic capacity, glucose metabolism and inflammatory profile in an overweight and obese male cohort. Additionally, we profiled the potential health benefits of 4 HIIT sessions performed over the same period. METHODS: 18 overweight or obese males (BMI = 31.2 ± 3.6; V̇O2 = 30.3 ± 4.4 ml.kg.min-1) were studied before and 72 h after HIIT. Training sessions consisted of 10 x 1 min intervals at 90% HRpeak separated by 1 min recovery periods. Exercise was performed either 6 (group 1, n = 8) or 4 (group 2, n = 10)times over a 2 week period. RESULTS: After training no changes were detected from baseline for body composition, aerobic capacity, glucose metabolism or inflammatory profile(p > 0.05) in either group. CONCLUSION: Both 6 and 4 sessions of HIIT performed over a 2-week period are ineffective in improving selected health markers within an overweight and obese cohort

Appetite regulatory hormone responses on the day following a prolonged bout of moderate-intensity exercise

Exercise increases energy expenditure however acutely this does not cause compensatory changes in appetite or food intake. This unresponsiveness contrasts the rapid counter-regulatory changes seen after food restriction. The present investigation examined whether corrective changes in appetite-regulatory parameters occur after a time delay, namely, on the day after a single bout of exercise. Nine healthy males completed two, two-day trials (exercise & control) in a random order. On the exercise trial participants completed 90 min of moderate-intensity treadmill running on day one (10:30–12:00 h). On day two appetite-regulatory hormones and subjective appetite perceptions were assessed frequently in response to two test meals provided at 08:00 and 12:00 h. Identical procedures occurred in the control trial except no exercise was performed on day one. Circulating levels of leptin were reduced on the day after exercise (AUC 5841 ± 3335 vs. 7266 ± 3949 ng− 1·mL− 1 · 7 h, P = 0.012). Conversely, no compensatory changes were seen for circulating acylated ghrelin, total PYY, insulin or appetite perceptions. Unexpectedly, levels of acylated ghrelin were reduced on the exercise trial following the second test meal on day two (AUC 279 ± 136 vs. 326 ± 136 pg− 1·mL− 1 · 3 h, P = 0.021). These findings indicate that short-term energy deficits induced by exercise initially prompt a compensatory response by chronic but not acute hormonal regulators of appetite and energy balance. Within this 24 h time-frame however there is no conscious recognition of the perturbation to energy balance

Exercise Training in Chronic Kidney Disease: Impact on Cardiovascular Risk Factors

Cardiovascular disease is the leading cause of morbidity and mortality in people with chronic kidney disease (CKD). Cardiovascular disease in CKD is usually attributed to traditional cardiovascular risk factors and / or novel risk factors specific to kidney disease. Several risk factors may potentially be modified through exercise training to reduce cardiovascular complications. The aims of this thesis were to characterise the ExTra CKD population by providing baseline data in terms of demographics, aerobic and functional capacity, cardiac output measurements, markers of inflammation and iron metabolism, to evaluate the reliability of brachial artery flow mediated dilation (BA-FMD) to assess endothelial function, to establish readily available methods in assessing aerobic capacity (VO2Peak) (a prognostic biomarker of survival in this patient population) and to assess the effects of 12 weeks of aerobic exercise (AE) or combined aerobic and resistance exercise (CE) on four interconnected risk factors namely aerobic and functional capacity, endothelial function, chronic inflammation and iron metabolism. VO2Peak values in the present cohort were similar to those reported in cardiovascular disease cohorts and lower than values reported in healthy age matched counterparts (Chapter 3). Additionally, hepcidin-25 (a key regulator of iron homeostasis) and haemoglobin levels in the present cohort were significantly different to age matched controls (Chapter 7). BA-FMD showed good inter-operator reliability with regards to scan interpretation, however no changes were shown following exercise (Chapter 4). Chapter 5 demonstrates that VO2Peak can be estimated using an incremental shuttle walking test and the Duke Activity Status Index with similar accuracy as expensive laboratory based cardiopulmonary exercise tests. Estimated VO2Peak calculated using the equations in Chapter 5 improved following both CE and AE (Chapter 6). Despite the known anti-inflammatory properties of exercise, no changes in inflammatory profile were shown following exercise. Interestingly, hepcidin-25 was reduced following exercise (Chapter 7).</p

The ‘minimum clinically important difference’ in frequently reported objective physical function tests following a 12-week renal rehabilitation exercise intervention in non-dialysis chronic kidney disease

Objective Chronic kidney disease (CKD) patients are characterized by impaired physical function. The goal of exercise-based interventions is an improvement in functional performance. However, improvements are often determined by ‘statistically significant’ changes. We investigated the ‘minimum clinically important difference’ (MCID), ‘the smallest change that is important to the patient’, for commonly reported physical function tests. Design Non-dialysis CKD patients completed 12-weeks of a combined aerobic (plus resistance training). The incremental shuttle walking test (ISWT), sit-to-stand-5 (STS-5) and 60 (STS-60), estimated 1 repetition maximum (e1RM) for the knee extensors, and VO2peak were assessed. After the intervention, patients rated their perceived change in health. Both anchor- and distribution-based MCID approaches were calculated. Results The MCID was calculated as follows: ISWT, +45m; STS-5, -4.2 seconds; VO2peak, +1.5 ml/kg/min. Due to comparable increases in ‘anchor’ groups, no MCID was estimated for the STS-60 or e1RM. Conclusion We have established the MCID in CKD for common tests of physical function. These values represent the minimum change required for patients to perceive noticeable and beneficial change to their health. These scores will help interpret changes following exercise interventions where these tests are employed. These MCIDs can be used to power future studies to detect clinically important changes

Test–retest reliability, validation, and “minimal detectable change” scores for frequently reported tests of objective physical function in patients with non-dialysis chronic kidney disease

Physical function is an important outcome in chronic kidney disease (CKD). We aimed to establish the reliability, validity, and the “minimal detectable change” (MDC) of several common tests used in renal rehabilitation and research. In a repeated measures design, 41 patients with CKD not requiring dialysis (stage 3b to 5) were assessed at an interval of 6 weeks. The tests were the incremental shuttle walk test (ISWT), “sit-to-stand” (STS) test, estimated 1 repetition maximum for quadriceps strength (e1RM), and VO2peak by cardiopulmonary exercise testing (CPET). Reliability was assessed using intraclass correlation coefficient and Bland–Altman analysis, and absolute reliability by standard error of measurement and MDC. The ISWT, STS-60, e1RM, and CPET had “good” to “excellent” reliability (0.973, 0.927, 0.927, and 0.866), respectively. STS-5 reliability was poor (0.676). The MDC is ISWT, 20 m; STS-5, 7.5 s; STS-60, 4 reps; e1RM, 6.4 kg; VO2peak, 2.8 ml/kg/min. There was strong correlation between the ISWT and VO2peak (r = 0.73 and 0.74). While there was poor correlation between the STS-5 and e1RM (r = 0.14 and 0.47), better correlation was seen between STS-5 and ISWT (r = 0.55 and 0.74). In conclusion, the ISWT, STS-60, e1RM, and CPET are reliable tests of function in CKD. The ISWT is a valid means of exercise capacity. The MDC can help researchers and rehabilitation professionals interpret changes following an intervention

Inflammation and physical dysfunction: responses to moderate intensity exercise in chronic kidney disease

BackgroundPeople with chronic kidney disease (CKD) experience skeletal muscle wasting, reduced levels of physical function and performance, and chronic systemic inflammation. While it is known that a relationship exists between inflammation and muscle wasting, the association between inflammation and physical function or performance in CKD has not been well studied. Exercise has anti-inflammatory effects, but little is known regarding the effect of moderate intensity exercise. This study aimed to (i) compare systemic and intramuscular inflammation between CKD stage G3b–5 and non-CKD controls; (ii) establish whether a relationship exists between physical performance, exercise capacity and inflammation in CKD; (iii) determine changes in systemic and intramuscular inflammation following 12 weeks of exercise; and (iv) investigate whether improving inflammatory status via training contributes to improvements in physical performance and muscle mass.MethodsThis is a secondary analysis of previously collected data. CKD patients stages G3b–5 (n = 84, n = 43 males) and non-CKD controls (n = 26, n = 17 males) underwent tests of physical performance, exercise capacity, muscle strength and muscle size. In addition, a subgroup of CKD participants underwent 12 weeks of exercise training, randomized to aerobic (AE, n = 21) or combined (CE, n = 20) training. Plasma and intramuscular inflammation and myostatin were measured at rest and following exercise.ResultsTumour necrosis factor-α was negatively associated with lower .VO2Peak (P = 0.01), Rectus femoris-cross sectional area (P = 0.002) and incremental shuttle walk test performance (P ConclusionsSystemic inflammation may contribute to reduced physical function in CKD. Twelve weeks of exercise training was unable to reduce the level of chronic systemic inflammation in these patients, but did reduce plasma myostatin concentrations. Further research is required to further investigate this.</div

12-weeks combined resistance and aerobic training confers greater benefits than aerobic alone in non-dialysis CKD.

There is a growing consensus that chronic kidney disease (CKD) patients should engage in regular exercise, but there is a lack of formal guidelines. In this report, we determined whether combined aerobic and resistance exercise would elicit superior physiological gains, in particular muscular strength, compared to aerobic training alone in non-dialysis CKD. Non-dialysis CKD patients stage 3b-5 were randomly allocated to aerobic exercise (AE, n=21; 9 males; median age 63years [IQR, 58-71]; median eGFR 24[IQR, 20-30] mL/min/1.73m2) or combined exercise (CE, n=20, 9 males, median age 63years [IQR, 51-69], median eGFR 27[IQR, 22-32] mL/min/1.73m2), preceded by a 6-week run in control period. Patients then underwent 12-weeks of supervised AE (treadmill, rowing or cycling exercise) or CE training (as AE plus leg extension and leg press exercise) performed 3x/week. Outcome assessments of knee extensor muscle strength, quadriceps muscle volume, exercise capacity and central haemodynamics were performed at baseline, following the 6-week control period and at the end of the intervention. AE and CE resulted in significant increases in knee extensor strength of 1619% (P=0.001) and 4837% (P<0.001) respectively, which were greater after CE (P=0.02). AE and CE resulted in 57% (P=0.04) and 97% (P<0.001) increases in quadriceps volume respectively (P<0.001) which was greater after CE (P=0.01). Both AE and CE increased distance walked in ISWT (2844m; P=0.01 and 3245m P=0.01) respectively. In non-dialysis CKD, the addition of resistance exercise to aerobic exercise confers greater increases in muscle mass and strength than aerobic exercise alone

The association of physical function and physical activity with all-cause mortality and adverse clinical outcomes in non-dialysis chronic kidney disease: a systematic review.

Objective: People with non-dialysis dependent chronic kidney disease (CKD) and renal transplant recipients (RTR) have compromised physical function and reduced physical activity (PA) levels. Whilst established in healthy older adults and other chronic diseases, this association remains underexplored in CKD. We aimed to review the existing research investigating poor physical function and PA with clinical outcome in non-dialysis CKD. Data sources: Electronic databases (PubMed, MEDLINE, EMBASE, Web of Science, Cochrane Central Register of Controlled Trials) were searched until December 2017 for cohort studies reporting objective/subjective measures of PA/physical function and the associations with adverse clinical outcomes/all-cause mortality for patients with non-dialysis chronic kidney disease stages 1 to 5 and RTR. The protocol was registered on the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42016039060). Review methods: Study quality was assessed using the Newcastle-Ottawa Scale and the Agency for Healthcare and Research Quality (AHRQ) standards. Results: 29 studies were included; 12 reporting on physical function and 17 on PA. Only 8 studies were conducted with RTR. The majority were classified as “Good” according to the AHRQ standards. Although not appropriate for meta-analysis due to variance in the outcome measures reported, a coherent pattern was seen with higher mortality rates and/or prevalence of adverse clinical events associated with lower PA and physical function levels, irrespective of the measurement tool used. Sources of bias included incomplete description of participant flow through the study and over-reliance on self-report measures. Conclusions: In non-dialysis CKD, survival rates correlate with greater PA and physical function levels. Further trials are required to investigate causality and the effectiveness of physical function/physical activity interventions in improving outcomes. Future work should identify standard assessment protocols for PA and physical function

Supplementary_material_1_-_Example_PubMed_search_strat – Supplemental material for The association of physical function and physical activity with all-cause mortality and adverse clinical outcomes in nondialysis chronic kidney disease: a systematic review

<p>Supplemental material, Supplementary_material_1_-_Example_PubMed_search_strat for The association of physical function and physical activity with all-cause mortality and adverse clinical outcomes in nondialysis chronic kidney disease: a systematic review by Heather J. MacKinnon, Thomas J. Wilkinson, Amy L. Clarke, Douglas W. Gould, Thomas F. O’Sullivan, Soteris Xenophontos, Emma L. Watson, Sally J. Singh and Alice C. Smith in Therapeutic Advances in Chronic Disease</p

Association between vitamin D deficiency and exercise capacity in patients with CKD, a cross-sectional analysis.

BackgroundEvidence is growing for a role of vitamin D in regulating skeletal muscle mass, strength and functional capacity. Given the role the kidneys play in activating total vitamin D, and the high prevalence of vitamin D deficiency in Chronic Kidney Disease (CKD), it is possible that deficiency contributes to the low levels of physical function and muscle mass in these patients.MethodsThis is a secondary cross-sectional analysis of previously published interventional study, within vitro follow up work. 34 CKD patients at stages G3b-5 (eGFR 25.5 ± 8.3 ml/min/1.73m2; age 61 ± 12 years) were recruited, with a sub-group (n = 20) also donating a muscle biopsy. Vitamin D and associated metabolites were analysed in plasma by liquid chromatography tandem-mass spectroscopy and correlated to a range of physiological tests of muscle size, function, exercise capacity and body composition. The effects of 1α,25(OH)2D3 supplementation on myogenesis and myotube size was investigated in primary skeletal muscle cells from vitamin D deficient donors.ResultsIn vivo, there was no association between total or active vitamin D and muscle size or strength, but a significant correlation with V̇O2Peak was seen with total vitamin D (25OHD). In vitro, 1α,25(OH)2D3 supplementation reduced IL-6 mRNA expression, but had no effect upon proliferation, differentiation or myotube diameter.ConclusionsVitamin D deficiency is not a prominent factor driving the loss of muscle mass in CKD, but may play a role in reduced exercise capacity.</div