Muscular Adaptations to Concurrent Resistance Training and High-Intensity Interval Training in Adults with Type 2 Diabetes: A Pilot Study.

This pilot study aimed to compare the effects of eight weeks of concurrent resistance training (RT) and high-intensity interval training (HIIT) vs. RT alone on muscle performance, mass and quality in adults with type 2 diabetes (T2DM). Twelve T2DM adults were randomly allocated to the RT + HIIT (n = 5) or RT (n = 7) group. Before and after training, maximal oxygen uptake (VO2max), muscle strength and power were evaluated by calorimetry, dynamometry and one-repetition maximum (1RM) test. Quadriceps muscle volume was determined by MRI, and muscle quality was estimated. After RT, VO2max (+12%), knee muscle power (+20%), quadriceps muscle volume (+5.9%) and quality (leg extension, +65.4%; leg step-up, +223%) and 1RM at leg extension (+66.4%), leg step-up (+267%), lat pulldown (+60.9%) and chest press (+61.2%) significantly increased. The RT + HIIT group improved on VO2max (+27%), muscle volume (+6%), muscle power (+9%) and 1RM at lat pulldown (+47%). No other differences were detected. Among groups, changes in muscle quality at leg step-up and leg extension and VO2max were significantly different. The combination of RT and HIIT effectively improves muscle function and size and increases cardiorespiratory fitness in adults with T2DM. However, HIIT combined with RT may interfere with the development of muscle quality.

Lower volume throughout the taper and higher intensity in the last interval session prior to a 1500 m time trial improves performance.

Eight highly trained middle-distance runners (1500 m personal best 4:01.4 ± 0:09.2 min) completed two 7-day tapers, separated by at least 3 weeks of regular training: (i) prescribed using prediction models from elite middle-distance runners, where continuous running volume was reduced by 30% and interval intensity was equal to 1500 m race pace (RP); and (ii) continuous running volume was reduced by 60% and intensity of the final interval session was completed at 110% of 1500 m race pace (HI). Performance was assessed using 1500 m time trials on an indoor 200 m track 1 day before, and 1 day after each taper. Performance time was improved after HI by 5.2 ± 3.7 s (mean ± 90% confidence limits, p = 0.03) and by 3.2 ± 3.8 s after RP (p = 0.15). The first and second 300 m segments of the 1500 m time trial were faster post-taper in RP (p = 0.012 and p = 0.017, respectively) and HI (both p = 0.012). Running faster than race pace late in a low-volume taper is recommended to improve 1500 m track performance. A positive pacing strategy is adopted after tapering, although care should be taken to avoid an over-fast start. Novelty: A large reduction in volume during tapering and an increase in final interval session intensity improves running performance. Athletes adopt a negative pacing strategy before tapering and a positive-pacing strategy after tapering.

Effects of an increase in intensity during tapering on 1500-m running performance.

We examined the effect of completing the final interval training session during a taper at either (i) race pace (RP) or (ii) faster than RP on 1500-m running performance and neuromuscular performance. Ten trained runners (age, 21.7 ± 3.0 years; height, 182.9 ± 7.0 cm; body mass, 73.4 ± 6.8 kg; and personal best 1500-m time, 4:17.5 ± 0:26.9 min) completed 2 conditions consisting of 7 days of regular training and a 7-day taper, separated by 3 weeks of training. In 1 condition, the taper was prescribed using prediction models based on the practices of elite British middle-distance runners, with the intensity of the final interval session being equal to 1500-m RP. The taper was repeated in the high-intensity (HI) condition, with the exception that the final interval session was completed at 115% of 1500-m RP. A 1500-m treadmill time trial and measures of maximal voluntary contraction (MVC) and rate of force development (RFD) were completed before and after regular training and tapering. Performance was most likely improved after RP (mean ± 90% confidence limits, 10.1 ± 1.6 s), and possibly beneficial after HI (4.2 ± 12.0 s). Both MVC force (p = 0.002) and RFD (p = 0.02) were improved after tapering, without differences between conditions. An RP taper based on the practices of elite middle-distance runners is recommended to improve performance in young, subelite runners. The effect of this strategy with an increase in interval intensity is highly variable and should be implemented with caution.

The Impact of a Novel Structured Health Intervention for Truckers (SHIFT) on Physical Activity and Cardiometabolic Risk Factors.

OBJECTIVE: The aim of this study was to examine the effects of implementing a lifestyle health behavior intervention on cardiovascular risk markers in a sample of lorry drivers. METHODS: Fifty-seven males participated in the pre-post evaluation of a multicomponent 12-week intervention. RESULTS: Favorable changes in several cardiovascular health indicators were observed, including fasting blood glucose (-0.6 mmol/L), LDL-Cholesterol (-0.7 mmol/L), total cholesterol (-0.7 mmol/L), waist-hip ratio (-0.10), and waist circumference (-2.5 cm) (P < 0.01). The proportion of participants with a more than 10% risk of a cardiovascular event in the next 10 years was reduced by 12% (P < 0.05). A 21%, 12%, and 7.5% reduction in drivers with pre-diabetes (P < 0.001), undiagnosed diabetes (P < 0.05), and the metabolic syndrome (P < 0.05), respectively, was observed. CONCLUSION: This study highlights the feasibility of implementing a multicomponent health intervention within the transport setting and provides preliminary evidence of its beneficial effects on some markers of health.

Effects of sprint interval training on ectopic lipids and tissue-specific insulin sensitivity in men with non-alcoholic fatty liver disease.

PURPOSE: This study examined the feasibility of sprint interval exercise training (SIT) for men with non-alcoholic fatty liver disease (NAFLD) and its effects on intrahepatic triglyceride (IHTG), insulin sensitivity (hepatic and peripheral), visceral (VAT) and subcutaneous adipose tissue (ScAT). METHODS: Nine men with NAFLD (age 41 ± 8 years; BMI 31.7 ± 3.1 kg m-2; IHTG 15.6 ± 8.3%) were assessed at: (1) baseline (2) after a control phase of no intervention (pre-training) and (3) after 6 weeks of SIT (4-6 maximal 30 s cycling intervals, three times per week). IHTG, VAT and ScAT were measured using magnetic resonance spectroscopy or imaging and insulin sensitivity was assessed via dual-step hyperinsulinaemic-euglycaemic clamp with [6,6-D2] glucose tracer. RESULTS: Participants adhered to SIT, completing ≥ 96.7% of prescribed intervals. SIT increased peak oxygen uptake [[Formula: see text] peak: + 13.6% (95% CI 8.8-18.2%)] and elicited a relative reduction in IHTG [- 12.4% (- 31.6 to 6.7%)] and VAT [- 16.9% (- 24.4 to - 9.4%); n = 8], with no change in body weight or ScAT. Peripheral insulin sensitivity increased throughout the study (n = 8; significant main effect of phase) but changes from pre- to post-training were highly variable (range - 18.5 to + 58.7%) and not significant (P = 0.09), despite a moderate effect size (g* = 0.63). Hepatic insulin sensitivity was not influenced by SIT. CONCLUSIONS: SIT is feasible for men with NAFLD in a controlled laboratory setting and is able to reduce IHTG and VAT in the absence of weight loss.

A Structured Health Intervention for Truckers (SHIFT): A Process Evaluation of a Pilot Health Intervention in a Transport Company.

OBJECTIVES: To undertake a process-evaluation of a structured health intervention for truckers (SHIFT) implemented in a sample of UK lorry drivers. METHODS: A combination of "debrief interviews," focus groups and one-to-one interviews, in addition to observations and reflections of the two lead researchers were used to collect data on the acceptability of SHIFT from a group of 16 lorry drivers and four transport managers. RESULTS: The SHIFT program was considered relevant and acceptable to lorry drivers. It provided them with health information tailored to their specific health needs, long-lasting tools and techniques, which helped to raise their awareness of key health issues and helped to stimulate lifestyle changes during their daily routine. CONCLUSION: This process-evaluation suggests that the SHIFT program should now be evaluated on a larger scale and tested through fully randomized controlled trials.

The influence of adiposity and acute exercise on circulating hepatokines in normal-weight and overweight/obese men.

Hepatokines are liver-secreted proteins with potential to influence glucose regulation and other metabolic parameters. This study investigated differences in adiposity status on 5 novel hepatokines and characterised their response to acute moderate-intensity exercise in groups of normal-weight and overweight/obese men. Twenty-two men were recruited into normal-weight and overweight/obese groups (body mass index: 18.5 to 24.9 and 25.0 to 34.9 kg·m-2). Each completed 2 experimental trials, exercise and control. During exercise trials, participants performed 60 min of moderate-intensity treadmill exercise (∼60% peak oxygen uptake) and then rested for 6 h. Participants rested throughout control trials. Circulating fibroblast growth factor-21 (FGF21), follistatin, leukocyte cell-derived chemotaxin 2 (LECT2), fetuin-A, and selenoprotein-P (SeP) were measured throughout. Fasted (resting) FGF21 and LECT2 were higher in overweight/obese individuals (129% and 55%; P ≤ 0.01) and correlated with indices of adiposity and insulin resistance; whereas circulating follistatin was lower in overweight/obese individuals throughout trial days (17%, P < 0.05). In both groups, circulating concentrations of FGF21 and follistatin were transiently elevated after exercise for up to 6 h (P ≤ 0.02). Circulating fetuin-A and SeP were no different between groups (P ≥ 0.19) and, along with LECT2, were unaffected by exercise (P ≥ 0.06). These findings show that increased adiposity is associated with a modified hepatokine profile, which may represent a novel mechanism linking excess adiposity to metabolic health. Furthermore, acute perturbations in circulating FGF21 and follistatin after exercise may contribute to the health benefits of an active lifestyle.

Satellite cell response to concurrent resistance exercise and high-intensity interval training in sedentary, overweight/obese, middle-aged individuals.

PURPOSE: Sarcopenia can begin from the 4-5th decade of life and is exacerbated by obesity and inactivity. A combination of resistance exercise (RE) and endurance exercise is recommended to combat rising obesity and inactivity levels. However, work continues to elucidate whether interference in adaptive outcomes occur when RE and endurance exercise are performed concurrently. This study examined whether a single bout of concurrent RE and high-intensity interval training (HIIT) alters the satellite cell response following exercise compared to RE alone. METHODS: Eight sedentary, overweight/obese, middle-aged individuals performed RE only (8 × 8 leg extensions at 70% 1RM), or RE + HIIT (10 × 1 min at 90% HRmax on a cycle ergometer). Muscle biopsies were collected from the vastus lateralis before and 96 h after the RE component to determine muscle fiber type-specific total (Pax7+ cells) and active (MyoD+ cells) satellite cell number using immunofluorescence microscopy. RESULTS: Type-I-specific Pax7+ (P = 0.001) cell number increased after both exercise trials. Type-I-specific MyoD+ (P = 0.001) cell number increased after RE only. However, an elevated baseline value in RE + HIIT compared to RE (P = 0.046) was observed, with no differences between exercise trials at 96 h (P = 0.21). Type-II-specific Pax7+ and MyoD+ cell number remained unchanged after both exercise trials (all P ≥ 0.13). CONCLUSION: Combining a HIIT session after a single bout of RE does not interfere with the increase in type-I-specific total, and possibly active, satellite cell number, compared to RE only. Concurrent RE + HIIT may offer a time-efficient way to maximise the physiological benefits from a single bout of exercise in sedentary, overweight/obese, middle-aged individuals.

Cross-sectional surveillance study to phenotype lorry drivers' sedentary behaviours, physical activity and cardio-metabolic health.

OBJECTIVES: Elevated risk factors for a number of chronic diseases have been identified in lorry drivers. Unhealthy lifestyle behaviours such as a lack of physical activity (PA) and high levels of sedentary behaviour (sitting) likely contribute to this elevated risk. This study behaviourally phenotyped UK lorry drivers' sedentary and non-sedentary behaviours during workdays and non-workdays and examined markers of drivers cardio-metabolic health. SETTING: A transport company from the East Midlands, UK. PARTICIPANTS: A sample of 159 male heavy goods vehicle drivers (91% white European; (median (range)) age: 50 (24, 67) years) completed the health assessments. 87 (age: 50.0 (25.0, 65.0); body mass index (BMI): 27.7 (19.6, 43.4) kg/m2) provided objective information on sedentary and non-sedentary time. OUTCOMES: Participants self-reported their sociodemographic information. Primary outcomes: sedentary behaviour and PA, assessed over 7 days using an activPAL3 inclinometer. Cardio-metabolic markers included: blood pressure (BP), heart rate, waist circumference (WC), hip circumference, body composition and fasted capillary blood glucose, triglycerides, high-density lipopreotein cholesterol, low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) levels. These cardio-metabolic markers were treated as secondary outcomes. RESULTS: Lorry drivers presented an unhealthy cardio-metabolic health profile (median (IQR) systolic BP: 129 (108.5, 164) mm Hg; diastolic BP: 81 (63, 104) mm Hg; BMI: 29 (20, 47) kg/m2; WC: 102 (77.5, 146.5) cm; LDL-C: 3 (1, 6) mmol/L; TC: 4.9 (3, 7.5) mmol/L). 84% were overweight or obese, 43% had type 2 diabetes or prediabetes and 34% had the metabolic syndrome. The subsample of lorry drivers with objective postural data (n=87) accumulated 13 hours/day and 8 hours/day of sedentary behaviour on workdays and non-workdays (p<0.001), respectively. On average, drivers accrued 12 min/day on workdays and 6 min/day on non-workdays of moderate-to-vigorous PA (MVPA). CONCLUSION: Lorry drivers demonstrate a high-risk cardio-metabolic profile and are highly sedentary and physically inactive. Interventions to reduce sitting and increase MVPA during breaks and leisure time to improve cardio-metabolic health are urgently needed. Educational programmes to raise awareness about diet and exercise are recommended.

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

ᅟ: 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. TRIAL REGISTRATION: This trial reports data from human participants and was retrospectively registered on 22/02/2017 with the ISRCTN registry, trial number ISRCTN90672085.

Reducing sedentary time in adults at risk of type 2 diabetes: process evaluation of the STAND (Sedentary Time ANd Diabetes) RCT.

BACKGROUND: Reducing sedentary behaviour may have important health implications. This study evaluated the potential enablers and barriers for outcomes of a randomised controlled trial (RCT) designed to evaluate a pragmatic education based intervention designed to reduce sedentary (sitting) behaviour in young adults at high risk of type 2 diabetes. METHODS: Data were collected from participants in the intervention group immediately after an educational workshop addressing sedentary time and diabetes risk (n = 71), through phone interviews 6 weeks (n = 45) after the workshop, and at the conclusion of the 12-month trial (n = 10). The two education session facilitators were also interviewed about the intervention. RESULTS: The RCT showed no difference in sedentary time at 12 months between intervention and control arms. The lack of behaviour change appeared not to be attributed to the workshops, which were well led and very favourably received according to feedback. However, factors contributing to this lack of behaviour change include lack of perceived health risk from baseline measures feedback; the preference to adopt physically active behaviours rather than to sit less; certain barriers to sitting less; motivational drift after the 3-month follow-up measurements where participants had no contact for a further 9 months; and, for some, unreliability of the self-monitoring tool. CONCLUSIONS: The workshop was well led and well received by the attendees but future interventions need to consider more contact with participants, discuss any specific benefits around simply standing to reduce sitting time, address the barriers to sitting less, and provide a more user-friendly and reliable self-monitoring tool. TRIAL REGISTRATION: Current controlled trials ISRCTN08434554 , MRC project 91409. Registered retrospectively on 22 February 2011.

Understanding the health of lorry drivers in context: A critical discourse analysis.

This article moves beyond previous attempts to understand health problems in the lives of professional lorry drivers by placing the study of drivers' health in a wider social and cultural context. A combination of methods including focus groups, interviews and observations were used to collect data from a group of 24 lorry drivers working at a large transport company in the United Kingdom. Employing a critical discourse analysis, we identified the dominant discourses and subject positions shaping the formation of drivers' health and lifestyle choices. This analysis was systematically combined with an exploration of the gendered ways in which an almost exclusively male workforce talked about health. Findings revealed that drivers were constituted within a neoliberal economic discourse, which is reflective of the broader social structure, and which partly restricted drivers' opportunities for healthy living. Concurrently, drivers adopted the subject position of 'average man' as a way of defending their personal and masculine status in regards to health and to justify jettisoning approaches to healthy living that were deemed too extreme or irrational in the face of the constraints of their working lives. Suggestions for driver health promotion include refocusing on the social and cultural - rather than individual - underpinnings of driver health issues and a move away from moralistic approaches to health promotion.

A Randomised Controlled Trial to Reduce Sedentary Time in Young Adults at Risk of Type 2 Diabetes Mellitus: Project STAND (Sedentary Time ANd Diabetes).

AIMS: Type 2 diabetes mellitus (T2DM), a serious and prevalent chronic disease, is traditionally associated with older age. However, due to the rising rates of obesity and sedentary lifestyles, it is increasingly being diagnosed in the younger population. Sedentary (sitting) behaviour has been shown to be associated with greater risk of cardio-metabolic health outcomes, including T2DM. Little is known about effective interventions to reduce sedentary behaviour in younger adults at risk of T2DM. We aimed to investigate, through a randomised controlled trial (RCT) design, whether a group-based structured education workshop focused on sitting reduction, with self-monitoring, reduced sitting time. METHODS: Adults aged 18-40 years who were either overweight (with an additional risk factor for T2DM) or obese were recruited for the Sedentary Time ANd Diabetes (STAND) RCT. The intervention programme comprised of a 3-hour group-based structured education workshop, use of a self-monitoring tool, and follow-up motivational phone call. Data were collected at three time points: baseline, 3 and 12 months after baseline. The primary outcome measure was accelerometer-assessed sedentary behaviour after 12 months. Secondary outcomes included other objective (activPAL) and self-reported measures of sedentary behaviour and physical activity, and biochemical, anthropometric, and psycho-social variables. RESULTS: 187 individuals (69% female; mean age 33 years; mean BMI 35 kg/m2) were randomised to intervention and control groups. 12 month data, when analysed using intention-to-treat analysis (ITT) and per-protocol analyses, showed no significant difference in the primary outcome variable, nor in the majority of the secondary outcome measures. CONCLUSIONS: A structured education intervention designed to reduce sitting in young adults at risk of T2DM was not successful in changing behaviour at 12 months. Lack of change may be due to the brief nature of such an intervention and lack of focus on environmental change. Moreover, some participants reported a focus on physical activity rather than reductions in sitting per se. The habitual nature of sedentary behaviour means that behaviour change is challenging. TRIAL REGISTRATION: Controlled-Trials.com ISRCTN08434554.

Acute molecular responses to concurrent resistance and high-intensity interval exercise in untrained skeletal muscle.

Concurrent training involving resistance and endurance exercise may augment the benefits of single-mode training for the purpose of improving health. However, muscle adaptations, associated with resistance exercise, may be blunted by a subsequent bout of endurance exercise, via molecular interference. High-intensity interval training (HIIT), generating similar adaptations to endurance exercise, may offer an alternative exercise mode to traditional endurance exercise. This study examined the influence of an acute HIIT session on the molecular responses following resistance exercise in untrained skeletal muscle. Ten male participants performed resistance exercise (4 × 8 leg extensions, 70% 1RM, (RE)) or RE followed by HIIT (10 × 1 min at 90% HRmax, (RE+HIIT)). Muscle biopsies were collected from the vastus lateralis before, 2 and 6 h post-RE to determine intramuscular protein phosphorylation and mRNA responses. Phosphorylation of Akt (Ser(473)) decreased at 6 h in both trials (P < 0.05). Phosphorylation of mTOR (Ser(2448)) was higher in RE+HIIT (P < 0.05). All PGC-1α mRNA variants increased at 2 h in RE+HIIT with PGC-1α and PGC-1α-ex1b remaining elevated at 6 h, whereas RE-induced increases at 2 and 6 h for PGC-1α-ex1b only (P < 0.05). Myostatin expression decreased at 2 and 6 h in both trials (P < 0.05). MuRF-1 was elevated in RE+HIIT versus RE at 2 and 6 h (P < 0.05). Atrogin-1 was lower at 2 h, with FOXO3A downregulated at 6 h (P < 0.05). These data do not support the existence of an acute interference effect on protein signaling and mRNA expression, and suggest that HIIT may be an alternative to endurance exercise when performed after resistance exercise in the same training session to optimize adaptations.

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 (10:30-12:00h). 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)·7h, 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)·3h, 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 24h time-frame however there is no conscious recognition of the perturbation to energy balance.

Tapering strategies in elite British endurance runners.

The aim of the study was to explore pre-competition training practices of elite endurance runners. Training details from elite British middle distance (MD; 800 m and 1500 m), long distance (LD; 3000 m steeplechase to 10,000 m) and marathon (MAR) runners were collected by survey for 7 days in a regular training (RT) phase and throughout a pre-competition taper. Taper duration was [median (interquartile range)] 6 (3) days in MD, 6 (1) days in LD and 14 (8) days in MAR runners. Continuous running volume was reduced to 70 (16)%, 71 (24)% and 53 (12)% of regular levels in MD, LD and MAR runners, respectively (P < 0.05). Interval running volume was reduced compared to regular training (MD; 53 (45)%, LD; 67 (23)%, MAR; 64 (34)%, P < 0.05). During tapering, the peak interval training intensity was above race speed in LD and MAR runners (112 (27)% and 114 (3)%, respectively, P < 0.05), but not different in MD (100 (2)%). Higher weekly continuous running volume and frequency in RT were associated with greater corresponding reductions during the taper (R = -0.70 and R = -0.63, respectively, both P < 0.05). Running intensity during RT was positively associated with taper running intensity (continuous intensity; R = 0.97 and interval intensity; R = 0.81, both P < 0.05). Algorithms were generated to predict and potentially prescribe taper content based on the RT of elite runners. In conclusion, training undertaken prior to the taper in elite endurance runners is predictive of the tapering strategy implemented before competition.

Associations of Sedentary Time with Fat Distribution in a High-Risk Population.

PURPOSE: The effect of sedentary behavior on regional fat deposition, independent of physical activity, remains equivocal. We examined the cross-sectional associations between objectively measured sedentary time and markers of regional fat distribution (heart, liver, visceral, subcutaneous, and total body fat) in a population at a high risk of type 2 diabetes mellitus (T2DM). METHODS: Participants were recruited from primary care to two diabetes prevention programs. Sedentary time (<25 counts per 15 s) was measured using ActiGraph GT3X accelerometers. Heart, liver, visceral, subcutaneous, and total body fat were quantified using magnetic resonance images. Fat volumes were calculated by multiplying the cross-sectional areas of the fat-containing pixels by the slice thickness. The liver fat percentage was measured using a representative region of interest created in the right lobe of the liver, avoiding the main portal veins. Linear regression models examined the association of sedentary time with markers of regional fat deposition. RESULTS: Sixty-six participants (age, 47.9 ± 16.2 yr; male, 50.0%) were included. After adjustment for several covariates, including glycemia, whole-body fat, and moderate-to-vigorous physical activity, each 30 min of sedentary time was associated with 15.7 cm higher heart fat (P = 0.008), 1.2% higher liver fat (P = 0.026), and 183.7 cm higher visceral fat (P = 0.039). CONCLUSIONS: This study provides new evidence suggesting that objectively measured sedentary behavior may have an independent association with heart, liver, and visceral fat in individuals at a high risk of T2DM.

The detection and measurement of interleukin-6 in venous and capillary blood samples, and in sweat collected at rest and during exercise.

PURPOSE: This study aimed to quantify the relationship between venous and capillary blood sampling methods for the measurement of plasma interleukin-6 (IL-6). A parallel study was conducted to determine the possibility of measuring IL-6 in sweat using an enzyme-linked immunosorbent assay (ELISA) and investigate the relationship between plasma- and sweat-derived measures of IL-6. METHODS: Twelve male participants were recruited for the measurement of IL-6 at rest and during exercise (study 1). An additional group of five female participants was recruited for the measurement of IL-6 in venous blood versus sweat at rest and following exercise (study 2). In study 1, venous and capillary blood samples were collected at rest and in response to exercise. In study 2, venous and sweat samples were collected following exercise. RESULTS: Mean plasma IL-6 concentration was not different between venous and capillary blood sampling methods either at rest (4.27 ± 5.40 vs. 4.14 ± 4.45 pg ml(-1)), during (5.40 ± 5.17 vs. 5.58 ± 6.34 pg ml(-1)), or in response to exercise (6.95 ± 6.37 vs. 6.99 ± 6.74 pg ml(-1)). There was no IL-6 detectable in sweat either at rest or following exercise. CONCLUSION: There are no differences in the measurement of plasma IL-6 using either venous or capillary blood sampling methods. Capillary measurement represents a minimally invasive way of measuring IL-6 and detecting changes in IL-6, which are linked to fatigue and overtraining.

The impact of high-intensity intermittent exercise on resting metabolic rate in healthy males.

INTRODUCTION: High-intensity intermittent exercise training (HIT) may favourably alter body composition despite low training volumes and predicted energy expenditure (EE). PURPOSE: To characterise the acute impact of two common HIT protocols on EE and post-exercise oxygen consumption (11 h EPOC). METHODS: Oxygen consumption (l min(-1)), respiratory exchange ratio (RER) and EE were measured in nine healthy, lean males over 12 h under three conditions: control (CON), HIT1 (10 × 1 min high-intensity cycling bouts followed by 1 min rest) and HIT2 (10 × 4 min high-intensity cycling bouts followed by 2 min rest). RESULTS: Total exercise period EE during HIT1 (1,151 ± 205 kJ) (mean ± SD) was significantly lower than HIT2 (2,788 ± 322 kJ; p < 0.001). EE within the 60 min after exercise was significantly albeit marginally higher after HIT1 (388 ± 44 kJ; p = 0.02) and HIT2 (389 ± 39 kJ; p = 0.01) compared with CON (329 ± 39 kJ), with no difference between exercise conditions (p = 0.778). RER during this period was significantly lower in HIT1 (0.78 ± 0.06; p = 0.011) and HIT2 (0.76 ± 0.04; p = 0.004) compared with CON (0.87 ± 0.06). During the 'slow phase' of EPOC (1.25-9.75 h), there were no significant differences in EE (p = 0.07) or RER (p = 0.173) between trials. CONCLUSIONS: Single HIT sessions notably increases EE during exertion; however, the influence on metabolic rate post-exercise is transient and relatively minor.

Exercise and ghrelin. A narrative overview of research.

Since its discovery in 1999, ghrelin has been implicated in a multiplicity of physiological activities. Most notably, ghrelin has an important influence on energy metabolism and after the identification of its potent appetite stimulating effects ghrelin has been termed the 'hunger hormone'. Exercise is a stimulus which has a significant impact on energy homeostasis and consequently a substantial body of research has investigated the interaction between exercise and ghrelin. This narrative review provides an overview of research relating to the acute and chronic effects of exercise on circulating ghrelin (acylated, unacylated and total). To enhance study comparability, the scope of this review is limited to research undertaken in adult humans and consequently studies involving children and animals are not discussed. Although there is significant ambiguity within much of the early research, our review suggests that acute exercise transiently interferes with the production of acylated ghrelin. Furthermore, the consensus of evidence indicates that exercise training does not influence circulating ghrelin independent of weight loss. Additional research is needed to verify and extend the available literature, particularly by uncovering the mechanisms governing acute exercise-related changes and characterising responses in other populations such as females, older adults, and the obese.